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81.
Metal reduction at the interface between two immiscible electrolyte solutions (ITIES) has been studied with scanning electrochemical microscopy (SECM). Metal cations in the aqueous phase are reduced by 7,7,8,8‐tetracyanoquinodimethane anion (TCNQ?) residing in the oil phase, methyl isobutyl ketone (MIBK). TCNQ? is formed at the SECM tip by reducing TCNQ, which results in a positive feedback loop between the tip and the ITIES when an electron is donated to a metal cation. The effect of the Galvani potential difference on the rate of the interfacial electron transfer was investigated, establishing the potential difference either by an additional substrate electrode in the aqueous phase or by an a common ion in both phases. It is shown that the Galvani potential difference as a driving force does enable TCNQ? mediated Cu2+ reduction. Finite element method (FEM) simulations were run to provide information on the reaction kinetics and stoichiometry. 相似文献
82.
E. Valtonen J. J. Torsti E. Riihonen E. Vainikka M. Lumme M. Nieminen J. Peltonen H. Arvela 《Il Nuovo Cimento C》1987,10(1):102-108
Summary The time structure of the ground-level event on February 16, 1984 was studied by using 30 s data of the Turku double neutron
monitor. The onset time of the event was found to be (09:06:00±1) min U.T. The time between the injection of protons from
the flare site and release of relativistic particles into interplanetary space was (6÷7) min. The linear rise rate of the
event at Turku was 5.4%/min and the rise time (5±1) min. The event was complicated in structure consisting of at least two
separate pulses of particles, the first lasting for about 14 min and the second about 8 min.
Riassunto Si è studiata la struttura dell'evento a livello del suolo verificatosi il 16 Febbraio 1984 usando i dati a 30 s del doppio monitor neutronico Turku. Si è trovato che il tempo all'inizio dell'evento a Turku era (09:06:00±1) min U.T. Il tempo tra l'iniezione di protoni dal sito di brillamento e il rilascio di particelle relativistiche nello spazio interplanetario era di (6÷7) min. Il tasso lineare d'incremento dell'evento a Turku era di 5.4%/min e il tempo di incremento era di (5±1) min. L'evento era complicato nella sua struttura, che consiste in almeno due impulsi separati di particelle, il primo di durata di circa 14 min e il secondo di circa 8 min.
Резюме Исследуется временная структура события на уровне земли 16 февраля 1984 г., используя 30-секундные данные с двойного нейтронного монитора в Турку. Время начала события составляет 09:06:00±1 минут U.T. Время между инжекцией протонов от места вспымки и высвобождением релятивистских частиц в межпланетное пространство составило (6÷7) минут. Линейная скорость возрастания события в Турку была 5.4%/мин, а время возрастания было (5±1) минут. Это событие имело сложную структуру, которая состоит, по крайней мере, из двух изолированных импульсов частиц, первый имеет продолжительность около 14 минут, а второй—около 8 минут.相似文献
83.
Michiko Watanabe Midori Hitomi Kathy van der Wee Florence Rothenberg Steven A Fisher Robert Zucker Kathy K H Svoboda Edie C Goldsmith Kaisa M Heiskanen Anna-Liisa Nieminen 《Microscopy and microanalysis》2002,8(5):375-391
Programmed cell death or apoptosis occurs in many tissues during normal development and in the normal homeostasis of adult tissues. Apoptosis also plays a significant role in abnormal development and disease. Increased interest in apoptosis and cell death in general has resulted in the development of new techniques and the revival of old ones. Each assay has its advantages and disadvantages that can render it appropriate and useful for one application, but inappropriate or difficult to use in another. Understanding the strengths and limitations of the assays would allow investigators to select the best methods for their needs. 相似文献
84.
We describe the first calculation of the stopping power of an electron gas for slow ions using the density-functional formalism. We evaluate the nonlinear self-consistent potential around the ion and from scattering theory determine the energy loss directly. Comparison with the results of linear theory is made. 相似文献
85.
K. J. Jalkanen I. M. Degtyarenko R. M. Nieminen X. Cao L. A. Nafie F. Zhu L. D. Barron 《Theoretical chemistry accounts》2008,119(1-3):191-210
In this work we have utilized recent density functional theory Born-Oppenheimer molecular dynamics simulations to determine
the first principles locations of the water molecules in the first solvation shell which are responsible for stabilizing the
zwitterionic structure of L-alanine. Previous works have used chemical intuition or classical molecular dynamics simulations to position the water molecules.
