Optimized adaptation algorithms for low-complexity adaptive equalizers.

In order to address the high-power consummation issue of conventional multi-input and multi-output (MIMO) adaptive equalizer (AEQ) for short-reach coherent transmissions, several state-of-the-art low-complexity AEQs have been proposed. In our work, optimized adaptation algorithms for low-complexity real-valued (RV) AEQs with different structures are analyzed. Moreover, an approach to avoid introducing additional computational complexity due to the optimized adaptation process is presented here. The advantages of proposed optimized adaptation algorithms are experimentally demonstrated in a 25 Gbaud dual-polarization 16-quadrature-amplitude-modulation (DP-16QAM) back-to-back (BtB) intradyne system with an overall bandwidth of 14 GHz. Experimental results show that a similar performance as the conventional AEQ could be achieved by using proposed adaptation algorithms and reducing the number of multiplications with up to ∼65%.

Fast gas sensing scheme with multi-component gas measurement capacity based on non-dispersive frequency comb spectroscopy (ND-FCS).

A fast gas sensing scheme based on a non-dispersive frequency comb spectroscopy (ND-FCS) is proposed and experimentally demonstrated. Its capacity for multi-component gas measurement is experimentally investigated as well, by using the time-division-multiplexing (TDM) method to realize specific wavelength selection of the fiber laser optical frequency comb (OFC). A dual-channel optical fiber sensing scheme is established with a sensing path consisting of a multi-pass gas cell (MPGC), and a reference path with a calibrated signal to track the repetition frequency drift of the OFC for a real-time lock-in compensation and system stabilization. The long-term stability evaluation and the simultaneous dynamic monitoring are carried out, with the target gases of ammonia (NH3), carbon monoxide (CO) and carbon dioxide (CO2). The fast CO2 detection in human breath is also conducted. The experimental results show that at an integration time of 10 ms, the detection limits of the three species are evaluated to be 0.0048%, 0.1869% and 0.0467%, respectively. A low minimum detectable absorbance (MDA) down to 2.8 × 10-4 can be achieved and a dynamic response with millisecond time can be realized. Our proposed ND-FCS exhibits excellent gas sensing performance with merits of high sensitivity, fast response and long-term stability. It also shows great potential for multi-component gas monitoring in atmospheric monitoring applications.

High-performance towing cable hydrophone array with an improved ultra-sensitive fiber-optic distributed acoustic sensing system.

A high-performance towing cable hydrophone array based on an improved ultra-sensitive fiber-optic distributed acoustic sensing system (uDAS) with picostrain sensitivity is demonstrated and tested in sea trial, for the first time. A new composite transducer is designed and optimized to enhance the acoustic pressure sensitivity significantly. A sea trial is carried out to test the performances of such a hydrophone array, including flow noise, underwater acoustic signal capture capacity, beamforming processing and localization of artificial source targets. The array exhibits high sensitivity and low noise floor. An average sensitivity of -129.23 dB re rad/µPa at frequencies from 10 Hz to 1500 Hz has been achieved. The localization at distances of 5 km and 10 km is realized, respectively, validating the excellent remote detection and positioning capability of the hydrophone system. The proposed towing cable system, with high sensitivity, simple structure and remote target localization ability, may pave a way for development of the next generation of high-performance light-weighting hydrophone arrays for towing applications.

Single-carrier 800-Gb/s self-homodyne coherent transmission of DP-16QAM, DP-32QAM, and DP-64QAM with uncooled DFB laser.

