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Yuheng Jia1 &ast;, Gaden Luosang2,3 &ast;, Yiming Li,1 Jianyong Wang,2 Pengyu Li,4 Tianyuan Xiong,1 Yijian Li,1 Yanbiao Liao,1 Zhengang Zhao,1 Yong Peng,1 Yuan Feng,1 Weili Jiang,2 Wenjian Li,2 Xinpei Zhang,2 Zhang Yi,2 Mao Chen1 1Department of Cardiology, West China Hospital, Sichuan University, Chengdu, Sichuan, People’s Republic of China; 2Machine Intelligence Laboratory, College of Computer Science, Sichuan University, Chengdu, Sichuan, People’s Republic of China; 3Department of Information Science and Technology, Tibet University, Lhasa City, People’s Republic of China; 4West China Medical School, Sichuan University, Chengdu, Sichuan, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Mao ChenDepartment of Cardiology, West China Hospital, Sichuan University, No. 37 Guoxue Street, Chengdu, 610041, People’s Republic of ChinaTel +86-18980602046Fax +86-28-85423169Email hmaochen@vip.sina.comZhang YiMachine Intelligence Laboratory, College of Computer Science, Sichuan University, Chengdu, 610065, People’s Republic of ChinaTel +86-13882217717Fax +86-28-85466062Email zhangyi@scu.edu.cnPurpose: Late major bleeding is one of the main complications after transcatheter aortic valve replacement (TAVR). We aimed to develop a risk prediction model based on deep learning to predict major or life-threatening bleeding complications (MLBCs) after TAVR.Patients and Methods: This was a retrospective study including TAVR patients from West China Hospital of Sichuan University Transcatheter Aortic Valve Replacement Registry (ChiCTR2000033419) between April 17, 2012 and May 27, 2020. A deep learning-based model named BLeNet was developed with 56 features covering baseline, procedural, and post-procedural characteristics. The model was validated with the bootstrap method and evaluated using Harrell’s concordance index (c-index), receiver operating characteristics (ROC) curve, calibration curve, and Kaplan–Meier estimate. Captum interpretation library was applied to identify feature importance. The BLeNet model was compared with the traditional Cox proportional hazard (Cox-PH) model and the random survival forest model in the metrics mentioned above.Results: The BLeNet model outperformed the Cox-PH and random survival forest models significantly in discrimination [optimism-corrected c-index of BLeNet vs Cox-PH vs random survival forest: 0.81 (95% CI: 0.79– 0.92) vs 0.72 (95% CI: 0.63– 0.77) vs 0.70 (95% CI: 0.61– 0.74)] and calibration (integrated calibration index of BLeNet vs Cox-PH vs random survival forest: 0.007 vs 0.015 vs 0.019). In Kaplan–Meier analysis, BLeNet model had great performance in stratifying high- and low-bleeding risk patients (p < 0.0001).Conclusion: Deep learning is a feasible way to build prediction models concerning TAVR prognosis. A dedicated bleeding risk prediction model was developed for TAVR patients to facilitate well-informed clinical decisions.Keywords: deep learning, transcatheter aortic valve replacement, major or life-threatening bleeding complications, prediction model

