• 제목/요약/키워드: Columbia

검색결과 665건 처리시간 0.021초

Thermo-sensitive Electrospun Fibrous Magnetic Composite Sheets

  • Choi, Jungsu;Kim, Jinu;Yang, Heejae;Ko, Frank K.;Kim, Ki Hyeon
    • Journal of Magnetics
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    • 제20권3호
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    • pp.215-220
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    • 2015
  • The PVDF fibrous composite filled with iron oxide nanoparticles were prepared by using the electrospinning technique. The electrospun composite have the thickness in the range of $60-80{\mu}m$ with the average fibrous diameters of 500-900 nm. The magnetizations of PVDF fibrous composite filled with iron oxide nanoparticles showed 4.5 emu/g, 3.1 emu/g and 1.6 emu/g at 1.5 T of external magnetic field for 20 wt.%, 10 wt.% and 5 wt.% iron oxide nanoparticles, respectively. The heat elevation of the magnetic composite were measured under various AC magnetic fields, frequency and the ambient temperatures. The temperature reached up to $46.3^{\circ}C$ from $36^{\circ}C$ at 128 Oe and 355 kHz for 20 wt.% iron oxide nanoparticles filled in PVDF fibrous composite sheet. The specific absorption rate of theses sheets increased from 0.041 W/g to 0.236 W/g with the increment of AC magnetic field from 90 Oe to 167 Oe at 190 kHz, respectively.

미국 노인층 관절염 환자들의 성생활: 면담을 위한 질문서 개발 (Sexuality of Older Adults With Arthritis : The Development of an Interview Schedule)

  • 강대혁;로우랜드 오로라;밀러 패트리시아
    • 한국전문물리치료학회지
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    • 제7권4호
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    • pp.16-38
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    • 2000
  • 일상생활동작(activities of daily living)을 주요 목적이자 치료 수단으로 사용하고 있는 작업치료사들이 그 활동 중의 하나인 성적 욕구의 표현(sexual expression)에 대해 체계적인 접근이 미진하다는 지적을 극복 하고자 본 연구가 계획되었다. 특히 만성 장애가 있는 65세 이상 연령층의 성생활에 대해 기술적으로 접근하는 방법을 고안하는 것은 상당한 임상적 의미를 부여 할 수 있다. 본 연구의 주된 목적은 관절염이 65세 이상의 미국인의 성생활에 미치는 영향과 대책에 대한 논의를 작업치료사의 입장에서 자연스럽게 유도하기 위한 질문내용을 고안하는데 있다. 본 연구자들은 광범위한 문헌연구를 바탕으로 7개항의 질문을 작성하여 10명의 노인학 전공 작업치료사들에게 비평을 의뢰하였다. 7명의 작업치료사들이 전문가로서의 세밀한 답변을 해주었고 그들은 공통적으로 일상생활 중의 하나인 성생활이 삶의 질을 향상시키는데 매우 중요한 역할을 함을 강조하였다. 이들 전문가들의 조언을 바탕으로 새로운 질문서가 완성되었다.

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A statistical framework with stiffness proportional damage sensitive features for structural health monitoring

  • Balsamo, Luciana;Mukhopadhyay, Suparno;Betti, Raimondo
    • Smart Structures and Systems
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    • 제15권3호
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    • pp.699-715
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    • 2015
  • A modal parameter based damage sensitive feature (DSF) is defined to mimic the relative change in any diagonal element of the stiffness matrix of a model of a structure. The damage assessment is performed in a statistical pattern recognition framework using empirical complementary cumulative distribution functions (ECCDFs) of the DSFs extracted from measured operational vibration response data. Methods are discussed to perform probabilistic structural health assessment with respect to the following questions: (a) "Is there a change in the current state of the structure compared to the baseline state?", (b) "Does the change indicate a localized stiffness reduction or increase?", with the latter representing a situation of retrofitting operations, and (c) "What is the severity of the change in a probabilistic sense?". To identify a range of normal structural variations due to environmental and operational conditions, lower and upper bound ECCDFs are used to define the baseline structural state. Such an approach attempts to decouple "non-damage" related variations from damage induced changes, and account for the unknown environmental/operational conditions of the current state. The damage assessment procedure is discussed using numerical simulations of ambient vibration testing of a bridge deck system, as well as shake table experimental data from a 4-story steel frame.

