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Lim, Sang-Soon,Kim, Ju-Heon,Kwon, Beomjin,Kim, Seong Keun,Park, Hyung-Ho,Lee, Ki-Suk,Baik, Jeong Min,Choi, Won Jun,Kim, Dong-Ik,Hyun, Dow-Bin,Kim, Jin-Sang,Baek, Seung-Hyub Elsevier 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.678 No.-
<P><B>Abstract</B></P> <P>As a field-assisted technique, spark plasma sintering (SPS) enables densification of specimens in a very short period of time compared to other sintering techniques. For high performance thermoelectric material synthesis, SPS is widely used to fabricate nanograin-structured thermoelectric materials by rapidly densifying the nanopowders suppressing grain growth. However, the microstructural evolution behavior of thermoelectric materials by SPS, another important process during sintering, has been rarely studied. Here, we explore SPS as a tool to control the microstructure by long-time SPS. Using p-type (Bi<SUB>0.25</SUB>Sb<SUB>0.75</SUB>)<SUB>2</SUB>Te<SUB>3</SUB> thermoelectric materials as a model system, we systematically vary SPS temperature and time to understand the correlations between SPS conditions, microstructural evolution, and the thermoelectric properties. Our results show that the relatively low eutectic temperature (∼420 °C) and the existence of volatile tellurium (Te) are critical factors to determine both microstructure and thermoelectric property. In the liquid-phase sintering regime, rapid evaporation of Te leads to a strong dependence of thermoelectric property on SPS time. On the other hand, in the solid-phase sintering regime, there is a weak dependence on SPS time. The optimum thermoelectric figure-of-merit (Z) of 2.93 × 10<SUP>−3</SUP>/K is achieved by SPS at 500 °C for 30 min. Our results will provide an insight on the optimization of SPS conditions for materials containing volatile elements with low eutectic temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spark plasma sintering (SPS) is used to synthesize the thermoelectric (Bi<SUB>0.25</SUB>Sb<SUB>0.75</SUB>)<SUB>2</SUB>Te<SUB>3</SUB>. </LI> <LI> Liquid phase and volatile element are a key for the microstructure and thermoelectric property. </LI> <LI> Thermoelectric figure-of-merit of 2.9 × 10<SUP>−3</SUP>/K is achieved at 500 °C for 30 min. </LI> </UL> </P>
원인 불명의 실신 환자의 진단에 있어서 Head - up tilt Test 의 유용성과 혈관미주신경성 실신 환자의 임상적 특징
윤호중(Ho Joong Youn),정욱성(Wook Sung Chung),백상홍(Sang Hong Baek),김철민(Chul Min Kim),박인수(In Soo Park),김재형(Jae Hyung Kim),최규보(Kyu Bo Choi),홍순조(Soon Jo Hong) 대한내과학회 1994 대한내과학회지 Vol.47 No.2
N/A Background: Syncope, defined as a transient loss of consciousness, is a frequently encountered symptom, but despite thorough clinical and invasive diagnostic investigation, the cause of syncope remains unexplained. In recent years, head-up tilt test has been of increasing interest as a diagnostic aids in patients with unexplained syncope. We studied to define the usefulness of various diagnostic test in the evaluation of patients with recurrent syncope, to assess the usefulness of head-up tilt test in the working of syncope of unknown origin and to evaluate the clinical characteristics of subgroups of patients with syncope induced by head-up tilt test. Methods: Between June, 1991 and November, 1992 at St. Mary`s hospital, 21 patients with history of syncope and 24 control subjects without history of syncope underwent 60° head-up tild test for 60 min. Results: 1) The definite cause for recurrent syncope were diagnosed in 10 of patients (47,6%) after clinical and invasive tests. 2) During head-up tilt test, vasovagal responses were provoked in 5 of 21 patients (23.8%) with recurrent syncope and 1 of 24 patients (4.2%) without syncope (p<0,05). 3) The head-up tilt test induced symptomatic bradycardia or hypotension in 3 of 10 patients (30%.) with negative electrophysiologic results. 4) During tilt induced vasovagal response, a) mean heart rate decreased to 42±24 beat/min from supine control of 70±12 beat/min (p<0. 05), b) mean systolic blood pressure decreased to 95±12 mmHg from supine control of 120±S mmHg (p<0,05), c) mean diastolic blood pressure decreased to 60±21mmHg from supine control of 72±13 mmHg (p<0.05), d) the time interval to onset of vasovagal response was 22±12 min. Conclusions: 1) In a large proportion of patients with recurrent syncope, the diagnosis remains unexplained despite a neurologic and cardiologic investigation including an electrophysiologic study. 2) Vasovagal responses are frequent cause in patients with recurrent unexplained syncope. 3) The head-up tilt test may be a simple, safe and highly yielding provocative test in the investigation of syncope of unknown origin.
