Jolly Hong | University of British Columbia (original) (raw)

Papers by Jolly Hong

Objective To investigate the effect of Ghrlein on tyrosine hydroxylase(TH),Bcl-2 and Bax mRNA exp... more Objective To investigate the effect of Ghrlein on tyrosine hydroxylase(TH),Bcl-2 and Bax mRNA expression of the subatantia nigra in 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced mouse model of Parkinson disease. Methods Eighteen healthy male C57BL/6 mice were divided into three groups at random:Control,MPTP and Ghrelin+MPTP.The mice in MPTP group were injected with MPTP(30 mg/kg,i.p.),once daily for five days,with Ghrelin(i.c.v.),2 h before the injection of MPTP,once daily for eight days.As for the Control group,MPTP and ghrelin were replaced by normal saline.The total mRNA of the substantia nigra(SN) was collected to detect the mRNA expression of TH,Bcl-2 and Bax by semi-quantitive reverse transcription polymerase chain reaction. Results Compared with the control group,MPTP induced a reduction of TH mRNA expression(P0.01).Pretreated with ghrelin showed an increase of TH mRNA expression compared with MPTP group(P0.01).MPTP also decreased the ratio of Bcl-2/Bax to 0.47±0.06(P0.01).And ghrelin could reverse the reduction induced by MPTP(P0.01). Conclusion Ghrelin could inhibit the reduction of TH mRNA expression induced by MPTP.The anti-apoptotic pathway might be the mechanism of this neuroprotective effect.

We found that the columns at the neck region of a magnetic recording inductive head slider compos... more We found that the columns at the neck region of a magnetic recording inductive head slider composed of FeTaN and NiFe are tilted from the surface normal when the pole materials are sputtered at a low substrate bias power. The electron diffraction patterns show that [110] texture has not strongly developed in the FeTaN film. We have not observed noticeable voids throughout the film on the slider, which suggests the absence of microshape anisotropy. This observation is consistent with our previous study of FeTaN blanket films. We confirmed lattice distortion in the FeTaN due to Ta and N incorporation into a Fe matrix. No significant difference in microstructure between the film on the head slider and the blanket film is found. Based on all the information we have gathered, such as X-ray spectra, pole figures, and high-resolution electron micrographs, we established the crystallographic relationship between [110] orientation, columnar direction, and incident atomic flux in the case of oblique-incident deposition of FeTaN films.

The microstructural evolution of 22Cr-25Ni-Mo-Nb-N heat-resistant steel after creep under differe... more The microstructural evolution of 22Cr-25Ni-Mo-Nb-N heat-resistant steel after creep under different stresses at 973 K has been systematically investigated. It is found that during short time creep MX and M 23 C 6 predominantly precipitate in the matrix. While with the increase in creep time, Cr 3 Ni 2 SiX and precipitate in the matrix. MX is the main strengthen precipitate in the matrix after long time creep. Due to a fast coarsening rate, M 23 C 6 in the matrix has a little effect on strengthening the matrix. Comparing the MX and M 23 C 6 in the crept sample with those in the aged sample, it could be found that the creep stress can promote the coarsening rate of MX and has hardly any effect on the coarsening of M 23 C 6. The effect of stress on the coarsening of precipitates focuses on the diffusion of solution atoms. Under the condition of stress, the diffusion of Nb is accelerated, while that of C changes little.

Applied microbiology and …, 2003

A gene encoding a cellobiohydrolase (CBH) was isolated from Thermoascus aurantiacus IFO 9748 and ... more A gene encoding a cellobiohydrolase (CBH) was isolated from Thermoascus aurantiacus IFO 9748 and designated as cbh1. The deduced amino acid sequence encoded by cbh1 showed high homology with the sequence of glycoside hydrolase family 7. To confirm the sequence of the gene encoding the CBH, the cloned gene was expressed in the yeast Saccharomyces cerevisiae, in which no cellulase activity was found, and the gene product was purified and subjected to enzymatic characterization. The recombinant enzyme was confirmed as a CBH by analysis of the reaction product and designated as CBHI. Recombinant CBHI retained more than 80% of its initial activity after 1 h of incubation at 65 C and was stable in the pH range 3.0-9.0. The optimal temperature for enzyme activity was about 65 C and the optimal pH was about 6.0. The recombinant enzyme was found to be highly glycosylated and this glycosylation was shown to contribute to the thermostability of the enzyme. CBHI expression was shown to be induced at higher temperature in T. aurantiacus.

