• 한국재료학회지
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• 제16권4호
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• pp.257-263
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• 2006

We have investigated the effect of silver added to Cu films on the microstructure evolution, resistivity, surface morphology, stress relaxation temperature, and adhesion properties of Cu(Ag) alloy thin films deposited on Mo glue layer upon annealing. In addition, pure Cu films deposited on Mo has been annealed and compared. The results show that the silver in Cu(Ag) thin films control the grain growth through the coarsening of its precipitates upon annealing at $300^{\circ}C{\sim}600^{\circ}C$ and the grain growth of Cu reveals the activation energy of 0.22 eV, approximately one third of activation energy for diffusion of Ag dopant along the grain boundaries in Cu matrix (0.75 eV). This indicates that the grain growth can be controlled by Ag diffusion along the grain boundaries. In addition, the grain growth can be a major contributor to the decreased resistivity of Cu(Ag) alloy thin films at the temperature of $300^{\circ}C{\sim}500^{\circ}C$, and decreases the resistivity of Cu(Ag) thin films to $1.96{\mu}{\Omega}-cm$ after annealing at $600^{\circ}C$. Furthermore, the addition of Ag increases the stress relaxation temperature of Cu(Ag) thin films, and thus leading to the enhanced resistance to the void formation, which starts at $300^{\circ}C$ in the pure Cu thin films. Moreover, Cu(Ag) thin films shows the increased adhesion properties, possibly resulting from the Ag segregating to the interface. Consequently, the Cu(Ag) thin films can be used as a metallization of advanced TFT-LCDs.

• 한국환경농학회지
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• 제25권2호
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• pp.109-117
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• 2006

Photoinhibition and photoprotection of PSII in the leaves of hot pepper (Capsicum annuum L.) grown in Hoagland solution and Tap water were compared. Though changes in the rates of $O_2$ evolution as a function of photon fluence rate (PFR) were comparable, the rates of respiration in the dark was 3 times higher in the Hoagland solution grown leaves than in the Tap-water grown ones. Compared to Hoagland solution grown plane, PSIIs of Tap water grown pepper leaves were more susceptible to photoinhibitory light treatment. In order to inactivate functional PSII to the same extents, Hoagland solution grown plants required almost 2-fold high light $(1600{\mu}molm^{-2}s^-)$ treatment than those of Tap water $(900{\mu}molm^{-2}s^-)$. Interestingly, the remaining fraction of PSII in Hoagland grown pepper was able to survive under prolonged illumination in the presence of lincomycin, which probably means that the growth condition of plant seemed to have an effect on the recovery of PSII from light stress. When PSII was severly photoinactivated at a chilling temperature, recovery was observed only if the residual functional PSII were not inhibited with DCMU, Nigericin and MV during recovery. In conclusion, PSIIs grown in the Hoagland solution was more resistant to excess light than in the Tap water grown one and the recovery of PSII from photodamage was more efficient in Hoagland grown pepper leaves than Tap water grown one, which means that the increased dark respiration may play a important role in the protection of PSII from photoinhibition by helping repair photosynthetic proteins (in particular, the D1 protein of PSII) degraded by photoinhibition.

• 암석학회지
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• 제6권1호
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• pp.45-51
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• 1997

중생대 시기의 조구조 운동은 중국 동부 서태평양지역의 구조 발달사에 중요한 역할을 한 운동이다. 연산지역은 중생대의 전형적인 구조가 형성, 노출된 곳이며 쥬라기-백악기에 발생한 연산운동의 명명지이다. 과거에는 이 지역 대부분의 구조들은 연산운동에 의해 형성된 것으로 일반적으로 인정되어 왔지만, 다수의 습곡들은 삼첩기 후반에 발생한 인지운동에 의해 형성되었고 동시에 많은 대다수 단층들을 형성한 강렬한 활동이 있었음이 최근의 종합적 연구에 의해 밝혀졌다. 인지 운동이 발생한 조구조의 동역학적 환경은, 중·한지괴(Sino-Korean Massif)가 북쪽으로 이동하면서 대체로 E-W방향인 흥안-몽골 습곡대에 부딛쳐 생성된 N-S 방향의 압축응력 체제하에서 닫침 습곡(그 중 일부는 역전 습곡)이 형성되었으며, 연산운동의 몇차례 변형이 비공축(non-coaxial)으로 중첩(surperposed)되었다. 연산지역에서 중생대의 단층활동의 주요한 특성으로 인지운동시기에는 압축응력 작용에 의한 드러스트(thrust)가 주로 형성되었고, 연산운동시기에는 압축전단응력에 의한 사교 드러스트(oblique-thrust)가 주로 형성되었다.

