1,720,983 research outputs found
Strikingly Different Photodissociation Dynamics of Thiophenol-d1 and 2-Fluorothiophenol-d1
No full textThe S-D bond dissociation dynamics of thiophenol-d1 and 2-fluorothiophenol-d1 are investigated by using the velocity map ion imaging technique. At many wavelengths λphot in the range of 285- 235nm, both thiophenol-d1 and 2-fluorothiophenol-d1 are dissociated to give the ground(X) and first excited electronic (A) states of cofragments, C6H5S· and C6H4FS·, respectively. Below the conical intersection(CI-1) between diabatic 1ππ*(S1) and 1nπσ*(S2) states, the excitation energies are selected based on the R2PI spectra which are taken to reveal well-resolved excited (S1) vibronic states only in the case of the fluorine substituted thiophenol. With increasing the excitation energy, the excited cofragments are dominantly formed compared to the other state in the 2-fluorothiophenol-d1 dissociation while it is not for the thiophenol-d1. At the wavelength shorter than 250nm, the X state yield of thiophenol-d1 is larger than of 2-fluorothiophenol-d1. These are relevant to the different extent of molecular planarity at the CI-2 between the diabatic 1ππ(S0) and S2 states. Namely, the role of two CIs is revealed thoroughly comparing the valuable observables resulted from the D atom elimination dynamics. For the thiophenol-d1, the dissociation mainly occurs through the torsional mode mediated tunneling along the S-D bond stretch coordinate providing the same nature of two product channels. Meanwhile, it is found out that the A state C6H4FS· product in 2-fluorothiophenol-d1 dissociation has been originated differently from X state product as well as the one for the thiophenol-d1. Intramolecular hydrogen bonding might be responsible for this, giving other reaction pathways along the hydrogen bond coordinate, which imply that the photodissociation product can be controlled by the hydrogen bond strength. The ab initio calculation results are given to support the experimental findings. Meanwhile, the optical excitation at 255< λphot < 260nm, definitely observed three peaks in both molecules have been assigned to the X and A electronic states of cofragments after initially populated to the S1 or S2 states. Finally, it is the hope that further work in experiment and theory will make us to understand conical intersection and tunneling dynamics besides the hydrogen bonded reaction, more in detail
UV Photolysis OF ortho-halogenated thiophenol : The role of hydrogen bonding in photodissociation dynamics
No full textThe experimental techniques of velocity-map ion imaging and resonance-enhanced multiphoton ionization spectroscopy have been used to investigate the dynamics of D atom loss processes from gas phase ortho-halogenated thiophenol-(d1), following photolysis at many wavelengths within the range of vibronic bands of S1 electronic state and further higher excited state. In case of 2-fluorothiophenol-(d1), a dependence of the relative yields of two reaction channels ( ground, X and the first excited state, A of 2-FC6H4S∙ radical ) is observed within S1 (ππ*) region. We’ve expected that molecular planarity by intramolecular hydrogen bonding of F∙∙∙D affects bifurcation dynamics of the second CI, considering previous finding. And relative contribution of S1 (ππ*) & S2 (nσ*) electronic states is investigated along energetics. To shed light on this behavior, potential energy surface (PES) along related reaction coordinates (SD elongation & CSD bending angle & CCSD torsion angle), vertical excitation energy, Frank-Condon simulation and radical energetics are performed using CASPT2, SA-CASSCF, TD-DFT levels.
According to chemical intuition, we are doing experiment on effects strength of hydrogen bond upon fragmentation mechanism using 2-chlorothiophenol-(d1). Comparison electronic spectrum of S1 (ππ*) state and branching ratio with the results of 2-fluorothiophenol-(d1) will serve to highlight intramolecular hydrogen bonding effect on photodissociation dynamics
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
대장암세포에서 진세노사이드 20(S)-Rh2의 JAK2-STATs 경로 억제에 따른 암 침윤에 관한 연구
Full text link학위논문 (석사)-- 서울대학교 대학원 : 의과학과, 2015. 2. 예상규.Ginsenoside Rh2 has been reported to inhibit cancer cell growth and induce apoptosis. The Rh2 has two stereoisomeric forms, 20(S) and 20(R) that have been reported different biological activities. 20(S)-Rh2 mainly has been focused of its anti-cancer and anti-inflammatory effects. However, it is poorly understood whether 20(S)-Rh2 and 20(R)-Rh2 can suppress tumor invasion in human colorectal cancer cells. Here, this study demonstrated that 20(S)-Rh2 strongly inhibited IL-6-induced signal transducer and activator of transcription 3 (STAT3) activation than that of 20(R)-Rh2. 20(S)-Rh2 inhibited STAT3 activation in HCT116 cells when cells were incubated with or without IL-6 stimulation. In addition, this compound effectively inhibited the levels of matrix metalloproteinases (MMPs), including MMP-1, -2, -3 and -9 that are known to be regulated by STAT3, resulting in suppression of the tumor cell invasion in colorectal cancer cells. In parallel, the expression levels of MMPs and tumor cell invasion were suppressed by siSTAT3. The pharmacological activities of 20(S)-Rh2 were identified to be associated with inhibition of the STAT3 upstream regulator JAK2 activation. Interestingly, these inhibitory activities of 20(S)-Rh2 were more potent than those of 20(R)-Rh2. This study further found that 20(S)-Rh2 synergistically enhanced cytotoxicity of HCT116 cells in combinational treatment with other anti-cancer agents, suggesting ginsenoside 20(S)-Rh2 has a promising therapeutic potential against colorectal tumor metastasis as well as to be a combinational partner with classic chemotherapeutic agents in treatment of colorectal cancer.Abstract i
Contents iii
List of tables and figures iv
List of abbreviations v
Introduction 1
Material and Methods 5
Results 8
Discussion 24
References 30
Abstract in Korean 36Maste
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
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