Purpose Novel strategies for preventing myocardial ischemia reperfusion injury (MIRI) in a diabetic heart are urgently needed. Resolvin D1 (RvD1) plays important therapeutic roles in inflammatory diseases. However, the therapeutic role of RvD1 in diabetic MIRI is still unknown. Methods Diabetic mice were established with a high-fat diet and streptozotocin (STZ). The mice were pretreated with RvD1 via intraperitoneal injection for 3 days, followed by MIRI. To evaluate the effects of RvD1 on chronic cardiac remodelling, RvD1 was administered for another 2 weeks after MIRI. The effects of RvD1 following MIRI were measured, including the severity of infarct size, regional inflammation, cardiac function, and permeability of cultured endothelial monolayers. Mitochondrial reactive oxygen species (MitoROS) and mitochondrial membrane potential (MMP) were determined using MitoSOX and JC-1. Results RvD1 pretreatment significantly reduced infarct size and the Evans blue content in diabetic injured hearts, which was associated with improved endothelial permeability. At 2 weeks after MIRI, RvD1 treatment partially improved cardiac performance and reduced cardiac fibrosis in diabetic MIRI mice. In vitro, RvD1 attenuated endothelial leakage induced by hypoxia-reoxygenation, H2O2, and lipopolysaccharide (LPS) under high glucose (HG) conditions. Meanwhile, RvD1 remarkably protected endothelial cells from H2O2-induced mitochondrial damage, as evidenced by increased MMP and decreased MitoROS, which was associated with the preservation of VE-cadherin. Conclusion RvD1 alleviates MIRI-induced endothelial permeability and mitochondrial damage injuries in diabetic hearts. Therefore, RvD1 could be a potential therapeutic target for MIRI in diabetes.

The pathological mechanisms underlying cardiac remodelling and cardiac dysfunction caused by pressure overload are poorly understood. Mitochondrial damage and functional dysfunction, including mitochondrial bioenergetic disorder, oxidative stress, and mtDNA damage, contribute to heart injury caused by pressure overload. Mitophagy, an important regulator of mitochondrial homeostasis and function, is triggered by mitochondrial damage and participates in the pathological process of cardiovascular diseases. Recent studies indicate that mitophagy plays a critical role in the pressure overload model, but evidence on the causal relationship between mitophagy abnormality and pressure overload-induced heart injury is inconclusive. This review summarises the mechanism, role, and regulation of mitophagy in the pressure overload model. It also pays special attention to active compounds that may regulate mitophagy in pressure overload, which provide clues for possible clinical applications.

A one-step synthesized LD specific fluorescent probe TTIE with high specificity, good photostability and great capacity in generating cytotoxic reactive oxygen species (ROS) under low powered white light irradiation is designed and synthesized for LD specific image-guided photodynamic therapy (PDT) in human clear cell renal cell carcinoma (ccRCC) primary cells and tissues.

Blood-contacting devices including implantation devices, indwelling medical devices, and extracorporeal circuits have been at risk of thrombus and infections, which lead to treatment failure and serious adverse clinical events. In this study, we have reported a facile and robust mussel-inspired superhydrophilic coating for use on these blood-contacting devices to combat thrombosis and infections. The coating was fabricated mainly based on the rapid formation and accumulation of polydopamine (PDA) nanoparticles and in situ-synthesized using silver nanoparticles (Ag NPs) in the presence of sodium periodate. Therefore, the stability and long-term effects of superhydrophilicity were maintained because of the synergetic contribution of hydrophilic chemical components and surface topography of stacked nanoparticles. Different from mostly reported PDA coatings (with the water contact angle > 30°) that have good affinity to protein adsorption and cause blood coagulation, the superhydrophilic PDA coating in this work effectively reduced the nonspecific adsorption of proteins, maintained the native conformation of the adhered proteins, and further inhibited thrombus formation. Meanwhile, the superhydrophilic surface with Ag+ also demonstrated significant antibacterial properties against both Staphylococcus aureus (Gram-positive bacteria) and Pseudomonas aeruginosa (Gram-negative bacteria). Besides, the embedded Ag+ presented meaningful sustained release with less than 25% released amount even after 30 days incubation, suggesting effective and safe antibacterial ability in a low dose-dependent manner, due to the reduced protein adsorption platform supported killing and releasing of bacteria. Such a superhydrophilic surface-supported low-fouling platform will be proposed as a new strategy for combating thrombotic and infection, especially for blood-contacting devices.

