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https://www.readbyqxmd.com/read/29352470/a-laser-optical-method-for-predicting-adulteration-of-clover-honey-bee
#1
A E El-Raie, H E Hassan, A A Abd El-Rahman, R A Shaimaa
The authenticity of honey is great importance for commercial and health reasons. Adulteration of honey bee with cheaper sweetening materials has been used. The objectives of this study were: 1) To evaluate the quality of honey bee according to physicochemical characteristics, 2) To estimate the transmission property of prediction of honey using visible laser technique, and 3) Possibility of adulteration of honey bee according to high transmission intensity of laser beam through Clover honey bee. Helium-neon (He-Ne) laser in the visible light with wavelengths 632...
January 20, 2018: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/29341710/vibrational-action-spectroscopy-of-solids-new-surface-sensitive-technique
#2
Zongfang Wu, Agata Płucienik, Felix E Feiten, Matthias Naschitzki, Walter Wachsmann, Sandy Gewinner, Wieland Schöllkopf, Volker Staemmler, Helmut Kuhlenbeck, Hans-Joachim Freund
Vibrational action spectroscopy employing infrared radiation from a free-electron laser has been successfully used for many years to study the vibrational and structural properties of gas phase aggregates. Despite the high sensitivity of this method no relevant studies have yet been conducted for solid sample surfaces. We have set up an experiment for the application of this method to such targets, using infrared light from the free-electron laser of the Fritz Haber Institute. In this Letter, we present first results of this technique with adsorbed argon and neon atoms as messengers...
September 29, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29341365/how-and-why-helium-permeates-non-porous-arsenolite-under-high-pressure
#3
Piotr Aleksander Guńka, Michał Hapka, Michael Hanfland, Maciej Dranka, Grzegorz Chałasiński, Janusz Zachara
Investigations into the helium permeation of arsenolite, the cubic, molecular arsenic(III) oxide polymorph As₄O₆, were carried out in order to understand how and why arsenolite helium clathrate As₄O₆∙2He is formed. High-pressure synchrotron X-ray diffraction experiments on arsenolite single crystals revealed that the permeation of helium into non-porous arsenolite depends on the time during which the crystal is subjected to high pressure and on the crystal history. The single crystal was totally transformed into As₄O₆·2He within 45 h under 5 GPa...
January 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29320205/heavy-atom-secondary-kinetic-isotope-effect-on-h-tunneling
#4
André Kristopher Eckhardt, Dennis Gerbig, Peter R Schreiner
Although frequently employed, heavy atom kinetic isotope effects (KIE) have not been reported for quantum mechanical tunneling reactions. Here we examine the secondary KIE through 13C substitution of the carbene atom in methylhydroxycarbene (H3C-C̈-OH) in its [1,2]H tunneling shift reaction to acetaldehyde (H3C-CHO). Our study employs matrix isolation IR spectroscopy in various inert gases and quantum chemical computations. Depending on the choice of the matrix host gas the KIE varies within a range of 1.0 in xenon and 1...
January 10, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29289181/note-simple-100-hz-n2-laser-with-longitudinal-discharge-tube-and-high-voltage-power-supply-using-neon-sign-transformer
#5
K Uno, T Jitsuno
We developed a longitudinally excited N2 laser with a simple driver circuit and a simple power supply. The N2 laser consisted of a 20 cm-long glass tube with an inner diameter of 2.5 mm, a normal stable resonator formed by flat mirrors, a variable transformer, a neon sign transformer, a spark gap, and a 200 pF capacitance. The N2 laser produced a laser pulse with an energy of 379 nJ and a pulse width of 7.5 ns at a repetition rate of 100 Hz. The laser beam was circular and had a Gaussian profile with a correlation factor of 0...
December 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29289050/the-fractal-geometry-of-hartree-fock
#6
Friethjof Theel, Antonia Karamatskou, Robin Santra
The Hartree-Fock method is an important approximation for the ground-state electronic wave function of atoms and molecules so that its usage is widespread in computational chemistry and physics. The Hartree-Fock method is an iterative procedure in which the electronic wave functions of the occupied orbitals are determined. The set of functions found in one step builds the basis for the next iteration step. In this work, we interpret the Hartree-Fock method as a dynamical system since dynamical systems are iterations where iteration steps represent the time development of the system, as encountered in the theory of fractals...
