Sensor application-related defect chemistry and electromechanical properties of langasite

The operation of langasite (La₃Ga₅SiO₁₄) resonators as sensors at elevated temperature and controlled atmospheres is examined. This paper focuses on mapping the regimes of gas-insensitive operation of uncoated langasite resonators and the correlation to langasite's defect chemistry for temperatures up to 1000 °C. As a measure of sensitivity, the fundamental resonant mode at 5 MHz is estimated to be determined to within ± 4 Hz by network analysis for resonators operated in air at temperatures below 1000 °C. The calculated frequency shift induced by redox-related reactions in langasite only exceeds the limit of ± 4 Hz below p_O2 ≈ 10^− 17 bar at 1000 °C, below 10^− 24 bar at 800 °C and below 10^− 36 bar at 600 °C. Water vapor is found to shift the resonance frequency at higher oxygen partial pressures. In the hydrogen-containing atmospheres applied here, langasite can be regarded as a stable resonator material above oxygen partial pressures of about 10^− 13 and 10^− 20 bar at 800 and 600 °C, respectively.     

Bio-inspired digital nanoactuators for photon and biomaterial manipulation

This paper presents a bio-inspired digital nanoactuation device (DND) for applications to nano-precision digital manipulation of photons and biomolecules. The structures and principles of DND device have been inspired from those of the biological muscle actuator. The bio-inspired DND, composed of a digital actuator and a nonlinear mechanical modulator, purifies the stroke of the digital actuator in order to generate the high-precision motion required for nano-positioning of photonic or bio-molecule devices. We design and fabricate two kind of DNDs: one with a linear modulator (l-DND) and the other with nonlinear modulator (n-DND), both having an identical input and output strokes of 15.2 μm and 5.4 μm, respectively. In experimental study, n-DND shows the repeatability of 12.3 ± 2.9 nm, superior to that of 27.8 ± 2.9 nm achieved by l-DND. We experimentally verify that the displacement purifying capability of the bio-inspired n-DND achieves nano-precision motion repeatability, applicable to photon and bio-molecule manipulation.     

High efficiency on-chip charge pump DC–DC converter for LCD drivers

An on-chip charge pump (CP) DC–DC converter applicable to potable displays is described. A merged 2×/3× booster eligible for both single-phase pumping and dual-phase pumping is developed. A closed-loop sensing scheme with analog/digital mixed-mode voltage regulation helps to ensure a low ripple output voltage and high power transfer efficiency. A test vehicle was implemented for a DC input range of 2.2–3.6 V and the DC output of 5 V with a load condition of 20 mA in a standard 0.35-μm 2poly-4metal CMOS process. The test results reveal output ripple of less than 80 mV and efficiency of 77.4% in the 2× dual phase mode.     

Temperature effects on the ultrasonic separation of fat from natural whole milk

This study showed that temperature influences the rate of separation of fat from natural whole milk during application of ultrasonic standing waves. In this study, natural whole milk was sonicated at 600 kHz (583 W/L) or 1 MHz (311 W/L) with a starting bulk temperature of 5, 25, or 40 °C. Comparisons on separation efficiency were performed with and without sonication. Sonication using 1 MHz for 5 min at 25 °C was shown to be more effective for fat separation than the other conditions tested with and without ultrasound, resulting in a relative change from 3.5 ± 0.06% (w/v) fat initially, of −52.3 ± 2.3% (reduction to 1.6 ± 0.07% (w/v) fat) in the skimmed milk layer and 184.8 ± 33.2% (increase to 9.9 ± 1.0% (w/v) fat) in the top layer, at an average skimming rate of ∼5 g fat/min. A shift in the volume weighted mean diameter (D[4,3]) of the milk samples obtained from the top and bottom of between 8% and 10% relative to an initial sample D[4,3] value of 4.5 ± 0.06 μm was also achieved under these conditions. In general, faster fat separation was seen in natural milk when natural creaming occurred at room temperature and this separation trend was enhanced after the application of high frequency ultrasound.     

