Research Progress in Tunable Fiber Lasers Based on Multimode Interference Filters.

Tunable fiber lasers have the advantages of good beam quality, high integration, and adjustable output wavelength, and they are widely used in fields such as optical fiber communication and optical fiber sensing. The fiber filter is one of the key components of tunable fiber lasers. Among the various filters currently used, multimode interference filters have the advantages of simple structure, convenient implementation, flexible tuning methods, and convenient spectral range design. The structures of multimode interference filters based on multimode fibers, no-core fibers, multi-core fibers, tapered fibers, and other special fibers are introduced in this paper. The working principles and tuning methods are analyzed and the research progress of tunable fiber lasers based on these filters is summarized. Finally, the development trend of tunable fiber lasers based on multimode interference filters is discussed. The rapid development and applications of multimode interference filters can help improve the performance of continuous and pulse lasers as well as promote the practicality of tunable fiber lasers.

Post chemical etching of tapered seven-core fiber sensor for enhanced figure of merit.

A post chemical etching process to a tapered seven-core fiber (TSCF) is proposed and experimentally demonstrated to effectively adjust the mode profiles of high-order supermodes, aimed to improve the figure of merit (FOM). The experimental results show that the FOM of an etched TSCF is as high as 1431.36 1/RIU, a 7.32-times enhancement compared with that of TSCF without etching, provided the TSCF has the same taper waist diameter of 19.20 µm. The proposed method opens a new, to the best of our knowledge, method for optimizing optical fiber sensor performance.

Expression of Matrix Metalloprotein 13 in Injury Model of Articular Chondrocyte in Rabbits and Analysis of Nano-Drug-Loading System.

This study aimed to analyze the application of a responsive nano-drug-loading system in injury model of articular chondrocyte in rabbits, as well as its effect on expression of matrix metalloprotein 13 (MMP13). The nanoprecipitation method was adopted to prepare camptothecin (CPT)-loaded poly ethylene glycol (PEG)-Poly caprolactone (PCL) and PEG-PCL nanoparticles without CPT. Afterward, the above mentioned nano-drug-loaded system was used to treat an in vitro scratch model of articular chondrocytes. According to different treatment plans, they were divided into groups: G0 (administered CPT-PEG-PCL nanomedicine), G1 (administered PEG-PCL drug), G2 (saline control), and G3 (healthy control). Results showed that the drug-loading capacity and efficiency of CPT-PEG-PCL was higher than that of PEG-PCL. The levels of type II collagen and hyaluronic acid in G0 was higher than that in G1 and G2. The levels of type II collagen and hyaluronic acid in G0 were not obviously different from those in G3. The level of MMP13 in G0 was lower than that in G1 and G2 and the level of tissue inhibitor of metalloproteinases 1 (TIMP1) in G0 was higher than that in G1 and G2. The proliferation activity of cells in G0 was higher than that in G1 and G2, but there was no obvious difference when compared with G3. In conclusion, CPT-PEG-PCL has stronger long-term circulation capacity and drug-loading efficiency. It can effectively up-regulate the levels of type II collagen, hyaluronic acid, and TIMP1, as well as reduce the synthesis and secretion of MMP13 and promote the repair of articular cartilage damage.

The efficacy and safety of Xianling Gubao capsules in the treatment of knee osteoarthritis: A protocol for a randomized, double-blind, controlled trial.

BACKGROUND: Knee osteoarthritis (KOA) is a chronic degenerative joint disease, which is the most common type of osteoarthritis. The clinical manifestations are pain, swelling, and dysfunction of the knee joint, which seriously reduces the quality of life of patients and causes a huge social burden. At present, western medicine mainly focuses on symptomatic treatment, such as anti-inflammatory and pain relief, joint cavity injection, joint replacement, etc. The curative effect has certain limitations. Xianling Gubao capsule has some advantages in the treatment of KOA, but it lacks high-quality clinical research to verify it. Therefore, the purpose of this study is to evaluate the efficacy and safety of Xianling Gubao capsule in the treatment of KOA. METHODS: A randomized, double-blind, double-simulation, parallel controlled trial design was used to study the efficacy and safety of Xianling Gubao capsules in the treatment of KOA. The patients were randomly divided into a treatment group and the control group according to 1:1. The treatment group: Xianling Gubao capsule + glucosamine hydrochloride capsule simulation agent treatment; the control group: glucosamine hydrochloride capsule + Xianling Gubao capsule simulation agent treatment. Both groups received standard treatment for 8 weeks and followed up for 30 days. And at the same time, pay attention to its efficacy and safety indicators. Observation indicators include: the western Ontario and McMaster universities osteoarthritis index, hospital for special surgery knee score, liver and kidney function, adverse reactions, etc. Data analysis was performed using SPSS 25.0 software. DISCUSSION: This study will evaluate the efficacy and safety of Xianling Gubao capsule in the treatment of KOA. The results of this experiment will provide evidence support for Xianling Gubao capsule in the treatment of KOA. TRIAL REGISTRATION: OSF Registration number: DOI 10.17605/OSF.IO/ERM9C.

