• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.88.1-88.1
• /
• 2012

Silicon nanowires (SiNWs), due to their unusual quantum-confinement effects that lead to superior electrical and optical properties compared to those of the bulk silicon, have been widely researched as a potential building block in a variety of novel electronic devices. The conventional means for the synthesis of SiNWs has been the vapor-liquid-solid method using chemical vapor deposition; however, this method is time consuming, environmentally unfriendly, and do not support vertical growth. As an alternate, the electroless etching method has been proposed, which uses metal catalysts contained in aqueous hydrofluoric acids (HF) for vertically etching the bulk silicon substrate. This new method can support large-area growth in a short time, and vertically aligned SiNWs with high aspect ratio can be readily synthesized with excellent reproducibility. Nonetheless, there still are rooms for improvement such as the poor surface characteristics that lead to degradation in electrical performance, and non-uniformity of the diameter and shapes of the synthesized SiNWs. Here, we report a facile method of SiNWs synthesis having uniform sizes, diameters, and shapes, which may be other than just cylindrical shapes using a modified nanosphere lithography technique. The diameters of the polystyrene nanospheres can be adjustable through varying the time of O2 plasma treatment, which serve as a mask template for metal deposition on a silicon substrate. After the removal of the nanospheres, SiNWs having the exact same shape as the mask are synthesized using wet etching technique in a solution of HF, hydrogen peroxide, and deionized water. Different electrical and optical characteristics were obtained according to the shapes and sizes of the SiNWs, which implies that they can serve specific purposes according to their types.

• The Journal of Korean Medicine
• /
• v.24 no.3
• /
• pp.72-83
• /
• 2003

Objective : The goal of the present study was to investigate the protective effect of Gamiheechum-tang (Jiaweixiqian-tang; GHCT) on brain tissue damage from chemical or ischemic insults. Methods : Levels of cultured cortical neuron death caused by toxic chemicals were measured by LDH release assay. Neuroprotective effects of GHCT on brain tissues were examined in vivo by ischemic model of middle cerebral artery (MCA) occlusion. Results : Animal groups treated with GBCT showed significantly decreased hypertension, and reduced levels of aldosterone, dopamine, and epinephrine in the plasma. GHCT treatments ($l0-200\mu\textrm{g}/ml$) significantly decreased cultured cortical neuron death mediated by AMPA, kainate, BSO, or Fe2+ when measured by LDH release assay. Yet, cell death mediated by NMDA was effectively protected by GHCT at the highest concentration examined ($200\mu\textrm{g}/ml$). In the in vivo experiment examining brain damage by MCA occlusion, affected brain areas by ischemic damage and edema were significantly less in animal groups administered with GHCT compared to the non-treated control group. Neurological examinations of forelimbs and hindlimbs showed that GHCT treatment improved animals' recovery from ischemic injury. Moreover, the extent of injury in cortical and hippocampal pyramidal neurons in ischemic rats was much reduced by GHCT, whose morphological features were similarly observed in non-ischemic animals. Conclusion : The present data suggest that GBCT may play an important role in protecting brain tissues from chemical or ischemic injuries.

• The Korea Journal of Herbology
• /
• v.26 no.3
• /
• pp.47-56
• /
• 2011

Objectives : This study investigated whether the water extract of Spatholobi Caulis (SCE) has the ability to protect hepatocyte against oxidative stress induced by tert-butylhydroperoxide (tBHP) in vitro and $CCl_4$ in vivo. Methods : In vitro, HepG2 cells pre-treated with Spatholobi Caulis water extract (1, 3, 10, $30{\mu}g$/ml) for 12h and further incubated with tBHP ($100{\mu}M$) for the next 12h. Cell viability was assessed by MTT assay. In vivo, rats were orally administrated with the aqueous extract of Spatholobi Caulis (SCE; 50, 100 mg/kg) for 4 days and then, injected with $CCl_4$ 1 mg/kg body weight to induce acute liver damage. Results : Treatment with SCE inhibited cell death induced by tBHP, as evidenced by alterations in the levels of the proteins associated with apoptosis:SCE prevented a decrease in $Bcl_2$, and cleavage of poly(ADP-ribose)polymerase and pro-caspase-3. Moreover, SCE inhibited the ability of tBHP to generate $H_2O_2$ production, thereby restoring GSH content. Moreover, SCE treatments in rats effectively decreased liver injuries induced by a single dose of $CCl_4$, as evidenced by decreases in hepatic degeneration and inflammation as well as plasma alanine aminotransferase and lactate dehydrogenase activities. Consistently, treatments of SCE also protected liver in rats stimulated by $CCl_4$, as indicated by restoration GSH and prevention of MDA in the liver. Conclusions : SCE has the ability 1) to protect hepatocyte against oxidative stress induced by tBHP and 2) to prevent $CCl_4$-inducible acute liver toxicity. Present findings may be informative not only in elucidating the pharmacological mechanism of Spatholobi Caulis, but in determining its potential application for oxidative cellular damage in the liver.

