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Sample records for stretching vibration band

  1. Vibrations of stretched damped beams under non-ideal boundary ...

    Indian Academy of Sciences (India)

    Stretched beam vibrations; non-ideal boundary conditions; method of multiple time scales. 1. Introduction. Beams are frequently used as design models for vibration analysis. In such analysis, types of support conditions are important and have direct effect on the solutions and natural fre- quencies. Different types of supports ...

  2. Vibrational spectroscopy of Cm–C/Cb–Cb stretching vibrations of ...

    Indian Academy of Sciences (India)

    operator which conveniently describes stretching vibrations of biomolecules. For a copper tetramesityl porphyrin molecule, the higher excited vibrational levels are calculated by applying the U(2) algebraic approach. Keywords. Lie algebraic techniques; vibrational spectra; copper tetramesityl porphyrin. PACS Nos 31.65.

  3. Comparing the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men.

    Science.gov (United States)

    Ferguson, Steven L; Kim, Eonho; Seo, Dong-Il; Bemben, Michael G

    2013-12-01

    This study compared the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men. Twenty-one men were randomly assigned to vibration-stretching (VS; n = 8), vibration only (VO; n = 6), or stretching only (SO; n = 7) groups that trained 3 times per week for 3 weeks. All 3 groups performed 9 total sets of 30-second stretches. The VS group performed four 30-second upper-body vibration exercises and five 30-second upper-body stretching exercises. The VO group performed nine 30-second upper-body vibration exercises. The SO group performed nine 30-second upper-body stretching exercises. Shoulder flexion (SF), shoulder extension (SE), and shoulder transverse extension (STE) were assessed by a Leighton Flexometer and back scratch tests bilaterally (BSR, BSL) were measured via tape measure. A 1-way analysis of variance (ANOVA) evaluated groups at baseline and a 2-way repeated-measures ANOVA evaluated the interventions over time. At baseline, there were no group differences in age, height, or weight. There was a significant (p alone or combined with stretching, is a viable alternative to a standard stretching routine when attempting to increase shoulder flexibility. Adding vibration training to a flexibility regimen may improve the likelihood of regularly performing flexibility sessions because of increased variety.

  4. The acute effects of stretching with vibration on dynamic flexibility in young female gymnasts.

    Science.gov (United States)

    Johnson, Aaron W; Warcup, Caisa N; Seeley, Matthew K; Eggett, Dennis; Feland, Jeffery B

    2018-01-10

    While stretching with vibration has been shown to improve static flexibility; the effect of stretching with vibration on dynamic flexibility is not well known. The purpose of this study was to examine the effectiveness of stretching with vibration on acute dynamic flexibility and jump height in novice and advanced competitive female gymnasts during a split jump. Female gymnast (n=27, age: 11.5 ± 1.7 years, Junior Olympic levels 5-10) participated in this cross-over study. Dynamic flexibility during gymnastic split jumps were video recorded and analyzed with Dartfish software. All participants completed both randomized stretching protocols with either the vibration platform turned on (VIB) (frequency of 30 Hz and 2 mm amplitude) or off (NoVIB) separated by 48 h. Participants performed 4 sets of three stretches on the vibration platform. Each stretch was held for 30 s with 5 s rest for a total of 7 min of stretch. Split jump flexibility decreased significantly from pre to post measurement in both VIB (-5.8°±5.9°) (pstatic stretching with or without vibration immediately before performance does not alter jump height. Stretching with vibration immediately prior to gymnastics competition decreases split jump flexibility in lower level gymnasts more than upper level gymnasts.

  5. Theoretical study of the C-H/O-H stretching vibrations in malonaldehyde

    Science.gov (United States)

    Pitsevich, G. A.; Malevich, A. E.; Kozlovskaya, E. N.; Doroshenko, I. Yu.; Pogorelov, V. E.; Sablinskas, V.; Balevicius, V.

    2015-06-01

    IR and Raman spectra of the malonaldehyde molecule and its deuterated analogues were calculated in the B3LYP/cc-pVQZ approximation. Anharmonicity effects were taken into account both in the context of a standard model of the second order perturbation theory and by constructing the potential energy surfaces (PES) with a limited number of dimensions using the Cartesian coordinates of the hydroxyl hydrogen atom and the stretching coordinates of С-Н, C-D, O-H, and O-D bonds. It was shown that in each of the two equivalent forms of the molecule, besides the global minimum, an additional local minimum at the PES is formed with the energy more than 3000 cm-1 higher than the energy in the global minimum. Calculations carried out by constructing the 2D and 3D PESs indicate a high anharmonicity level and multiple manifestations of the stretching О-Н vibrations, despite the fact that the model used does not take into account the splitting of the ground-state and excited vibrational energy levels. In particular, the vibration with the frequency 3258 cm-1 may be associated with proton transfer to the region of a local minimum of energy. Comparing the results obtained with the experimental data presented in the literature allowed us to propose a new variant of bands assignments in IR and Raman spectra of the molecule in the spectral region 2500-3500 cm-1.

  6. Does vibration counteract the static stretch-induced deficit on muscle force development?

    Science.gov (United States)

    Fernandes, Igor Alexandre; Kawchuk, Gregory; Bhambhani, Yagesh; Gomes, Paulo Sergio Chagas

    2013-09-01

    To determine the residual acute vibration-stretching effect on preactivation levels, short-latency stretch reflex, and performance during execution of drop jumps. Repeated measures. Eleven male recreational athletes performed a set of three 45cm drop jumps before and immediately after a 30s static stretching exercise with and without simultaneously imposed muscle vibration (45Hz, 5mm). Drop jump height, ground reaction forces and electromyographic data including Vastus Lateralis onset/levels of preactivation and short-latency stretch reflex were recorded. No changes were induced on drop jump height. However, stretching-induced decrements on ground reaction force peak and time to peak as well as an increment in contact time followed a delay in short-latency stretch reflex onset and a reduced preactivation level of Vastus Lateralis. Otherwise, when vibration was simultaneously imposed, there was no evidence of changes in high-speed force production variables or electromyographic recordings. Mechanical vibration, when applied simultaneously to static-stretching routines, appeared to be effective to counteract decreased musculotendinous unit stiffness-induced high-speed force production deficit during jumping performance. Copyright © 2012. Published by Elsevier Ltd.

  7. Warm-up effects from concomitant use of vibration and static stretching after cycling.

    Science.gov (United States)

    Yang, Wen-Wen; Liu, Chiang; Shiang, Tzyy-Yuang

    2017-04-01

    Static stretch is routinely used in traditional warm-up but impaired muscle performance. Combining vibration with static stretching as a feasible component may be an alternative to static stretching after submaximal aerobic exercise to improve jumping as well as flexibility. Therefore, the purpose of this study was to investigate and compare the effects of aerobic exercise, static stretching, and vibration with static stretching on flexibility and vertical jumping performance. A repeated measures experimental design was used in this study. Twelve participants randomly underwent 5 different warm-ups including cycling alone (C warm-up), static stretching alone (S warm-up), combining vibration with static stretching (VS warm-up), cycling followed by S (C+S warm-up), and cycling followed by VS (C+VS warm-up) on 5 separate days. Sit-and-reach, squat jump (SJ), and counter movement jump (CMJ) were measured for pre- and post- tests. The sit-and-reach scores after the S, VS, C+S and C+VS warm-ups were significantly enhanced (Pafter the C and C+VS warm-ups were significantly increased (Pafter the S warm-up (Pstretching after submaximal cycling exercise (C+VS warm-up) could be a feasible warm-up protocol to improve both flexibility and vertical jump performance, compared with the traditional warm-up (C+S warm-up).

  8. Vibrational spectroscopy of triacetone triperoxide (TATP): Anharmonic fundamentals, overtones and combination bands

    Science.gov (United States)

    Brauer, Brina; Dubnikova, Faina; Zeiri, Yehuda; Kosloff, Ronnie; Gerber, R. Benny

    2008-12-01

    The vibrational spectrum of triacetone triperoxide (TATP) is studied by the correlation-corrected vibrational self-consistent field (CC-VSCF) method which incorporates anharmonic effects. Fundamental, overtone, and combination band frequencies are obtained by using a potential based on the PM3 method and yielding the same harmonic frequencies as DFT/cc-pVDZ calculations. Fundamentals and overtones are also studied with anharmonic single-mode (without coupling) DFT/cc-pVDZ calculations. Average deviations from experiment are similar for all methods: 2.1-2.5%. Groups of degenerate vibrations form regions of numerous combination bands with low intensity: the 5600-5800 cm -1 region contains ca. 70 overtones and combinations of CH stretches. Anharmonic interactions are analyzed.

  9. Acute static vibration-induced stretching enhanced muscle viscoelasticity but did not affect maximal voluntary contractions in footballers.

    Science.gov (United States)

    Jemni, Monèm; Mkaouer, Bessem; Marina, Michel; Asllani, Arben; Sands, William A

    2014-11-01

    The aim of this study was to compare the effects of acute vibration-enhanced static stretching and/or static stretching alone on the strength and flexibility of the hamstrings and quadriceps muscles. Twenty-one male footballers participated in this study (21.9 ± 1.8 years; 75.54 ± 7.3 kg; 178.7 ± 6.5 cm). The experiment started with 5 minutes standardized warm-up followed by (a) baseline flexibility pretest (Split Test); (b) maximal voluntary flexion and extension (isokinetic strength) of the knee; (c) Treatment or Sham involving 45-second stretch with or without vibration for the hamstring and quadriceps muscle groups with 10-second rest between; and (d) posttest repeating the measures of the pretest. Each player randomly performed both trials on separate occasions. The vibration device operated at 35 Hz with 2 mm amplitude. Stretching with vibration statistically increased hamstring flexibility by 7.8% (p ≤ 0.05) when compared with stretching without vibration. No statistical differences for hamstring or quadriceps strength were noted between treatment conditions. There was no statistical correlation between flexibility and strength measurements. In conclusion, flexibility increased with vibration-enhanced static stretching; however, no change was evident in the maximal voluntary contractions of the knee flexors and extensors.

  10. Vibrational Coupling Pathways in the CH Stretch Region of CH_3OH and CH_3OD as Revealed by IR and Ftmw-Ir Spectroscopies

    Science.gov (United States)

    Twagirayezu, Sylvestre; Wang, Xiaoliang; Perry, David S.; Neill, Justin L.; Muckle, Matt T.; Pate, Brooks H.; Xu, Li-Hong

    2011-06-01

    Infrared spectra of jet-cooled CH_3OD and CH_3OH in the CH stretch region are observed by coherence-converted population transfer Fourier transform microwave-infrared (CCPT-FTMW-IR) spectroscopy (E torsional species only) and by slit-jet single resonance spectroscopy (both A and E torsional species, CH_3OH only). Previously, we reported the analysis of ν_3 symmetric CH stretch region (2750-2900 Cm-1), and the present work extends the analysis to higher frequency (2900-3020 Cm-1). The overall observed spectra contain 17 interacting vibrational bands for CH_3OD and 28 for CH_3OH. The signs and magnitudes of the torsional tunneling splittings are deduced for three CH fundamentals (ν_3, ν_9, ν_2) of both molecules and are compared to a model calculation and to ab initio theory. The number and distribution of observed vibrational bands indicate that the CH stretch bright states couple first to doorway states that are binary combinations of bending modes. In the parts of the spectrum where doorway states are present, the observed density of coupled states is comparable to the total density of vibrational states in the molecule, but where there are no doorway states, only the CH stretch fundamentals are observed. A time-dependent interpretation of the present FTMW-IR spectra indicates a fast (˜ 200 fs) initial decay of the bright state followed by second, slower redistribution (˜ 1-3 ps). The qualitative agreement of the present data with the time-dependent experiments of Iwaki and Dlott provides further support for the similarity of the fastest vibrational relaxation processes in the liquid and gas phases. Twagirayezu, S.; Clasp, T. N.; Perry, D. S.; Neill, J. L.; Muckle, M. T.; Pate, B. H. J. Phys. Chem. A 2010, 114, 6818 Iwaki, L. K.; Dlott, D. D. J. Phys. Chem. A 2000, 104, 9101

  11. Spectrum of OH-stretching vibrations of water in a "floating" water bridge

    Science.gov (United States)

    Oshurko, V. B.; Ropyanoi, A. A.; Fedorov, A. N.; Fedosov, M. V.; Shelaeva, N. A.

