Frequency Fr Research Articles

Fungal Contaminant of Poultry Feed in Basrah, Iraq

A total of 180 samples of concentrated poultry feed were collected from different broilers, broiler breeders, layers farms and local market of poultry in Basrah province. Feed samples were collected during the period from Sep. 2014 to Apr. 2015. About 10 - 30 representative samples of 1 kg were collected from several locations. They were cultured on Potato dextrose agar (PDA) and malt extract agar (MEA) and then sub cultured on Sabouraud dextrose agar (SDA). Seven genera were recovered from 180 samples of poultry feed .The most genera which recovered were Aspergillus spp. frequency (Fr) 62.77% - Relative density (RD) 52.03%), followed by Penicillium spp. (Fr 47.77% - RD 17.01%) and they were the predominant genera isolated from poultry feed. Fusarium spp. isolates were less frequency and relative density (Fr.1.66%, RD 2.11%). The most frequently isolated Aspergillus spp. was Aspergillys flavus ( Fr 65.48%) and had the most RD (27.55%), followed by Aspergillus niger (Fr. 58.40%, RD14.23%), the less occurrence of Aspergillus spp. was Aspergillus paraciticus (Fr.1.76%, RD0.89%).

Cardio‐respiratory patterning varies during E. coli peritonitis in Sprague‐Dawley male rats

Sepsis is distinguished by an overwhelming uncontrolled inflammatory response to a pathogen (e.g. Escherichia coli, E. coli). The interval from the onset of sepsis to treatment is a critical factor for patient survival. We hypothesize that ventilatory pattern variability (VPV; autocorrelation coefficient (r), Mutual Information, (MI), Sample Entropy (SampEn) and nonlinear complexity index (NLCI)), respiratory frequency (fR), and cardio-ventilatory coupling (CVC) are biometrics that vary with neural inflammation and may signal the onset of a sepsis. Male, Sprague Dawley rats (n=35) received surgically implanted pressure transducers (DSI telemetry; arterial blood pressure, (BP)), allowed 2wks to recover, then placed unanesthetized in whole-body plethysmography (Buxco) set on a receiver (EMKA) for baseline (0h) recordings. Then, we implanted them with a thrombin-fibrinogen pellet, which was either sterile (D0) or contained 25 x 106 CFU E. coli (D25). After inoculation, we recorded ventilation at 3h (D0 n=5, D25 N=5), 6h (D0 n=3, D25 n=5), 15h (D0 n=4, D25 n=4), 24h (D0 n=4, D25 n=5) and analyzed fR, VPV & CRC. We tested for differences with a 2-way, repeated-measures ANOVA, both within groups between 0h and each hour and between D0 and D25 at each hour. fR did not differ from 0h or between D0 and D25 by 3, 6 and12h; but increased by 24h (D0 and D25 (p<001)). Similarly, VPV became more predictable by 15h D25 (r at 1 cycle length, D0 0.59 ± 0.08 vs 0.69 ± 0.201, p<0.001; MI, D0 0.37 ± 0.100 vs D25 0.49 ± 0.11 bits, p<.001; and NLCI, D0 0.08 ± 0.05 vs D25 0.15 ± 0.04 p<0.001). CVC changed, in the distribution (χ2) of the intervals between the peak of the R-wave the transition from expiration-to-inspiration phase switch (EIPS) by 15h for D25 (D0, 66.3 ± 53.1 vs D25, 31.2 ± 19.1, p< 0.001). Transformed relative Shannon entropy (tRSE) for the R-wave-to-EIPS intervals did not differ at any time point. Heart rate (HR) changed at 15hr for D25 (D0, 400 ± 47 vs D25, 445 ± 33, p<0.001). These results suggest that fR, VPV and CVC biometrics change as systemic infection progresses and may be useful measures of sepsis progression over time in critically ill patients.