Seismic behavior of soft storey mid-rise steel frames with randomly distributed masonry infill

  • Quayyum, Shahriar;Alam, M. Shahria;Rteil, Ahmad
    • Steel and Composite Structures
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    • 제14권6호
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    • pp.523-545
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    • 2013
  • In this study, the effect of presence and distribution of masonry infill walls on the mid-rise steel frame structures having soft ground storey was evaluated by implementing finite element (FE) methods. Masonry infill walls were distributed randomly in the upper storey keeping the ground storey open without any infill walls, thus generating the worst case scenario for seismic events. It was observed from the analysis that there was an increase in the seismic design forces, moments and base shear in presence of randomly distributed masonry infill walls which underlines that these design values need to be amplified when designing a mid-rise soft ground storey steel frame with randomly distributed masonry infill. In addition, it was found that the overstrength related force modification factor increased and the ductility related force modification factor decreased with the increase in the amount of masonry infilled bays and panels. These must be accounted for in the design of mid-rise steel frames. Based on the FE analysis results on two mid-rise steel frames, design equations were proposed for determining the over strength and the ductility related force modification factors. However, it was recommended that these equations to be generalized for other steel frame structure systems based on an extensive analysis.

Synthesis and Evaluation of Antimicrobial Activity of 1, 3, 4-Thiadiazole Analogues for Potential Scaffold

  • Sahu, Sagar;Sahu, Tanesh;Kalyani, Gunjan;Gidwani, Bina
    • 대한약침학회지
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    • 제24권1호
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    • pp.32-40
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    • 2021
  • Objectives: Pathogenic microbes are causal agents for various types of severe and even lethal infectious diseases. Despite of development in medication, bacterial and fungal infections still persist to be a vital problem in health care. Bacteria and several fungal species have shown resistance to antibiotics used in treatment to current medications. Therefore, it is a considerable field of interest in the design and development of novel compounds with antimicrobial activity. Methods: The compounds bearing a heterocyclic ring play an imperative role among other organic compounds with pharmacological activity used as drugs in human for control and cure of various infections. Thiadiazoles containing nitrogen-sulfur atom as part of their cyclic structure which shown wide-ranging application as structural units of biologically active molecules and are very useful intermediates in Medicinal Chemistry. Results: The effectiveness of the thiadiazole nucleus was established by the drugs currently used for the treatment of various infections. 1,3,4-Thiadiazoles and some of their derivatives are widely studied because of their broad spectrum of pharmacological activities. Conclusion: In the present work, a series of 1,3,4-Thiadiazole derivatives were synthesized by cyclization of a group of various benzaldehyde with thiosemicarbazide in the presence of various reagent like FeCl3, HCHO by losing a molecule of water. These derivatives were found to possess prominent antimicrobial activity.

Fertility preservation in pig using ovarian tissues by vitrification method

  • Hwang, In-Sul
    • 한국동물생명공학회지
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    • 제37권2호
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    • pp.106-112
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    • 2022
  • Cryopreservation of porcine ovarian tissue by vitrification method is a promising approach to preserve genetic materials for future use. However, information is not enough and technology still remains in a challenge stage in pig. Therefore, the objective of present study was to determine possibility of vitrification method to cryopreserve porcine ovarian tissue and to confirm an occurrence of cryoinjuries. Briefly, cryoinjuries and apoptosis patterns in vitrified-warmed ovarian tissue were examined by histological evaluation and TUNEL assay respectively. In results, a damaged morphology of oocytes was detected among groups and the rate was significantly (p < 0.05) lower in vitrification group (25.8%) than freezing control group (67.7%), while fresh control group (6.6%) showed significantly (p < 0.05) lower than both groups. In addition, cryoinjury that form a wave pattern of tissues around follicles was found in the frozen control group, but not in the fresh control group as well as in the vitrification group. Apoptotic cells in follicle was observed only in freezing control group while no apoptotic cell was found in both fresh control and vitrification. Similarly, apoptotic patterns of tissues not in follicle were comparable between fresh control and vitrification groups while freezing control group showed increased tendency. Conclusively, it was confirmed that vitrification method has a prevention effect against cryoinjury and this method could be an alternative approach for cryopreservation of genetic material in pigs. Further study is needed to examine the viability of oocytes derived from vitrified-warmed ovarian tissue.