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https://www.readbyqxmd.com/read/28088082/nature-of-phase-transitions-in-ammonium-oxofluorovanadates-a-vibrational-spectroscopy-study-of-nh4-3vo2f4-and-nh4-3vof5
#1
REVIEW
Yu V Gerasimova, A S Oreshonkov, N M Laptash, A N Vtyurin, A S Krylov, N P Shestakov, A A Ershov, A G Kocharova
Two ammonium oxofluorovanadates, (NH4)3VO2F4 and (NH4)3VOF5, have been investigated by temperature-dependent infrared and Raman spectroscopy methods to determine the nature of phase transitions (PT) in these compounds. Dynamics of quasioctahedral groups was simulated within the framework of semi-empirical approach, which justified the cis-conformation of VO2F4(3-) (C2v) and the C4v geometry of VOF5(3-). The observed infrared and Raman spectra of both compounds at room temperature (RT) revealed the presence at least of two crystallographically independent octahedral groups...
January 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28088060/life-cycle-analysis-of-mitigation-methodologies-for-railway-rolling-noise-and-groundbourne-vibration
#2
Mariana Valente Tuler, Sakdirat Kaewunruen
Negative outcomes such as noise and vibration generated by railways have become a challenge for both industry and academia in order to guarantee that the railway system can accomplish its purposes and at the same time provide comfort for users and people living in the neighbourhood along the railway corridor. The research interest on this field has been increasing and the advancement in noise and vibration mitigation methodologies can be observed using various engineering techniques that are constantly put into test to solve such effects...
January 11, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28087449/highly-biocompatible-chitosan-with-super-paramagnetic-calcium-ferrite-cafe2o4-nanoparticle-for-the-release-of-ampicillin
#3
Ram Bilas, K Sriram, P Uma Maheswari, K M Meera Sheriffa Begum
The CaFe2O4 nanoparticles (CFNP) were synthesized using the solution combustion method. The CFNP-chitosan-ampicillin was prepared by the ionic gelation method using tripolyphosphate (TPP). The CFNP, chitosan-CFNP, chitosan-CFNP-ampicillin materials were characterized by XRD, FT-IR and TGA analysis in order to evaluate the particle nature and size, the presence of functional groups and their thermal stability. The FESEM and EDAX analysis were performed to understand the surface morphology of the materials and the presence of CFNP in the material, respectively...
January 10, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28086263/observation-of-the-ring-puckering-vibrational-mode-in-thietane-cation
#4
Yu Ran Lee, Chung Bin Park, Jiye Hwang, Bongjune Sung, Hong Lae Kim, Chan Ho Kwon
We have measured the high-resolution vibrational spectra of a thietane (trimethylene sulfide) cation in the gas phase by employing the vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopic technique. Peaks in the low frequency region of the observed MATI spectrum of thietane originate from a progression of the ring puckering vibrational mode (typical in small heterocyclic molecules), which is successfully reproduced by quantum chemical calculations with one-dimensional (1D) symmetric double-well potentials along the ring puckering coordinates on both the S0 and D0 states, the ground electronic states of neutral and cation of thietane, respectively...
January 13, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28081534/enhanced-auditory-sensitivity-to-body-vibrations-in-superior-canal-dehiscence-syndrome
#5
Krister Brantberg, Luca Verrecchia, Magnus Westin
A key feature of superior canal dehiscence (SCD) syndrome is supranormal hearing of body sounds. The aim of the present study was to quantify this phenomenon and to ascertain whether auditory sensitivity to body vibrations can distinguish SCD patients. Hearing thresholds in response to vibration at the vertex, at the spinous process of the 7th cervical vertebra, and at the medial malleolus were tested in 10 SCD patients and 10 controls. Both patients and controls had insert earphones in both ears. The insert in the test ear was blocked while masking was presented to the other ear...