Seismic site characterization and site response study of Nirsa (India)

The Nirsa block, a coal mining area, and an industrial town lies in the southern part of Dhanbad district, at the border between the Indian states of Jharkhand and West Bengal. This area manifests the significant seismic risk posed by earthquakes, natural as well as induced, of high enough seismic intensity VI and VII from regional and local earthquakes. Hence, it is indispensable to seismically characterize the top surficial layers to reduce the risk associated with earthquakes in this region. We characterize these layers, using ambient noise acquired from multichannel simulation with one receiver and single station method to subsequently invert for shear wave velocities, via iterative global search technique of the guided Monte Carlo method by fitting fundamental mode Rayleigh wave phase velocity dispersion curves and horizontal-to-vertical spectral ratios (HVSR). We survey the area to record a sufficient amount of ambient noise within the frequency range of 1–30 Hz at seventy-eight observation points, with uniform spacing of 250 m, covering a total area of about 4 km2. Our results reveal that the bedrock depth lies in the range of 19.5–2.7 m; while Vs30 values vary in the range of 250–950 m/s in the Nirsa region. The variations in fundamental resonance frequencies, obtained from HVSR curves, are found to be more scattered in the range between 2 and 23 Hz. The maps of fundamental resonance frequency, peak HVSRs’ amplitude, bedrock depth and Vs30 derived from this research exhibit good correlation with each other. The Vs30 prediction equation based on the fundamental resonance frequency (fr) and HVSR amplitude (A0) will help future studies to determine Vs30 of unknown regional sites. The efficacy of our results is reliable as there is good concurrence between shear wave velocity profiles, HVSR profiles and litholog data sets. Our results may prove to be important assets to agencies such as National Disaster Management Authorities and Geological Survey of India for construction of seismic microzonation maps in Nirsa.

Unraveling the Mechanisms Underlying Irregularities in Inspiratory Rhythm Generation in a Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder anatomically characterized by a progressive loss of dopaminergic neurons in the substantia nigra compacta (SNpc). Much less known, yet clinically very important, are the detrimental effects on breathing associated with this disease. Consistent with the human pathophysiology, the 6-hydroxydopamine hydrochloride (6-OHDA) rodent model of PD shows reduced respiratory frequency (fR) and NK1r-immunoreactivity in the pre-Bötzinger complex (preBötC) and PHOX2B+ neurons in the retrotrapezoid nucleus (RTN). To unravel mechanisms that underlie bradypnea in PD, we employed a transgenic approach to label or stimulate specific neuron populations in various respiratory-related brainstem regions. PD mice were characterized by a pronounced decreased number of putatively rhythmically active excitatory neurons in the preBötC and adjacent ventral respiratory column (VRC). Specifically, the number of Dbx1 and Vglut2 neurons was reduced by 47.6% and 17.3%, respectively. By contrast, inhibitory Vgat+ neurons in the VRC, as well as neurons in other respiratory-related brainstem regions, showed relatively minimal or no signs of neuronal loss. Consistent with these anatomic observations, optogenetic experiments identified deficits in respiratory function that were specific to manipulations of excitatory (Dbx1/Vglut2) neurons in the preBötC. We conclude that the decreased number of this critical population of respiratory neurons is an important contributor to the development of irregularities in inspiratory rhythm generation in this mouse model of PD.SIGNIFICANCE STATEMENT We found a decreased number of a specific population of medullary neurons which contributes to breathing abnormalities in a mouse model of Parkinson's disease (PD).

Structural, thermal, and ion dynamics studies of PVA-CS-NaI-based biopolymer electrolyte films

A series of biopolymer blend electrolytes (BPBEs) based on ((100-x)PVA-xCS)-NaI, viz. BPBE-1 to BPBE-5 (x = 10, 20, 30, 40, 50 in wt%), respectively, were prepared using solution cast technique. Prepared samples have been characterized using XRD, ATR-FTIR, TGA, and AC impedance spectroscopic techniques. ATR-FTIR results reveal the interactions between the constituents of PVA/CS with salt, NaI. XRD results show the semi-crystalline nature of PVA-CS polymer blend and %degree of crystallinity (Xc) was found to be minimum for sample BPBE-1. TGA and its 1st derivative (DTGA) results show that BPBE films decompose in multi-steps. The decomposition temperature peak (Td, peak) associated with CS-PVA polymer blend and the interactions between CS-PVA-NaI have been discussed using TGA analysis. Temperature-dependent dc conductivity (σdc) and relaxation frequency (fr) follow the Arrhenius type mechanism. The optimum σdc ~ 1.2 × 10−5 S/cm at 30 °C was received for sample, BPBE-1. The ac conductivity spectra for all samples follow the Jonscher’s power law (JPL). Dielectric permittivity and electric modulus studies have also been done for understanding the charge storage properties and conductivity relaxation. Ionic transference number (ITN) measurement has been carried out for knowing the ionic/electronic nature of charge species. Cyclic voltammetry (CV) measurement has been done to study the electrochemical behavior of the optimized sample.