• 콘크리트학회지
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• 제7권5호
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• pp.172-178
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• 1995

콘크리트는 타설시부터 수많은 미세균열을 가지고 있으며, 이러한 미세균열등이 성장하고 전파되어 결국에는 콘크리트가 파괴된다. 이러한 일련의 과정을 손상이라 한다. 손상은 주로 2차 텐서로 표현되며 균열은 연속체적 현상으로 취급된다. 본 논문에서는 손상의 특성을 유효응력개념과 함께 등가탄성에너지법을 이용하여 나타내었으며, Helmholtz 자유에너지와 소산 포텐셜을 이용하여 손상모델의 손상전개와 구성방정식을 유도하였다. 구성방정식은 콘크리트의 탄성, 이방성 손상과 소성의 영향을 포함하도록 하였다. 두 가지 형태의 유효접선강성텐를 사용하였는데, 하나는 탄성-손상의 영향에 의한 것이며 다른 하나는 소성-손상의 영향에 의한 것이다. 모델을 검증하기 위하여 일축과 이축의 하중을 받는 콘크리트 요소에 대하여 유한요소해석을 하였으며 그 결과를 실험결과와 비교하였다.

• Molecules and Cells
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• 제46권6호
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• pp.374-386
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• 2023

Thermal stress induces dynamic changes in nuclear proteins and relevant physiology as a part of the heat shock response (HSR). However, how the nuclear HSR is fine-tuned for cellular homeostasis remains elusive. Here, we show that mitochondrial activity plays an important role in nuclear proteostasis and genome stability through two distinct HSR pathways. Mitochondrial ribosomal protein (MRP) depletion enhanced the nucleolar granule formation of HSP70 and ubiquitin during HSR while facilitating the recovery of damaged nuclear proteins and impaired nucleocytoplasmic transport. Treatment of the mitochondrial proton gradient uncoupler masked MRP-depletion effects, implicating oxidative phosphorylation in these nuclear HSRs. On the other hand, MRP depletion and a reactive oxygen species (ROS) scavenger non-additively decreased mitochondrial ROS generation during HSR, thereby protecting the nuclear genome from DNA damage. These results suggest that suboptimal mitochondrial activity sustains nuclear homeostasis under cellular stress, providing plausible evidence for optimal endosymbiotic evolution via mitochondria-to-nuclear communication.

• 한국지반공학회논문집
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• 제27권10호
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• pp.81-92
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• 2011

팽윤성 점토의 전단강도 및 유변학적 특성은 점토입자의 크기, 양이온 교환능력, 점토광물학적 조성과 형상 등에 영향을 받는다. 본 연구는 고운 분말가루의 와이오밍(Wyoming) 벤토나이트에 대해 염화나트륨 0g/L 와 30g/L 농도로 24시간 수화시킨 후 염분농도에 따른 물성-강도특성 및 유변학적 특성변화를 살펴봄으로써, 유변학적 특성, 유변화적 모델들의 적용성 및 흙 입자의 구조변화에 따른 항복응력-점도와의 상관관계를 설명하고자 한다. 실험결과에 따르면, 팽윤성 점토는 전단담화(shear thinning)와 항복응력과 소성점도로 표현가능한 Bingham 유체 거동을 보이는 것으로 조사되었다. 염분농도가 낮고 함수비가 높아질수록 벤토나이트는 완전소성거동에 가깝게 나타나며, 전단변형률속도에 따른 변화의 폭이 미미한 것으로 조사되었다. 반면, 염분농도가 높아질수록 전형적인 전단담화거동을 보이며, 전단변형률속도를 증가시킬수록 염분농도에 따른 벤토나이트의 전단강도의 차이는 커진다. S=0g/L에 대해 Carreau, Herschel-Bulkley 및 멱수법칙 모델이, S=30g/L에 대해서는 이중선형, Herschel-Bulkley 및 멱수법칙 모델 등이 흐름특성을 가장 잘 표현한다. 이것은 염분농도에 따른 흙 입자간 구조적 배열과 형상이 입자간 발생하는 인력인 능-능(EE), 능-면(EF), 및 면-면(FF) 구조를 변화시키고 역학적 특성에 영향을 미치기 때문이다.

• Journal of Microbiology and Biotechnology
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• 제28권3호
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• pp.473-481
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• 2018

Owing to its high protein secretion capacity, simple nutritional requirements, and GRAS (generally regarded as safe) status, Bacillus licheniformis is widely used as a host for the industrial production of enzymes, antibiotics, and peptides. However, as compared with its close relative Bacillus subtilis, little is known about the physiology and stress responses of B. licheniformis. To explore its temperature-stress metabolome, B. licheniformis strains ATCC 14580 and B186, with respective optimal growth temperatures of $42^{\circ}C$ and $50^{\circ}C$, were cultured at $42^{\circ}C$, $50^{\circ}C$, and $60^{\circ}C$ and their corresponding metabolic profiles were determined by gas chromatography/mass spectrometry and multivariate statistical analyses. It was found that with increased growth temperatures, the two B. licheniformis strains displayed elevated cellular levels of proline, glutamate, lysine, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid, and decreased levels of glutamine and octadecenoic acid. Regulation of amino acid and fatty acid metabolism is likely to be associated with the evolution of protective biochemical mechanisms of B. licheniformis. Our results will help to optimize the industrial use of B. licheniformis and other important Bacillus species.

