• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.466.2-466.2
• /
• 2014

The Quantum dot (QD) solar cells have been under active research due to their high light harvesting efficiencies and low fabrication cost. In spite of these advantages, there have been some problems on the charge collection due to the limitation of the diffusion length. The modification of advanced nanostructure is capable of solving the charge collection problem by increasing diffusion length of electron. One dimensional nanomaterials such as nanorods, nanowires, and nanotubes may enhance charge collection efficiency in QD solar cells. In this study, we synthesized $TiO_2$ anatase nanorod arrays with length of 200 nm by two-step sol-gel method. The morphology and crystal structure for the nanorod were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The anatase nanorods are single-crystalline and possess preferred orientation along with (001) direction. The photovoltaic properties for the heterojunction structure QD solar cells based on the anatase nanorod were also characterized. Compared with conventional $TiO_2$ nanoparticle based QD solar cells, these nanostructure solar cells exhibited better charge collection properties due to long life time measured by transient open circuit studies. Our findings demonstrate that the single crystalline anatase nanorod arrays are promising charge transport semiconductors for heterojunction QD solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.104-107
• /
• 2001

The fabricated La-modified lead titanate (PLT) thin flim without paling treatment was investigated for modulation frequency dependence of pyroelectric properties by the dynamic method. $Pb_{1-x}La_{x}Ti_{1-x/4}O_{3}$ PLT (x=0.1) thin film having 10 mol% La content was deposited on a $Pt/TiO_{x}/SiO_{2}/Si$ substrate by sol-gel method. The PLT(10) thin film exhibits a relatively excellent dielectric property. The pyroelectric coefficient (p) of the PLT(10) thin film is $6.6{\times}10^{-9}C/cm_{2}\cdot K$ without frequency dependence. The figure of merits for the voltage responsivity and specific detectivity are $1.03{\times}10^{-11}C\cdot cm/J$ and $1.46\times 10^{-9}C\cdot cm/J$, respectively. The PLT(10) thin film has voltage responsivity (Rv) of 5.15 V/W at 8 Hz. Noise equivalent power (NEP) and specific detectivity (D*) of the PLT(10) thin film are$9.93{\times}10^{-8}W/Hz^{1/2}$ and $1.81\times 10^{6}cmHz^{1/2}/W$ at the same frequency of 100 Hz, respectively. The results means that PLT thin film having 10 mol % La content is suitable for the sensing materials of pyroelectric IR sensors.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.2
• /
• pp.274-280
• /
• 2005

A chitinase was purified from the culture supernatant of Paenibacillus illinoisensis KJA-424 by protein precipitation, DEAE-Sephadex anion-exchange chromatography, and Sephadex G-150 gel filtration. The molecular weight of the purified chitinase was 54 kDa on SDS-PAGE and activity staining. Optimal pH and temperature were pH 5.0 and 60$^{circ}$C, the presence of 10 ruM Ag$^{+}$ and Hg$^{2+}$ inhibited the activity by $92.1/%$ and $97.7/%$, and the K$_{m}$ and V$_{max}$ values were 1.12 mg chitin mrl and 1.48$\mu$mol GlcNAc min$^{-1}$, respectively. The enzyme hydrolyzed tetramer to dimer, pentamer to dimer and trimer, and hexamer to dimer, trimer and tetramer, indicating an endo-splitting mechanism. The chitinase had no hydrolytic activity toward dimer and trimer. The chitinase inhibited the mycelial growth of Rhizoctonia solani, suggesting an antifungal property.

• Journal of the Korean Chemical Society
• /
• v.24 no.1
• /
• pp.25-33
• /
• 1980

Pyrocatechase as a phenolytic dioxygenase was extracted from the benzoate-induced cells of a soil bacterium, a member of Pseudomonadaceae, and purified partially by DEAE-cellulose ion-exchange chromatography and Sephadex G-75 gel filtration. Final preparation of the enzyme yielding 200 fold purification over the crude extracts showed a specific activity of about 40 ${\mu}moles$ per minute per mg protein based on catechol as the substrate. The enzyme showed a very limited substrate specificity towards catechol for its catalytic activity. Based on the inhibition study with the substrate analogues, it was assumed that ortho dihydroxy groups on the aromatic ring may participate in the enzyme-substrate binding. The $K_m$ value for catechol was obtained as $1.9{\times}10^{-6}M$, and the optimum activity of the enzyme was obtained at the pH range of 7∼10 and $35^{\circ}C$. With SH-group blocking agents the enzyme was inhibited seriously. The activity of enzyme was also inhibited by the addition of some heavy metals, $Ag^+$ and $Cu^{2+}$, but was not affected by EDTA. General property of the enzyme was characterized and the possible nature of the enzyme active center was also discussed.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.25 no.1
• /
• pp.6-22
• /
• 1999

Chitosan oligosaccharide having physiological activity, such as cell proliferation and wound healing, was prepared by NaNO$_2$ oxidation-NaBH$_4$ reduction from natural chitosan. After deamination by NaNO$_2$ oxidation, the reducing-end residue from NaBH$_4$ was converted to alditol unit, and the reduction was checked by MBTH reagent. The resulting chitosan oligosaccharide had a degree of polymeration of 2-6 from HPLC analysis. From moisture absorption test at relative humidity of 43% and 81%, the moisture absorption ability was 63% and 57%. Moisture retention ability at relative humidity of 43%, silica gel emvironment, was 98% and 97% respectively. Cell proliferation was showed In the range of 0.000032~0.01%, wound healing effect was also appeared in the concentration of 2% and 20%. Antioxidative effect ($SC_{50}$/) was 3213 ppm. Chitosan oligosaccharide was compatible with most of ingredients used in cosmetic products.

