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Liver fibrosis occurs in response to any etiology of chronic liver injury. Lack of appropriate clinical intervention will lead to liver cirrhosis or hepatocellular carcinoma (HCC), seriously affecting the quality of life of patients, but the current clinical treatments of liver fibrosis have not been developed yet. Recent studies have shown that hypoxia is a key factor promoting the progression of liver fibrosis. Hypoxia can cause liver fibrosis. Liver fibrosis can, in turn, profoundly further deepen the degree of hypoxia. Therefore, exploring the role of hypoxia in liver fibrosis will help to further understand the process of liver fibrosis, and provide the theoretical basis for its diagnosis and treatment, which is of great significance to avoid further deterioration of liver diseases and protect the life and health of patients. This review highlights the recent advances in cellular and molecular mechanisms of hypoxia in developments of liver fibrosis.

With the wide application of information technology represented by computer and Internet, as well as the rapid development of cloud computing, big data, artificial intelligence and other new technologies, the society has higher and higher requirements for people's information literacy, which also profoundly changes the talent demand and education form. Under the background of the promulgation of "education informatization 2.0 action plan" and the development of new information technology, it is urgent for higher vocational colleges to build a set of students' information literacy evaluation system to adapt to the development of information society. This paper combs the information literacy evaluation system and characteristics at home and abroad, points out the necessity of constructing the information literacy evaluation system of Higher Vocational Students under the background of education informatization 2.0, and analyzes the content of the information literacy evaluation system.

This study aimed to investigate the application of the healthcare failure mode and effect analysis (HFMEA) to reduce the incidence of posture syndrome of thyroid surgery (PSTS). Subjects before (n = 78, July 2017–December 2017) and after (n = 114, January 2018–June 2018) HFMEA implementation (The Second Hospital of Nanjing, Nanjing University of Chinese Medicine) were selected. The training for PSTS was optimized using HFMEA. The occurrence of PSTS was reduced from 59% to 18% after HFMEA (P

Using a first-principles method based on density functional theory, together with the generalised gradient approximation, the structures and electronic properties of Cn(n = 2–9) clusters have been determined, and their highest occupied molecular orbital–lowest unoccupied molecular orbital energy gaps and their binding energies have been calculated. The results show that the Cn cluster binding energy, and therefore, the stability of the cluster structure increase monotonically with cluster size n. The cluster energy gap varies in a non-monotonic manner with cluster size, and its range of values indicates that the clusters behave as semiconductors. According to the partial density of states of the carbon atoms, the energy of the s state falls with increasing cluster size, whereas the energy of the p state rises.

Despite great advances in lipid-lowering therapy, the gender-based disparities in lipid goal success among Chinese coronary heart disease (CHD) patients receiving lipid-lowering treatment remained uncharacterized. Furthermore, little is known about potential causes for this gender imbalance. This cross-sectional trial included 25 697 patients treated with lipid-lowering agents from 122 centres between April 2012 and October 2012; data for 9420 participants with CHD were analysed in the present study; all underwent clinical examination and had their latest fasting lipid profiles while on lipid-lowering therapy recorded. Logistic regression was used to explore possible factors associated with gender disparity in goal attainment rates, and to what extent each factor contributes. Of 9420 CHD patients (42.5% women) evaluated, women had a significantly lower overall low-density lipoprotein cholesterol (LDL-C) success rate than men (46.2 vs. 62.7%, P < 0.0001). Among CHD patients with diabetes, only 31.5% of women and 46.4% of men ( P < 0.0001) attained the optional LDL-C target of

The authors deliver a complete overview of fiber-optic Fabry-Perot (FFP) sensing technology, integrating the knowledge and tools of multiple fields including optics, sensing, micromachining, instrumentation, physics, and materials science. The main chapters discuss operating principles, microstructures, fabrication methods, signal demodulation, and instrumentation. This treatment spans the full range of structures (intrinsic/extrinsic, multimode fiber vs single-mode fibers), as well as advanced micromachining technologies and major interrogating and multiplexing methods for the formation of multi-point, quasi-distributed sensing networks. Readers will also gain a summary of state-of-the-art applications in oil, gas, and electricity industries, aerospace technology, and biomedicine. Yun-Jiang Rao is Dean of the School of Communication & Information Engineering, and Director of the Key Lab of Optical Fiber Sensing & Communications at the University of Electronic Science and Technology of China. Zeng-Ling Ran and Yuan Gong are both associate professors at the Optical Fiber Technology Research Laboratory of the University of Electronic Science and Technology of China.