December 2017: Chaos
https://www.readbyqxmd.com/read/29286739/direct-measurement-of-the-key-e_-c-m-456%C3%A2-%C3%A2-kev-resonance-in-the-astrophysical-19-ne-p-%C3%AE-20-na-reaction-and-its-relevance-for-explosive-binary-systems
#7
R Wilkinson, G Lotay, A Lennarz, C Ruiz, G Christian, C Akers, W N Catford, A A Chen, D Connolly, B Davids, D A Hutcheon, D Jedrejcic, A M Laird, L Martin, E McNeice, J Riley, M Williams
We have performed a direct measurement of the ^{19}Ne(p,γ)^{20}Na reaction in inverse kinematics using a beam of radioactive ^{19}Ne. The key astrophysical resonance in the ^{19}Ne+p system has been definitely measured for the first time at E_{c.m.}=456_{-2}^{+5}  keV with an associated strength of 17_{-5}^{+7}  meV. The present results are in agreement with resonance strength upper limits set by previous direct measurements, as well as resonance energies inferred from precision (^{3}He, t) charge exchange reactions...
December 15, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29261311/laser-ablated-u-atom-reactions-with-cn-2-to-form-unc-u-nc-2-and-u-nc-4-matrix-infrared-spectra-and-quantum-chemical-calculations
#8
Zongtang Fang, Edward B Garner, David A Dixon, Yu Gong, Lester Andrews, Benjamin K Liebov
Laser-ablated U atoms react with (CN)2 in excess argon and neon during co-deposition at 4 K to form UNC, U(NC)2, and U(NC)4 as the major uranium bearing products, which are identified from their matrix infrared spectra using cyanogen substituted with 13C and 15N and from quantum chemical calculations. The 12/13CN and C14/15N isotopic frequency ratios computed for the U(NC)1,2,4 molecules agree better with the observed values than those calculated for the U(CN)1,2,4 isomers. Multiplets using mixed isotopic cyanogens reveal the stoichiometries of these products, and the band positions and quantum chemical calculations confirm the isocyanide bonding arrangements, which are 14 and 51 kJ/mol more stable than the cyanide isomers for UNC and U(NC)2, respectively, and 62 kJ/mol for U(NC)4 in the isolated gas phase at the CCSD(T)/CBS level...
December 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29246042/transport-coefficients-of-helium-neon-mixtures-at-low-density-computed-from-ab-initio-potentials
#9
Felix Sharipov, Victor J Benites
The viscosity, thermal conductivity, diffusion coefficient, and thermal diffusion factor of helium-neon mixtures at low density are calculated for a wide range of temperature and for various molar fractions. The Chapman-Enskog method is employed considering the 10th order of the Sonine polynomial expansion. Ab initio potentials for intermolecular interactions are used to calculate the omega-integrals. The relative numerical error of the present results obtained for the potentials used here is less than 7 × 10-5 for the thermal diffusion factor and 2 × 10-5 for all the other coefficients...
December 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29245790/compact-and-flexible-harmonic-generator-and-three-color-synthesizer-for-femtosecond-coherent-control-and-time-resolved-studies
#10
C Burger, W F Frisch, T M Kardaś, M Trubetskov, V Pervak, R Moshammer, B Bergues, M F Kling, P Wnuk
Intense, multi-color laser fields permit the control of the ionization of atoms and the steering of electron dynamics. Here, we present the efficient collinear creation of the second and third harmonic of a 790 nm femtosecond laser followed by a versatile field synthesizer for the three color fields' composition. Using the device, we investigate the strong-field ionization of neon by fields composed of the fundamental, and the second or third harmonic. The three-color device offers sufficient flexibility for the coherent control of strong-field processes and for time-resolved pump-probe studies...
