Inferior oblique weakening surgery on ocular torsion in congenital superior oblique palsy

AIM: To investigate changes in fundus excyclotorsion after inferior oblique myectomy or myotomy. METHODS: The records of 21 patients undergoing strabismus surgery by a single surgeon between 2009 and 2012 were examined. Only patients who had undergone an inferior oblique myectomy or myotomy,with or without horizontal rectus muscle surgery, were evaluated. Digital fundus photographs were obtained,and the angle formed by a horizontal line passing through the optic disc center and a reference line connecting the foveola and optic disc center was measured. Associated clinical factors examined include age at the time of surgery, presence or absence of a head tilt, degree of preoperative vertical deviation,torsional angle, inferior oblique muscle overaction/superior oblique muscle underaction, and surgery laterality. Whether the procedure was performed alone or in combination with a horizontal rectus muscle surgery was also examined. RESULTS: Mean preoperative torsional angle was12. 0 ± 6. 4 °, which decreased to 6. 9 ± 5. 7 ° after surgery(P 【0.001, paired t-test). Torsional angle also decreased from 15. 1 ± 7. 0 ° to 6. 2 ± 4. 3 ° in the myectomy group(P 【0.001, paired t-test) but there were no significant changes in the myotomy group(P =0.093, Wilcoxon signed rank test). Multivariable linear regression analysis showed that preoperative torsional angle, degree ofinferior oblique overaction, and age at surgery independently and significantly affected postoperative torsional angle.CONCLUSION: Mean torsional angle decreased after inferior oblique myectomy. Degree of preoperative torsional angle, inferior oblique overaction, and age at surgery influence postoperative torsional angle.

Intraocular medulloepithelioma in children: clinicopathologic features itself hardly differentiate it from retinoblastoma

Dear Editor,Iam Di: Jinho Lee from the Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea. I am writing to present five case series of intraocular medulloepithelioma. Medulloepitheliomas are the second most common type of pediatric intraocular tumors. They display clinical characteristics similar to retinoblastomas, such as leukocorias and intraocular endophytic masses, and are extremely difficult to clinically differentiate from retinoblastomas.

Comparative Study of Various Preparation Methods of Colloidal Silica

Colloidal silica can be prepared by various methods and starting materials including ion exchange of aqueous silicates, hydrolysis and condensation of silicon compounds, direct oxidation of silicon, and milling and peptization of silica powder. Various silica sols having particle sizes of 10-60 nm prepared by these methods and the preparation methods have been compared on the basis of their shape, size uniformity, sphericity, stability against pH variation, cation concentration, and price, etc. Silica sol prepared from tetraethoxysilane affords uniform size control and growth, and high purity, despite the relatively high costs. Silica sol prepared from liquid silicates affords relatively easy size and shape control;however, it is difficult to lower the alkali content to a level that is appropriate for carrying out semiconductor chemical mechanical polishing processes;in addition, the waste water treatment carried out for recovering the ion exchange resin gives rise environmental consideration. The properties of colloidal silica prepared from fumed silica powder by milling and dispersion depend on the starting silica source and it is relatively difficult to obtain monodispersed particles using this method. Colloidal silica prepared from silicon by direct oxidation has a monodispersed spherical shape and purity control with reasonable prices. It generates less waste water because it can be directly produced in relatively high concentrations. The cation fraction located in the particle relative to the free cation in the fluid is relatively lower in the silica sol prepared by the direct oxidation than others. A careful comparison of colloidal silica and the preparation methods may help in choosing the proper colloidal silica that is the most appropriate for the application being considered.

Femtosecond Tm-Ho co-doped fiber laser using a bulk-structured Bi2Se3 topological insulator

We experimentally demonstrate a femtosecond mode-locked thulium-holmium（Tm-Ho） co-doped fiber laser incorporating a saturable absorber（SA） based on a bulk-structured bismuth selenide（Bi2Se3） topological insulator（TI）. The SA was prepared by depositing a mechanically exfoliated Bi2Se3 TI layer onto a side-polished optical fiber platform. Unlike high-quality nano-structured Bi2Se3 TI-based SA, bulk-structured Bi2Se3 with non-negligible oxidation was used as a saturable absorption material for this experimental demonstration due to its easy fabrication process. The saturation power and modulation depth of the prepared SA were measured to be -28.6 W and -13.4%, respectively. By incorporating the prepared SA into a Tm-Ho co-doped fiber ring cavity, stable soliton pulses with a temporal width of - 853 fs could be generated at 1912.12 nm. The 3-dB bandwidth of the mode-locked pulse was measured to be -4.87 nm. This experimental demonstration reaffirms that Bi2Se3 is a superb base material for mid-infrared passive mode-locking even under oxidation.

