Design and fabrication of large-mode-area multicore chalcogenide fiber with low bending loss.

Multicore fiber (MCF) has a larger mode-area (LMA) compared to traditional single-core fiber, making it easy to get a mode area of more than 3000 µm2 with an optimized MCF structure. Here, a fine-structured 19-core fiber based on chalcogenide glass was fabricated using a combined method involving extrusion, drilling, and rod-in-tube for the first time. The fiber has a minimum transmission loss of 1.8 dB/m at 6.7 µm. When the bending radius exceeds 6 cm, a low bending loss of about 0.6 dB appears, and the experimental data are in good agreement with the simulation results. In addition, the supermode characteristics of the 19-core fiber are analyzed from both perspectives of simulation and experiment, and these results are perfectly in good agreement. We believe it opens a new way to develop high-power and bend-resisting fiber with such kind of multicore structure.

The Microstructure Evolution Process and Flexural Behaviours of SiC Matrix Ceramic Infiltrated by Aluminium Base Alloy.

In this paper, an infiltration approach was proposed to generate a Ti3Si(Al)C2 transition layer in SiC matrix composites to effectually strengthen SiC ceramics. The infiltration temperature played a significant role in the evolution of the microstructure, phase composition, and flexural behaviours. Molten aluminium base alloy fully penetrated SiC ceramic after infiltration at different experimental temperatures (800-1000 °C). The phases in the reaction layer on the surface of SiC ceramic samples varied with the infiltration temperature. When infiltrated at 800 °C, only SiC and Al phases can be found in SiC composites, whereas at 900 °C, a reaction layer containing Ti3Si(Al)C2 and SiC was produced. The Ti3Si(Al)C2 phase grew in situ on SiC. At 1000 °C, the Ti3Si(Al)C2 phase was unstable and decomposed into TiC and Ti5Si3. The cermet phase Ti3Si(Al)C2 was synthesized at a relatively low temperature. Consequently, the flexural modulus and three-point bending strength of samples infiltrated at 900 °C was enhanced by 1.4 and 2.4 times for the original SiC ceramic, respectively.

Formation mechanism of blemishes in a fiber-optic imaging element.

A rigid fiber-optic imaging element with high fidelity, high resolution, and high contrast is applied in low-level-light night vision and particle detection devices. Any optical fiber in elements is an image transmission unit. However, the independence and integrity of image transmission are disturbed constantly, resulting in blemishes. This paper studies the formation mechanism of the blemishes of rigid fiber-optic imaging elements. The existence of defects with different sizes in or among the optical fibers, and fiber deformation decreasing light transmission ability are simulated theoretically. Then experiments are carried out to verify the simulation results. It is theoretically concluded that a blemish forms when the equivalent sphere radius (RES) of a stone defect is greater than 1.2 µm in a normal fiber, and 1.1 µm in a taper fiber. The RES of a bubble defect is greater than 1.3 µm in the fiber, which can form blemishes. Excessive deformation of fibers behaving as a clad layer with thickness less than 0.3 µm also results in the formation of blemishes. When fiber deformation and the existence of stone are considered, blemishes can occur as long as the size of the stone defect among the fibers is greater than 0.823 µm. The results provide data support and theoretical guidance in solving blemishes and other fixed pattern noises, and significantly improve the engineering and application level of fiber-optic imaging elements.

Out-of-plane displacement measurement for an optical fiber image transmission element using optical flow.

To realize the industrial in-situ deformation detection of an optical fiber image transmission element, a method for out-of-plane displacement detection based on the combination of optical flow and an image spherizing algorithm is presented. After capturing the 2D deformation images, the out-of-plane displacement can be extracted from the in-plane displacement estimated by the optical flow method, which means that the out-of-plane displacement information contained in a 2D image is fully used. The principle of the Brox optical flow method is introduced and the accuracy of the method is proven by comparing test results with the digital image correlation method. Experimental results show that the relative errors and the absolute errors of the measurement are less than 2% and 0.1 µm. Because the optical flow algorithm introduces a time parameter and the smoothness assumption, the new method is more appropriate for dynamic and microscale out-of-plane displacement measurement. Unlike conventional methods, it does not need phase unwrapping or frequency domain conversion during detection and has many attractive characteristics such as nondestructive testing, a simple arrangement, and low errors. This method has been applied to the industrial in-situ monitoring of an optical fiber image transmission element.