Electron beam-induced shrinkage provides a convenient way of resizing solid-state nanopores in Si... more Electron beam-induced shrinkage provides a convenient way of resizing solid-state nanopores in Si(3) N(4) membranes. Here, a scanning electron microscope (SEM) has been used to resize a range of different focussed ion beam-milled nanopores in Al-coated Si(3) N(4) membranes. Energy-dispersive X-ray spectra and SEM images acquired during resizing highlight that a time-variant carbon deposition process is the dominant mechanism of pore shrinkage, although granular structures on the membrane surface in the vicinity of the pores suggest that competing processes may occur. Shrinkage is observed on the Al side of the pore as well as on the Si(3) N(4) side, while the shrinkage rate is observed to be dependent on a variety of factors.

Gastroesophageal reflux disease complicated by Barrett's esophagus (BE) is a major risk factor fo... more Gastroesophageal reflux disease complicated by Barrett's esophagus (BE) is a major risk factor for esophageal adenocarcinoma (EA). However, the mechanisms of the progression from BE to EA are not fully understood. Besides acid reflux, bile acid reflux may also play an important role in the progression from BE to EA. In this study, we examined the role of phosphatidylinositol-specific phospholipase C (PI-PLC) and a novel NADPH oxidase NOX5-S in bile acid-induced increase in cell proliferation. We found that taurodeoxycholic acid (TDCA) significantly increased NOX5-S expression, hydrogen peroxide (H 2 O 2) production, and cell proliferation in EA cells. The TDCA-induced increase in cell proliferation was significantly reduced by U73122, an inhibitor of PI-PLC. PI-PLCβ1, PI-PLCβ3, PI-PLCβ4, PI-PLCγ1, and PI-PLCγ2, but not PI-PLCβ2 and PI-PLCδ1, were detectable in FLO cells by Western blot analysis. Knockdown of PI-PLCγ2 or extracellular signal-regulated kinase (ERK) 2 mitogen-activated protein (MAP) kinase with small interfering RNAs (siRNA) significantly decreased TDCAinduced NOX5-S expression, H 2 O 2 production, and cell proliferation. In contrast, knockdown of PI-PLCβ1, PI-PLCβ3, PI-PLCβ4, PI-PLCγ1, or ERK1 MAP kinase had no significant effect. TDCA significantly increased ERK2 phosphorylation, an increase that was reduced by U73122 or PI-PLCγ2 siRNA. We conclude that TDCAinduced increase in NOX5-S expression and cell proliferation may depend on sequential activation of PI-PLCγ2 and ERK2 MAP kinase in EA cells. It is possible that bile acid reflux present in patients with BE may increase reactive oxygen species production and cell proliferation via activation of PI-PLCγ2, ERK2 MAP kinase, and NADPH oxidase NOX5-S, thereby contributing to the development of EA. Cancer Res; 70(3); 1247-55. ©2010 AACR.

Insertion of Ph2CO into the Y− Cp (Cp= C5H5) bond and two new reactivity patterns of the Cp-subst... more Insertion of Ph2CO into the Y− Cp (Cp= C5H5) bond and two new reactivity patterns of the Cp-substituted alkoxide complexes have been revealed, by which an efficient and convenient method for conversion of the unsubstituted Cp group to the single-carbon-...

Energy and Buildings, 2006

This paper presents a multicriteria decision-making model for lifespan energy efficiency assessme... more This paper presents a multicriteria decision-making model for lifespan energy efficiency assessment of intelligent buildings (IBs). The decision-making model called IBAssessor is developed using an analytic network process (ANP) method and a set of lifespan performance indicators ...

J. Am. Chem. Soc, 1996

Metal-catalyzed oxygen atom-transfer reactions are of fundamental interest in both chemistry and ... more Metal-catalyzed oxygen atom-transfer reactions are of fundamental interest in both chemistry and biology. 1 Detailed investigations of the mechanism of oxygen atom transfer in biological systems have led to the generation of synthetic models capable of performing ...

Proceedings of …, 2007

Advanced new OPC method to improve OPC accuracy for sub-90nm technology. [Proceedings of SPIE 652... more Advanced new OPC method to improve OPC accuracy for sub-90nm technology. [Proceedings of SPIE 6520, 652047 (2007)]. Jaeyoung Choi, Jaehyun Kang, Yeonah Shim, Kyunghee Yun, Jiho Hong, Yongseok Lee, Keeho Kim. Abstract. ...

