• Journal of Information Processing Systems
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• 제18권1호
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• pp.59-74
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• 2022

During the last decade, the security of digital images has received considerable attention in various multimedia transmission schemes. However, many current cryptosystems tend to adopt a single-layer permutation or diffusion algorithm, resulting in inadequate security. A hierarchical bilateral diffusion architecture for color image encryption is proposed in response to this issue, based on a hyperchaotic system and DNA sequence operation. Primarily, two hyperchaotic systems are adopted and combined with cipher matrixes generation algorithm to overcome exhaustive attacks. Further, the proposed architecture involves designing pixelpermutation, pixel-diffusion, and DNA (deoxyribonucleic acid) based block-diffusion algorithm, considering system security and transmission efficiency. The pixel-permutation aims to reduce the correlation of adjacent pixels and provide excellent initial conditions for subsequent diffusion procedures, while the diffusion architecture confuses the image matrix in a bilateral direction with ultra-low power consumption. The proposed system achieves preferable number of pixel change rate (NPCR) and unified average changing intensity (UACI) of 99.61% and 33.46%, and a lower encryption time of 3.30 seconds, which performs better than some current image encryption algorithms. The simulated results and security analysis demonstrate that the proposed mechanism can resist various potential attacks with comparatively low computational time consumption.

• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.328-333
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• 1999

Susceptibility of 61 strains of Helicobacter pylori to metronidazole was examined by both the disk diffusion method using a cut-off of 15㎜ for resistance and the E test with a cut-off of 8㎎/l. The MIC/sub 50/ and MIC/sub 90/ by the E test were 2 ㎎/l and 256㎎/l, respectively. Metronidazole resistance was found in 22 (36％) out of the 61 H. pylori strains by the E test and in three additional strains by the disk diffusion method. Amongst the latter three isolates, the MICs by the E test were 4 ㎎/l, 6㎎/l, and 6㎎/l, respectively. These figures are one log₂ or half log₂ dilution lower than the cut-off of 8㎎/l recommended as resistance for the E test. All 22 metronidazole resistant H. pylori isolates by the E test that were subjected to random amplified polymorphic DNA (RAPD) fingerprinting showed different DNA fingerprints. Interestingly, >90％ of resistant isolates possess two common DNA bands of 0.4 and 0.9 kb. This study demonstrates that the results of the disk diffusion method for testing H. pylori susceptibility to metronidazole correlates well with that of the E test. The criteria for interpretation need to be internationally standardized so that the results from different centers can be compared.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1996년도 정기총회 및 학술발표회
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• pp.18-18
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• 1996

Bacteriophage T4 endonuclease V initiates the repair of ultraviolet (UV)-induced pyrimidine dimer photoproducts in duplex DNA. The mechanism of DNA strand cleavage involves four sequential steps: linear diffusion along dsDNA, pyrimidine dimer-specific binding, pyrimidine dimer-DNA glycosylase activity, and AP lyase activity. (omitted)

• 대한기계학회논문집A
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• 제32권8호
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• pp.624-632
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• 2008

In this research, we developed new PDMS-glass based microbiochip consisted of the micromixer and microreactor for DNA ligation. The micromixer was composed of a straight channel integrated with nozzles and pillars, and the microreactor was composed of a serpentine channel. We coated the PDMS chip surface with the 0.25wt.% PVP solution to prevent the bubble generation which was caused by the hydrophobicity of the PDMS. The new micomixer was passive type and the mixing was enhanced by a convective diffusion using the nozzle and pillar. The 10.33mm long micromixer showed the good mixing efficiency of 87.7% at 500 l/min flow rate. We could perform the DNA ligation successfully in the microbiochip, and the ligation time was shortened from 4 hours in conventional laboratory method to 5 min in the microbiochip.

• 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.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권2호
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• pp.117-125
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• 2003

Experimental and theoretical works were performed for the separation of large polyelectrolyte, such as DNA, in a column packed with gel particles under the influence of an electric field. Since DNA quickly orient in the field direction through the pores, this paper presents how intraparticle convection affects the residence time distribution of DNAs in the column. The concept is further illustrated with examples from solid -liquid systems, for example, from chromatography Showing how the column efficiency is improved by the use of a n electric field. Dimensionless transient mass balance equations were derived, taking into consideration both diffusion and electrophoretic convection. The separation criteria are theoretically studied using two different Peclet numbers in the fluid and solid phases. These criteria were experimentally verified using two different DNAs via electrophoretic mobility measurements. which showed how the separation position of the DNAs varies in the column in relation to the Peg/Pef values of an individual DNA. The residence time distribution was solved by an operator theory and the characteristic method to yield the column response.