Self-homodyne detection (SHD) is a promising approach to realize high-capacity short-reach optical transmission systems with low cost and low power consumption. We experimentally demonstrate single-carrier net 800-Gb/s SHD transmission with low-cost ∼MHz linewidth distributed feedback (DFB) laser over 2 km, 10 km, 25 km, and 40 km single-mode fiber (SMF) using three different quadrature amplitude modulation (QAM) formats, including 80-Gbaud dual-polarization (DP) 64QAM, 100-Gbaud DP-32QAM, and 120-Gbaud DP-16QAM. Among them, net 800-Gb/s DP-64QAM SHD transmission over 25 km SMF using an uncooled DFB laser with a linewidth of 2.6 MHz is experimentally verified. The detailed experimental performance evaluation of net 800Gb/s SHD system is performed, in which various configurations are considered, such as different laser linewidths, three QAM formats, and different transmission distances. DFB lasers with linewidths of 1 MHz and 2.6 MHz lead to negligible penalty when compared to the same SHD system but using an external cavity laser (ECL) with a linewidth of 26kHz in back-to-back (BTB) case. 80-Gbaud DP-64QAM obtains the highest optical signal-to-noise ratio (OSNR) requirement and the highest bit-error rate (BER) floor but the best tolerance of chromatic dispersion (CD). 120-Gbaud DP-16QAM achieves the lowest OSNR requirement and the lowest BER floor but the worst tolerance of CD. The detailed experimental investigation is conducive to promote the practical application of SHD in different short-reach scenarios.

ICI 182,780 Attenuates Selective Upregulation of Uterine Artery Cystathionine ß-Synthase Expression in Rat Pregnancy.

Endogenous hydrogen sulfide (H2S) produced by cystathionine ß-synthase (CBS) and cystathionine-γ lyase (CSE) has emerged as a novel uterine vasodilator contributing to pregnancy-associated increases in uterine blood flow, which safeguard pregnancy health. Uterine artery (UA) H2S production is stimulated via exogenous estrogen replacement and is associated with elevated endogenous estrogens during pregnancy through the selective upregulation of CBS without altering CSE. However, how endogenous estrogens regulate uterine artery CBS expression in pregnancy is unknown. This study was conducted to test a hypothesis that endogenous estrogens selectively stimulate UA CBS expression via specific estrogen receptors (ER). Treatment with E2ß (0.01 to 100 nM) stimulated CBS but not CSE mRNA in organ cultures of fresh UA rings from both NP and P (gestational day 20, GD20) rats, with greater responses to all doses of E2ß tested in P vs. NP UA. ER antagonist ICI 182,780 (ICI, 1 µM) completely attenuated E2ß-stimulated CBS mRNA in both NP and P rat UA. Subcutaneous injection with ICI 182,780 (0.3 mg/rat) of GD19 P rats for 24 h significantly inhibited UA CBS but not mRNA expression, consistent with reduced endothelial and smooth muscle cell CBS (but not CSE) protein. ICI did not alter mesenteric and renal artery CBS and CSE mRNA. In addition, ICI decreased endothelial nitric oxide synthase mRNA in UA but not in mesenteric or renal arteries. Thus, pregnancy-augmented UA CBS/H2S production is mediated by the actions of endogenous estrogens via specific ER in pregnant rats.

High energy and low noise soliton fiber laser comb based on nonlinear merging of Kelly sidebands.

Optical solitons in mode-locked laser cavities with dispersion-nonlinearity interaction, delivers pulses of light that retain their shape. Due to the nature of discretely distributed dispersion and nonlinearity, optical solitons can emit Kelly-sidebands via the frequency coupling of soliton and dispersive waves. In this paper, we generate a high-energy femtosecond laser comb, by using the intracavity Kelly radiations and 3rd order nonlinearities. By increasing the intracavity power, the soliton envelop and the Kelly-sidebands merge together via four-wave-mixing, forming a super-continuum spectrum, obtaining 3.18 nJ pulse energy. A supercontinuum span covering from 1100 nm to 2300 nm for further self-referenced f-2f stabilization can be directly achieved by using an amplification-free external supercontinuum technique. Our finding not only demonstrates a non-trivial frequency-time evolution based on 'erbium + χ(3)' nonlinear gains, but also offers a new opportunity to develop practically compact fiber frequency combs for frequency metrology or spectroscopy.

Shaoyao-Gancao Decoction Promoted Microglia M2 Polarization via the IL-13-Mediated JAK2/STAT6 Pathway to Alleviate Cerebral Ischemia-Reperfusion Injury.