In this contribution we present some of our recent work on solid-state nanopores, the fabrication... more In this contribution we present some of our recent work on solid-state nanopores, the fabrication of nanopore/electrode structures and how these can be used for single-molecule biosensing applications (DNA, proteins etc.). Examples include bi-potentiostatic experiments with Au/Si 3 N 4 nanopore membranes and a new way of fabricating small metal nanopores with diameters below 20 nm and well-defined pore conductance, based on electrodeposition and ion-current feedback control.

Proceedings of …, 2009

Search for novel multi-functional materials, especially multiferroics, which are ferromagnetic ab... more Search for novel multi-functional materials, especially multiferroics, which are ferromagnetic above room temperature and at the same time exhibit a ferroelectric behavior much above room temperature, is an active topic of extensive studies today. Ability to address an entity with an external field, laser beam, and also electric potential is a welcome challenge to develop multifunctional devices enabled by nanoscience. While most of the studies to date have been on various forms of Bi- and Ba based Ferrites, rare earth chromites are a new class of materials which appear to show some promise. However in the powder and bulk form these materials are at best canted antiferromagnetics with the magnetic transition temperatures much below room temperature. In this presentation we show that thin films of YbCrO3 deposited by Pulsed Laser Deposition exhibit robust ferromagnetic properties above room temperature. It is indeed a welcome surprise and a challenge to understand the evolution of above room temperature ferromagnetism in such a thin film. The thin films are amorphous in contrast to the powder and bulk forms which are crystalline. The magnetic properties are those of a soft magnet with low coercivity. We present extensive investigations of the magnetic and ferroelectric properties, and spectroscopic studies using XAS techniques to understand the electronic states of the constituent atoms in this novel Chromite. While the amorphous films are ferromagnetic much above room temperature, we show that any observation of ferroelectric property in these films is an artifact of a leaky highly resistive material.

Advanced Materials, 2002

the polymerization was carried out at 0 C under nitrogen while stirring for 24 h. The composite w... more the polymerization was carried out at 0 C under nitrogen while stirring for 24 h. The composite was obtained by filtering and washing the reaction mixtures with deionized water, resulting in the conductive emeraldine salt (ES) form of the PANI/MWNT composite. The composite solid was stirred with 3 wt.-% ammonium hydroxide (reagent grade, Aldrich) under nitrogen for 48 h. The emeraldine base (EB) composite was isolated by vacuum filtration and washed with deionized water and methanol. The precipitate was again washed with deionized water until~pH 7 and dried under vacuum at 55 C for 72 h. The ex-situ PANI/MWNT composite film was prepared by first adding MWNT to N-methylpyrrolidinone (NMP) (99 %, HPLC grade, Aldrich) and sonicating at room temperature for 2 days to disperse the carbon nanotubes. The previously synthesized polyaniline, emeraldine base (EB) form, was dissolved completely in NMP. Then the polyaniline solution and the CNT suspension were mixed and sonicated at room temperature for another 2 days. The composite film was cast on a glass substrate or silicon wafer. The film was washed with methanol, and dried in a vacuum oven at 100 C for 24 h. Film doping was carried out by immersing the EB films in an excess amount of 1 M HCl for 24 h. The doped films were then washed with methanol to remove absorbed doping solutions. The films were dried in a vacuum oven at 70 C for 24 h. The film thickness was determined using a Tencor Instrument (alpha-step 200) surface profilometer. HCl-doped polyaniline film and PANI/MWNT composite film were 9.2 lm and 11.5 lm in thickness, respectively. The electrical conductivities of neat and composite films were measured using an Alessi C4S-44 fourpoint probe conductivity system (ASTM F84). The films were found to be ohmic over the region studied. Infrared spectra were recorded on a Nicolet Magna IR-550 spectrophotometer. Samples were dispersed in pressed KBr disks. The morphology of the neat and composite films was studied with a Hitachi H7000 transmission electron microscope (TEM). X-ray patterns were collected on a Scintag XDS 2000 h/h diffractometer equipped with a monochromatic Cu Ka radiation X-ray source (1.54 , 40 kV, and 30 mA). Data were collected at 2h from 5 to 65 under scan rate of 1 min ±1. Elemental analyses were performed by Atlantic Microlabs,