Fast-response oxygen sensitive transparent coating for inner pressure ratiometric optical mapping

In this work, dual-luminophore self-referenced pressure sensitive paint (PSP) was prepared with siloxane precursors by using copolymerizable silane-functionalized carbon dots (SiCDs) as a reference probe and a newly synthesized silane-modified...

A blade tip-timing method without once-per-revolution sensor for blade vibration measurement in gas turbine engines

The blade vibration measurement is crucial for gas turbine engines in order to ensure safe operations. One of the techniques is blade tip-timing (BTT), which is under the assumption that rotor speed is constant and depends on a once-per-revolution (OPR) timing reference to calculate the blade tip displacement, and identifying the blade sequence. However, this assumption is incorrect for transient conditions, and the installation of OPR sensor sometimes is not allowable and reliable. These reasons greatly limit the application of BTT technique. This paper proposes a self-correcting (SC) BTT method to realize the blade vibration measurement under different operating conditions without using the OPR sensor, which is based on the polynomial fitting and a reference probe is used to correct high-order fitting coefficients. Numerical results show that the SC-BTT method can greatly reduce the fitting error caused by blade pitch and vibrational parameters. Experimental results demonstrate that the proposed technique is capable of removing the limitation of the lack of OPR sensor and overcoming the drawbacks of OPR system, such as the failure of OPR sensor or low-speed resolution. For three investigated cases, the relative errors of derived rotor speed are below 0.12%. The relative error of blade peak-to-peak amplitude (PPA) and the initial phase angle are around 3% at the resonance region with engine order (EO) 2.

Asynchronous electric field visualization using an integrated multichannel electro-optic probe

The higher the frequency, the more complex the scattering, diffraction, multiple reflection, and interference that occur in practical applications such as radar-installed vehicles and transmitter-installed mobile modules, etc. Near-field measurement in “real situations” is important for not only investigating the origin of unpredictable field distortions but also maximizing the system performance by optimal placement of antennas, modules, etc. Here, as an alternative to the previous vector-network-analyzer-based measurement, we propose a new asynchronous approach that visualizes the amplitude and phase distributions of electric near-fields three-dimensionally without placing a reference probe at a fixed point or plugging a cable to the RF source to be measured. We demonstrate the visualization of a frequency-modulated continuous wave (FMCW) signal (24 GHz ± 40 MHz, modulation cycle: 2.5 ms), and show that the measured radiation patterns of a standard horn antenna agree well with the simulation results. We also demonstrate a proof-of-concept experiment that imitates a realistic situation of a bumper installed vehicle to show how the bumper alters the radiation patterns of the FMCW radar signal. The technique is based on photonics and enables measuring in the microwave to millimeter-wave range.

Technical and Anatomical Considerations for Reproducible Inactivation of Large Animal Carcasses by Steam Sterilization

Introduction: The complete inactivation of infectious tissues of large animal carcasses is one of the most challenging tasks in high-containment facilities. Steam sterilization is a method frequently in use to achieve biological inactivation of liquid and solid waste. Objective: This study aims to highlight parameters most effective in creating reproducible cycles for steam sterilization of pig and calf carcasses. Methods: Two pigs or 1 calf were sterilized by running a liquid cycle (n = 3) at 121°C for at least 120 minutes in a pass-through autoclave. To assess the physical and biological parameters, temperature data loggers and biological indicators (BIs) with spores of Geobacillus stearothermophilus (ATCC 7953) were placed at defined positions within animal carcasses. After completion of each cycle, data loggers were analyzed and BIs were incubated for 7 days at 60°C. Results: Initial testing with an undissected pig carcass resulted in suboptimal temperatures at the tissue level with growth on 1 BI. After modifications of the used stainless-steel boxes and by placing the reference probe of the autoclave in the animal carcass, reproducible cycles could be created. A complete inactivation of BIs and a temperature profile of >121°C for at least 20 minutes could be achieved in almost all probed tissues. Conclusion: Only minor modifications in carcass preparation and the used sterilization equipment resulted in effective and reproducible cycles to inactivate large animal carcasses by using a steam autoclave.