    2012-11-01

    The axial distribution (over the cross section) of the spectra of the OH-stretching band of water in a water bridge is investigated using the Raman scattering method. It is found that the axial structure of the bridge is inhomogeneous: the core at the center of the bridge contains a larger amount of water with an "icelike" structure and a presumably larger number of H+ ions, while the outer layer probably consists of water with a larger number of OH- ions.

  12. Fatigue failure of materials under narrow band random vibrations. I.

    Science.gov (United States)

    Huang, T. C.; Hubbard, R. B.; Lanz, R. W.

    1971-01-01

    A novel approach for the study of fatigue failure of materials under the multifactor influence of narrow band random vibrations is developed. The approach involves the conduction of an experiment in conjunction with various statistical techniques. Three factors including two statistical properties of the excitation or response are considered and varied simultaneously. A minimum of 6 tests for 3 variables is possible for a fractional f actorial design. The four coefficients of the predicting equation can be independently estimated. A look at 3 predicting equations shows the predominant effect of the root mean square stress of the first order equation.

  13. Vibrational dephasing of the C-Br stretching modes in gauche and trans dibromoethane

    Science.gov (United States)

    Schwartz, M.; Moradi-Araghi, A.; Koehler, W. H.

    The isotropic Raman spectra of the gauche and trans C-Br stretching modes in 1,2-dibromoethane were studied as a function of temperature in the liquid phase. Isotropic dephasing times were found to be longer for the gauche conformer, and decreased at higher temperatures for both rotamers. Vibrational second moments were observed to be greater for the trans species. Application of the isolated binary collision model to this system could not reproduce the experimentally observed temperature dependence of τiso. Values of the modulation times obtained from the Kubo lineshape formalism are in qualitative agreement with Enskog hard-sphere collision times. This approach was also used to provide a qualitative explanation of the longer observed modulation times in the gauche conformer.

  14. Modeling Stretching Modes of Common Organic Molecules with the Quantum Mechanical Harmonic Oscillator: An Undergraduate Vibrational Spectroscopy Laboratory Exercise

    Science.gov (United States)

    Parnis, J. Mark; Thompson, Matthew G. K.

    2004-01-01

    An introductory undergraduate physical organic chemistry exercise that introduces the harmonic oscillator's use in vibrational spectroscopy is developed. The analysis and modeling exercise begins with the students calculating the stretching modes of common organic molecules with the help of the quantum mechanical harmonic oscillator (QMHO) model.

  15. Stretching dependence of the vibration modes of a single-molecule Pt-H-2-Pt bridge

    DEFF Research Database (Denmark)

    Djukic, D.; Thygesen, Kristian Sommer; Untiedt, C.

    2005-01-01

    isotope substitution is obtained. The stretching dependence for each of the modes allows uniquely classifying them as longitudinal or transversal modes. The interpretation of the experiment in terms of a Pt-H-2-Pt bridge is verified by density-functional theory calculations for the stability, vibrational...

  16. Cytotoxicity Comparison of the Nanoparticles Deposited on Latex Rubber Bands between the Original and Stretched State

    Directory of Open Access Journals (Sweden)

    Jung-Hwan Lee

    2014-01-01

    Full Text Available Understanding the biocompatibility of nanoparticles in dental materials is essential for their safe usage in the oral cavity. In this study, we investigated whether nanoparticles deposited on orthodontic latex rubber bands are involved in the induction of cytotoxicity. A method of stretching to three times (“3L” the length of the latex rubber bands was employed to detach the particles using the original length (“L” for comparison. The cytotoxicity tests were performed on extracts with mouse fibroblasts (L929 and human gingival fibroblasts (HGFs. Fourier transform infrared spectroscopy, ion chromatography, elemental analysis, and inductively coupled plasma mass spectrometry (ICP-MS were performed to detect the harmful components in the extracts from rubber bands. There was a significant decrease in the cell viability in the “L” samples compared with the “3L” samples (P<0.05 in the L929 and HGF cells. This was due to the Ni single crystal nanoparticles (~50nm from the inner surface of “L” samples that were detached in the “3L” samples as well as the Zn ion (~9 ppm detected in the extract. This study revealed that the Ni nanoparticles, as well as Zn ions, were involved in the induction of cytotoxicity from the latex rubber bands.

  17. Torsion-rotation structure and quasi-symmetric-rotor behaviour for the CH3SH asymmetric CH3-bending and C-H stretching bands of E parentage

    Science.gov (United States)

    Lees, R. M.; Xu, Li-Hong; Guislain, B. G.; Reid, E. M.; Twagirayezu, S.; Perry, D. S.; Dawadi, M. B.; Thapaliya, B. P.; Billinghurst, B. E.

    2018-01-01

    High-resolution Fourier transform spectra of the asymmetric methyl-bending and methyl-stretching bands of CH3SH have been recorded employing synchrotron radiation at the FIR beamline of the Canadian Light Source. Analysis of the torsion-rotation structure and relative intensities has revealed the novel feature that for both bend and stretch the in-plane and out-of-plane modes behave much like a Coriolis-coupled l-doublet pair originating from degenerate E modes of a symmetric top. As the axial angular momentum K increases, the energies of the coupled "l = ±1" modes diverge linearly, with effective Coriolis ζ constants typical for symmetric tops. For the methyl-stretching states, separated at K = 0 by only about 1 cm-1, the assigned sub-bands follow a symmetric top Δ(K - l) = 0 selection rule, with only ΔK = -1 transitions observed to the upper l = -1 in-plane A‧ component and only ΔK = +1 transitions to the lower l = +1 out-of-plane A″ component. The K = 0 separation of the CH3-bending states is larger at 9.1 cm-1 with the l-ordering reversed. Here, both ΔK = +1 and ΔK = -1 transitions are seen for each l-component but with a large difference in relative intensity. Term values for the excited state levels have been fitted to J(J + 1) power-series expansions to obtain substate origins. These have then been fitted to a Fourier model to characterize the torsion-K-rotation energy patterns. For both pairs of vibrational states, the torsional energies display the customary oscillatory behaviour as a function of K and have inverted torsional splittings relative to the ground state. The spectra show numerous perturbations, indicating local resonances with the underlying bath of high torsional levels and vibrational combination and overtone states. The overall structure of the two pairs of bands represents a new regime in which the vibrational energy separations, torsional splittings and shifts due to molecular asymmetry are all of the same order, creating a

  18. Effect of hydrogen bonding on the infrared absorption intensity of OH stretch vibrations

    Science.gov (United States)

    Athokpam, Bijyalaxmi; Ramesh, Sai G.; McKenzie, Ross H.

    2017-05-01

    We consider how the infrared intensity of a hydrogen-bonded OH stretch varies from weak to strong H-bonds using a theoretical model. We obtain trends for the fundamental and overtone transition intensities as a function of the donor-acceptor distance, a common measure of H-bond strength. Building upon our earlier work using a two-diabatic state model, we introduce a Mecke function-based dipole moment for the H-bond and calculate transition moments using one-dimensional vibrational eigenstates along the H-atom transfer coordinate. The fundamental intensity is found to be over 20-fold enhanced for strong H-bonds, where non-Condon effects are significant. We analyse isotope effects, including the secondary geometric isotope effect. The first overtone intensity varies non-monotonically with H-bond strength; suppression occurs for weak bonds but strong enhancements are possible for strong H-bonds. We also study how these trends are affected by Mecke parameter variations. For a few specific dimers, we compare our results with earlier works.

  19. Complete flexural vibration band gaps in membrane-like lattice structures

    International Nuclear Information System (INIS)

    Yu Dianlong; Liu Yaozong; Qiu Jing; Wang Gang; Zhao Honggang

    2006-01-01

    The propagation of flexural vibration in the periodical membrane-like lattice structure is studied. The band structure calculated with the plane wave expansion method indicates the existence of complete gaps. The frequency response function of a finite periodic structure is simulated with finite element method. Frequency ranges with vibration attenuation are in good agreement with the gaps found in the band structure. Much larger attenuations are found in the complete gaps comparing to those directional ones. The existence of complete flexural vibration gaps in such a lattice structure provides a new idea for vibration control of thin plates

  20. Alternative to traditional stretching methods for flexibility enhancement in well-trained combat athletes: local vibration versus whole-body vibration

    Science.gov (United States)

    2015-01-01

    This study aimed to compare the effect of local vibration (LV) and whole body vibration (WBV) on lower body flexibility and to assess whether vibration treatments were more effective than traditionally used static and dynamic stretching methods. Twenty-four well-trained male combat athletes (age: 22.7 ± 3.3 years) performed four exercise protocols – LV (30 Hz, 4 mm), WBV (30 Hz, 4 mm), static stretching (SS), and dynamic stretching (DS) – in four sessions of equal duration 48 hours apart in a randomized, balanced order. During a 15-minute recovery after each protocol, subjects performed the stand and reach test (S&R) at the 15th second and the 2nd, 4th, 6th, 8th, 10th and 15th minute. There was a similar change pattern in S&R scores across the 15-minute recovery after each protocol (p = 0.572), remaining significantly elevated throughout the recovery. A significant main protocol effect was found for absolute change in S&R scores relative to baseline (p = 0.015). These changes were statistically greater in LV than WBV and DS. Changes in SS were not significantly different from LV, but were consistently lower than LV with almost moderate effect sizes. After LV, a greater percentage of subjects increased flexibility above the minimum detectable change compared to other protocols. Subjects with high flexibility (n = 12) benefited more from LV compared with other methods (effect size ≥ 0.862). In conclusion, LV was an effective alternative exercise modality to acutely increase lower extremity flexibility for well-trained athletes compared with WBV and traditional stretching exercises. PMID:26424926

  1. Systematics of the K suppi = 2+ gamma vibrational bands and odd-even staggering

    CERN Document Server

    Gupta, J B

    2003-01-01

    The structure of the K suppi = 2+ gamma vibrational bands and the quasi-gamma bands of even-Z-even-N nuclei is investigated on a global scale, vis-a-vis the variation of band head, the moment of inertia of the band and the odd-even spin staggering. The variation with N and Z and with spin J of the odd-even spin energy staggering index is studied and a unified view of the same is presented. (author)

  2. Dispersion Relation of an OH-Stretching Vibration from Inelastic X-Ray Scattering

    Science.gov (United States)

    Winkler, Björn; Friedrich, Alexandra; Wilson, Dan J.; Haussühl, Eiken; Krisch, Michael; Bosak, Alexei; Refson, Keith; Milman, Victor

    2008-08-01

    We show that recent advances now allow us to measure the wave vector dependence of OH-stretching frequencies at energies around 400 meV by inelastic x-ray scattering using ID28@ESRF. We found a large, unexpected dispersion when we measured the dispersion relations of the hydrogen stretching frequencies of diaspore, α-AlOOH, where the hydrogen atoms participate in a hydrogen bond of intermediate strength. We can account for this behavior with density functional perturbation theory calculations and a simple model based on H-H interactions.

  3. Low-frequency band gap mechanism of torsional vibration of lightweight elastic metamaterial shafts

    Science.gov (United States)

    Li, Lixia; Cai, Anjiang

    2016-07-01

    In this paper, the low-frequency band gap mechanism of torsional vibration is investigated for a kind of light elastic metamaterial (EM) shafts architecture comprised of a radial double-period element periodically as locally resonant oscillators with low frequency property. The dispersion relations are calculated by a method combining the transfer matrix and a lumped-mass method. The theoretical results agree well with finite method simulations, independent of the density of the hard material ring. The effects of the material parameters on the band gaps are further explored numerically. Our results show that in contrast to the traditional EM shaft, the weight of our proposed EM shaft can be reduced by 27% in the same band gap range while the vibration attenuation is kept unchanged, which is very convenient to instruct the potential engineering applications. Finally, the band edge frequencies of the lower band gaps for this light EM shaft are expressed analytically using physical heuristic models.