In this paper, a theoretical model of a multimode optical fiber based fluorescence sensor was proposed and established with the aims to optimize specific physical parameters of the sensor including the refractive index of the fluorescent matrix, external diameter and the length of sensing fiber probe which were calculated using the beam propagation method. The plane wave at wavelengths of 395 or 505 nm was used as the excitation light source. The excitation light power in the coating layer was calculated to obtain more excitation fluorescence. The change of fluorescence intensity with structural differences of the parameters was analyzed. The theoretical results showed that for a pure silica fiber using a matrix of higher refractive index (>1.458) material was effective in improving fluorescence performance. The optimized external diameter of the sensing fiber probe was found to be >206 μm with a 200 µm fiber core diameter when the refractive index of the sensing layer is 1.49. Increasing the thickness of the sensing layer increased the level of fluorescence excitation. The fluorescence intensity excited by 395 nm light is stronger than that of light at 505 nm.

Most recent studies have proposed the paradoxical benefits of obesity in surgical populations. For patients who underwent transcatheter aortic valve implantation (TAVI) for aortic stenosis, the prognostic roles of obesity and high body mass index remain controversial. Therefore, the objective of this meta-analysis was to evaluate whether the 'obesity paradox' exists in patients undergoing TAVI. We searched in PubMed and EMBASE to identify the eligible articles. Odds ratios and hazard ratios with the corresponding 95% confidence intervals (CI) were adopted for synthesizing short-term and long-term survival outcomes, respectively. The level of heterogeneity and the publication bias between studies were also estimated. Finally, there were 16 studies with 12 330 patients who met the eligibility criteria and who were thus included in this review. When body mass index was analysed as a continuous variable, each increase of 1 kg/m2 was significantly associated with the lower 30-day mortality rate (odds ratio = 0.95; 95% CI = 0.93-0.97; P < 0.001) and better long-term overall survival (hazard ratio = 0.96; 95% CI = 0.94-0.97; P < 0.001) for patients undergoing TAVI. The obese patients had a significantly lower risk of 30-day mortality after TAVI than did normal patients (odds ratio = 0.69; 95% CI = 0.50-0.95; P = 0.024). Further analyses indicated that the obesity could be predictive of more favourable long-term overall survival of TAVI (hazard ratio = 0.84; 95% CI = 0.72-0.97; P = 0.021). However, we found no difference in procedural complications between the obese and normal patients. In conclusion, higher body mass index and obesity seem to have protective benefits on both short-term and long-term survival of TAVI patients. Current evidence suggests that the 'obesity paradox' may really exist in TAVI.

In this paper, a new optical fiber process tomography (OFPT) configuration for the measurement of two-phase flows in the space of cylindrical pipes with circular cross-sections in industry is developed. Rotate scanning is used to acquire enough projections. A liquid drop or gas bubble can be regarded as an opaque medium owing to the employment of small numerical-aperture (N.A.) optical-fiber-collimators (OFC) in future practical systems. Theoretical calculation indicates that an extremely high resolution, e.g., 1/(40,000π) can be realized by decreasing the size of a pixel to the width of a light ray, e.g., 1 mm when the velocity of the flow is 10 cm/s if data acquisition rate of single channel and the rotation speed are 2 Mbps and 1500 rpm/min, respectively, which can be realized by commercial high-speed data acquisition card and single-shaft turntable.

A novel positioning error reduction technique is proposed for dual Mach-Zehnder fiber interferometric distributed vibration sensor. The 3 dB bandwidth of the power spectrum of interference signal is broadened to reduce the mean square error (MSE) of the cross-correlation based positioning algorithm. A high-pass filter (HPF) whose cutoff frequency is larger than the upper frequency of signal 3 dB bandwidth is applied to reshape the original power spectrum by attenuating the magnitude of low-frequency mainlobe to the same order as that of the small high-frequency components. The usage of HPF can cause bandwidth broadening and signal to noise ratio (SNR) reduction, the influence of both effects on ultimate positioning MSE are analyzed in detail. Theoretical analysis shows that there exists a valid region for the cutoff frequency of the HPF within which the contribution of bandwidth broadening dominates the process. The technique is also experimentally verified and analyzed by field test on an installed submarine cable between two islands of Zhejiang Province, China. Field test results coincide with the theoretical predictions and show that a maximum of 7 dB reduction of positioning MSE can be achieved when optimal cutoff frequency of HPF is used.

