Queen bee acid pretreatment attenuates myocardial ischemia/reperfusion injury by enhancing autophagic flux.

Queen bee acid (QBA), which is exclusively found in royal jelly, has anti-inflammatory, antihypercholesterolemic, and antiangiogenic effects. A recent study demonstrated that QBA enhances autophagic flux in the heart. Considering the significant role of autophagy in the development of myocardial ischemia/reperfusion (I/R) injury, we investigated the effect of pretreatment with QBA on myocardial damage. In an in vivo model, left coronary artery blockage for 30 min and reperfusion for 2 h were used to induce myocardial I/R. In an in vitro model, neonatal rat cardiomyocytes (NRCs) were exposed to 3 h of hypoxia and 3 h of reoxygenation (H/R). Our results showed that pretreatment with QBA increased the cell viability of cardiomyocytes exposed to H/R in a dose-dependent manner, and the best protective concentration of QBA was 100 µM. Next, we noted that QBA pretreatment (24h before H/R) enhanced autophagic flux and attenuated mitochondrial damage, cardiac oxidative stress and apoptosis in NRCs exposed to H/R injury, and these effects were weakened by cotreatment with the autophagy inhibitor bafilomycin A1 (Baf). In addition, similar results were observed when QBA (10 mg/kg) was injected intraperitoneally into I/R mice 30 min before ischemia. Compared to mice subjected to I/R alone, those treated with QBA had decreased myocardial infarct area and increased cardiac function, whereas, these effects were partly reversed by Baf. Notably, in NRCs exposed to H/R, tandem fluorescent mRFP-GFP-LC3 assays indicated increased autophagosome degradation due to the increase in autophagic flux upon QBA treatment, but coinjection of Baf blocked autophagic flux. In this investigation, no notable adverse effects of QBA were detected in either cellular or animal models. Our findings suggest that QBA pretreatment mitigates myocardial I/R injury by eliminating dysfunctional mitochondria and reducing reactive oxygen species via promoting autophagic flux.

Spexin inhibits excessive autophagy-induced ferroptosis to alleviate doxorubicin-induced cardiotoxicity by upregulating Beclin 1.

BACKGROUND AND PURPOSE: Doxorubicin is widely used in the treatment of malignant tumours, but doxorubicin-induced cardiotoxicity severely limits its clinical application. Spexin is a neuropeptide that acts as a novel biomarker in cardiovascular disease. However, the effects of spexin on doxorubicin-induced cardiotoxicity is unclear. EXPERIMENTAL APPROACH: We established a model of doxorubicin-induced cardiotoxicity both in vivo and in vitro. Levels of cardiac damage in mice was assessed through cardiac function assessment, determination of serum cardiac troponin T and CKMB levels and histological examination. CCK8 and PI staining were used to assess the doxorubicin-induced toxicity in cultures of cardiomyocytes in vitro. Ferroptosis was assessed using FerroOrange staining, determination of MDA and 4-HNE content and ferroptosis-associated proteins SLC7A11 and GPX4. Mitochondrial membrane potential and lipid peroxidation levels were measured using TMRE and C11-BODIPY 581/591 probes, respectively. Myocardial autophagy was assessed by expression of P62 and Beclin1. KEY RESULTS: Spexin treatment improved heart function of mice with doxorubicin-induced cardiotoxicity, and attenuated doxorubicin-induced cardiotoxicity by decreasing iron accumulation, abnormal lipid metabolism and inhibiting ferroptosis. Interestingly, doxorubicin caused excessive autophagy in cardiomyocyte in culture, which could be alleviated by treatment with spexin. Knockdown of Beclin 1 eliminated the protective effects of spexin in mice with DIC. CONCLUSION AND IMPLICATIONS: Spexin ameliorated doxorubicin-induced cardiotoxicity by inhibiting excessive autophagy-induced ferroptosis, suggesting that spexin could be a drug candidate against doxorubicin-induced cardiotoxicity. Beclin 1 might be critical in mediating the protective effect of spexin against doxorubicin-induced cardiotoxicity.