A Study on the Dynamic Behavior of Wheel-Type Train Propelled by Superconducting Linear Synchronous Motor

This paper deals with a study on the dynamic behavior of 600 km/h wheel-type train propelled by superconducting linear synchronous motor (LSM). This train is of a traditional wheel-on-rail type with traction motors on wheel-bogies. However, for the 600 km/h speed, on the both sides of each vehicle, superconducting LSMs are attached and the ground coils are installed on the guideway. In this case, the guideway irregularities act as disturbance to the vehicle causing deterioration of ride comfort. And besides thrust force, the normal force could be created in superconducting LSM control, which influences vehicle dynamics during running. In this study, to examine the effect of guideway irregularity and normal force on dynamic behavior of proposed train, the vehicle dynamic model is driven and frequency analysis is performed through simulation. The simulation results show that the lateral directional acceleration is mainly influential to ride comfort;however this could be reduced effectively by electromagnetic damping force from linear generator. It is also shown that the normal force effect from superconducting LSM control is limited even though the attractive normal force acts favorably to ride comfort.

A Study on the Sensor Applications for Position Detection and Guideway Monitoring in High Speed Maglev

The high speed maglev is mainly characterized by propulsion using linear synchronous motor (LSM) and vehicle levitation from the guideway surface. In LSM propulsion control, the position detection sensor is used to detect running vehicle position for synchronized current generation. To maintain the stable levitating condition during vehicle running, the irregularity of guideway surface should be monitored by sensors measuring the displacement and acceleration between vehicle and guideway. In this study, the application methods of these sensors in the high speed maglev are investigated and through the experiments by using the small-scale test bed, the validity of examined methods is confirmed.

Femtosecond mode-locking of a fiber laser using a CoSb_3-skutterudite-based saturable absorber

We experimentally demonstrate an ultrafast mode-locker based on a CoSb_3 skutterudite topological insulator for femtosecond mode-locking of a fiber laser. The mode-locker was implemented on a side-polished fiber platform by depositing a CoSb_3∕PVA composite. The measured modulation depth and saturation power for the transverse-electric mode input were ～5% and ～8.7 W, respectively, and ～2.8% and ～10.6 W for the transverse-magnetic mode input. By incorporating this mode-locker into an erbium-doped fiber-based ring cavity, we were able to readily generate mode-locked, soliton pulses having a pulse width of ～833 fs at 1557.9 nm. The 3-dB bandwidth of the output pulses and time-bandwidth product were ～3.44 and 0.353 nm, respectively. To the best of the authors' knowledge, this is the first demonstration of the use of a skutterudite-based saturable absorber for femtosecond mode-locked pulse generation.

Passively Q-switched ytterbium-doped fiber laser using the evanescent field interaction with bulk-like WTe_2 particles

The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method together with Scotch tape. By attaching bulk-like WTe2 particles, which remained on the top of the sticky surface of a small segment of the Scotch tape, to the flat side of a side-polished fiber, a saturable absorber（SA） was readily implemented. A strong saturable absorption was then readily obtained through an evanescent field interaction with the WTe2 particles. The modulation depth of the prepared SA was measured as ~2.18% at 1.03 μm. By incorporating the proposed SA into an all-fiberized ytterbium-doped fiber ring cavity, stable Qswitched pulses were readily achieved.

Investigation of nonlinear optical properties of rhenium diselenide and its application as a femtosecond mode-locker

We investigated the nonlinear optical properties of ReSe2. First, we measured the nonlinear absorption coefficient and the nonlinear refractive index of a ReSe2 thin film using open-aperture(OA) and closed-aperture(CA) Z-scan techniques. ReSe2 was shown to possess both saturable absorption and self-defocusing properties. The nonlinear absorption coefficient of ReSe2 was measured to be-5.67-0.35×103 cm^2∕GW, and its nonlinear refractive index was-2.81-0.13×10-2 cm^2∕GW at 1560 nm. Next, a fiberized saturable absorber(SA) based on ReSe2 was fabricated with a side-polished fiber platform and was tested as an ultrafast mode-locker capable of producing femtosecond pulses operating at a wavelength of 1560 nm. The estimated modulation depth and saturation power are 3.9% and 42 W, respectively, for the transverse electric mode, while they are 2.4% and 53 W for the transverse magnetic mode. Using the prepared SA, stable soliton pulses with a temporal width of 862 fs were produced from an erbium-doped fiber ring cavity. To the best of the authors’ knowledge, this is the first demonstration of using a ReSe2-based SA for femtosecond mode-locked pulse generation.

Multi-redox phenazine/non-oxidized graphene/cellulose nanohybrids as ultrathick cathodes for high-energy organic batteries

Various redox-active organic molecules can serve as ideal electrode materials to realize sustainable energy storage systems. Yet, to be more appropriate for practical use, considerable architectural engineering of an ultrathick, high-loaded organic electrode with reliable electrochemical performance is of crucial importance. Here, by utilizing the synergetic effect of the non-covalent functionalization of highly conductive non-oxidized graphene flakes (NOGFs) and introduction of mechanically robust cellulose nanofiber (CNF)-intermingled structure, a very thick (≈ 1 mm), freestanding organic nanohybrid electrode which ensures the superiority in cycle stability and areal capacity is reported. The well-developed ion/electron pathways throughout the entire thickness and the enhanced kinetics of electrochemical reactions in the ultrathick 5,10-dihydro-5,10-dimethylphenazine/NOGF/CNF (DMPZ-NC) cathodes lead to the high areal energy of 9.4 mWh·cm−2 (= 864 Wh·kg−1 at 158 W·kg−1). This novel ultrathick electrode architecture provides a general platform for the development of the high-performance organic battery electrodes.