The positioning mean square error (MSE) prediction theory for dual Mach-Zehnder interferometric vibration sensor is proposed. The cross-correlation algorithm is considered. By taking into account the general noise time delay model, the impact of each noise term in output interference signal to ultimate positioning MSE is to our knowledge the first time be analyzed. An equivalent signal to noise ratio term for general noise time delay model is derived. It shows that incoherent phase noise (coming from polarization fading effect) makes an equivalent contribution to positioning MSE as additive noise under assumptions. In practical prediction, cross-correlation coefficient between two channel signals can be used to estimate positioning MSE. Simulation as well as experimental results are presented to corroborate the theory.

In this paper, we analyze and optimize the PGC demodulation algorithm for optical interferometers in order to extend its usage in low-cost all digital schemes. In our low-cost system, we choose heterodyne interferometer and direct modulation on Distributed FeedBack (DFB) laser and optimize the algorithm, as well as some of the system parameters in order to have the best linearity and noise performance. We first analyze the influence of low-pass filters (LPF) in the PGC-DCM algorithm. A detailed theoretical model of LPF is deduced and reveals that a nonideal LPF is the major limit of linearity in digital systems. Experimental results show that the PGC-atan algorithm will have a 40-dB higher linearity than PGC-DCM one with a 60-order digital FIR filter. Then we analyze the influence of the intensity modulation in PGC-atan algorithm, the main source of the nonlinearity in PGC-atan algorithm, and propose a simple but effective modification. Experiment results verified that it can reduce the influence of intensity modulation by about 20 dB. Further, the impact of Light Intensity Noise (LIN) and circuit noise on the output noise level is analyzed. Equations are derived to calculate the Power Spectrum (PS) of output noise caused by LIN or circuit noise. Simulations show that the theoretical analysis is of high accuracy-less than 0.5 dB. With these equations, a new parameter-Noise Transfer Factor-is defined for better discription of the noise performance of PGC. The results show that the modulation depth C and the DC work point Phi = mean(phi(t)) have great impact on the output noise level. By changing C and Phi , the output noise may decrease as much as about 20 dB. Then three examples show how to choose the system parameter according to the characteristics of LIN or circuit noise. As well, the noise performance of PGC-DCM is analyzed. The result reveals a turning point at the output noise base, which worsens its noise performance at lower frequency. PGC-DCM has the same NTF at frequency higher than the turning frequency. A parameter Frequency Conversion Coefficient is introduce to calculate the turning point.

In this work, a optical-fiber air-backed mandrel hydrophone is proposed and investigated both analytically and experimentally. The two-dimensional and three-dimensional quasistatically theoretical models of the hydrophone is created and compared, and the phase sensitivity of the hydrophone is analyzed. The theoretical result of phase sensitivity with three-dimensional model is −153.3 dB re rad/μPa. Twenty-two hydrophones of this type according to the model presented are constructed and tested. The experiment results show that experimental results of mean values of phase sensitivity are about −153 ± 0.5 dB re rad/μPa and have the close agreement with the estimation of theoretical models. The size of the fiber sensor is ∅12 × 55 mm, the normal phase sensitivity achieves −308 dB re 1 μPa −1 , the 3 dB effective bandwidth of the frequency response is 30 kHz, and the responsivity decreases less than 0.5 dB when static pressure is 2 MPa (200 m water depth). The hydrophone is easy to constructed at low cost with simple structure, and some new type of it with the required performances could be designed according to the model presented.

