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        검색결과 9,514

        5961.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The bi-materials with Al-Mg alloy and its composites reinforced with SiC and particles were prepared by conventional powder metallurgy method. The A1-5 wt%Mg and composite mixtures were compacted under , and then the mixtures compacted under 400 MPa were sintered at for 5h. The obtained bi-materials with Al-Mg/SiCp composite showed the higher relative density than those with composite after compaction and sintering. Based on the results, the bi-materials compacted under 400 MPa and sintered at 873K for 5h were used for mechanical tests. In the composite side of bi-materials, the SiC particles were densely distributed compared to the particles. The bi-materials with Al-Mg/SiC composite showed the higher micro-hardness than those with composite. The mechanical properties were evaluated by the compressive test. The bi-materials revealed almost the same value of 0.2% proof stress with Al-Mg alloy. Their compressive strength was lower than that of Al-Mg alloy. Moreover, impact absorbed energy of bi-materials was smaller than that of composite. However, the bi-materials with Al-Mg/SiCp composite particularly showed almost similar impact absorbed energy to composite. From the observation of microstructure, it was deduced that the bi-materials was preferentially fractured through micro-interface between matrix and composite in the vicinity of macro-interface.
        4,000원
        5965.
        2007.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the effects of serratus anterior strengthening exercises on scapular position and Visual Analog Scale (VAS) pain measurements taken at the resting position in young adults with adducted scapular. The exercise program included stretching of the scapular retractor and strengthening of the serratus anterior muscle. We measured the distance from the midline of the thorax to the vertebral border of the scapular with a tape line (Superior Kibler), and the distance from the 7th cervical spinous process to the acromial angle with 3-dimension motion analysis system, to compare the resting scapular position before and after exercise. Fifteen subjects with adducted scapular were recruited to compare the resting scapular position and VAS. The distance from 7th cervical spine process to acromial angle of the scapular and VAS decreased significantly (p<.01) after exercise, while the distance from the midline of the thorax to vertebral border of the scapular increased (p<.05). The conclusion is that the serratus anterior exercise program altered the resting scapular position and decreased VAS.
        4,000원
        5966.
        2007.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To improve abdominal muscles strengthening, double straight leg lowering (DSLL) has been widely used in physical therapy, fitness program, and athletic program. The purpose of this study was to investigate the effects of the lumbar stabilization maneuver with a pressure biofeedback unit on the muscle activity of rectus abdominis (RA), external oblique (EO), and internal oblique (IO) during DSLL. Fourteen healthy young men were recruited from university population. The electromyography (EMG) activity was recorded from the RA, EO, and IO of both sides. The normalized EMG activity was compared using a paired t-test. The study showed that EMG activity in the RA, EO, and IO was significantly higher during DSLL with lumbar stabilization (DSLL-LS) compared to performed DSLL (p<.05). These results suggest that DSLL-LS is recommended as an effective method for strengthening exercise for the abdominal muscles.
        4,000원
        5972.
        2007.10 KCI 등재 구독 인증기관·개인회원 무료
        PDT is an established cancer treatment modality, This can be attri buted to the attractive basic concept of PDT; the combination 0 1' two therapeutic agents , a photosensiti zing drug and light, which are relatively harmless by themselves but combined ultimately cause more 0 1' less selective tumor destruction, The bacteri ochlorophyll - derivatived photosensitizer s are known to be s tabl e and highly effïcient, ln thí s study, we conducted a seríes of experiments to develope the light induced anticancer drugs against oral cancer cell , We tested the cytotoxi city of the hydroxybacteriochlorine by MTT assay and observed the cell death pattern(apoptosis or necrosis) after PDT by hoechst 33342 and propidium iodide s taining methods, lC50 value of the hydroxybac teriochlorine was 3 1 , 3 ng/ n띠, At higher doses of hydroxybacteriochlori ne () 60ng/ rnQ) , cancer cells died exclus ively by necrosis after PDT By contrast, at lC50 value, hydroxybacteri ochlorine induced cancer cell to undergo apop totic c e ll death, The induct ion begins approximately 6 hours a fter PDT, We inves tigates intrace l1 ular localization of hydroxybacte riochlorine by oral cancel‘ cell via confocal laser scanning mi croscopy, Oral cancer cells dua l-stained with hydrox ybacteriochlo1' ine and organelle-specific flu orescence probes (Mi totracker , Lysotracke1', ER- Tracker) revealed an intracellular f1 uores c ence dis tribution restricted to cyt oplasmic compartments with no det ectable fluorescence in the nucleus, Confocal im ages of cells containing hydroxybacte1'iochl orine were never overla p to mitochondria, lysosome . endoplasmic reticulum when digita lly overla pped with tqe organel1e-specific f1 uorescence p1'obe images o{' the same cells These results demons trated tha t the hydroxybacte1' iochlorine may have a fun ction as a photosensitizer and cytotoxicity hydroxy bacteriochlo1'ine for o1'al cancer cell is more sensitive than head & neck cancer cell 0 1' ce1'vical cancer cell Therefore PDT using hydroxybacte1'iochl orine is suita ble treatment for oral cavity carcinoma patients
        5973.