Observation of split evanescent field distributions in tapered multicore fibers for multiline nanoparticle trapping and microsensing.

The optical attractive force in tapered single-mode fibers (SMFs) is usually uniformly distributed around the tapered section and has been found to be important for trapping and manipulating targeted atoms and nanoparticles. In contrast, a peculiar phenomenon of the evanescent field splitting along the azimuth axis can be experimentally observed by tapering a weakly-coupled MCF into a strongly-coupled MCF to generate supermode interference. Moreover, the supermode interference produces a hexagonally distributed evanescent field and its six vertices give rise to the multiline optical attractive force. For such spectral resonances, the optimum extinction ratio for the transmission dips is given by 47.4 dB, this being determined using an index liquid to cover the tapered MCF. The resonant dips move to a greater extent at longer wavelengths, with the optimum tuning efficiency of 392 nm/RIU for index sensing. The split evanescent fields respectively attract the excited upconversion nanoparticles in the liquid to be linearly aligned and running down the tapered region over the fiber surface, emitting green light with 60° symmetry. The charged nanoparticles were periodically self-organized, with a period of around 1.53 µm. The parallel lines, with 60° rotational symmetry, can be useful for (1) indicating the exact locations of the side-cores or orientations of the tapered MCF; (2) as precision alignment keys for micro-optical manipulation; and (3) enhancing the upconversion light, or for use in lasers, coupling back to the MCF. The split evanescent fields can be promising for developing new evanescent field-based active and passive fiber components with nano-structures.

Solution-processed PEDOT:PSS:GO/Ag NWs composite electrode for flexible organic light-emitting diodes.

Flexible organic light emitting diodes (OLEDs) have attracted considerable attention for the reason of light weight, high mechanical flexibility in display and lighting. The most widely used transparent anode indium tin oxide (ITO) is unsuitable for flexible OLEDs because of its easy cracking upon bending. In this paper, we proposed a simple two steps solution processing method to fabricate flexible PEDOT:PSS:GO/Ag NWs composite electrodes. The optimized PEDOT:PSS:GO/Ag NWs composite electrode exhibits an optical transmittance of 88.7% at a wavelength of 550 nm and a low sheet resistance of 17 Ω/sq, which arecomparable to that of ITO. With PEDOT:PSS:GO/Ag NWs composite electrodes, the turn on voltage, current density and maximum brightness of OLEDs based on composite electrode were 2.1 V, 6.2 cd/A and 22894 cd/m2, respectively, which were superior to that OLED based on ITO anode. The enhanced performance of OLEDs based on composite anode mainly attributed to the lower sheet resistance, smoother surface of the composite anode and the far surface plasma resonance (Far SPR) effect, a lower waveguide optical loss because of the introduction of Ag NWs in the electrode.

[Mid-term effectiveness of Coflex interspinous dynamic internal fixation combined with spinal fusion for lumbar disc degeneration].

