A mechanism for the effect of a surface-active element, namely Sb, on the bonding between an external oxide layer and a ferrous substrate was determined. It was found that Sb segregation at the ...external oxide/substrate interface resulted in decreased stability of the interfacial region. This was attributed to an increase in the atomic spacing near the interface in the Fe-xMn-0.03Sb (at%) alloys arising from Sb segregation, which led to the development of significant interfacial strains. The local strain reduced the energy required to separate the oxide from the metal matrix. HR-TEM revealed that this effect was intensified with increasing alloy Mn content, where the strain near the interface increased from 0.11 to 0.22 as the alloy Mn increased from 2 to 10 at.%. This was due to the higher bulk Mn content resulting in increased Sb segregation, which resulted in greater local strain in the interfacial region.
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Two identical layered metal–organic frameworks (MOFs) (CoFRS and NiFRS) are constructed by using flexible 1,10‐bis(1,2,4‐triazol‐1‐yl)decane as pillars and 1,4‐benzenedicarboxylic acid as rigid ...linkers. The single‐crystal structure analysis indicates that the as‐synthesized MOFs possess fluctuant 2D networks with large interlayer lattices. Serving as active electrode elements in supercapacitors, both MOFs deliver excellent rate capabilities, high capacities, and longstanding endurances. Moreover, the new intermediates in two electrodes before and after long‐lifespan cycling are also examined, which cannot be identified as metal hydroxides in the peer reports. After assembled into battery‐supercapacitor (BatCap) hybrid devices, the NiFRS//activated carbon (AC) device displays better electrochemical results in terms of gravimetric capacitance and cycling performance than CoFRS//AC devices, and a higher energy‐density value of 28.7 Wh kg−1 compared to other peer references with MOFs‐based electrodes. Furthermore, the possible factors to support the distinct performances are discussed and analyzed.
Flexible pillar‐supported layered metal–organic frameworks (MOFs) with non‐square interlayer pores, namely, CoFRS and NiFRS, are prepared and serve as active electrode elements in supercapacitors. After coupling them with activated carbon as negative electrodes, the hybrid NiFRS//activated carbon (AC) battery‐supercapacitor (BatCap) device delivers better electrochemical performances (i.e., capacity, energy density, and cycling life) than the CoFRS//AC device.
The morbidity, mortality, and burden of burn victims and patients with severe diabetic wounds are still high, which leads to an extensively growing demand for novel treatments with high clinical ...efficacy. Biomaterial-based wound treatment approaches have progressed over time from simple cotton wool dressings to advanced skin substitutes containing cells and growth factors; however, no wound care approach is yet completely satisfying. Bioactive glasses are materials with potential in many areas that exhibit unique features in biomedical applications. Today, bioactive glasses are not only amorphous solid structures that can be used as a substitute in hard tissue but also are promising materials for soft tissue regeneration and wound healing applications. Biologically active elements such as Ag, B, Ca, Ce, Co, Cu, Ga, Mg, Se, Sr, and Zn can be incorporated in glass networks; hence, the superiority of these multifunctional materials over current materials results from their ability to release multiple therapeutic ions in the wound environment, which target different stages of the wound healing process. Bioactive glasses and their dissolution products have high potency for inducing angiogenesis and exerting several biological impacts on cell functions, which are involved in wound healing and some other features that are valuable in wound healing applications, namely hemostatic and antibacterial properties. In this review, we focus on skin structure, the dynamic process of wound healing in injured skin, and existing wound care approaches. The basic concepts of bioactive glasses are reviewed to better understand the relationship between glass structure and its properties. We illustrate the active role of bioactive glasses in wound repair and regeneration. Finally, research studies that have used bioactive glasses in wound healing applications are summarized and the future trends in this field are elaborated.
Since the first demonstration, remarkable progress has been made in the theoretical analysis, structural design, numerical simulation, and potential applications of metamaterial absorbers (MAs). With ...the continuous advancement of novel materials and creative designs, the absorption of MAs is significantly improved over a wide frequency spectrum from microwaves to the optical regime. Further, the integration of active elements into the MA design allows the dynamical manipulation of electromagnetic waves, opening a new platform to push breakthroughs in metadevices. In the last several years, numerous efforts have been devoted to exploring innovative approaches for incorporating tunability to MAs, which is highly desirable because of the progressively increasing demand on designing versatile metadevices. Here, a comprehensive and systematical overview of active MAs with adaptive and on‐demand manner is presented, highlighting innovative materials and unique strategies to precisely control the electromagnetic response. In addition to the mainstream method by manipulating periodic patterns, two additional approaches, including tailoring dielectric spacer and transforming overall structure are called back. Following this, key parameters, such as operating frequency, relative tuning range, and switching speed are summarized and compared to guide for optimum design. Finally, potential opportunities in the development of active MAs are discussed.
Metamaterial absorbers (MAs), designed using artificial subwavelength structures, feature low profile and unique absorption. Employing active components into the element designs facilitate multifunction and miniaturization of MAs. A comprehensive and systematical review covering the work essentially conducted in the domain of cutting‐edge active MAs is presented, highlighting innovative materials and unique strategies to manipulate electromagnetic response at frequencies up to optical regions.