  4. Vibrational renormalisation of the electronic band gap in hexagonal and cubic ice

    Energy Technology Data Exchange (ETDEWEB)

    Engel, Edgar A., E-mail: eae32@cam.ac.uk; Needs, Richard J. [TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Monserrat, Bartomeu [TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019 (United States)

    2015-12-28

    Electron-phonon coupling in hexagonal and cubic water ice is studied using first-principles quantum mechanical methods. We consider 29 distinct hexagonal and cubic ice proton-orderings with up to 192 molecules in the simulation cell to account for proton-disorder. We find quantum zero-point vibrational corrections to the minimum electronic band gaps ranging from −1.5 to −1.7 eV, which leads to improved agreement between calculated and experimental band gaps. Anharmonic nuclear vibrations play a negligible role in determining the gaps. Deuterated ice has a smaller band-gap correction at zero-temperature of −1.2 to −1.4 eV. Vibrations reduce the differences between the electronic band gaps of different proton-orderings from around 0.17 eV to less than 0.05 eV, so that the electronic band gaps of hexagonal and cubic ice are almost independent of the proton-ordering when quantum nuclear vibrations are taken into account. The comparatively small reduction in the band gap over the temperature range 0 − 240 K of around 0.1 eV does not depend on the proton ordering, or whether the ice is protiated or deuterated, or hexagonal, or cubic. We explain this in terms of the atomistic origin of the strong electron-phonon coupling in ice.

  5. Reconfigurable, Wideband Radar Transceiver and Antenna for P-band Stretch Processing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — IAI proposes to develop a Reconfigurable Wideband Radar Transceiver, with direct digital synthesis of P-band radar frequencies, novel high bandwidth P-band antenna...

  6. Vibration Therapy Is No More Effective Than the Standard Practice of Massage and Stretching for Promoting Recovery From Muscle Damage After Eccentric Exercise.

    Science.gov (United States)

    Fuller, Joel T; Thomson, Rebecca L; Howe, Peter R C; Buckley, Jonathan D

    2015-07-01

    The purpose of this study was to determine if vibration therapy is more effective than the standard treatment of stretching and massage for improving recovery of muscle strength and reducing muscle soreness after muscle damage induced by eccentric exercise. A randomized, single-blinded parallel intervention trial design was used. Research laboratory. Fifty untrained men aged 18 to 30 years completed the study. Participants performed 100 maximal eccentric muscle actions (ECCmax) of the right knee extensor muscles. For the next 7 days, 25 participants applied cycloidal vibration therapy to the knee extensors twice daily and 25 participants performed stretching and sports massage (SSM) twice daily. Changes in markers of muscle damage [peak isometric torque (PIT), serum creatine kinase (CK), and serum myoglobin (Mb)], muscle soreness (visual analog scale), and inflammation [serum C-reactive protein (CRP)] were assessed. After ECCmax, there was no difference in recovery of PIT and muscle soreness or serum CK, Mb, and CRP levels between vibration and SSM groups (P > 0.28). Cycloidal vibration therapy is no more effective than the standard practice of stretching and massage to promote muscle recovery after the performance of muscle-damaging exercise. Prescription of vibration therapy after maximal exercise involving eccentric muscle damage did not alleviate signs and symptoms of muscle damage faster than the standard prescription of stretching and massage.

  7. Fatigue failure of materials under broad band random vibrations

    Science.gov (United States)

    Huang, T. C.; Lanz, R. W.

    1971-01-01

    The fatigue life of material under multifactor influence of broad band random excitations has been investigated. Parameters which affect the fatigue life are postulated to be peak stress, variance of stress and the natural frequency of the system. Experimental data were processed by the hybrid computer. Based on the experimental results and regression analysis a best predicting model has been found. All values of the experimental fatigue lives are within the 95% confidence intervals of the predicting equation.

  8. Vibration-rotation bands of CH in the solar infrared spectrum and the solar carbon abundance

    NARCIS (Netherlands)

    Grevesse, N.; Lambert, D.L.; Sauval, A.J.; Dishoeck, van E.F.; Farmer, C.B.; Norton, R.H.

    1991-01-01

    High resolution solar spectra obtained from the ATMOS Fourier Transform Spectrometer (Spacelab 3 flight on April 29-May 6, 1985) have made it possible to identify and measure a large number of lines of the vibration-rotation fundamental bands of the X2 Pi state of CH. From about 100 lines of the

  9. Phononic band gaps and vibrations in one- and two-dimensional mass-spring structures

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    2003-01-01

    The vibrational response of finite periodic lattice structures subjected to periodic loading is investigated. Special attention is devoted to the response in frequency ranges with gaps in the band structure for the corresponding infinite periodic lattice. The effects of boundaries, viscous dampin...

  10. Resonance Raman studies of Co-O2 and O-O stretching vibrations in oxy-cobalt hemes.

    Science.gov (United States)

    Mackin, H C; Tsubaki, M; Yu, N T

    1983-03-01

    Strong evidence suggests that the stretching vibration of the bound oxygen can be perturbed by an accidentally degenerate porphyrin ring mode, resulting in two split frequencies. In the Co(II)(TpivPP) (pyridine) (18)O(2) complex, we demonstrate that the nu((18)O-(18)O) mode, after being shifted from its nu((16)O-(16)O) value at 1,156 cm(-1), undergoes a resonance interaction with the 1,080 cm(-1) porphyrin mode, giving rise to two lines at 1,067 and 1,089 cm(-1). In the O(2) complex of Co(II) mesoporphyrin IX-substituted sperm whale myoglobin, we observed a dramatic intensity increase at 1,132 cm(-1) upon (16)O(2) --> (18)O(2) substitution, which is due to the reappearance of the 1,132-cm(-1) porphyrin mode after the removal of resonance conditions. A decrease in O(2) binding affinity, caused by the proximal base tension, corresponds to an increase in the Co-O(2) stretching frequency. The nu(Co-O(2)) at 527 cm(-1) for the low affinity Co(II)(TpivPP)(1,2-Me(2)Im) O(2) complex is 11 cm(-1) higher than the 516-cm(-1) value for the high affinity complex (with N-MeIm replacing 1,2-Me(2)Im). However, in the corresponding iron complexes the reverse behavior is observed, i.e., the nu(Fe-O(2)) decreases for the (1,2-Me(2)Im) complex. There is a 24-cm(-1) difference in the Co-O(2) stretching frequencies between Co(II)(TpivPP)(N-MeIm)O(2) (at 516 cm(-1)) and oxy meso CoMb (at 540 cm(-1)), suggesting a protein induced distortion of the Co-O-O linkage. However, the values for nu(Fe-O(2)) are nearly identical between Fe(II)(TpivPP)(N-MeIm)O(2) (at 571 cm(-1)) and oxy Mb (at 573 cm(-1)), indicating that O(2) binds to myoglobin in the same manner as in the sterically unhindered "picket fence" complex. Evidence is presented that suggests the presence of two dioxygen stretching frequencies due to two different conformers in each of the N-MeIm and 1,2-Me(2)Im complex of oxy Co(II)(TpivPP).

  11. Resonance Raman Studies of Co—O2 and O—O Stretching Vibrations in Oxy-Cobalt Hemes

    Science.gov (United States)

    Mackin, Helen C.; Tsubaki, Motonari; Yu, Nai-Teng

    1983-01-01

    Strong evidence suggests that the stretching vibration of the bound oxygen can be perturbed by an accidentally degenerate porphyrin ring mode, resulting in two split frequencies. In the Co(II)(TpivPP) (pyridine) 18O2 complex, we demonstrate that the ν(18O—18O) mode, after being shifted from its ν(16O—16O) value at 1,156 cm-1, undergoes a resonance interaction with the 1,080 cm-1 porphyrin mode, giving rise to two lines at 1,067 and 1,089 cm-1. In the O2 complex of Co(II) mesoporphyrin IX-substituted sperm whale myoglobin, we observed a dramatic intensity increase at 1,132 cm-1 upon 16O2 → 18O2 substitution, which is due to the reappearance of the 1,132-cm-1 porphyrin mode after the removal of resonance conditions. A decrease in O2 binding affinity, caused by the proximal base tension, corresponds to an increase in the Co—O2 stretching frequency. The ν(Co—O2) at 527 cm-1 for the low affinity Co(II)(TpivPP)(1,2-Me2Im) O2 complex is 11 cm-1 higher than the 516-cm-1 value for the high affinity complex (with N-MeIm replacing 1,2-Me2Im). However, in the corresponding iron complexes the reverse behavior is observed, i.e., the ν(Fe—O2) decreases for the (1,2-Me2Im) complex. There is a 24-cm-1 difference in the Co—O2 stretching frequencies between Co(II)(TpivPP)(N-MeIm)O2 (at 516 cm-1) and oxy meso CoMb (at 540 cm-1), suggesting a protein induced distortion of the Co—O—O linkage. However, the values for ν(Fe—O2) are nearly identical between Fe(II)(TpivPP)(N-MeIm)O2 (at 571 cm-1) and oxy Mb (at 573 cm-1), indicating that O2 binds to myoglobin in the same manner as in the sterically unhindered “picket fence” complex. Evidence is presented that suggests the presence of two dioxygen stretching frequencies due to two different conformers in each of the N-MeIm and 1,2-Me2Im complex of oxy Co(II)(TpivPP). PMID:6838973

  12. Simultaneous spectral and temporal analyses of kinetic energies in nonequilibrium systems: theory and application to vibrational relaxation of O-D stretch mode of HOD in water.

    Science.gov (United States)

    Jeon, Jonggu; Lim, Joon Hyung; Kim, Seongheun; Kim, Heejae; Cho, Minhaeng

    2015-05-28

    A time series of kinetic energies (KE) from classical molecular dynamics (MD) simulation contains fundamental information on system dynamics. It can also be analyzed in the frequency domain through Fourier transformation (FT) of velocity correlation functions, providing energy content of different spectral regions. By limiting the FT time span, we have previously shown that spectral resolution of KE evolution is possible in the nonequilibrium situations [Jeon and Cho, J. Chem. Phys. 2011, 135, 214504]. In this paper, we refine the method by employing the concept of instantaneous power spectra, extending it to reflect an instantaneous time-correlation of velocities with those in the future as well as with those in the past, and present a new method to obtain the instantaneous spectral density of KE (iKESD). This approach enables the simultaneous spectral and temporal resolution of KE with unlimited time precision. We discuss the formal and novel properties of the new iKESD approaches and how to optimize computational methods and determine parameters for practical applications. The method is specifically applied to the nonequilibrium MD simulation of vibrational relaxation of the OD stretch mode in a hydrated HOD molecule by employing a hybrid quantum mechanical/molecular mechanical (QM/MM) potential. We directly compare the computational results with the OD band population relaxation time profiles extracted from the IR pump-probe measurements for 5% HOD in water. The calculated iKESD yields the OD bond relaxation time scale ∼30% larger than the experimental value, and this decay is largely frequency-independent if the classical anharmonicity is accounted for. From the integrated iKESD over intra- and intermolecular bands, the major energy transfer pathways were found to involve the HOD bending mode in the subps range, then the internal modes of the solvent until 5 ps after excitation, and eventually the solvent intermolecular modes. Also, strong hydrogen

  13. Hybrid Method for Analyzing the Torsional Vibration of One-Dimensional Phononic-Band-Gap Shafts

    Science.gov (United States)

    Li, Lixia; Chen, Tianning; Wu, Jiuhui; Wang, Xiaopeng; Wang, Zhaofeng

    2012-05-01

    A hybrid method combining the transfer-matrix and lumped-mass methods is proposed to study the band gaps of torsional vibration in one-dimensional (1D) phononic band gap (PBG)-like shafts, which periodically arrange local resonant multilayer rings. The present method shows advantages over the transfer-matrix and lumped-mass methods for determining the inertia of rubber rings and fast convergence with less computational requirements. For light local resonators, the torsional band gaps, which were studied in three 1D PBG-like shafts by the hybrid method, agree well with those studied by the finite method. In addition, more precise evaluations of the starting frequency of the band gaps were carried out analytically. The methodology of the approach presented can also be employed to study the band gaps of bending and longitudinal waves.

  14. Electrical anharmonicity and dampings contributions to Cl-H → stretching band in gaseous (CH3)2O…HCl complex: Quantum dynamic study and prediction of the temperature effects

    Science.gov (United States)

    Rekik, Najeh; Alshammari, Majid F.

