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This is a copy of the slides presented at the meeting but not formally written up for the volume.
New biomolecular-inorganic nanohybrids with two different functions, one from inorganic moiety and the other from biological one were realized by soft chemical methods such as intercalation, coprecipitation and exfoliation-reassembling reactions. Recently we have been focusing on two-dimensional inorganic compounds like layered double hydroxides (LDHs), since they are biocompatible and can be used as gene or drug delivery inorganic nanovehicles. To the best of our knowledge, such inorganic drug delivery vectors are quite different from conventionally developed ones such as viral based vectors, naked DNA, biodegradable polymers,liposomes, and etc, those which are however limitedly used due to their toxicity, immunogenecity, poor integration, and etc. But we found that such disadvantages can be overcome by immobilizing genes or drug molecules into these new inorganic vectors, which consist of non-toxic metal ions with biological compatibility. Since LDHs are anion exchangeable, negatively charged functional biomolecules can be easily intercalated into hydroxide layers of LDHs by soft chemical reaction methods to form bio-LDHs nanohybrids. In such a way they can gain extra stabilization energy due to the electrostatic interaction between inorganic layers, whatever they are anionic or cationic, and counter-charged biomolecules or drugs. We also found that the hydroxide layers of LDHs could protect the intercalated molecules very efficiently. If necessary, inorganic materials, as reservoir and delivery carrier, can be intentionally removed by dissolving them in an acidic or basic media, which offer a way of recovering the encapsulated biomolecules or drugs. The possible roles of inorganic lattice as the gene and drug delivery carrier will be shown by demonstrating the cellular uptake experiments of FITC, fluorophore, with laser scanning confocal fluorescence microscopy as well as of radioactive isotope-labeled ATP-LDH hybrid. As the typical examples for gene and drug delivery systems, As-myc-LDH and MTX-LDH nanohybrids will be demonstrated along with their endocytic mechanism. In addition, nanotoxicity of LDH and other inorganic nanoparticles will be also discussed in detail.
Korea Astronomy and Space Science Institute (KASI) successfully completed the development of Korea Microlensing Telescope Network (KMTNet, Park et al. 2012) in mid-2015, following which it conducted test runs for several months. ‘DEep Ecliptic Patrol of the Southern sky’ (DEEP-South, Moon et al. 2015), which will be used for asteroid and comet studies, will not only characterize targeted asteroids, carrying out blind surveys toward the sweet spots, but will also mine the data of such bodies using the KMTNet archive. We report preliminary lightcurves of four Potentially Hazardous Asteroids (PHAs) from test runs at KMTNet-CTIO in the February - May 2015 period.
We started ‘DEep Ecliptic Patrol of the Southern sky’ (DEEP-South, DS) (Moon et al. 2015) in late 2012, and conducted test runs with the first Korea Microlensing Telescope Network (KMTNet) (Park et al. 2012), a 1.6 m telescope with 18k x 18k CCD stationed at CTIO in early 2015. While the primary objective of DEEP-South is the physical characterization of small Solar System bodies, it is also expected to discover a large number of such bodies, many of them previously unknown. An automated observation scheduling, data reduction and analysis software subsystem called ‘DEEP-South Scheduling and Data reduction System’ (DS SDS) is thus being designed and implemented to enable observation planning, data reduction and analysis with minimal human intervention.
Korea Microlensing Telescope Network (KMTNet) which consists of three identical 1.6 m wide-field telescopes with 18k × 18k CCDs, is the first optical survey system of its kind. The combination of fast optics and the mosaic CCD delivers seeing limited images over a 4 square degrees field of view. The main science goal of KMTNet is the discovery and characterization of exoplanets, yet it also offers various other science applications including DEep Ecliptic Patrol of SOUTHern sky (DEEP-South). The aim of DEEP-South is to discover and characterize asteroids and comets, including Near Earth Objects (NEOs). We started test runs last February after commissioning, and will return to normal operations in October 2015. A summary of early results from the test runs will be presented.