A low noise 2 × 16 Ge:Sb focal-plane array: Paving the way for large format FPAs for far IR astronomy

Future astronomical instruments call for large format and high sensitivity far infrared focal-plane arrays to meet their science objectives. Arrays as large as 128 × 128 with sensitivities equal to or better than 10⁻¹⁸ W/√Hz are set as targets for the far IR instruments to be developed within the next 10 years. These seemingly modest goals present a not-so-modest quantum leap for far IR detector technology whose progress is hampered by a number of complexities; chief among them the development of low noise readouts operating at deep cryogenic temperatures and a viable hybridization scheme suitable for far IR detectors. In an effort to incrementally develop large-format photoconductor arrays, we have fabricated a 2 × 16 Ge:Sb array using the SBRC190 readout – a cryogenic 1 × 32 CTIA readout multiplexer initially developed for SOFIA’s AIRES instrument. In this paper we report the results of the extensive parametric tests performed on this array showing an impressive noise performance of 2.2 × 10⁻¹⁸ W/√Hz and a DQE of 0.41 despite some design limitations. With such an encouraging performance, this prototype array will serve as a platform for our future developmental effort.     

Electrical and dielectric properties of β-BaB2O4 (BBO) and CsLiB6O10 (CLBO) crystals

In barium borate (BBO) crystals, sodium and potassium ions, inherited due to the preparation technique, are dominant charge carriers. The conductivity between layers is higher; the conductivity activation energy and the conductivity at 350 °C being equal to 1.01±0.05 eV and (1.3±0.2)×10⁻⁸ S/cm, respectively. The conductivity activation energy and the conductivity at 350 °C along the channels are equal to 1.13±0.05 eV and to (4±0.2)×10⁻⁹ S/cm, respectively. Relative static permittivity is almost isotropic, and equal to 7.65±0.05. Upon storing of cesium–lithium borate (CLBO) crystals, pre-heating to 600 °C eliminates the influence of surface humidity. At 500 K, the ionic conductivity ranges from 4×10⁻¹² to 2×10⁻¹⁰ S/cm; the conductivity activation energy ranges from 1.01 to 1.17 eV. Relative static permittivity is equal to 7.4±0.3.     

An STM study of desorption-induced thallium structures on the Si(111) surface

The scanning tunneling microscopy is used to study morphology of a Tl adlayer in various stages of Tl desorption from the Si(111) surface. Transition from the Si(111)/(1 × 1)-Tl structure through the (√3 × √3)R30° mosaic phase to domains of metastable Si reconstructions is observed. Silicon substitutional atoms are found to be intrinsic to the (√3 × √3)R30° structure. The temperature dependence of the amount of residual Tl atoms on the surface is successfully fitted by a model using the first order desorption. The same desorption energy of (2.1 ± 0.3) eV and frequency prefactor 5 × 10^14 ± 2 s^? 1 during all stages of the desorption are sufficient for the fitting. It is concluded that bonding of Tl in both (1 × 1) and (√3 × √3) configurations is of the same nature.     

Resonance asymmetry phenomenon in waveguide-type optical ring resonator gyro

The intensity output of a silica waveguide ring resonator (WRR) was found to show an asymmetric resonance characteristic. To further analyze and better design the resonator micro optic gyro (RMOG) with a waveguide-type ring resonator, in-depth research of the characteristics of the resonance asymmetry is fully developed for the first time, to the best of our knowledge. Four possible sources of the resonance asymmetry are analyzed and their respective contributions are compared. These four error sources are differential normal mode losses in the coupler, the backscattering induced noises, the polarization fluctuations and the optical Kerr effect. The differential normal mode loss is suspected to be the major contributor to the observed resonance asymmetry in the fabricated silica WRR. Asymmetric resonance curve produces a large output bias error in the RMOG based on the phase modulation technique, which is related to the modulation frequency differences between the CW and CCW lightwaves. Theoretical analysis shows that replacing the reflector WRR with a transmitter one is helpful to eliminate the effect of the different normal mode losses in the coupler on the resonance asymmetry.     