Objective: To evaluate the effectiveness of Coflex interspinous dynamic internal fixation combined with spinal fusion for lumbar disc degeneration. Methods: The clinical data of 39 patients with two-level lumbar disc degeneration who met the selection criteria between June 2010 and December 2011 was retrospectively analyzed. They were divided into group A (20 cases, simple lumbar decompression and fusion) and group B (19 cases, Coflex interspinous dynamic internal fixation combined with spinal fusion) according to different surgical methods. There was no significant difference in age, gender, disease diagnosis, lesion segment, disease duration, Oswestry disability index (ODI), visual analogue scale (VAS) score, and the intervertebral height, foramen intervertebral height (FIH), and range of motion (ROM) of upper operative segment and adjacent segment between the two groups ( P>0.05). ODI and VAS score were used to evaluate the effectiveness before operation and at last follow-up, and the improvement rates were calculated. The intervertebral height [anterior disc height (ADH), middle disc height (MDH), and posterior disc height (PDH)], FIH, and ROM were measured and compared between the two groups. Results: The operation time and intraoperative blood loss in group A were significantly more than those in group B ( P<0.05), and there was no significant difference in hospitalization time between the two groups ( t=0.992, P=0.328). All patients were followed up; the follow-up time was 33-50 months (mean, 40.5 months) in group A and 39-51 months (mean, 42.6 months) in group B. No complication such as displacement, loosening, or rupture of internal fixator was found in both groups. At last follow-up, ODI and VAS score of the two groups significantly improved when compared with preoperative scores ( P<0.05). At last follow-up, there was no significant difference in ODI, VAS score, and improvement rate of ODI between the two groups ( P>0.05); the improvement rate of VAS score in group B was significantly higher than that in group A ( t=2.245, P=0.031). There was no significant difference in the intervertebral height and FIH of the upper operative segment at last follow-up between the two groups and between preoperation and last follow-up in the two groups ( P>0.05). At last follow-up, the ADH of adjacent segment in group B was significantly higher than that in group A, and MDH, PDH, and FIH were significantly lower than those in group A ( P<0.05). Compared with preoperation, the ADH of adjacent segment in group A decreased and MDH, PDH, and FIH increased at last follow-up ( P<0.05), while all indexes in group B did not change significantly ( P>0.05). The ROM of adjacent segment in group A increased significantly at last follow-up ( t=2.318, P=0.026). There was significant difference in ROM of adjacent segment between the two groups ( P<0.05). Conclusion: The mid-term effectiveness of Coflex interspinous dynamic internal fixation combined with spinal fusion is similar to that of simple decompression fusion. For those patients whose adjacent segments of the responsible segments have degeneration but have no symptoms or mild symptoms, this treatment can slow down the adjacent segment degeneration.

Corrigendum to "Moderate Fluid Shear Stress Could Regulate the Cytoskeleton of Nucleus Pulposus and Surrounding Inflammatory Mediators by Activating the FAK-MEK5-ERK5-cFos-AP1 Signaling Pathway".

[This corrects the article DOI: 10.1155/2018/9405738.].

Designing MMI structured beam-splitter in LiNbO3 crystal based on a combination of ion implantation and femtosecond laser ablation.

In this work, the design and numerical study of a MMI-based LiNbO3 beam splitter were presented, with a combination of ion implantation and femtosecond laser ablation as a fabricating strategy. The designed splitters show advantages such as good fabrication tolerance, low insertion loss, compactness, and simple fabrication processes. We also demonstrated that the self-imaging principle could be applied to design low-loss MMI beam splitters for multi-mode input with mode number m = 1 and n>1 by carefully choosing the geometry parameters. The presented fabrication strategy provides an alternative choice for the fabrication of power splitters also with other MMI-based devices in various optical monocrystal chips.

Moderate Fluid Shear Stress Could Regulate the Cytoskeleton of Nucleus Pulposus and Surrounding Inflammatory Mediators by Activating the FAK-MEK5-ERK5-cFos-AP1 Signaling Pathway.

We first applied moderate fluid shear stress to nucleus pulposus cells. The correlation of AP-1 with type II collagen, proteoglycan, Cytokeratin 8 protein, MAP-1, MAP-2, and MAP-4 and the correlation of AP-1 with IL-1ß, TNF-α, IL-6, IL-8, MIP-1, MCP-1, and NO were detected. Our results document that moderate fluid shear stress could activate the FAK-MEK5-ERK5-cFos-AP1 signaling pathway. AP1 could downregulate the construct factors of cytoskeleton such as type II collagen, proteoglycan, Cytokeratin 8 protein, MAP-1, MAP-2, and MAP-4 in nucleus pulposus cell after the fluid shear stress was loaded. AP1 could upregulate the inflammatory factors such as IL-1ß, TNF-α, IL-6, IL-8, MIP-1, MCP-1, and NO in nucleus pulposus cell after the fluid shear stress was loaded. Taken together, our data suggested that moderate fluid shear stress may play an important role in the cytoskeleton of nucleus pulposus and surrounding inflammatory mediators by activating the FAK-MEK5-ERK5-cFos-AP1 signaling pathway, thereby affecting cell degeneration.

miR-155 Inhibits Nucleus Pulposus Cells' Degeneration through Targeting ERK 1/2.