Cross-sensitivity is an important parameter of an accelerometer because it directly affects the sensor's vector performance, which is paid more and more attention to. In this paper, a suite of analytical models for researching the cross-sensitivity performance of fiber-optic accelerometer is developed. The theoretical and experimental research was carried out to demonstrate the relation of the performance of a fiber-optic accelerometer based on compliant cylinder and elastic properties of the cylinders. Three kinds of silicone rubber cylinders with different Young's modulus were examined. By analyzing the cross-sensitivity models of the sensor, some characteristics of cross-sensitivity performance are revealed and discussed. Those models are useful for the design of accelerometers of such type.

A long period grating (LPG) coated with hydrogel has been developed for monitoring the relative humidity (RH) levels. The response wavelength of the LPG varies with the changes of the relative humidity. The four-layered step index waveguide model is presented to explain this observation, which is based on the effect of the hydrogel thin film, the index of which increases with the increasing RH. Experiment shows that the hydrogel-coated LPG sensor is highly sensitive between 38.9% and 100% RH, and behaves linearly with humidity with an accuracy of ±2.3% RH. The small-size and low-cost LPG fibre sensor will have extensive applications in various areas, such as remotely measuring RH, building health monitoring, medical facilities and goods' preservation.

The feasibility of an optical fibre corrosion sensor (OFCS) was studied. A multi-mode fibre was metallised by physical vacuum deposition and electroplating of a Fe–C alloy film on a 1–2 cm uncladded section of an optical fibre. The shift of light power transmitted through the fibre was registered with corrosion. Microanalysis was carried out to show the formation of metallised film. The electrochemical process of the corrosion on the fibre was researched by continuously monitoring open potential Ecorr, linear polarized resistance Rp and electrochemical impedance spectra.

Electrical capacitance tomography (ECT) has been used to obtain the cross-section images of processes with different dielectric materials inside. Image reconstruction with ECT is to retrieve the permittivity distribution of materials inside the sensor from the capacitance measurements. Algorithms for ECT image reconstruction should be both precise and fast in order to satisfy the requirements of real-time monitoring of the dynamic behavior of processes. Several algorithms have been developed for ECT image reconstruction. The Landweber iteration is the most precise one. However, the low convergence rate of the Landweber iteration limits its application for on-line imaging. This paper introduces an iterative algorithm based on the Landweber method with preconditioning for ECT image reconstruction. A preconditioner, which is equivalent to a filter, is applied to the Landweber iteration. The convergence of this algorithm is analyzed. Its performance is evaluated by using simulated and experimental data corresponding to certain typical permittivity distributions. Preliminary numerical and experimental results show that this algorithm converges more rapidly than the Landweber iteration without preconditioning. Therefore, image reconstruction iteration can be accelerated, which makes on-line quantitative image reconstruction possible.

In this paper, a novel optical fiber process tomography (OFPT) probe is developed; in which, eight optical fiber sensor units are uniformly distributed around the cylindrical container. Each unit comprises three optical fiber collimators, one photo detector and one optical window. The window is specially designed to make the light pass through and the container waterproof. All devices in the probe are simply and easily collimated owing to the exact calculation and precision manufactory. The genetic algorithms (GAs) are used. The experimental results show that the novel OFPT system can measure gas–solid two-component distributions.

In this paper, a novel space structure and its mathematic analysis for optical fibre process tomography is presented which can be used to measure medium distributions and contents in a circular cross section of cylindrical space in the field of industry process monitoring and control. The structure comprises a centre-supporting pole and many extensible arms; an electrical motor is placed in the pole to control all arms stretching and retracting simultaneously. At the end of each arm a reflecting prism is employed to realize the transformation of the rays in the arm and the measured plane. Fibre cable and photoelectrical devices can be sealed in the arms or pole specially designed to withstand conditions such as high temperature and high pressure. A detailed analysis of all kinds of positioning accuracies indicates that it is feasible and practical to use the novel structure in engineering.

