Applied Research最新文献

This tutorial-style article describes recent improvements in the quantitative application of energy-dispersive X-ray spectroscopy and mapping in electron microscopes to semiconductors, with a focus on spatial resolution, sensitivity and accuracy obtainable in characterising the chemical composition of thin layers, quantum wells and quantum dots. Various approaches applicable in scanning electron microscopy of bulk and (scanning) transmission electron microscopy of thin film samples are outlined. Applications to semiconductor quantum well systems, mainly based on indium gallium arsenide and silicon germanium studied in the author's laboratory, are provided as examples.

Lithium-sulfur battery (LSB) chemistry is regarded as one of the most promising contenders for powering next-generation electronics, including electric vehicles. This is due to its high theoretical capacity, the use of inexpensive and environmentally friendly materials, and its alignment with climate-smart manufacturing principles. Sulfur, the electroactive element in LSBs, undergoes lithiation to form a series of polysulfides, each contributing to the battery's energy density. However, this chemistry encounters several challenges, particularly concerning the stability of sulfur. Recent studies have shown that the presence of a full gamma phase of sulfur in an LSB cathode significantly enhances the capacity and overall cell performance. However, despite the advantages of cathodes with gamma sulfur, the characteristics of LSBs with mixed crystal phases of sulfur (alpha, beta, and gamma) have not been extensively studied. In this context, we developed a simple and cost-effective synthesis method to produce both single-phase (alpha) and mixed-phase sulfur (primarily a mixture of alpha and gamma, with a trace of beta) and conducted their detailed physical and electrochemical characterization for use as electroactive cathode materials in LSBs. The cells fabricated using sulfur-carbon black as the cathode delivered a specific capacity of approximately 640 mAh/g at a current density of 275 mA/g, demonstrating excellent cyclic stability over 50 cycles with a capacity retention of around 97%. This performance is superior to that of the sulfur-baked carbon black composite cathode, which achieved 440 mAh/g at the same current density.

The lungs are exposed to a hostile environment from both sites: the airways and the vasculature. However, an efficient gas exchange of oxygen (O₂) and CO₂ is only possible through a very thin alveolo-capillary membrane. Therefore, maintaining cell barrier integrity is essential for respiratory health and function. On the vascular site, endothelial cells form a natural barrier, while in the airways epithelial cells are most important for protection of the lung tissues. Moreover, fibroblasts, by transforming to myofibroblasts, are essential for wound closure after mechanical and chemical microinjuries in the respiratory tract. Along this line, loss of cell resistance in vascular endothelial and lung epithelial cells enhances invasion of pathogens (e.g., SARS-CoV-2) and results in pulmonary edema formation, while increasing barrier function of pulmonary (myo)fibroblasts blocks gas exchange in patients with pulmonary fibrosis. Therefore, electrical cell-substrate impedance sensing-based quantification of changes in cell barrier function in lung endothelial and epithelial cells as well as fibroblasts after application of harmful triggers (e.g., hypoxia, receptor agonists, and toxicants) is a convenient and state-of-the-art technique. After isolation of primary cells from mouse models and human tissues, changes in cell resistance can be detected in real time. By using lung cells from gene-deficient mouse models, microRNAs or the small-interfering RNA technology essential proteins for cell adhesion, for example, ion channels of the transient receptor potential family are identified in comparison to wild-type control cells. In the future, these proteins may be useful as drug targets for novel therapeutic options in patients with lung edema or pulmonary fibrosis.

A novel approach exploiting surfaces and interfaces between liquid oils and porous soil media was used to investigate the role of xanthan gum (XG) in minimizing the spread of petroleum oil spills on land. 1.6 wt% XG added to soil-based mixture matrixes (topsoil, sand, clay, and moisture) resulted in a 50% reduction in oil spreading area at 0 and 5 wt% moisture content, at 1.3 cm depth of soil matrix. Also recorded was a 45% increase in time taken for the low- and medium-viscosity oils to penetrate this soil depth. XG alters the surface energy and roughness of the soil matrixes, which additionally contributes to a reduction in oil spreading capabilities. Interfacial phenomena between individual oil droplets and soil matrixes demonstrated variable findings of droplet spreading and penetration with XG, depending upon the heterogeneity of the soil matrix itself. XG assisted a reduced lateral spread in heterogeneous soil matrixes and a reduced vertical penetration in clay-based matrixes. These interfacial results highlighted the often-observed differing transport phenomena at the interface compared with the bulk. This initial study demonstrates a novel approach to incorporate surface energy phenomena into the suite of soil remediation efforts by introducing natural biopolymers in high-risk land oil-spill areas to slow oil contaminant spread. Future studies will further characterize the benefits of XG in containing oil flow.

The main purpose of many current studies regarding energy efficiency is the improvement of the thermal resistance of buildings. To fulfill this goal, the development of advanced insulating materials, to be incorporated in the building envelopes, is imperative. Aerogels are ultralight porous materials typically produced via the sol-gel process followed by supercritical drying of the wet gel. They exhibit very high porosities and a mesoporous-macroporous structure which endows aerogels with extremely low thermal conductivity. This makes them ideal candidates for ambient thermal insulation applications. However, the cost for aerogel insulation is considerably higher than the one of standard insulation products. In the present work, highly porous aerogel-like materials based on silica and commercial novolac resin were developed and added to common mortars. The prepared materials were dried under ambient pressure to minimize the manufacturing cost. The bulk density of silica quasi-aerogels was 0.03 g/cm³–0.09 g/cm³ and that of the novolac resin samples 0.09 g/cm³–0.21 g/cm³. The aerogels were incorporated in mortars and cured for 28 days before measurement of thermal conductivity. The values of the thermal conductivity coefficient of the measured samples were 0.047 W/m K–0.058 W/m K for the silica reinforced mortars and 0.036 W/m K–0.044 W/m K for the novolac reinforced ones.