January 13, 2017: Audiology & Neuro-otology
https://www.readbyqxmd.com/read/28081493/optical-and-vibrational-properties-of-phosphorylcholine-based-contact-lenses-experimental-and-theoretical-investigations
#6
Katarzyna Filipecka, Rafał Miedziński, Maciej Sitarz, Jacek Filipecki, Małgorzata Makowska-Janusik
The Raman, MIR and UV-vis spectroscopy have been used to characterize Omafilcon A material constructing the one of the Proclear family contact lenses. The Omafilcon A is hydrogel material composed of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (PC) polymers crosslinked with ethyleneglycol dimethacrylate (EGDMA). Vibrational and electronic properties of the Omafilcon A material were also investigated by quantum chemical calculations. Experimentally obtained Raman, MIR and optical spectra were compared to the theoretical ones calculated applying RHF and DFT methodology...
January 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28081257/influence-of-la3-substitution-on-structure-morphology-and-magnetic-properties-of-nanocrystalline-ni-zn-ferrite
#7
Y K Dasan, B H Guan, M H Zahari, L K Chuan
Lanthanum substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5LaxFe1-xO4; 0.00 ≤x≤ 1.00) synthesized by sol-gel method were presented. X-ray diffraction patterns reveal the typical single phase spinel cubic ferrite structure, with the traces of secondary phase for lanthanum substituted nanocrystals. In addition, the structural analysis also demonstrates that the average crystallite size varied in the range of 21-25 nm. FTIR spectra present the two prominent absorption bands in the range of 400 to 600 cm-1 which are the fingerprint region of all ferrites...
2017: PloS One
https://www.readbyqxmd.com/read/28081187/perceptual-space-of-superimposed-dual-frequency-vibrations-in-the-hands
#8
Inwook Hwang, Jeongil Seo, Seungmoon Choi
The use of distinguishable complex vibrations that have multiple spectral components can improve the transfer of information by vibrotactile interfaces. We investigated the qualitative characteristics of dual-frequency vibrations as the simplest complex vibrations compared to single-frequency vibrations. Two psychophysical experiments were conducted to elucidate the perceptual characteristics of these vibrations by measuring the perceptual distances among single-frequency and dual-frequency vibrations. The perceptual distances of dual-frequency vibrations between their two frequency components along their relative intensity ratio were measured in Experiment I...
2017: PloS One
https://www.readbyqxmd.com/read/28081093/balanced-detection-for-self-mixing-interferometry
#9
Kun Li, Federico Cavedo, Alessandro Pesatori, Changming Zhao, Michele Norgia
We propose a new detection scheme for self-mixing interferometry using two photodiodes for implementing a differential acquisition. The method is based on the phase opposition of the self-mixing signal measured between the two laser diode facet outputs. The subtraction of the two outputs implements a sort of balanced detection that improves the signal quality, and allows canceling of unwanted signals due to laser modulation and disturbances on laser supply and transimpedance amplifier. Experimental results demonstrate the benefits of differential acquisition in a system for both absolute distance and displacement-vibration measurement...
January 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28080051/prediction-of-bond-dissociation-energies-heat-of-formation-for-diatomic-transition-metal-compounds-ccsd-t-works
#10
Zongtang Fang, Monica Vasiliu, Kirk A Peterson, David A Dixon
It was recently reported (J. Chem. Theory Comput. 2015, 11, 2036-2052) that the coupled cluster singles and doubles with perturbative triples method, CCSD(T), should not be used as a benchmark tool for the prediction of dissociation energies (heats of formation) for the 1st row transition metal diatomics based on a comparison with the experimental thermodynamic values for a set of 20 diatomics. In the present work the bond dissociation energies as well as the heats of formation for those diatomics have been calculated by the Feller-Peterson-Dixon approach at the CCSD(T)/complete basis set (CBS) level of theory including scalar relativistic corrections and correlation of the outer shell of core electrons in addition to the valence electrons...
