• Archives of Pharmacal Research
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• 제25권2호
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• pp.143-150
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• 2002

Fluorescent probes bound to DNA typically display nanosecond decay times and reveal only nanosecond motions. We extend the time range of measurable DNA dynamics using $[Ru(pby)_2(dppz)]^{2+}$ (bpy=2.2'-bipyridine, dppz=dipyrido[3,2-a2',3'-c]phenazine) (RuBD) which displays a mean lifetime near 90 ns. To test the usefulness of RuBD as a probe for diffusive processes in calf thymus DNA, we compared the efficiencies of fluorescence resonance energy transfer (FRET) using three donors which display lifetimes near 5 ns for acridine orange (AO), 22 ns for ethidum bromide (EB) and 92 ns for RuBD, with nile blue (NB) as the acceptor. The F rster distances for AO-NB, EB-NB and RuBD-NB donor-acceptor pairs were 42.3, 52.3, and $30.6{\;}{\AA}$, respectively. All three donors showed dramatic decreases in fluorescence intensities and more rapid intensity decays with increasing NB concentrations. The intensity decays of AO and EB in the presence of varying concentrations of NB were satisfactorily described by the one-dimensional FRET model without diffusion (Blumen and Manz, 1979). In the case of the long-lifetime donor RuBD, the experimental phase and modulation somewhat deviated from the recovered values computed from this model. The recovered NB concentrations and FRET efficiencies from the model were slightly larger than the expected values, however, the recovered and expected values did not show a significant difference. Thus, it is suggested that the lifetime of RuBD is too short to measure diffusive processes in calf thymus DNA.

• 한국재료학회지
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• 제1권2호
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• pp.99-104
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• 1991

Ta-silicide의 게이트 전극 및 비트라인(bit line)으로의 사용가능성을 알아보기 위하여 As, P, $BF_2$가 $5{\times}10^15cm^-2$의 농도로 이온주입된 다결정 실리콘에 탄탈륨을 스퍼터링으로 증착한 후 급속 열처리로 Ta-silicide를 형성하였다. 형성된 Ta-silicide의 특성은 4-탐침법, X-rayghlwjf, SEM 단면사진과 ${\alpha}$-step으로 조사하였으며, 불순물들의 거동은 Secondary Ion Mass Spectroscopy(SIMS)로 알아보았다. $TaSi_2$의 형성은 $800^{\circ}C$에서 시작하며 $1000^{\circ}C$ 이상에서 완료됨을 알았다. 형성된 $TaSi_2$층으로 out-diffusion 하였다.

• Archives of Pharmacal Research
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• 제15권3호
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• pp.196-203
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• 1992

Intramolecular excimer formation of 1, 3-di(1-pyrenyl)propane (Py-3-Py) and fluorescence polarization of 1, 6-diphenyl-1, 3, 5-hexatriene (DPH) were used to investigate the effects of barbiturates on the fluidity of model membranes of phosphatidycholine (SPMVPC), phosphatidylserine (SPMVPS), and phosphatidylinositol (SPMVPI) fractions of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine cerebral cortex. In a dose-dependent manner, barbiturates decreased the excimer to monomer fluorescence intensity ratio (I'/I) of Py-3-Py and increased the anisotropy(r), rotational relaxation time (P), limiting anisotropy $(r_infty)$, and order parameter (S) of DPH in SPMVPC, SPMVPS and SPMVPI. This indicates that barbiturates decreased both the lateral and rotational diffusion of the probes in SPMVPC, SPMVPS and SPMVPI. The relative potencies of barbiturates in ordering the membranes were in the order: pentobarbital > hexobarbital > amobarbital > phenobarbital. This order correlates well with the anesthetic potencies of barbiturates and the potencies for enhancement of $\gamma$-aminobutyric acid-stimulated chloride uptake. Thus, it is strongly suggested that a close relationship might exist between the membrane ordering effects of barbiturates and the chloride fluxes across SPMV.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.429-429
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• 2012