Excitation-frequency determination based on electromechanical impedance spectroscopy for a laser-microfabricated cavitation microstreaming micromixer

We for the first time propose and validate an electromechanical impedance spectroscopy (EMIS) technique to determine the resonance frequency (fr) of micromixers for effective cavitation microstreaming. Theoretical fr predictions of the oscillating bubble have been inaccurate because it was assumed that the bubble had a spherical shape even though bubbles are commonly trapped in low-profile air pockets, and thus their shapes are not spherical. Empirical excitation-frequency search has been employed but it was time-consuming and could overlook the exact value of fr. Strong electromechanical coupling between a piezoelectric transducer and a microfluidic chip (i.e., a mechanical structure) allows straightforward, rapid fr determination (∼4.5 min) using EMIS. To validate the EMIS method, we compare microstreaming patterns generated by bubbles excited at four different resonance frequencies using a high-speed imaging setup: 1) fr,B, the theoretical fr assuming a spherical bubble, 2) fr,Beq, the theoretical fr based on the concept of an “equivalent spherical bubble” having a surface area equal to the vibrating air-water interface area, 3) fr,Pf, the EMIS-based fr of a piezoelectric transducer, and 4) fr,Cf, the EMIS-based fr of the microfluidic chip bonded with the transducer. After confirming that fr,Cf yields the strongest cavitation microstreaming, the air-pocket shape is designed with consideration of the bubble stability and mixing effectiveness. A micromixer chip with the designed air pockets is excited at fr,Cf and exhibits rapid homogenization (37.2 s) of diluted ink and deionized water in the mixing chamber of a substantial volume (61.9 μL). Additionally, an experimentally validated, adhesive-tape-supported laser microfabrication technique allows rapid prototyping (∼10 min) of polymethyl methacrylate microfluidic chips with an excellent dimensional accuracy, machining resolution, and surface smoothness. We expect the proposed EMIS-based technique for resonance-frequency determination and the simple, rapid laser microfabrication method to be widely employed for bio-/chemical microfluidic applications in the near future.

Ferromagnetic-waveguide width dependence of propagation properties for magnetostatic surface spin waves

The width dependence of propagation properties for magnetostatic surface spin waves (MSSWs) in Permalloy (Py) waveguides was investigated experimentally and numerically. When both the short-side width of a Py waveguide (WPy) and the magnetic field (μ0H) were large enough, the spin wave (SW) intensity almost linearly decreased with decreasing WPy, and the resonant frequency fr was almost independent of WPy. However, when both WPy and μ0H were small, the SW intensity rapidly reduced, and fr decreased with decreasing WPy. Micromagnetic simulations revealed that when both WPy and μ0H are large enough, the magnetization direction of Py is almost parallel to the magnetic field direction, and the SW mode becomes the MSSW mode. In contrast, when both WPy and μ0H are small, magnetization direction tilts to the long-side direction of the Py strip from the magnetic field direction due to a strong demagnetizing field, which is the origin of the unexpected reduction in the intensity and fr. When miniaturized ferromagnetic waveguides are used for shrinking MSSW devices, a sufficiently large magnetic field is necessary because the influence of the shape magnetic anisotropy cannot be ignored.

