• The Korean Journal of Ceramics
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• 제2권2호
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• pp.95-101
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• 1996

Variations of the leakage current behaviors and interface potential barrier $({\Phi}_B)$ of rf-sputter deposited (Ba, Sr)$TiO_3$ (BST) thin films with thicknesses ranging from 20 nm to 150nm are investigated as a function of the thickness and bias voltages. The top and bottom electrodes are dc-sputter-deposited Pt films. ${\Phi}_B$ critically depends on the BST film deposition temperature, postannealing atmosphere and time after the annealing. The postannealing under $N_2$ atmosphere results in a high interface potential barrier height and low leakage current. Maintaining the BST capacitor in air for a long time reduces the ${\Phi}_B$ from about 2.4 eV to 1.6 eV due to the oxidation. ${\Phi}_B$ is not so dependent on the film thickness in this experimental range. The leakage conduction mechanism is very dependent on the BST film thickness; the 20 nm thick film shows tunneling current, 30 and 40 nm thick films show Shottky emission current.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권5호
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• pp.385-390
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• 1999

Surface corona discharge characteristics of a dc corona charged ferroelectric pellet barrier have been investigated experimentally. Electric charges stored on the surfaces of the ferroelectric pellets by a dc corona discharge provide partial electric fields on the surfaces of the ferroelectric pellets, which could generate surface corona discharges on the ferroelectric pellets. This system utilizes both the surface discharges on the ferroelectric pellet barrier and the corona discharge between corona tip and mesh electrode. Positive and negative dc voltages were applied to the tip to generate partial discharges, and corona currents were estimated to investigate the buildup charge on ferroelectric pellets as a function of the applied time and the charge relaxation time constants of ferroelectric pellets. As a result, in the case of the negative corona discharge with the ferroelectric pellet barrier, the mean corona current and ozone generation increase greatly, and the surface discharges on the ferroelectric pellets can be fenerated efficiently. It is also found that, charge relaxation time, dielectric constants offerroelectric pellets, polarity of applied voltage and applied time affected to the surface discharges among the ferroelectric pellets.

• 한국전기전자재료학회논문지
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• 제24권4호
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• pp.271-275
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• 2011

In this paper, thermal stability of palladium germanide (Pd germanide) is analyzed for high performance Schottky barrier germanium metal oxide semiconductor field effect transistors (SB Ge-MOSFETs). Pd germanide Schottky barrier diodes were fabricated on n-type Ge-on-Si substrates and the formed Pd germanide shows thermal immunity up to $450^{\circ}C$. The barrier height of Pd germanide is also characterized using two methods. It is shown that Pd germanide contact has electron Schottky barrier height of 0.569~0.631 eV and work function of 4.699~4.761 eV, respectively. Pd germanide is promising for the nanoscale Schottky barrier Ge channel MOSFETs.

• Journal of Ginseng Research
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• 제46권1호
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• pp.115-125
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• 2022

Background: Ginsenosides (GS) have potential value as cosmetic additives for prevention of skin photoaging. However, their protective mechanisms against skin barrier damage and their active monomeric constituents are unknown. Methods: GS monomer types and their relative proportions were identified. A UVB-irradiated BALB/c hairless mouse model was used to assess protective effects of GS components on skin epidermal thickness and transepidermal water loss (TEWL). Skin barrier function, reflected by filaggrin (FLG), involucrin (IVL), claudin-1 (Cldn-1), and aquaporin 3 (AQP3) levels and MAPK phosphorylation patterns, were analyzed in UVB-irradiated hairless mice or HaCaT cells. Results: Total GS monomeric content detected by UPLC was 85.45% and was largely attributed to 17 main monomers that included Re (16.73%), Rd (13.36%), and Rg1 (13.38%). In hairless mice, GS ameliorated UVB-induced epidermal barrier dysfunction manifesting as increased epidermal thickness, increased TEWL, and decreased stratum corneum water content without weight change. Furthermore, GS treatment of UVB-irradiated mice restored protein expression levels and epidermal tissue distributions of FLG, IVL, Cldn-1, and AQP3, with consistent mRNA and protein expression results obtained in UVB-irradiated HaCaT cells (except for unchanging Cldn-1 expression). Mechanistically, GS inhibited JNK, p38, and ERK phosphorylation in UVB-irradiated HaCaT cells, with a mixture of Rg2, Rg3, Rk3, F2, Rd, and Rb3 providing the same protective MAPK pathway inhibition-associated upregulation of IVL and AQP3 expression as provided by intact GS treatment. Conclusion: GS protection against UVB-irradiated skin barrier damage depends on activities of six ginsenoside monomeric constituents that inhibit the MAPK signaling pathway.