To investigate the gettering effect of B-doped n-type monocrystalline silicon wafer, we made the p-n junction by diffusing boron into n-type monocrystalline Si substrate and then oxidized the boron doped n-type monocrystalline silicon wafer by in-situ wet and dry oxidation. After oxidation, the minority carrier lifetime was measured by using microwave photoconductance and the sheet resistance by 4-point probe, respectively. The junction depth was analyzed by Secondary Ion Mass Spectrometry (SIMS). Boron diffusion reduced the metal impurities in the bulk of silicon wafer and increased the minority carrier lifetime. In the case of wet oxidation, the sheet resistance value of ${\sim}46{\Omega}/{\Box}$ was obtained at $900^{\circ}C$, depostion time 50 min, and drive-in time 10 min. Uniformity was ~7% at $925^{\circ}C$, deposition time 30 min, and drive-in time 10 min. Finally, the minority carrier lifetime was shown to be increased from $3.3{\mu}s$ for bare wafer to $21.6{\mu}s$ for $900^{\circ}C$, deposition 40 min, and drive-in 10 min condition. In the case of dry oxidation, for the condition of 50 min deposition, 10 min drive-in, and O2 flow of 2000 SCCM, the minority carrier lifetime of 16.3us, the sheet resistance of ${\sim}48{\Omega}/{\Box}$, and uniformity of 2% were measured.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권5호
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• pp.432-443
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• 2005

Microarray technology has contributed Significantly to the understanding of bacterial genetics and transcriptional regulation. One neglected aspect of this technology has been optimization of microarray-generated signals and quality of generated information. Full genome microarrays were developed for Clostridium acetobutylicum through spotting of PCR products that were designed with minimal homology with all other genes within the genome. Using statistical analyses it is demonstrated that Signal quality is significantly improved by increasing the hybridization volume. possibly increasing the effective number of transcripts available to bind to a given spot, while changes in labeled probe amounts were found to be less sensitive to improving signal quality. In addition to Q-RT-PCR, array validation was tested by examining the transcriptional program of a mutant (M5) strain lacking the pSOL1 178-gene megaplasmid relative to the wildtype (WT) strain. Under optimal conditions, it is demonstrated that the fraction of false positive genes is 1% when considering differentially expressed genes and 7% when considering all genes with signal above background. To enhance genomic-scale understanding of organismal physiology, using data from these microarrays we estimated that $40{\sim}55%$ of the C. acetobutylicum genome is expressed at any time during batch culture, similar to estimates made for Bacillus subtilis.

• Carbon letters
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• 제11권3호
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• pp.224-234
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• 2010

Four activated carbons were produced by two-stage process as followings; semi-carbonization of indigenous biomass waste, i.e. cotton stalks, followed by chemical activation with KOH under various activation temperatures and chemical ratios of KOH to semi-carbonized cotton stalks (CCS). The surface area, total pore volume and average pore diameter were evaluated by $N_2$-adsorption at 77 K. The surface morphology and oxygen functional groups were determined by SEM and FTIR, respectively. Batch equilibrium and kinetic studies were carried out by using a basic dye, methylene blue as a probe molecule to evaluate the adsorption capacity and mechanism over the produced carbons. The obtained activated carbon (CCS-1K800) exhibited highly microporous structure with high surface area of 950 $m^2/g$, total pore volume of 0.423 $cm^3/g$ and average pore diameter of 17.8 ${\AA}$. The isotherm data fitted well to the Langmuir isotherm with monolayer adsorption capacity of 222 mg/g for CCS-1K800. The kinetic data obtained at different concentrations were analyzed using a pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The pseudo-second-order model fitted better for kinetic removal of MB dye. The results indicate that such laboratory carbons could be employed as low cost alternative to commercial carbons in wastewater treatment.

• 대한기계학회논문집
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• 제19권1호
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• pp.219-230
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• 1995

The flow characteristics of a two-dimensional offset jet issuing parallel to a rough wall is experimentally investigated by using a split film probe with the modified Stock's calibration method. The mean velocity and turbulent stresses profiles in the up and down-stream locations of the wall-attachment regions are measured and compared with those of the smooth wall attaching offset jet cases. It is found that the wall-attachment region on the rough wall is wider than on the smooth wall for the same offset height and the jet speed. The position of the maximum velocity point is farther away from the wall than that for the smooth wall case because of the thick wall boundary layer established by the surface roughness. It is concluded that the roughness of the wall accelerates the relaxation process to a redeveloped plane wall jet and produces a quite different turbulent diffusion behavior especially near the wall from comparing with the smooth plane wall jet turbulence.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.201-201
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• 2013