Fucoxanthin alleviated myocardial ischemia and reperfusion injury through inhibition of ferroptosis via the NRF2 signaling pathway.

Background: Myocardial ischemia and reperfusion injury (MIRI) is a severe complication of revascularization therapy in patients with myocardial infarction. Therefore, there is an urgent requirement to find more therapeutic solutions for MIRI. Recently, ferroptosis, which is characterized by lipid peroxidation, was considered a critical contributor to MIRI. Fucoxanthin (FX), a natural antioxidant carotenoid, which is abundant in brown seaweed, exerts protective effects under various pathological conditions. However, whether FX alleviates MIRI is unclear. This study aims to clarify the effects of FX on MIRI. Methods: Mice with left anterior descending artery ligation and reperfusion were used as in vivo models. Neonatal rat cardiomyocytes (NRCs) induced with hypoxia and reperfusion were used as in vitro models. TTC-Evans blue staining was performed to validate the infarction size. Transmission electron microscopy was employed to detect mitochondrial injury in cardiomyocytes. In addition, 4 weeks after MIRI, echocardiography was performed to measure cardiac function; fluorescent probes and western blots were used to detect ferroptosis. Results: TTC-Evans blue staining showed that FX reduced the infarction size induced by MIRI. Transmission electron microscopy showed that FX ameliorated the MIRI-induced myofibril loss and mitochondrion shrinkage. Furthermore, FX improved LVEF and LVFS and inhibited myocardial hypertrophy and fibrosis after 4 weeks in mice with MIRI. In the in vitro study, calcein AM/PI staining and TUNEL staining showed that FX reduced cell death caused by hypoxia and reperfusion treatment. DCFH-DA and MitoSOX probes indicated that FX inhibited cellular and mitochondrial reactive oxygen species (ROS). Moreover, C11-BODIPY 581/591 staining, ferro-orange staining, MDA assay, Fe2+ assay, 4-hydroxynonenal enzyme-linked immunosorbent assay, and western blot were performed and the results revealed that FX ameliorated ferroptosis in vitro and in vivo, as indicated by inhibiting lipid ROS and Fe2+ release, as well as by modulating ferroptosis hallmark FTH, TFRC, and GPX4 expression. Additionally, the protective effects of FX were eliminated by the NRF2 inhibitor brusatol, as observed from western blotting, C11-BODIPY 581/591 staining, and calcein AM/PI staining, indicating that FX exerted cardio-protective effects on MIRI through the NRF2 pathway. Conclusion: Our study showed that FX alleviated MIRI through the inhibition of ferroptosis via the NRF2 signaling pathway.

Guiding ablation strategies for ventricular tachycardia in patients with structural heart disease by analyzing links and conversion patterns of traceable abnormal late potential zone.

BACKGROUND: Substrate-based ablation can treat uninducible or hemodynamically instability scar-related ventricular tachycardia (VT). However, whether a correlation exists between the critical VT isthmus and late activation zone (LAZ) during sinus rhythm (SR) is unknown. OBJECTIVE: To demonstrate the structural and functional properties of abnormal substrates and analyze the link between the VT circuit and abnormal activity during SR. METHODS: Thirty-six patients with scar-related VT (age, 50.0 ± 13.7 years and 86.1% men) who underwent VT ablation were reviewed. The automatic rhythmia ultrahigh resolution mapping system was used for electroanatomic substrate mapping. The clinical characteristics and mapping findings, particularly the LAZ characteristics during SR and VT, were analyzed. To determine the association between the LAZ during the SR and VT circuits, the LAZ was defined as five activation patterns: entrance, exit, core, blind alley, and conduction barrier. RESULTS: Forty-five VTs were induced in 36 patients, 91.1% of which were monomorphic. The LAZ of all patients was mapped during the SR and VT circuits, and the consistency of the anatomical locations of the LAZ and VT circuits was analyzed. Using the ultrahigh resolution mapping system, interconversion patterns, including the bridge, T, puzzle, maze, and multilayer types, were identified. VT ablation enabled precise ablation of abnormal late potential conduction channels. CONCLUSION: Five interconversion patterns of the LAZ during the SR and VT circuits were summarized. These findings may help formulate more precise substrate-based ablation strategies for scar-related VT and shorter procedure times.