    2017-06-01

    In a previous work (Rekik et al., 2017), we demonstrated the ability of a simple anharmonic model of the dipole moment function of the X-H stretching band to explain a set of spectroscopic features of hydrogen bonding formation. Within the context of this model, we have shown that the origins of the broadening of the X - H → stretching band is attributed to large terms in the expansion of the autocorrelation functions due to the electrical anharmonicity. However, the question remained as to the ability of this model to treat the more complex situation in which we take into account the relaxation mechanisms that look at the effect of the surroundings and thereby gives rise to signatures of the medium to the X - H → stretching band lineshapes. Thus, in the present study, we investigated this situation by envisaging that the direct relaxation mechanism is due to the coupling between the fluctuating local electric field and the dipole moment of the complex as rationalized by Rosh and Ratner and the indirect damping resulting from the interaction of the X - H → stretch with its environment via the H-bond bridge mode. Theoretical experiments show that mixing of all these effects results in a speard and complicated structure. Using an ensemble of physically sound parameters as input into this approach, we have captured the main features in the experimental Cl - H → band in gaseous (CH3)2O…HCl complex and shown that the direct relaxation entrains a broadening of the spectra and is capable of qualitatively capturing the main features in the experimental spectra and quantitatively capturing the characteristic time scale of the vibrational dynamics of the Cl - H → stretching band. Furthermore, due to the decent agreement obtained between the theoretical and experimental line shapes at 226 K, the evolution of the IR spectra with the varaiation of temperature is proposed. The findings gained herein underscore the utility of combining simultaneously the effects of

  15. Coherent infrared multidimensional spectra of the OH stretching band in liquid water simulated by direct nonlinear exciton propagation

    Science.gov (United States)

    Falvo, Cyril; Palmieri, Benoit; Mukamel, Shaul

    2009-05-01

    The two-dimensional vibrational response of the disordered strongly fluctuating OH exciton band in liquid water is investigated using a new simulation protocol. The direct nonlinear exciton propagation generalizes the nonlinear exciton equations to include nonadiabatic time dependent Hamiltonian and transition dipole fluctuations. The excitonic picture is retained and the large cancellation between Liouville pathways is built-in from the outset. The sensitivity of the photon echo and double-quantum-coherence techniques to frequency fluctuations, molecular reorientation, intermolecular coupling, and the two-exciton coherence is investigated. The photon echo is particularly sensitive to the frequency fluctuations and molecular reorientation, whereas the double-quantum coherence provides a unique probe for intermolecular couplings and two-exciton coherence.

  16. Effect of Post-Exercise Whole Body Vibration with Stretching on Mood State, Fatigue, and Soreness in Collegiate Swimmers

    Directory of Open Access Journals (Sweden)

    Justin J. Merrigan

    2017-01-01

    Full Text Available Static stretching (SS during whole body vibration (WBV has been suggested for exercise recovery. The purpose was to compare post-exercise self-ratings of fatigue (FAT, mood state (BAM, soreness (SOR, and perceived exertion (RPE between SS and WBV+SS in swimmers (9 women, mean ± SD: 19.3 ± 1.3 year, 171 ± 5.7 cm, 67.6 ± 7.2 kg, 26.6 ± 4.1 %body fat (%BF; 10 men, mean ± SD: 19.7 ± 1.0 year, 183 ± 5.5 cm, 77.1 ± 4.2 kg, 13.1 ± 2.2 %BF. Athletes were divided by sex, event (sprint, distance, and assigned to SS or WBV+SS. Both conditions consisted of SS performed on the WBV platform with or without WBV (50 Hz, 6 mm. Sessions consisted of: pre and post measures of BAM, FAT, SOR; the condition; and RPE. Mixed factorial ANOVA were run. A significant condition by pre/post interaction was observed (p = 0.035. Post hoc analyses showed WBV+SS elicited lower post-exercise ratings of FAT (p = 0.002 and the BAM affective states, of tension (p = 0.031, and fatigue (p = 0.087. RPE did not differ between conditions. Of interest is the decrease in tension and fatigue noted by the BAM. Mood state can be indicative of how athletes adapt to training volume and intensity.

  17. Collisional and infrared radiative pumping of molecular vibrational states - The carbon monoxide infrared bands

    Science.gov (United States)

    Scoville, N. Z.; Krotkov, R.; Wang, D.

    1980-09-01

    An analysis of the nonlocal thermodynamic equilibrium resulting from collisions, direct pumping of infrared radiation, and UV fluorescence was made to identify the observational 'signatures' and estimate the efficiency of each process in production of vibrational line protons. The relative populations of the vibrational levels are characterized by a single excitation temperature for all modes of excitation; this is shown by the solution of the full rate equations governing the statistical equilibrium of the CO level populations. The high emissivities estimated for the CO IR band indicate that CO will dominate over H2 in the cooling of high-temperature molecular gas at densities above 10 to the 7th/cu cm; such conditions occur in a shock-heated gas in the cores of molecular clouds or in protostellar nebulae.

  18. Direct interaction of fast neutrons with β and γ vibrational band levels of tungsten even isotopes

    International Nuclear Information System (INIS)

    Delaroche, J.P.

    1982-09-01

    As an extension of a previous report on fast neutron scattering from the first and second excited states of 182 W, 184 W, 186 W, we have investigated the question of the importance of direct interaction of neutrons with β- and γ-band levels of these nuclei. For that purpose we have performed new coupled channel calculations using extended coupling bases and collective functions from the Rotation-Vibration and Kumar and Baranger Models. The predictions are compared with recent scattering data obtained at incident energies below 4 MeV [fr

  19. Isotropic collision-induced scattering by CF4 in a Raman vibrational band

    Science.gov (United States)

    Godet, J.-L.; Elliasmine, A.; Le Duff, Y.; Bancewicz, T.

    1999-06-01

    Light-scattering intensities and depolarization ratio data have been recorded at room temperature for gaseous tetrafluoromethane in the collision-induced band of the Raman vibrational line ν1=908 cm-1. For the first time, binary isotropic intensities of the ν1-Raman band are reported in absolute units for Stokes frequency shifts up to 110 cm-1. From comparison with theoretical semiclassical computations of the dipole-multipole spectrum contributions, evaluations of the first derivatives of the successive dipole-multipole polarizability tensors are provided. These results are coherent with those obtained from corresponding depolarized intensities. Moreover, the agreement with ab initio quantum-chemistry calculations of the CF4 multipolar polarizabilities is satisfactory.

  20. Vibrational dynamics and band structure of methyl-terminated Ge(111)

    International Nuclear Information System (INIS)

    th Street, Chicago, Illinois 60637 (United States))" data-affiliation=" (The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 (United States))" >Hund, Zachary M.; th Street, Chicago, Illinois 60637 (United States))" data-affiliation=" (The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 (United States))" >Nihill, Kevin J.; th Street, Chicago, Illinois 60637 (United States))" data-affiliation=" (The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 (United States))" >Sibener, S. J.; Campi, Davide; Bernasconi, M.; Wong, Keith T.; Lewis, Nathan S.; Benedek, G.

    2015-01-01

    A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD 3 -Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH 3 -Ge(111) and CH 3 -Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers

  1. Vibrational dynamics and band structure of methyl-terminated Ge(111)

    Energy Technology Data Exchange (ETDEWEB)

    Hund, Zachary M.; Nihill, Kevin J.; Sibener, S. J., E-mail: s-sibener@uchicago.edu [The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57" t" h Street, Chicago, Illinois 60637 (United States); Campi, Davide; Bernasconi, M. [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Wong, Keith T.; Lewis, Nathan S. [Division of Chemistry and Chemical Engineering, Beckman Institute and Kavli Nanoscience Institute, California Institute of Technology, 210 Noyes Laboratory, 127-72, Pasadena, California 91125 (United States); Benedek, G. [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Donostia International Physics Center (DIPC), Universidad del País Vasco (EHU), 20018 Donostia/San Sebastian (Spain)

    2015-09-28

    A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD{sub 3}-Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH{sub 3}-Ge(111) and CH{sub 3}-Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers.

  2. Effects of intermolecular interactions on absorption intensities of the fundamental and the first, second, and third overtones of OH stretching vibrations of methanol and t-butanol‑d9in n-hexane studied by visible/near-infrared/infrared spectroscopy.

    Science.gov (United States)

    Morisawa, Yusuke; Suga, Arisa

    2018-05-15

    Visible (Vis), near-infrared (NIR) and IR spectra in the 15,600-2500cm -1 region were measured for methanol, methanol-d 3 , and t-butanol-d 9 in n-hexane to investigate effects of intermolecular interaction on absorption intensities of the fundamental and the first, second, and third overtones of their OH stretching vibrations. The relative area intensities of OH stretching bands of free and hydrogen-bonded species were plotted versus the vibrational quantum number using logarithm plots (V=1-4) for 0.5M methanol, 0.5M methanol‑d 3 , and 0.5M t-butanol-d 9 in n-hexane. In the logarithm plots the relative intensities of free species yield a linear dependence irrespective of the solutes while those of hydrogen-bonded species deviate significantly from the linearity. The observed results suggest that the modifications in dipole moment functions of the OH bond induced by the formation of the hydrogen bondings change transient dipole moment, leading to the deviations of the dependences of relative absorption intensities on the vibrational quantum number from the linearity. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Concentric and eccentric time-under-tension during strengthening exercises: validity and reliability of stretch-sensor recordings from an elastic exercise-band.

    Directory of Open Access Journals (Sweden)

    Michael Skovdal Rathleff

    Full Text Available BACKGROUND: Total, single repetition and contraction-phase specific (concentric and eccentric time-under-tension (TUT are important exercise-descriptors, as they are linked to the physiological and clinical response in exercise and rehabilitation. OBJECTIVE: To investigate the validity and reliability of total, single repetition, and contraction-phase specific TUT during shoulder abduction exercises, based on data from a stretch-sensor attached to an elastic exercise band. METHODS: A concurrent validity and interrater reliability study with two raters was conducted. Twelve participants performed five sets of 10 repetitions of shoulder abduction exercises with an elastic exercise band. Exercises were video-recorded to assess concurrent validity between TUT from stretch-sensor data and from video recordings (gold standard. Agreement between methods was calculated using Limits of Agreement (LoA, and the association was assessed by Pearson correlation coefficients. Interrater reliability was calculated using intraclass correlation coefficients (ICC 2.1. RESULTS: Total, single repetition, and contraction-phase specific TUT - determined from video and stretch-sensor data - were highly correlated (r>0.99. Agreement between methods was high, as LoA ranged from 0.0 to 3.1 seconds for total TUT (2.6% of mean TUT, from -0.26 to 0.56 seconds for single repetition TUT (6.9%, and from -0.29 to 0.56 seconds for contraction-phase specific TUT (13.2-21.1%. Interrater reliability for total, single repetition and contraction-phase specific TUT was high (ICC>0.99. Interrater agreement was high, as LoA ranged from -2.11 to 2.56 seconds for total TUT (4.7%, from -0.46 to 0.50 seconds for single repetition TUT (9.7% and from -0.41 to 0.44 seconds for contraction-phase specific TUT (5.2-14.5%. CONCLUSION: Data from a stretch-sensor attached to an elastic exercise band is a valid measure of total and single repetition time-under-tension, and the procedure is highly

  4. Vibrational and electronic spectroscopic studies of melatonin

    Science.gov (United States)

    Singh, Gurpreet; Abbas, J. M.; Dogra, Sukh Dev; Sachdeva, Ritika; Rai, Bimal; Tripathi, S. K.; Prakash, Satya; Sathe, Vasant; Saini, G. S. S.

    2014-01-01

    We report the infrared absorption and Raman spectra of melatonin recorded with 488 and 632.8 nm excitations in 3600-2700 and 1700-70 cm-1 regions. Further, we optimized molecular structure of the three conformers of melatonin within density functional theory calculations. Vibrational frequencies of all three conformers have also been calculated. Observed vibrational bands have been assigned to different vibrational motions of the molecules on the basis of potential energy distribution calculations and calculated vibrational frequencies. Observed band positions match well with the calculated values after scaling except Nsbnd H stretching mode frequencies. It is found that the observed and calculated frequencies mismatch of Nsbnd H stretching is due to intermolecular interactions between melatonin molecules.