Climate change is one of the significant challenges of the 21st century. To achieve climate goals a change in plastic waste management needs to be implemented. This research examines the potential of thermo-mechanical recycling of plastic waste, focusing on agricultural binding twines made from polypropylene. Old binding twines from agriculture were collected and recycled with a twin screw extruder. The ageing behaviour of the recyclate in terms of multiple recycling is examined in detail with tensile tests and melt volume rate measurements. The findings indicate a general degradation in mechanical properties and a decrease in viscosity due to molecular chain scission. Despite these degradations, the material remains processable, indicating the potential for continued recycling loops.

Plasmonic sensors based on metal-insulator-metal (MIM) waveguides are renowned for their miniaturization and high sensitivity in various sensing applications. A broad spectrum of researchers is numerically investigating the characteristics of MIM waveguide-based plasmonic sensors with diverse cavity shapes. However, practical demonstrations of these sensors have not yet been realized, primarily due to the overlooked aspect of the light coupling mechanism into these waveguides. In this context, two distinct methods for coupling light into and out of plasmonic chips based on MIM waveguides are presented.

Silk fiber, often acclaimed as the pinnacle of textile materials, finds contemporary applications in the textile industry, health, and cosmetics. Gallic acid (GA) is a well-established natural antioxidant. In the present study, a novel hybrid material SFd@GA was conceptualized and produced via surface grafting of GA onto degummed silk-fibers (SFd). Successful covalent-grafting of gallic acid onto the silk fabric surface was confirmed through Fourier-transform infrared, Raman, thermogravimetric analysis (TG-DTA), and scanning electron microscopy (SEM). electron paramagnetic resonance spectroscopy demonstrates that gallic moieties grafted on SFd@GA retain their radical/redox activity. The antioxidant capacity of the hybrid material SFd@GA was validated by quantitative analysis of antioxidant hydrogen-atom-transfer (HAT) to DPPH radicals. Our data reveal a 550% increase in antioxidant-HAT activity of SFd@GA versus natural intact silk fiber, and a 1400% increase in antioxidant-HAT activity compared to the degummed silk fiber. The paramount discovery of the present work lies in the capacity for repeated utilization of the hybrid material SFd@GA, without any discernible compromise in its antioxidant-HAT activity. Specifically, we show that SFd@GA can be employed for at least 15 consecutive cycles, retaining >98% of its HAT efficiency, for up to many days of storage under ambient conditions. We discuss this expositional performance via the controllable Hat-activity process that we propose.

In this work, we introduce a novel image zooming methodology that transitions from a nonadaptive Sin-based approach to an adaptive Sinc-based zooming technique. The two techniques base their theoretical foundation on the Whittaker–Shannon interpolation formula and the Nyquist theorem. The evolution into adaptive Sinc-based zoom is accomplished through the use of two novel concepts: (1) the pixel-local scaled k-space and (2) the k-space filtering sigmoidal function. The pixel-local scaled k-space is the standardized and scaled k-space magnitude of the image to zoom. The k-space filtering sigmoidal function scales the pixel-local scaled k-space values into the numerical interval [0, 1]. Using these two novel concepts, the Whittaker–Shannon interpolation formula is elaborated and used to zoom images. Zooming is determined by the shape of the Sinc functions in the Whittaker–Shannon interpolation formula, which, in turn, depends on the combined effect of the pixel-local scaled k-space, the sampling rate, and the k-space filtering sigmoidal function. The primary outcome of this research demonstrates that the Whittaker–Shannon interpolation formula can achieve successful zooms for values of the sampling rate significantly greater than the bandwidth. Conversely, when the sampling rate is much greater than the bandwidth, the nonadaptive technique fails to perform the zoom correctly. The conclusion is that the k-space filtering sigmoidal function is identified as the crucial parameter in the adaptive Sinc-based zoom technique. The implications of this research extend to Sinc-based image zooming applications.

The design and development of photoinitiating systems applicable to visible light delivered from light-emitting diodes (LEDs) have attracted increasing attention owing to the wide application of photopolymerization. In this study, four aryl glycine derivatives are designed and synthesized, and their applicability as visible light-sensitive photoinitiators is thoroughly investigated. Specifically, the photoinitiation mechanism of these aryl glycine derivatives, when combined with iodonium salt, is investigated using steady-state photolysis, fluorescence, and electron paramagnetic resonance spin trapping techniques. It is revealed that radicals can be generated from aryl glycine derivatives/iodonium salt combinations upon exposure to blue LEDs (410 and 445 nm) to induce free radical photopolymerization (FRP) of (meth)acrylates. Additionally, besides FRP, a photobase generator based on one of the investigated aryl glycine derivatives is synthesized and demonstrates the capability to initiate epoxy-thiol polymerization under light irradiation. The remarkable photolatent characteristics demonstrate the significant potential in broadening the application of aryl glycine derivatives in controlled photopolymerization processes.