Recent progress in using excimer and femtosecond lasers to fabricate functional fiber-optic sensing devices is reviewed extensively in this paper. The application of femtosecond lasers is to fabricate fiber gratings and in-line fiber-optic interferometers for measurements of strain, temperature and refractive index. The application of 157 nm excimer lasers is to create fiber gratings and in-line fiber interferometers for measurements of strain, acceleration, pressure, temperature and refractive index. Compared with conventional optical fiber sensors, these novel micro optical fiber sensors fabricated by laser-micromachining have outstanding advantages, such as fast and direct formation, easy mass-production with ultralow-cost, good reproducibility, excellent optical performance, low temperature cross-sensitivity, etc., which pave a way to form a new generation of miniature fiber-optic sensors for many applications.

An inline fiber-optic micro-Fabry-Perot (MFP) cavity and a short fiber Bragg grating (SFBG) is overlapped to form an integrated MFP/SFBG sensor for simultaneous measurement of temperature and strain under high temperature (300 °C). The FP cavity is fabricated on a GeO 2 -doped photon sensitive fiber using the 157-nm laser micromachining technique and the SFBG is written at the same position of the MFP cavity using the standard 248-nm laser method. As the MFP cavity and SFBG have different sensitivity coefficients to temperature and strain, they can be utilized for realization of simultaneous measurement of dual parameters.

The Raman amplification can be employed to obtain the enhanced sensing performance in long-distance Brillouin optical time-domain analyzer (BOTDA) with higher temperature measurement accuracy over the whole sensing fiber. Theoretical investigation on the detected probe waveshape has been performed by using the probe-pump coupled equations combined with Raman amplification. The experimental characterization has been demonstrated to validate the theoretical prediction. The results show that, the 75 Km sensing distance can be achieved by utilizing the bi-directional Raman amplification with measurement accuracy of ±0.6°C over the whole sensing fiber. The larger Raman power and Brillouin pump power are helpful to improve the sensing signal-noise ratio (SNR). There exists an optimum range for the input probe power and the extinction ratio (ER) of input Brillouin pump pulse. The BOTDA with Raman amplification has considerable potentials to realize long- distance strain and temperature measurement for structural health monitoring and fire alarming, etc.

A Mach-Zehnder (M-Z) interferometer formed by two cascaded long-period fiber gratings (LPFGs) serving as ‘many’ multi-channel edge filters is used to detect the wavelength shift, induced by measurand of fiber Bragg grating (FBG) sensors with high optical SNR of >60 dB due to the use of a fiber ring laser, for the first time to our knowledge. Advantages of such a demodulation device are low-cost, compact, easy fabrication and implementation, good immunity of vibration and temperature, etc. In addition, in order to improve the resolution for dynamic strain measurement, a spectral analyzing algorithm called Music modern spectrum estimation is adapted. The experimental results show that a dynamic strain resolution of 0.1 μɛ/Hz 1/2 at 700 Hz is obtained, which is 10 times improvement in strain resolution when compared with conventional FFT method.

A novel bend-insensitive long-period fiber grating (LPFG) sensor written using focused CO 2 laser pulses is demonstrated, for the first time, to our knowledge. It is found that the central wavelength shift of such a LPFG is only −0.018 nm even for a curvature of 1.1 m −1 at the most bend-insensitive position of the LPFG. Experimental results show that the bend sensitivity of the central wavelength of the LPFG has a periodic distribution along its circular directions. Such a bend-insensitive sensor could be used to solve the problem of cross-sensitivity between bend and other measurands, such as temperature, strain or refractive index, which is an unsolved problem for LPFG sensors in practice. In addition, the bend sensitivity of the LPFG can be adjusted by selecting its circular positions.

In this paper, we report novel long-period fiber gratings (LPFGs) fabricated by using a new writing technique that is mainly based on the thermal shock effect of focused high-frequency CO2 laser pulses at several kHz. Several unique characteristics of these LPFGs, such as bend and transverse-load, etc., are observed by experiments, for the first time, to our knowledge. These unique features of the LPFGs are mainly due to the asymmetrical distribution of the refractive index on the cross-section of the LPFG induced by high-frequency CO2 laser pulses. Based on these novel LPFGs, an amplified spontaneous emission noise filter and a gain equalizer have been demonstrated for the noise figure reduction and the gain spectrum flattening of Er-doped fiber amplifiers (EDFAs), respectively. By means of the unique bending and loading features of the LPFG, two tunable gain equalizers have been demonstrated for dynamic gain flattening of EDFAs.