  5. Lock threshold deterioration induced by antenna vibration and signal coupling effects in hypersonic vehicle carrier tracking system of Ka band

    Directory of Open Access Journals (Sweden)

    Congying ZHU

    2018-04-01

    Full Text Available The envelope of a hypersonic vehicle is affected by severe fluctuating pressure, which causes the airborne antenna to vibrate slightly. This vibration mixes with the transmitted signals and thus introduces additional multiplicative phase noise. Antenna vibration and signal coupling effects as well as their influence on the lock threshold of the hypersonic vehicle carrier tracking system of the Ka band are investigated in this study. A vibration model is initially established to obtain phase noise in consideration of the inherent relationship between vibration displacement and electromagnetic wavelength. An analytical model of the Phase-Locked Loop (PLL, which is widely used in carrier tracking systems, is established. The coupling effects on carrier tracking performance are investigated and quantitatively analyzed by imposing the multiplicative phase noise on the PLL model. Simulation results show that the phase noise presents a Gaussian distribution and is similar to vibration displacement variation. A large standard deviation in vibration displacement exerts a significant effect on the lock threshold. A critical standard deviation is observed in the PLL of Binary Phase Shift Keying (BPSK and Quadrature Phase Shift Keying (QPSK signals. The effect on QPSK signals is more severe than that on BPSK signals. The maximum tolerable standard deviations normalized by the wavelength of the carrier are 0.04 and 0.02 for BPSK and QPSK signals, respectively. With these critical standard deviations, lock thresholds are increased from −12 and −4 dB to 3 and −2 dB, respectively. Keywords: Antenna vibration, Carrier tracking performance, Lock threshold, Phase locked loop, Tracking Telemetry and Command (TT&C signals

  6. Effects of Rippling Deformation and Mid-Plane Stretching on Non-linear Vibration for Embedded Carbon Nanotube

    DEFF Research Database (Denmark)

    Mehdipour, I.; Barari, Amin; Domairry, G.

    2012-01-01

    natural frequencies or mode shapes if a sufficiently precise theoretical model is used. The molecular dynamics (MD) method simulates CNTs accurately. However, MD simulation is limited to systems with a small number of atoms (say, less than 1016) and remains time-consuming and expensive (Yaghmaei and Rafii......-Tabar, 2009; Zhang et al., 2009; Gibson et al., 2007). For large-scale systems, continuum mechanics approach has widely and successfully modeled mechanical and vibrational characteristics of CNTs (Gibson et al., 2007; Fu et al., 2006; Ranjbartoreh et al., 2007). The continuum modeling approach needs much less...

  7. Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

    Science.gov (United States)

    Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

    2006-04-20

    Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

  8. Flow induced vibrations of the CLIC X-Band accelerating structures

    CERN Document Server

    Charles, Tessa; Boland, Mark; Riddone, Germana; Samoshkin, Alexandre

    2011-01-01

    Turbulent cooling water in the Compact Linear Collider (CLIC) accelerating structures will inevitably induce some vibrations. The maximum acceptable amplitude of vibrations is small, as vibrations in the accelerating structure could lead to beam jitter and alignment difficulties. A Finite Element Analysis model is needed to identify the conditions under which turbulent instabilities and significant vibrations are induced. Due to the orders of magnitude difference between the fluid motion and the structure’s motion, small vibrations of the structure will not contribute to the turbulence of the cooling fluid. Therefore the resonant conditions of the cooling channels presented in this paper, directly identify the natural frequencies of the accelerating structures to be avoided under normal operating conditions. In this paper a 2D model of the cooling channel is presented finding spots of turbulence being formed from a shear layer instability. This effect is observed through direct visualization and wavelet ana...

  9. Heterogeneous Dynamics of Coupled Vibrations

    NARCIS (Netherlands)

    Cringus, Dan; Jansen, Thomas I. C.; Pshenichnikov, Maxim S.; Schoenlein, RW; Corkum, P; DeSilvestri, S; Nelson, KA; Riedle, E

    2009-01-01

    Frequency-dependent dynamics of coupled stretch vibrations of a water molecule are revealed by 2D IR correlation spectroscopy. These are caused by non-Gaussian fluctuations of the environment around the individual OH stretch vibrations.

  10. Effect of combining passive muscle stretching and whole body vibration on spasticity and physical performance of children and adolescents with cerebral palsy.

    Science.gov (United States)

    Tupimai, Teeraporn; Peungsuwan, Punnee; Prasertnoo, Jitlada; Yamauchi, Juinichiro

    2016-01-01

    [Purpose] This study evaluated the immediate and short-term effects of a combination of prolonged passive muscle stretching (PMS) and whole body vibration (WBV) on the spasticity, strength and balance of children and adolescents with cerebral palsy. [Subjects and Methods] A randomized two-period crossover trial was designed. Twelve subjects with cerebral palsy aged 10.6 ± 2.4 years received both PMS alone as a control group (CG) and a combination of PMS and WBV as an experimental group (EG). After random allocation to the trial schedules of either EG-CG or CG-EG, CG received prolonged PMS while standing on a tilt-table for 40 minutes/day, and EG received prolonged PMS for 30 minutes, followed by 10 minutes WBV. Both CG and EG received the treatment 5 days/week for 6 weeks. [Results] Immediately after one treatment, EG resulted in better improvement in scores on the Modified Ashworth Scale than CG. After the 6-week intervention, EG also showed significantly decreased scores on the Modified Ashworth Scale compared to CG. Both CG and EG showed significantly reduced the performance times in the five times sit to stand test, and EG also showed significantly increased scores on the pediatric balance scale. [Conclusion] This study showed that 6 weeks of combined prolonged PMS and WBV had beneficial effects on the spasticity, muscle strength and balance of children and adolescents with CP.

  11. Spectra and relaxation dynamics of the pseudohalide (PS) vibrational bands for Ru(bpy){sub 2}(PS){sub 2} complexes, PS = CN, NCS and N{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Compton, Ryan; Gerardi, Helen K. [Chemistry Division, Naval Research Laboratory, Washington, DC 20375 (United States); Weidinger, Daniel [SRA International, 4300 Fair Lakes Court, Fairfax, VA 22033 (United States); Brown, Douglas J. [Chemistry Department, US Naval Academy, Annapolis, MD 21402 (United States); Dressick, Walter J. [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC 20375 (United States); Heilweil, Edwin J. [Radiation and Biomolecular Physics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Owrutsky, Jeffrey C., E-mail: Jeff.Owrutsky@nrl.navy.mil [Chemistry Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2013-08-30

    Highlights: ► Static and transient infrared spectroscopy of pseudohalide bipyridine ruthenium complexes. ► Vibrational energy relaxes faster for the azide than the thiocyanate and cyanide analogs. ► Intramolecular vibrational relaxation is prevalent in cis-Ru(bpy){sub 2}(N{sub 3}){sub 2}. - Abstract: Static and transient infrared spectroscopy were used to investigate cis-Ru(bpy){sub 2}(N{sub 3}){sub 2} (bpy = 2,2′-bipyridine), cis-Ru(bpy){sub 2}(NCS){sub 2}, and cis-Ru(bpy){sub 2}(CN){sub 2} in solution. The NC stretching IR band for cis-Ru(bpy){sub 2}(NCS){sub 2} appears at higher frequency (∼2106 cm{sup −1} in DMSO) than for the free NCS{sup −} anion while the IR bands for the azide and cyanide complexes are closer to those of the respective free anions. The vibrational energy relaxation (VER) lifetime for the azide complex is found to be much shorter (∼5 ps) than for either the NCS or CN species (both ∼70 ps in DMSO) and the lifetimes resemble those for each corresponding free anion in solution. However, for cis-Ru(bpy){sub 2}(N{sub 3}){sub 2}, it is determined that the transition frequency depends more on the solvent than the VER lifetime implying that intramolecular vibrational relaxation is predominant over solvent energy-extracting interactions. These results are compared to the behavior of other related metal complexes in solution.

  12. A combined Raman spectroscopic and theoretical investigation of fundamental vibrational bands of furfuryl alcohol (2-furanmethanol)

    DEFF Research Database (Denmark)

    Barsberg, S.; Berg, Rolf W.

    2006-01-01

    conformational states, each with >5% probability, and two of these dominate at T = 298 K. Excluding one frequency, the remaining ones are predicted as a weighted av. over the two dominant conformers to a best root-mean-square error of 8 cm-1 and are qual. assigned. The excluded CH stretching mode...

  13. Systematics of the K 2·gamma vibrational bands and odd–even ...

    Indian Academy of Sciences (India)

    even staggering in the γ-band to the contribution of the Coriolis interaction besides the band interaction effects. Liao-Ji Zhi [8] illustrated the variation of the OES with angular momentum J of some well-deformed nuclei. Bonatsos illustrated the shift of odd-spin members from the even-spin ones in the γ-bands of Gd, Dy, ...

  14. Alleviation of Motor Impairments in Patients with Cerebral Palsy: Acute Effects of Whole-body Vibration on Stretch Reflex Response, Voluntary Muscle Activation and Mobility

    Directory of Open Access Journals (Sweden)

    Anne Krause

    2017-08-01

    Full Text Available IntroductionIndividuals suffering from cerebral palsy (CP often have involuntary, reflex-evoked muscle activity resulting in spastic hyperreflexia. Whole-body vibration (WBV has been demonstrated to reduce reflex activity in healthy subjects, but evidence in CP patients is still limited. Therefore, this study aimed to establish the acute neuromuscular and kinematic effects of WBV in subjects with spastic CP.Methods44 children with spastic CP were tested on neuromuscular activation and kinematics before and immediately after a 1-min bout of WBV (16–25 Hz, 1.5–3 mm. Assessment included (1 recordings of stretch reflex (SR activity of the triceps surae, (2 electromyography (EMG measurements of maximal voluntary muscle activation of lower limb muscles, and (3 neuromuscular activation during active range of motion (aROM. We recorded EMG of m. soleus (SOL, m. gastrocnemius medialis (GM, m. tibialis anterior, m. vastus medialis, m. rectus femoris, and m. biceps femoris. Angular excursion was recorded by goniometry of the ankle and knee joint.ResultsAfter WBV, (1 SOL SRs were decreased (p < 0.01 while (2 maximal voluntary activation (p < 0.05 and (3 angular excursion in the knee joint (p < 0.01 were significantly increased. No changes could be observed for GM SR amplitudes or ankle joint excursion. Neuromuscular coordination expressed by greater agonist–antagonist ratios during aROM was significantly enhanced (p < 0.05.DiscussionThe findings point toward acute neuromuscular and kinematic effects following one bout of WBV. Protocols demonstrate that pathological reflex responses are reduced (spinal level, while the execution of voluntary movement (supraspinal level is improved in regards to kinematic and neuromuscular control. This facilitation of muscle and joint control is probably due to a reduction of spasticity-associated spinal excitability in favor of giving access for greater supraspinal input during voluntary motor

  15. Vibrational spectra of opal-based photonic crystals

    International Nuclear Information System (INIS)

    Dovbeshko, G; Fesenko, O; Boyko, V; Romanyuk, V; Moiseyenko, V; Gorelik, V; Dolgov, L; Kiisk, V; Sildos, I

    2012-01-01

    Synthetic silica opals were investigated by infrared and Raman spectroscopies. Vibrational modes associated with molecular groups of opal globules and admixtures were detected. Similarities in Raman and infrared spectra of synthetic opal with reference fused and α-quartz indicate the presence of amorphous phase in opal globules. Also some spectral bands designate on modified optical stretching vibrations at 1000-1200 cm −1 and bigger amount of Si-H defects in photonic crystal.

  16. The amide III vibrational circular dichroism band as a probe to detect conformational preferences of alanine dipeptide in water.

    Science.gov (United States)

    Mirtič, Andreja; Merzel, Franci; Grdadolnik, Jože

    2014-07-01

    The conformational preferences of blocked alanine dipeptide (ADP), Ac-Ala-NHMe, in aqueous solution were studied using vibrational circular dichroism (VCD) together with density functional theory (DFT) calculations. DFT calculations of three most representative conformations of ADP surrounded by six explicit water molecules immersed in a dielectric continuum have proven high sensitivity of amide III VCD band shape that is characteristic for each conformation of the peptide backbone. The polyproline II (PII ) and αR conformation of ADP are associated with a positive VCD band while β conformation has a negative VCD band in amide III region. Knowing this spectral characteristic of each conformation allows us to assign the experimental amide III VCD spectrum of ADP. Moreover, the amide III region of the VCD spectrum was used to determine the relative populations of conformations of ADP in water. Based on the interpretation of the amide III region of VCD spectrum we have shown that dominant conformation of ADP in water is PII which is stabilized by hydrogen bonded water molecules between CO and NH groups on the peptide backbone. Copyright © 2014 Wiley Periodicals, Inc.

  17. Twenty-Eight Orders of Parametric Resonance in a Microelectromechanical Device for Multi-band Vibration Energy Harvesting

    Science.gov (United States)

    Jia, Yu; Du, Sijun; Seshia, Ashwin A.

