Metal-coated high-temperature strain optical fiber sensor based on cascaded air-bubble FPI-FBG structure.

Metal coatings can protect the fragile optical fiber sensors and extend their life in harsh environments. However, simultaneous high-temperature strain sensing in a metal-coated optical fiber remains relatively unexplored. In this study, a nickel-coated fiber Bragg grating (FBG) cascaded with an air bubble cavity Fabry-Perot interferometer (FPI) fiber optic sensor was developed for simultaneous high temperature and strain sensing. The sensor was successfully tested at 545 °C for 0-1000 µÉ›, and the characteristic matrix was used to decouple temperature and strain. The metal layer allows easy attachment to metal surfaces that operate at high temperatures, enabling sensor-object integration. As a result, the metal-coated cascaded optical fiber sensor has the potential to be used in real-world structural health monitoring.

Combined analysis of whole-exome sequencing and RNA sequencing in type 2 diabetes mellitus patients with thirst and fatigue.

BACKGROUND: The principal objective of this study was to gain a better understanding of the mechanisms of type 2 diabetes mellitus (T2DM) patients with fatigue (D-T2DM) through exome and transcriptome sequencing. METHODS: After whole-exome sequencing on peripheral blood of 6 D-T2DM patients, the consensus mutations were screen out and analyzed by a series of bioinformatics analyses. Then, we combined whole-exome sequencing and transcriptome sequencing results to find the important genes that changed at both the DNA and RNA levels. RESULTS: The results showed that a total of 265,393 mutation sites were found in D-T2DM patients compared with normal individuals, 235 of which were consensus mutations shared with D-T2DM patients. These genes significantly enriched in HIF-1 signaling pathway and sphingolipid signaling pathway. At the RNA level, a total of 375 genes were identified to be differentially expressed. After the DNA-RNA joint analysis, eight genes were screened that changed at both DNA and RNA levels. Among these genes, FUS and LMNA were related to carbohydrate metabolism, energy metabolism, and mitochondrial function. Subsequently, we predicted the herbs, including Qin Pi and Hei Zhi Ma, that might play a therapeutic role in D-T2DM through the SymMap database. CONCLUSION: These findings have significant implications for understanding the mechanisms of D-T2DM and provide potential targets for D-T2DM diagnosis and treatment.

MEA-Net: multilayer edge attention network for medical image segmentation.

Medical image segmentation is a fundamental step in medical analysis and diagnosis. In recent years, deep learning networks have been used for precise segmentation. Numerous improved encoder-decoder structures have been proposed for various segmentation tasks. However, high-level features have gained more research attention than the abundant low-level features in the early stages of segmentation. Consequently, the learning of edge feature maps has been limited, which can lead to ambiguous boundaries of the predicted results. Inspired by the encoder-decoder network and attention mechanism, this study investigates a novel multilayer edge attention network (MEA-Net) to fully utilize the edge information in the encoding stages. MEA-Net comprises three major components: a feature encoder module, a feature decoder module, and an edge module. An edge feature extraction module in the edge module is designed to produce edge feature maps by a sequence of convolution operations so as to integrate the inconsistent edge information from different encoding stages. A multilayer attention guidance module is designed to use each attention feature map to filter edge information and select important and useful features. Through experiments, MEA-Net is evaluated on four medical image datasets, including tongue images, retinal vessel images, lung images, and clinical images. The evaluation values of the Accuracy of four medical image datasets are 0.9957, 0.9736, 0.9942, and 0.9993, respectively. The values of the Dice coefficient are 0.9902, 0.8377, 0.9885, and 0.9704, respectively. Experimental results demonstrate that the network being studied outperforms current state-of-the-art methods in terms of the five commonly used evaluation metrics. The proposed MEA-Net can be used for the early diagnosis of relevant diseases. In addition, clinicians can obtain more accurate clinical information from segmented medical images.

Signal-enhanced and bi-directional interferometric Rayleigh scattering velocimetry using an asymmetry cavity.

Interferometric Rayleigh scattering technique is commonly employed to measure single-point velocity fluctuation and its standard deviation in a high-speed flow due to many benefits, such as high accuracy, easy data interpretation, and high sampling rate. However, this technique suffers from a severe problem often referred to as the weak Rayleigh scattering signal, especially in the supersonic and hypersonic flow with an extremely low gas molecule density. An asymmetry cavity structure that could cost-effectively improve the Rayleigh scattering (RS) signal of interest is designed and used in the interferemetric Rayleigh scattering technique. The ZEMAX simulations suggest that the parallel beam can be repeatedly reflected in the resonant cavity and can be focused in a measurement region with the order of 0.67 mm×1.31 mm. The number of propagating rays inside the cavity can reach about 50. The fidelity of this proposed cavity is then verified by the Rayleigh scattering imaging experiments. Results show that this cavity allows the laser beam to reflect several times in the resonant cavity, and the RS signal intensity in the major axis can be 10.4 times larger than that of the incident laser. The cavity is finally employed under realistic supersonic flow velocity measurements, where the results conclusively illustrate that the Rayleigh scattering signal of interest in a single direction can be improved by a factor of 4∼5. In addition, the bi-directional (both the axial and radial directions) velocity parameters can also be obtained simultaneously. The axial velocity and its standard deviation are similar to conventional single-line ones.

Transcriptome Sequencing Analysis of Peripheral Blood of Type 2 Diabetes Mellitus Patients With Thirst and Fatigue.