Microglia in the penumbra shifted from M2 to M1 phenotype between 3 and 5 days after cerebral ischemia-reperfusion, which promoted local inflammation and injury. Shaoyao-Gancao Decoction (SGD) has been found to result in a significant upregulation of IL-13 in the penumbra, which has been shown to induce polarization of M2 microglia. There was thus a hypothesis that SGD could exert an anti-inflammatory and neuroprotective effect by activating IL-13 to induce microglia polarization towards M2 phenotype, and the purpose of this study was to explore the influence of SGD on microglia phenotype switching and its possible mechanism. Rats who received middle cerebral artery occlusion surgery (MCAO) were treated with SGD for 3 or 6 days, to investigate the therapeutic effect and the underlying mechanism of SGD for cerebral ischemia-reperfusion injury (CI/RP). The results indicated that SGD improved neurobehavioral scores and reduced apoptosis. Furthermore, SGD significantly decreased M1 microglia and M1-like markers, but increased M2 microglia and M2 markers. Moreover, higher levels of IL-13 and ratios of p-JAK2/JAK2 and p-STAT6/STAT6 were found in the SGD group compared to the MCAO. In conclusion, it was verified that SGD prevented injury by driving microglia phenotypic switching from M1 to M2, probably via IL-13 and its downstream JAK2-STAT6 pathway. Given that no further validation tests were included in this study, it is necessary to conduct more experiments to confirm the reliability of the above results.

High-Sensitivity, Quantified, Linear and Mediator-Free Resonator-Based Microwave Biosensor for Glucose Detection.

This article presents a high-sensitivity, quantified, linear, and mediator-free resonator-based microwave biosensor for glucose sensing application. The proposed biosensor comprises an air-bridge-type asymmetrical differential inductor (L) and a center-loaded circular finger-based inter-digital capacitor (C) fabricated on Gallium Arsenide (GaAs) substrate using advanced micro-fabrication technology. The intertwined asymmetrical differential inductor is used to achieve a high inductance value with a suitable Q-factor, and the centralized inter-digital capacitor is introduced to generate an intensified electric field. The designed microwave sensor is optimized to operate at a low resonating frequency that increases the electric field penetration depth and interaction area in the glucose sample. The microwave biosensor is tested with different glucose concentrations (0.3-5 mg/ml), under different ambient temperatures (10-50 °C). The involvement of advanced micro-fabrication technology effectively miniaturized the microwave biosensor (0.006λ0 × 0.005λ0) and enhanced its filling factor. The proposed microwave biosensor demonstrates a high sensitivity of 117.5 MHz/mgmL-1 with a linear response (r2 = 0.9987), good amplitude variation of 0.49 dB/mgmL-1 with a linear response (r2 = 0.9954), and maximum reproducibility of 0.78% at 2 mg/mL. Additionally, mathematical modelling was performed to estimate the dielectric value of the frequency-dependent glucose sample. The measured and analyzed results indicate that the proposed biosensor is suitable for real-time blood glucose detection measurements.

An Ethanol Vapor Sensor Based on a Microfiber with a Quantum-Dot Gel Coating.

An ethanol vapor sensor based on a microfiber with a quantum-dot (QD) gel coating is proposed and demonstrated. The QD gel was made from UV glue as the gel matrix and CdSe/ZnS QDs with a concentration of 1 mg/mL. The drawing and coating processes were conducted by using a simple and low-cost system developed for this study. Bending, ethanol sensing, temperature response, and time response tests were carried out, respectively. The experimental results showed that the fabricated sensor had a high sensitivity of -3.3%/ppm, a very low temperature cross-sensitivity of 0.17 ppm/°C, and a fast response time of 1.1 s. The easily fabricated robust structure and the excellent sensing performance render the sensor a promising platform for real ethanol sensing applications.

Liquid-level sensing based on a hollow core Bragg fiber.

A novel optical fiber liquid level sensor based on a hollow core Bragg fiber (HCBF) was proposed and demonstrated. The HCBF was first designed and successfully fabricated with periodic transmission band in the spectrum and a transmission loss of ~3.48 dB/cm. An inline optical fiber liquid-level sensor was fabricated by simply sandwiching a piece of HCBF between two single mode fibers. The sensing performance was experimentally tested. A linear liquid-level sensitivity of ~1.1 dB/mm, and fast response time less than 3s was obtained by the intensity demodulation measurement. The temperature and refractive index cross-sensitivities were also investigated. The experimental results indicate that our proposed structure has tiny temperature and RI dependence, which makes it a promising liquid level sensing platform for different liquids.

