STING Contributes to Pulmonary Hypertension by Targeting the Interferon and BMPR2 Signaling through Regulating F2RL3.

Pulmonary hypertension (PH) is an incurable disease characterized by pulmonary vascular remodeling. Endothelial injury and inflammation are the key triggers of the disease initiation. Recent findings suggest that STING (stimulator of interferon genes) activation plays a critical role in the endothelial dysfunction and interferon signaling. Here, we investigated the involvement of STING in the pathogenesis of PH. PH patients and rodent PH model samples, Sugen5416/hypoxia (SuHx) PH model, and pulmonary artery endothelial cells (PAECs) were used to evaluate the hypothesis. We found that the cyclic GMP-AMP (cGAS)-STING signaling pathway was activated in the lung tissues from rodent PH models and PH patients, and in the TNF-α induced PAECs in vitro. Specifically, STING expression was significantly elevated in the endothelial cell in PH disease settings. In SuHx mouse model, genetic knockout or pharmacological inhibition of STING prevented the progression of PH. Functionally, knockdown of STING reduced the proliferation and migration in PAECs. Mechanistically, STING transcriptional regulates its binding partner F2RL3 through STING-NF-κB axis, which activated the interferon signaling and repressed the BMPR2 signaling both in vitro and in vivo. Further analysis revealed that F2RL3 expression was increased in PH settings and identified negative feedback regulation of F2RL3/BMPR2 signaling. Accordingly, a positive correlation of expression levels between STING and F2RL3/interferon-stimulated genes (ISGs) was observed in vivo. Our findings suggest that STING activation in PAECs plays a critical role in the pathobiology of PH. Targeting STING may be a promising therapeutic strategy for preventing the development of PH.

2 W, 1.5†µm single-mode fiber methane Raman laser pumped by a Yb-doped fiber amplifier.

We report here, to the best of our knowledge, the first 1.5 µm methane-filled fiber Raman laser pumped by a fiber laser. Based on the narrow-linewidth pulsed Yb-doped fiber laser pump source and a 15 m hollow-core fiber filled with 2.5 bar methane, the maximum power of 2.06 W Stokes wave at 1543 nm is obtained. The output laser has a narrow linewidth of 2.3 GHz, and the pulse repetition frequency can be adjusted flexibly. The output shows excellent near-diffraction-limited beam quality with a M2 factor of ∼1.09. This work proves the advantage of the fiber laser pump source with modest peak power and flexible temporal characteristics in 1.5 µm fiber gas Raman laser emission, providing good guidance for generating pulsed fiber source with narrow linewidth and high beam quality.

Classification, detection, and segmentation performance of image-based AI in intracranial aneurysm: a systematic review.

BACKGROUND: The detection and management of intracranial aneurysms (IAs) are vital to prevent life-threatening complications like subarachnoid hemorrhage (SAH). Artificial Intelligence (AI) can analyze medical images, like CTA or MRA, spotting nuances possibly overlooked by humans. Early detection facilitates timely interventions and improved outcomes. Moreover, AI algorithms offer quantitative data on aneurysm attributes, aiding in long-term monitoring and assessing rupture risks. METHODS: We screened four databases (PubMed, Web of Science, IEEE and Scopus) for studies using artificial intelligence algorithms to identify IA. Based on algorithmic methodologies, we categorized them into classification, segmentation, detection and combined, and then their merits and shortcomings are compared. Subsequently, we elucidate potential challenges that contemporary algorithms might encounter within real-world clinical diagnostic contexts. Then we outline prospective research trajectories and underscore key concerns in this evolving field. RESULTS: Forty-seven studies of IA recognition based on AI were included based on search and screening criteria. The retrospective results represent that current studies can identify IA in different modal images and predict their risk of rupture and blockage. In clinical diagnosis, AI can effectively improve the diagnostic accuracy of IA and reduce missed detection and false positives. CONCLUSIONS: The AI algorithm can detect unobtrusive IA more accurately in communicating arteries and cavernous sinus arteries to avoid further expansion. In addition, analyzing aneurysm rupture and blockage before and after surgery can help doctors plan treatment and reduce the uncertainties in the treatment process.

