[Exogenous hydrogen sulfide attenuates gastric ischemia-reperfusion injury via activation of K(ATP) channel].

The present study aimed to investigate the protective effect and mechanism of hydrogen sulfide donor NaHS administration against gastric mucosal injury induced by gastric ischemia-reperfusion (GI-R) in rats. GI-R injury was induced by clamping the celiac artery of adult male SD rats for 30 min and followed by reperfusion for 1 h. The rats were randomly divided into sham group, GI-R group, NaHS group, glibenclamide group and pinacidil group. Gastric mucosal damage was analyzed with macroscopic injured area, deep damage was assessed with histopathology scores, and the hydrogen sulfide concentration in plasma was determined by colorimetric method. The results showed that pretreatment of NaHS significantly reduced the injured area and deep damage of the gastric mucosa induced by GI-R. However, NaHS did not significantly alter the levels of hydrogen sulfide in plasma 14 d after NaHS administration. The gastric protective effect of NaHS during reperfusion could be attenuated by glibenclamide, an ATP-sensitive potassium channel (K(ATP)) blocker. However, K(ATP) opener pinacidil inhibited the GI-R-induced injury. These results suggest that exogenous hydrogen sulfide plays a protective role against GI-R injury in rats possibly through modulation of K(ATP) channel opening.

Optical waveguides in Nd:GGG crystals produced by H+ or C3+ ion implantation.

The optical waveguides in neodymium-doped gadolinium gallium garnet crystal are fabricated, to our knowledge for the first time, by either H(+) or C(3+) ion implantation. The reconstructed refractive index profiles of the planar waveguides have shown, in both cases, the typical "enhanced well" + "barrier" distributions. The two-dimensional modal profiles of the channel waveguides, obtained by using an end-face coupling arrangement, are in good agreement with the simulated modal distributions. After moderate thermal annealing at 200 degrees C, the propagation loss of the H- and C-ion-implanted channel waveguides are reduced down to approximately 1.5 and approximately 1.6 dB/cm, respectively, which exhibits acceptable guiding qualities for applications on potential integrated laser generation.

Optical channel waveguide in Nd/Ce codoped YAG laser crystal produced by carbon ion implantation.

Optical channel waveguides in Nd/Ce codoped YAG laser crystal have been fabricated by using mask-assisted carbon ion implantation. The measured waveguide mode distributions were in good agreement with the calculated modal profiles, which implies the feasibility of designable devices. After thermal annealing treatment at 260 degrees C for 30 min in air, the propagation loss of the waveguide was reduced down to approximately 2 dB/cm at a wavelength of 632.8 nm. The microluminescence spectra of the waveguides show that the fluorescence properties of both Ce and Nd ions (including the energy transfer between them) are not significantly affected by the waveguide formation processing, which indicates a fairly good potential for further laser actions in a compact device.

Ion-implanted optical-stripe waveguides in neodymium-doped calcium barium niobate crystals.

We report on the fabrication and characterization of optical-stripe waveguides in neodymium-doped calcium barium niobate (Nd:CBN) crystals by using He ion implantation assisted with a mask. The guided-mode profiles are successfully modeled through numerical simulations. After annealing at 200 degrees C for 30 min, the waveguide propagation loss could be reduced down to ~3 dB/cm. Room-temperature microluminescence and micro-Raman investigations reveal that the crystal bulk features are well preserved in the active volume of the waveguide, suggesting possible applications as integrated photonic devices.

Annealing effect on mono-mode refractive index enhanced RbTiOPO4 waveguides formed by ion implantation.

We reported on the annealing features of the RbTiOPO4 planar waveguides fabricated by 6.0 MeV C3+ ion implantation. The thermal stability of the ion-implanted RbTiOPO4 waveguide was investigated by annealing at different temperatures ranging from 260 degrees C to 650 degrees C. Results revealed that when temperatures are higher than 550 degrees C, annealing caused the refractive indices of both ny and nz a saturation behavior. An increase of the ny refractive index in waveguide region was observed after proper annealing. The low loss planar mono-mode waveguides have been achieved in RbTiOPO4 crystals by applying appropriate ion implantation and annealing conditions.

Ion exchange in KTiOPO4 crystals irradiated by copper and hydrogen ions.

Cs(+)-K+ ion exchanges were produced on KTiOPO4 crystals which is prior irradiated by Cu+ can H+ ions. The energy and dose of implanted Cu+ ions are 1.5 MeV and 0.5 x 10(14) ions/cm2, and that of H+ are 300 keV and 1 x 10(16) ions/cm2, respectively. The temperature of ions exchange is 430 degrees C, and the time range from 15 minutes to 30 minutes. The prism coupling method is used to measure the dark mode spectra of the samples. Compared with results of ion exchange on the sample without irradiations, both the number of guided mode and its corresponding effective refractive index are decreased. The experimental results indicate that the ion exchange rate closely related with the lattice damage and the damage layers formed in the depth of maximum nuclear energy deposition act as a barrier to block the ions diffuse into the sample and the concentration of defects can modify the speed of ion exchange..

