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AIM:To investigate the short-term effectiveness of orthokeratology(ortho-k)on controlling low-to-moderate myopic in Chinese children.METHODS: There were 271 subjects(271 eyes)enrolled in this study. In total, there were 141 cases aged 9.43±1.10 in the ortho-k group and the spherical equivalent refractive errors(SER)were -2.74±1.15D. The patients were examined at 1, 7, 30, and 90d after they started wearing the ortho-k lenses. There were 130 cases aged 9.37±1.00 enrolled in the control group, with the SER -2.88±1.39D, and the examinations occurred at 6, 12mo after they started wearing single-vision spectacles. Myopic progression was estimated from changes of axial length in both groups. The chi-square test, independent samples t-tests, paired t-tests, Spearman analysis were used to compare the data of the two groups. RESULTS: The axial elongation was 0.27±0.17mm in the ortho-k group after 1a which was significantly longer than that before wearing(PPPt-test). There was significant negative correlation between axial elongation and initial age in both groups during the one-year period(ortho-k group: rs=-0.309, Prs=-0.472,P0.36mm in 1a)were 38% in the ortho-k group and 76.5% in the control group, respectively; whereas those of the older group(aged 9.4～12.0)were lower, reaching 24.3% and 12.9% in the ortho-k and control groups. In patients with SER 5.00～6.00D, the axial elongation in ortho-k group was 57.1% lower than that in control group. CONCLUSION: Ortho-k lens is effective to control myopic progression in children with low-to-moderate myopia. In particular, it reduces the percentage of younger children with fast progression and has a better effect of controlling myopic progression with higher degrees of myopia.

Age-related macular degeneration(AMD)is one of the leading causes of senile irreversible blindness. The oxidative stress caused by reactive oxygen species(ROS), as a risk factor of AMD, plays a role in the pathogenesis of AMD. Manganese superoxide dismutase(MnSOD), as one of the first line antioxidant enzymes, could be expressed in retina cells.It has been demonstrated that MnSOD is correlated with AMD and has been confirmed in animals, cellular level, and patients. This article reviewed the recent literatures on the research and progress of the relation between MnSOD and AMD.

Slightly unbalanced grid voltage can cause large unbalanced current and non-characteristic harmonics in threephase uncontrolled rectifier. This study proposes an accurate model to analyse the performance of three-phase uncontrolled rectifier in slightly unbalanced grid. Three appreciative operation modes (three-phase rectifier, doublephase rectifier and single-phase rectifier with discontinuous rectifier current) in slightly unbalanced grid are discussed in detail in this study. Moreover, the closed-form analytical expressions for boundaries of modes are also derived. To further aid the designer, the curves of current unbalance, third harmonic current, output average voltage, output voltage droop and output voltage harmonic as function of loads under the condition of 2% voltage imbalance are illustrated. Then the design procedure of capacitor is given considering the influence of unbalance and harmonics in slightly unbalanced grid. Finally, a design case is expressed. The design results are realised in a 5 kW three-phase uncontrolled rectifier to verify the accuracy of the proposed models. The proposed model provides a tool for rapidly and accurately judging the impact of various loads on the rectifier performance in slightly unbalanced grid. [ABSTRACT FROM AUTHOR]

Two new saponins were isolated from leaves of Panax quinquefolium and their structures were elucidated as 3beta, 12beta, 20S-trihydroxy-25-methoxydammar-23-ene 3-O-{[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[alpha-L-arabinopyranosyl(1-->6)]-beta-D-glucopyranoside (1) and 3beta, 20S-dihydroxy-12beta, 23R-epoxydammar-24-ene 3-O-{[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[beta-D-xylopyanosyl(1-->6)]-beta-D-glucopyranoside (2) on the basis of (1)D and (2)D NMR (including (1)H, (13)C-NMR, (1)H-(1)H COSY, HSQC, TOCSY, HMBC, and NOESY), ESI-MS spectrometry and chemical methods., (Copyright (c) 2008 John Wiley & Sons, Ltd.)