Numerical simulation and observed rotational relaxation in CW and pulsed HBr-filled hollow-core fiber lasers.

Gas-filled hollow-core fiber (HCF) lasers have emerged as a promising technology for generating mid-infrared lasers. A four-energy level system laser model is presented to predict the performance of optically pumped HBr-filled HCF lasers under continuous wave (CW) and pulsed excitations. The steady state condition is considered in CW pumping and the characteristics of simulated population density and power distribution along HCF are investigated. The finite-difference time-domain method is employed in pulsed pumping and the simulated evolutions of pump pulse and laser pulse at different positions along the HCF are studied. In addition, the phenomena of rotational relaxation in HBr-filled HCF lasers are investigated experimentally for the first time, to the best of our knowledge, showing that using the absorption lines away from the strongest absorption lines and tuning the pump wavelength deviating from the center of the absorption line makes the rotational relaxation occur easily. The demonstration is conductive to reveal the underlying mechanism of such gas-filled HCF lasers.

High power mid-infrared fiber amplifier at 3.1†µm by acetylene-filled hollow-core fibers.

We characterized high-power continuous-wave (CW) and pulsed mid-infrared (mid-IR) fiber amplifiers at a wavelength of 3.1 µm in acetylene-filled hollow-core fibers (HCFs) with a homemade seed laser. A maximum CW power of 7.9 W was achieved in a 4.2-m HCF filled with 4-mbar acetylene, which was 11% higher than the power without the seed. The maximum average power of the pulsed laser was 8.6 W (pulse energy of 0.86 µJ) at 7-mbar acetylene pressure, a 16% increase over the power without the seed. To the best of our knowledge, backward characteristics are reported for the first time for fiber gas lasers, and the backward power accounted for less than 5% of the forward power. The optimum acetylene pressure and HCF length for the highest mid-IR output are discussed based on theoretical simulations. This study provides significant guidance for high-power mid-infrared (mid-IR) output in gas-filled HCFs.

2.3-µm single-frequency Tm: ZBLAN fiber amplifier with output power of 1.41 W.

We present here the first watt-level single-frequency thulium-doped ZBLAN fiber amplifier system operating at a wavelength of 2.3 µm. Continuous-wave output of up to 1.41 W was generated from a two-stage Tm: ZBLAN fiber amplifier with direct ground-state pumping at 793 nm. Seeded by a single-frequency distributed feedback diode laser at 2332 nm, the thulium-doped ZBLAN fiber amplifier emitted a laser with linewidth no more than 10 MHz at maximal output power. This study examines the impact of a 2.3-µm seed on the competitive laser transition of 2 µm. The findings indicate that direct pumping of a Tm fiber amplifier holds the potential for achieving higher power output within the 2.3-µm band.

High-gain single-frequency Tm3+-doped ZBLAN fiber amplifier at 2.33 µm.

We report here, to the best of our knowledge, the first high-gain, single-frequency Tm3+-doped fiber amplifier operating at the 2.3-µm band with conventional ground-state pumping transition (3H6→3H4) at 793 nm. The gain fiber is an 8.5-m-long ZBLAN fiber with a Tm3+ doping concentration of 3 mol.%, and the seed is a single-frequency distributed feedback diode laser operated at 2331.9 nm. A gain up to 24.1 dB is generated for ∼14 W of launched pump power with the maximum output power of 246 mW. The competitive 3F4 →3H6 laser transition at ∼2 µm is also investigated, and the prospects for further power scaling are discussed.

Mid-infrared fiber gas amplifier in acetylene-filled hollow-core fiber.