Galangin Attenuates Myocardial Ischemic Reperfusion-Induced Ferroptosis by Targeting Nrf2/Gpx4 Signaling Pathway.

Purpose: Myocardial ischemic reperfusion injury (MIRI) is a crucial clinical problem globally. The molecular mechanisms of MIRI need to be fully explored to develop new therapeutic methods. Galangin (Gal), which is a natural flavonoid extracted from Alpinia Officinarum Hance and Propolis, possesses a wide range of pharmacological activities, but its effects on MIRI remain unclear. This study aimed to determine the pharmacological effects of Gal on MIRI. Methods: C57BL/6 mice underwent reperfusion for 3 h after 45 min of ischemia, and neonatal rat cardiomyocytes (NRCs) subjected to hypoxia and reoxygenation (HR) were cultured as in vivo and in vitro models. Echocardiography and TTC-Evans Blue staining were performed to evaluate the myocardial injury. Transmission electron microscope and JC-1 staining were used to validate the mitochondrial function. Additionally, Western blot detected ferroptosis markers, including Gpx4, FTH, and xCT. Results: Gal treatment alleviated cardiac myofibril damage, reduced infarction size, improved cardiac function, and prevented mitochondrial injury in mice with MIRI. Gal significantly alleviated HR-induced cell death and mitigated mitochondrial membrane potential reduction in NRCs. Furthermore, Gal significantly inhibited ferroptosis by preventing iron overload and lipid peroxidation, as well as regulating Gpx4, FTH, and xCT expression levels. Moreover, Gal up-regulated nuclear transcriptive factor Nrf2 in HR-treated NRCs. Nrf2 inhibition by Brusatol abolished the protective effect of Gal against ferroptosis. Conclusion: This study revealed that Gal alleviates myocardial ischemic reperfusion-induced ferroptosis by targeting Nrf2/Gpx4 signaling pathway.

Research progress on activation transcription factor 3: A promising cardioprotective molecule.

Activation transcription factor 3 (ATF3), a member of the ATF/cyclic adenosine monophosphate response element binding family, can be induced by a variety of stresses. Numerous studies have indicated that ATF3 plays multiple roles in the development and progression of cardiovascular diseases, including atherosclerosis, hypertrophy, fibrosis, myocardial ischemia-reperfusion, cardiomyopathy, and other cardiac dysfunctions. In past decades, ATF3 has been demonstrated to be detrimental to some cardiac diseases. Current studies have indicated that ATF3 can function as a cardioprotective molecule in antioxidative stress, lipid metabolic metabolism, energy metabolic regulation, and cell death modulation. To unveil the potential therapeutic role of ATF3 in cardiovascular diseases, we organized this review to explore the protective effects and mechanisms of ATF3 on cardiac dysfunction, which might provide rational evidence for the prevention and cure of cardiovascular diseases.

Pressure dependence in aqueous-based electrochemical CO2 reduction.

Electrochemical CO2 reduction (CO2R) is an approach to closing the carbon cycle for chemical synthesis. To date, the field has focused on the electrolysis of ambient pressure CO2. However, industrial CO2 is pressurized-in capture, transport and storage-and is often in dissolved form. Here, we find that pressurization to 50 bar steers CO2R pathways toward formate, something seen across widely-employed CO2R catalysts. By developing operando methods compatible with high pressures, including quantitative operando Raman spectroscopy, we link the high formate selectivity to increased CO2 coverage on the cathode surface. The interplay of theory and experiments validates the mechanism, and guides us to functionalize the surface of a Cu cathode with a proton-resistant layer to further the pressure-mediated selectivity effect. This work illustrates the value of industrial CO2 sources as the starting feedstock for sustainable chemical synthesis.

Selective Delivery of Tofacitinib Citrate to Hair Follicles Using Lipid-Coated Calcium Carbonate Nanocarrier Controls Chemotherapy-Induced Alopecia Areata.