Octamer-binding transcription factor 4 (Oct4) is a critical molecule for the self-renewal and pluripotency of embryonic stem cells. Recent reports have shown that Oct4 also controls cell-cycle progression and enhances the proliferation of various types of cells. As the high proliferation of donor fibroblasts is critical to the production of transgenic pigs, using the somatic cell nuclear transfer technique, we analysed the effect of Oct4 overexpression on the proliferation of porcine fibroblasts and embryos. Porcine endogenous Oct4 cDNA was cloned, sequenced and inserted into an expression vector. The vector was transfected into porcine fibroblasts, and a stable Oct4-overexpressed cell line was established by antibiotic selection. Oct4 expression was validated by the immunostaining of Oct4. Cell morphology was changed to sharp, and both proliferation and migration abilities were enhanced in Oct4-overexpressed cells. Real-time RT-PCR results showed that p16, Bcl2 and Myc were upregulated in Oct4-overexpressed cells. Somatic cell nuclear transfer was performed using Oct4-overexpressed cells, and the development of Oct4 embryos was compared with that of wild-type cloned embryos. The cleavage and blastocyst formation rates were improved in the Oct4 embryos. Interestingly, blastocyst formation of the Oct4 embryos was observed as early as day 5 in culture, while blastocysts were observed from day 6 in wild-type cloned embryos. In conclusion, the overexpression of Oct4 enhanced the proliferation of both porcine fibroblasts and embryos.
A 44-year-old man developed sudden non-fluent aphasia and right hemiplegia due to left striatocapsular infarction (Figure). Neurologic examination revealed gaze deviation to the right with eyes closed, but not with eyes open (Video). There was no spontaneous or gaze-evoked nystagmus, even after elimination of visual fixation. Leftward pursuit was impaired in a craniotopic frame of reference, and horizontal saccades were hypometric in both directions. Head impulse test was normal in the horizontal plane and there were no visual field defects. The contralesional gaze deviation with eye closure persisted for ten days.
This study quantitatively investigated the immediate effects of a photooxidative collagen cross-linking treatment with photosensitizer riboflavin (RF) and 370 nm UVA light in in vitro human corneoscleral collagen fibrils using histology, thickness, scanning electron microscopy, and atomic force microscopy analyses. Twenty 8 × 2 mm corneoscleral strips were dissected sagittally from donor tissue using a scalpel. Four parameters were investigated, including the density, thickness, adhesion force, and stiffness of corneoscleral tissues before and after the collagen cross-linking treatment. The RFUVA-catalyzed collagen cross-linking treatment led to an increase in the density of both corneal (8%) and scleral (23%) stromal collagens. However, there was no difference in corneoscleral thickness. Furthermore, RFUVA-catalyzed collagen cross-linking treatment led to an increased biomechanical response of corneosclera: 25 and 8% increases in corneoscleral stiffness, and 24 and 22% increases in corneoscleral adhesion force. The collagen cross-linking treatment through RF-sensitized photoreaction may cause structural and biomechanical changes in the collagen fibril network of the cornea and the sclera. This is due to narrowing of the interfibrillar spacing and the stromal edema.
This study investigated the inflammatory effect of intraoperative mitomycin C (MMC) on adhesion reformation in human rectus muscles. Ten consecutive patients who underwent medial rectus resection had their postoperative rectus muscles divided into two groups: control group (n = 10) and MMC group (n = 10). In the MMC group, the muscle was soaked for 2 min with MMC, prepared as a 0.2 mg/mL (0.02%) solution. The 0.02% MMC reactions were examined using histological analysis with hematoxylin-eosin (inflammatory response) and Masson's trichrome (collagen fibrils), immunoreactivities of cyclooxygenase-II (inflammatory response), and collagen type I and III, scanning electron microscopy analysis to quantify the diameter and D-periodicity of collagen fibrils, and atomic force microscopy analysis to quantify the diameter, D-periodicity, and adhesion force of collagen fibrils. The rectus muscles treated with 0.02% MMC showed a significantly increased inflammatory response (p < 0.05), increased collagen density (p < 0.0001), increased fibril diameter (p < 0.001 or p < 0.05), and decreased fibril adhesion force (p < 0.005) compared to the rectus muscles in the control group. MMC simultaneously caused an inflammatory response as well as nanostructural and biomechanical property changes in the collagen fibril network.
