Hierarchically nanostructured porous hollow microspheres of hydroxyapatite (HAP) are a promising biomaterial, owing to their excellent biocompatibility and porous hollow structure. Traditionally, ...synthetic hydroxyapatite is prepared by using an inorganic phosphorus source. Herein, we report a new strategy for the rapid, sustainable synthesis of HAP hierarchically nanostructured porous hollow microspheres by using creatine phosphate disodium salt as an organic phosphorus source in aqueous solution through a microwave‐assisted hydrothermal method. The as‐obtained products are characterized by powder X‐ray diffraction (XRD), Fourier‐transform IR (FTIR) spectroscopy, SEM, TEM, Brunauer–Emmett–Teller (BET) nitrogen sorptometry, dynamic light scattering (DLS), and thermogravimetric analysis (TGA). SEM and TEM micrographs show that HAP hierarchically nanostructured porous hollow microspheres consist of HAP nanosheets or nanorods as the building blocks and DLS measurements show that the diameters of HAP hollow microspheres are within the range 0.8–1.5 μm. The specific surface area and average pore size of the HAP porous hollow microspheres are 87.3 m2g−1 and 20.6 nm, respectively. The important role of creatine phosphate disodium salt and the influence of the experimental conditions on the products were systematically investigated. This method is facile, rapid, surfactant‐free and environmentally friendly. The as‐prepared HAP porous hollow microspheres show a relatively high drug‐loading capacity and protein‐adsorption ability, as well as sustained drug and protein release, by using ibuprofen as a model drug and hemoglobin (Hb) as a model protein, respectively. These experiments indicate that the as‐prepared HAP porous hollow microspheres are promising for applications in biomedical fields, such as drug delivery and protein adsorption.
Sleepy hollow: Hydroxyapatite (HAP) microspheres were synthesized from creatine phosphate as a biocompatible phosphorus source (see figure). As‐prepared nanostructured porous hollow microspheres show relatively high drug‐loading and high protein‐adsorption capacity.
The first Special Sensor Microwave Imager/Sounder (SSMIS) was launched in October 2003 aboard the Air Force Defense Meteorological Satellite Program (DMSP) F-16 Spacecraft. As originally conceived, ...the SSMIS integrates the imaging capabilities of the heritage DMSP conically scanning Special Sensor Microwave/Imager sensor with the cross-track microwave sounders Special Sensor Microwave Temperature and Special Sensor Microwave Humidity Sounder, SSM/T-2 into a single conically scanning 24-channel instrument with extended sounding capability to profile the mesosphere. As such, the SSMIS represents the most complex operational satellite passive microwave imager/sounding sensor flown while, at the same time, offering new and challenging capabilities associated with radiometer channels having common fields of view, uniform polarizations, and fixed spatial resolutions across the active scene scan sector. A comprehensive end-to-end calibration/validation (cal/val) of the first SSMIS initiated shortly after launch was conducted under joint sponsorship by the DMSP and the Navy Space and Warfare Systems Command. Herein, we provide an overview of the SSMIS instrument design, performance characteristics, and major cal/val results. Overall, the first SSMIS instrument exhibits remarkably stable radiometer sensitivities, meeting requirements with considerable margin while providing high-quality imagery for all channels. Two unanticipated radiometer calibration anomalies uncovered during the cal/val-sun intrusion into the warm-load calibration target and antenna reflector emissions-required significant attention during the cal/val program. In particular, the tasks of diagnosing the root cause(s) of these anomalies as well as the development of ground processing software algorithms to mitigate their impact on F-16 SSMIS and hardware fixes on future instruments necessitated the construction of extensive analysis and simulation tools. The lessons learned from the SSMIS cal/val and the associated analysis tools are expected to play an important role in the design and performance evaluation of future passive microwave imaging and sounding instruments as well as guiding the planning and development of future cal/val programs.
