This paper reviews recent progress of portable short-range noncontact microwave radar systems for motion detection, positioning, and imaging applications. With the continuous advancements of modern ...semiconductor technologies and embedded computing, many functionalities that could only be achieved by bulky radar systems in the past are now integrated into portable devices with integrated circuit chips and printed circuits boards. These portable solutions are able to provide high motion detection sensitivity, excellent signal-to-noise ratio, and satisfactory range detection capability. Assisted by on-board signal processing algorithms, they can play important roles in various areas, such as health and elderly care, veterinary monitoring, human-computer interaction, structural monitoring, indoor tracking, and wind engineering. This paper reviews some system architectures and practical implementations for typical wireless sensing applications. It also discusses potential future developments for the next-generation portable smart radar systems.
Precise control of solid-state elastic waves' mode content and coherence is of great use nowadays in reinforcing mechanical energy harvesting/storage, nondestructive material testing, wave-matter ...interaction, high sensitivity sensing, and information processing, etc. Its efficacy is highly dependent on having elastic transmission channels with lower loss and higher degree of freedom. Here, we demonstrate experimentally an elastic analog of the quantum spin Hall effects in a monolithically scalable configuration, which opens up a route in manipulating elastic waves represented by elastic pseudospins with spin-momentum locking. Their unique features including robustness and negligible propagation loss may enhance elastic planar-integrated circuit-level and system-level performance. Our approach promotes topological materials that can interact with solid-state phonons in both static and time-dependent regimes. It thus can be immediately applied to multifarious chip-scale topological phononic devices, such as path-arbitrary elastic wave-guiding, elastic splitters and elastic resonators with high-quality factors.
The acclimation rate of physiological functions that bear fitness costs under a changing environment is key to making predictions for fish, yet this has seldom been investigated. This study aimed to ...test whether there were different responses when different physiological functions reached steady states and to determine possible relationships with metabolic constraints during temperature changes in fish. Qingbo (Spinibarbus sinensis), a common cyprinid in southern China, was first pre-acclimated at either high (25 °C) or low (15 °C) temperature for eight weeks and assumed to be at thermal equilibrium. Then, the temperature was reversed, that is, the temperature was decreased from 25 °C to 15 °C in one group, defined as the cooling group, whereas the temperature of the other group was increased from 15 °C to 25 °C, defined as the warming group. The thermal tolerance, swimming performance and feeding metabolism were measured before temperature reversal as well as 1, 2, 4 and 8 weeks. The growth performance was also measured after the temperature reversal. Typical thermal compensation was suggested by a stronger heat tolerance, faster swimming speed and higher postprandial metabolic response in those acclimated at 25 °C than in those acclimated at 15 °C before temperature reversal. Cold tolerance suggested by the critical minimal temperature (CTmin) of the cooling group reached a thermal steady state within one week, whereas the adjustment of heat tolerance to the temperature increase indicated by the critical maximum temperature (CTmax) was much slower, reaching a steady state two weeks after the temperature reversal. The high flexibility of the standard metabolic rate as well as the postprandial metabolism and relatively lower feeding metabolism demonstrated that there were negligible effects at the aerobic scope for other physiological functions during digestion in qingbo, even during the temperature acclimation period. However, there was a slower adjustment of the swimming performance with the temperature decrease, which parallels the change of metabolic capacity. Furthermore, both the cooling and warming treatments had negative effects on growth performance, with the former mainly occurring through extra energy expenditure, whereas the latter mainly occurred through decreased feeding. It suggested that the slow adjustment of heat tolerance after the temperature increase compared to that of cold tolerance might be a challenge for cyprinids distributed in southern China. Furthermore, the decreased metabolic scope and hence swimming performance after the temperature decrease might have a fitness cost in qingbo and possibly other cyprinids in China.
•The thermal tolerance, swimming performance and growth performance were measured during temperature acclimation in a cyprinid species.•Both the temperature decrease and temperature increase treatments had negative effects on growth performance, with the former mainly occurring through extra energy expenditure, whereas the latter mainly occurred through decreased feeding rate.•The slow adjustment of heat tolerance after the temperature increase compared to that of cold tolerance might be a challenge for cyprinids distributed in southern China.•The decreased metabolic scope and hence swimming performance after the temperature decrease might have a fitness cost in qingbo.
B7‐H3 (CD276), a newly identified member of the B7 family of molecules, is often induced in human tumors and its overexpression is closely correlated with survival, prognosis or tumor grade. Although ...cancer immunotherapy has not been completely translated into clinical successes, interest has been further enhanced by the realization of these costimulatory molecules' potential as targets to modulate clinical immune responses. Despite ample evidence implicating B7‐H3 in tumor immune escape, a steady flow of reports have suggested that it may also have antitumor effects under certain circumstances. The safety and efficacy of targeting B7‐H3 with a monoclonal antibody for the treatment of advanced‐stage central nervous system cancer in children has been proven, making B7‐H3 an attractive therapeutic target for this kind of tumor. In addition, B7‐H3 was shown to promote invasion and accelerate carcinogenesis in tumor progression according to its nonimmunological regulatory roles. In this review, we discuss current understanding of the diverse functions of B7‐H3 in carcinogenesis and cancer progression, and consider future directions for designing cancer immunotherapeutic agents targeting B7‐H3.