We report here the first, to the best of our knowledge, demonstration of a mid-infrared (mid-IR) fiber gas amplifier based on acetylene-filled hollow-core fibers. A quasi-all-fiber structure fiber acetylene laser in a single-pass configuration is used as a seed. The injection of the seed removes the threshold and increases the laser efficiency, which are more pronounced at high pressure. In a 3.1-m HCF filled with 2.5 mbar of acetylene, the fiber gas amplifier shows a conversion efficiency (relative to the coupled pump power) of 22.2% at 3.1 µm, which is increased by 35% compared with that without the seed. Both the seed laser and the amplifier laser have good beam quality with M2 < 1.1. It is predictable that such a fiber gas amplifier can achieve a more efficient and higher power mid-IR output for other selected molecular species compared with the single-pass structure, which is beneficial to the development of high-power mid-IR fiber gas lasers.

Fiber laser source of 8 W at 3.1 µm based on acetylene-filled hollow-core silica fibers.

We report here the characteristics of a nanosecond high-power mid-infrared (mid-IR) light source based on an anti-resonant hollow-core fiber (AR-HCF) filled with acetylene gas. It is a single-pass configuration with 9.3-m HCFs, pumped by a modulated and amplified diode laser. A maximum average power of approximately 8 W (pulse energy of ∼0.8 µJ and peak power of ∼40 W) at 3.1 µm is achieved with a laser slope efficiency of ∼22.8% at 6 mbar of acetylene, which is, to the best of our knowledge, a record output power for such mid-IR HCF lasers. This work demonstrates the great potential of fiber gas lasers for high-power output in the mid-IR.

3.1†W mid-infrared fiber laser at 4.16†µm based on HBr-filled hollow-core silica fibers.

We present the characteristics of a continuous-wave (CW) mid-infrared fiber laser source based on HBr-filled hollow-core fibers (HCFs) made of silica. The laser source delivers a maximum output power of 3.1 W at 4.16 µm, showing a record value for any reported fiber laser beyond 4 µm. Both ends of the HCF are supported and sealed by especially designed gas cells with water cooling and inclined optical windows, withstanding higher pump power accompanied by accumulated heat. The mid-infrared laser exhibits a near-diffraction-limited beam quality with a measured M2 of 1.16. This work paves the way for powerful mid-infrared fiber lasers beyond 4 µm.

All-fiber gas Raman laser oscillator.

Here, we report the first, to the best of our knowledge, all-fiber gas Raman laser oscillator (AFGRLO), which is formed by fusion splicing solid-core fibers and a hydrogen-filled hollow-core photonic crystal fiber, and further introducing fiber Bragg gratings at a Stokes wavelength. Pumping with a homemade 1.54 µm fiber amplifier seeded by a narrow linewidth diode laser, we obtain the maximum output Stokes power of 1.8 W at 1693 nm by rotational stimulated Raman scattering of hydrogen molecules. Due to the involvement of the resonant cavity, the measured Raman threshold is as low as 0.98 W, which has been reduced nearly 20 times, compared with that of the single-pass structure. Moreover, a numerical model of an AFGRLO is established for the first time, to the best of our knowledge, and the simulations agree well with the experimental results. This Letter is significant for the development of fiber gas Raman lasers (FGRLs), particularly for achieving compact CW FGRLs towards the mid-infrared.

Narrow-Linewidth 2 µm All-Fiber Laser Amplifier with a Highly Stable and Precisely Tunable Wavelength for Gas Molecule Absorption in Photonic Crystal Hollow-Core Fibers.

In recent years, mid-infrared fiber lasers based on gas-filled photonic crystal hollow-core fibers (HCFs) have attracted enormous attention. They provide a potential method for the generation of high-power mid-infrared emissions, particularly beyond 4 µm. However, there are high requirements of the pump for wavelength stability, tunability, laser linewidth, etc., due to the narrow absorption linewidth of gases. Here, we present the use of a narrow-linewidth, high-power fiber laser with a highly stable and precisely tunable wavelength at 2 µm for gas absorption. It was a master oscillator power-amplifier (MOPA) structure, consisting of a narrow-linewidth fiber seed and two stages of Thulium-doped fiber amplifiers (TDFAs). The seed wavelength was very stable and was precisely tuned from 1971.4 to 1971.8 nm by temperature. Both stages of the amplifiers were forward-pumping, and a maximum output power of 24.8 W was obtained, with a slope efficiency of about 50.5%. The measured laser linewidth was much narrower than the gas absorption linewidth and the wavelength stability was validated by HBr gas absorption in HCFs. If the seed is replaced, this MOPA laser can provide a versatile pump source for mid-infrared fiber gas lasers.