We first investigated the difference in microRNA expression between normal NP cells and degenerative NP cells using gene chip. We have found that the expression of ERK1/2 was decreased with overexpression of miR-155 in normal nucleus pulposus cell. Expression of ERK1/2 was increased with inhibition of miR-155. Overexpression or inhibition of miR-155 had no effects on the expression level of mRNA ERK1/2 in nucleus pulposus cell, which showed that miR-155 affected the expression of pERK1/2 after transcription of ERK1/2 mRNA indicating that ERK1/2 was a new target protein regulated by miR-155. In the degeneration of intervertebral disc, inhibited miR-155 decreased the expressions of extracellular main matrix collagen II and glycosaminoglycan and increased expression of ERK1/2. Taken together, our data suggested that miR-155 was the identified miRNA which regulated NP cells degenerated through directly targeting ERK1/2.

[EFFECT OF VITAMIN C ON APOPTOSIS OF NUCLEUS PULPOSUS CELLS INDUCED BY TUMOR NECROSIS FACTOR a AND SERUM DEPRIVATION].

OBJECTIVE: To explore the effect of Vitamin C (Vit C) on the apoptosis of human nucleus pulposus (NP) cells induced by tumor necrosis factor a (TNF-alpha) and serum deprivation. METHODS: The NP cells were isolated from patients undergoing spine corrective operation by collagenase trypsin. The experiment was divided into 3 groups: Vit C group (group A), TNF-alpha group (group B), and serum deprivation group (group C). Group A was reassigned to Al subgroup (basic medium), A2 subgroup (100 pg/mL Vit C), and A3 subgroup (200 pg/mL Vit C). Group B was reassigned to B0 subgroup (control group), Bi subgroup (100 ng/mL TNF-alpha), B2 subgroup (100 microg/mL Vit C+100 ng/mL TNF-alpha), and B3 subgroup (200 microg/mL Vit C+100 ng/mL TNF-alpha). Group C was reassigned to C0 subgroup (Control group), C1 subgroup (2% FBS), C2 subgroup (2% FBS+100 microg/mL Vit C), and C3 subgroup (2% FBS+200 microg/mL Vit C). After application of 100 pg/mL or 200 microg/mL Vit C for 24 hours, NP cells were stimulated by TNF-alpha and serum deprivation, then the apoptosis rate of NP cells was detected by a flow cytometry, and the gene expressions of the extracellular matrix of NP cells (collagen type I, collagen type II, aggrecan, and Sox9) and apoptosis related genes (p53, FAS, and Caspase 3) were detected by real-time fluoroscent quantitative PCR. Results Group A: Vit C could significantly reduce the apoptosis rate and gene expressions of p53, FAS, and Caspase 3 of NP cells in A2 and A3 subgroups when compared with Al subgroup (P<0.05), but there was no significant difference between A2 subgroup and A3 subgroup (P>0.05); Vit C could promote the expressions of the extracellular matrix (collagen type I, collagen type II, aggrecan, and Sox9) of NP cells in a concentration dependent manner (P<0.05). Group B: TNF-alpha significantly increased the apoptosis rate and the gene expressions of p53, FAS, and Caspase 3 in B1 subgroup when compared with B0 subgroup (P<0.05); however, Vit C significantly increased the apoptosis rate and the gene expressions in B2 subgroup, and significantly decreased them in B3 subgroup when compared with B1 subgroup (P<0.05). Group C: 2% FBS significantly increased the apoptosis rate of NP cells and significantly reduced the gene expressions of p53, FAS, and Caspase 3 in C1 subgroup when compared with C0 subgroup (P<0.05); Vit C could significantly reduce the apoptosis rate and gene expressions of p53, FAS, and Caspase 3 in C3 subgroup, but it could significantly increase them in C2 subgroup when compared with C1 subgroup (P<0.05). CONCLUSION: Vit C can promote the synthesis and secretion of extracellular matrix of NP cells. 200 microg/mL Vit C may delay the apoptosis induced by TNF-alpha and serum deprivation, indicating the potential therapeutic effect of Vit C on intervertebral disc degeneration.

