Serum folate deficiency and hyperhomocysteinemia were associated with an increased risk of AAA in Northeast China. The homozygous (TT) genotype of MTHFR gene mutation may be a crucial hereditary risk factor in AAA.
The purity of the synthesized orbital-angular-momentum (OAM) light in the fiber is inversely proportional to channel crosstalk level in the OAM optical fiber communication system. Here the relationship between the fiber structure and the purity is firstly demonstrated in theory. The graded-index optical fiber is proposed and designed for the OAM light propagation with the purity higher than 99.9%. 16 fiber modes (10 OAM modes) have been supported by a specific designed graded-index optical fiber with dispersion less than 35 ps/(km∙nm). Such fiber design has suppressed the intrinsic crosstalk to be lower than -30 dB, and can be potentially used for the long distance OAM optical communication system.
BackgroundIschemia-reperfusion (I/R) is a critical pathophysiological basis of cognitive dysfunction caused by ischemia stroke. Heme-oxygenase-1 (HO-1) is the rate-limiting enzyme for the elimination of excessive free heme by combining with hemopexin (HPX), a plasma protein that contributes to eliminating excessive free heme during ischemia stroke. This study aimed to elucidate whether HPX could alleviate cognitive dysfunction in rats subjected to cerebral I/R.MethodsRats were randomly divided into five groups: sham, MCAO, Vehicle, HPX and HPX + protoporphyrin IX (ZnPPIX). Cerebral I/R was induced by MCAO. Saline, vehicle, HPX and HPX + ZnPPIX were injected intracerebroventricularly at the moment after reperfusion. Morris water maze (MWM) test was used to detect the learning and cognitive function. Western blot was used to detect the expression of HO-1 in ischemic penumbra. CD31/vWF double labeling immunofluorescence was used to detect the neovascularization in the penumbra hippocampus. The structure and function of blood-brain barrier (BBB) was detected by the permeability of Evans Blue (EB), water content of the brain tissue, the Ang1/Ang2 and VE-cadherin expression.ResultsOur study verified that HPX improved the learning and memory capacity. Hemopexin up-regulated HO-1 protein expression, the average vessel density in the penumbra hippocampus and the VE- cadherin expression but decreased the permeability of EB, the water content of brain tissue and the ratio of Ang1/Ang2. The effects were reversed by ZnPPIX, an inhibitor of HO-1.ConclusionHPX can maintain the integrity of the blood-brain barrier and alleviate cognitive dysfunction after cerebral I/R through the HO-1 pathway.
A compact 2 kHz linewidth single frequency microfiber ring laser is demonstrated. Microfiber, with a diameter of 1.88 μm, which is drawn from an Er(3+)/Yb(3+) co-doped phosphate glass fiber, serves as the gain medium. By using this microfiber, a double-knot resonator with a total length of 1.75 mm is constructed. Based on this resonator, a narrow linewidth single frequency laser with output power higher than 0.95 μW is obtained at the wavelength of 1536.1 nm. The linewidth of this microfiber laser is as narrow as 2 kHz, and the side-mode-suppression ratio is higher than 38 dB.
of photons near a circular ring boundary via successive total internal reflections, whispering gallery mode microcavities exhibit ultrahigh Q factors and extremely small mode volumes, leading to greatly enhanced light-matter interactions. [2][3][4] These superior characteristics make WGM microcavities highly attractive for on-chip optical communications, including microlaser sources, [5,6] active filters, [7] optical sensors, [8,9] and others. Using WGM microcavities as resonant cavities for laser oscillations, the light energy density in microcavities is quite high, which results in the reduction of laser thresholds down to the microwatt range. [10][11][12] With an extremely high quality factor and facile processability, inorganic glasses are the most reliable materials for building WGM lasers. In the 1990s, near-infrared lasers were demonstrated in Nd 3+ -doped glass microspheres. [12] Since then, using amorphous glass microcavities to generate lasers with RE-ions has been well established. [11,[13][14][15] Furthermore, various kinds of lasers, such as Raman lasers [16] and second harmonics, [17,18] have been developed by applying glass WGM resonators. However, unlike crystals, glasses are amorphous, and they are characterized by relatively large phonon energy and broad phonon energy distribution, which are detrimental to the luminescence of rare earth (RE) ions that serve as the emission centers. Combining the low phonon energy of the crystalline phase with the excellent mechanical and chemical stability of the oxide matrix, the oxyfluoride nanocrystallized glass ceramic (NGC) has been regarded as an ideal host material for RE ions. [19] However, WGM laser output from NGC microcavities has not yet been reported. The main reason is that the absorption and scattering loss increase rapidly with the growth of nanocrystals in the glass matrix, resulting in the reduction of cavity Q factors that hinders low threshold laser output. To address these obstacles, we carefully designed an excellent oxyfluoride NGC material, where NaYF 4 nanocrystals are crystallized within the borosilicate glass matrix through a controlled heat-treatment process.Since the refractive index of the nanocrystal matches well with the glass matrix, and the sizes of the precipitated nanocrystals are small and uniform, the rise in absorption and scattering losses, which are very harmful to Q factors, are prevented. As a result, Er 3+ -doped NGC microsphere cavities with Q factors as high as 10 6 are obtained, which enables single mode WGM Nanocrystallized glass ceramics (NGCs) are important optical materials, but few studies have focused on their laser actions. Here, by precipitation of NaYF 4 nanocrystals enriched with Er 3+ ions in an oxide glass matrix, great enhancement of the luminescence properties for the NGC microspheres is realized. By carefully matching the refractive index of the glass matrix with that of the NaYF 4 nanocrystals and controlling the size and distribution of the precipitated nanocrystals, the absorption and Rayleigh scat...
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