Purpose: The purpose of this study is to explore the differences in transcriptome expression profiles between healthy subjects and type 2 diabetes mellitus patients with thirst and fatigue (D-T2DM) and, in addition, to investigate the possible role of noncoding ribonucleic acids (RNAs) in the pathogenesis of D-T2DM. Methods: We constructed the expression profiles of RNAs by RNA sequencing in the peripheral blood of D-T2DM patients and healthy subjects and analyzed differentially expressed RNAs. Results: Compared with healthy subjects, a total of 469 mRNAs, 776 long non-coding RNAs (lncRNAs), and 21 circular RNAs (circRNAs) were differentially expressed in D-T2DM patients. Furthermore, several genes associated with insulin resistance, inflammation, and mitochondrial dysfunction were identified within the differentially expressed mRNAs. Differentially expressed lncRNAs were primarily involved in biological processes associated with immune responses. In addition, differentially expressed circRNAs may target miRNAs associated with glucose metabolism and mitochondrial function. Conclusions: Our results may bring a new perspective on differential RNA expression involved in the pathogenesis of D-T2DM and promote the development of novel treatments for this disease.

Combined analysis of whole-exon sequencing and lncRNA sequencing in type 2 diabetes mellitus patients with obesity.

This study sought to find more exon mutation sites and lncRNA candidates associated with type 2 diabetes mellitus (T2DM) patients with obesity (O-T2DM). We used O-T2DM patients and healthy individuals to detect mutations in their peripheral blood by whole-exon sequencing. And changes in lncRNA expression caused by mutation sites were studied at the RNA level. Then, we performed GO analysis and KEGG pathway analysis. We found a total of 277 377 mutation sites between O-T2DM and healthy individuals. Then, we performed a DNA-RNA joint analysis. Based on the screening of harmful sites, 30 mutant genes shared in O-T2DM patients were screened. At the RNA level, mutations of 106 differentially expressed genes were displayed. Finally, a consensus mutation site and differential expression consensus gene screening were performed. In the current study, the results revealed significant differences in exon sites in peripheral blood between O-T2DM and healthy individuals, which may play an important role in the pathogenesis of O-T2DM by affecting the expression of the corresponding lncRNA. This study provides clues to the molecular mechanisms of metabolic disorders in O-T2DM patients at the DNA and RNA levels, as well as biomarkers of the risk of these disorders.

Translational, rotational, vibrational and electron temperatures of a gliding arc discharge.

Translational, rotational, vibrational and electron temperatures of a gliding arc discharge in atmospheric pressure air were experimentally investigated using in situ, non-intrusive optical diagnostic techniques. The gliding arc discharge was driven by a 35 kHz alternating current (AC) power source and operated in a glow-type regime. The two-dimensional distribution of the translational temperature (Tt) of the gliding arc discharge was determined using planar laser-induced Rayleigh scattering. The rotational and vibrational temperatures were obtained by simulating the experimental spectra. The OH A-X (0, 0) band was used to simulate the rotational temperature (Tr) of the gliding arc discharge whereas the NO A-X (1, 0) and (0, 1) bands were used to determine its vibrational temperature (Tv). The instantaneous reduced electric field strength E/N was obtained by simultaneously measuring the instantaneous length of the plasma column, the discharge voltage and the translational temperature, from which the electron temperature (Te) of the gliding arc discharge was estimated. The uncertainties of the translational, rotational, vibrational and electron temperatures were analyzed. The relations of these four different temperatures (Te>Tv>Tr >Tt) suggest a high-degree non-equilibrium state of the gliding arc discharge.

Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering.

Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.

Stray light suppression in spectroscopy using periodic shadowing.

It is well known that spectroscopic measurements suffer from an interference known as stray light, causing spectral distortion that reduces measurement accuracy. In severe situations, stray light may even obscure the existence of spectral lines. Here a novel general method is presented, named Periodic Shadowing, that enables effective stray light elimination in spectroscopy and experimental results are provided to demonstrate its capabilities and versatility. Besides its efficiency, implementing it in a spectroscopic arrangement comes at virtually no added experimental complexity.

Power scaling analysis of tandem-pumped Yb-doped fiber lasers and amplifiers.

Taking the improved SRS threshold formula into consideration, the power scaling of tandem-pumped Yb-doped silica fiber lasers and amplifiers is analyzed by new models. The results show that the power scaling of tandem-pumped Yb-doped fiber lasers and amplifiers is primarily limited by optical damage, SRS and thermal lens, while the pump brightness induced limitation is almost removed. It is also found that tandem-pumped Yb-doped fiber lasers and amplifiers, based upon state-of-art fiber technology, have the potential to achieve a power limit of 70.7 kW with a core diameter of 63.4 µm, and in the case of a strict single-mode fiber, the power limit is about 13.3 kW with a core numerical aperture of 0.03.

Coherent beam combination of 1.08 kW fiber amplifier array using single frequency dithering technique.

Coherent beam combination of a 1.08 kW fiber amplifier array has been demonstrated for the first time, to our knowledge. In the experiment, nine fiber amplifiers are tiled into a 3×3 array, and the output power of each amplifier is approximately 120 W. A single frequency dithering algorithm is used to compensate the phase noises between the elements, which runs on a signal processor based on field programmable gate array for phase control on the fiber amplifiers. When the phase control system goes into closed loop, the fringe contrast of the far-field intensity pattern is improved to more than 85%, and the residual phase error is less than λ/15.