Fiber-Optic Sensing for High-Temperature and Energy Applications

Fiber-optic sensors act as important roles in many of today's industrial sectors. It provides vital information for a large number of applications such as process controls, fossil fuel and nuclear electrical power generation, transportation, and environment monitoring. Compared with their electronic counterparts, fiber-optic sensors truly stand out where extreme operation environments leave almost all the electronic sensors unusable. Derived from the superior properties of optical fibers such as high-temperature stability, immunity to electromagnetic interference and strong resistance to most chemicals, fiber-optic sensors can be engineered to deliver sensing performance under various adverse conditions. Recently numerous research efforts have been put to leverage those merits of optical fibers to achieve sensing capabilities under high-temperature environments (> 600 deg C). In this thesis, five fiber-optic sensing schemes are demonstrated to explore and validate the potential of fiber-optic sensors for high-temperature and energy applications. The first scheme manifests itself as a high-temperature-stable distributed Bragg reflector (DBR) fiber laser which intrinsically is able to operate and measure ambient temperatures up to 750 deg C. The second scheme is based on self-heated high-attenuation fibers (HAFs). Thanks to HAFs and regenerated fiber Bragg gratings, a hot-wire flow meter with ambient temperature compensation was realized with all-optical fiber construction with maximum operational temperature at 800 deg C. In the third sensing scheme, the other kind of fiber grating laser, the distributed feedback (DFB) fiber laser as strain sensor is presented to monitor acoustic emissions for a lab-induced hydraulic fracturing process. The fourth scheme covers a 3D strain field imaging technique for hydraulic fracturing study, enabled by Rayleigh backscatter based optical frequency domain reflectometry (OFDR). In the fifth scheme, we are aiming at increasing the measurement accuracy of the OFDR system by reducing the system measurement noise level. Via cavity ring down method, the system noise is demonstrated to reduce by over 52%. All these technologies and devices offer reliable and flexible sensing solutions for high-temperature and energy industrials, which were not previously possible

Development of a compact vertical-cavity surface-emitting laser end-pumped actively Q-switched laser for laser-induced breakdown spectroscopy

This paper reports the development of a compact and portable actively Q-switched Nd:YAG laser and its applications in laser-induced breakdown spectroscopy (LIBS). The laser was end-pumped by a vertical-cavity surface-emitting laser (VCSEL). The cavity lases at a wavelength of 1064 nm and produced pulses of 16 ns with a maximum pulse energy of 12.9 mJ. The laser exhibits a reliable performance in terms of pulse-to-pulse stability and timing jitter. The LIBS experiments were carried out using this laser on NIST standard alloy samples. Shot-to-shot LIBS signal stability, crater profile, time evolution of emission spectra, plasma electron density and temperature, and limits of detection were studied and reported in this paper. The test results demonstrate that the VCSEL-pumped solid-state laser is an effective and compact laser tool for laser remote sensing applications

Fiber-optic flow sensors for high-temperature environment operation up to 800°C

This Letter presents an all-optical high-temperature flow sensor based on hot-wire anemometry. High-attenuation fibers (HAFs) were used as the heating elements. High-temperature-stable regenerated fiber Bragg gratings were inscribed in HAFs and in standard telecom fibers as temperature sensors. Using in-fiber light as both the heating power source and the interrogation light source, regenerative fiber Bragg grating sensors were used to gauge the heat transfer from an optically powered heating element induced by the gas flow. Reliable gas flow measurements were demonstrated between 0.066 m∕s and 0.66 m∕s from the room temperature to 800°C. This Letter presents a compact, low-cost, and multiflexible approach to measure gas flow for high-temperature harsh environments. Gas flow measurement plays important roles in various industrial sectors. It provides vital information for a large number of applications such as process controls, fossil fuel and nuclear electric power generation, transportation, and environment monitoring. To perform flow measurements, a large number of flow sensors based on various mechanical, electronic, and microelectromechanical system (MEMS) structures [1] have been developed. These sensors can perform effective flow measurements at room temperature or slightly elevated temperatures (e.g., <200°C). However, a number of industrial and aerospace applications demand flow sensors with much higher operational temperatures (>500°C). These are not attainable by current state-of-the-art technology, such as MEMS. To address this technical challenge, this Letter presents a low-cost and compact all-optical-fiber flow sensing technique that can provide rapid and accurate gas flow measurements from room temperature to 800°C. This is, to our best knowledge, the highest operational temperature for a flow sensor. Fiber-optic sensors are well-known for their resilience in many harsh conditions including in high-temperature, corrosive, and strong electromagnetic environments. Over the last decade, various optical-fiber-based flow sensors have been reported, largely based on two schemes: fiber optical interferometry Compared with electrically heated HWA flow sensors, fiber-optic sensors can also be heated optically to perform flow measurements. Using various optical coupling schemes In this Letter, we demonstrate an all-fiber hightemperature flow sensor using the optical HWA rated for 800°C operation. The sensor consists of an in-fiber optical heating element using high-attenuation fibers (HAFs). High-temperature-stable regenerated FBGs (RFBG

Distributed hydrogen sensing using in-fiber Rayleigh scattering

This letter reports a fully distributed hydrogen sensing technique using Rayleigh backscattering in palladium (Pd) and copper (Cu) coated optical fiber. The local in-fiber strain changes due to Pd hydrogen absorptions are interrogated spatially resolved optical frequency domain reflectrometry measurements of the Rayleigh signals. Electrical power is used to induce heating in the Pd coating, which accelerates both the hydrogen response and the sensor recycling. This technique promises an inexpensive and truly distributed fiber solution for continuous hydrogen leak detection with centimeter spatial resolution at room and low temperatures. © 2012 American Institute of Physics