• Journal of Plant Biology
• /
• v.35 no.1
• /
• pp.91-95
• /
• 1992

Changes of contents of reducing sugar and sucrose and activities of sucrose-phosphate synthase, sucrose synthease and invertase from the leaves of barley (Hordeum vulgare L. cv. Chalssal) seedlings grown at $4^{\circ}C$ were investigated, and the property of acid invertase were also examined. In the seedlings grown at $4^{\circ}C$ for 3 days, the contents of reducing sugar and sucrose were increased to 1.3 and 2.4 times, respectively. Activity of acid invertase was decreased markedly by cold treatment while the activities of sucrosephosphate synthase, sucrose synthase, and alkaline invertase were not changed. In acid phosphatase purified partially by ammonium sulfate fractionation and DEAE-Sephacel column chromatography, the $K_m$ value for sucrose was 9.5 mM and the optimum pH and temperature was 5.5 and $35^{\circ}C$ respectively. This enzyme was supposed to be ${\beta}-fructosidase$ by studies on the substrate specificity and the molecular weight was estimated to be 63 Kd by Sephadex G-200 gel chromatography.graphy.

• Korean Journal of Materials Research
• /
• v.16 no.8
• /
• pp.524-528
• /
• 2006

On the synthesis of Au/$TiO_2$ core-shell structure nanoparticle, the effect of concentration of $Ti^{4+}$ and reaction temperature on the morphology and optical property of Au/$TiO_2$ core-shell nanoparticles is examined. A gold colloid was prepared by $HAuCl_4{\cdot}4H_2O\;and\;C_6H_5Na_3{\cdot}2H_2O$. Titanium stock solution was prepared by mixing solution of titanium(IV) isopropoxide (TTIP) and triethanolamine (TEOA). The concentrations of $Ti^{4+}$ stock solution were adjusted to $10.01{\sim}0.3$ mM, and then the gold colloid is added to the $Ti^{4+}$ stock solution. Au/$TiO_2$ core-shell structure nanoparticles could be prepared by the hydrolysis of the $Ti^{4+}$ stock solution at $80^{\circ}C$. The size of synthesized Au nanoparticles was 15 nm. The thickness of $TiO_2$ shell on the surface of gold particles was about 10 nm. The absorption peak of synthesized Au/$TiO_2$ core-shell nanoparticles shifted towards the red end of the spectrum by about 3 nm because of the formation of $TiO_2$ shell on the surface of gold particles. The good $TiO_2$ shell is produced when $Ti^{4+}$ concentration is varied between 0.01 and 0.05 mM, and reaction temperature is maintained at $80^{\circ}C$. The crystal structure of $TiO_2$ shell was amorphous.

• Korean Journal of Human Ecology
• /
• v.1 no.1
• /
• pp.79-83
• /
• 1992

Cowpea starch which is the main ingredient of Mook(Korean starch gel) was isolated from cowpea and characterized by physico-chemical methods. Gelatinization properties were investigated by using Brabender amylograph. Starch granules were oval-shape and their size range was $5\;-\;25{\mu}m$. Crystalline type observed by X-ray deffraction was C-type. Apparent amylose content was 20.7%, Amylose and amylopectin fractionated from cowpea starch appeared to have vlue value of 0.55 and 0.089, and ${\beta}-amylolysis$ limit of 79.1 and 71.9%, respectively. Brabender amylograph data showed that initial gelatinization temperature of cowpea starch was $75^{\circ}C$. Also, hot and cooled paste viscosity of 8% starch paste were higher than that of 6% paste by more than twice, breakcown value of two different concentration were almost same. However, in the gelation stage, consistancy and setback of 8% starch paste appeared more than 5 times of those of 6% paste.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.5
• /
• pp.721-728
• /
• 2012

The human papillomavirus (HPV) is the main cause of cervical cancer in developing countries. Rapid diagnosis and initiation of treatment of the HPV infection are critical. Various methods have been employed to reduce the immunogenicity of antibodies targeting HPV serotypes. Nanobodies are the smallest fragments of naturally occurring single-domain antibodies with their antigen-binding site compromised into a single domain. Nanobodies have remarkable properties such as high stability, solubility, and high homology to the human VH3 domain. In this study, a phagemid library was employed to enrich for nanobodies against the L1 protein of the human papilloma virus. Binding reactivity of the selected clones was evaluated using phage enzyme-linked immunosorbent assay (phage-ELISA). Finally, two nanobodies (sm5 and sm8) with the best reactivity against the Gardasil vaccine and the purified HPV-16 L1 protein were expressed and purified using a $Ni^+$-NTA column. The accuracy of expression and purification of the nanobodies was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting assays. In vitro studies demonstrated that neutralization was achieved by the selected nanobodies. The ease of generation and unique features of these molecules make nanobodies promising molecules for the new generation of HPV diagnosis and therapy.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.16 no.2
• /
• pp.68-74
• /
• 1983

A moderately halophilic bacterium, Listeria denitrificans HB-38, isolated from mud on the seashore in Sooyoung bay, Pusan, showed the requirement of $4\%$ sodium chloride for cell growth in a medium with salts typical of a marine environment, and showed that of $10\%$ in a medium with salts typical of a terrestrial environment. The optimum temperature and pH for growth were $40^{circ}C$ and pH 7.5 in the medium containing $10\%$ sodium chloride and ions typical of a terrestrial environment. Sodium chloride as a protoplast stabilizer gave more stability than sorbitol or sucrose, meanwhile the protoplast did not require higher concentration of stabilizer than that of E. coli protoplast. Succinic dehydrogenase of HB-38 had a halophilic property showing maximal activity in the presence of $9\%$ sodium chloride. The strain HB-38 did not harbor an extrach-romosomal DNA.