• KSBB Journal
• /
• 제29권4호
• /
• pp.278-284
• /
• 2014

We present microfluidic method to rapidly analyze the effect of temperature on the change of morphologies of Antarctic bacteria (Pseudoalteromonas sp., Shewanella vesiculosa, Shewanella sp., and Cellulophaga sp.). The microfluidic device is able to generate stable temperature gradient from 7 to$40^{\circ}C$ and dramatically reduce the number of experiments, experimental cost and labor, and amount of sample. Based on this approach, we found that specific bacteria transforming morphology into filament or elongated body strongly depends on cultivation temperature. Interestingly, we found that the morphologies of Pseudoalteromonas sp., Shewanella vesiculosa, Shewanella sp., and Cellulophaga sp. are elongated at below $25^{\circ}C$, above $20^{\circ}C$, above $15^{\circ}C$ and above $35^{\circ}C$, respectively. We envision the microfluidic device is a useful approach to analyze biological events with a high throughput manner.

• Journal of Microbiology and Biotechnology
• /
• 제19권11호
• /
• pp.1408-1414
• /
• 2009

The obtention of high yields of purified plasmid DNA is viewed as an essential issue to be considered towards efficient production of DNA vaccines and therapeutic plasmids. In this work, Escherichia coli $DH5\alpha$. bearing the pVAXI-LacZ plasmid was grown in a developed semi-defined medium at different temperatures and tryptone concentrations. Analysis of pDNA yields and E. coli morphology revealed that at higher temperatures (37 and $40^{\circ}C$), higher specific yields and E. coli filamentation were obtained. However, the best results were achieved when a lower tryptone concentration was used. This approach was shown to be a powerful tool to promote plasmid amplification, keeping the desirable plasmid structure, and favoring the attainment of quality. Our results suggest that by using tryptone alone as an amino acid source, pDNA amplification was improved and a specific yield of 20.43 mg pDNA/g dcw was achieved, proving that this strategy can improve pDNA yield even at a small scale.

• 한국정밀공학회지
• /
• 제23권5호
• /
• pp.190-196
• /
• 2006

Transparent materials are widely used in the fields of optic parts and bio industry. We have experiment to find out the characteristics of the micromachining inside transparent materials using femtosecond laser pulses. With its non-linear effects by very high peak intensity, filament (plasma channel) was formed by the cause of the self-focusing and the self-defocusing. Physical damage could be found when the intensity is high enough to give rise to the thermal stress or evaporation. At the vicinity of the power which makes the visible damage or modification, the structural modification occurs with the slow scanning speed. According to the polarization direction to the scanning direction, the filament quality is quite different. There is a good quality when the polarization direction is parallel to the scanning direction. For fine filament, we could suggest the conditions of the high numerical aperture lens, the short shift of focusing point, the low scanning speed and the low power below 20 mW. As the examples of optics parts, we fabricated the fresnel zone plate with the $225{\mu}m$ diameter and Y-bend optical wave guide with the $5{\mu}m$ width.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.477-478
• /
• 2006

Characteristics of InAs/GaAs quantum dot (QD) ridge laser diodes (LDs) are investigated for high-power $1.3\;{\mu}m$ applications. For QD ridge LDs with a $5-{\mu}m$-wide stripe and a 1-mm-long cavity, the emission wavelength of 1284.1 nm, the single-uncoated-facet CW output power as high as 90 mW, the external efficiency of 0.31 W/A and the threshold current density of $800\;mA/cm^2$ are obtained. The linewidth enhancement factor ($\alpha$-factor) is successfully measured to be between 0.4 and 0.6, which are about four times as small values with respect to conventional quantum well structure. It is possible that this result significantly reduce the filamentation of far-field profiles resulting in better beam quality for high power operation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.131-131
• /
• 2010

The power of semiconductor laser diodes has been limited primarily by the heating effects which occur at high optical intensities. The actual limiting event can take one of a number of forms such as. catastrophic optical damage or filamentation. A general approach to this problem is to design a heterostructure which creates a high powered output while maintaining low internal optical intensities. A graded index separate confinement heterostructure (GRIN-SCH) is one such structure that accomplishes the above task. Here, the active region is sandwiched between graded index layers where the index of refraction increases nearer to the active layer. This structure has been shown to yield a high efficiency due to the confinement of both the optical power and carriers, thereby reducing the optical intensity required to achieve higher powers. The optical confinement also reinforces the optical beam quality against high power effects. Quantum dots have long been a desirable option for laser diodes due to the enhanced optical properties associated with the zeroth dimensionality. In our work, we use PICS3D software created by Crosslight Software Inc. to simulate the performance of In0.67A10.33As/A10.2Ga0.8AsquantumdotsusedwithaGRIN-SCH. The simulation tools are used to optimize the GRIN-SCH structure for high efficiency and optical beam quality.

• 미생물학회지
• /
• 제54권1호
• /
• pp.1-8
• /
• 2018

원핵 세포는 핵양체 결합 단백질(NAP)로 알려진 다양한 히스톤 유사 단백질을 가지고 있다. 이들은 DNA의 AT-rich 서열에 결합하여, DNA 자체를 감싸거나, 구부리거나, 떨어져 있는 DNA 가닥을 연결시키는 다리 역할을 하여, 결국에는 원핵 생물의 유전자 발현을 조절한다. NAP는 특히 전사의 억제 기능을 가지고 있기 때문에, 유전자 발현 억제에 있어서 이들의 역할과, 구체적인 메커니즘을 밝히는 것을 매우 중요한 일이다. 본 논문에서는 잘 알려져 있는 NAP인 H-NS와 HU에 대하여 정리하였고, 특히 E. coli와 Salmonella Typhimurium에서 이들의 유전자 발현에 대한 기능을 요약하였다. H-NS는 이들의 올리고머화와 필라멘트 구조 형성을 통하여 Salmonella와 같은 사람에 감염하는 병원성 세균의 독성유전자 발현을 억제할 수 있고, 이런 기능을 수행하였을 때 다른 NAP와 함께 작용할 수 있다. 최근에 H-NS는 사람에게 typhoid fever와 systemic disease를 발생시키는 독성물질인, typhoid toxin의 발현 또한 조절할 수 있음이 밝혀졌다. Salmonella에서 HU 또한 독성 유전자뿐만 아니라, 이들의 생리적 기능에 중요한 유전자들의 발현을 조절할 수 있다. 따라서, H-NS와 HU와 같은 NAP들이 원핵 생물의 독성 유전자 발현의 분자적인 메커니즘을 밝히는데 중요한 요소임을 제시한다.