1,720,955 research outputs found
Facile electrochemical detection of botulinum neurotoxin type E using a two-step proteolytic cleavage
No full textFacile electrochemical methods for measuring protease concentration or protease activity are essential for point-of-care testing of toxic proteases. However, electrochemical detection of proteases, such as botulinum neurotoxin type E (BoNT/E), that cleave a peptide bond between two specific amino acid residues is challenging. This study reports a facile and sensitive electrochemical method for BoNT/E detection. The method is based on a two-step proteolytic cleavage using a target BoNT/E light chain (BoNT/E-LC) and an externally supplemented exopeptidase, L-leucine-aminopeptidase (LAP). BoNT/E-LC cleaves a peptide bond between arginine and isoleucine in IDTQNRQIDRI-4-amino-1-naphthol (oligopeptide-AN) to generate isoleucine-AN. Subsequently, LAP cleaves a bond between isoleucine and AN to liberate a free electroactive AN species. The liberated AN participates in electrochemical-chemical-chemical (ECC) redox cycling involving Ru(NH3)(6)(3+), AN, and a reducing agent, which allows a high signal amplification. Electrochemical detection is carried out without surface modification of indium tin oxide electrodes. We show that dithiothreitol is beneficial for enhancing the enzymatic activity of BoNT/E-LC and also for achieving a fast ECC redox cycling. An incubation temperature of 37 degrees C and the use of phosphate buffered saline (PBS) buffer resulted in optimal signal-to-background ratios for efficient BoNT/E detection. BoNT/E-LC could be detected at concentrations of approximately 2.0 pg/mL, 0.2, and 3 ng/mL after 4 h, 2 h, and 15 min incubation in PBS buffer, respectively, and approximately 0.3 ng/mL after 2-h incubation in bottled water. The method developed could be applied in fast, sensitive, and selective detection of any protease that cleaves a peptide bond between two specific amino acid residues.
Influence of surface defects and cross-sectional designs on the fatigue fracture of NiTi rotary files
No full text치의학과/석사[한글]
본 연구는 주사 전자 현미경(Scanning Electron Microscope, SEM)을 통해서 니켈 티타늄(NiTi) 파일의 표면결함이 반복 응력하에서 파일의 조기 파절의 원인이 될 수 있는지, 이에 더하여 NiTi 파일의 단면 형태가 반복 응력하에서의 피로 파절에 영향을 미치는지 알아보기 위한 것이다. #30/.04와 #25/.06 크기의 K3TM(SybronEndo), ProFile(r)(Maillefer), HERO 642(r)(MicroMega) NiTi 파일을 사용하였다. 실험군은 NiTi 파일에 표면 결함을 인위적으로 생성하였고, 대조군은 200배로 확대한 현미경상에서 삭제날 부위에 결함이 없는 군으로 하였다. NiTi 파일은 파일 끝 3mm부위에서 Schneider 법에 의한 40° 만곡을 이루도록 금속핀 사이에 위치시킨 후 300rpm으로 회전시켜서 파절 시간을 측정하였고, 파절된 단면은 주사 전자 현미경으로 관찰하였다.
실험결과 #30/.04 K3TM 파일과 #25/.06 HERO 642(r) 파일은 파절 회전수에 있어서 실험군과 대조군간 통계학적 유의차가 있었고(P<0.05), 나머지 군에서도 실험군이 대조군에 비해 일관되게 파절 시간이 짧게 나타났다. 주사 전자 현미경을 이용해서 파절 단면을 관찰한 결과 기계 가공 과정에서 발생한 홈이나 하방의 표면 손상부위에서 파절이 시작되는 취성파절(brittle fracture) 특징이 나타나고 여기서 연성파절(ductile fracture)로 이행되는 양상을 보였다. 단면 형태에 따른 파절 회전수를 비교했을 때 K3TM가 실험군과 대조군 모두에서 가장 낮은 것으로 나타났다.
이러한 결과는 NiTi 파일의 표면결함이 반복응력하의 피로 파절에 중요한 역할을 한다는 것을 나타낸다. 또한 NiTi 파일의 단면 형태에 따라 파절 시간에 영향을 미칠 수 있음을 알 수 있었다.
[영문]The purpose of this in vitro study was to determine whether the surface defects could results in fatigue fracture of NiTi rotary files by examining the fracture surface of the instrument by SEM, and to compare the fracture time of NiTi rotary files with different flute designs under cyclic loading.
This study examined three groups of rotary NiTi instruments (K3TM, ProFile®, HERO 642®). Of each group, 04 taper, size 30 and 06 taper, size 25 were selected. : 120 in total. Surface defects were created in experimental groups. The instruments were inserted around the stainless steel pins that are used to restrain the instruments with 40 degree of curvature and rotated at 300rpm until they fracture. The time to fracture was measured and the fracture surfaces of each files were observed with scanning electron microscope.
Significant differences in cycles to failure were observed between experimental and control group in Group 2(K3TM) and Group 5(HERO 642®). Different cross-sections demonstrated different cycles to failure. Several of fractured files demonstrated characteristic patterns of brittle fracture consistent with the propagation of pre-existing cracks associated with machining damage. And there was a transition from brittle fracture to ductile failure.
This data indicate that surface defects of NiTi rotary files may significantly decrease fatigue life under experimental conditions. It may be one possible factor for premature fracture of NiTi instrument in clinical practice. Different cross-sections demonstrated different stiffness and therefore different cycles to failure.ope
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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