January 12, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28080033/solvent-templated-folding-of-perylene-bisimide-macrocycles-into-coiled-double-string-ropes-with-solvent-sensitive-optical-signatures
#11
Peter Spenst, Ryan M Young, Brian T Phelan, Michel Keller, Jakub Dostál, Tobias Brixner, Michael R Wasielewski, Frank Würthner
A series of semi-rigid perylene bisimide (PBI) macrocycles with varied ring size containing two to nine PBI chromophores were synthesized in a one-pot reaction and their photophysical properties were characterized by fluorescence, steady-state and transient absorption spectroscopy as well as femtosecond stimulated Raman spectroscopy. These macrocycles show solvent-dependent conformational equilibria and excited-state properties. In dichloromethane the macrocycles prevail in wide-stretched conformations and exhibit upon photoexcitation symmetry-breaking charge separation followed by charge recombination to triplet states, which photosensitize singlet oxygen formation...
January 12, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28079969/molecular-polygons-probe-the-role-of-intramolecular-strain-in-the-photophysics-of-%C3%AF-conjugated-chromophores
#12
Philipp Wilhelm, Jan Vogelsang, Georgiy Poluektov, Nina Schönfelder, Tristan J Keller, Stefan-Sven Jester, Sigurd Höger, John M Lupton
π-Conjugated segments, chromophores, are the electronically active units of polymer materials used in organic electronics. To elucidate the effect of the bending of these linear moieties on elementary electronic properties, such as luminescence color and radiative rate, we introduce a series of molecular polygons. The π-system in these molecules becomes so distorted in bichromophores (digons) that these absorb and emit light of arbitrary polarization: any part of the chain absorbs and emits radiation with equal probability...
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28079958/an-s-oxygenated-nife-complex-modelling-sulfenate-intermediates-of-an-o2-tolerant-hydrogenase
#13
Nils J Lindenmaier, Stefan Wahlefeld, Eckhard Bill, Tibor Szilvási, Christopher Eberle, Shenglai Yao, Peter Hildebrandt, Marius Horch, Ingo Zebger, Matthias Driess
To understand the molecular details of O2 -tolerant hydrogen cycling by a soluble NAD(+) -reducing [NiFe] hydrogenase, we herein present the first bioinspired heterobimetallic S-oxygenated [NiFe] complex as a structural and vibrational spectroscopic model for the oxygen-inhibited [NiFe] active site. This compound and its non-S-oxygenated congener were fully characterized, and their electronic structures were elucidated in a combined experimental and theoretical study with emphasis on the bridging sulfenato moiety...
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28079923/vibrational-circular-dichroism-of-a-2-5-diketopiperazine-dkp-peptide-evidence-for-dimer-formation-in-cyclo-ll-or-ld-diphenylalanine-in-the-solid-state
#14
Ariel Pérez-Mellor, Anne Zehnacker
The diastereomer diketopiperazine (DKP) peptides built on phenylalanine, namely, cyclo diphenylalanine LPhe-LPhe and LPhe-DPhe, were studied in the solid phase by vibrational circular dichroism (VCD) coupled to quantum chemical calculations. The unit structure of cyclo LPhe-LPhe in KBr pellets is a dimer bridged by two strong NH…O hydrogen bonds. The intense bisignate signature in the CO stretch region is interpreted in terms of two contributions arising from the free COs of the dimer and the antisymmetrical combination of the bound COs...
January 12, 2017: Chirality
https://www.readbyqxmd.com/read/28079374/ultrafast-dynamics-of-hydrogen-bond-breaking-and-making-in-the-excited-state-of-fluoren-9-one-time-resolved-visible-pump-ir-probe-spectroscopic-study
#15
Rajib Ghosh, Aruna K Mora, Sukhendu Nath, Dipak K Palit
Fluoren-9-one (FL) molecule with a single hydrogen bond accepting site (C=O group) has been used as a probe for investigation of the dynamics of hydrogen bond in its lowest excited singlet (S1) state using subpicosecond time-resolved visible pump - IR probe spectroscopic technique. In hexafluoroisopropanol (HFIP), a strong hydrogen bond donating solvent, formation of FL-alcohol hydrogen bonded complex in the ground electronic (S0) state is nearly complete with negligible concentration of FL molecule remaining free in solution...