In this paper, we report a novel long-period fiber grating (LPFG) fabricated by using a new writing technique that is mainly based on the thermal shock effect of focused high-frequency CO/sub 2/ laser pulses at several kilohertz. A number of unique characteristics of such a LPFG, such as bend, torsion, and transverse load, are observed by experiments, for the first time, to our knowledge. Based on these unique features, a novel bend-insensitive LPFG sensor that could solve the problem of cross-sensitivity between bend and other measurands, a novel torsion sensor that can realize absolute measurement of twist rate, and a load sensor that can achieve simultaneous measurement of transverse load and temperature using a single LPFG element are proposed and demonstrated. These unique features of the LPFGs are mainly due to the asymmetrical distribution of the refractive index on the cross section of the LPFG induced by high-frequency CO/sub 2/ laser pulses.

A single long-period fibre grating (LPFG) element written by focused high-frequency CO2 laser pulses is demonstrated for simultaneous measurement of transverse load and temperature. Temperature and transverse load can be directly measured by detecting the resonant wavelength shift and the resonant peak amplitude change of the LPFG, respectively, as there are two special circular orientations along the fibre axis where the resonant peak amplitude change of the LPFG has a linear relationship with the load applied and is insensitive to the resonant wavelength shift. Such a sensor could solve the cross-sensitivity problem between transverse load and temperature due to the unique feature of this type of LPFG, i.e. the wavelength-load-sensitivity of the LPFG strongly depends on loading orientations due to the non-uniform distribution of the refractive index on the cross-section of the LPFG caused by the thermal shock effect and other effects of the high-frequency CO2 laser pulses exposure method used.

The combination of Raman amplification and optical pulse coding (OPC) is proposed to reduce the frequency uncertainty in a long-distance Brillouin optical time-domain analyzer (BOTDA) under higher spatial resolution. The experimental characterization of temperature sensing with measurement accuracy ~ 1°C under ~ 2.5-m spatial resolution over a whole length of sensing fiber is demonstrated. The sensing fiber is composed of 49.6-km fiber at 10.8-GHz Brillouin frequency shift (BFS) and 25-km fiber at 11.005 GHz.

A novel tunable gain equalizer based on the long-period fiber grating (LPFG) induced by high-frequency CO/sub 2/ laser pulses is demonstrated, for the first time, to our knowledge. Both the resonant wavelength and the resonant peak amplitude of the novel LPFG have a good linearity with temperature and transverse load, respectively. The wavelength and the peak amplitude of the gain equalizer can be tuned by the means of adjusting temperature and transverse load independently, showing that this tunable equalizer is a practical approach to realizing dynamic gain equalization in erbium-doped fiber amplifier systems.

An all-fibre dynamic gain equalizer based on a novel long-period fibre grating (LPFG) written on a photosensitive fibre by high-frequency CO2 laser pulses is demonstrated for the dynamic gain flattening of Er-doped fibre amplifiers. The resonant peak amplitude of such a dynamic gain equalizer can be adjusted linearly by bending the LPFG. The gain profile of the Er-doped fibre amplifier constructed has been flattened to within ±0.7 dB over a 32 nm bandwidth using such a device.

The combination of Raman amplification and optical pulse coding (OPC) is proposed to reduce the frequency uncertainty in long-distance BOTDA under higher spatial resolution. The experimental characterization of 74.6Km temperature sensing with measurement accuracy ~1oC under ~2.5m spatial resolution over the whole length of sensing fiber is demonstrated. The performance comparisons of BOTDA with purely Raman amplification and combined Raman amplification with OPC are also displayed.

A novel tunable fiber ring laser configuration with combination of hybrid Raman amplification and erbium-doped fiber amplification (EDFA) is proposed for realizing ultra-long distance (300km) fiber Bragg grating (FBG) sensor system. The experimental results show that a 300 km transmission distance is achieved with an optical SNR of 4 dB, which is the longest FBG sensing distance, to the best of our knowledge.