Ratiometric Strategy for Electrochemical Sensing of Carbaryl Residue in Water and Vegetable Samples

Accurate analysis of pesticide residue in real samples is essential for food safety and environmental protection. However, a traditional electrochemical sensor based on single-signal output is easily affected by background noise, environmental conditions, electrode diversity, and a complex matrix of samples, leading to extremely low accuracy. Hence, in this paper, a ratiometric strategy based on dual-signal output was adopted to build inner correction for sensing of widely-used carbaryl (CBL) for the first time. By comparison, Nile blue A (NB) was selected as reference probe, due to its well-defined peak, few effects on the target peak of CBL, and excellent stability. The effects of a derivatization method, technique mode, and pH were also investigated. Then the performance of the proposed ratiometric sensor was assessed in terms of three aspects including the elimination of system noise, electrode deviation and matrix effect. Compared with traditional single-signal sensor, the ratiometric sensor showed a much better linear correlation coefficient (r > 0.99), reproducibility (RSD < 10%), and limit of detection (LOD = 1.0 μM). The results indicated the introduction of proper reference probe could ensure the interdependence of target and reference signal on the same sensing environment, thus inner correction was fulfilled, which provided a promising tool for accurate analysis.

Dye-Doped ZnO Microcapsules for High Throughput and Sensitive Optofluidic Micro-Thermometry

The main objective of this work is to show the proof of concept of a new optofluidic method for high throughput fluorescence-based thermometry, which enables the measure of temperature inside optofluidic microsystems at the millisecond (ms) time scale (high throughput). We used droplet microfluidics to produce highly monodisperse microspheres from dispersed zinc oxide (ZnO) nanocrystals and doped them with rhodamine B (RhB) or/and rhodamine 6G (Rh6G). The fluorescence intensities of these two dyes are known to depend linearly on temperature but in two opposite manner. Their mixture enables for the construction of reference probe whose fluorescence does not depend practically on temperature. The use of zinc oxide microparticles as temperature probes in microfluidic channels has two main advantages: (i) avoid the diffusion and the adsorption of the dyes inside the walls of the microfluidic channels and (ii) enhance dissipation of the heat generated by the focused incident laser beam thanks to the high thermal conductivity of this material. Our results show that the fluorescence intensity of RhB decreases linearly with increasing temperature at a rate of about −2.2%/°C, in a very good agreement with the literature. In contrast, we observed for the first time a nonlinear change of the fluorescence intensity of Rh6G in ZnO microparticles with a minimum intensity at a temperature equal to 40 °C. This behaviour is reproducible and was observed only with ZnO microparticles doped with Rh6G.

Applicability of Transcutaneous Oxygen Tension Measurement in the Assessment of Chronic Limb-Threatening Ischemia

Transcutaneous oxygen tension measurement (TcPO2) is widely applied for the evaluation of chronic limb-threatening ischemia (CLTI). Nevertheless, studies that focused on the clinical value of TcPO2 have shown varying results. We identified factors that potentially play a role in TcPO2 measurement variation such as probe placement, probe temperature, and the use of a reference probe. In this review of the current literature, we assessed the application of these factors. A systematic search was conducted. Parameters that were assessed were probe placement, probe temperature, and mentioning and/or use of a reference probe. In total, 36 articles were eligible for analysis. In 24 (67%) studies, probes were placed on specific anatomical locations. Seven (19%) studies placed probes, regardless of the location of the ulcer, adjacent to an ischemic lesion or ulcer (perilesion). Selected temperature setting of the probe differed; in 18 (50%), a default probe temperature of 44°C was selected, and in 13 (36%), a different temperature was selected. In 31 (84%) studies, the use of a reference probe was not reported. Transcutaneous oxygen tension measurement is applied diversely in patients with CLTI. Homogeneity in TcPO2 protocols is warranted for reliable clinical application and to compare future TcPO2 research.