• Korean Journal of Materials Research
• /
• v.19 no.8
• /
• pp.437-442
• /
• 2009

This paper describes an improved strategy for controlling the adhesion force using both the antiadhesion and adhesion layers for a successful large-area transfer process. An MPTMS (3-mercaptopropyltrimethoxysilane) monolayer as an adhesion layer for Au/Pd thin films was deposited on Si substrates by vapor self assembly monolayer (VSAM) method. Contact angle, surface energy, film thickness, friction force, and roughness were considered for finding the optimized conditions. The sputtered Au/Pd ($\sim$17 nm) layer on the PDMS stamp without the anti-adhesion layer showed poor transfer results due to the high adhesion between sputtered Au/Pd and PDMS. In order to reduce the adhesion between Au/Pd and PDMS, an anti-adhesion monolayer was coated on the PDMS stamp using FOTS (perfluorooctyltrichlorosilane) after $O_2$ plasma treatment. The transfer process with the anti-adhesion layer gave good transfer results over a large area (20 mm $\times$ 20 mm) without pattern loss or distortion. To investigate the applied pressure effect, the PDMS stamp was sandwiched after 90$^{\circ}$ rotation on the MPTMS-coated patterned Si substrate with 1-${\mu}m$ depth. The sputtered Au/Pd was transferred onto the contact area, making square metal patterns on the top of the patterned Si structures. Applying low pressure helped to remove voids and to make conformal contact; however, high pressure yielded irregular transfer results due to PDMS stamp deformation. One of key parameters to success of this transfer process is the controllability of the adhesion force between the stamp and the target substrate. This technique offers high reliability during the transfer process, which suggests a potential building method for future functional structures.

• Korean Journal of Pharmacognosy
• /
• v.34 no.3 s.134
• /
• pp.250-255
• /
• 2003

To develop Allium victorialis var. platyphyllum (Liliaceae) for an available functional food, pharmacological experiments on the extracts of this plant were undertaken in the rat treated with streptozotocin, poloxamer-407 and $CCl_4$. The two MeOH extracts were obtained from the leaves and the bulbs, respectively. The three agents, streptozotocin, poloxamer-407 and $CCl_4$, were treated to induce diabetes mellitus, hyperlipidemia and hepatic injury, respectively. Treatment with the leaf extract lowered blood glucose by 24.9% at 200 mg/kg (p.o.) in the STZ-treated rat and prohibited the increase of body weight, water consumption and food intake. This exσact also significantly decreased not only thε plasma cholesterol and triglyceride in the poloxamer-407-treated rat by 35.3% but also serum ALT by 49.0%. The potency was found by overall estimation on the experimental results as followings: 200 mg/kg leaf extract> 200 mg/kg bulb extract> 100 mg/kg leaf exσact> 100 mg/kg bulb extract. These results suggested that this plant might have the availability for a functional food. It was also suggested that the leaves are more effective than the bulbs for the functional vegetable, especially in hyperlipidemia and hepatic injury.