• KSBB Journal
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• 제22권6호
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• pp.387-392
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• 2007

DNA 마이크로어레이는 바이오칩의 발전에서 가장 주목받으며 발전하고 있는 분야로서 이에 대한 연구가 점차 확장하고 있다. DNA나 RNA 등 유전자의 매우 느린 확산속도를 극복하기 위하여 마이크로플루딕 바이오칩이 DNA 마이크로어레이에 적용되는 최근의 학술적인 사례들을 연구, 비교하였다. DNA 마이크로어레이에 적용된 미세유체 바이오칩은 상당수가 효율적인 hybridization을 달성하기 위한 믹싱 시스템이 많이 보고되었으며, 이 총설에서는 그에 대한 분석을 수행하여 유전자 hybridization 강화를 이룬 시스템에 대한 최근 동향을 가늠할 수 있게 하였다. 특별히 PDMS를 이용한 마이크로 펌프의 적용 등, 앞으로의 미세유체 DNA 마이크로어레이 발전가능성과 모델링의 한계점 등을 정리 분석해 보았다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.332-339
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• 2000

Experimental and theoretical works were performed for the separation of large polyelectrolytes such as DNA in the column packed with gel particles under an electric field. This paper shows how intraparticle convection effects the separation of DNAs in the column because DNAs quickly oriented through the pores in the field direction. Dimensionless transient mass balance equations were derived considering diffusion and electrophoretic convection. The separation criteria is theoretically studied using two different Peclet numbers in the fluid and solid phases and these criteria were verified uing two different DNAs by electrophoretic mobilities measured experimentally, showing how the separation position of DNAs varies in the column according to values of Pe(sub)f/Pe(sub)g of individual DNA. Governing equations are simultaneously solved by operator theoretic and characteristic methods to yield the column response.

• Journal of Pharmaceutical Investigation
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• 제37권1호
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• pp.39-43
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• 2007

Previously, we have reported that PLGA nanoparticles were prepared for sustained release of water-soluble blue dextran and the particle size, in vitro release pattern and encapsulation were modulated by varying polymers. This study was designed to encapsulate plasmid DNA in PLGA nanoparticles and to investigate the effect of Polymers and temperatures. PLGA nanoparticles were fabricated with poloxamer 188 (P188) or poloxamer 407 (P407) by using spontaneous emulsification solvent diffusion method. As a model plasmid DNA, pCMV-Taq2B/1L-18 was encapsulated in PLGA nanoparticles. Then, the particle size, zeta potential and encapsulation efficiency of nanoparticles containing plasmid DNA were investigated. Particle sizes of PLGA nanoparticles prepared with P188 and P407 were in the range of 200-330 nm and 250-290 nm, respectively. Zeta potentials of nanoparticles were negative regardless of nanoparticle compositions. Encapsulation efficiency of P407 nanoparticles prepared at $30^{\circ}C$ was higher than those at other preparation condition. From the results, the PLGA nanoparticles prepared with poloxamers at different temperature, could modulate the particles size of nanoparticles, and encapsulation efficiency of plasmid DNA.

• 한국미생물·생명공학회지
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• 제14권3호
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• pp.209-212
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• 1986

YEp 13 plasmid에 B. amyloliquefaciens의 $\alpha$-amylase gene을 cloning시켜서 얻은 hybrid plasmid를 E. coli C 600으로 형질전환시켜서 amylase 활성을 나타내는 균주를 선별하였다. 선별된 E. coli C 600균주를 plasmid추출하여 전기영동해 본 결과 plasmid가 매우 불안정하였으며, 그중 가장 단순한 plasmid band를 지니고 있으며 amylase활성이 강한 E. coli균주를 선별하였다. 선별된 균주의 균체내에 있는 2개의 plasmid DNA를 분리하여 각각의 plasmid를 pTG 17-1, pTG 17-2로 명명하였으며 S. cerevisiae MC 16에서 형질전환이 가능한 pTG 17-2 DNA를 제한효소 EcoRI과 Pst I으로 restriction한 결과 EcoRI으로 처리한 경우는 7.3, 4.8, 2.4 kb인 3개의 분획으로 나타났으며 Pst I으로 처리한 경우는 linear로 14.5kb임을 알았으며 이로써 pTG 17-2 plasmid의 size가 약 14kb임을 알았다. 또한 E.coli균체내에서의 ampicillin sensitive로써 이 plasmid의 ampicillin resistance site가 결실되었음을 알았고 효모의 형진전환체로 부터의 $\alpha$-amylase는 균체외로 분비되지 않았고 효모균체내의 $\alpha$-amylase는 Somogyi-Nelson방법과 Agar diffusion 방법으로 확인하였다.