A differential fiber Bragg grating (FBG) sensor with a free active element bulk-modulus for high-pressure (or displacement) measurement is presented. Based on the differential measurement method and an isosceles triangle cantilever structure, problems of cross-sensitivity and chirped signal in FBG sensor are improved both theoretically and experimentally. Preliminary experiments indicate that temperature-compensated measurement results agree well with the theoretical analysis. Displacement measurement sensitivity is ∼1.75 pm / μm , and the estimated pressure measurement resolution can reach 0.27 MPa in case the wavelength shift measurement resolution is 0.01 nm .

Wavelength modulation spectroscopy by the use of a tunable optical filter was applied to an intra-cavity fiber laser gas sensor. The optimum pump power and the modulation amplitude that maximized the signal-to-noise ratio were found. A minimum detectable gas (C/sub 2/H/sub 2/) concentration of 1000 ppm was experimentally achieved.

Fiber Bragg grating (FBG) sensors are one of the most exciting developments in the fields of fiber-optic sensors in recent years. One of the problems in using grating sensors is the discrimination of temperature and strain responses (cross-sensitivity effect between temperature and strain), because in most real-world applications both of these quantities will be acting on the sensor elements. Another problem is how to measure a small Bragg wavelength shift accurately. This article presents a comprehensive and systematic overview of discrimination measurement methods and demodulation techniques for FBG sensors. It is anticipated that FBG sensors will be commercialized and widely applied in practice in the near future due to the maturity of economical production of FBGs and the availability of cost effective measurement and demodulation techniques. Recent research work about a differential FBG sensor for simultaneous measurement of down-hole high pressure and temperature and the corresponding demodulation techniques are also introduced in this paper.

Genetic algorithm is used to improve the performance of FBG sensors within in a wavelength-division multiplexed sensor network. Simulations and experiments demonstrated wavelength detection accuracy of a few microstrains even when the spectrums of FBGs within the network are partially or completely overlapped.

This paper describes an optical-fiber sensor developed for temperature measurement under offshore oil well conditions. The sensor exploits the displacement of the optical absorption edge occurring in semiconductors under the influence of temperature variation as a result of temperature-induced energy shifting of conduction band extrema. The structure of the sensor and the measurement principle are described. The common-path reference measurement and node type error compensation technologies are developed. And, the detailed theoretical analysis indicates that the proposed sensor system can effectively improve measurement errors caused by light fluctuation, difference and variation of the detector responsiveness, circuit magnification times, and so on. It proves that this sensor system can be applied under long-term formidable conditions with fairly good measurement stability.

The refractive index of salt water will change because of the variation of salinity, and the developed experimental setup exploits beam deviation caused by refraction due to the salinity of measured water at the receiving end face of a measurement cell. Based on a differential refractometer, a reference water cell filled with distilled water is partitioned by an oblique optical-transmission plate from a horizontal rectangular water tank, which, as a measurement element, is filled with measured salt water. Beam deviation caused by salinity change is detected by a position-sensitive detector (PSD). Experimental results indicate the feasibility of the developed system with a measurement resolution of 0.012‰ and repeatability error better than ±0.3‰. Errors which will affect the measurement performance are discussed and analyzed in detail.

A novel optical fiber sensor used for remote monitoring of salinity in water is proposed. Based on the detection of beam deviation due to the refractive index changes of the salt water, salinity can be measured by a position-sensitive detector. The measurement principle is theoretically described. Preliminary prototype is set up, and experimental results indicate the feasibility of the method. Salinity measurement resolution can reach 0.012%o within the measurement range from distilled water to salt water with salinity of 50%o.

In this paper, we put forward novel theories and their empirical formulae for pixel distribution and plane-light-path design in optical fibre process tomography (OFPT), by which the novel OFPT structure parameters can be easily calculated according to the engineering requirements. The designed OFPT system can be used in the circular cross-section of cylindrical space in industry process monitoring and control to measure the medium distribution and contents, such as measurements for two-phase flows.