• Journal of Ginseng Research
• /
• v.19 no.1
• /
• pp.31-38
• /
• 1995

Antioxidant effect of Korean ginseng (Panax ginseng C.A. Meyer) was investigated in rats. Long-term administration of ginseng water extract protected the activity of liver cytosotic SOD, catalase and glutathione peroxidase from being significantly decreased with advancing age (p<0.05). It was more effective toward glutathione peroxidase than other antioxidant enzymes. However, the level of sulfhydryl compounds and its related enzymes such as glutathione reductase and glutathione-5-transferase was not significantly changed by the administration of ginseng. Liver microsomal formation of reactive oxygen species such as superoxide and hydrogen peroxide did not show a significant difference between two groups although it was slightly decreased with age, but lipid peroxidizability of microsomal membrane induced by a prooxidant was slightly lower in ginseng-treated rats. Interestingly, antioxidant capacity of plasma from ginseng treated rats on autooxidation of ok-brain homogenates was much higher than that of normal ones. However, resistance of RBC membrane against oxidative stress showed a similar tendency. The content of serum TBA reactive substances lowered consistently in the rats treated with r ginseng at all corresponding age and a significant difference between two groups was found at 24 months of age (p<0.05). Ginseng extract protected lipid peroxidation in brain and liver. This protection was more effective in the stressed rats imposed by immobilization than normal ones. In conclusion, ginseng water extract protected the age related deterioration of major antioxidant enzymes, and this effect was more striking with increasing duration of treatment. This comprehensive antioxidant action of ginseng seems to be bra certain action of ginseng other than a direct antioxidant action, which might be a long term normalizing effect through the harmony of various components.

• Journal of Periodontal and Implant Science
• /
• v.53 no.1
• /
• pp.2-19
• /
• 2023

Purpose: Surgical techniques in orthodontics have received widespread attention in recent years. Meanwhile, biomaterials with high molecular content have been introduced, such as platelet concentrates (PCs), which may accelerate orthodontic tooth movement (OTM) and reduce periodontal damage. The present systematic review aimed to answer the following PICO question: "In patients in whom orthodontic surgical techniques are performed (P), what is the effectiveness of using PCs over the surgical site (I) when compared to not placing PCs (C) to achieve faster tooth movement (O)?" Methods: A search was performed in 6 databases. The criteria employed were those described in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses declaration. The present review included studies with a control group that provided information about the influence of PCs on the rate of OTM. Results: The electronic search identified 10 studies that met the established criteria. Conclusions: The included studies were very diverse, making it difficult to draw convincing conclusions. However, a tendency was observed for OTM to be accelerated when PCs were used as an adjuvant for canine distalization after premolar extraction when distalization was started in the same session. Likewise, studies seem to indicate an association between PC injection and the amount of canine retraction. However, it is not possible to affirm that the use of PCs in corticotomy shortens the overall treatment time, as this question has not been studied adequately.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.9
• /
• pp.1208-1214
• /
• 2011

Caffeine, a psychoactive stimulant, has been implicated in the modulation of learning and memory functions due to its action as a non-selective adenosine receptors antagonist. On the contrary, some side effects of caffeine have been reported, such as an increased energy loss and metabolic rate, decrease DNA synthesis in the spleen, and increased oxidative damage to exerted on LDL particles. Therefore, the aim of this study was to develop a safe stimulant from natural plants mixture (Aralia elata, Acori graminei Rhizoma, Chrysanthemum, Dandleion, Guarana, Shepherd's purse) that can be used as a substitute for caffeine. Thirty SD rats were divided into three groups; control group, caffeine group (15.0 mg/kg, i.p.), and natural plants mixture group (NP, 1 mL/kg, p.o.). The effect of NP extract on stimulant activity was evaluated with open-field test (OFT) and plus maze test for measurement of behavioral profiles. Plasma lipid profiles, lipid peroxidation in LDL (conjugated dienes), total antioxidant capacity (TRAP) and DNA damage in white blood, liver, and brain cells were measured. In the OFT, immobility time was increased significantly by acute (once) and chronic (3 weeks) supplementation of NP and showed a similar effect to caffeine treatment. Three weeks of caffeine treatment caused plasma lipid peroxidation and DNA damage in liver cells, whereas there were no changes in the NP group. NP group showed a higher plasma HDL cholesterol concentration compared to the caffeine group. The results indicate that the natural plants mixture had a stimulant effect without inducing oxidative stress.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2001.11a
• /
• pp.28-28
• /
• 2001