December 11, 2017: Optics Express
https://www.readbyqxmd.com/read/29220184/matrix-isolation-and-quantum-chemical-analysis-of-the-c3v-conformer-of-xef6-xeof4-and-their-acetonitrile-adducts
#11
Maxim Gawrilow, Helmut Beckers, Sebastian Riedel, Lan Cheng
A joint experimental-computational study of the molecular structure and vibrational spectra of the XeF6 molecule is reported. The vibrational frequencies, intensities and in particular the isotopic frequency shifts of the vibrational spectra for 129XeF6 and 136XeF6 isotopologues recorded in the neon matrix agree very well with those obtained from relativistic coupledcluster calculations for XeF6 in the C3v structure, thereby strongly support the observation of the C3v conformer of the XeF6 molecule in the neon matrix...
December 8, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29219434/separation-of-isotopes-in-space-and-time-by-gas-surface-atomic-diffraction
#12
Kevin J Nihill, Jacob D Graham, S J Sibener
The separation of isotopes in space and time by gas-surface atomic diffraction is presented as a new means for isotopic enrichment. A supersonic beam of natural abundance neon is scattered from a periodic surface of methyl-terminated silicon, with the ^{20}Ne and ^{22}Ne isotopes scattering into unique diffraction channels. Under the experimental conditions presented in this Letter, a single pass yields an enrichment factor 3.50±0.30 for the less abundant isotope, ^{22}Ne, with extension to multiple passes easily envisioned...
October 27, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29195346/experimental-setup-for-the-growth-of-solid-crystals-of-inert-gases-for-particle-detection
#13
M Guarise, C Braggio, R Calabrese, G Carugno, A Dainelli, A Khanbekyan, E Luppi, E Mariotti, M Poggi, L Tomassetti
Low energy threshold detectors are necessary in many frontier fields of the experimental physics. In this work, we present a novel detection approach based on pure or doped matrices of inert gases solidified at cryogenic temperatures. The small energy release of the incident particle can be transferred directly (in pure crystals) or through a laser-driven ionization (in doped materials) to the electrons of the medium that are then converted into free electrons. The charge collection process of the electrons that consists in their drift within the crystal and their extraction through the solid-vacuum interface gives rise to an electric signal that we exploit for preliminary tests of charge collection and crystal quality...
November 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29195287/a-note-on-the-accuracy-of-ks-dft-densities
#14
Duminda S Ranasinghe, Ajith Perera, Rodney J Bartlett
The accuracy of the density of wave function methods and Kohn-Sham (KS) density functionals is studied using moments of the density, ⟨rn⟩=∫ ρ rrndτ=∫0∞4πr2ρ(r)rndr,where n=-1,-2,0,1,2,and 3 provides information about the short- and long-range behavior of the density. Coupled cluster (CC) singles, doubles, and perturbative triples (CCSD(T)) is considered as the reference density. Three test sets are considered: boron through neon neutral atoms, two and four electron cations, and 3d transition metals...
November 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29167693/approving-cancer-treatments-based-on-endpoints-other-than-overall-survival-an-analysis-of-historical-data-using-the-pace-continuous-innovation-indicators%C3%A2-cii
#15
Neon Brooks, Mario Campone, Silvia Paddock, Scott Shortenhaus, David Grainger, Jacqueline Zummo, Samuel Thomas, Rose Li
Background: There is an active debate about the role that endpoints other than overall survival (OS) should play in the drug approval process. Yet the term 'surrogate endpoint' implies that OS is the only critical metric for regulatory approval of cancer treatments. We systematically analyzed the relationship between U.S. Food and Drug Administration (FDA) approval and publication of OS evidence to understand better the risks and benefits of delaying approval until OS evidence is available...