    2016-01-01

    This paper contends to be the first to report the experimental observation of up to 28 orders of parametric resonance, which has thus far only been envisioned in the theoretical realm. While theory has long predicted the onset of n orders of parametric resonance, previously reported experimental observations have been limited up to about the first 5 orders. This is due to the rapid narrowing nature of the frequency bandwidth of the higher instability intervals, making practical accessibility increasingly more difficult. Here, the authors have experimentally confirmed up to 28 orders of parametric resonance in a micromachined membrane resonator when electrically undamped. While the implication of this finding spans across the vibration dynamics and transducer application spectrum, the particular significance of this work is to broaden the accumulative operational frequency bandwidth of vibration energy harvesting for enabling self-powered microsystems. Up to 5 orders were recorded when driven at 1.0 g of acceleration across a matched load of 70 kΩ. With a natural frequency of 980 Hz, the fundamental mode direct resonance had a −3 dB bandwidth of 55 Hz, in contrast to the 314 Hz for the first order parametric resonance; furthermore, the half power bands of all 5 orders accumulated to 478 Hz. PMID:27445205

  18. Infrared spectroscopy and Density Functional Theory of crystalline β-2,4,6,8,10,12-hexanitrohexaaziosowurtzitane (β CL-20) in the region of its C-H stretching vibrations.

    Science.gov (United States)

    Behler, K D; Pesce-Rodriguez, R; Cabalo, J; Sausa, R

    2013-10-01

    Molecular vibrational spectroscopy provides a useful tool for material characterization and model verification. We examine the CH stretching fundamental and overtones of energetic material β-2,4,6,8,10,12-hexanitrohexaaziosowurtzitane (β-CL-20) by Raman spectroscopy, Fourier Transform Infrared Spectroscopy, and Laser Photoacoustic Overtone Spectroscopy, and utilize Density Functional Theory to calculate the C-H bond energy of β-CL-20 in a crystal. The spectra reveal four intense and distinct features, whose analysis yields C-H stretching fundamental frequencies and anharmonicity values that range from 3137 to 3170 cm(-1) and 53.8 to 58.8 cm(-1), respectively. From these data, we estimate an average value of 42,700 cm(-1) (5.29 eV) for the C-H bond energy, a value that agrees with our quantum mechanical calculations. Published by Elsevier B.V.

  19. Characterization and Simulation of Transient Vibrations Using Band Limited Temporal Moments

    Directory of Open Access Journals (Sweden)

    David O. Smallwood

    1994-01-01

    Full Text Available A method is described to characterize shocks (transient time histories in terms of the Fourier energy spectrum and the temporal moments of the shock passed through a contiguous set of band pass filters. The product model is then used to generate of a random process as simulations that in the mean will have the same energy and moments as the characterization of the transient event.

  20. Secondary structure estimation and properties analysis of stretched Asian and Caucasian hair.

    Science.gov (United States)

    Zhou, A J; Liu, H L; Du, Z Q

    2015-02-01

    In this previous work, we investigated the secondary structure changes of stretched yak hairs by deconvolution, secondary derivation, and curve fitting and determined the number of bands and their positions in order to resolve the protein spectrum of Raman spectroscopy. The secondary structure estimation and properties analysis of stretched Asian and Caucasian hair were investigated by Fourier transform infrared spectroscopy, tensile curves, and measurement of density. The hairs were stretched, dried, and baked at ratios 20%, 40%, 60%, 80% and 100%. The analysis of the amide I band indicated that the transformation from α-helix to β-pleated structure occurred during the stretching process, which could be verified from the tensile analysis. The cysteine oxide in S-O vibration area exhibited that stretching led to the breakage of the disulfide bonds. When the stretching ratio of Caucasian hair was more than a certain ratio, the fiber macromolecular structure was destroyed because Caucasian hair had finer diameter and less medulla than Asian hair. The β turn was easier to retract compared with other conformations, resulted in the content increase. The density measurements revealed that the structure of Caucasian hair was indeed more destroyed than that of Asian hair. The cuticles characterization indicated the length of scales was stretched longer and the thickness became thinner. Caucasian hair tended to collapse to form small fragments at the early stage of stretching. With the increase in stretching ratio, the scales of Caucasian hair lifted up, then flaked off and the scale interval increased accordingly. Asian hair was more easily peeled off than Caucasian hair cuticles with the increase in stretching ratio. The secondary structure of Caucasian hair was destroyed more easily than that of Asian hair. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Sub-Doppler Resolution Spectroscopy of the Fundamental Vibration Band of HCl with a Comb-Referenced Spectrometer

    Science.gov (United States)

    Iwakuni, Kana; Sera, Hideyuki; Abe, Masashi; Sasada, Hiroyuki

    2015-06-01

    Sub-Doppler resolution spectroscopy of the fundamental bands of H35Cl and H37Cl has been carried out from 87 to 90 THz using a comb-referenced difference-frequency-generation (DFG) spectrometer. While the frequencies of the pump and signal waves are locked to that of the individual nearest comb mode, the repetition rate of the comb is varied for sweeping the idler frequency. Therefore, the relative uncertainty of the frequency scale is 10-11, and the spectral resolution remains about 250 kHz even when the spectrum is accumulated for a long time. The hyperfine structures caused by chlorine nucleus are resolved for the R(0) to R(4) transitions. The figure depicts wavelength-modulation spectrum of the R(0) transition of H35Cl. Three Lamb dips correspond to the F= 0, 1, and -1 components left to right, and the others with arrows are cross-over resonances which are useful for determining the weak F=-1 component frequencies for the R(1) to R(3) transitions. We have determined 49 and 44 transition frequencies of H35Cl and H37Cl with an uncertainty of 10 kHz. Six molecular constants of the vibrational excited state for each isotopomer are determined. They reproduce the determined frequencies with a standard deviation of about 10 kHz.

  2. Calculation and fitting of potential energy and dipole moment surfaces for the water molecule: Fully ab initio determination of vibrational transition energies and band intensities

    International Nuclear Information System (INIS)

    Kedziora, G.S.; Shavitt, I.

    1997-01-01

    Potential energy and dipole moment surfaces for the water molecule have been generated by multireference singles-and-doubles configuration interaction calculations using a large basis set of the averaged-atomic-natural-orbital type and a six-orbital-six-electron complete-active-space reference space. The surfaces are suitable for modeling vibrational transitions up to about 11000cm -1 above the ground state. A truncated singular-value decomposition method has been used to fit the surfaces. This fitting method is numerically stable and is a useful tool for examining the effectiveness of various fitting function forms in reproducing the calculated surface points and in extrapolating beyond these points. The fitted surfaces have been used for variational calculations of the 30 lowest band origins and the corresponding band intensities for transitions from the ground vibrational state. With a few exceptions, the results compare well with other calculations and with experimental data. copyright 1997 American Institute of Physics

  3. Torsion - Vibration Couplings in the CH{_3}OO{\\cdot} Radical

    Science.gov (United States)

    Huang, Meng; Miller, Terry A.; McCoy, Anne B.; Hsu, Kuo-Hsiang; Huang, Yu-Hsuan; Lee, Yuan-Pern

    2016-06-01

    A partially rotationally resolved infrared spectrum of CH{_3}OO{\\cdot} in the CH stretch region has been reported. The rotational contour of the {ν_2} CH stretch band in the experimental spectrum can be simulated with an asymmetric rotor model. The simulation shows good agreement with the experimental spectrum except that the broadening of the Q-branch in the experimental spectrum remains unexplained. This broadening is likely due to the sequence band transitions from the torsionally excited levels populated at room temperature to combination levels involving the CH stretch and the same number of torsional quanta. A four dimension model involving three CH stretches and the CH{_3} torsion is applied to the CH{_3}OO{\\cdot} radical to obtain the frequencies and intensities of the vibrational transitions in the CH stretch region. Based on these calculations, the torsional sequence bands are calculated to be slightly shifted from the origin band, because of the couplings between the CH stretches and CH{_3} torsion, thereby causing the apparent broadening observed for the {ν_2} fundamental. Due to the accidental degeneracy of two different CH stretch and CH{_3} torsion combination levels which differ by one quantum in the torsional excitation, the frequencies of the torsional sequence bands will be very sensitive to details of the potential, which makes the shifts difficult to precisely predict with electronic structure calculations. Complementary analyses are now underway for the other two CH stretch vibrational bands, {ν_1} and {ν_9}. K.-H. Hsu, Y.-H. Huang, Y.-P. Lee, M. Huang, T. A. Miller and A. B. McCoy J. Phys. Chem. A, in press, DOI: 10.1021/acs.jpca.5b12334

  4. Theoretical Study of Vibrationally Averaged Dipole Moments for the Ground and Excited C=O Stretching States of trans-Formic Acid

    Czech Academy of Sciences Publication Activity Database

    Paulson, L. O.; Kaminský, Jakub; Anderson, D. T.; Bouř, Petr; Kubelka, J.

    2010-01-01

    Roč. 6, č. 3 (2010), s. 817-827 ISSN 1549-9618 R&D Projects: GA ČR GA202/07/0732; GA AV ČR IAA400550702 Grant - others:CAREER(US) 0846140; AV ČR(CZ) M200550902 Institutional research plan: CEZ:AV0Z40550506 Keywords : dipole moments * theoretical modelling * vibrational averaging Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.138, year: 2010

  5. Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy

    Science.gov (United States)

    Galván, Ismael; Jorge, Alberto; Solano, Francisco; Wakamatsu, Kazumasa

    2013-06-01

    We characterize for the first time the vibrational state of natural pheomelanin using Raman spectroscopy and model pigment synthesized from 5-S-cysteinyldopa. The shape of the Raman spectrum was very different from that of eumelanin. Four Raman bands were visible in the 500-2000 cm-1 wavenumber region about 500, 1150, 1490 and 2000 cm-1, which we assigned to the out-of-plane deformation and the stretching vibration of the phenyl rings, to the stretching vibration of C-N bonds or the stretching and wagging vibration of CH2, and to overtone or combination bands. Interestingly, we also show that the Raman spectrum of synthetic trichochrome F, a pigment that may be produced along with pheomelanin during pheomelanogenesis, is different from that of pheomelanin and similar to the spectrum of eumelanin. We could detect Raman signal of both eumelanin and pheomelanin in feathers and hairs where both pigments simultaneously occur without the need of isolating the pigment. This indicates that Raman spectroscopy represents a non-invasive method to detect pheomelanin and distinguish it from other pigments. This may be especially relevant to detect pheomelanin in animal skin including humans, where it has been associated with animal appearance and classification, human phototypes, prevention of skin diseases and cancer risk.

  6. Frequency-comb-assisted absolute calibration and linestrength of H12C13CH ro-vibrational transitions in the 2ν3 band

    Science.gov (United States)

    Di Sarno, Valentina; De Natale, Paolo; Tasseva, Jordanka; Santamaria, Luigi; Cané, Elisabetta; Tamassia, Filippo; Maddaloni, Pasquale

    2018-02-01

    We report on a precision spectroscopic study of room-temperature H12C13CH in the 6463-6520 cm-1 range, using a continuous-wave diode laser phase-locked to a near-infrared optical frequency comb synthesizer stabilized, in turn, against a GPS-disciplined rubidium clock. By tuning the comb repetition frequency, several ro-vibrational transitions in the P and R branches of the 2ν3 overtone band are recorded. Accuracy levels as low as 100 kHz, 5 ·10-10 in fractional terms, are obtained in the determination of absolute line-center frequencies. In addition, line intensities are measured for the first time, with a best fractional uncertainty of 1%, and used to retrieve the purely vibrational transition dipole moment in conjunction with the first-order Herman-Wallis factor. Finally, the pressure broadening coefficients γself are also derived for the studied transitions.

  7. Study of Perfluoroalkyl Chain-Specific Band Shift in Infrared Spectra on the Chain Length.

    Science.gov (United States)

    Shimoaka, Takafumi; Sonoyama, Masashi; Amii, Hideki; Takagi, Toshiyuki; Kanamori, Toshiyuki; Hasegawa, Takeshi

    2017-11-09

    The CF 2 symmetric stretching vibration (ν s (CF 2 )) band of a perfluoroalkyl (Rf) group in an infrared (IR) spectrum exhibits a unique character, that is, an apparent high wavenumber shift with increasing the chain length, which is an opposite character to that of the CH stretching vibration band of a normal alkyl chain. To reveal the mechanism of the unusual IR band shift, two vibrational characters of an Rf chain are focused: (1) a helical conformation of an Rf chain, (2) the carbon (C) atoms having a smaller mass than the fluorine (F) atom dominantly vibrate as a coupled oscillator leaving F atoms stay relatively unmoved. These indicate that a "coupled oscillation of the skeletal C atoms" of an Rf chain should be investigated considering the helical structure. In the present study, therefore, the coupled oscillation of the Rf chain dependent on the chain length is investigated by Raman spectroscopy, which is suitable for investigating a skeletal vibration. The Raman-active ν s (CF 2 ) band is found to be split into two bands, the splitting is readily explained by considering the helical structure and length with respect to group theory, and the unusual peak shift is concluded to be explained by the helical length.