Pure rotational stimulated Raman scattering in H2-filled hollow-core photonic crystal fibers.

We conducted comprehensive theoretical research on rotational stimulated Raman scattering (SRS) of hydrogen molecules in hollow-core fibers. A reliable model for describing the steady-state rotational SRS of hydrogen was established and the influences of various factors was investigated. To verify the theoretical model, a single-pass fiber gas Raman laser (FGRL) based on hydrogen-filled hollow-core photonic crystal fibers pumped by a 1.5 µm nanosecond-pulsed fiber amplifier was constructed. Experimental results were congruent with simulation results. As the output powers and pulse shapes can be well calculated, the model can offer guidance for FGRL investigation, particularly for achieving high-efficiency and high-power FGRLs.

Seasonal and spatial distributions of morpho-functional phytoplankton groups and the role of environmental factors in a subtropical river-type reservoir.

Phytoplankton is capable of responding to aquatic conditions and can therefore be used to monitor freshwater reservoir water quality. Numerous classification techniques, including morpho-functional approaches, have been developed. This study examined changes in phytoplankton assemblages and water quality, which were sampled quarterly from July 2018 to April 2019. The purpose was to contrast the applicability of three classification approaches (functional, morpho-functional and morphological-based functional groupings) for understanding the spatial and seasonal distribution of the biomass variance in phytoplankton functional groups and their driving environmental factors in the ecological zones of the Shanxi Reservoir through multivariate analysis. The results showed that the phytoplankton biomass was highest in the watercourse zone and lowest in the transition zone. Furthermore, the Shanxi Reservoir was characterized by several cyanobacteria (Microcystis spp.) and numerous bacillariophytes (Asterionella sp., Navicula spp. and Aulacoseira granulata). After evaluating the advantages and disadvantages of morpho-functional classifications, we determined that water temperature appeared to be an essential factor, and the morphology-based functional group approach provided the best results for demonstrating phytoplankton succession, despite having lower sensitivity than the others. Nevertheless, these approaches are all appropriate for identifying and monitoring phytoplankton community structure in aquatic systems of reservoirs with complex terrains.

High-efficiency laser wavelength conversion in deuterium-filled hollow-core photonic crystal fiber by rotational stimulated Raman scattering.

We report here, to the best of our knowledge, for the first time high-efficiency laser wavelength conversion from 1.5 µm band to 1.7 µm band in deuterium-filled hollow-core photonic crystal fibers by rotational stimulated Raman scattering (SRS). Due to the special transmission properties of this low-loss hollow-core fiber, the ordinary dominant vibrational SRS is suppressed, permitting efficient conversion to the rotational stokes wave in a single-pass configuration pumped by a fiber amplified and modulated tunable 1.55 µm diode laser. Using proper pump pulse energy and gas pressure, the power conversion efficiencies over the whole output laser wavelength range from 1640 nm to 1674 nm are higher than 48%. And the maximum Raman conversion efficiency of 61.2% is achieved with 20 m fiber and 20 bar deuterium pressure pumped at 1540 nm, giving a maximum average power of about 0.8 W (pulse energy of 1.6 µJ). This work points to a new way for engineerable and compact fiber lasers operation at 1.7 µm band, which has significant applications in biological imaging, laser medical treatment, material processing and detecting.

Low-loss coupling from single-mode solid-core fibers to anti-resonant hollow-core fibers by fiber tapering technique.