Biswas, Pranab,Cho, Seong Rae,Kim, Jong-Woo,Baek, Sung-Doo,Myoung, Jae-Min IOP 2017 Nanotechnology Vol.28 No.22
<P>In this study, plasmonic silver (Ag) nanoparticle-(NP) anchored ZnO nanorods (NRs) and nanotube-(NT) based UV photodetectors are demonstrated. Here, Ag NPs are synthesized and anchored by using a room-temperature photochemical method by exposing the precursor solution in UV radiation. In order to achieve a stronger surface plasmon resonance (SPR) and minimum agglomeration, the photochemical method is optimized with a precursor concentration of 5 mmol, a UV intensity of 0.4 mWаиаcm<SUP>−2</SUP>, and an exposure time of 30 min. An asymmetry around 380 nm in the absorption spectra of the NP solution indicates the presence of plasmonic resonance in that region. Upon anchoring the Ag NPs, ZnO NRs show enhanced band edge emission (380–400 nm) and the emission is further significantly increased in Ag NP-anchored ZnO NTs. The on/off ratio and photoresponse properties of the UV photodetectors are enhanced significantly after anchoring Ag NPs on the ZnO nanostructures. It is believed that the near-field coupling of SPR causes an optical enhancement of ZnO, whereas the bridging effect and hot-electron transfer to the conduction band of ZnO by plasmonic Ag NPs, anchored in close proximity, gives rise to a faster response of the photodetectors.</P>
Baek, Jong Min,Ahn, Sung-Jun,Cheon, Yoon-Hee,Lee, Myeung Su,Oh, Jaemin,Kim, Ju-Young SPANDIDOS PUBLICATIONS 2017 MOLECULAR MEDICINE REPORTS Vol. No.
<P>The adipokine nicotinamide phosphoribosyltransferase (<I>Nampt</I>), also known as pre-B-cell colony-enhancing factor or the insulin-mimetic hormone visfatin, has a crucial role in the conversion of nicotinamide to nicotinamide mononucleotide during biosynthesis of the coenzyme nicotinamide adenine dinucleotide. Previous reports have demonstrated the inhibitory effects of <I>Nampt</I> on osteoclast formation from human peripheral blood mononuclear cells and CD14+ monocytes. However, the effects of <I>Nampt</I> on bone marrow macrophage (BMM)-derived osteoclastogenesis and its precise role in the process remain unclear. The present <I>in vitro</I> study used recombinant <I>Nampt</I> and BMMs as osteoclast precursors demonstrated that <I>Nampt</I> suppresses receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis by decreasing the phosphorylation of various early signal transducers, including c-Jun N-terminal kinase, Akt, glycogen synthase kinase-3 β, Bruton's tyrosine kinase and phospholipase C γ-2. In addition, western blotting and reverse transcription-quantitative polymerase chain reaction analysis indicated that Nampt downregulates the mRNA and protein expression levels of c-Fos and nuclear factor of activated T cells, cytoplasmic 1, leading to a decrease in the expression of osteoclast-specific genes including tartrate-resistant acid phosphatase, osteoclast-associated receptor and cathepsin K. However, the bone-resorbing activity of mature osteoclasts treated with <I>Nampt</I> was similar to untreated control osteoclasts. This finding indicates that Nampt exerts its anti-osteoclastogenic activity by targeting osteoclast precursor cells rather than mature osteoclasts. Consequently, the present study demonstrated that Nampt acts as a negative regulator of RANKL-mediated differentiation of BMMs into osteoclasts, suggesting the potential therapeutic targets to treat bone-related disorders such as osteoporosis.</P>
Comparative serology of human brucellosis in Korea
( Sung Il Lee ),( Min Jung Choi ),( Jin Hur ),( Md Ariful Islam ),( Mst Minara Khatun ),( Byeong Kirl Baek ),( Chang Seup Lee ),( Ibulaimu Kakoma ),( Stephen M Boyle ),( Nammalwar Sriranganathan ),( E 한국가축위생학회 2008 韓國家畜衛生學會誌 Vol.31 No.3
