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Fabrication of Polymeric Hollow Spheres Having Macropores by a Quenching and Sublimation Process
Im, Sang-Hyuk,Park, O-Ok,Kwon, Moo-Hyun The Polymer Society of Korea 2003 Macromolecular Research Vol.11 No.6
We fabricated polymeric hollow spheres having macropores, which combine the advantageous properties of porous materials and hollow spheres. To fabricate such spheres, a polystyrene/methylmethacrylate solution was dispersed in water by vigorously stirring and then the suspension was quenched using liquid nitrogen. Water and methyl methacrylate present in the quenched suspension were readily sublimated by freeze-drying. Conclusively, the hollow-sphere structure and the macropores of its shell were created by the processes of liquid nitrogen-quenching and sublimation of methyl methacrylate domains within the shell, respectively.
Im, Kyungmin,Heo, Jin Hyuck,Im, Sang Hyuk,Kim, Jinsoo Elsevier 2017 Chemical Engineering Journal Vol. No.
<P><B>Abstract</B></P> <P>Ti doped MoO<SUB>2</SUB> nanoparticles with high BET surface area of 135m<SUP>2</SUP>/g were synthesized via scalable solvothermal cracking of polycrystalline MoO<SUB>3</SUB> microparticles prepared by ultrasonic spray pyrolysis. The pristine MoO<SUB>2</SUB> and Ti doped MoO<SUB>2</SUB> nanoparticles showed metallic conductivity, whereas the MoO<SUB>3</SUB> microparticles had semi-conducting behavior. In addition, the Ti doping in MoO<SUB>2</SUB> nanoparticles formed stronger MoO bond than the pristine MoO<SUB>2</SUB> and consequently exhibited improved stability against humidity. Accordingly, the p-i-n type planar CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> perovskite solar cells with Ti doped MoO<SUB>2</SUB> inorganic hole transporting material showed 15.8% of power conversion efficiency at 1 Sun condition (100mW/cm<SUP>2</SUP>) and significantly improved humidity stability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly stable Ti-doped MoO<SUB>2</SUB> nanoparticles were synthesized by solvo-thermal cracking process. </LI> <LI> The p-type Ti-doped MoO<SUB>2</SUB> was used to hole transporting materials for perovskite solar cells. </LI> <LI> The stability of CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> perovskite solar cell was enhanced. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Im, Sun Hyuk,Wang, Zhiqiang,Lim, Soon Sung,Lee, Ok-Hwan,Kang, Il-Jun TaylorFrancis 2017 PHARMACEUTICAL BIOLOGY Vol.55 No.1
<P><B>Abstract</B></P><P><B>Context:</B><I>Sanguisorba officinalis</I> Linne (Rosaceae) is a medicinal plant used traditionally for the treatment of inflammatory and metabolic diseases in Korea, China, and Japan. In our previous study, a 50% ethanol extract inhibited fat accumulation in 3T3-L1 adipocytes.</P><P><B>Objective:</B> This study investigates bioassay-guided fractionation, isolation, and identification of anti-adipogenic bioactive compounds in <I>S. officinalis</I>.</P><P><B>Materials and methods:</B> The bioassay-guided fractionation was conducted using effective differentiation of 3T3-L1 cells into adipocytes (with 50 μg/mL test material for 8 days) to isolate the inhibitory compounds from ethyl acetate fraction of <I>S. officinalis</I> 50% ethanol extract. The cytotoxicity of each fraction and isolated compound was tested using MTT assay (with 25–300 μg/mL test material). Structures of the isolated active compounds were elucidated using <SUP>1</SUP>H NMR, <SUP>13 </SUP>C NMR, HSQC, HMBC, FT-IR, and MS.</P><P><B>Results:</B> An active ethyl acetate fraction obtained with solvent partition of the extract inhibited lipid accumulation (44.84%) on 3T3-L1 cells without cytotoxicity (102.3%) at the concentration of 50 μg/mL. The ethyl acetate fraction was determined to be mainly composed by isorhamnetin-3-<I>O</I>-<SMALL>D</SMALL>-glucuronide (1) and ellagic acid (2). Pure isorhamnetin-3-<I>O</I>-<SMALL>D</SMALL>-glucuronide (IC<SUB>30</SUB> is 18.43 μM) and ellagic acid (IC<SUB>30</SUB> is 19.32 μM) showed lipid accumulation inhibition on 3T3-L1 cells without cytotoxicity (117.5% and 104.3%) at the concentration of 20 μM, respectively.</P><P><B>Discussion and conclusions:</B> These results suggested that <I>S. officinalis</I> is a potential natural ingredient for the prevention of obesity, which may due to bioactive compounds such as isorhamnetin-3-<I>O</I>-<SMALL>D</SMALL>-glucuronide and ellagic acid.</P>
Interference cancellation with a Subspace Projection Algorithm for Global Positioning System
Sang-Yoon Han,Jun Heo,Sung-Hyuk Im,Gyu-In Jee 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
In this paper we present numerical performance of the previously researched subspace projection based interference cancellation algorithm. The numerical analysis is based on real GPS data including carrier and doppler effects. The position errors are represented for both narrow band and wide band jamming signals.