Probiotics for the Prevention of Ventilator-Associated Pneumonia: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Ventilator-associated pneumonia (VAP) is a common and serious complication of mechanical ventilation. We conducted a meta-analysis of published randomized controlled trials to evaluate the efficacy and safety of probiotics for VAP prevention in patients who received mechanical ventilation. METHODS: We searched a number of medical literature databases to identify randomized controlled trials that compared probiotics with controls for VAP prevention. The results were expressed as odds ratios (OR) or mean differences with accompanying 95% CIs. Study-level data were pooled by using a random-effects model. Data syntheses were accomplished by using statistical software. RESULTS: Fourteen studies that involved 1,975 subjects met our inclusion criteria. Probiotic administration was associated with a reduction in VAP incidence among all 13 studies included in the meta-analysis (OR 0.62, 95% CI 0.45-0.85; P = .003; I2 = 43%) but not among the 6 double-blinded studies (OR 0.72, 95% CI 0.44-1.19; P = .20; I2 = 55%). We found a shorter duration of antibiotic use for VAP (mean difference -1.44, 95% CI -2.88 to -0.01; P = .048, I2 = 30%) in the probiotics group than in the control group, and the finding comes from just 2 studies. No statistically significant differences were found between the groups in terms of ICU mortality (OR 0.95, 95% CI 0.67-1.34; P = .77; I2 = 0%), ICU stay (mean difference -0.77, 95% CI -2.58 to 1.04; P = .40; I2 = 43%), duration of mechanical ventilation (mean difference -0.91, 95% CI -2.20 to 0.38; P = .17; I2 = 25%), or occurrence of diarrhea (OR 0.72, 95% CI 0.45-1.15; P = .17; I2 = 41%). CONCLUSIONS: The meta-analysis results indicated that the administration of probiotics significantly reduced the incidence of VAP. Furthermore, our findings need to be verified in large-scale, well-designed, randomized, multi-center trials.

High-throughput sequencing analysis of microRNAs in gills of red swamp crayfish, Procambarus clarkii infected with white spot syndrome virus.

MicroRNAs (miRNAs) are important posttranscriptional regulators. They play an important role in the antiviral innate immunity of invertebrates. In the present study, high-throughput small RNAs Illumina sequencing systems were carried out to identify differentially expressed miRNAs (DEMs) in the gills of Procambarus clarkii, which was challenged with white spot syndrome virus (WSSV). Our results identified 11,617 known and 6 novel miRNAs in normal group (NG) and WSSV-challenged group (WG) small RNA libraries. Additionally, 27 DEMs were shown to participate in the antiviral innate immunity of P. clarkii and were significantly upregulated or downregulated. In addition, the results of the KEGG pathway prediction of the DEMs target genes showed that putative target genes of these 27 DEMs were related mainly to the RNA transport pathway, tight junction pathway, mRNA surveillance pathway, regulation actin cytoskeleton pathway, focal adhesion pathway, and MAPK signaling pathway. These results provide important information for future studies about the antiviral innate immunity of crustaceans.

[Mineralogy and genesis of mixed-layer clay minerals in the Jiujiang net-like red soil].

Mineralogy and genesis were investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM) to understand the mineralogy and its genesis significance of mixed-layer clay minerals in Jiujiang red soil section. XRD and FTIR results show that the net-like red soil sediments are composed of illite, kaolinite, minor smectite and mixed-layer illite-smectite and minor mixed-layer kaolinite-smectite. HRTEM observation indicates that some smectite layers have transformed into kaolinite layers in net-like red soil. Mixed-layer illite-smectite is a transition phase of illite transforming into smectite, and mixed-layer kaolinite-smectite is a transitional product relative to kaolinite and smectite. The occurrence of two mixed-layer clay species suggests that the weathering sequence of clay minerals in net-like red soil traversed from illite to mixed-layer illite-smectite to smectite to mixed-layer kaolinite-smectite to kaolinite, which indicates that net-like red soil formed under a warm and humid climate with strengthening of weathering.

[Choice of internal fixation methods for posterior malleolus fracture in both biomechanics and clinical application].

OBJECTIVE: To study the biomechanical effects and the clinical outcome of different internal fixation methods in treating posterior malleolus fractures. METHODS: (1) Biomechaniccal study of 18 pairs of posterior malleolus fracture models was conducted, in which all the cases were divided into 3 groups as I, II and III (n=12), according to different fracture degrees that included specimens with 1/4, 1/3 and 1/2 of articular facets fractured respectively; Each group was further divided into 2 subgroups as group A and group B. Group A was fixed with 2 steel half-thread tensile screws whose diameter was 4.0 mm; and group B was fixed with "T-shaped" steel distal-radius plates and 4 screws. The uploading experiment was carried out by settling the specimen on an experiment machine at its neutral position, and the data were collected and managed. (2) Clinical Applications: 31 cases with closed trimalleolar fractures were treated from 2009.1-2010.12 in our hospital, in which 14 with posterior malleolus fractures ≤ 2 5% of the capital diameter of the tibial plafond were fixed with screws, and 17 with posterior malleolus fractures >25% of the capital diameter of the tibial plafond were fixed with steel plates. Prospective cohort study of these cases were carried out. The outcome was assessed using a Leeds Scoring System. RESULTS: The mechanical fixation strengths of the plates for 1/4, 1/3 and 1/2 facets of posterior malleolus fractures were all higher than those of the screw groups [(4.10 ± 0.13) kN vs. (4.6 0 ± 0.27)kN, (3.20 ± 0.12)kN vs. (4.12 ± 0.14)kN and (1.98 ± 0.18)kN vs. (3.72 ± 0.18)kN, respectively, P<0.05]. For the clinical study ,the mean follow-up period was 12 months (6-18 months), all the cases acquired bone union, and the mean time for healing was 10 weeks ( 8-12 weeks). In the evaluation of therapeutic effects, we found that 28 cases were excellent and 3 good, which was 100% satisfying. CONCLUSION: If only 1/4 of the posterior articular facet is involved, 2 screws are enough to supply the stability; but for the fractures involve more than 1/4 facet, the plate fixation supplies more stable fixation and is superior to simply screws.