The study was carried out to evaluate the diagnostic efficacy of the tube agglutination test(TAT), enzyme-linked immunosorbent assay(ELISA) and the 2-Mercaptoethanol agglutination test(2-MAT) to detect human brucellosis patients in Korea. We examined 87 serum samples of people in the rural farm areas where bovine brucellosis had been reported. People in this study were divided into seven groups- farmers and their families, veterinarians, veterinary quarantine workers, livestock health control officers, artificial inseminators, livestock traders and healthy control individuals. Among 87 people, 65 were males and 22 were females ranging in age from 13 to 72 years. Of 87 serum samples, ELISA detected 21.84%, TAT detected 11.50% and 2-MAT detected 8.05% Brucella positive sera. Brucella specific IgG ELISA antibody titer was recorder higher in the individuals between the ages of 50 and 65 years. The highest prevalence rate of brucellosis(29.4%) was recorded in the cattle farmers and their family members followed by quarantine veterinary office workers(25%) and practicing veterinarians(11.1%). The majority of the Brucella sero-positive individuals in this study had a history of direct contact with animals.
Characterisation of the major carotenoids in the plasma of the Eurasian magpie (Pica pica) nestlings
Sang-im Lee,Min Jung Baek,Jae Chun Choe,Piotr G. Jablonski 한국조류학회II 2017 한국조류학회지 Vol.24 No.1
Since carotenoids can serve as antioxidants and/or immune stimulants, it has been assumed that deposition of carotenoids in feathers or bills can reveal the health status in birds. In order to study the function of carotenoids as signals or immune stimulants, it is necessary to characterise the types of carotenoid molecules in the study species. In this preliminary study, we examined the types of carotenoids in the plasma of four nestlings of the Eurasian magpie (Pica pica) using mass spectrometry. We found that lutein or zeaxanthin is the major carotenoid in the plasma of magpie nestlings. Some minor constituents of carotenoids could be regarded as the metabolized forms of lutein or zeaxanthin. The plasma of magpie nestlings contained both yellow carotenoids such as lutein and zeaxanthin and red carotenoids such as astaxanthin, which may result in the varying degrees of redness in the plasma among the individuals.
Baek, Young-jae,Kim, Jung-Han,Song, Jae-Min,Yoon, Sang-Yong,Kim, Hong-Sung,Shin, Sang-Hun Korean Association of Maxillofacial Plastic and Re 2016 Maxillofacial Plastic Reconstructive Surgery Vol.38 No.-
Background: In guided bone regeneration (GBR) technique, many materials have been used for improving biological effectiveness by adding on membranes. The new membrane which was constructed with chitin-fibroin-hydroxyapatite (CNF/HAP) was compared with a collagen membrane (Bio-$Gide^{(R)}$) by means of micro-computed tomography. Methods: Fifty-four rats were used in this study. A critical-sized (8 mm) bony defect was created in the calvaria with a trephine bur. The CNF/HAP membrane was prepared by thermally induced phase separation. In the experimental group (n = 18), the CNF/HAP membrane was used to cover the bony defect, and in the control group (n = 18), a resorbable collagen membrane (Bio-$Gide^{(R)}$) was used. In the negative control group (n = 18), no membrane was used. In each group, six animals were euthanized at 2, 4, and 8 weeks after surgery. The specimens were analyzed using micro-CT. Results: Bone volume (BV) and bone mineral density (BMD) of the new bone showed significant difference between the negative control group and membrane groups (P < 0.05). However, between two membranes, the difference was not significant. Conclusions: The CNF/HAP membrane has significant effect on the new bone formation and has the potential to be applied for guided bone regeneration.