Laser diode end-pumped passively Q-switched Tm,Ho:YLF laser with Cr:ZnS as a saturable absorber

Output performance of a continuous-wave (CW) laser diode end-pumped passively Q-switched Tm,Ho:YLF laser is demonstrated with a Cr:ZnS crystal as the saturable absorber. We particularly investigate the influence of saturable absorber's position in the resonator when the Cr:ZnS crystal is placed close to and far from the laser beam waist. We compare the experimental results at the two different positions, and find that the laser shows unusual output characteristics when the Cr:ZnS saturable absorber is placed close to the beam waist. The pulse width and the pulse energy almost keep constant, measured about 1.25 μs and 4 μJ respectively, when the pump power is changed in the range of 1–1.9 W. Moreover, the pulse repetition frequency can be tuned between 1.3 kHz and 2.6 kHz by changing the pump power. The output wavelength of the passively Q-switched laser shifts to 2053 nm from 2067 nm in CW operation.     

Quantitative local structure determination of R,R-tartaric acid on Cu(110): Monotartrate and bitartrate phases

The local adsorption site of the monotartrate and bitartrate species of R,R-tartaric acid deposited on Cu(110) have been determined by scanned-energy mode photoelectron diffraction (PhD). In the monotartrate phase the molecule is found to adsorb upright through the O atoms of the single deprotonated carboxylic acid (carboxylate) group, which are located in different off-atop sites with associated Cu―O bond lengths of 1.92 ± 0.08 Å and 1.93 ± 0.06 Å; the plane of the carboxylate group is tilted by 17 ± 6° off the surface normal. The bitartrate species adopts a ‘lying down’ orientation, bonding to the surface through all four O atoms of the two carboxylate groups, also in off-atop sites. Three slightly different models give comparably good fits to the PhD data, but only one of these is similar to that predicted by earlier density functional theory calculations. This model is found to have Cu―O bond lengths of 1.93 ± 0.08 Å and 1.95 ± 0.08 Å, while the planes of the carboxylate groups are tilted by 38 ± 6° from the surface normal.     

Structure relates to elastic recoil and functional role in quadriceps tendon and patellar ligament

Tendons and ligaments have similar but slightly different structure and composition. Crimps of tendons and ligaments are morphological structures related to the elastic functional properties of these connective tissues. Aim of this study was to investigate the morphological arrangement of collagen fibres, fibrils and crimping pattern of suprapatellar (rectus femoris tendon-RFT and vastus intermedius tendon-VIT) and infrapatellar connective tissues (patellar ligament-PL) to relate their structural aspects to their common function role of leg extension. RFT, VIT and PL were removed from knees of Sprague–Dawley rats and light and electron microscopy (TEM and SEM) performed. Sagittal sections showed that collagen array and crimping pattern were similar in RFT and PL but differed from VIT. Morphometric analysis confirmed that crimp number was about the same in RFT and PL (5.4 ± 1.4 and 6.1 ± 2.8 respectively), but it was almost three times higher in VIT (14.5 ± 4.7). Similarly crimp top angle in RFT and PL (141.5 ± 15.0° and 146.2 ± 12.2° respectively) was significantly higher than in VIT (122.3 ± 14.8°) and the crimp base length was more than twice as wide in RFT (75.5 ± 22.6 μm) and PL (72.3 ± 28.9 μm) than in VIT (36 ± 14.1 μm). The smaller, fewer and most crimped crimps in VIT show that this tendon has a greater elastic recoil and responds to higher forces as among quadriceps muscles the vastus intermedius belly contributes the most during knee extension. By contrast, RFT acting as a “stopper” tendon also plays a ligament role by limiting an excessive flexion of the joint during postural rest position of the knee.     

Fabry–Pérot cavities based on chemical etching for high temperature and strain measurement

In this paper, two hybrid multimode/single mode fiber Fabry–Pérot (FP) cavities were compared. The cavities fabricated by chemical etching are presented as high temperature and strain sensors. In order to produce this FP cavity a single mode fiber was spliced to a graded index multimode fiber with 62.5 μm core diameter. The Fabry–Pérot cavities were tested as a high temperature sensor in the range between room temperature and 700 °C and as strain sensors. A reversible shift of the interferometric peaks with temperature allowed to estimate a sensitivity of 0.75 ± 0.03 pm/°C and 0.98 ± 0.04 pm/°C for the sensor A and B respectively. For strain measurement sensor A demonstrated a sensitivity of 1.85 ± 0.07 pm/μ? and sensor B showed a sensitivity of 3.14 ± 0.05 pm/μ?. The sensors demonstrated the feasibility of low cost fiber optic sensors for high temperature and strain.     