A heat and moisture-exchanging mask impairs self-paced maximal running performance in a sub-zero environment

PurposeHeat-and-moisture-exchanging devices (HME) are commonly used by endurance athletes during training in sub-zero environments, but their effects on performance are unknown. We investigated the influence of HME usage on running performance at − 15 °C.MethodsTwenty-three healthy adults (15 male, 8 female; age 18–53 years; dot{V}{text O}_{2peak} men 56 ± 7, women 50 ± 4 mL·kg−1·min−1) performed two treadmill exercise tests with and without a mask-style HME in a randomised, crossover design. Participants performed a 30-min submaximal warm-up (SUB), followed by a 4-min maximal, self-paced running time-trial (TT). Heart rate (HR), respiratory frequency (fR), and thoracic area skin temperature (Tsk) were monitored using a chest-strap device; muscle oxygenation (SmO2) and deoxyhaemoglobin concentration ([HHb]) were derived from near-infra-red-spectroscopy sensors on m. vastus lateralis; blood lactate was measured 2 min before and after the TT.ResultsHME usage reduced distance covered in the TT by 1.4%, despite similar perceived exertion, HR, fR, and lactate accumulation. The magnitude of the negative effect of the HME on performance was positively associated with body mass (r2 = 0.22). SmO2 and [HHb] were 3.1% lower and 0.35 arb. unit higher, respectively, during the TT with HME, and Tsk was 0.66 °C higher during the HME TT in men. HR (+ 2.7 beats·min−1) and Tsk (+ 0.34 °C) were higher during SUB with HME. In the male participants, SmO2 was 3.8% lower and [HHb] 0.42 arb. unit higher during SUB with HME.ConclusionOur findings suggest that HME usage impairs maximal running performance and increases the physiological demands of submaximal exercise.

Wireless Microfluidic Sensor for Metal Ion Detection in Water

In the present work, a wireless microfluidic sensor based on low-temperature cofired ceramic (LTCC) technology for real-time detection of metal ions in water is proposed. The wireless sensor is composed of a planar spiral inductor and parallel plate capacitor (LC) resonant antenna, which integrates with the microchannel in the LTCC substrate between the capacitor plates. Aqueous solutions of Pb(NO3)2, Cd(NO3)2, Mg(NO3)2, Ca(NO3)2, NaNO3, and KNO3 with concentrations of 0–100 mM were tested with the sensors. The metal ion and its concentration in water can be tested by the amplitude of the reflection coefficient (S11) and the resonance frequency (fr) of the wireless microfluidic sensor. The metal ion species can be distinguished from the wireless response behavior of the sensor. The detection limit of the sensor for the selected metal ionic solutions could reach as low as 5 μM. The normalized sensitivity of the sensor is 0.47%, which is higher than that of the reported liquid microfluidic sensors based on microwave resonators. The wireless microfluidic sensor of this study is promising for rapid and convenient detection of heavy metal ion pollutants in the industrial wastewater.

Mice and Rats Display Different Ventilatory, Hematological, and Metabolic Features of Acclimatization to Hypoxia.

Phylogeographic studies showed that house mice (Mus musculus) originated in the Himalayan region, while common rats (Rattus rattus and Rattus norvegicus) come from the lowlands of China and India. Accordingly, it has been proposed that its origins gave mice, but not rats, the ability to invade ecological niches at high altitudes (pre-adaptation). This proposal is strongly supported by the fact that house mice are distributed throughout the world, while common rats are practically absent above 2,500 m. Considering that the ability of mammals to colonize high-altitude environments (>2,500 m) is limited by their capability to tolerate reduced oxygen availability, in this work, we hypothesize that divergences in the ventilatory, hematological, and metabolic phenotypes of mice and rats establish during the process of acclimatization to hypoxia (Hx). To test this hypothesis male FVB mice and Sprague-Dawley (SD) rats were exposed to Hx (12% O2) for 0 h (normoxic controls), 6 h, 1, 7, and 21 days. We assessed changes in ventilatory [minute ventilation (VE), respiratory frequency (fR), and tidal volume (VT)], hematological (hematocrit and hemoglobin concentration), and metabolic [whole-body O2 consumption (VO2) and CO2 production (VCO2), and liver mitochondrial oxygen consumption rate (OCR) parameters]. Compared to rats, results in mice show increased ventilatory, metabolic, and mitochondrial response. In contrast, rats showed quicker and higher hematological response than mice and only minor ventilatory and metabolic adjustments. Our findings may explain, at least in part, why mice, but not rats, were able to colonize high-altitude habitats.

Last Word on Viewpoint: Nondyspnogenic acute hypoxemic respiratory failure in COVID-19 pneumonia-Breathing pattern in patients with SARS-CoV-2.