• Journal of Microbiology and Biotechnology
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• 제32권7호
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• pp.825-834
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• 2022

Inflammatory bowel disease (IBD) is a global disease that is in increasing incidence. The gut, which contains the largest amount of lymphoid tissue in the human body, as well as a wide range of nervous system components, is integral in ensuring intestinal homeostasis and function. By interacting with gut microbiota, immune cells, and the enteric nervous system, the intestinal barrier, which is a solid barrier, protects the intestinal tract from the external environment, thereby maintaining homeostasis throughout the body. Destruction of the intestinal barrier is referred to as developing a "leaky gut," which causes a series of changes relating to the occurrence of IBD. Changes in the interactions between the intestinal barrier and gut microbiota are particularly crucial in the development of IBD. Exploring the leaky gut and its interaction with the gut microbiota, immune cells, and the neuroimmune system may help further explain the pathogenesis of IBD and provide potential therapeutic methods for future use.

• 한국임상수의학회지
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• 제25권5호
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• pp.330-339
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• 2008

세라마이드, 콜레스테롤, 자유지방산은 각질세포간 주요 지질로써 피부장벽의 생성과 유지에 있어 중요한 역할을 담당한다. 그러나, 개에서 각질세포간 지질에 대한 역할은 거의 알려져 있지 않다. 본 연구는 개에서 1.25% sodium lauryl sulphate (SLS)에 의한 피부 장벽손상 유발후 2% 세라마이드, 2%콜레스테롤, 2% 리놀레익산과 이들 세가지 지질의 혼합제 (혼합제)의 장벽손상 복구를 평가하고자 실시하였다. 피부장벽기능은 표피경유수분소실(TEWL), 피부 수화도, 피부 산도, 피부 두께 측정을 통하여 평가하였고 최종적으로 조직학적 분석과 투과 전자 현미경 (TEM)을 통하여 피부 장벽구조를 평가하였다. SLS는 개의 피부에 효과적으로 피부장벽 손상을 유발하였다. 표피경유수분소실은 세라마이드와 혼합제 적용부위에서 계면활성제 및 대조군과 비교하여 유의적인 감소를 나타내었다 (p<0.05, p<0.01). 표피경유수분소실은 12일째에 모든 지질 적용군에서 유의적으로 감소하였으나 특히 세라마이드와 혼합제에서 콜레스테롤과 리놀레익산보다 유의적으로 감소하였다 (p<0.01). 실험 기간 동안, 피부 수화도는 세라마이드와 혼합제에서 유의적 증가를 보였다 (p<0.01). 조직학적 분석에서도 각각의 지질들은 피부손상을 회복시켰다. 특히 세라마이드와 혼합제의 효과가 탁월하였고 각질층의 두께도 대조군에 비해 유의적으로 증가되었다. 피부 산도는 세라마이드, 리놀레익산, 혼합제에서 유의적으로 감소하였다 (p<0.05). 따라서 세라마이드와 혼합제의 국소적용은 계면활성제에 의한 피부 장벽 손상에 효과가 탁월함을 확인하였으며 아토피와 같은 염증성 피부염과 외부 자극에 의한 피부 장벽 손상시에도 세라마이드 또는 혼합제의 병용이 효과적일 것으로 사료된다.

• 대한화장품학회지
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• 제29권2호
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• pp.205-232
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• 2003

Ursolic acid (UA) and Oleanolic acid (ONA), known as urson, micromerol and malol, are pentacyclic triterpenoid compounds which naturally occur in a large number of vegetarian foods, medicinal herbs, and plants. They may occur in their free acid form or as aglycones for triterpenoid saponins, which are comprised of a triterpenoid aglycone, linked to one or more sugar moieties. Therefore UA and ONA are similar in pharmacological activity. Lately scientific research, which led to the identification of UA and ONA, revealed that several pharmacological effects, such as antitumor, hepato-protective, anti-inflammatory, anticarcinogenic, antimicrobial, and anti-hyperlipidemic could be attributed to UA and ONA. Here, we introduced the effect of UA and ONA on acutely barrier disrupted and normal hairless mouse skin. To evaluate the effects of UA and ONA on epidermal permeability barrier recovery, both flanks of 8-12 week-old hairless mice were topically treated with either 0.01-0.1 mg/ml UA or 0.1-1 mg/ml ONA after tape stripping, and TEWL (Transepidermal water loss) was measured . The recovery rate increased in those UA or ONA treated groups (0.1 mg/ml UA and 0.5 mg/ml ONA) at 6 h more than $20\%$ compared to vehicle treated group (p<0.05). Here, we introduced the effects of UA and ONA on acute barrier disruption and normal epidermal permeability barrier function. For verifying the effects of UA and ONA on normal epidermal barrier, hydration and TEWL were measured for 1 and 3 weeks after UA and ONA applications (2mg/ml per day). We also investigated the features of epidermis and dermis using electron microscopy (EM) and light microscopy (LM). Both samples increased hydration compared to vehicle group from f week without TEWL alteration (p<0.005). EM examination using RuO4 and OsO4 fixation revealed that secretion and numbers of lamellar bodies and complete formation of lipid bilayers were most prominent $(ONA{\geq}UA>Vehicle)$. LM finding showed that thickness of stratum corneum (SC) was slightly increased and especially epidermal thickening and flattening was observed (UA>ONA>Veh). We also observed that UA and ONA stimulate epidermal keratinocyte differentiation via $PPAR\;\alpha$. Protein expression of involucrin, loricrin, and filaggrin increased at least 2 and 3 fold in HaCaT cells treated with either $ONA\;(10{\mu}M)$ or UA $(10{\mu}M)$ for 24h respectively. This result suggested that the UA and ONA can improve epidermal permeability barrier function and induce the epidermal keratinocyte differentiation via $PPAR\;{\alpha}$. Using Masson-trichrome and elastic fiber staining, we observed collagen thickening and elastic fiber elongation by UA and ONA treatments. In vitro results of collagen and elastin synthesis and elastase inhibitory activity measurements were also confirmed in vivo findings. These data suggested that the effects of UA and ONA related to not only epidermal permeability barrier functions but also dermal collagen and elastic fiber synthesis. Taken together, UA and ONA can be relevant candidates to improve epidermal and dermal functions and pertinent agents for cosmeseutical applications.

