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author:("Im, Sang-yuk")
2.  Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells 
Nature Communications  2016;7:10379.
Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%).
Perovskite solar cells are still plagued by hysteresis, despite the good charge transport properties of the perovskite counterpart. Here, the authors dope the mesoporous TiO2 scaffold with lithium to improve the transport properties of this other important component of solar cells, and reduce the hysteresis.
PMCID: PMC4735553  PMID: 26758549
3.  Long-Term Incidence and Predicting Factors of Cranioplasty Infection after Decompressive Craniectomy 
The predictors of cranioplasty infection after decompressive craniectomy have not yet been fully characterized. The objective of the current study was to compare the long-term incidences of surgical site infection according to the graft material and cranioplasty timing after craniectomy, and to determine the associated factors of cranioplasty infection.
A retrospective cohort study was conducted to assess graft infection in patients who underwent cranioplasty after decompressive craniectomy between 2001 and 2011 at a single-center. From a total of 197 eligible patients, 131 patients undergoing 134 cranioplasties were assessed for event-free survival according to graft material and cranioplasty timing after craniectomy. Kaplan-Meier survival analysis and Cox regression methods were employed, with cranioplasty infection identified as the primary outcome. Secondary outcomes were also evaluated, including autogenous bone resorption, epidural hematoma, subdural hematoma and brain contusion.
The median follow-up duration was 454 days (range 10 to 3900 days), during which 14 (10.7%) patients suffered cranioplasty infection. There was no significant difference between the two groups for event-free survival rate for cranioplasty infection with either a cryopreserved or artificial bone graft (p=0.074). Intergroup differences according to cranioplasty time after craniectomy were also not observed (p=0.083). Poor neurologic outcome at cranioplasty significantly affected the development of cranioplasty infection (hazard ratio 5.203, 95% CI 1.075 to 25.193, p=0.04).
Neurologic status may influence cranioplasty infection after decompressive craniectomy. A further prospective study about predictors of cranioplasty infection including graft material and cranioplasty timing is necessary.
PMCID: PMC3488651  PMID: 23133731
Decompressive craniectomy; Cranioplasty infection; Neurologic outcome; Graft material; Cranioplasty timing
4.  Bilateral Locked Facets at Lower Lumbar Spine Without Facet Fracture: A Case Report 
Korean Journal of Spine  2012;9(3):278-280.
Bilateral locked facets at L4-5 without facet fracture is a rarely known disease. We present a case of a 37-year-old male patient diagnosed as traumatic L4-5 bilateral facets dislocation without facet fracture. We carried out open reduction, epidural hematoma removal, posterior interbody fusion. After surgery, we attained rapid improvement of the neurologic deficits and competent stabilization.
PMCID: PMC4431019  PMID: 25983832
Lumbar spine; Facet dislocation; Locked facet; Bilateral

Results 1-4 (4)