  8. Spectroscopy of C-H stretching overtones in dimethylacetylene, dimethylcadmium, and dimethylmercury

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares I., C.; Yamasaki, N.L.S.; Weitz, E. (Northwestern Univ., Evanston, IL (USA))

    1989-06-15

    The overtone spectra of a number of C-H stretching vibrations of dimethylacetylene, dimethylcadmium, and dimethylmercury were obtained by using intracavity dye laser photoacoustic spectroscopy. Transitions corresponding to the {Delta}{nu} = 5, 6, and 7 overtones of the C-H stretch are assigned by using the local-mode model. In addition, a number of local-mode-normal-mode combination bands have been identified. Local-mode harmonic frequencies ({omega}{sub e}) and anharmonicities ({omega}{sub e}x{sub e}) are obtained from Birge-Sponer plots. The line widths of the pure local-mode transitions are analyzed in terms of possible resonances with local-mode-normal-mode combination bands. Line widths in this series of compounds are compared to line widths in the M(CH{sub 3}){sub 4} and M(CH{sub 3}){sub 3} series.

  9. Developing a Stretching Program.

    Science.gov (United States)

    Beaulieu, J E

    1981-11-01

    In brief: Although stretching exercises can prevent muscle injuries and enhance athletic performance, they can also cause injury. The author explains the four most common types of stretching exercises and explains why he considers static stretching the safest. He also sets up a stretching routine for runners. In setting up a safe stretching program, one should (1) precede stretching exercises with a mild warm-up; (2) use static stretching; (3) stretch before and after a workout; (4) begin with mild and proceed to moderate exercises; (5) alternate exercises for muscle groups; (6) stretch gently and slowly until tightness, not pain, is felt; and (7) hold the position for 30 to 60 seconds.

  10. Stretch Sensor Device

    DEFF Research Database (Denmark)

    2013-01-01

    The invention relates to a method for determining stretch values and movement of body parts, e.g. a foot, by analysing stretch data from a stretch sensor. By analysing data from the stretch sensor it is possible to determine stretch samples which are associated with particular motion phases...

  11. A Computer Assisted Procedure of Assignments of Vibration-Rotation Bands of Asymmetric and Symmetric Top Molecules

    Czech Academy of Sciences Publication Activity Database

    Urban, Štěpán; Behrend, J.; Pracna, Petr

    2004-01-01

    Roč. 690, - (2004), s. 105-114 ISSN 0022-2860 R&D Projects: GA MŠk ME 445; GA ČR GA203/01/1274 Institutional research plan: CEZ:AV0Z4040901 Keywords : assigments of vibration-rotation spectra * combination differences * Loomis-Wood algorithm Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.200, year: 2004

  12. Application of comparative vibrational spectroscopic and mechanistic studies in analysis of fisetin structure

    Science.gov (United States)

    Dimitrić Marković, Jasmina M.; Marković, Zoran S.; Milenković, Dejan; Jeremić, Svetlana

    2011-12-01

    This paper addresses experimental and theoretical research in fisetin (2-(3,4-dihydroxyphenyl)-3,7-dihydroxychromen-4-one) structure by means of experimental IR and Raman spectroscopies and mechanistic calculations. Density Functional Theory calculations, with M05-2X functional and the 6-311+G (2df, p) basis set implemented in the Gaussian 09 package, are performed with the aim to support molecular structure, vibrational bands' positions and their intensities. Potential energy distribution (PED) values and the description of the largest vibrational contributions to the normal modes are calculated. The most intense bands appear in the 1650-1500 cm -1 wavenumber region. This region involves a combination of the C dbnd O, C2 dbnd C3 and C-C stretching vibrational modes. Most of the bands in the 1500-1000 cm -1 range involve C-C stretching, O-C stretching and in-plane C-C-H, C-O-H, C-C-O and C-C-C bending vibrations of the rings. The region below 1000 cm -1 is characteristic to the combination of in plane C-C-C-H, H-C-C-H, C-C-C-C, C-C-O-C and out of plane O-C-C-C, C-C-O-C, C-C-C-C torsional modes. The Raman spectra of baicalein and quercetin were used for qualitative comparison with fisetin spectrum and verification of band assignments. The applied detailed vibrational spectral analysis and the assignments of the bands, proposed on the basis of fundamentals, reproduced the experimental results with high degree of accuracy.

  13. Infrared laser spectroscopy of the n-propyl and i-propyl radicals: Stretch-bend Fermi coupling in the alkyl CH stretch region

    Science.gov (United States)

    Franke, Peter R.; Tabor, Daniel P.; Moradi, Christopher P.; Douberly, Gary E.; Agarwal, Jay; Schaefer, Henry F.; Sibert, Edwin L.

    2016-12-01

    The n-propyl and i-propyl radicals were generated in the gas phase via pyrolysis of n-butyl nitrite [CH3(CH2)3ONO] and i-butyl nitrite [(CH3)2CHCH2ONO], respectively. Nascent radicals were promptly solvated by a beam of He nanodroplets, and the infrared spectra of the radicals were recorded in the CH stretching region. Several previously unreported bands are observed between 2800 and 3150 cm-1. The CH stretching modes observed above 3000 cm-1 are in excellent agreement with CCSD(T) anharmonic frequencies computed using second-order vibrational perturbation theory. However, between 2800 and 3000 cm-1, the spectra of n- and i-propyl radicals become congested and difficult to assign due to the presence of multiple anharmonic resonance polyads. To model the spectrally congested region, Fermi and Darling-Dennison resonances are treated explicitly using "dressed" Hamiltonians and CCSD(T) quartic force fields in the normal mode representation, and the agreement with experiment is less than satisfactory. Computations employing local mode effective Hamiltonians reveal the origin of the spectral congestion to be strong coupling between the high frequency CH stretching modes and the lower frequency CHn bending/scissoring motions. The most significant coupling is between stretches and bends localized on the same CH2/CH3 group. Spectral simulations using the local mode approach are in excellent agreement with experiment.

  14. Dissimilar Dynamics of Coupled Water Vibrations

    NARCIS (Netherlands)

    Jansen, Thomas L. C.; Cringus, Dan; Pshenichnikov, Maxim S.

    2009-01-01

    Dissimilar dynamics of coupled stretch vibrations of a water molecule are revealed by two-dimensional, IR correlation spectroscopy. These are caused by essentially non-Gaussian fluctuations of the electric field exerted by the environment on the individual OH stretch vibrations. Non-Gaussian

  15. Experimental and numerical characterization of a mid-infrared plasmonic perfect absorber for dual-band enhanced vibrational spectroscopy

    Science.gov (United States)

    Aslan, Erdem; Aslan, Ekin; Turkmen, Mustafa; Saracoglu, Omer Galip

    2017-11-01

    Plasmonic perfect absorbers (PPAs) have promising properties to be utilized in molecular sensing and spectroscopy applications such as surface enhanced infrared absorption (SEIRA) and surface enhanced Raman spectroscopy (SERS). In order to employ these properties and demonstrate the great potential of PPAs, investigation and demonstration of PPA designs and their sensing applications are highly needed. In this context, we present the design, optical characterization, experimental realization and dual-band sensing application of a subwavelength PPA array for infrared detection and surface enhanced spectroscopy applications. We analyze the PPA to investigate the absorption spectra and the fine-tuning mechanism through the parameter sweep simulations and experiments. In order to understand the absorption mechanism, we investigate the charge and current density distribution maps with electric and magnetic field enhancement effects. Additionally, we demonstrate the potential usage and reliability of the proposed PPA by presenting the experimental results of the dual-band detection of a conformal polymethyl methacrylate layer with nanometer-scale thickness atop the PPA. According to the experimental and simulation results of this study, the proposed PPA can be utilized in multiband molecular detection and high sensitive spectroscopy applications.

  16. Sunlight-Initiated Photochemistry: Excited Vibrational States of Atmospheric Chromophores

    Directory of Open Access Journals (Sweden)

    Veronica Vaida

    2008-01-01

    Full Text Available Atmospheric chemical reactions are often initiated by ultraviolet (UV solar radiation since absorption in that wavelength range coincides to typical chemical bond energies. In this review, we present an alternative process by which chemical reactions occur with the excitation of vibrational levels in the ground electronic state by red solar photons. We focus on the O–H vibrational manifold which can be an atmospheric chromophore for driving vibrationally mediated overtone-induced chemical reactions. Experimental and theoretical O–H intensities of several carboxylic acids, alcohols, and peroxides are presented. The importance of combination bands in spectra at chemically relevant energies is examined in the context of atmospheric photochemistry. Candidate systems for overtone-initiated chemistry are provided, and their lowest energy barrier for reaction and the minimum quanta of O–H stretch required for reaction are calculated. We conclude with a discussion of the major pathways available for overtone-induced reactions in the atmosphere.

  17. CH PLIF and PIV implementation using C-X (0,0) and intra-vibrational band filtered detection

    Science.gov (United States)

    Hammack, Stephen D.; Skiba, Aaron W.; Lee, Tonghun; Carter, Campbell D.

    2018-02-01

    This study demonstrates advancement in a low-pulse energy methylidyne (CH) planar laser-induced fluorescence (PLIF) method that facilitates its application alongside flows seeded for particle image velocimetry (PIV) or other particle scattering based methods, as well as in high scattering environments. The C-X (0,0) R-branch excitation and filtered detection are carefully selected such that the laser line frequency is heavily attenuated by an edge filter while allowing transmission of most of the (0,0) band fluorescence. There are strong OH A-X (0,0) lines in the vicinity, but they can be avoided or utilized through dye laser tuning. As a demonstration of efficacy, PIV is performed simultaneously with the PLIF imaging. Using the edge filter, particle scattering signal is reduced to sub-fluorescence levels, allowing for flame-front analysis. This achievement enables flame-front tracking at high repetition rates (due to the low-pulse energy required) in combination with a scattering method such as PIV or use in high scattering environments such as enclosed combustors or near burner surfaces.

  18. Stretching Safely and Effectively

    Science.gov (United States)

    ... of stretching before or after hitting the trail, ballet floor or soccer field. Before you plunge into ... ballistic stretching on strength and muscular fatigue of ballet dancers and resistance-trained women. Journal of Strength ...

  19. Anharmonic bend-stretch coupling in neat liquid water

    NARCIS (Netherlands)

    Lindner, Joerg; Cringus, Dan; Pshenichnikov, Maxim S.; Voehringer, Peter

    2007-01-01

    Femtosecond mid-IR spectroscopy is used to study the vibrational relaxation dynamics in neat liquid water. By exciting the bending vibration and probing the stretching mode, it is possible to reliably determine the bending and librational lifetimes of water. The anharmonic coupling between the

  20. The vibrational spectrum of the hydrated alanine-leucine peptide in the amide region from IR experiments and first principles calculations

    Science.gov (United States)

    Hassan, Irtaza; Donati, Luca; Stensitzki, Till; Keller, Bettina G.; Heyne, Karsten; Imhof, Petra

    2018-04-01

    We have combined infrared (IR) experiments with molecular dynamics (MD) simulations in solution at finite temperature to analyse the vibrational signature of the small floppy peptide Alanine-Leucine. IR spectra computed from first-principles MD simulations exhibit no distinct differences between conformational clusters of α -helix or β -sheet-like folds with different orientations of the bulky leucine side chain. All computed spectra show two prominent bands, in good agreement with the experiment, that are assigned to the stretch vibrations of the carbonyl and carboxyl group, respectively. Variations in band widths and exact maxima are likely due to small fluctuations in the backbone torsion angles.