Intratracheal administration of adipose derived mesenchymal stem cells alleviates chronic asthma in a mouse model.

BACKGROUND: Adipose-derived mesenchymal stem cell (ASCs) exerts immunomodulatory roles in asthma. However, the underlying mechanism remains unclear. The present study aimed to explore the effects and mechanisms of ASCs on chronic asthma using an ovalbumin (OVA)-sensitized asthmatic mouse model. METHODS: Murine ASCs (mASCs) were isolated from male Balb/c mice and identified by the expression of surface markers using flow cytometry. The OVA-sensitized asthmatic mouse model was established and then animals were treated with the mASCs through intratracheal delivery. The therapy effects were assessed by measuring airway responsiveness, performing immuohistochemical analysis, and examining bronchoalveolar lavage fluid (BALF). Additionally, the expression of inflammatory cytokines and lgE was detected by CHIP and ELISA, respectively. The mRNA levels of serum indices were detected using qRT-PCR. RESULTS: The mASCs grew by adherence with fibroblast-like morphology, and showed the positive expression of CD90, CD44, and CD29 as well as the negative expression of CD45 and CD34, indicating that the mASCs were successfully isolated. Administering mASCs to asthmatic model animals through intratracheal delivery reduced airway responsiveness, the number of lymphocytes (P < 0.01) and the expression of lgE (P < 0.01), IL-1ß (P < 0.05), IL-4 (P < 0.001), and IL-17F (P < 0.001), as well as increased the serum levels of IL-10 and Foxp3, and the percentage of CD4 + CD25 + Foxp3+ Tregs in the spleen, and reduced the expression of IL-17 (P < 0.05) and RORγ. CONCLUSIONS: Intratracheal administration of mASCs alleviated airway inflammation, improved airway remodeling, and relieved airway hyperresponsiveness in an OVA-sensitized asthma model, which might be associated with the restoration of Th1/Th2 cell balance by mASCs.

Terahertz polarization splitter based on a dual-elliptical-core polymer fiber.

A terahertz polarization splitter based on a dual-elliptical-core polymer fiber is proposed and theoretically optimized. Dual-elliptical cores with subwavelength-scale diameters are independently suspended within a fiber, which not only support two orthogonal polarization modes, being single-mode guided with low absorption losses, but also allow them to switch from one core to the other, with different coupling lengths. As a consequence, the two polarizations can be easily separated by choosing a suitable transmission length at a desired operation frequency. The transmission modes, coupling lengths for x- and y-polarizations, as well as the performance of the proposed polarization splitter at a center-frequency of 0.6 THz are investigated and numerically analyzed. A 1.43 cm long splitter with an ultralow loss of 0.4 dB, a high extinction ratio better than -10 dB and a bandwidth of 0.02 THz is achieved.

Novel Knob-integrated fiber Bragg grating sensor with polyvinyl alcohol coating for simultaneous relative humidity and temperature measurement.

A novel high performance optical fiber sensor for simultaneous measurement of relative humidity (RH) and temperature based on our newly designed knob-integrated fiber Bragg grating (FBG) is proposed and experimentally demonstrated. The knob-shaped taper followed by an FBG works as a multifunctional joint that not only excites the cladding modes but also recouples the cladding modes reflected by the FBG back into the leading single mode fiber. Polyvinyl alcohol (PVA) film is plated on the fiber surface by dip-coating technique as a humidity-to-refractive index (RI) transducer, and affects the intensity of reflected cladding modes by way of evanescent fields. By monitoring the intensity and wavelength of the reflected cladding modes, the RH and temperature variance can be determined simultaneously. Experimental results show an RH sensitivity of up to 1.2 dB/%RH within an RH range of 30-95%, which is significantly better than previously reported values. And the temperature sensitivity of 8.2 pm/°Ccould be achieved in the temperature range of 25-60°C. A fast and reversible time response has also been demonstrated, enabling to pick up a humidity change as fast as 630 ms. The capability of simultaneous measurement of RH and temperature, the fast response, the reusability and the simple fabrication process make this structure a highly promising sensor for real-time practical RH monitoring applications.