A combinatory approach of Step-and-Flash Imprint Lithography (SFIL) and Metal-Assisted Chemical Etching (MacEtch) was used to generate near perfectly-ordered, high aspect ratio silicon nanowires (SiNWs) on 4" silicon wafers. The ordering and shapes of SiNWs depends only on the SFIL nanoimprinting mould used, thereby enabling arbitary SiNW patterns not possible with nanosphere and interference lithography (IL) to be generated. Very densely packed SiNWs with periodicity finer than that permitted by conventional photolithography can be produced. The height of SiNWs is, in turn, controlled by the etching duration. However, it was found that very high aspect ratio SiNWs tend to be bent during processing. Hexagonal arrays of SiNW with circular and hexagonal cross-sections of dimensions 200nm and less were produced using pillar and pore patterned SFIL moulds. In summary, this approach allows highlyordered SiNWs to be fabricated on a wafer-level basis suitable for semiconductor device manufacturing.
To compare the characteristics and risk factors for surgical site infections (SSIs) after total hip arthroplasty (THA) and total knee arthroplasty (TKA) in a nationwide survey, using shared case detection and recording systems.
Retrospective cohort study.
Twenty-six hospitals participating in the Korean Nosocomial Infections Surveillance System (KONIS).
From 2006 to 2009, all patients undergoing THA and TKA in KONIS were enrolled.
SSI occurred in 161 (2.35%) of 6,848 cases (3,422 THAs and 3,426 TKAs). Pooled mean SSI rates were 1.69% and 2.82% for THA and TKA, respectively. Of the cases we examined, 42 (26%) were superficial-incisional SSIs and 119 (74%) were “severe” SSIs; of the latter, 24 (15%) were deep-incisional SSIs and 95 (59%) were organ/space SSIs. In multivariate analysis, a duration of preoperative hospital stay of greater than 3 days was a risk factor for total SSI after both THA and TKA. Diabetes mellitus, revision surgery, prolonged duration of surgery (above the 75th percentile), and the need for surgery due to trauma were independent risk factors for total and severe SSI after THA, while male sex and an operating room without artificial ventilation were independent risk factors for total and severe SSI after TKA. A large volume of surgeries (more than 10 procedures per month) protected against total and severe SSI, but only in patients who underwent TKA.
Risk factors for SSI after arthroplasty differ according to the site of the arthroplasty. Therefore, clinicians should take into account the site of arthroplasty in the analysis of SSI and the development of strategies for reducing SSI.
Nitrogen (N) and boron (B) codoped diamond-like carbon (DLC) films were prepared on silicon oxide substrates by RF magnetron sputtering to optimize the electrical conductivity and hardness of DLC film. The electrical conductivity and hardness of the N–B codoped DLC films were controlled simultaneously by varying N2 flow rate with fixed B target power and varying B target power with fixed N2flow rate. The electrical resistivity of the B-doped DLC films showed a cup-shaped relationship with B target power and a U-shaped relationship with the N–B codoped DLC film. However, hardness of the B-doped DLC films showed a decreasing behavior but it was maintained almost constant for the N–B codoped DLC film. These particular electrical and hardness behaviors of the N–B codoped DLC films could be explained by a neutralization effect of N and B codoping.
To evaluate the risk factors for surgical site infection (SSI) after gastric surgery in patients in Korea.
A nationwide prospective multicenter study.
Twenty university-affiliated hospitals in Korea.