In addition, a complete shell of water molecules was not previously used, only the water molecules which were thought to be
strongly interacting (H-bonded) with the zwitterionic species. In a previous work by Tajkhorshid et al. (J Phys Chem B 102:5899)
the L-alanine zwitterion was stabilized by 4 water molecules, and a subsequent work by Frimand et al. (Chem Phys 255:165) the number
was increased to 9 water molecules. Here we found that 20 water molecules are necessary to fully encapsulate the zwitterionic
species when the molecule is embedded within a droplet of water, while 11 water molecules are necessary to encapsulate the
polar region with the methyl group exposed to the surface, where it migrates during the MD simulation. Here we present our
vibrational absorption, vibrational circular dichroism and Raman and Raman optical activity simulations, which we compare
to the previous simulations and experimental results. In addition, we report new VA, VCD, Raman and ROA measurements for L-alanine in aqueous solution with the latest commercially available FTIR VA/VCD instrument (Biotools, Jupiter, FL, USA) and
Raman/ROA instrument (Biotools). The signal to noise of the spectra of L-alanine measured with these new instruments is significantly better than the previously reported spectra. Finally we reinvestigate
the causes for the stability of the Pπ structure of the alanine dipeptide, also called N-acetyl-L-alanine N′-methylamide, in aqueous solution. Previously we utilized the B3LYP/6-31G* + Onsager continuum level of theory to investigate
the stability of the NALANMA4WC Han et al. (J Phys Chem B 102:2587) Here we use the B3PW91 and B3LYP hybrid exchange correlation
functionals, the aug-cc-pVDZ basis set and the PCM and CPCM (COSMO) continuum solvent models, in addition to the Onsager and
no continuum solvent model. Here by the comparison of the VA, VCD, Raman and ROA spectra we can confirm the stability of the
NALANMA4WC due to the strong hydrogen bonding between the four water molecules and the peptide polar groups. Hence we advocate
the use of explicit water molecules and continuum solvent treatment for all future spectral simulations of amino acids, peptides
and proteins in aqueous solution, as even the structure (conformer) present cannot always be found without this level of theory.
Festschift in Honor of Philip J. Stephens’ 65th Birthday.
During the proof stage of this article a very relevant article has been published by M. Losada and Y. Xu titled “Chirality
transfer through hydrogen-bonding: Experimental and ab initio analyses of vibrational circular dichroism spectra of methyl
lactate in water” in Phys Chem Chem Phys 2007, 9: 3127–3135. In that work they confirm that the effects of water are seen
in the VCD spectra and hence it is fundamental to include explicit water molecules in modeling studies of the vibrational
spectra of biomolecules in aqueous solution. 相似文献
86.
Proper peer review and quality of published articles are often regarded as signs of reliable scientific journals. The aim of this study was to compare whether the quality of statistical reporting and data presentation differs among articles published in ‘predatory dental journals’ and in other dental journals. We evaluated 50 articles published in ‘predatory open access (OA) journals’ and 100 clinical trials published in legitimate dental journals between 2019 and 2020. The quality of statistical reporting and data presentation of each paper was assessed on a scale from 0 (poor) to 10 (high). The mean (SD) quality score of the statistical reporting and data presentation was 2.5 (1.4) for the predatory OA journals, 4.8 (1.8) for the legitimate OA journals, and 5.6 (1.8) for the more visible dental journals. The mean values differed significantly (p < 0.001). The quality of statistical reporting of clinical studies published in predatory journals was found to be lower than in open access and highly cited journals. This difference in quality is a wake-up call to consume study results critically. Poor statistical reporting indicates wider general lower quality in publications where the authors and journals are less likely to be critiqued by peer review. 相似文献
87.
A. Algora J. L. Taín A. B. Perez B. Rubio J. Agramunt L. Caballero E. Nácher A. Krasznahorkay M. D. Hunyadi J. Gulyás A. Vitéz J. Äystö H. Penttilä S. Rinta-Antila I. Moore T. Eronen A. Jokinen A. Nieminen J. Hakala P. Karvonen A. Kankainen U. Hager T. Sonoda K. Burkard W. Hüller L. Batist W. Gelletly T. Yoshida A. L. Nichols A. Sonzogni 《The European physical journal. Special topics》2007,150(1):383-384
88.
T. Grahn A. Dewald O. Möller R. Julin C. W. Beausang S. Christen I. G. Darby S. Eeckhaudt P. T. Greenlees A. Görgen K. Helariutta J. Jolie H. Kettunen T. Kröll R. Krücken P. Jones S. Juutinen Y. Le Coz M. Leino A.-P. Leppänen P. Maierbeck B. Melon D. A. Meyer P. Nieminen M. Nyman R. Page J. Pakarinen P. Petkov P. Rahkila B. Saha M. Sandzelius J. Sarén C. Scholey J. Uusitalo 《The European physical journal. Special topics》2007,150(1):121-122
Lifetimes of low-lying yrast states in 186Pb and
194Po have been determined by employing, for the first time, the recoil-decay tagging technique in recoil distance Doppler-shift
lifetime measurements. In addition, lifetime measurements of prolate states in 188Pb up to the 8+ state were carried out using the recoil gating method. The deformation parameters
and
for the prolate (186,188Pb) and the oblate (194Po) bands,
respectively, have been extracted from the measured lifetimes.
27.70.+q– 相似文献
89.
We present a density functional theory study of transition metal adatoms on a graphene sheet with vacancy-type defects. We calculate the strain fields near the defects and demonstrate that the strain fields around these defects reach far into the unperturbed hexagonal network and that metal atoms have a high affinity to the non-perfect and strained regions of graphene. Metal atoms are therefore attracted by the reconstructed defects. The increased reactivity of the strained graphene makes it possible to attach metal atoms much more firmly than to pristine graphene and supplies a tool for tailoring the electronic structure of graphene. Finally, we analyze the electronic band structure of graphene with defects and show that some defects open a semiconductor gap in graphene, which may be important for carbon-based nanoelectronics. 相似文献
90.