We demonstrate here for the first time, to the best of our knowledge, an effective method to achieve low-loss light coupling from solid-core fibers to anti-resonant hollow-core fibers (AR-HCFs) by fiber tapering technique. We establish the coupling models by beam propagation method (BPM), and the simulation results show that the coupling efficiency can be optimized by choosing a proper waist diameter of the tapered solid-core fiber. Two types of AR-HCFs have been tested experimentally, and the maximum light coupling efficiency is ∼91.4% at 1.06 µm and ∼90.2% at 1.57 µm for the ice-cream AR-HCF, and ∼83.7% at 1.57 µm for the node-less AR-HCF. This work provides a feasible low-loss light coupling scheme for AR-HCFs, which is very useful for implementing all fiber systems.

High-power tunable mid-infrared fiber gas laser source by acetylene-filled hollow-core fibers.

High-power tunable pulsed and CW mid-infrared fiber gas laser sources in acetylene-filled hollow-core fibers, to the best of our knowledge, are demonstrated for the first time. By precisely tuning the wavelength of the pump source, an amplified tunable 1.5 µm diode laser, to match different absorption lines of acetylene, the laser output is step-tunable in the range of 3.09~3.21 µm with a maximum pulse average power of ~0.3 W (~0.6 µJ pulse energy) and a maximum CW power of ~0.77 W, making this system the first watt-level tunable fiber gas laser operating at mid-infrared range. The output spectral and power characteristics are systemically studied, and the explanations about the change of the ratio of the P over R branch emission lines with the pump power and the gas pressure are given, which is useful for the investigations of mid-infrared fiber gas lasers.

Watt-level tunable 1.5 µm narrow linewidth fiber ring laser based on a temperature tuning π-phase-shifted fiber Bragg grating.

A watt-level tunable 1.5 µm narrow linewidth fiber ring laser using a temperature tuning π-phase-shifted fiber Bragg grating (π-PSFBG) is demonstrated here, to the best of our knowledge, for the first time. The π-PSFBG is employed as both a narrow band filter and a wavelength tuning component, and its central wavelength is thermally tuned by a thermo-electric cooler. The maximum laser power is about 1.1 W with a linewidth of ∼318 MHz (∼2.57 pm) and a power fluctuation of less than 3%. The wavelength tuning range of the laser is about 1.29 nm with a sensitivity of ∼14.33 pm/°C, and the wavelength fluctuation is about 0.2 pm. This work provides important reference for tunable fiber lasers with both high power and narrow linewidth.

Cascaded All-Fiber Gas Raman Laser Oscillator in Deuterium-Filled Hollow-Core Photonic Crystal Fibers.

Hollow-core photonic crystal fibers (HC-PCFs) provide an ideal transmission medium and experimental platform for laser-matter interaction. Here, we report a cascaded all-fiber gas Raman laser based on deuterium (D2)-filled HC-PCFs. D2 is sealed into a gas cavity formed by a 49 m-long HC-PCF and solid-core fibers, and two homemade fiber Bragg gratings (FBGs) with the Raman and pump wavelength, respectively, are further introduced. When pumped by a pulsed fiber amplifier at 1540 nm, the pure rotational stimulated Raman scattering of D2 occurs inside the cavity. The first-order Raman laser at 1645 nm can be obtained, realizing a maximum power of ~0.8 W. An all-fiber cascaded gas Raman laser oscillator is achieved by adding another 1645 nm high-reflectivity FBG at the output end of the cavity, reducing the peak power of the cascaded Raman threshold by 11.4%. The maximum cascaded Raman power of ~0.5 W is obtained when the pump source is at its maximum, and the corresponding conversion efficiency inside the cavity is 21.4%, which is 1.8 times that of the previous configuration. Moreover, the characteristics of the second-order Raman lasers at 1695 nm and 1730 nm are also studied thoroughly. This work provides a significant method for realizing all-fiber cascaded gas Raman lasers, which is beneficial for expanding the output wavelength of fiber gas lasers with a good stability and compactivity.