Multiple-Layered Colloidal Assemblies via Dipping Method with an External Electric Field
Im, Sang-Hyuk,Park, O-Ok,Kwon, Moo-Hyun The Polymer Society of Korea 2003 Macromolecular Research Vol.11 No.2
When using the dipping method for crystal formation, mono-layered colloidal crystal structures depend upon the lift-up rate of a glass substrate. The mono-layered colloidal crystals showed the highest quality when the glass substrate was raised at a rate of 3 mm/min at 25 $^{\circ}C$ in a 1 wt% polystyrene colloidal suspension (ethanol medium). In addition, in order to obtain multiple-layered colloidal crystals, an external electric Held was introduced. Multiple-layered colloidal crystals were successfully obtained via this method. The colloidal particles were well ordered over large areas and assembled into a homogeneous structure.
Formation of uniform TiO2 nanoshell on α-alumina nanoplates for effective metallic luster pigments
Sang Hyuk Im,Su Jin Lee,Myoung Sang You 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.9
To synthesize non-corroding effect pigment appearing metallic silver in color, we coated uniform anatase TiO2 nanoshell via sol-gel chemistry. Under the reaction condition using 3M TiCl4 aqueous solution : deionized water : HCl solution=0.75mL : 20 mL : 0 mL, ~50 nm-thick smooth TiO2 nano-shell was fully coated on the surface of α-alumina nanoplates; consequently, the synthesized effect pigments exhibited similar lustering effect and structuring color to commercial effect pigment. Under relatively acidic condition and higher TiCl4 precursor concentration condition (3 M TiCl4 aqueous solution : deionized water :HCl solution=0.75mL : 20 mL : 0.05mL for acidic condition and 1.0 or 1.5mL : 20 mL : 0 mL for higher TiCl4 precursor concentration condition), rougher TiO2 shell was formed.
Sang-Hyuk Im,Do-Sung Yoo,Hae-Kwan Park 대한신경외과학회 2024 Journal of Korean neurosurgical society Vol.67 No.2
Objective : Numerous studies have indicated that early decompressive craniectomy (DC) for patients with major infarction can be life-saving and enhance neurological outcomes. However, most of these studies were conducted by neurologists before the advent of intra-arterial thrombectomy (IA-Tx). This study aims to determine whether neurological status significantly impacts the final clinical outcome of patients who underwent DC following IA-Tx in major infarction. Methods : This analysis included 67 patients with major anterior circulation major infarction who underwent DC after IA-Tx, with or without intravenous tissue plasminogen activator. We retrospectively reviewed the medical records, radiological findings, and compared the neurological outcomes based on the “surgical time window” and neurological status at the time of surgery. Results : For patients treated with DC following IA-Tx, a Glasgow coma scale (GCS) score of 7 was the lowest score correlated with a favorable outcome (p=0.013). Favorable outcomes were significantly associated with successful recanalization after IA-Tx (p=0.001) and perfusion/diffusion (P/D)-mismatch evident on magnetic resonance imaging performed immediately prior to IA-Tx (p=0.007). However, the surgical time window (within 36 hours, p=0.389; within 48 hours, p=0.283) did not correlate with neurological outcomes. Conclusion : To date, early DC surgery after major infarction is crucial for patient outcomes. However, this study suggests that the indication for DC following IA-Tx should include neurological status (GCS ≤7), as some patients treated with early DC without considering the neurological status may undergo unnecessary surgery. Recanalization of the occluded vessel and P/D-mismatch are important for long-term neurological outcomes.
Sang Hwa Moon,Minjin Kim,Sang Hyuk Im 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.84 No.-
Large-sized α-MoO3 nanoplates with 10 100 mm were synthesized by introduction of titanium tetraisopropoxide as TiO2 precursor in hydrothermal solution chemistry. During the hydrothermal synthesis,the TiO2 can be selectively deposited on the (001) facets of h-MoO3 hexagonal rods and on the (001) and/or (010) facet of α-MoO3 re-growing crystals due to the small lattice mismatch between them. Owing tothe TiO2 passivation of the surface of h-MoO3 rods, the h-MoO3 rods are changed to MoO3 tubes becausethe h-MoO3 are dissolved from the inner part of the TiO2 passivated h-MoO3 rods. The TiO2-passivated(001) facets of h-MoO3 rods act as templates for the re-growth of α-MoO3 and consequently producedrectangle-shaped α-MoO3 nanoplates. Simultaneously, the TiO2 passivated on the (001) and/or (010)facet of the re-growing α-MoO3 crystals inhibits the preferred crystal growth to [001] direction andpromoted the crystal growth to [100] direction, thereby yielding plate-shaped α-MoO3. The small α-MoO3nanoplates and rectangle-shaped ones are further grown to larger nanoplates by attachment processand/or continuous growth.