30,333 research outputs found
Circular dichroism and optical rotation of lactamide and 2-aminopropanol in aqueous solution
No full textThe performance of implicit and explicit solvent models (polarizable continuum model (PCM) and microsolvation with positions of water molecules obtained either from molecular dynamics (MD) simulations or quantum mechanical geometry optimization) for calculations of electronic circular dichroism (CD) and optical rotation (OR) is examined for two polar and flexible molecules: lactamide and 2-aminopropanol. The vibrational structure of the CD spectrum is modeled for lactamide. The results are compared with the newly obtained experimental data. The signs of the bands are correctly reproduced using all three methods under investigation and the CAM-B3LYP functional for the CD spectrum of lactamide, but not for 2-aminopropanol. The sign of the calculated optical rotation is correctly predicted by means of PCM, but its magnitude is somewhat underestimated in comparison with experiment for lactamide and overestimated for 2-aminopropanol. To some extent it is rectified by employing explicit hydration. Overall, microsolvation with geometry optimization seems more cost-effective than classical MD, but this is likely to be a consequence of inadequate classical potential and electronic structure model. © 2013 American Chemical Society
Metastable Innershell Molecular State (MIMS) IV: Heteronucleus K-shell MIMS with H+ and He+
No full textAbstractThe model of MIMS (Metastable Innershell Molecular State) has been applied to interpreting the Kα X-ray satellite data of target atoms in H+ and He+ ion impact on Al, Ca and Ti targets. The binding energies of the heteronucleus H-K-MIMS (K-shell MIMS formed with H and a target atom) and He-K-MIMS have been obtained. The binding energy trend of the H-K-MIMS shows a Z2 dependency similar to that of the homonucleus K-MIMS, while that of the He-K-MIMS shows a transitional behavior from the former to the latter. These behaviors were interpreted with the Z-expansion theory of heteronucleus molecules
Comparison of several author indices for gauging academic productivity
No full textBackground
Many author indices exist to gauge academic productivity. Several of these indices are calculated based upon an author's scholarly publication record, but the measurement methodology to calculate each index varies considerably, and the precise function being used, as well as the end result, is often complex and difficult to assess.
Method
Two straightforward methods to weigh author productivity from the publication and citation record were evaluated as possible means for providing a clearer assessment of scholarly activity. The author characteristic index (termed c-index) assigns author rank for each publication based upon author position. The characteristic prime (c') -index normalizes author rank from author position, so that the total weight per publication is unity. The top 10 scholars with keyword 'celiac disease' in the Google Scholar database were then assessed using these metrics. Rankings according to total number of publications, h-index, and c- and c'-indices were compared, then tabulated along with total papers included for assessment, and mean values per paper for author position, number of authors, citations, and year of publication.
Results
The order of the top ten authors with keyword 'celiac disease' varied substantially depending upon whether the h-index, c-index, or c'-index was used as a gauge. The characteristic indices assign credit to authors according to their position in an author list. The affiliated metrics provided a more complete picture of scholarly activity.
Conclusions
Academic achievement by scholars, based upon quantitative publication characteristics, has recently become of interest for evaluating job candidates, for determining work performance, and for bestowing awards and honors. The characteristic indices as described herein are readily calculated and interpreted, and may improve the assessment of scholarly activity
Direct optical transitions at K- and H-point of Brillouin zone in bulk MoS2, MoSe2, WS2, and WSe2
No full textabstract: Modulated reflectance (contactless electroreflectance (CER), photoreflectance (PR), and piezoreflectance (PzR)) has been applied to study direct optical transitions in bulk MoS[subscript 2], MoSe[subscript 2], WS[subscript 2], and WSe[subscript 2]. In order to interpret optical transitions observed in CER, PR, and PzR spectra, the electronic band structure for the four crystals has been calculated from the first principles within the density functional theory for various points of Brillouin zone including K and H points. It is clearly shown that the electronic band structure at H point of Brillouin zone is very symmetric and similar to the electronic band structure at K point, and therefore, direct optical transitions at H point should be expected in modulated reflectance spectra besides the direct optical transitions at the K point of Brillouin zone. This prediction is confirmed by experimental studies of the electronic band structure of MoS[subscript 2], MoSe[subscript 2], WS[subscript 2], and WSe[subscript 2] crystals by CER, PR, and PzR spectroscopy, i.e., techniques which are very sensitive to critical points of Brillouin zone. For the four crystals besides the A transition at K point, an A[subscript H] transition at H point has been observed in CER, PR, and PzR spectra a few tens of meV above the A transition. The spectral difference between A and A[subscript H] transition has been found to be in a very good agreement with theoretical predictions. The second transition at the H point of Brillouin zone (B[subscript H] transition) overlaps spectrally with the B transition at K point because of small energy differences in the valence (conduction) band positions at H and K points. Therefore, an extra resonance which could be related to the B[subscript H] transition is not resolved in modulated reflectance spectra at room temperature for the four crystals.This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Journal of Applied Physics and may be found at http://aip.scitation.org/doi/10.1063/1.4954157
[Letter from K. Okada to Mr. and Mrs. H. Natsumeda]
No full textA letter, written in Japanese from K. Okada in Murray, Utah to Mr. and Mrs. H. Natsumeda inside the Amache Incarceration Camp in Granada, Colorado. Item from Misao Okada’s album.Misao Okada’s scrapbook contains photographs, ephemera, notes, and correspondence documenting her time at Amache and a visit and reunion over 50 years later. The scrapbook also includes materials relating to reparations and events observing Japanese American incarceration
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Letter from George H. Hand to Mr. K. Kodama concerning a claim of damages to crops. July 7, 1925
No full textSecond letter from George H. Hand requesting that Mr. K. Kodama make an appointment to come to his office to sign for a check paying for the damages that incurred to his crops by the Marland Oil Company. See related letter: Letter from Marland Oil Company to the Dominguez Estate Company regarding payout of a claim. July 10, 1924
Letter from George H. Hand to Mr. K. Kodama concerning a claim of damages to crops. July 16, 1924
No full textLetter from George H. Hand requesting that Mr. K. Kodama make an appointment to come to his office to sign for a check paying for the damages that incurred to his crops by the Marland Oil Company. See related letter: Letter from Marland Oil Company to the Dominguez Estate Company regarding payout of a claim. July 10, 1924
Control and Filtering for Discrete Linear Repetitive Processes with H infty and ell 2--ell infty Performance
No full textRepetitive processes are characterized by a series of sweeps, termed passes, through a set of dynamics defined over a finite duration known as the pass length. On each pass an output, termed the pass profile, is produced which acts as a forcing function on, and hence contributes to, the dynamics of the next pass profile. This can lead to oscillations which increase in amplitude in the pass to pass direction and cannot be controlled by standard control laws. Here we give new results on the design of physically based control laws for the sub-class of so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control. The main contribution is to show how control law design can be undertaken within the framework of a general robust filtering problem with guaranteed levels of performance. In particular, we develop algorithms for the design of an H? and dynamic output feedback controller and filter which guarantees that the resulting controlled (filtering error) process, respectively, is stable along the pass and has prescribed disturbance attenuation performance as measured by and – norms
A Polymer Magician: Professor Charlotte K. Williams
No full textAt Organometallics, the Editorial Team has been highlighting a number of scientists that we feel have had a profound impact on the field and perhaps also on ourselves. In this editorial, I wish to introduce another of our Pioneers and Influencers, Professor Charlotte K. Williams from Oxford University. Professor Williams works on three things I love: homogeneous metal catalysts, carbon dioxide, and selectivity. With these ingredients, she is developing impressive protocols for making versatile and sustainable polymers
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