Last Word on Viewpoint: Nondyspnogenic acute hypoxemic respiratory failure in COVID-19 pneumonia-Breathing pattern in patients with SARS-CoV-2.

Compact Dual-Band Circularly Polarized Inverted y-Shaped Printed Monopole Antenna with Edge Ground

A compact dual-band circularly polarized (CP) printed antenna with microstrip line feed is studied in this paper. It consists of an inverted y-shaped radiator with an edge ground plane on the opposite side of the substrate. The edge ground plane plays important role in impedance bandwidth (IBW) enhancement. In order to enhance the axial ratio bandwidth (ARBW) by a significant amount, the dimensions of the inverted y-shaped radiator are optimized. The value of measured IBW is equal to 4.48 GHz (4.94–9.42 GHz; 62.39%) with the resonant frequency fr = 7.18 GHz. The proposed design exhibits the simulated IBW of 5.557 GHz (4.933–10.490 GHz; 72.05%) with the resonant frequency fr = 7.7 GHz. The corresponding simulated ARBWs are equal to 742.5 MHz (fCP1 = 6.32 GHz, 11.75%) and 1091.8 MHz (fCP2 = 8.32 GHz, 13.12%) within the range of simulated and measured IBW, respectively. The presented antenna is compact with the optimized dimension of 20×20×1.6 mm3, i.e. 0.54×0.54×0.044λgL3, where λgL is the guided wavelength at the simulated lower resonant frequency fgL = 4.933 GHz with size reduction of 39.7%. It is fabricated on the low cost FR-4 substrate with copper cladding. Measurement results validate simulated data from Ansys Electronics Desktop 2020 R1. The maximum simulated peak gain is equal to 4.796 dBi at 8.64 GHz within the CP band. The proposed antenna can be suitable for some portions of C- and X-, and ITU-8 GHz band wireless communication applications.

THE ANALYSIS OF THE THREE-PHASE INDUCTION MOTOR WITH DEEP ROTOR BARS THROUGH NUMERICAL SIMULATIONS UTILIZING A MODIFIED MATHEMATICAL MODEL

The three-phase induction machine mathematical model presented in the paper, is adequate for applying to the deep rotor bars case. The rotor resistance R’r(r), respectively its leakage inductivity L’r(r), depend upon the rotor currents’ frequency fr because of the skin effect. Following the previous considerations, one developed slip dependent analytical expressions of the rotor circuit resistance R’r(s), respectively rotor circuit leakage reactance L’r (s). A modified space phasor based mathematical model of the deep bar induction motor is tested through simulations to assess the motor’s characteristics. The results are in accordance with the literature.

Understanding ventilation and oxygen uptake of Pacific hagfish (Eptatretus stoutii), with particular emphasis on responses to ammonia and interactions with other respiratory gases.

The hagfishes are an ancient and evolutionarily important group, with breathing mechanisms and gills very different from those of other fishes. Hagfish inhale through a single nostril via a velum pump, and exhale through multiple separate gill pouches. We assessed respiratory performance in E. stoutii (31 ppt, 12ºC, 50-120g) by measuring total ventilatory flow ([Formula: see text]) at the nostril, velar (respiratory) frequency (fr), and inspired (PIO2) and expired (PEO2) oxygen tensions at all 12 gill pouch exits plus the pharyngo-cutaneous duct (PCD) on the left side, and calculated ventilatory stroke volume (S[Formula: see text]), % O2 utilization, and oxygen consumption (ṀO2). At rest under normoxia, spontaneous changes in [Formula: see text] ranged from apnea to > 400mlkg-1min-1, due to variations in both fr and S[Formula: see text]; "normal" [Formula: see text] averaged 137mlkg-1min-1, ṀO2 was 718µmolkg-1h-1, so the ventilatory convection requirement for O2 was about 11 L mmol-1. Relative to anterior gill pouches, lower PEO2 values (i.e. higher utilization) occurred in the more posterior pouches and PCD. Overall, O2 utilization was 34% and did not change during hyperventilation but increased to > 90% during hypoventilation. Environmental hypoxia (PIO2 ~ 8% air saturation, 1.67kPa, 13Torr) caused hyperventilation, but neither acute hyperoxia (PIO2 ~ 275% air saturation, 57.6kPa, 430Torr) nor hypercapnia (PICO2 ~ 1% CO2, 1.0kPa, 7.5Torr) significantly altered [Formula: see text]. ṀO2 decreased in hypoxia and increased in hyperoxia but did not change in hypercapnia. Acute exposure to high environmental ammonia (HEA, 10mM NH4HCO3) caused an acute decrease in [Formula: see text], in contrast to the hyperventilation of long-term HEA exposure described in a previous study. The hypoventilatory response to HEA still occurred during hypoxia and hyperoxia, but was blunted during hypercapnia. Under all treatments, ṀO2 increased with increases in [Formula: see text]. Overall, there were lower convection requirements for O2 during hyperoxia, higher requirements during hypoxia and hypercapnia, but unchanged requirements during HEA. We conclude that this "primitive" fish operates a flexible respiratory system with considerable reserve capacity.