A novel fiber-optic phase-sensitive optical time-domain reflectometer (Φ-OTDR) distributed sensing system is proposed and demonstrated for long-distance intrusion monitoring. By using the bi-directional Raman optical amplification technology, even intrusion signal detection along the whole sensing distance of ~62km has been demonstrated, resulting in the longest and the most sensitive Φ -OTDR distributed sensing system reported so far, to the best of our knowledge. In addition, high-power single-mode fiber laser with ultra-narrow line-width and special optical fiber cable encapsulated by fiber reinforced plastic (FRP) are used to further enhance the intrusion detection sensitivity, respectively.

An in-fiber Bragg grating (FBG) dynamic strain sensing system based on a fiber ring laser configuration and the Eigenvector spectrum analysis method, is proposed and demonstrated. An ultrahigh dynamic strain resolution of 5x10 -5 ne /Hz 1/2 is achieved due to both the use of the supper white-noise suppression ability of the advanced spectrum analysis method and the high optical signal-to-noise ratio (SNR) (~65dB) of the sensing signal generated by the fiber ring laser scheme. This is the highest dynamic strain resolution achieved so far for a single FBG sensor at frequency of

We demonstrate experimentally the light coupling effects between two parallel CO(2)-laser written long-period fiber gratings. For gratings written in standard single-mode fibers, the coupling efficiency depends strongly on the fiber orientation with the strongest coupling obtained when the exposed sides of the fibers face each other, while for gratings written in boron-doped fibers, the coupling efficiency is independent of the fiber orientation. We achieve a peak coupling efficiency of approximately 86% with gratings written in boron-doped fibers by using a suitable surrounding refractive index and offset distance between the two gratings. Our results suggest the possibility of realizing efficient broadband all-fiber couplers with CO(2)-laser written long-period fiber gratings.

To solve the problem of function failure of space-borne spread spectrum transponder caused by single event upsets(SEUs), the anti-SEU design of signal processing machine of space-borne spread spectrum transponder is studied in this paper. The design adopts SRAM-based FPGAs, DSP and anti-fuse FPGA to achieve SEU hardening signal processing machine. The transponder using the method can avoid failure caused by SEUs.

A novel tunable fiber ring laser configuration with multi-stage hybrid Raman/EDF amplification is first proposed and demonstrated for realizing an ultra-long-distance (~100 km) fiber Bragg grating (FBG) sensing system with a high optical SNR of >50 dB.

A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.

With computer application popularizing and storage capacity increasing, research for NAS and SAN storage system are gradually turning to OBS. The OBS will become the next wave of network storage technology. In this paper a framework for accessing general object storage (GOS) is presented. The GOS system adopts a basic unit called storage device object (SDO) and proposes an access model that contains upper layer, middle layer and lower layer. It not only enriches the concept of object, but also gives a compatible object interface in the network storage systems. So it allows applications to access to different SDO according their attributes. Therefore it is more universal.

A novel tunable fiber ring laser configuration with hybrid Raman/EDFA configuration is first proposed and demonstrated for realizing high optical SNR of ~60dB, long-distance of ~50km, fiber Bragg grating (FBG) sensing systems.

In this paper, a hybrid Raman and Erbium-doped fiber amplifier (Raman/EDFA) is first proposed for enhancementof the performance of long-distance fiber Bragg grating (FBG) sensor systems. The Raman fiber amplifier is used for achieving low-noise amplification of FBG signals while the EDFA arranged remotely is used for both the compensation of the fiber loss due to long-distance transmission and the illumination of remotely-located FBGsensors as a broadband source by using the residual Raman pump power to generate ASE light and by amplifyingthe transmission light of the FBGs located before the EDFA. Such a sensor system adopts the advantages of thelow noise feature ofthe distributed Raman amplifier and the high small-signal gain ofthe EDFA. Experimentalresults show that the performance of the sensor system has been improved significantly. A signal-to-noise ratio (SNR) of l3dB has been achieved for a 50km transmission distance, which is l0dB higher than that without amplification.

In this letter, we present a novel sensor approach allowing fast measurement of temperature. It consists of a chirped fibre Bragg grating (CFBG) and an extrinsic Fabry-Perot interferometric sensor (EFPI) in series. Both EFPI and CFBG are well integrated to provide local strain and temperature information respectively, using wavelength-division-multiplexed (WDM) technique. As the wavelength-shift of the CFBG is detected via intensity variation, the speed for temperature measurement can be very high (

An alternative structure using third-order Raman amplification based on ultralong fiber lasers (UL-FLs) is investigated numerically to further improve the quasi-lossless transmission performance. The performance comparisons on flatness of signal distribution, optical signal–noise ratio (OSNR), and noise figure (NF) among first-order, second-order, and third-order Raman pumping based on UL-FLs are discussed numerically. The results display that the gain distribution is pushed more uniformly along UL-FLs using third-order Raman pumping, which is very useful to further extend the quasi-lossless midspan distance. For transparency transmission, enhanced quasi-lossless transmission could be achieved without sacrifice to OSNR and NF. We also analyze the transmission dynamics of loss-managed fundamental solitons for different pumping configurations. The amplifier span and transmission quality are improved considerably, even for lower dispersion lengths, by employing the proposed scheme.