Microfluidic flowmeter based on micro "hot-wire" sandwiched Fabry-Perot interferometer.

We present a compact microfluidic flowmeter based on Fabry-Perot interferometer (FPI). The FPI was composed by a pair of fiber Bragg grating reflectors and a micro Co(2+)-doped optical fiber cavity, acting as a "hot-wire" sensor. Microfluidic channels made from commercial silica capillaries were integrated with the FPIs on a chip to realize flow-rate sensing system. By utilizing a tunable pump laser with wavelength of 1480 nm, the proposed flowmeter was experimentally demonstrated. The flow rate of the liquid sample is determined by the induced resonance wavelength shift of the FPI. The effect of the pump power, microfluidic channel scale and temperature on the performance of our flowmeter was investigated. The dynamic response was also measured under different flow-rate conditions. The experimental results achieve a sensitivity of 70 pm/(µL/s), a dynamic range up to 1.1 µL/s and response time in the level of seconds, with a spatial resolution ~200 µm. Such good performance renders the sensor a promising supplementary component in microfluidic biochemical sensing system. Furthermore, simulation modal was built up to analyze the heat distribution of the "hot-wire" cavity and optimize the FPI structure as well.

Identification of pyroptosis-related gene signature in nonalcoholic steatohepatitis.

Non-alcoholic fatty liver disease (NAFLD) has emerged as one of the major causes of liver-related morbidity and mortality globally. It ranges from simple steatosis to non-alcoholic steatohepatitis (NASH) characterized by ballooning and hepatic inflammation. In the past few years, pyroptosis has been shown as a type of programmed cell death that triggers inflammation and plays a role in the development of NASH. However, the roles of pyroptosis-related genes (PRGs) in NASH remained unclear. In this study, we studied the expression level of pyroptosis-related genes (PRGs) in NASH and healthy controls, developed a diagnostic model of NASH based on PRGs and explored the pathological mechanisms associated with pyroptosis. We further compared immune status between NASH and healthy controls, analyzed immune status in different subtypes of NASH. We identified altogether twenty PRGs that were differentially expressed between NASH and normal liver tissues. Then, a novel diagnostic model consisting of seven PRGs including CASP3, ELANE, GZMA, CASP4, CASP9, IL6 and TP63 for NASH was constructed with an area under the ROC curve (AUC) of 0.978 (CI 0.965-0.99). Obvious variations in immune status between healthy controls and NASH cases were detected. Subsequently, the consensus clustering method based on differentially expressed PRGs was constructed to divide all NASH cases into two distinct pyroptosis subtypes with different immune and biological characteristics. Pyroptosis-related genes may play an important role in NASH and can provide new insights into the diagnosis and underlying mechanisms of NASH.

Near-Infrared Off-Axis Cavity-Enhanced Optical Frequency Comb Spectroscopy for CO2/CO Dual-Gas Detection Assisted by Machine Learning.

Cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) is widely used as a highly sensitive gas sensing technology in various gas detection fields. For the on-axis coupling incidence scheme, the detection accuracy and stability are seriously affected by the cavity-mode noise, and therefore, stable operation inevitably requires external electronic mode-locking and sweeping devices, substantially increasing system complexity. To address this issue, we propose off-axis cavity-enhanced optical frequency comb spectroscopy from both theoretical and experimental aspects, which is applied to the detection of single- and dual-gas of carbon monoxide (CO) and carbon dioxide (CO2) in the near-infrared. An erbium-doped fiber frequency comb with a repetition frequency of ∼41.709 MHz is coupled into a resonant cavity with a length of ∼360 mm in an off-axis manner, exciting numerous high-order modes to effectively suppress cavity-mode noise. The performance of multiple machine learning models is compared for the inversion of a single/dual gas concentration. A few absorbance spectra are collected to build a sample data set, which is then utilized for model training and learning. The results demonstrate that the Particle Swarm Optimization Support Vector Machine (PSO-SVM) model achieves the highest predictive accuracy for gas concentration and is ultimately applied to the detection system. Based on Allan deviation, the detection limit for CO in single-gas detection can reach 8.247 parts per million by volume (ppmv) by averaging 87 spectra. Meanwhile, for simultaneous CO2/CO measurement with highly overlapping absorbance spectra, the LoD can be reduced to 13.196 and 4.658 ppmv, respectively. The proposed optical gas sensing technique indicates the potential for the development of a field-deployable and intelligent sensor system capable of simultaneous detection of multiple gases.