Wettability,optical property of a superhydrophobic YAG film

A flame-like superhydrophobic yttrium aluminum garnet surface was obtained by a simple approach under ambient conditions. The influences of the concentration of curing agent and paraffin wax in course of the experiment were investigated. The as-prepared film shows superhydrophobicity which has a water contact angle of 158 ± 1.0°, and sliding angle of 4 ± 1.0°. Moreover, the water contact angle of the rough surface remained higher than 150°, after exposure for 10 days. Transmission electronic microscope, scanning electronic microscope, fluorescence spectrometer and atomic force microscope were also used to characterize the samples.     

Thermographic diagnosis system and imaging algorithm by distributed thermal data using single infrared sensor

An infrared diagnosis device provides two-dimensional images and patient-oriented results that can be easily understood by the inspection target by using infrared cameras. However, this device has disadvantages such as large size, high price, and inconvenient maintenance. In this regard, this study has proposed a small diagnosis device for body heat using a single infrared sensor and implementing an infrared detection system using a single infrared sensor and an algorithm that represents thermography using the obtained data on the temperature of the point source. The developed system had a temperature resolution of 0.1 °C and reproducibility of ±0.1 °C. The accuracy was 90.39% at the error bound of ±0 °C and 99.98% at that of ±0.1 °C. To evaluate the proposed algorithm and system, the infrared images of the camera method were compared. To verify the device’s clinical applicability, thermal images with clinical meaning were obtained from a patient who had lesions.     

A large-size SiO2 waveguide resonator used in integration optical gyroscope

We report on the resonance characteristics of a Si-based ring resonator model with the theory of multiple-beam interference. The resonator consists of a track pattern ring channel waveguides with radius of 2 cm, two input/output directional couplers and one ring resonator coupler. Using the wide angle finite-difference beam propagation method (WA-FDBPM), we presented optimal design of ring resonator and succeed in fabricating the ring resonator by Plasma Enhanced Chemical Vapor Deposition (PECVD) method. Observed from the resonance curve, finesse of 16.7 is measured. And a rate detection limit of 1.7°/h can be evaluated.     

The production of Sr hexaferrite thick films by screen printing

Hydrothermally synthesised Sr hexaferrite (HT-SrM) powder with a distinct plate-like shape and conventional Sr hexaferrite (c-SrM) powder were used to screen print SrM thick films on alumina substrates. In the case of the HT-SrM thick films, a very strong perpendicular magnetic anisotropy has been observed with remanence values of up to 42±2 J/T kg for the perpendicular direction and 15±1 J/T kg for the in-plane direction, and with coercivities of around 159±8 kA/m for both directions when fired at 1300°C. When fired at 1150°C, the remanences were 49±2 and 27±2 J/T kg for the two directions with a higher coercivity of 247±8 kA/m for both directions. The SEM micrographs showed that the platelet grains in the printed films lay with their flat surfaces on the substrate and XRD results revealed that the c-axis of the grains oriented perpendicularly to the film surface. The (0 0 8) plane, which is, for a random oriented sample, a very weak peak, appeared as the strongest in the XRD pattern for the films. EDX and XRD studies indicated significant reaction at the interfaces between the film and the substrate when the sintering temperature was raised to 1350°C.For the SrM thick films obtained from planetary milled ultrafine Sr hexaferrite and conventional Sr hexaferrite powder, a slight in-plane anisotropy could be observed with a coercivity of 318±8 kA/m.     

