A large variety of degeneracy exist in both static and dynamic regimes in anisotropic elastic media. Extraordinary degeneracies occur mostly in the static regime and they are of great importance in ...understanding the existence of the so-called space of degeneracy in the dynamic regime. This paper deals with the interconnection between degeneracies in the static and dynamic regimes. Both the modified Lekhnitskii formalism and the Stroh formalism are employed in exploring the degeneracies in the transversely isotropic media. It is demonstrated that the space of degeneracy can be regarded as an extension of the static degeneracy, and the development of the static extraordinary degeneracy into the dynamic regime is via a number of spaces of degeneracy of various types. The static degeneracy can also span a space of degeneracy.
A switchable single‐wideband (SWB)‐to‐dual‐wideband (DWB) bandpass filter (BPF), which is realized by using lumped switches, is presented in this paper. By alternating the operation modes—ON and ...OFF—in which the ON mode is achieved by placing the capacitors at the switching spots and the OFF mode is achieved by replacing the capacitors with inductors, DWB‐to‐SWB BPF can be achieved on the same device. In addition, by changing the capacitor values, the center frequency (CF) of the lower passband of DWB BPF can be easily tuned from 1.69 GHz to 2.22 GHz, while the higher passband stays almost unchanged. As an example, an SWB‐to‐DWB BPF is designed, fabricated, and measured. This BPF exhibits good performance including wideband, high isolation, compact size, and ability to switch.
A surface acoustic wave (SAW) relative humidity (RH) sensor based on graphene oxide (GO)/TiO2 composite sensitive film was prepared. A uniform TiO2 film was deposited on the surface of a SAW ...resonator by DC reaction sputtering to get a TiO2/SAW sensor. The GO was coated onto the TiO2/SAW by drop-coated to construct the GO/TiO2/SAW sensor. The large specific surface area, abundant hydrophilic functional groups, and highly stable structure of the GO/TiO2 sensitive film are benefit to the improvement of the sensor performances. The prepared GO/TiO2/SAW sensor demonstrated excellent sensitive performances for practical applications, including high sensitivity, fast response and recovery, good repeatability, and good stability.
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•SAW relative humidity sensor with GO/TiO2 sensitive film is proposed.•SAW sensor exhibits high response to RH, good repeatability and long-time stability.•GO/TiO2 shows large specific surface area and abundant hydrophilic functional groups.
A delay line configuration Rayleigh SAW immunosensor with an Au-nanoparticles-decorated graphene (AuNPs-Gr) fluidic channel is proposed for the detection of CA125. The tube composed of Gr sheets is ...prepared by chemical vapor deposition (CVD) and Au-nanoparticles are decorated on the inner wall of the Gr tube by electrodeposition method. The AuNPs-Gr tube with a volume of 4.8 μL is placed on the bus bar of the SAW device and acts as sensing element as well as a micro-fluidic chamber. To estimate the sensing performances of the immunosensor comprehensively, besides the amplitude-frequency characteristics of the insert loss (S21), the phase-frequency characteristics of S21, the equivalent conductance-frequency and susceptance-frequency characteristics are also analyzed. The deposition time of the Gr tubes, antibody concentration, antibody incubation time, and antigen incubation time are optimized to enhance the response of the SAW biosensor. Although the response sensitivity extracted from the amplitude-frequency curves (8.57 Hz/log(mU/mL)) is a bit lower than that from phase-frequency data (11.88 Hz/log(mU/mL)) and that from susceptance-frequency data (12.14 Hz/log(mU/mL)), a wider linear response range of 0.01–300 mU/mL is obtained from the amplitude-frequency curves and the limit of detection is calculated to be 0.00371 mU/mL. In addition, the proposed AuNPs-Gr fluidic channel SAW immunosensor exhibits good specificity and long-time stability and can be used to detect the CA125 in human serum.
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•SAW CA125 immunosensor with AuNPs-Gr fluidic channel is proposed.•S21 amplitude and phase, complex impedance vs. frequency are analyzed.•Wide linear range of 0.01–300 mU/mL is obtained from the amplitude-frequency data.•The immunosensor exhibits good specificity, long-time stability and recovery in serum.
A microwave relative humidity (RH) sensor based on shorted split ring resonator with interdigital capacitance (SSRR-IDC) as a test platform and α-Al2O3 nanoflakes/chitosan (CS) composite as sensitive ...film is proposed for the detection of human respiration. The SSRR-IDC was designed by optimizing the finger spacing and width of the IDC. Electromagnetic simulation of the designed SSRR-IDC confirms a strong electric field distribution and high dielectric sensitivity in the IDC region. The porous α-Al2O3 nanoflakes/CS composite was coated onto the IDC region of the SSRR to obtain a microwave humidity sensor. Abundant hydrophilic groups and large specific surface area of the α-Al2O3 nanoflakes/CS contribute to the adsorption of water molecules. The proposed microwave humidity sensor shows excellent sensitivity in wide RH range, especially at high humidity condition. The working principle and the sensitivity enhancement mechanism of the proposed microwave sensor were explained by combining a circuit model analysis and the dielectric property and surface microstructure changes of the sensitive materials. Furthermore, the microwave sensor also demonstrates short response/recover time and outstanding repeatability, long-term stability, temperature stability, and selectivity. Additionally, the prepared microwave humidity sensor successfully records respiratory data from different volunteers. Changes in respiratory depth before and after drinking water of the volunteers can also be distinguished by this sensor.