Accessing subwavelength information about a scene from the far-field without invasive near-field manipulations is a fundamental challenge in wave engineering. Yet it is well understood that the dwell ...time of waves in complex media sets the scale for the waves' sensitivity to perturbations. Modern coded-aperture imagers leverage the degrees of freedom (d.o.f.) offered by complex media as natural multiplexor but do not recognize and reap the fundamental difference between placing the object of interest outside or within the complex medium. Here, we show that the precision of localizing a subwavelength object can be improved by several orders of magnitude simply by enclosing it in its far field with a reverberant passive chaotic cavity. We identify deep learning as a suitable noise-robust tool to extract subwavelength localization information encoded in multiplexed measurements, achieving resolutions well beyond those available in the training data. We demonstrate our finding in the microwave domain: harnessing the configurational d.o.f. of a simple programmable metasurface, we localize a subwavelength object along a curved trajectory inside a chaotic cavity with a resolution of λ/76 using intensity-only single-frequency single-pixel measurements. Our results may have important applications in photoacoustic imaging as well as human-machine interaction based on reverberating elastic waves, sound, or microwaves.
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Heating plays a vital role in science, engineering, mining, and space, where heating can be achieved via electrical, induction, infrared, or microwave radiation. For fast switching and continuous ...applications, hotplate or Peltier elements can be employed. However, due to bulkiness, they are ineffective for portable applications or operation at remote locations. Miniaturization of heaters reduces power consumption and bulkiness, enhances the thermal response, and integrates with several sensors or microfluidic chips. The microheater has a thickness of ~ 100 nm to ~ 100 μm and offers a temperature range up to 1900℃ with precise control. In recent years, due to the escalating demand for flexible electronics, thin-film microheaters have emerged as an imperative research area. This review provides an overview of recent advancements in microheater as well as analyses different microheater designs, materials, fabrication, and temperature control. In addition, the applications of microheaters in gas sensing, biological, and electrical and mechanical sectors are emphasized. Moreover, the maximum temperature, voltage, power consumption, response time, and heating rate of each microheater are tabulated. Finally, we addressed the specific key considerations for designing and fabricating a microheater as well as the importance of microheater integration in COVID-19 diagnostic kits. This review thereby provides general guidelines to researchers to integrate microheater in micro-electromechanical systems (MEMS), which may pave the way for developing rapid and large-scale SARS-CoV-2 diagnostic kits in resource-constrained clinical or home-based environments.
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Microwave-enhanced pyrolysis of algae produced more hydrocarbons under H2 atmosphere, while more carboxylic acids were generated under CO2 atmosphere. Display omitted
•Microwave-enhanced pyrolysis of ...algae produced bio-oil with HHV of 34MJ/kg.•The energy yield was 236.9% under 10% H2/Ar atmosphere.•Microwave assisted the catalytic performance of activated carbon in H2.•Plenty of carboxylic acids (66.6%) were formed under CO2 atmosphere.
Microwave-enhanced pyrolysis (MEP) of natural algae under different reaction conditions was carried out. The optimal conditions for bio-oil production were the following: algae particle size of 20-5 mesh, microwave power of 600W, and 10% of activated carbon as microwave absorber and catalyst. The maximum liquid yield obtained under N2, 10% H2/Ar, and CO2 atmosphere was 49.1%, 51.7%, and 54.3% respectively. The energy yield of bio-products was 216.7%, 236.9% and 208.7% respectively. More long chain fatty acids were converted into hydrocarbons by hydrodeoxygenation under 10% H2/Ar atmosphere assisted by microwave over activated carbon containing small amounts of metals. Under CO2 atmosphere, carboxylic acids (66.6%) were the main products in bio-oil because the existence of CO2 vastly inhibited the decarboxylation. The MEP of algae was quick and efficient for bio-oil production, which provided a way to not only ameliorate the environment but also obtain fuel or chemicals at the same time.