Chemotherapy-induced alopecia (CIA) is one of the common side effects in cancer treatment. The psychological distress caused by hair loss may cause patients to discontinue chemotherapy, affecting the efficacy of the treatment. The JAK inhibitor, Tofacitinib citrate (TFC), showed huge potential in therapeutic applications for treating baldness, but the systemic adverse effects of oral administration and low absorption rate at the target site limited its widespread application in alopecia. To overcome these problems, we designed phospholipid-calcium carbonate hybrid nanoparticles (PL/ACC NPs) for a topical application to target deliver TFC. The results proved that PL/ACC-TFC NPs showed excellent pH sensitivity and transdermal penetration in vitro. PL/ACC NPs offered an efficient follicular targeting approach to deliver TFC in a Cyclophosphamide (CYP)-induced alopecia areata mouse model. Compared to the topical application of TFC solution, PL/ACC-TFC NPs significantly inhibited apoptosis of mouse hair follicles and accelerated hair growth. These findings support that PL/ACC-TFC NPs has the potential for topical application in preventing and mitigating CYP-induced Alopecia areata.

Role of nerve signal transduction and neuroimmune crosstalk in mediating the analgesic effects of acupuncture for neuropathic pain.

Neurogenic pain rises because of nervous system damage or dysfunction and is the most difficult to treat among other pathological pains. Acupuncture has been reported as a great treatment option for neurogenic pain owing to its unlimited advantages. However, previous studies on the analgesic effects of acupuncture for NP were scattered and did not form a whole. In this study, we first comprehensively review the relevant basic articles on acupuncture for NP published in the last 5 years and summarize the analgesic mechanisms of acupuncture in terms of nerve signaling, neuro-immune crosstalk, and metabolic and oxidative stress regulation. Acupuncture inhibits the upstream excitatory system and suppresses neuronal transmission efficiency by downregulating glutamate, NMDA receptors, P2XR, SP, CGRP, and other neurotransmitters and receptors in the spinal cord, as well as plasma channels such as TRPV1, HCN. It can also activate the downstream pain inhibitory pathway by upregulating opioid peptide (ß-endorphin), MOR receptors, GABA and GABA receptors, bi-directional regulating 5-hydroxytryptamine (5-HT) and its receptors (upregulate 5-HT 1A and downregulate 5-HT7R) and stimulating hypothalamic appetite-modifying neurons. Moreover, neuroinflammation in pain can be inhibited by acupuncture through inhibiting JAK2/STAT3, PI3K/mTOR pathways, down regulating chemokine receptor CX3CR1 on microglia and up regulating adenosine receptor A1Rs on astrocytes, inhibiting the activation of glia and reducing TNF-α and other inflammatory substances. Acupuncture also inhibits neuronal glucose metabolism by downregulating mPFC's GLUT-3 and promotes metabolic alterations of the brain, thus exerting an analgesic effect. In conclusion, the regulation of nerve signal transduction and neuroimmune crosstalk at the peripheral and central levels mediates the analgesic effects of acupuncture for neuropathic pain in an integrated manner. These findings provide a reliable basis for better clinical application of acupuncture in the management of neuropathic pain.

Fiber-bundle-based 2D Raman and Rayleigh imaging for major species and temperature measurement in laminar flames.

In this Letter, we introduce a novel fiber-bundle-based 2D Raman and Rayleigh imaging system for 2D measurements of major species mole fractions and temperature in flames. A cascade of dichroic mirrors and bandpass filters separate the Raman signal associated with each major species and direct it to a custom-built four-inputs/one-output fiber bundle. The single output of the fiber bundle allows simultaneous detection of four species by using a single back-illuminated CCD camera. The novel imaging system combined with a pulse-burst laser operated at 10 kHz and a 10 kHz optical shutter is characterized from measurements in a Mckenna burner and then applied to a flame stabilized over a Santoro burner. The work is, to the best of our knowledge, the first demonstration of 2D measurements of temperature and major species (i.e., N2, O2, H2, and H2O) in H2-air diffusion flames at atmospheric pressure.

