Retrospective comparison of photorefractive keratectomy and radial keratotomy

BACKGROUND: The efficacy and predictability of photorefractive keratectomy and radial keratotomy become increasingly relevant. This retrospective study compares one surgeon's experience with photorefractive keratectomy and radial keratotomy over a 3-year period from 1990 to 1993. METHODS: Photorefractive keratectomy was performed on 103 eyes of 76 patients that met the inclusion criteria for the phase IIb, phase III, and phototherapeutic keratectomy studies as delineated by the United States Food and Drug Administration. Radial keratotomy was performed on 117 eyes of 81 patients with up to 9.00 diopters (D) of myopia. RESULTS: In the photorefractive keratectomy group, 83% of the eyes achieved uncorrected visual acuity of at least 20/40; 37% saw 20/20; 88% had a refraction within 1.00 D of emmetropia, and 63% within 0.50 D of emmetropia. For the radial keratotomy group, 85% of the eyes achieved an uncorrected visual acuity of 20/40 or better; 27% saw 20/20; 88% had a refraction within 1.00 D of emmetropia; and 55% within 0.50 D of emmetropia. There were no serious complications, and only one single eye in each of the photorefractive keratectomy and radial keratotomy groups lost two lines or more of spectacle-corrected visual acuity. CONCLUSION: Photorefractive keratectomy and radial keratotomy are both effective procedures, and result in similar refractive outcomes for myopia of -1.00 to -9.00 D.     

Luminescence Characterization of Mg Doped Y2O2S:Ti Long Afterglow Phosphor

Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors decrease gradually with increasing Mg2 ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5 ℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8 ℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S:Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photoluminescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2 ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-xMgxO2S:0.06Ti phosphor.     

示例学习的扩张矩阵理论

本文提出示例学习的一种计算理论,扩张矩阵论.根据这个理论,示例学习中一些主要最优化问题被证明是NP难题,并给出这些难题的近似解法及下界的估计.     

Modulation of human CACO-2 intestinal epithelial cell phenotype by protein kinase C inhibitors

Protein kinase C (PKC) isoforms are altered in colon tumors and upon exposure of intestinal mucosa to nutrients. We evaluated the effects of the PKC inhibitors staurosporine and calphostin C on human Caco-2 intestinal epithelial proliferation, motility, and differentiation. Motility was quantitated by monolayer expansion and the brush border enzymes dipeptidyl dipeptidase (DPDD) and alkaline phosphatase (AP) by synthetic substrate digestion. Staurosporine (0.03-1.0 ng/ml) and calphostin C (10(-12) M-10(-4) M) dose-dependently inhibited monolayer expansion and AP but stimulated DPDD. Proliferation was also inhibited but the effects of each inhibitor on motility, AP, and DPDD were preserved after mitomycin C proliferative blockade, suggesting that these effects were proliferation-independent. PKC inhibitors independently inhibit motility, AP and proliferation in human intestinal Caco-2 epithelial cells, but selectively stimulate the small intestinal differentiation marker DPDD. PKC may regulate small intestinal epithelial differentiation.     

Novel Folded Waveguide Resonator Filter Using Slot Technique

This letter presents a primary investigation into developing a compact and low-loss bandpass filter using novel folded-waveguide resonators with a footprint reduction. A slot coupling between adjacent resonators is introduced, which is characterized using full-wave electromagnetic simulations and verified experimentally. Two two-pole folded-waveguide resonator filters of this type have been designed, fabricated and tested. Simulation and measurement results are presented to validate the design and to show the advantages of this type of filter.     

光谱法快速测定土壤中的多个微量元素

本法采用碳酸钡、氟化锂、石墨粉作缓冲剂，用锑做铅锌的标．用铪作铌的内标，用钯作铍、铬、镧、锶、铜的内标。采用小孔电极，交流电弧做为激发光源，同时测定铅、锡、锌、铍、铬、镧、铌、铜、锶等九个元素。分析数据基本稳定．能达到土壤样品的检出限要求。     

Lactic acid production from dining‐hall food waste by Lactobacillus plantarum using response surface methodology

BACKGROUND: Food waste generally has a high starch content and is rich in nutritional compounds, including lipids and proteins. It therefore represents a potential renewable resource. In this study, dining‐hall food waste was used as a substrate for lactic acid production, and response surface methodology was employed to optimise the fermentation conditions. RESULTS: Lactic acid biosynthesis was significantly affected by the interaction of protease and temperature. Protease, temperature and CaCO₃ had significant linear effects on lactic acid production, while α‐amylase and yeast extract had insignificant effects. The optimal conditions were found to be an α‐amylase activity of 13.86 U g^?1 dried food waste, a protease activity of 2.12 U g^?1 dried food waste, a temperature of 29.31 °C and a CaCO₃ concentration of 62.67 g L^?1, which resulted in a maximum lactic acid concentration of 98.51 g L^?1 (88.75% yield). An increase in inoculum size would be appropriate for accelerating the depletion of initial soluble carbohydrate to enhance the efficiency of α‐amylase in dining‐hall food waste fermentation. CONCLUSION: A suitable regression model for lactic acid production was developed based on the experimental results. Dining‐hall food waste was found to be a good substrate for lactic acid fermentation with high product yield and without nutrient supplementation. Copyright © 2008 Society of Chemical Industry     

Restraining the associations of anthracene fluorophore by chemically linking to poly(methyl methacrylate)

Associations (dimer or aggregate) of anthracene (An) fluorophores tend to interrupt the monomer emission and reduce the quantum yield (Φ_PL); therefore, poly(methyl methacrylate) (PMMA) chain was used in this study to chemically link to anthracene and to block the mutual associations among the anthracene fluorophores. With this aim, the target polymers were prepared by anionic polymerizations with 9,10‐dibromoanthracene/s‐butyllithium as initiating system to proceed polymerizations of methyl methacrylate (MMA) directly or in the presence of 1,1‐diphenylethylene (DPE). Use of DPE before addition of MMA produces stable initiating anionic species and avoids potential side reactions during polymerization; however, it also introduces four β‐phenylene rings around the central anthracene ring, which interfere with the corresponding emission pattern and reduce the Φ_PL (32%) value due to potential interactions between phenylene rings and anthracene. On the contrast, polymerization without participation of DPE results in polymer with central anthracene ring directly connected to two PMMA chains, which gives clean vibronic emission pattern with limited association emissions and enhanced Φ_PL (52%) value. Physical blending of anthracene by PMMA is less efficient to restrain the associations and results in a film of lower Φ_PL (20%). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008