Presented are design considerations for a potential detection and measurement technique that could provide operational awareness of high power microwave (HPM) directed energy weapon exposure for ...force health protection applications, leveraging thermoacoustic (TA) wave generation as the field interaction mechanism. The HPM electromagnetic frequency (EMF) regime, used in applications in both the counter-materiel and non-lethal counter-personnel design space, presents real-time personnel exposure warning challenges due to the potentially wide variation in time and frequency domain characteristics of the incident beam. As with other EM-thermal interactions, the thermoacoustic wave effect provides the potential to determine EM energy and power deposition without the need to measure ambient field intensity values or overload-sensitive EMF survey equipment. Following measurement of relevant EM, thermal, and elastic material property values, a carbon-filled polytetrafluoroethylene (CF-PTFE) lossy dielectric medium subject to pulsed HPM was computationally modeled using the commercial finite element method multi-physics simulation software package COMSOL. The simulation was used to explore the impacts of various material properties on TA signal output as a function of simulated incident field power density, EM frequency, and pulse length, thereby informing the selection of system components for the further development of a full TA-based HPM detection chain.
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•Both physisorption and chemisorption of Hg0 occurred on the surface of M6WN5.•Chemisorption process was an absolute predominant route for Hg0 removal by M6WN5.•The effect of NO, H2O, ...SO2 and O2 on Hg0 removal by M6WN5 was investigated.•M6WN5 demonstrated to be a promising Hg0 sorbent in flue gas.
Pyrolyzed biochars from an industrial medicinal residue waste were modified by microwave activation and NH4Cl impregnation. Mercury adsorption of different modified biochars was investigated in a quartz fixed-bed reactor. The results indicated that both physisorption and chemisorption of Hg0 occurred on the surface of M6WN5 which was modified both microwave and 5wt.% NH4Cl loading, and exothermic chemisorption process was a dominant route for Hg0 removal. Microwave activation improved pore properties and NH4Cl impregnation introduced good active sites for biochars. The presence of NO and O2 increased Hg0 adsorption whereas H2O inhibited Hg0 adsorption greatly. A converse effect of SO2 was observed on Hg0 removal, namely, low concentration of SO2 promoted Hg0 removal obviously whereas high concentration of SO2 suppressed Hg0 removal. The Hg0 removal by M6WN5 was mainly due to the reaction of the CCl with Hg0 to form HgCl2, and the active state of CCl* groups might be an intermediate group in this process. Thermodynamic analysis showed that mercury adsorption by the biochars was exothermic process and apparent adsorption energy was 43.3kJ/mol in the range of chemisorption. In spite of low specific surface area, M6WN5 proved to be a promising Hg0 sorbent in flue gas when compared with other sorbents.
•Microwave pretreatment effect on the content of phenolic compounds studied.•The degradation of phenolics during storage displayed pseudo first-order kinetics.•Initial concentration of the phenolics ...affects on their degradation rate during storage.
Storage stability and degradation kinetics of phenolic compounds in rapeseed oil pressed from microwave treated seeds (0, 2, 4, 6, 8, 10min, 800W) during long-term storage (12months) at a temperature of 20°C was discussed in the current study. The dominant phenolic compound detected in rapeseed oil was canolol, followed by minor amounts of free phenolic acids and sinapine. The most pronounced effect of seeds microwaving was noted for canolol formation – after 10-min exposure the quantity of this compound was approximately 63-fold higher than in control oil. The degradation of phenolics during storage displayed pseudo first-order kinetics. Differences in the initial degradation rate (r0) demonstrated significant impact of the period of seeds microwave exposure on the degradation rates of phenolic compounds. Results of the half-life calculation (t1/2) showed that the storage stability of phenolic compounds was higher in oils produced from microwave treated rapeseeds than in control oil.
Research efforts addressing spin waves (magnons) in microand nanostructured ferromagnetic materials have increased tremendously in recent years. Corresponding experimental and theoretical work in ...magnonics faces significant challenges in that spinwave dispersion relations are highly anisotropic and different magnetic states might be realized via, for example, the magnetic field history. At the same time, these features offer novel opportunities for wave control in solids going beyond photonics and plasmonics. In this topical review we address materials with a periodic modulation of magnetic parameters that give rise to artificially tailored band structures and allow unprecedented control of spin waves. In particular, we discuss recent achievements and perspectives of reconfigurable magnonic devices for which band structures can be reprogrammed during operation. Such characteristics might be useful for multifunctional microwave and logic devices operating over a broad frequency regime on either the macroor nanoscale.
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