Polymorphic phase transition and thermal stability in squaric acid (H2C4O4)

Phase transformations in squaric acid (H₂C₄O₄) have been investigated by thermogravimetry and differential scanning calorimetry with different heating rates β. The mass loss in TG apparently begins at onset temperatures T_di=245±5 °C (β=5 °C min^?1), 262±5 °C (β=10 °C min^?1), and 275±5 °C (β=20 °C min^?1). A polymorphic phase transition was recognized as a weak endothermic peak in DSC around 101 °C (T_c⁺). Further heating with β=10 °C min^?1 in DSC revealed deviation of the baseline around 310 °C (T_i), and a large unusual exothermic peak around 355 °C (T_p), which are interpreted as an onset and a peak temperature of thermal decomposition, respectively. The activation energy of the thermal decomposition was obtained by employing relevant models. Thermal decomposition was recognized as a carbonization process, resulting in amorphous carbon.     

100-mW linear polarization single-frequency all-fiber seed laser for coherent Doppler lidar application

A compact short-cavity fiber laser configured with Er³⁺/Yb³⁺ highly co-doped phosphate glass fiber with stable linear polarization and single frequency output is proposed and investigated experimentally. The fiber laser is composed of a high-reflectivity fiber Bragg grating (HRFBG) and a polarization-maintaining fiber Bragg grating (PMFBG) with the matched wavelengths at 1540.3 nm, which aims at one of the center wavelengths of the atmospheric transmission windows and may be used as the local oscillator (LO) of the coherent Doppler lidar (CDL). The output power of the laser reaches more than 114-mW, the signal-to-noise ratio is larger than 70 dB and the laser linewidth is about 4.1-kHz. Moreover, the linear polarization with 40.5 dB extinction ratio, the power fluctuation of less than ± 0.25% and the frequency fluctuation of less than ± 80 MHz are also obtained. Compared with the DFB fiber laser, the proposed fiber laser is more suitable for the CDL applications.     

Three-dimensional black-blood T2 mapping with compressed sensing and data-driven parallel imaging in the carotid artery

PurposeTo develop a 3D black-blood T₂ mapping sequence with a combination of compressed sensing (CS) and parallel imaging (PI) for carotid wall imaging.Materials and methodsA 3D black-blood fast-spin-echo (FSE) sequence for T₂ mapping with CS and PI was developed and validated. Phantom experiments were performed to assess T₂ accuracy using a Eurospin Test Object, with different combination of CS and PI acceleration factors. A 2D multi-echo FSE sequence was used as a reference to evaluate the accuracy. The concordance correlation coefficient and Bland-Altman statistics were calculated. Twelve volunteers were scanned twice to determine the repeatability of the sequence and the intraclass correlation coefficient (ICC) was reported. Wall-lumen sharpness was calculated for different CS and PI combinations. Six patients with carotid stenosis > 50% were scanned with optimised sequence. The T₂ maps were compared with multi-contrast images.ResultsPhantom scans showed good correlation in T₂ measurement between current and reference sequence (r = 0.991). No significant difference was found between different combination of CS and PI accelerations (p = 0.999). Volunteer scans showed good repeatability of T₂ measurement (ICC: 0.93, 95% CI 0.84–0.97). The mean T₂ of the healthy wall was 48.0 ± 9.5 ms. Overall plaque T₂ values from patients were 54.9 ± 12.2 ms. Recent intraplaque haemorrhage and fibrous tissue have higher T₂ values than the mean plaque T₂ values (88.1 ± 6.8 ms and 62.7 ± 9.3 ms, respectively).ConclusionThis study demonstrates the feasibility of combining CS and PI for accelerating 3D T₂ mapping in the carotid artery, with accurate T₂ measurements and good repeatability.     

V-band directional tandem coupler of monolithic uniplanar structure

We present a uniplanar coplanar-waveguide 3-dB tandem coupler operating at V-band frequencies. The uniplanar structure is monolithically fabricated by using two-section parallel-coupled lines and air-bridge crossovers replacing the conventional multilayer or bonded structures. Due to an optimized tandem structure and non-bonded crossovers minimizing the parasitic components, a maximum coupling of 2.5 dB is measured at 62 GHz with a 2 dB bandwidth of 83%, while a high directivity factor of 33 dB is simultaneously obtained at 58–62 GHz. Over the entire design frequency range of 30–90 GHz, we achieve good phase unbalance of 90 ± 6.0°, as well as return loss and isolation lower than −23 and −16 dB, respectively.