The Korean Nosocomial Infections Surveillance System (KONIS), a Web-based system, was developed. Patients in 20 Korean hospitals from 2007 to 2009 were prospectively monitored for SSI for up to 30 days after gastric surgery. Demographic data, hospital characteristics, and potential perioperative risk factors were collected and analyzed, using multivariate logistic regression models.
Of the 4,238 case patients monitored, 64.9% (2,752) were male, and mean age (±SD) was 58.8 (±12.3) years. The SSI rates were 2.92, 6.45, and 10.87 per 100 operations for the National Nosocomial Infections Surveillance system risk index categories of 0, 1, and 2 or 3, respectively. The majority (69.4%) of the SSIs observed were organ or space SSIs. The most frequently isolated microorganisms were Staphylococcus aureus and Klebsiella pneumoniae. Male sex (odds ratio [OR], 1.67 [95% confidence interval (CI), 1.09–2.58]), increased operation time (1.20 [1.07–1.34] per 1-hour increase), reoperation (7.27 [3.68–14.38]), combined multiple procedures (1.79 [1.13–2.83]), prophylactic administration of the first antibiotic dose after skin incision (3.00 [1.09–8.23]), and prolonged duration (≥7 days) of surgical antibiotic prophylaxis (SAP; 2.70 [1.26–5.64]) were independently associated with increased risk of SSI.
Male sex, inappropriate SAP, and operation-related variables are independent risk factors for SSI after gastric surgery.
The mechanical properties of the 1-9 vol % Cu and Cu6Sn5-dispersed 63Sn-37Pb solder alloys were characterized with tensile test. Also, the Cu and Cu6Sn5-dispersed 63Sn-37Pb solder bumps of 760 μm size were fabricated on the Au(5 μm)/Ni(5 μm)/Cu(27 μm) BGA substrates by screen printing process, and their shear strength were characterized with variations of the dwell time at the reflow peak temperature(220°C) and aging time at 150°C. The yield strength and ultimate tensile strength of the 63Sn-37Pb solder alloy increased with dispersion of 1-9 vol % Cu and Cu6Sn5. In general, however, the Cu and Cu6Sn5-dispersed solder bumps exhibited lower shear strengths than those of the 63Sn-37Pb solder bumps The failure surface of the solder bumps after ball shear test could be divided into two regions of slow crack propagation and critical crack propagation, and the shear strength of solder bumps was inversely proportional to the slow crack propagation length.
Fluorescent dyes including Nile Red (NR), fluorescein, rhodamine and 4- (dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) derivatives were investigated to find an application for the organic light emitting device (OLED). Relationship between the molecular structure and optical property was calculated by ab initio (HF and DFT/6-31G*) and semiempirical (AM1/PM3 and INDO/S) calculation methods for the geometry optimization and for the information of electronic transition, respectively. The absorption maximum and the oscillator strength of molecules strongly depended on the molecular dipole moment, especially for the molecules having both strong electron donor and acceptor group. Since the calculated results were comparable with several experimental results, these semiempirical molecular orbital calculation methods could be used as a powerful prediction tool for optical properties of the luminescent molecules.
It has been clearly demonstrated that ATP could be intercalated into inorganic layered double hydroxide (LDH), giving rise to a biomolecular-inorganic nanohybrid with preserving its physico-chemical and biological integrity. It shows a remarkable transfer efficiency of ATP into target cells by alleviating an electrical repulsion at the cell walls due to the neutralization of negative charge of phosphates by positive hydroxide layers. From cellular uptake experiment with laser scanning confocal fluorescence microscopy, it is revealed that the FITC-LDH hybrid is effectively transferred into 293 cells. Such an unique feature of biomolecule-LDH hybrid will open a new field of reserving and delivering genes, drugs and other functional biomolecules.