Synergistic effect of CD47 blockade in combination with cordycepin treatment against cancer

Cordycepin is widely considered a direct tumor-suppressive agent. However, few studies have investigated as the effect of cordycepin therapy on the tumor microenvironment (TME). In our present study, we demonstrated that cordycepin could weaken the function of M1-like macrophages in the TME and also contribute to macrophage polarization toward the M2 phenotype. Herein, we established a combined therapeutic strategy combining cordycepin and an anti-CD47 antibody. By using single-cell RNA sequencing (scRNA-seq), we showed that the combination treatment could significantly enhance the effect of cordycepin, which would reactivate macrophages and reverse macrophage polarization. In addition, the combination treatment could regulate the proportion of CD8+ T cells to prolong the progression-free survival (PFS) of patients with digestive tract malignancies. Finally, flow cytometry validated the changes in the proportions of tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs). Collectively, our findings suggested that the combination treatment of cordycepin and the anti-CD47 antibody could significantly enhance tumor suppression, increase the proportion of M1 macrophages, and decrease the proportion of M2 macrophages. In addition, the PFS in patients with digestive tract malignancies would be prolonged by regulating CD8+ T cells

CircRNAs in BALF exosomes and plasma as diagnostic biomarkers in patients with acute respiratory distress syndrome caused by severe pneumonia

BackgroundThe transcriptomic studies targeting circular RNAs (circRNAs) in bronchoalveolar lavage fluid (BALF) exosomes of acute respiratory distress syndrome (ARDS) patients caused by severe pneumonia have rarely been reported. This study aimed to screen and validate abnormally expressed circRNAs in exosomes from BALF of patients with ARDS caused by severe pneumonia and then evaluate the diagnostic values of these circRNAs for ARDS.MethodBALF was collected from four patients with ARDS caused by severe pneumonia and four healthy subjects. CircRNA expression profile was obtained by microarray analysis in BALF exosomes of the discovery cohort. The differentially expressed circRNAs in BALF exosomes were verified by real-time quantitative PCR (RT-qPCR) and underwent competitive endogenous RNA (ceRNA) network construction and functional enrichment analysis.ResultsA total of 629 circRNAs were differentially expressed in BALF exosomes between ARDS patients and healthy subjects. Nine differentially expressed circRNAs were validated by RT-qPCR, and seven were consistent with the results of microarray analysis. CeRNA network analysis was performed for hsa_circRNA_002809, hsa_circRNA_042882, and hsa_circRNA_104034. Functional enrichment analysis showed that the target genes were mainly associated with hypoxia-induced damage, inflammatory response, and the HIF-1 signaling pathway. Hsa_circRNA_042882 and hsa_circRNA_104034 can be regarded as promising diagnostic biomarkers for patients with ARDS caused by severe pneumonia, with remarkable sensitivity and specificity of the area under the curve of 0.8050 and 1 or 0.835 and 0.799, respectively.ConclusionThis study obtained circRNA expression profiles of ARDS patients, and hsa_circRNA_042882 and hsa_circRNA_104034 were regarded as promising diagnostic biomarkers for patients with ARDS caused by severe pneumonia

Combination of transbronchial cryobiopsy based clinic-radiologic-pathologic strategy and metagenomic next-generation sequencing for differential diagnosis of rapidly progressive diffuse parenchymal lung diseases

BackgroundThe complicated spectrum of rapidly progressive diffused parenchymal lung diseases (RP-DPLD) creates obstacles to the precise diagnosis and treatment. We evaluated the differential diagnostic value of transbronchial cryobiopsy (TBCB) based clinic-radiologic-pathologic (CRP) strategy combined with bronchoalveolar lavage fluid (BALF) metagenomic next-generation sequencing (mNGS) in RP-DPLD patients.MethodsRP-DPLD patients who underwent the diagnostic strategy of TBCB-based CRP combined with BALF mNGS at Shanghai East Hospital from May 2020 to Oct 2022 were retrospectively analyzed. Clinical characteristics were summarized, including demographic data, high-resolution computed tomography (HRCT) findings, histopathology of TBCB and microbiological results. Diagnostic value of the combined strategy, as well as the sensitivity, specificity, and positive detection rates of mNGS were evaluated.ResultsA total of 115 RP-DPLD patients were enrolled, with a mean age of 64.4 years old and a male proportion of 54.8%. The pulmonary imaging findings in most patients were complex and diverse, with all patients showing bilateral lung diffuse lesions in HRCT, and progressively aggravated imaging changes within one month. After combining TBCB-based CRP strategy with mNGS, all participants received a corresponding diagnosis with 100% diagnostic yield. In these patients, 58.3% (67/115) were diagnosed with noninfectious RP-DPLD and 41.7% (48/115) with infection-related RP-DPLD. There were 86.1% of cases with known etiology according to the DPLD classification. BALF mNGS and traditional pathogen detection methods were performed in all patients, the positive detection rates were 50.4% (58/115) and 32.2% (37/115), respectively. Meanwhile, the mNGS showed significantly higher sensitivity and negative predictive value than the traditional pathogen detection methods for the diagnosis of infection-related RP-DPLD (100% vs 60.4% (p<0.001), 100% vs 75.6% (p<0.001), respectively). Among noninfectious RP-DPLD patients, the true negative rate of mNGS was 85.1% (57/67). All patients had their treatment regimen modified and the 30-day mortality was 7.0%.ConclusionThe novel strategy of TBCB-based CRP combined with mNGS provided dependable and sufficient evidence for the diagnosis, meanwhile further improved the accuracy of RP-DPLD treatment, as well as the prognosis of patients. Our results highlight the significant value of combined strategy in determining whether the RP-DPLD patients were infection associated or not