Changes in the autonomic and respiratory patterns in mice submitted to short-term sustained hypoxia.

What is the central question of this study? Do mice submitted to sustained hypoxia present autonomic and respiratory changes similarly to rats? What is the main finding and its importance? Arterial pressure in the normal range, reduced baseline heart rate and tachypnoea were observed in behaving sustained hypoxia mice. Recordings in the in situ preparation of mice submitted to sustained hypoxia show an increase in cervical vagus nerve activity and a simultaneous reduction in thoracic sympathetic nerve activity correlated with changes in the respiratory cycle. Therefore, mice are an important model for studies on the modulation of sympathetic activity to the cardiovascular system and the vagus innervation of the upper airways due to changes in the respiratory network induced by sustained hypoxia. Short-term sustained hypoxia (SH) in rats induces sympathetic overactivity and hypertension due to changes in sympathetic-respiratory coupling. However, there are no consistent data about the effect of SH on mice due to the different protocols of hypoxia and difficulties associated with the handling of these rodents under different experimental conditions. In situ recordings of autonomic and respiratory nerves in SH mice have not been performed yet. Herein, we evaluated the effects of SH ( =0.1 for 24h) on baseline mean arterial pressure (MAP), heart rate (HR), respiratory frequency (fR ) and responses to chemoreflex activation in behaving SH mice. A characterization of changes in cervical vagus (cVN), thoracic sympathetic (tSN), phrenic (PN) and abdominal (AbN) nerves in SH mice using the in situ working heart-brainstem preparation was also performed. SH mice presented normal MAP, significant reduction in baseline HR, increase in baseline fR , as well as increase in the magnitude of bradycardic response to chemoreflex activation. In in situ preparations, SH mice presented a reduction in PN discharge frequency, and increases in the time of expiration and incidence of late-expiratory bursts in AbN activity. Nerve recordings also indicated a significant increase in cVN activity and a significant reduction in tSN activity during expiration in SH mice. These findings make SH mice an important experimental model for better understanding how changes in the respiratory network may impact on the modulation of vagal control to the upper airways, as well as in the sympathetic activity to the cardiovascular system.

Synthesis, crystal structure, high-resolution l13Cd and 13C MAS NMR investigation and dielectric study of [C2H10N2]Cd (SCN)4

A new crystalline polymer compound [C2H10N2]Cd (SCN)4 was synthesized and analyzed using XRD single crystal, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), complex impedance and solid state 13C and 113Cd CP/MAS NMR. The crystal structure shows that the cadmium atoms have a S4N2-hexa-coordination sphere, exhibiting pseudo-octahedral geometry. The Cd(II) atoms are bridged by two SCN− anions generating 1D polymeric chains. Crystal packing with significantly different interactions was determined by Hirshfeld surface analysis and discussed herein. The crystal packing was assured by mean of hydrogen bonds, Van der Waals and π-π interactions. Solid state 113Cd CP/MAS NMR shows that each distinct cadmium site in the cadmium thiocyanates exhibits multiplets that result from 113Cd,14N spin-spin coupling. Examination of the 13C CP/MAS NMR line shapes allows direct measurement of the indirect spin-spin coupling constants 1J(14N, 13C) = 28 Hz and 2J(111/113Cd,13C) = (75+8)Hz, for the unique N-bonded thiocyanate ligand. DSC analysis shows a phase transition at about 359 K. The temperature dependence of bulk conductivity σ(Rp) and relaxation frequency (fr) were described and discussed by the use of the Arrhenius relationship. The frequency dependence of the real part of the AC conductivity in both phases follows the Jonscher's universal dynamic law. The evolution of S(T) as function of temperatures suggests that the quantum mechanical tunneling QMT mechanism prevails in phases I and II.