Coherently parallel fiber-optic distributed acoustic sensing using dual Kerr soliton microcombs.

Fiber-optic distributed acoustic sensing (DAS) has proven to be a revolutionary technology for the detection of seismic and acoustic waves with ultralarge scale and ultrahigh sensitivity, and is widely used in oil/gas industry and intrusion monitoring. Nowadays, the single-frequency laser source in DAS becomes one of the bottlenecks limiting its advance. Here, we report a dual-comb-based coherently parallel DAS concept, enabling linear superposition of sensing signals scaling with the comb-line number to result in unprecedented sensitivity enhancement, straightforward fading suppression, and high-power Brillouin-free transmission that can extend the detection distance considerably. Leveraging 10-line comb pairs, a world-class detection limit of 560 fε/√Hz@1 kHz with 5 m spatial resolution is achieved. Such a combination of dual-comb metrology and DAS technology may open an era of extremely sensitive DAS at the fε/√Hz level, leading to the creation of next-generation distributed geophones and sonars.

Low-loss terahertz waveguide Bragg grating using a two-wire waveguide and a paper grating.

We propose a low-loss terahertz waveguide Bragg grating (TWBG) fabricated using a plasmonic two-wire waveguide and a micromachined paper grating for potential applications in terahertz (THz) communications. Two TWBGs were fabricated with different periods and lengths. Transmission spectra of these TWBGs show 16 dB loss and 14 dB loss in the middle of their respective stop bands at 0.637 and 0.369 THz, with Q factors of 142 and 105, respectively. Insertion loss of 1-4 dB in the whole 0.1-0.7 THz region was also measured. Finally, TWBG modal dispersion relations, modal loss, and field distributions were studied numerically, and low-loss, high-coupling-efficiency operation of TWBGs was confirmed.

Resonant THz sensor for paper quality monitoring using THz fiber Bragg gratings.

We report fabrication of THz fiber Bragg gratings (TFBG) using CO(2) laser inscription on subwavelength step-index polymer fibers. A fiber Bragg grating with 48 periods features a ~4 GHz-wide stop band and ~15 dB transmission loss in the middle of a stop band. The potential of such gratings in the design of resonant sensors for the monitoring of paper quality is demonstrated. Experimental spectral sensitivity of the TFBG-based paper thickness sensor was found to be ~-0.67 GHz/10 µm. A 3D electromagnetic model of a Bragg grating was used to explain experimental findings.

Transcriptome Analysis of Multiple Metabolic Tissues in High-Salt Diet-Fed Mice.

High-salt diet (HSD) is associated with dysregulated metabolism and metabolic disorders. Although previous studies have indicated its effect on metabolic tissues, the involving molecular mechanisms are not quite understood. In the present study, we provided a comprehensive transcriptome analysis on multiple metabolic tissues of HSD-fed mouse model by RNA sequencing. We observed that several genes associated with de novo lipogenesis and cholesterol biosynthesis were significantly downregulated in white adipose tissue and liver tissue of HSD mice group, such as Fasn, Scd1, Acaca, and Thrsp. Furthermore, combined with secretome datasets, our results further demonstrated that HSD could alter expression levels of organokines in metabolic tissues, for example, Tsk and Manf, in liver tissue and, thus, possibly mediate cross-talk between different metabolic tissues. Our study provided new insight about molecular signatures of HSD on multiple metabolic tissues.