        2007.10 KCI 등재 구독 인증기관·개인회원 무료
        Cancer cure and survival rate related directly to the stage of the cancer at the time of diagnosis. New techniques fOl ea rly screen system and diagnosis of normal and cancer a re required. Here, we investigate optical properties-based optical s igna tures of normal and cancer tissues that are different chemica lly and physically. At least 7 cases of each tissue type‘ including epidermis. dermis . subcutaneous fat. keratin pearl ‘ muscle, bone. skin. normal and cance r. were measured. As a result. difference in absorption, transmi ssion and reflectance of normal and cancer in oral tissue have the potential to pro vide for cancer screening. In particular. measuring transrnission in 400 nm to 800 nm (inclusive of 450 nmfor NADH. 540 nm 1'0 1' collagen) ‘ t his group noted a difference in auto-fluorescence spectra between normal and cancer specimens . We also noted that normal specimens are cha racterized by a slightly higher reflectance than cancer specimens in the 400 to 800nm And a bsorpt ion of normal is lower than cancer specimens. The diffe rences in transmission. refl ectance and absorpti on between normal and cancer s pecimens were statistically analyzed using student t-test. [n t his study. absor ption. t ransmi ssion and reflectance have been suggested as optimal for best discrirnination between normal and oral cancer specimen. We suggest that a optical integrating sphere is a useful tool for cancer sc reening. The results suggests the potentia l of an effec tive diagnosis system and accurate normal and cancerous tissue's optical coeffi cient
        5974.
        2007.10 KCI 등재 구독 인증기관·개인회원 무료
        For many years, experience has been accumulated on embryo and gamete manipulation in mammals, The present work is an introduction of these techniques and their possible application in human embryology in s pecific cases, Mammalian c1on ing has been studied by many groups, but the success rate is sti ll low‘ Removal of maternal chromosomes from unfertil ized oocytes and injection of donor cells into enucleated oocytes are the most important factors for the improvement of cloning effi cien cy, Here, we introduce a novel one-step rnicromanipulation (OSM) system and laser-assisted zona pellucida piel'cing technique (LAZP) , 1n genera l, somatic cell nuclear transfer (SCNT) is completed by many processes including enucleation and donor cell fusion , Howevel', OSM is a simple method because donor cell is directly injected into ooplasm without fusion pl'ocess, 1n addition, chromosomal enucleation and donor cell inj ec tion are perfOl‘med simultaneously in OSM, While OSM was a pplied to porcine SCNT, LAZP was a pplied to murine SCNT, This rninirni zed the use of piezo-dri ven micromanipul ator (P1EZO) , I'educing chances 0 1' problems caused by P1EZO pulses, LAZP reduced time that took to pierce zona pellucida in removal of nucleus fl'om oocyte and somatic cell injection, which might have taken longer time with P1EZO, The simple , new OSM and LAZP system may help to enable large scale cloning by reduction of procedural steps, Pa l'thenogenesis de scribes the growth and development of an embryo without fertilization by a male Parthenogenetic ES cell s (PESCs) can be a useful cell source for tissue I'epail‘ and I'egeneration , Moreover , the defects in full-term developrnent of this PESCs enable researc hers to avoid the ethical concern , Here, the author showed that PESCs can differentiate into osteogenic lineage, The PESCs were induced osteogenic dlfferentlatlon The osteoblas t-specific gene expression such as osteocalcine, osteopontine, osteonectin, bone-sialo protein‘ coll agen type-l and alka line phos phatase showed osteogenic potential of differentiated PESCs, The author also focused on the neuronal induction of murine PESCs by simplified neurona l induction system to generate doparninergic (DA) neurons , As a result , PESCs were differentiated into nestin and Tuj-l positive cell s successfully, a lthough t he generation of DA neuron was Illruted For murine embryo cul ture, novel oil-free microtube cul tu re system was applied , This new culture system provides oil-free cu ltu re condi t ions and is easy to handle It was also associated with faster development and mOl'e t l'ophectodel'mal cells , which will enhance the development of murine embl'Yos to fur t hel' stages ,