Effect of Osteonecrosis Intervention Rod Versus Core Decompression Using Multiple Small Drill Holes on Early Stages of Necrosis of the Femoral Head: A Prospective Study on a Series of 60 Patients with a Minimum 1-Year-Follow-Up.

INTRODUCTION: The conventional CD used 10 mm drill holes associated with a lack of structural support. Thus, alternative methods such as a tantalum implant, small drill holes, and biological treatment were developed to prevent deterioration of the joint. The treatment of CD by multiple 3.2 mm drill holes could reduce the femoral neck fracture and partial weight bearing was allowed. This study was aimed to evaluate the effect of osteonecrosis intervention rod versus core decompression using multiple small drill holes on early stages of necrosis of the femoral head. METHOD: From January 2011 to January 2012, 60 patients undergoing surgery for osteonecrosis with core decompression were randomly assigned into 2 groups based on the type of core decompression used: (1) a total of 30 osteonecrosis patients (with 16 hips on Steinburg stageⅠ,20 hips on Steinburg stageⅡ) were treated with a porous tantalum rod insertion. The diameter of the drill hole for the intervention rod was 10mm.(2) a total of 30 osteonecrosis patients (with 14 hips on Steinburg stageⅠ,20 hips on Steinburg stageⅡ) were treated with core decompression using five drill holes on the lateral femur, the diameter of the hole was 3.2 mm. The average age of the patient was 32.6 years (20-45 years) and the average time of follow-up was 25.6 months (12- 28 months) in the rod implanted group. The average age of the patient was 35.2 years (22- 43 years) and the average time of follow-up was 26.3 months (12-28 months) in the small drill holes group. RESULTS: The average of surgical time was 40 min, and the mean volume of blood loss was 30 ml in both surgical groups. The average of Harris score was improved from 56.2 ± 7.1 preoperative to 80.2 ± 11.4 at the last follow-up in the rod implanted group (p < 0.05). The mean Harris score was improved from 53.8 ± 6.6 preoperative to 79.7 ± 13.2 at the last follow-up in the small drill holes group (p<0. 05). No significant difference was observed in Harris score between the two groups. At the last follow-up, 28 of 36 hips were at the same radiographic stages as pre-operation, and 8 deteriorated in the rod implanted group. 26 of 34 hips were at the same radiographic stage as pre-operation, and 8 deteriorated in the small drill holes group. No significant difference was observed in radiographic stage between the two groups. There was no favourable result on the outcome of a tantalum intervention implant compared to multiple small drill holes. DISCUSSION: CD via multiple small drill holes would allow similar postoperative load-bearing and seems to result in similar or even better clinical outcome without the prolonged implantation of an expensive tantalum implant. A tantalum rod intervention and core decompression using multiple small drill holes were effective on the stage I hips rather than stage II hips.

Comparative and quantitative proteomic analysis of normal and degenerated human annulus fibrosus cells.

Degeneration of the intervertebral disc (IVD) is a major chronic medical condition associated with back pain. To better understand the pathogenesis of IVD degeneration, we performed comparative and quantitative proteomic analyses of normal and degenerated human annulus fibrosus (AF) cells and identified proteins that are differentially expressed between them. Annulus fibrosus cells were isolated and cultured from patients with lumbar disc herniation (the experimental group, degenerated AF cells) and scoliosis patients who underwent orthopaedic surgery (the control group, normal AF cells). Comparative proteomic analyses of normal and degenerated cultured AF cells were carried out using 2-D electrophoresis, mass spectrometric analyses, and database searching. Quantitative analyses of silver-stained 2-D electrophoresis gels of normal and degenerated cultured AF cells identified 10 protein spots that showed the most altered differential expression levels between the two groups. Among these, three proteins were decreased, including heat shock cognate 71-kDa protein, glucose-6-phosphate 1-dehydrogenase, and protocadherin-23, whereas seven proteins were increased, including guanine nucleotide-binding protein G(i) subunit α-2, superoxide dismutase, transmembrane protein 51, adenosine receptor A3, 26S protease regulatory subunit 8, lipid phosphate phosphatase-related protein, and fatty acyl-crotonic acid reductase 1. These differentially expressed proteins might be involved in the pathophysiological process of IVD degeneration and have potential values as biomarkers of the degeneration of IVD.