In order to investigate the influence of the surface-active element on the interfacial phenomena between molten iron and molten Al
2
O
3
-CaO-SiO
2
slag, a mildly surface-active element, nitrogen, ...was introduced, and the interfacial phenomena were directly observed using an X-ray sessile drop method. The multiphysics model was employed to calculate the velocity of the Marangoni convection caused by the surface/interfacial tension gradient along with the contour of the sessile drop. Movement of the sessile drop was observed in the experiment, and the driving force of the movement was discussed from the distribution of surface tension active element viewpoint. The calculated velocity of the Marangoni convection in the droplet was reasonably agreed with the literature data for the metal-gas system, and thus, the same model was applied for the metal-slag system. The velocity of the Marangoni convection for the metal-slag system becomes ten times lower compared to that of metal-gas system.
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The active elements play key roles in the soldering of SiO2 glasses using Sn-based solders. In this study, the influence of Lu, La and Ga active atoms on the Sn/SiO2 interfacial bonding property is ...investigated by first principle calculation systematically. We built the β-Sn(011)/SiO2(0001) interface with low lattice mismatch firstly, and different terminations or stacking sequences are considered. The Wad (work of adhesion) was calculated to evaluate the mechanical properties of the interface. The O-T interface with O bridge site has the largest Wad of 3.84 J/m2. With the doping of Lu and La atoms at the interface, the Wad values of interfaces increase to 5.52 J/m2 and 5.29 J/m2. The negative values of ΔGseg (heat of segregation) suggest that doping Lu and La atoms at the interface is stable in thermodynamics. While doping Ga is not stable in thermodynamics. The electronic structures were studied by the methods of charge density difference and partial density of states. The results show that the Lu-O and La-O bonds are all ionic-covalent bonds, but with more covalent composition comparing to the Sn-O bond. In conclusions, Lu and La active atoms can improve the bonding properties of the Sn/SiO2 interface.
Trace elements (metals, transition elements and non-metals) are an essential component of the human body's functionality. These trace elements include Fe, Mn, Li, Al, Co, Ni, Cu, Ag, Se, As, Cr, V, ...Zn, Cs, U and others. In general, it is believed that about 25 chemical elements are important for the normal functioning of the human body. Trace elements in fresh drinking water as a biological component remain outside the attention of specialists in the field of therapeutic water. Of course, the content of biologically active trace elements in drinking water is much lower than in therapeutic mineral waters, but it should be taken into account that the amount of drinking water consumed by a person is much higher than that of mineral water during therapy. In this case, the low concentration of biologically active trace elements in drinking water is compensated for by the large amount of this water consumed every day. This can have a certain therapeutic effect. The paper presents the results of an assessment of the possible biologically active effect of domestic fresh water. The research was carried out in the most common and widely used aquifers – the groundwater and Buchak aquifers, which are the first to surface and are most widely exploited in rural and suburban areas. The studies were performed in 6 settlements of the Kyiv region: Hlevakha, Novoselivka, Olenivka, Baryshivka, Sezenkiv, and Liutizh. The analyses were performed using an ICP-MS Element 2 inductively coupled plasma mass spectrometer at the Institute of Geochemistry, Mineralogy and Ore Formation of the National Academy of Sciences of Ukraine. The presence of Fe, Mn, Li, Al, Co, Ni, Cu, Ag, Se, As, which are biologically active trace elements, was determined in the waters of the Quaternary sediments and in the waters of the Buchak aquifer complex. In addition, these waters contain Cr, V, Zn, Cs, U, which do not have medicinal effects but are important for the normal functioning of the human body. Although only 6 locations in the Kyiv region were examined, the results obtained are sufficient for preliminary conclusions that provide reasons to justify a new direction – biological aspects of domestic groundwater.
Due to the fast development of wireless communication technology, reconfigurable antennas with multimode and cognitive radio operation in modern wireless applications with a high-data rate have drawn ...very close attention from researchers. Reconfigurable antennas can provide various functions in operating frequency, beam pattern, polarization, etc. The dynamic tuning can be achieved by manipulating a certain switching mechanism through controlling electronic, mechanical, physical or optical switches. Among them, electronic switches are the most popular in constituting reconfigurable antennas due to their efficiency, reliability and ease of integrating with microwave circuitry. In this paper, we review different implementation techniques for reconfigurable antennas. Different types of effective implementation techniques have been investigated to be used in various wireless communication systems such as satellite, multiple-input multiple-output (MIMO), mobile terminals and cognitive radio communications. Characteristics and fundamental properties of the reconfigurable antennas are investigated.
Functionally graded materials (FGMs) with site specific chemical composition are commonly manufactured by directed energy deposition (DED). Although previous work fabricated an FGM with a ...compositional variation between a ferritic and austenitic alloy, difficulties arose due to variations in deposit shape with composition change. This problem also occurs for FGMs in literature; however, unlike other cases, the thermophysical properties of these two alloys were similar throughout the build. Here, we investigate the role of chemical composition and surface-active elements on deposit geometry during the manufacture of FGMs by laser DED. Single-track experiments for the relevant FGM compositions are analyzed with results from a well-tested, three-dimensional, transient numerical heat transfer and fluid flow model and thermodynamic calculations. Experiments showed deposit shape varied as a function of composition for constant laser power and scan speed. Thermodynamic analysis indicated that the oxygen solubility in the fusion zone varied significantly for each composition used for the FGM. Numerical modeling revealed that the change in fluid flow caused by Marangoni convection due to dissolved oxygen in the fusion zone were mainly responsible for the changes in deposit shape observed in experiments. Finally, because oxygen can be introduced into the fusion zone through the feedstock as well as the surrounding atmosphere, these findings elucidate a previously unconsidered aspect of process control during DED fabrication of FGMs.
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