A novel function of ATF3 in suppression of ferroptosis in mouse heart suffered ischemia/reperfusion.

INTRODUCTION: Ferroptosis, a newly identified type of programmed cell death type, has been proven to contribute to the progression of myocardial ischemia/reperfusion (I/R) injury. However, little is known about ferroptosis regulation in I/R injury. OBJECTIVES: We identified activating transcription factor 3 (ATF3) as a vital regulator of I/R induced ferroptosis and investigated the effects and potential mechanism of ATF3 in cardiac ferroptosis. METHODS: In this study, the dynamic RNA-sequencing (RNA-seq) analysis were performed on mouse hearts exposed to different I/R schedules to identify that ATF3 represents an important modulatory molecule in myocardial I/R injury. Then knockout, rescue and overexpression methods were used in mice and neonatal mouse cells (NMCs) to illustrate the effect of ATF3 on myocardial I/R injury. Loss/gain of function techniques were used both in vivo and in vitro to explore the effects of ATF3 on ferroptosis in I/R injury. Furthermore, chromatin immunoprecipitation sequence (ChIP-seq) analysis was performed in the AC16 human cardiomyocyte cell line to investigate potential genes regulated by ATF3. RESULTS: ATF3 expression reached highest level at early stage of reperfusion, knockout of ATF3 significantly aggravated I/R injury, which could be rescued by ATF3 re-expression. Knockout and the re-expression of ATF3 changed the transcription levels of multiple ferroptosis genes. In addition, results showed that overexpression of ATF3 inhibits cardiomyocyte ferroptosis triggered by erastin and RSL3. Lastly, ChIP-seq and dual luciferase activity analysis revealed ATF3 could bind to the transcription start site of Fanconi anaemia complementation group D2 (FANCD2) and increased the FANCD2 promoter activity. Furthermore, we first demonstrated that overexpression of FANCD2 exerts significant anti-ferroptosis and cardioprotective effect on AC16 cell H/R injury. CONCLUSION: ATF3 inhibits cardiomyocyte ferroptotic death in I/R injury, which might be related with regulating FANCD2. Our study provides new insight into the molecular target for the therapy of myocardial I/R injury.

The Clinical Value of Chemotherapy Combined With Capecitabine in Triple-Negative Breast Cancer-A Meta-Analysis.

Purpose: Triple-negative breast cancer (TNBC) is the most dangerous subtype of breast cancer with high rates of metastasis and recurrence. The efficacy of capecitabine in chemotherapy for TNBC is still controversial. This study evaluated the efficacy and safety of capecitabine combining with standard, adjuvant or neoadjuvant chemotherapy for TNBC. Methods: We systematically searched clinical studies through PubMed, Cochrane library, Embase, Wanfang Database, China Academic Journals (CNKI), and American Society of Clinical Oncology's (ASCO) annual conference report. Studies were assessed for design and quality by the Cochrane risk of bias tool. A meta-analysis was performed using Review Manager to quantify the effect of capecitabine combined with standard, adjuvant or neoadjuvant chemotherapy on the disease-free survival (DFS) rate and overall survival (OS) rate of TNBC patients. Furthermore, safety analysis was performed to evaluate the adverse events. Results: Twelve randomized controlled clinical trials involving totally 4854 TNBC patients were included, of which 2,214 patients received chemotherapy as control group, and 2,278 patients received capecitabine combining with chemotherapy. The results indicated that capecitabine could significantly improve the DFS [hazard ratio (HR) 0.80, 95% confidence interval (CI) 0.71-0.90, P = 0.0003] and OS (HR 0.83, 95% CI 0.74-0.93, P = 0.001). In subgroup analysis, the combination of capecitabine and cyclophosphamide exhibited a significant benefit in all outcomes (DFS HR 0.75, 95% CI 0.63-0.90, P = 0.002; OS HR 0.65, 95% CI 0.52-0.80, p < 0.0001). Additionally, defferent dose of capecitabine subgroup showed same significant effect on the results. Safety analysis showed that the addition of capecitabine was associated with a much higher risk of hand-foot syndrome, diarrhea and mucositis or stomatitis. Conclusion: The results showed that adjuvant capecitabine could bring significant benefits on DFS and OS to unselected TNBC patients, the combination of capecitabine and cyclophosphamide could improve the survival rate of patients, although the addition of capecitabine could bring significant side effects such as hand foot syndrome (HFS) and diarrhea.