The influence of the non-local effect on sensing performance in a long-distance Brillouin optical time-domain analyzer (BOTDA) based on bi-directional Raman amplification has been investigated theoretically. The system error induced by the non-local effect worsens with increased powers of probe wave and Raman pump. For smaller Brillouin pump power, the non-local effect is almost independent of Brillouin pump power. For larger Brillouin pump power, the non-local effect deteriorates gradually due to Raman gain saturation and cross-gain modulation (XGM). The purely backward pumping (relative to probe light) is preferable for non-local effect suppression. The frequency-division multiplexing (FDM) and time-division-multiplexing (TDM) technologies exhibit similar performance for suppressing the non-local effect under the same conditions. The sensing range near the far-end (relative to the Brillouin pump) should be appropriately shorter to minimize the non-local effect in FDM and TDM. The physical mechanisms of the non-local effect in long-distance BOTDA with Raman amplification are also shown.

Micro extrinsic Fabry–Perot interferometers (MEFPIs), with cavity lengths of up to ~ 9 μm and maximum fringe contrast of ~ 19 dB, are fabricated by chemically etching Er- and B-doped optical fibers and then splicing the etched fiber to a single-mode fiber, for the first time to the best of our knowledge. The strain and temperature responses of the MEFPI sensors are investigated experimentally. Good linearity and high sensitivity are achieved. Such a type of MEFPI sensor is cost-effective and suitable for mass production, indicating its great potential for a wide range of applications.

A novel modified method for realizing long-distance self-adaptive compensation optical fiber transmission is proposed. Based on the hybrid Raman amplification achieved by combining the original bi-directional Raman pump with a second Raman amplification generated by a fiber laser formed by a fiber Bragg grating pair with high reflectivity, the signal light is amplified effectively and the longest self-adaptive compensation optical fiber transmission distance of 125 km is achieved in experiment for the first time, to the best of our knowledge. In addition, the ON/OFF gain, amplified spontaneous emission noise, noise figure and the signal power distribution characteristics of the system are studied experimentally and theoretically. The experimental results are in good agreement with the theoretical analysis.

We report a Brillouin optical time domain analyzer (BOTDA) based on bi-directional Raman amplification in this paper. With the bi-directional Raman amplification, the loss of the optical fiber and the depletion of Brillouin pump light can be compensated for efficiently, hence the measurement resolution is improved at the end of the optical fiber significantly. The detected signal is stable along the whole length of the sensing fiber, free from the spectral broadening caused by the modulation instability and the problem of uneven ness of detected signals of the conventional BOTDA. The Raman amplification is very useful for enhancing the measurement accuracy. With the bi-directional Raman pump, a temperature resolution of 0.6 ℃ was achieved over a sensing distance of 50 km with a 50 m spatial resolution. The signal-to-noise ratio and the optical signal power distribution characteristics of the system have been studied by experiment.

In this paper, we report novel long-period fibre gratings (LPFGs) written by focused high-frequency CO2 laser pulses. A number of unique characteri stics of such a LPFG, such as stroin, temperature, bend, torsion and transverse-load, etc., are observed by experiment, for the first time to our knowledge. These uni que features are mainly due to the asymmetrical distribution of the refractive i ndex on the cross section of the LPFG induced by high-frequency CO2 l aser puls es. Based on these unique characteristics, we have proposed a novel bend-insensi tive LPFG sensor that could solve the problem of cross-sensitivity between bend and other measurements, a novel torsion sensor that can realize absolute measure ment of twist rate and a load sensor that can achieve simultaneous measurement o f transverse load and temperature using a single LPFG element.

The Brillouin scattering tensers and the stiffening Christoffel equations in (100), (010), and (001) planes of C2v point group crystals are obtained at arbitery wave vector directions. Based on these results, all the independent elastic and piezoelectric constants of LBO crystals are determined by means of Brillouin scattering , and the sound velocity anisotropic curves in the three planes are also shown