ABSTRACT
Objective To assess the outcomes of OASIS iris expander in phacoemulsification surgery of cataract with small pupil.Methods A prospective case-control study was conducted in 22 microcoria cataract patients (22 eyes).And they were randomly divided into group A and B,in which the pupils of group A were dilated by tearing instruments in 13 eyes,and the pupils of group B were dilated using OASIS iris expander in 9 eyes.All patient underwent phacoemulsification with 3.2 mm clear corneal incision and were followed up at postoperative 1 week,1 month,3 months and 6 months.Finally,the best corrected visual acuity (BCVA),intraocular pressure (IOP),corneal endothelial cell counts,pupil size before and after surgery were recorded and analyzed by an independent sample t test.Results All procedures were completed successfully by the same skilled doctor.Intraocular lenses were implanted in capsule completely,and no complications occurred.At 6 months after operation,patients'BCVA in group A (0.41 ± 0.30) and group B (0.77 ± 0.23) was significantly higher than that in group A (0.17 ±0.14) and group B (0.16 ±0.14) before operation,but there was no statistical difference between the two groups (all P ＞0.05);whereas there was no significant change in the IOP of group A and B at 6 months after operation (1 kPa =7.5 mmHg) and before operation [(14.22 ±6.00) mmHg vs.(15.70 ± 5.70) mmHg)] (all P ＞ 0.05).Moreover,corneal endothelial cell counts in group A [(1486 ±718) cells · mm-2] and B [(1246 ±516)cells · mm-2] were significantly smaller than those before operation [(2498 ±564)cells · mm-2 vs.[(2424 ± 640) cells · mm-2],with no significant difference (P=0.091).The postoperative diameter of the pupil in group A [(4.00 ±0.88) mm] and group B [(4.70 ± 1.57) mm] after operation was larger than that in group A [(2.30 ±0.35)mm] and group B [(1.94 ±0.50)mm] before operation,and there was no statistical difference between the two groups (all P ＞0.05).Conclusions OASIS iris expander can help to dilate and hold pupils and does not affect the postoperative visual acuity and intraocular pressure in mlcrocoria cataract phacoemulsification.The postoperative pupils become larger,and it is necessary to pay attention to protect corneal endothelial cell during usage of OASIS iris expander.
ABSTRACT
The morphological, structural and photoluminescence properties of one-dimensional ZnO/HfO2 core-shell nanowires (NWs) with various thicknesses of HfO2 shell layers are studied in detail in this work. The ZnO NWs have been fabricated by a simple hydrothermal method, which are then coated by thin HfO2 shell layers using atomic layer deposition (ALD). The morphological and structural characterization demonstrates that the HfO2 shells with polycrystalline structures grow on the single-crystalline ZnO NWs conformally. Moreover, the ZnO/HfO2 core/shell NWs show remarkable enhanced ultraviolet (UV) emission with increasing thickness of the HfO2 shell layer compared with bare ZnO NWs. The UV emission intensity for the sample with HfO2 shell thickness of â¼16 nm is about 9 times higher than that of bare ZnO NWs. It mainly results from the decreased surface states by surface passivation of the HfO2 shell layer as well as a typical type-I band alignment in the ZnO/HfO2 core/shell structure. A model is also proposed to explain the evolution of the wide visible emission band with the relatively low intensity of the core/shell structures. Our results suggest that the ZnO/HfO2 core/shell structures have potential applications for high-efficiency optoelectronic devices such as UV light-emitting diodes and lasers.
ABSTRACT
Effects of ZnO seed layer annealing temperature on the characteristics of the n-ZnO nanowires/Al(2)O(3)/p-Si heterojunction are investigated. Well-aligned ZnO nanowires (NWs) are grown through a simple hydrothermal method. Both the insertion of Al(2)O(3) buffer layer and the annealing treatment of ZnO seed layer are advantageous for the growth of ZnO NWs. This leads to a relatively high rectification ratio of up to 7.8 × 10(3) at ± 4.0 V in ZnO NWs/Al(2)O(3)/p-Si heterojunction photodetectors. The photoelectrical property of n-ZnO/p-Si photodetectors with an enhanced UV/dark current ratio as high as 30 under a reverse bias of 4.0 V is obtained.
ABSTRACT
The n-ZnO/p-Si heterojunction with an ultrathin Al2O3 buffer layer was prepared by atomic layer deposition. X-ray diffraction revealed that the crystalline quality of (100)-oriented ZnO films was improved with an Al2O3 buffer layer. The n-ZnO/p-Si heterojunction with 5 nm inserted Al2O3 layer shows the best electrical characteristics, with a dark current of 0.5 µA at a reverse bias of -2 V and increasing the photo-to-dark current ratio effectively by 8 times. These results demonstrated that Al2O3 buffer layer with optimized thickness exhibits significant advantages in enhancing the crystal quality of ZnO film and improving the photoelectrical properties of n-ZnO/p-Si photodetectors.
ABSTRACT
ZnO/TiO2 nanolaminates were grown on Si (100) and quartz substrates by atomic layer deposition at 200°C using diethylzinc, titanium isopropoxide, and deionized water as precursors. All prepared multilayers are nominally 50 nm thick with a varying number of alternating TiO2 and ZnO layers. Sample thickness and ellipsometric spectra were measured using a spectroscopic ellipsometer, and the parameters determined by computer simulation matched with the experimental results well. The effect of nanolaminate structure on the optical transmittance is investigated using an ultraviolet-visible-near-infrared spectrometer. The data from X-ray diffraction spectra suggest that layer growth appears to be substrate sensitive and film thickness also has an influence on the crystallization of films. High-resolution transmission electron microscopy images show clear lattice spacing of ZnO in nanolaminates, indicating that ZnO layers are polycrystalline with preferred (002) orientation while TiO2 layers are amorphous.
ABSTRACT
High-quality Ti-doped ZnO films were grown on Si, thermally grown SiO2, and quartz substrates by atomic layer deposition (ALD) at 200°C with various Ti doping concentrations. Titanium isopropoxide, diethyl zinc, and deionized water were sources for Ti, Zn, and O, respectively. The Ti doping was then achieved by growing ZnO and TiO2 alternately. A hampered growth mode of ZnO on TiO2 layer was confirmed by comparing the thicknesses measured by spectroscopic ellipsometry with the expected. It was also found that the locations of the (100) diffraction peaks shift towards lower diffraction angles as Ti concentration increased. For all samples, optical transmittance over 80% was obtained in the visible region. The sample with ALD cycle ratio of ZnO/TiO2 being 20 had the lowest resistivity of 8.874 × 10-4 Ω cm. In addition, carrier concentration of the prepared films underwent an evident increase and then decreased with the increase of Ti doping concentration.