2017: Drugs in Context
https://www.readbyqxmd.com/read/29166121/photoinduced-transformations-of-indole-and-3-formylindole-monomers-isolated-in-low-temperature-matrices
#16
Igor Reva, Leszek Lapinski, A J Lopes Jesus, Maciej J Nowak
Photochemical transformations were studied for monomers of indole and 3-formylindole isolated in low-temperature noble-gas matrices. Upon UV (λ > 270 nm) irradiation of indole trapped in argon and neon matrices, the initial 1H-form of the compound converted into the 3H-tautomer. Alongside this photoinduced hydrogen-atom transfer, an indolyl radical was also generated by photodetachment of the hydrogen atom from the N1-H bond. Excitation of 3-formylindole isolated in an argon matrix with UV (λ > 335 nm) light led to interconversion between the two conformers of the 1H-tautomer, differing from each other in the orientation of the formyl group (cis or trans)...
November 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29162690/multiple-pathways-in-pressure-induced-phase-transition-of-coesite
#17
Wei Liu, Xuebang Wu, Yunfeng Liang, Changsong Liu, Caetano R Miranda, Sandro Scandolo
High-pressure single-crystal X-ray diffraction method with precise control of hydrostatic conditions, typically with helium or neon as the pressure-transmitting medium, has significantly changed our view on what happens with low-density silica phases under pressure. Coesite is a prototype material for pressure-induced amorphization. However, it was found to transform into a high-pressure octahedral (HPO) phase, or coesite-II and coesite-III. Given that the pressure is believed to be hydrostatic in two recent experiments, the different transformation pathways are striking...
November 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29145103/gold-chlorophyll-a-hybrid-nanoparticles-and-chlorophyll-a-cetyltrimethylammonium-chloride-self-assembled-suprastructures-as-novel-carriers-for-chlorophyll-a-delivery-in-water-medium-photoactivity-and-photostability
#18
Vito Rizzi, Davide Vurro, Tiziana Placido, Paola Fini, Andrea Petrella, Paola Semeraro, Pinalysa Cosma
The stability of Chlorophyll a in water during prolonged exposure, at room temperature, to a neon lamp has been investigated by means of UV-vis and fluorescence spectroscopies. In addition, the Chlorophyll a (photo)stability evaluation in presence of suitable carriers has been performed in order to investigate its reactivity under the same conditions, for possible and future applications in Antimicrobial Photodynamic Therapy. Cetyltrimethylammonium chloride was chosen to solubilize Chlorophyll a in water. While, cetyltrimethylammonium chloride-capped gold nanoparticles offer a great opportunity because combine the Chlorophyll a action, used as a photosensitizer in Antimicrobial Photodynamic Therapy, with gold nanoparticles effect used in photothermal therapy...
November 9, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29099133/sub-doppler-infrared-spectroscopy-of-resonance-stabilized-hydrocarbon-intermediates-%C3%AE-3-%C3%AE-4-ch-stretch-modes-and-ch2-internal-rotor-dynamics-of-benzyl-radical
#19
A Kortyna, A J Samin, T A Miller, D J Nesbitt
Highly reactive benzyl radicals are generated by electron dissociative attachment to benzyl chloride doped into a neon-hydrogen-helium discharge and immediately cooled to Trot = 15 K in a high density, supersonic slit expansion environment. The sub-Doppler spectra are fit to an asymmetric-top rotational Hamiltonian, thereby yielding spectroscopic constants for the ground (v = 0) and first excited (v = 1, ν3, ν4) vibrational levels of the ground electronic state. The rotational constants obtained for the ground state are in good agreement with previous laser induced fluorescence measurements (LIF), with vibrational band origins (ν3 = 3073...
November 3, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29097491/photoionization-in-the-time-and-frequency-domain
#20
M Isinger, R J Squibb, D Busto, S Zhong, A Harth, D Kroon, S Nandi, C L Arnold, M Miranda, J M Dahlström, E Lindroth, R Feifel, M Gisselbrecht, A L'Huillier
Ultrafast processes in matter, such as the electron emission after light absorption, can now be studied using ultrashort light pulses of attosecond duration (10(-18) seconds) in the extreme ultraviolet spectral range. The lack of spectral resolution due to the use of short light pulses has raised issues in the interpretation of the experimental results and the comparison with theoretical calculations. We determine photoionization time delays in neon atoms over a 40-electron volt energy range with an interferometric technique combining high temporal and spectral resolution...
November 17, 2017: Science
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