We have successfully synthesized organic-inorganic and bio-inorganic nanohybrids by applying an intercalation technique systematically to Bi-based cuprate superconductors, Bi2Sr2Cam-1CumOy (m = 1, 2, and 3; BSCCO), and to layered double hydroxides(LDHs), those which are of high importance in terms of basic understanding of intercalation reactions and of their practical applications. The organic-inorganic hybrids were achieved via intercalative complexation of iodine intercalated BSCOO with organic salt of Py-CnH2n+1I (Py = pyridine). The high-Tc superconducting intercalate with its remarkable lattice expansion can be applied as a precursor for superconducting colloids when dispersed in an appropriate solvent. We were also able to demonstrate that the biomolecules stabilized in the interlayer space of LDH retain their chemical and biological integrity. If necessary, LDH, as a reservoir, can be intentionally removed by dissolving it in an acidic media or interlayer biomolecules in LDH can be released via ion-exchange reaction in electrolyte. It is, therefore, concluded that the inorganic LDH can play a role as a good host lattice for gene reservoir or carrier.
The good field-emission properties of carbon nanotubes coupled with their high mechanical strength, chemical stability, and high aspect ratio, make them ideal candidates for the construction of efficient and inexpensive field-emission electronic devices. The fabrication process reported here has considerable potential for use in the development of integrated radio frequency amplifiers or field emission-controllable cold electron guns for field emission displays. This fabrication process is compatible with currently used semiconductor processing technologies. Micropatterned vertically aligned carbon nanotubes were grown on planar Si surface or inside the trenches, using chemical vapor deposition, photolithography, pulsed-laser deposition, reactive ion etching, and the lift-off method. To control the field-emission current by a 3rd electrode, the gate electrode, we grew carbon nanotubes inside the trenches. This triode-type structure is the best to realize the gray-scale carbon nanotube field emission. This carbon nanotube fabrication process can be widely applied for the development of electronic devices using carbon nanotube field emitters as cold cathodes and could revolutionize the area of field-emitting electronic devices such as RF amplifiers and field emission displays.
The syntxhesis, photo-physics, and electroluminescence of new types of Iridium(III)-encapsulated dendrimers are described. Thus, four different iridium complexes [Ir(III)(C^N)2(LX), Blue-DCBP, Green-DCBP, Yellow-DCBP, and Red-DCBP] with ancillary ligand tethered to the CBP dendritic unit were synthesized and investigated for their photo-physical properties. A large enhancement in electroluminescence performance was observed by using these dendrimers as host/dopant hybrid materials in layered emitting diodes. In particular, host/dopant ratio can be systematically adjusted by varying dendritic generations. These results demonstrate that new Ir(III)-encapsulated dendrimers can be used as potential single-layer materials for organic light emitting diodes. Large difference in the intra-molecular charge transfer phosphorescence quantum yields and electroluminescence effiencies were observed among dendriritic generations.
The intercalation into MoO3 with TiO2 nanoparticles has been accomplished via the exfoliating-restacking route. The molybdenum oxide lithiated by LiBH4 is exfoliated in degassed and deionized water. And subsequent restacking of exfoliated MoO3 in the TiO2 nanoparticle solution results in TiO2-pillared MoO3. X-ray diffraction pattern indicates that the TiO2 nanoparticles are successfully intercalated in the interlayer of MoO3. The interlayer expansion of MoO3 with the Ad value of 11.2 Å is consistent with the size of TiO2 nanoparticle. Well-defined (00l) reflections reveal highly ordered lamellar character of TiO2-pillared MoO3. The pre-edge feature in the X-ray absorption spectrum of the TiO2-pillared MoO3 confirms that guest TiO2 in the interlayer of MoO3 is pillared in the form of anatase.
For using as separative membranes based on magnetic selectivity, nanoporous ferrimagnetic membranes of maghemite (γ-Fe2O3) and cobalt ferrite (Fe2CoO4) were prepared by the sol-gel route from ferrofluid colloidal solutions. Their magnetic properties were examined by superconductor quantum interference device (SQUID), and their structures and porous textures were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption-desorption analyses. O2-N2 adsorption and air separation experiments were carried out in order to evidence magnetic interactions in static and dynamic conditions, respectively. A small effect of an external magnetic field on the selectivity of these membranes was observed.