Temperature dependent Raman spectra of ammonia ranging from 3150 cm-1 to 3810 cm-1 for combustion applications.

Applying in combustion research, Raman scattering technique can provide high accuracy and high precision measurements of temperature and major species concentrations. However detailed knowledge of the temperature dependent Raman spectra of the probed species is a precondition to realise the potential of high precision and accuracy of the technique. As a carbon free novel fuel, the knowledge of high temperature Raman spectra of ammonia is rarely reported. We measured the Raman spectra of ammonia ranging from 299 K to 760 K. The high resolution Raman spectra are excited with a continuous wave 532 nm laser and detected with an low aberration Schmidt-Czerny-Turner spectrometer. The temperature of probe volume was determined by the fitting of N2 Raman spectra. The Raman spectra of ammonia under different temperatures were quantitatively normalized to the same number density to research the temperature behavior of spectra. Within the Raman shift region from 3150 cm-1 to 3810 cm-1, the Raman intensity and the polarization anisotropy of vibrational modes ν1, ν3, and 2ν4 were reported. The relative intensity between ν1, ν3, and 2ν4 modes were also analyzed under different temperatures.

High-speed 1D Raman analyzer for temperature and major species measurements in a combustion environment.

In this Letter, we demonstrate a 5 kHz 1D Raman instrument for temporally and spatially resolved quantitative measurements of temperature and all the major species (N2, O2, H2, and H2O) concentration in H2-air flames. The major constituents of the system are a pulse-burst laser operated at 5 kHz and four back-illuminated CCD cameras operated in subframe burst-gating mode. The use of CCD cameras allows achieving a high sampling rate with no compromise on instrument precision, but it requires one camera for each species of interest. A cascade of dichroic mirrors and bandpass filters spectrally separates the Raman signal associated with each of the four species and directs it to a separate camera. Measurements in a well-characterized H2-air premixed flat flame show that the system has precision comparable with the low-speed Raman system. The measuring uncertainty of the species mole fraction ranges between 1% (N2) and 3∼4% (O2 in lean flames). Measurements in laminar and turbulent H2/N2 jet flames show good agreement with the theoretical prediction. By measuring all species simultaneously, important combustion quantities such as the mixture fraction are also derived.

Impact of input field characteristics on vibrational femtosecond coherent anti-Stokes Raman scattering thermometry.

In this paper, three ultrashort-pulse coherent anti-Stokes Raman scattering (CARS) thermometry approaches are summarized with a theoretical time-domain model. The difference between the approaches can be attributed to variations in the input field characteristics of the time-domain model. That is, all three approaches of ultrashort-pulse (CARS) thermometry can be simulated with the unified model by only changing the input fields features. As a specific example, the hybrid femtosecond/picosecond CARS is assessed for its use in combustion flow diagnostics; thus, the examination of the input field has an impact on thermometry focuses on vibrational hybrid femtosecond/picosecond CARS. Beginning with the general model of ultrashort-pulse CARS, the spectra with different input field parameters are simulated. To analyze the temperature measurement error brought by the input field impacts, the spectra are fitted and compared to fits, with the model neglecting the influence introduced by the input fields. The results demonstrate that, however the input pulses are depicted, temperature errors still would be introduced during an experiment. With proper field characterization, however, the significance of the error can be reduced.

[Temperature Measurement of CH4/Air Premix Flat Flame Based on the Absorption Spectroscopy Technology of UV Tunable Laser].