January 12, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28079372/effect-of-water-coordination-on-luminescent-properties-of-pyrazine-bridged-dinuclear-cu-i-complexes
#16
Atsushi Kobayashi, Ryuya Arata, Tomohiro Ogawa, Masaki Yoshida, Masako Kato
Two luminescent pyrazine-bridged dinuclear Cu(I) complexes, namely, [{Cu(PPh3)2(H2O)}(μ-MeOpyz){Cu(PPh3)2(CH3CN)}](BF4)2 and [{Cu(PPh3)2(H2O)}(μ-MeOpyz){Cu(PPh3)2(H2O)}](BF4)2 (H2O-Cu2-AN and H2O-Cu2-H2O; PPh3 = triphenylphosphine, MeOpyz = 2-methoxypyrazine), were successfully synthesized and characterized by single-crystal X-ray diffraction and luminescence measurements. X-ray analysis revealed that the water molecules are coordinated to both Cu(I) ions to form almost the same P2N1O1 coordination structure in H2O-Cu2-H2O, whereas one of the two Cu ions in H2O-Cu2-AN was coordinated by acetonitrile instead of water to form a different P2N2 coordination environment...
January 12, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28079277/whole-body-vibration-exposure-of-occupational-horseback-riding-in-agriculture-a-ranching-example
#17
Xiaoke Zeng, Catherine Trask, Aaron M Kociolek
BACKGROUND: Horse riding is common in many occupations; however, there is currently no research evaluating exposure to whole-body vibration and mechanical shock on horseback. METHODS: Whole-body vibration was measured on a cattle rancher during two 30 min horseback rides using a tri-axial accelerometer mounted on a western saddle. Vibration was summarized into standardized metrics, including the 8 hr equivalent root-mean-squared acceleration (A[8]) and the daily 4th power vibration dose value (VDV)...
February 2017: American Journal of Industrial Medicine
https://www.readbyqxmd.com/read/28079200/a-molecular-dynamics-study-of-the-interaction-of-water-with-the-external-surface-of-silicalite-1
#18
Konstantin S Smirnov
The interaction of water with the hydroxylated (010) surface of silicalite-1 was studied by classical molecular dynamics simulations. Interatomic interactions in the system were described using a set of effective potentials combining well-tested BKS and SPC models. The extended force field is shown to correctly reproduce the structural, energy, and dynamical characteristics of the silica surface OH groups. The interaction of water with the hydrophilic silanols leads to an ordering of H2O molecules in the vicinity of the surface...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28078764/photoisomerization-of-a-chiral-imine-molecular-switch-followed-by-matrix-isolation-vcd-spectroscopy
#19
Corina H Pollok, Tim Riesebeck, Christian Merten
Characterizing the stereochemistry of transient photoisomerization products remains a big challenge for the design of molecular machines, such as unidirectional molecular motors. Often these states are not stable long enough to be characterized in detail using conventional spectroscopic tools. The structurally simple camphorquinone imine 1 serves to illustrate the advantage of combining the matrix-isolation technique with vibrational circular dichroism (VCD) spectroscopy for the investigation of photoisomerizations of chiral molecules...
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28078392/carbon-footprint-assessment-of-western-australian-groundwater-recycling-scheme
#20
Andrew Simms, Stacey Hamilton, Wahidul K Biswas
This research has determined the carbon footprint or the carbon dioxide equivalent (CO2 eq) of potable water production from a groundwater recycling scheme, consisting of the Beenyup wastewater treatment plant, the Beenyup groundwater replenishment trial plant and the Wanneroo groundwater treatment plant in Western Australia, using a life cycle assessment approach. It was found that the scheme produces 1300 tonnes of CO2 eq per gigalitre (GL) of water produced, which is 933 tonnes of CO2 eq higher than the desalination plant at Binningup in Western Australia powered by 100% renewable energy generated electricity...
January 11, 2017: Environmental Management
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