We propose a semiconductor absorption optical fiber temperature sensor adapted to offshore explorations. The sensing mechanism relies on the well-known temperature induced shift of the optical absorption edge of GaAs. The sensor system uses a common-path reference measurement method combined with a node-type error compensation technology. This allows to correct for errors caused by fluctuations of the light intensity level, by differences in and variations of the detector responsiveness and by the amplification of the processing circuitry. Preliminary experimental results show the feasibility of our approach and indicate that we can achieve a temperature measurement uncertainty of ±0.2 °C.

The paper describes experiments concerning distance measurement with fiber-optic sensor and improvement of the measurement principle. The sensor probe was well-designed with a small structure and multi-function. The novel optical fiber probe arrangement as well as the possibilities of use for complex measurement problems are explained using the measurement of an internal screw thread as an example. The experimental results show that the measurement uncertainty of the thread minor diameter can reach ±10 μm, and the stability of the measurement system is better than 0.07%.

In this paper, we develop novel pixel distribution and plane-light-path structures for optical fibre process tomography, which can be used to measure medium distributions and contents in a circular cross section of cylindrical space in the field of industry process monitoring and control. Such structures partition the circular region into two parts: one is a ring-measured part including 60 pixels; the other is a centre unmeasured part corresponding to a mechanical supporting pole. Eight optical fibre sensor units are uniformly distributed around the circle, each consisting of six transmission fibres. A simple numerical model of stratified two-phase flow is employed to provide the projected data for image reconstruction and verify the feasibility of the novel structures. Reconstructed images are obtained in the presence of an algebraic iterative reconstruction algorithm, and they are basically in accordance with the original models. Theoretical image-reconstructed relative resolution, taking into account the 60 pixels, is 1.67%. However, we found that the reconstructed error is less than 5%.

The paper describes a new optic fiber sensor developed for simultaneous seawater temperature and salinity measurement. Temperature-dependent semiconductor absorption at the band edge is used as the principle of the temperature measurement, and the sensor exploits beam deviation caused by refraction due to the salinity of seawater at the receiving end face of the optical fiber array. The measured optical signals are reflected and transmitted through a sequentially linear arranged fibers array, and then the light intensity peak value and its deviant are detected by a charge-coupled device (CCD). The sensor probe is composed of an intrinsically pure GaAs single crystal, a right angle prism, a partitioned water cell, the emitting fiber with an attached self-focused lens and the linear arranged receiving fibers array. Theoretical analysis and simulations verify the feasibility of the proposed system.

A fluorescence fiber sensor based on step-index multimode optical fibers is simulated and design by beam propagation method with Beamprop module of Rsoft-CAD software, in the requirement of the much more exciting light in fluorescent material coated on the fiber core. The normalized exciting light power in the coating layer is calculated and analyzed. According to the numerical optimal results, the refractive index n o of fluorescent material layer is 1.49, and the optimal external diameter of coated layer should be greater than 206µm.

The aim of the current study is to investigate the effect of visfatin on cardiomyocyte hypertrophy. Cultured H9c2 cardiomyocytes were exposed to visfatin at different concentrations for different periods of time, and the markers of cardiomyocyte hypertrophy were detected. Moreover, pravastatin, the inhibitor of endoplasmic reticulum stress (ERS) or thapsigargin, an ERS agonist was used respectively to pre-treat the cells before visfatin stimulation. F-actin staining was performed to measure the cell surface change. The mRNA expressions of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and ERS markers including glucose-regulated protein 78(GRP78), C/EPB homologous protein (CHOP) and activating transcription factor 6 (ATF6) were assessed by real time RT-PCR. The change of protein level of GRP78 and CHOP was detected by Western blot. The experimental data demonstrated that exposure to 100 or 150 ng/mL concentrations of visfatin for 24 h, or 100 ng/mL of visfatin for 24 or 48 h, significantly increased the expression of markers for cardiomyocyte hypertrophy. Visfatin stimulation provoked ERS in H9c2 cells. Furthermore, pre-treatment with pravastatin partially inhibited the visfatin-induced mRNA expression of ANP and BNP in H9c2 cells, whereas thapsigargin promoted the visfatin-induced expression of cardiomyocyte hypertrophy markers. The results suggest that visfatin might induce cardiomyocyte hypertrophy via ERS -dependent pathways.