Stable and efficient guided waves are essential for information transmission and processing. Recently, topological valley-contrasting materials in condensed matter systems have been revealed as ...promising infrastructures for guiding classical waves, for they can provide broadband, non-dispersive and reflection-free electromagnetic/mechanical wave transport with a high degree of freedom. In this work, by designing and manufacturing miniaturized phononic crystals on a semi-infinite substrate, we experimentally realized a valley-locked edge transport for surface acoustic waves (SAWs). Critically, original one-dimensional edge transports could be extended to quasi-two-dimensional ones by doping SAW Dirac "semimetal" layers at the boundaries. We demonstrate that SAWs in the extended topological valley-locked edges are robust against bending and wavelength-scaled defects. Also, this mechanism is configurable and robust depending on the doping, offering various on-chip acoustic manipulation, e.g., SAW routing, focusing, splitting, and converging, all flexible and high-flow. This work may promote future hybrid phononic circuits for acoustic information processing, sensing, and manipulation.
Many constitutive models have been proposed to describe the mechanical behavior of cemented soil at large strains (above 1%). Less attention has been paid to the highly nonlinear stress–strain ...behavior at small strains, which are important for accurately analyzing the serviceability of many infrastructures. In this study, a bounding surface model was developed to simulate cemented soil behavior from small to large strains. Some new formulations were proposed to improve the modeling of small-strain behavior, including (1) the elastic shear modulus over a wide range of stress conditions, and (2) the nonlinear degradation of bonding strength (pb) with damage strain (εd) in the lnpb−εd plane. The new model was applied to simulate drained and undrained triaxial tests on cemented soils at different cement contents and confining pressures. Comparisons between the measured and computed results show that the new model can well capture many important aspects of cemented soil behavior, especially the elastic shear modulus at very small strains and stiffness degradation at small strains. Furthermore, the model gives a good simulation of strain softening/hardening and dilatancy/contraction during shearing under various confining pressure and void ratio conditions.
For noncontact vital sign monitoring by using a continuous-wave (CW) radar, the quadrature cosine transform (QCT) with varying window length (VWL) technique is proposed in this article for the first ...time. The novel algorithm can directly yield the vibration frequency of the radar's output IQ signals with multiple advantages, including the elimination of dc offset calibration and mitigation of nonlinear interferences caused by harmonic and intermodulation terms, and there is a 50% reduction in frequency resolution of the conventional Fourier transform (FT) that is commonly utilized in existing articles. Thus, it can strike a balance between accuracy and computational efficiency with a short window length. The excellent performance was demonstrated by both theoretical predictions and simulation results. Experiments involving a participant seated 1 m away from the 2.4-GHz ISM band radar prototype demonstrated that the proposed algorithm measures the respiratory rate variability (RRV) and short-time heart rate (HR) with respective errors of less than 1% and 3%. Moreover, the proposed algorithm was more accurate than conventional methods with various window lengths (3-27 s) in 10-min noncontact experiments to monitor the vital signs of ten participants.
A new accurate formula for the extended Woodward UV rules for all possible eight structures of α,β‐unsaturated ketones, λmax = 212.82 + 11.37Nsub + 4.79Nexo, was discovered by solving 56 ordered ...triples using Microsoft Excel's inverse matrix method, with an overall 99.9% accuracy between the observed and calculated maxima values. This discovered formula and these eight unique data points can be illustrated in the linear‐equation plane or visualized in the three‐dimensional graphics using computer software.
The Woodward UV Rules are extended from the original 5 selected structures to the all possible 8 structures of conjugated ketones. A new accurate mathematical formula is discovered by solving 56 ordered triples via the inverse matrix method. The 8 unique absorption maxima are illustrated and visualized in the 3‐dimensional Woodward UV plane using computer software.The Woodward UV Rules are extended from the original 5 selected structures to the all possible 8 structures of conjugated ketones. A new accurate mathematical formula is discovered by solving 56 ordered triples via the inverse matrix method. The 8 unique absorption maxima are illustrated and visualized in the 3‐dimensional Woodward UV plane using computer software.
This paper presents a novel self-injection-locked radar with two antennas to transmit and retransmit a continuous wave to opposite sides of a human body for monitoring vital signs in real time with ...large body movements. The system can prevent the nonlinear effects of large Doppler phase shifts on the cancellation of body motion artifacts, to extract accurate vital signs from the received Doppler-shifted signal. However, the effectiveness of the cancellation is limited by the received clutter echoes in this system. Therefore, the system also has a clutter effect elimination circuit to improve substantially the detection of vital signs in an examinee at various positions between the two antennas even when the examinee moves often by more than one wavelength.
Abstract
Two kinds of Al‐based metal‐organic frameworks (Al‐MOFs), MIL‐53(Al), and MIL‐96(Al), were synthesized by the solvothermal method and then characterized using SEM, XRD, and FTIR. The Al‐MOFs ...and halloysite nanotubes (HNTs) were blended and added to silicone rubber foams (SiFs). The mechanical properties and flame retardancy of the composites were tested and analyzed using universal tensile tester, limiting oxygen index (LOI), vertical combustion tester, cone calorimeter, TG, SEM, EDS, and FTIR. The results show that Al‐MOFs synthesized by the solvothermal method have high crystallinity and purity. Compared with pure SiFs, the LOI of SiFs with 2 wt% MIL‐53(Al) and 2 wt% HNTs increased to 29.4%, while total heat release and total smoke release decreased by 36.9% and 32.4%. The flame retardant mechanism of the composites is mainly reflected in the condensed phase. MIL‐53(Al) and HNTs can synergistically promote the formation of a dense carbon layer, blocking heat and oxygen from entering the SiFs matrix.
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