$TiCl_44,{\;}AICl_3,{\;}H_2,{\;}Ar,{\;}NH_3$ 기체를 사용하여 플라즈마 화학 증착법으로 $(Ti_{1-x}AI_x)N$ 피막을 증착한 후 진공열처리 실험을 통해 열처리 전후에 나타나는 피막의 가계적 특성 변화 및 상변화 양상에 대해 연구하였다. 기판으로는 M2 고속도강과 알루미나(${\alpha}-Al_2O_3$)를 사용하였으며, 열처리 실험은 진공 열처리로를 이용하여 $800$ ~ $1100^{\circ}C$ 에서 진행하였다. M2 고속도강 위에 증착한 $(Ti_{1-x}AI_x)N$ 피막은 모두 (200) 우선 방위를 갖고 있었으며, AI의 함량이 높아짐에 따라 입자의 크기가 미세해져 $(Ti_{0.2}AI_{0.8})N$ 의 경우 수 nm의 업자들로 이루어져 있었다. 열처리 시간을 일정하게 하고, 그 온도를 증가시킬 경우 비교적 낮은 온도 영역($~900^{\circ}C$)에서는 경도 증가를 나타내지만, 열처리가 더욱 진행됨에 따라 다시 경도가 감소하는 양상을 나타내었으며, 열처리 온도를 일정하게 하고 열처리 시간을 변화 시킬 경우에도 초기에 경도가 증가하다가 열처리가 진행됨에 따라 경도가 다시 감소하는 현상을 관찰 하였다. 이때 경도증가 정도는 Al 함량이 높을 수록 뚜렷하고 오래 지속되었으며, $(Ti_{0.2}AI_{0.8})N$ 피막의 경우 열처리 전 $2000HK_{0.01}$에서 열처리 후 $4500HK_{0.01}$로, 매우 큰 경도 증가를 나타내었다. 이와 같은 열처리 전후의 기계적 특성 변화는 준 안정상의 $(Ti_{1-x}AI_{x})N$ 피막에서, 열처리가 진행됨에 따라 미세한 AlN 업자가 석출되면서 나타나는 현상으로, 고분해능 전자현미경(HRTEM) 분석을 통해 경도가 증가한 시편의 경우 석출상의 크기가 5nm 이하로 매우 작고 대체로 기지와 연속적인 계면을 형성하나, 열처리가 진행될수록 석 출상의 크기가 커지고 임계크기 이상에 이르면 연속적인 계면은 거의 발견되지 않고, 대부 분 불연속적이고 확연한 계면을 형성함을 관찰 할 수 있었다. 알루미나(${\alpha}-Al_2O_3$) 기판 위에 증착한 $(Ti_{1-x}AI_{x})N$ 피막은 마찬가지로 (200) 우선 방위를 나타내었으나, 그 입자의 크기가 수십 nm로 고속도강위에 증착한 피막에 비해 상당히 크게 형성되었다. 또한 열처리 후에 AIN의 석출이 진행됨에도 불구하고 경도 증가는 나타나지 않고, 열처리가 진행됨에 따라 경도가 감소하는 양상만을 나타내었다. 결국 $(Ti_{1-x}AI_{x})N$ 피막이 열처리 전후에 보아는 기계적 특성의 변화 양상은 열역학적으로 안정한 Wurzite-AlN의 석출에 따른 것으로 AlN 석출상의 크기에 의존하며, 또한 이러한 영향은 $(Ti_{1-x}AI_{x})N$ 피막에 존재하는 AI의 함량이 높고, 초기에 증착된 막의 업자 크기가 작을 수록 클 것으로 여겨진다.

• The Journal of Internal Korean Medicine
• /
• v.32 no.3
• /
• pp.345-360
• /
• 2011

Objectives : This study was examined to investigate the effects of Cheonmagudeng-um gagam (CGG) extract on spontaneous hypertension. Methods : For the study of CGG, we divided rats into three groups. The normal group was Wister Kyoto rats (WKY). The control group was spontaneously hypertensive rats (SHR). The treatment group was SHR which were administered CGG extract (SHR-CGG). SHR-CGG were orally administered CGG extract that was diluted in distilled water at the various concentrations for 4 weeks (234.5 mg/kg) and SHR were orally administered the same dosage of plain distilled water as SHR-CGG. Then we measured anti-oxygen effects, ACE inhibitory activity, weight of heart and kidney, blood pressure, heart rate, plasma aldosterone, electrolyte, creatinine, uric acid, BUN, and observed the cortex of the cardiac muscle, kidney, and adrenal gland. Results : CGG increased DPPH scavenging activity and SOD similar activity depending on the concentration. CGG significantly decreased ROS, TNF-${\alpha}$, IL-6, IL-$1{\beta}$, heart weight, blood pressure, heart rate, aldosterone, and BUN in SHR. CGG increased ACE inhibition activity depending on the concentration. CGG inhibited the heart, kidney and adrenal gland tissue injury that is caused by hypertension. Conclusions : These results suggest that CGG is effective in treatment and prevention of hypertension.