The physics of combusting flows consists of a complex interaction between chemical reactions, fluid mechanics and radiation. Temperature is one of the most important parameters for the processes. Laser-based imaging techniques are frequently used to assess temperature information from reactive systems without perturbing the system under study. To verify the feasibility of the temperature measurement of UV tunable absorption spectroscopy technology the methane/air premix flat flame was selected as the target of test because of the combustion stability of this kind of flame. Before the temperature measurement the distribution of OH radical in the premix flat flame under different operating conditions were obtained by using planar laser induced fluorescence (PLIF). At the low equivalence ratio the OH radicals distribute uniformly in the flame for the adequate oxygen in the premix gas. The condition with uniform distribution of OH in the flame was selected for the UV tunable absorption spectroscopy measurement. For the selection of absorption lines of the measurement the spectrum of OH A-X(0,0) band have been simulated by LIFBASE. Considering the slope sensitivity and SNR of the test the transitions P1(2) and Q1(8) were suitable for the temperature measurement of the flame. A dye laser pumped by a frequency doubled Nd:YAG laser was used to generated the UV laser. The dye laser was operated with the mixed dye of DCM and PM580 for high conversion efficiency at 310 nm. To investigate the transitions of Q1(8) and P1(2) of OH A-X(0,0) the laser was tuned from 309.225~309.255 and 308.625~308.655 nm separately with the step of 0.4 pm, 30 pulses were recorded at each step. The laser pulses reflected by the beam splitter were collected by detector A, and the pulses passed the flame were collected by detector B. The signal of these two detectors were recorded by the oscilloscope and acquired by the computer automatically. The line shape of these transitions can be obtained after fitting the experimental data with the Voigt function. The integral ratio between the fitting results of these two lines was calculated. Then temperature of the flame could be deduced by the integral ratio. The temperatures of different positions above the surface of burner and varied heights of the flame center were obtained by measuring the integrated absorption ratio of these two transitions. The test results of this method are compared with the report in reference, in which temperature of the burner with the same structure was measured by other ways. The results of these two tests agree well. It shows that this method has the potential to be a calibration for the two-dimension thermometry in flame such as two-line PLIF.

[Research on Real-Time Trace Gas Detection System Based on QEPAS].

Quartz-enhanced photoacoustic spectroscopy (QEPAS) technology was invented lately. Therefore it's an innovative method for trace gas detection compared with other existed technologies. In this paper, we studied the trace gas detection system based on QEPAS, and the atmospheric H2O was selected as the target analyte. In theory, the principles of laser wavelength modulation and signal harmonic detection were analyzed firstly, and the realizing solutions for the gas concentration retrieving and laser wavelength locking were obtained. Furthermore, the selection principle of absorption line for high sensitivity gas detection was discussed. In experiments, a continuous-wave distributed feedback(DFB) single mode diode laser emitting at 1.39 µm was used as the exciting source for the H2O vapor measurement. Using wavelength modulation spectroscopy and 2nd harmonic detection, the influence of laser wavelength modulation depth on QEPAS signal level was investigated, and the acoustic wave enhancement of the addition of micro-resonator in the acoustic detection module was analyzed as well. After optimization of the QEPAS system, a detection limit of 5.9 ppm for H2O vapor was obtained. We measured the H2O vapor with different concentrations, and the R-Square of 0.98 was achieved after the experimental data was linear fitted, indicated that the QEPAS system had an excellent linear response ability. Finally, continuous monitoring of atmospheric H2O concentration levels for a period of 12 hours was performed when the line locking mode was employed with the help of 3rd harmonic detection. The experimental results showed that this QEPAS scheme had a stable performance and outstanding continuous measuring capacity, and it can be widely used in high sensitivity on-line measurement for other trace gases detection fields.

A high spectral sensitivity interferometer based on the dispersive property of the semiconductor GaAs.

We develop an interferometer which has high spectral sensitivity based on the dispersive property of the semiconductor GaAs in the near-infrared region. Our experiment demonstrates that the spectral sensitivity could be greatly enhanced by adding a slow light medium into the interferometer and is proportional to the group index of the material. Subsequently the factors which influence the spectral sensitivity of the interferometer are analyzed. Moreover, we provide potential applications of such interferometers using the dispersive property of semiconductor in whole infrared region.