Channel waveguide lasers at 1064 nm in Nd:YAG crystal produced by C5⁺ ion irradiation with shadow masking.

We report on the fabrication of channel waveguides in Nd:YAG crystals, using swift C5⁺ ion irradiation with ion energy of 15 MeV and fluence at 5×10¹5 ions/cm². A laser-cut shadow mask of a number of open stripes with varied width was covered on the sample surface during the ion irradiation. Channel waveguides were formed in the Nd:YAG crystal due to the refractive index increase along the ion trajectory. Room temperature waveguide laser oscillations at 1064 nm have been observed under 808 nm optical pumping, with laser slope efficiency at 38% and a maximum output power of 36 mW.

Self-Q-switched waveguide laser based on femtosecond laser inscribed Nd:Cr:YVO(4) crystal.

We report on the self-Q-switched laser operation of a monolithic Nd:Cr:YVO(4) channel waveguide cavity. Femtosecond laser inscription was used to fabricate a buried channel waveguide in the substrate. The Nd:Cr:YVO(4) crystal works as both the gain medium and the saturable absorber, which enables the realization of a self-Q-switched waveguide laser pumped at 808 nm and emitting at 1064 nm. The compact waveguide cavity achieved maximum output powers up to 57 mW, corresponding to a single-pulse energy of 22.8 nJ, at 2.3 MHz repetition rate with a pulse duration of 85 ns.

Proton beam writing of Nd:GGG crystals as new waveguide laser sources.

Focused proton beam writing has been utilized to fabricate optical channel waveguides in Nd:GGG crystals. The 1 MeV proton beam irradiation creates a local modified region with positive refractive index changes at the end of the proton trajectory, in which the channel waveguide could confine the light field in a symmetric way. Room-temperature laser emission has been achieved at 1063.7 nm, with absorbed pump power of 61 mW (at 808 nm). The obtained slope efficiency of the Nd:GGG waveguide laser system is as high as 66%, which is, to our best knowledge, the highest value for integrated lasers from ion beam processed channel waveguide systems.

Low-loss channel optical waveguide fabrication in Nd(3+)-doped silicate glasses by femtosecond laser direct writing.

Optical waveguides were fabricated in neodymium-doped silicate glass by using a low-repetition-rate (1 kHz) femtosecond laser inscription. Two different types of waveguide structure are fabricated. In the first, guiding occurs in the focal spot. In the second, guiding occurs in the region between the two filaments. The near-field intensity distribution, propagation loss, index profile reconstruction, and calculation of the modal intensity distribution by the beam propagation method of these waveguides are presented. On the basis of near-field intensity distribution of the light guided through the waveguides and the propagation loss measurement, the optimum writing conditions such as the pulse energy and scan velocity were determined. The waveguide written with 2.2 µJ pulse energy and 50 µm/s scan velocity shows strong guidance at 632.8 nm, with an index contrast of 7 × 10(-4) and a propagation loss of ~0.8 dB/cm.

Continuous wave waveguide lasers of swift argon ion irradiated Nd:YVO4 waveguides.

We report on the fabrication of planar waveguide in Nd:YVO(4) crystal by using swift Ar(8+) ion irradiation. At room temperature continuous wave (cw) laser oscillation at wavelength of ~1067 nm has been realized through the optical pump at 808 nm with a low threshold of 9.3 mW. The slope efficiency of the waveguide laser system is of 8.5%. The optical-to-optical conversion efficiency is 6.6%.

Thermal optimization and erasing of Nd:YAG proton beam written waveguides.

We report on how the optical and structural properties of Nd:YAG proton beam written waveguides are modified when they experienced annealing treatments from 50 °C to 950 °C. The microstructural changes caused in the vicinity of the nuclear damage region were found to be stable up to 700 °C, so that higher annealing temperatures lead to a complete waveguide erasing. Before this "erasing" temperature, the partial thermal-induced defect recombination reduces the propagation losses, reaching its minimum value (below 1 dB/cm) after a 400 °C thermal annealing.