ITO는 투명하면서도 전도성이 매우 높은 물질로 디스플레이 분야에서 전극으로 많이 사용된다. 하지만 ITO는 세라믹 물질이기 때문에 공정 단가가 높고, 유연성이 낮아 구부릴 경우 전도성이 파괴되며 충격에도 약하여 flexible한 소자에 적용할 수 없다. 또한 metal diffusion이 잘 일어나는 물질이기 때문에 OLED 소자의 특성을 저해한다. 이와 같은 문제점을 해결하기 위해 ITO를 대체하여 graphene을 이용한 투명전극 연구개발이 활발히 진행되고 있다. Graphene은 높은 mobility와 전도도를 가지고 있으며, 높은 열전도성, Young's modulus, 그리고 mechanical flexibility를 가진 물질이다. 최근에 이러한 장점들로 인해 ITO를 대체하는 물질로서 각광을 받고 있지만 graphene은 Cu, Ni과 같은 금속표면에 한정되어 성장하는 문제점을 가지고 있다. 이 graphene 합성방법은 전사과정을 필요로 하며, 이로 인해 낮은 생산성과 낮은 수율을 야기한다. 최근 높은 생산성을 가지는 graphene 전극을 만들기 위해 Reduced Graphene Oxide (rGO) 연구가 활발히 진행되고 있다. 그러나 rGO는 산화환원 과정에서 전기전도도와 electron mobility가 완벽히 회복되지 못한다는 문제점을 가지고 있다. 그리하여 본 연구에서는 높은 투과도와 높은 전도도를 갖는 graphene 전극을 얻기 위해서 powdered graphene flake를 사용하였다. Graphene flake를 IPA solvent에 분산시키기 위해 sonicator과 homogenizer를 이용하여 Graphene flake solution을 제작하였다. 그리고 uniform한 전극을 만들기 위해 Spray Coating 방법을 이용하여 PET 기판 위에 graphene flake를 증착시켰다. graphene flake를 이용하여 높은 투과도와 낮은 면저항을 갖는 투명전극을 제작하고, 그 특성을 UV-visible spectrophotometer과 four point probe를 이용하여 확인하였다.

• Nuclear Engineering and Technology
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• 제38권3호
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• pp.201-210
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• 2006

This article presents a brief overview of an important area of neutron scattering: the general principles and techniques of elastic, quasielastic and inelastic scattering from a system composed predominately of incoherent scatterers. The methodology is then applied to the study of water, specifically when it is confined in nanometer-scale environments. The confined water exhibits uniquely anomalous properties in the supercooled state. It also nourishes biological functions, and supports essential chemical reactions in living systems. We focus on recent investigations of water encapsulated in nanoporous silica and carbon nanotubes, hydrated water in proteins and water or hydroxyl species incorporated in nanostructured minerals. Through these scientific examples, we demonstrate the advantages derived from the high sensitivity of incoherent neutron spectroscopy to hydrogen atom motions and hydrogen-bond dynamics, aided by rigorous data interpretation method using molecular dynamics simulations or theoretical modelling. This enables us to probe the inter-/intramolecular vibrations and relaxation/diffusion processes of water molecules in a complex environment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.288-291
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• 2002

Application of metal silicides such as TiSi$_2$ and CoSi$_2$ as contacts and gate electrodes are being studied. However, TiSi$_2$ due to the linewidth-dependance, and CoSi$_2$ due to the excessive Si consumption during silicidation cannot be applied to the deep-submicron MOSFET device. NiSi shows no such problems and can be formed at the low temperature. But, NiSi shows thermal instability. In this investigation, NiSi was formed with a Ti-capping layer to improve the thermal stability. Ni and Ti films were deposited by the thermal evaporator. The samples were then annealed in the N$_2$ ambient at 300-800$^{\circ}C$ in a RTA (rapid thermal annealing) system. Four point probe, FESEM, and AES were used to study the thermal properties of Ti-capped NiSi layers. The Ti-capped NiSi was stable up to 700$^{\circ}C$ for 100 sec. RTA, while the uncapped NiSi layers showed high sheet resistance after 600$^{\circ}C$. The AES results revealed that the Ni diffusion further into the Si substrate was retarded by the capping layer, resulting in the suppression of agglomeration of NiSi films.