• 대한화장품학회지
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• 제46권1호
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• pp.73-80
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• 2020

심리적 스트레스는 피부의 생리적 상태에 영향을 미치고 다양한 피부 질환을 일으킬 수 있다. 스트레스 호르몬인 코티솔은 섬유질, 케라틴세포, 멜라노사이트와 같은 다양한 피부세포에 의해 분비된다. 밀착연접(tight junction, TJ) 은 포유류 피부의 과립증에서 장벽을 형성하는 세포 접합부위이다. TJ은 다른 피부 장벽기능에도 영향을 미칠 수 있으며 화학, 미생물 또는 면역학적 피부장벽에게 영향을 받는다. 스트레스로 인한 피부 장벽 손상에 관한 보고는 있지만 사람피부에서 코티솔이 TJ을 조절한다는 보고는 없다. 스트레스 호르몬 코티솔이 TJ을 조절하는 기능을 확인하기 위해 각질형성세포에 코티솔을 처리하였다. 코티솔은 TJ 구성 성분의 유전자 발현과 구조를 조절하여 피부 장벽 기능을 손상시켰다. 또한 코티솔은 인공피부 모델에서 과립층 형성을 억제하였다. 이러한 실험결과를 통해 스트레스 호르몬 코티솔이 TJ를 조절함으로써 피부 장벽 기능에 손상을 일으키는 것을 확인할 수 있었다.

• BMB Reports
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• 제39권4호
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• pp.339-345
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• 2006

The blood-neural barrier (BNB), including blood-brain barrier (BBB) and blood-retinal barrier (BRB), is an endothelial barrier constructed by an extensive network of endothelial cells, astrocytes and neurons to form functional 'neurovascular units', which has an important role in maintaining a precisely regulated microenvironment for reliable neuronal activity. Although failure of the BNB may be a precipitating event or a consequence, the breakdown of BNB is closely related with the development and progression of CNS diseases. Therefore, BNB is most essential in the regulation of microenvironment of the CNS. The BNB is a selective diffusion barrier characterized by tight junctions between endothelial cells, lack of fenestrations, and specific BNB transporters. The BNB have been shown to be astrocyte dependent, for it is formed by the CNS capillary endothelial cells, surrounded by astrocytic end-foot processes. Given the anatomical associations with endothelial cells, it could be supposed that astrocytes play a role in the development, maintenance, and breakdown of the BNB. Therefore, astrocytes-endothelial cells interaction influences the BNB in both physiological and pathological conditions. If we better understand mutual interactions between astrocytes and endothelial cells, in the near future, we could provide a critical solution to the BNB problems and create new opportunities for future success of treating CNS diseases. Here, we focused astrocyte-endothelial cell interaction in the formation and function of the BNB.

• 대한화장품학회지
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• 제46권3호
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• pp.307-317
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• 2020

피부 표피의 장벽 구조는 신체 내부의 수분 손실을 방지하고 외부의 이물질의 침입을 막는데 핵심적인 구조이고 각질세포와 세포간 지질로 구성된다. 이 때, 피부 장벽의 세포간 지질은 orthorhombic 구조로 패킹되어있을 때 가장 강한 구조를 가지고 있다. 그러나 다양한 외부 원인에 의해 손상되어 hexagonal 구조로 변화한다. 이런 물리적인 구조의 변화는 FT-IR을 이용하여 지질의 CH₂-CH₂ scissoring band의 시그널은 분석하여 비 침습적으로 분석 가능하다. 본 연구에서는 SDS를 Porcine skin에 처리하여 피부 장벽 손상모델을 구축하고 FT-IR signal을 분석하여 패킹구조의 변화 정도를 수치화 하였다. 이후 화장품 제형의 처리에 따라서 손상 모델의 장벽 회복 여부를 판단하였다. 이를 통하여 기존의 피부 장벽의 수분 증발량을 분석하는 간접적인 측정 방식을 보완할 수 있다. 또한, 피부 장벽 구조의 물리적인 변화를 직접적이고 효율적으로 분석하는 방식으로 활용 가능하여 다양한 소재의 기능 규명과 제형의 검증에 사용될 수 있다.