•A SSRR-IDC was designed as a humidity sensing platform.•Porous α-Al2O3 nanoflakes/CS composite was prepared on the IDC as sensitive film.•Humidity sensor exhibits high sensitivity and fast response/recovery.•Human respiratory monitoring is achieved using the proposed humidity sensor.
Atherosclerosis (AS) is a chronic progressive disease caused by various factors and causes various cerebrovascular and cardiovascular diseases (CVDs). Reducing the plasma levels of low-density ...lipoprotein cholesterol is the primary goal in preventing and treating AS. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a crucial role in regulating low-density lipoprotein cholesterol metabolism. Panax notoginseng has potent lipid-reducing effects and protects against CVDs, and its saponins induce vascular dilatation, inhibit thrombus formation, and are used in treating CVDs. However, the anti-AS effect of the secondary metabolite, 20( S )-protopanaxatriol (20( S )-PPT), remains unclear. In this study, the anti-AS effect and molecular mechanism of 20( S )-PPT were investigated in vivo and in vitro by Western blotting, real-time polymerase chain reaction, enzyme-linked immunosorbent assay, immunofluorescence staining, and other assays. The in vitro experiments revealed that 20( S )-PPT reduced the levels of PCSK9 in the supernatant of HepG2 cells, upregulated low-density lipoprotein receptor protein levels, promoted low-density lipoprotein uptake by HepG2 cells, and reduced PCSK9 mRNA transcription by upregulating the levels of forkhead box O3 protein and mRNA and decreasing the levels of HNF1α and SREBP2 protein and mRNA. The in vivo experiments revealed that 20( S )-PPT upregulated aortic α-smooth muscle actin expression, increased the stability of atherosclerotic plaques, and reduced aortic plaque formation induced by a high-cholesterol diet in ApoE −/− mice (high-cholesterol diet-fed group). Additionally, 20( S )-PPT reduced the aortic expression of CD68, reduced inflammation in the aortic root, and alleviated the hepatic lesions in the high-cholesterol diet-fed group. The study revealed that 20( S )-PPT inhibited low-density lipoprotein receptor degradation via PCSK9 to alleviate AS.
Superhydrophobic surfaces that are durable and can be easily manufactured are of high interest for many industrial applications. Measuring and understanding roughness in the context of ...superhydrophobicity is the first step in creation of a surface that does not require activation to be hydrophobic. In this study, the as sprayed surface of different cermet (WC-10Co4Cr and Cr3C2-25Ni20Cr) coatings produced by High Velocity Air Fuel (HVAF) spraying – have been investigated to assess their wetting ability. In order to address the challenges raised by the specific roughness profile of thermal spray surfaces, two routes have been adapted and used for surface characteristics analysis i.e. statistical and fractal. Results show that both methods have a strong correlation to wettability. Roughness parameters Sdq and Sdr show good correlation with advancing contact angle. Hausdorff Dimension of a sub-micrometer profile shows good relation with the contact angle and provides information for state of the droplet. To determine how to increase the contact angle of the coating surface, coating parameters such as CGS Density have been correlated with Hausdorff Dimension. Both methods provide good understanding in terms of wettability of rough cermet surfaces.
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•High performance cermet coatings produced by High Velocity Air Fuel Spraying.•Hydrophobic properties of the coatings without surface activation•Roughness – wettability correlations by statistical analysis and fractal analysis•Wetting characteristics predictability
Two-dimensional ternary locally resonant phononic crystals can be used for vibration control and noise insulation in the low (even audible) frequency range. They traditionally consist of cylindrical ...scatterers with uniform coatings in their exterior. An alternative coating profile with a comblike profile is proposed and investigated in this paper. The band structures are calculated using the finite element method. We find that a complete bandgap can be induced at a significantly low frequency, the wavelength of which is more than 20 times the lattice constant. The mechanism for such a change is suggested using an equivalent spring-mass model and analyzing the eigenmodes at the bandgap edges. Numerical results and the results predicted by the spring-mass model are coherent.
A surface acoustic wave (SAW) relative humidity (RH) sensor based on flake-like nanodiamond-chitosan (ND-CS) composite film was prepared. Flake-like NDs were uniformly dispersed into the CS and ...combined with the CS by hydrogen bonding. The abundant hydrophilic groups of both ND and CS are beneficial for the adsorption of water molecules. The obtained humidity sensor exhibits good linear response under wide RH range of 10%-90% with a tiny humidity hysteresis of 3.9%. The sensitivity of the sensor is -4.93 kHz/% for the adsorption process and -4.83 kHz/% for the desorption process. Short response time of 17.6 s and recovery time of 5.2 s are obtained when the RH switches between 10% and 70%. Meanwhile, the prepared ND-CS coated SAW sensor also shows excellent repeatability, long-time stability, temperature stability, and selectivity.
A microwave microfluidic non-enzymatic glucose sensor is proposed for measuring the concentration of glucose in aqueous solution, which is realized by combining a single-port dumbbell defective ...ground structure (DB-DGS) resonator with a microfluidic channel at the center bar area of the dumbbell. The microfluidic channel, which is made of PDMS, is used to deliver the glucose solution to the dumbbell bar sensitive area of the sensor. The glucose concentration can be measured by recording the change in amplitude of the return loss S11 at the resonance frequency. The DB-DGS sensor possesses high sensitivity owing to the high-intensity electric field generated at the dumbbell bar area when it reaches resonance. The sensor demonstrated fast response time of 16.2 s, good accuracy (the measured glucose values deviate from the actual glucose values by less than 20%), long-term stability (the relative standard deviation for 30-days is 3%), repeatability (the relative standard deviation for different sensors is 2.3%).
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