• Journal of Microbiology and Biotechnology
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• 제30권9호
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• pp.1420-1429
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• 2020

Corynebacterium glutamicum, an important industrial strain, has a relatively slower reproduction rate. To acquire a growth-boosted C. glutamicum, a descendant strain was isolated from a continuous culture after 600 generations. The isolated descendant C. glutamicum, JH41 strain, was able to double 58% faster (t_d=1.15 h) than the parental type strain (PT, t_d=1.82 h). To understand the factors boosting reproduction, the transcriptomes of JH41 and PT strains were compared. The mRNAs involved in respiration and TCA cycle were upregulated. The intracellular ATP of the JH41 strain was 50% greater than the PT strain. The upregulation of NCgl1610 operon (a putative dyp-type heme peroxidase, a putative copper chaperone, and a putative copper importer) that presumed to role in the assembly and redox control of cytochrome c oxidase was found in the JH41 transcriptome. Plasmid-driven expression of the operon enabled the PT strain to double 19% faster (t_d=1.82 h) than its control (t_d=2.17 h) with 14% greater activity of cytochrome c oxidase and 27% greater intracellular ATP under the oxidative stress conditions. Upregulations of genes those might enhance translation fitness were also found in the JH41 transcriptome. Plasmid-driven expressions of NCgl0171 (encoding a cold-shock protein) and NCgl2435 (encoding a putative peptidyl-tRNA hydrolase) enabled the PT to double 22% and 32% faster than its control, respectively (empty vector: t_d=1.93 h, CspA: t_d=1.58 h, and Pth: t_d=1.44 h). Based on the results, the factors boosting growth rate in C. gluctamicum were further discussed in the viewpoints of cellular energy state, oxidative stress management, and translation.

• Computers and Concrete
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• 제33권5호
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• pp.605-619
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• 2024

The increase of reclaimed asphalt pavement (RAP) content in recycled asphalt concrete (RAC) is accompanied by the degradation of low-temperature cracking resistance, which has become an obstacle to the development of RAC. This paper aims to reveal the meso-scale mechanisms of the low-temperature fracture behavior of RAC and provide a theoretical basis for the economical recycling of RAP. For this purpose, micromechanical heterogeneous peridynamic model of RAC was established and validated by comparing three-point bending (TPB) test results against corresponding numerical simulation results of RAC with 50% RAP content. Furthermore, the models with different aggregate shapes (i.e., average aggregates circularity (${\bar{C_r}}=1.00$, 0.75, and 0.50) and RAP content (i.e., 0%, 15%, 30%, 50%, 75%, and 100%) were constructed to investigate the effect of aggregate shape and RAP content on the low-temperature cracking resistance. The results show that peridynamic models can accurately simulate the low-temperature fracture behavior of RAC, with only 2.9% and 13.9% differences from the TPB test in flexural strength and failure strain, respectively. On the meso-scale, the damage in the RAC is mainly controlled by horizontal tensile stress and the stress concentration appears in the interface transition zone (ITZ). Aggregate shape has a significant effect on the low-temperature fracture resistance, i.e., higher aggregate circularity leads to better low-temperature performance. The large number of microcracks generated during the damage evolution process for the peridynamic model with circular aggregates contributes to slowing down the fracture, whereas the severe stress concentration at the corners leads to the fracture of the aggregates with low circularity under lower stress levels. The effect of RAP content below 30% or above 50% is not significant, but a substantial reduction (16.9% in flexural strength and 16.4% in failure strain) is observed between the RAP content of 30% and 50%. This reduction is mainly attributed to the fact that the damage in the ITZ region transfers significantly to the aggregates, especially the RAP aggregates, when the RAP content ranges from 30% to 50%.

• 환경생물
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• 제26권4호
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• pp.377-384
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• 2008

A cell is the product of a long period of evolution and can be represented as an optimized system (homeostasis). Stimuli from the outside environment are received by sensory apparatus on the surface of the cell and transferred through complicated pathways and eventually regulate gene expression. These signals affect cell physiology, growth, and development, and the interaction among genes in the signal transduction pathway is a critical part of the regulation. In this study, the interactions of deletion mutants and overexpression of the extracopies of the genes were used to understand their relationships to each other. Also, green fluorescent protein (GFP reporter gene) was fused to the regulatory genes to elucidate their interactions. Cooverexpression of the two genes in extracopy plasmids suggested that patS acts at the downstream of hetR in the regulatory network. The experiments using gfp fusion in different genetic background cells also indicated the epistasis relationships between the two genes. A model describing the regulatory network that controls cell development is presented.