The parameters of the semiconductor laser source are vital for the performances of optical coherent systems. In this paper, a novel method to measure the phase-shift φm between laser central optical-frequency modulation (COFM) and the accompanied optical-intensity modulation (AOIM) is proposed, which is easy to realize and requires no further fiber etalons or high-speed demodulators. An orthogonal test is utilized to measure φm. Experimental results show that the value of φm approaches 1.09π under different COFM conditions. Then the interference model of phase-generated carrier (PGC) demodulation is modified by taking into account the effect of φm, and the influences of φm on the demodulation results using two methods (look-up table and AOIM-factor division) are further analyzed in detail.

A Mach-Zehnder interferometer based on cascaded long-period gratings with a hydrogel thin-film coating is developed for monitoring the relative humidity (RH). The visibility of fringes and phase shift of the fringes are measured using Fourier analysis. The sensors show good linearity using the visibility of fringes from 60%RH to 100%RH with the ability to measure below 60% at reduced accuracy using the phase shift. An RH accuracy of 0.4% is achieved.

The long-period grating (LPG) coated with the hydrogel was investigated for monitoring the relative humidity (RH) levels-the ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature. The experimental results showed that the resonant wavelength of the hydrogel-coated LPG was shifted when the RH varied from 38.9% to 100%, with a linearity of 99.5% and an accuracy of plusmn2.3% RH

A novel digital demodulation scheme for an interferometric optical fiber sensor is developed, which uses only an interferometer with zero optical path difference, and has a larger dynamic range and a faster operation speed than that of a digital phase generated carrier scheme

A novel method for simultaneous measurement of current and voltage employing a single monomode low-birefringence (Lo-Bi) fiber is described. This uses the Faraday effect for detection of current and the Kerr effect for detection of voltage. The waveform of the output light intensity due to the Kerr effect has been detected and the Kerr constant was measured as 5.4×10−16 m/V−2 at 25°C. Theoretical analysis shows that the current component can be measured free from the influence of the voltage component and the two components can be easily separated.

The phenomenon of the interference pattern splitting in an all-fiber white-light interferometer is investigated. It is found that the interference pattern will change its amplitude and shape as the fiber which forms the optical path is subjected to tension, bending, or torsion. This leads to the interference pattern fading and deteriorates the zero-order fringe identification. An explanation based on the stress-induced birefringence is presented with numerical simulation results. It is shown that the periodic change in the amplitude and shape results from the periodically changed phase difference between the two orthogonal LP 01 modes in the presence of external loads.

Fiber inhomogeneity induced random birefringence in single mode fiber (SMF) can lead to the polarization fading effect in distributed fiber vibration sensor using Mach-Zehnder interferometry. By considering the contributions of both visibility and phase noises in interference output signal, the influence of polarization fading effect on the position accuracy of distributed vibration sensor using cross-correlation algorithm is theoretically derived. A new term of equivalent signal to noise ratio (SNRe) is defined in the model. Based on the theory, a novel method for decreasing the positioning error of low-frequency vibration signal is given and verified by field test results.

A novel all-metal fiber-optic accelerometer with Michelson interferometric configuration is proposed, using mass blocks and flexible reed structure. The sensing arm is configured to directly transform the applied acceleration to fiber deformation in axial direction, which increases the acceleration sensitivity of the sensor. The axis of the reference arm is set orthogonal to that of the sensing arm in order to make it insensitive to applied acceleration, and thus decrease the phase noise of the sensor. Using the flexible reed of 1mm thick and the mass block of 208g, an acceleration sensitivity of 556.7rad/g(54.9dB) is achieved by this structure. In the case of 10 -4 rad/rt Hz(100Hz)noise floor, the minimum detectable acceleration is 200ng/rt Hz.