Noncontact planar microwave sensor for liquid interface detection by a pixelated CSRR ‐loaded microstrip line

A pixelated complementary split-ring resonator (PCSRR)-loaded microstrip line is proposed for the detection of different liquid interfaces and its potential applications are described. The proposed sensor operation is based on the magnitude measurement, the transmission coefficient (S21) and resonance frequency (Fr) that depend on the electrical properties of the liquid. The PCSRR was designed to allow electromagnetic waves to interact with different layers of liquid inside a container. The sensor device and experiment system were fabricated and evaluated and water-vegetable oil-alcohol interfaces were measured. The sensors were capable of detecting noncontact liquid interfaces and have potential applications in the chemical, oil, and medical industries.

Coplanar electrode directly modulated lasers with different cavity length

AbstractA ridge‐waveguide (RW) directly modulated laser (DML) with a coplanar electrode structure is proposed and measured in this paper. Since utilizing the coplanar electrode can significantly reduce parasitic capacitance, the frequency responses of DMLs exhibit a quite low roll‐off. Shortening the cavity length L is attractive to enhance the high‐speed performance of DMLs, but it will increase the mirror loss and the chip resistance at the same time. We analyzed the static and dynamic characteristics of 200‐μm, 250‐μm, and 300‐μm lasers experimentally and theoretically to investigate the impact of L on the coplanar‐electrode DML. Shortening the cavity length can improve the relaxation oscillation frequency fr effectively. The 200‐μm DML achieves a bandwidth of 15.3 GHz. The fr is the most important limiting factor for the laser to obtain a wide bandwidth. Decreasing L and increasing the differential gain are promising for the further improvement of fr. However, shortening L causes a more severe thermal effect and the deterioration of the linearity. This trade‐off must be considered in the future study.

On the threshold of 1/2 order subharmonic emissions in the oscillations of ultrasonically excited bubbles

The pressure threshold for 1/2 order subharmonic (SH) emissions and period doubling during the oscillations of ultrasonically excited bubbles is thought to be minimum when the bubble is sonicated with twice its resonance frequency (fr). This estimate is based on studies that simplified or neglected the effects of thermal damping. In this work, the nonlinear dynamics of ultrasonically excited bubbles is investigated accounting for the thermal dissipation. Results are visualized using bifurcation diagrams as a function of pressure. Here we show that, and depending on the gas, the pressure threshold for 1/2 order SHs can be minimum at a frequency between 0.5fr≤f≤0.6fr. In this frequency range, the generation of 1/2 order SHs are due to the occurrence of 5/2 order ultra-harmonic resonance. The stability of such oscillations is size dependent. For an air bubble immersed in water, only bubbles bigger than 1 μm in diameter are able to emit non-destructive SHs in these frequency ranges.

Orientation control of optical mode ferromagnetic resonance: From uniaxial to omni-directional

Both high ferromagnetic resonance frequency (fr) and homogeneous angular performance are important for soft magnetic films to be used in high-frequency integrated circuit devices. However, high fr are obtainable only along the easy axis direction of the magnetic anisotropic materials. In uniaxially anisotropic FeCoB/Ru/FeCoB films, we could obtain an ultrahigh optical mode ferromagnetic resonance frequency (frO) up to 19.16 GHz along the easy axis under a self-bias field due to the enhancement from strong interlayer exchange coupling. However, the uniaxial intensity distribution of optical mode resonance seriously hinders the practical application in microwave components. In order to obtain the desired homogeneous angular performance, soft magnetic films with widely distributed magnetic anisotropy directions in the films were prepared and a nearly omni-directional frO with uniform values around 13.5 GHz was achieved. This study demonstrates that controlling the magnetic anisotropy's angular distribution is an effective way to obtain isotropic, self-bias magnetic films with ultrahigh fr.