1,3,5-Tris{[3-(1H-benzotriazol-1-ylmeth-yl)phen-oxy]meth-yl}-2,4,6-trimethyl-benzene.

In the title compound, C(51)H(45)N(9)O(3), three 1-(1H-benzotriazol-1-ylmeth-yl)-3-phen-yloxy (bmph) ligands are bonded to the central benzene ring in an asymmetric arrangement, two bmph located on one side of the central benzene ring and the other bmph located on the opposite side of the central benzene ring. The dihedral angles between the central benzene ring and the three pendant phenoxy rings are 76.71 (14), 67.81 (13) and 70.67 (16)°. In the crystal structure, one bmph is disordered over two sites in a 0.611 (5):0.389 (5) ratio. Some of the methyl H atoms are equally disordered over two sets of sites. Inter-molecular C-H⋯N hydrogen bonding is present in the crystal structure.

2,4,6-Trimethyl-1,3,5-tris-(morpholino-meth-yl)benzene.

In the title compound, C(24)H(39)N(3)O(3), the H atoms of the methyl groups are disordered over two positions, with site-occupation factors fixed at 0.5. The three morpholino groups are arranged in an asymmetrical fashion with respect to the anchoring mesitylene ring and adopt chair conformations. Inter-molecular C-H⋯π inter-actions link the mol-ecules into a one-dimensional chain structure.

Optical planar waveguide fabricated in Nd:LuVO4 crystal by MeV oxygen implantation.

We report the first time optical planar waveguide fabricated in vanadate laser crystal Nd:LuVO4 by 3.0 MeV oxygen ion implantation with the dose of 6x1014 ions/cm2 at room temperature. After the implantation, an enhanced ordinary refractive index region was formed with a width of about 2.1 microm beneath the sample surface to act as a waveguide structure. The modes were observed at 633 nm, while only one mode was observed at 1539 nm after annealing at 300 degrees C for 60 min in air. The changes of ordinary refractive index in the guiding region were about 4.42% and 4.07% before and after annealing.

Investigation and analysis of a single-mode waveguide formed by multienergy-implanted LiNbO3.

We demonstrate a single-mode waveguide in LiNbO3 by use of both prism and end-face coupling methods. The waveguide is formed by multienergy megaelectron-volt O2+ implantation at room temperature. A bright line is observed only when moderate postimplant annealing was performed. The possible index profile of the waveguide is constructed according to the damage profile of the lattice structure caused by the implantation. Although dark-mode measurement shows that the effective extraordinary index of LiNbO3 is raised in the waveguide layer, results of the analysis indicate that the single guiding mode could be supported by a synergetic effect from both the raised index layer and the low-index barrier. The reduced loss of the waveguide can be attributed to the widened low-index barrier from multienergy implantation.

Lithium niobate channel waveguide at optical communication wavelength formed by multienergy implantation.

Channel waveguides at 1540 nm in X- and Z-cut LiNbO3 are formed by one-step multienergy MeV O2+ implantation. Single perpendicular mode in both planar and channel waveguides is demonstrated. In the ne channel waveguide, double transverse modes are observed because of the large index difference and broad width of the channel. A single transverse mode is obtained in the no channel waveguide. The thickness of the waveguide is less than 2 mum, and the compactness of the waveguide is attributed to the large index difference between the guiding region and the low-index barrier. The mode patterns and the waveguide loss are measured and analyzed. The loss of 0.9 and 0.7 dB/cm are obtained from the no and ne channel waveguides, respectively.

Monomode optical waveguide excited at 1540 nm in LiNbO(3) formed by MeV carbon ion implantation at low doses.

The monomode enhanced-index LiNbO(3) waveguide excited at 1540 nm is reported. X-cut LiNbO(3) crystals were implanted at room temperature by 6.0 MeV C(3+) ions with a dose of 2.0x10(15) ions/cm(2). Low loss planar optical waveguides were obtained and characterized by the prism coupling technique. Four dark modes were observed for extraordinary light at 633 nm, while only one enhanced-index mode was observed at 1540 nm. The propagation loss of the waveguide is 1.01 dB/cm measured with the moving fiber method. Reflectivity calculation method (RCM) was applied to simulate the refractive index profiles in waveguide. The width of waveguide structure induced by carbon ion implantation is ~3.6 microm.

Low propagation loss of the waveguides in fused quartz by oxygen ion implantation.

The planar waveguides have been fabricated in fused quartz by 3.0 MeV oxygen ion implantation at dose of 1x10;15 ions/cm2. The guiding modes were observed at wavelengths of both 633 nm and 1539 nm before and after annealing at 320 masculineC, 450 masculineC and 500 masculineC in 60 min characterized by the prism-coupling method. The width of the waveguide structure induced by oxygen ion implantation is about 3 microns. After suitable annealing, the minimum propagation loss of the waveguide in fused quartz can be reduced to -0.14 dB/cm.

Low propagation loss of the waveguides in fused quartz by oxygen ion implantation: errata.

The calculated data of propagation loss of the waveguide were incorrect. Corrected data show the actual results in the measurements.