  1. B (E2) values of transitions from kπ= 0+→ 2+ vibrational bands in some well deformed heavy nuclei

    International Nuclear Information System (INIS)

    Singh, M.; Varshney, Mani; Gupta, D.K.; Bihari, Chhail; Singh, Yuvraj; Varshney, A.K.; Gupta, K.K

    2009-01-01

    There is simultaneous reduced B (E2) values of low-lying K π= 0 + → 2 + states, indicating a beta vibration like structure as well as the two particle transfer cross-section which suggest a pairing vibration like character and interpreted that low-lying k π= 0 + → 2 + resonance are classical beta vibrations. Recently, similar doubts about the origin of beta vibrations from surface oscillation have also been published

  2. Vibrational spectroscopic study of poldervaartite CaCa[SiO3(OH)(OH)

    Science.gov (United States)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo; Lima, Rosa Malena Fernandes

    2015-02-01

    We have studied the mineral poldervaartite CaCa[SiO3(OH)(OH)] which forms a series with its manganese analogue olmiite CaMn[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Thermogravimetric analysis proves the mineral decomposes at 485 °C with a mass loss of 7.6% compared with the theoretical mass loss of 7.7%. A strong Raman band at 852 cm-1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm-1 are attributed to the antisymmetric vibrations. Intense prominent peaks observed at 3487, 3502, 3509, 3521 and 3547 cm-1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of poldervaartite.

  3. Protonated Nitrous Oxide, NNOH(+): Fundamental Vibrational Frequencies and Spectroscopic Constants from Quartic Force Fields

    Science.gov (United States)

    Huang, Xinchuan; Fortenberry, Ryan C.; Lee, Timothy J.

    2013-01-01

    The interstellar presence of protonated nitrous oxide has been suspected for some time. Using established high-accuracy quantum chemical techniques, spectroscopic constants and fundamental vibrational frequencies are provided for the lower energy O-protonated isomer of this cation and its deuterated isotopologue. The vibrationally-averaged B0 and C0 rotational constants are within 6 MHz of their experimental values and the D(subJ) quartic distortion constants agree with experiment to within 3%. The known gas phase O-H stretch of NNOH(+) is 3330.91 cm(exp-1), and the vibrational configuration interaction computed result is 3330.9 cm(exp-1). Other spectroscopic constants are also provided, as are the rest of the fundamental vibrational frequencies for NNOH(+) and its deuterated isotopologue. This high-accuracy data should serve to better inform future observational or experimental studies of the rovibrational bands of protonated nitrous oxide in the ISM and the laboratory.

  4. Phosphate vibrations as reporters of DNA hydration

    Science.gov (United States)

    Corcelli, Steven

    The asymmetric phosphate stretch vibrational frequency is extraordinarily sensitive to its local solvent environment. Using density functional theory calculations on the model compound dimethyl phosphate, the asymmetric phosphate stretch vibrational frequency was found to shift linearly with the magnitude of an electric field along the symmetry axis of the PO2 moiety (i.e. the asymmetric phosphate stretch is an excellent linear vibrational Stark effect probe). With this linear relationship established, asymmetric phosphate stretch vibrational frequencies were computed during the course of a molecular dynamics simulation of fully hydrated DNA. Moreover, contributions to shifts in the frequencies from subpopulations of water molecules (e.g. backbone, minor groove, major groove, etc.) were calculated to reveal how phosphate vibrations report the onset of DNA hydration in experiments that vary the relative humidity of non-condensing (dry) DNA samples.

  5. Stretched Wire Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, Gordon; /SLAC

    2005-09-06

    Stretched wires are beginning to play an important role in the alignment of accelerators and synchrotron light sources. Stretched wires are proposed for the alignment of the 130 meter long LCLS undulator. Wire position technology has reached sub-micron resolution yet analyses of perturbations to wire straightness are hard to find. This paper considers possible deviations of stretched wire from the simple 2-dimensional catenary form.

  6. The immediate effect of vibration therapy on flexibility in female ...

    African Journals Online (AJOL)

    The immediate effect of vibration therapy on flexibility in female junior elite gymnasts. ... Therefore, the aim of this study was to investigate the acute effects of vibration therapy on the flexibility of female gymnasts. A pre-test ... Keywords: Static stretching, vibration training, vibration therapy, acute effect, artistic gymnastics.

  7. Instantaneous normal mode analysis for intermolecular and intramolecular vibrations of water from atomic point of view

    Science.gov (United States)

    Chen, Yu-Chun; Tang, Ping-Han; Wu, Ten-Ming

    2013-11-01

    By exploiting the instantaneous normal mode (INM) analysis for models of flexible molecules, we investigate intermolecular and intramolecular vibrations of water from the atomic point of view. With two flexible SPC/E models, our investigations include three aspects about their INM spectra, which are separated into the unstable, intermolecular, bending, and stretching bands. First, the O- and H-atom contributions in the four INM bands are calculated and their stable INM spectra are compared with the power spectra of the atomic velocity autocorrelation functions. The unstable and intermolecular bands of the flexible models are also compared with those of the SPC/E model of rigid molecules. Second, we formulate the inverse participation ratio (IPR) of the INMs, respectively, for the O- and H-atom and molecule. With the IPRs, the numbers of the three species participated in the INMs are estimated so that the localization characters of the INMs in each band are studied. Further, by the ratio of the IPR of the H atom to that of the O atom, we explore the number of involved OH bond per molecule participated in the INMs. Third, by classifying simulated molecules into subensembles according to the geometry of their local environments or their H-bond configurations, we examine the local-structure effects on the bending and stretching INM bands. All of our results are verified to be insensible to the definition of H-bond. Our conclusions about the intermolecular and intramolecular vibrations in water are given.

  8. Instantaneous normal mode analysis for intermolecular and intramolecular vibrations of water from atomic point of view.

    Science.gov (United States)

    Chen, Yu-Chun; Tang, Ping-Han; Wu, Ten-Ming

    2013-11-28

    By exploiting the instantaneous normal mode (INM) analysis for models of flexible molecules, we investigate intermolecular and intramolecular vibrations of water from the atomic point of view. With two flexible SPC/E models, our investigations include three aspects about their INM spectra, which are separated into the unstable, intermolecular, bending, and stretching bands. First, the O- and H-atom contributions in the four INM bands are calculated and their stable INM spectra are compared with the power spectra of the atomic velocity autocorrelation functions. The unstable and intermolecular bands of the flexible models are also compared with those of the SPC/E model of rigid molecules. Second, we formulate the inverse participation ratio (IPR) of the INMs, respectively, for the O- and H-atom and molecule. With the IPRs, the numbers of the three species participated in the INMs are estimated so that the localization characters of the INMs in each band are studied. Further, by the ratio of the IPR of the H atom to that of the O atom, we explore the number of involved OH bond per molecule participated in the INMs. Third, by classifying simulated molecules into subensembles according to the geometry of their local environments or their H-bond configurations, we examine the local-structure effects on the bending and stretching INM bands. All of our results are verified to be insensible to the definition of H-bond. Our conclusions about the intermolecular and intramolecular vibrations in water are given.

  9. Stretching: Does It Help?

    Science.gov (United States)

    Vardiman, Phillip; Carrand, David; Gallagher, Philip M.

    2010-01-01

    Stretching prior to activity is universally accepted as an important way to improve performance and help prevent injury. Likewise, limited flexibility has been shown to decrease functional ability and predispose a person to injuries. Although this is commonly accepted, appropriate stretching for children and adolescents involved with sports and…

  10. Thermal analysis and vibrational spectroscopic characterization of the boro silicate mineral datolite - CaBSiO4(OH)

    Science.gov (United States)

    Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; Lima, Rosa Malena Fernandes; Horta, Laura Frota Campos; Lopez, Andres

    2013-11-01

    The objective of this work is to determine the thermal stability and vibrational spectra of datolite CaBSiO4(OH) and relate these properties to the structure of the mineral. The thermal analysis of datolite shows a mass loss of 5.83% over a 700-775 °C temperature range. This mass loss corresponds to 1 water (H2O) molecules pfu. A quantitative chemical analysis using electron probe was undertaken. The Raman spectrum of datolite is characterized by bands at 917 and 1077 cm-1 assigned to the symmetric stretching modes of BO and SiO tetrahedra. A very intense Raman band is observed at 3498 cm-1 assigned to the stretching vibration of the OH units in the structure of datolite. BOH out-of-plane vibrations are characterized by the infrared band at 782 cm-1. The vibrational spectra are based upon the structure of datolite based on sheets of four- and eight-membered rings of alternating SiO4 and BO3(OH) tetrahedra with the sheets bonded together by calcium atoms.

  11. Dynamic stretching is effective as static stretching at increasing flexibility

    OpenAIRE

    Coons, John M.; Gould, Colleen E.; Kim, Jwa K.; Farley, Richard S.; Caputo, Jennifer L.

    2017-01-01

    This study examined the effect of dynamic and static (standard) stretching on hamstring flexibility. Twenty-five female volleyball players were randomly assigned to dynamic (n = 12) and standard (n = 13) stretching groups. The experimental group trained with repetitive dynamic stretching exercises, while the standard modality group trained with static stretching exercises. The stretching interventions were equivalent in the time at stretch and were performed three days a week for four weeks. ...

  12. Vibrations in deformed nuclei

    International Nuclear Information System (INIS)

    Aprahamian, A.

    1992-01-01

    Quadrupole oscillations around a deformed shape give rise to vibrations in deformed nuclei. Single phonon vibrations of K = 0 (β) and K = 2 (γ) are a systematic feature in deformed nuclei, but the existence of multi-phonon vibrations had remained an open question until the recently reported results in 168 Er. In this nucleus, a two-phonon K = 4(γγ) band was observed at approximately 2.5 times the energy of the single γ vibration. The authors have studied several deformed rare-earth nuclei using the ( 4 He,2n) reaction in order to map out the systematic behavior of these multi-phonon vibrations. Recently, they have identified a similar K = 4 band in 154 Gd

  13. Vibrational spectroscopic study of the copper silicate mineral ajoite (K,Na)Cu7AlSi9O24(OH)6·3H2O

    Science.gov (United States)

    Frost, Ray L.; Xi, Yunfei

    2012-06-01

    Ajoite (K,Na)Cu7AlSi9O24(OH)6·3H2O is a mineral named after the Ajo district of Arizona. Raman and infrared spectroscopy were used to characterise the molecular structure of ajoite. The structure of the mineral shows disorder which is reflected in the difficulty of obtaining quality Raman spectra. The Raman spectrum is characterised by a broad spectral profile with a band at 1048 cm-1 assigned to the ν1 (A1g) symmetric stretching vibration. Strong bands at 962, 1015 and 1139 cm-1 are assigned to the ν3 SiO4 antisymmetric stretching vibrations. Multiple ν4 SiO4 vibrational modes indicate strong distortion of the SiO4 tetrahedra. Multiple AlO and CuO stretching bands are observed. Raman spectroscopy and confirmed by infrared spectroscopy clearly shows that hydroxyl units are involved in the ajoite structure. Based upon the infrared spectra, water is involved in the ajoite structure, probably as zeolitic water.

  14. Biocatalysis: Unmasked by stretching

    Science.gov (United States)

    Kharlampieva, Eugenia; Tsukruk, Vladimir V.

    2009-09-01

    The biocatalytic activity of enzyme-loaded responsive layer-by-layer films can be switched on and off by simple mechanical stretching. Soft materials could thus be used to trigger biochemical reactions under mechanical action, with potential therapeutic applications.

  15. The vibrational Jahn–Teller effect in E⊗e systems

    Energy Technology Data Exchange (ETDEWEB)

    Thapaliya, Bishnu P.; Dawadi, Mahesh B.; Ziegler, Christopher; Perry, David S., E-mail: dperry@uakron.edu

    2015-10-16

    Highlights: • The vibrational Jahn–Teller effect is documented for three E⊗e molecular systems. • The spontaneous vibrational Jahn–Teller distortion is very small. • Vibrational Jahn–Teller splittings are substantial (1–60 cm{sup −1}). • Vibrational conical intersections in CH{sub 3}OH are accessible at low energies. - Abstract: The Jahn–Teller theorem is applied in the vibrational context where degenerate high-frequency vibrational states (E) are considered as adiabatic functions of low-frequency vibrational coordinates (e). For CH{sub 3}CN and Cr(C{sub 6}H{sub 6})(CO){sub 3}, the global minimum of the non-degenerate electronic potential energy surface occurs at the C{sub 3v} geometry, but in CH{sub 3}OH, the equilibrium geometry is far from the C{sub 3v} reference geometry. In the former cases, the computed spontaneous Jahn–Teller distortion is exceptionally small. In methanol, the vibrational Jahn–Teller interaction results in the splitting of the degenerate E-type CH stretch into what have been traditionally assigned as the distinct ν{sub 2} and ν{sub 9} vibrational bands. The ab initio vibrational frequencies are fit precisely by a two-state high-order Jahn–Teller Hamiltonian (Viel and Eisfeld, 2004). The presence of vibrational conical intersections, including 7 for CH{sub 3}OH, has implications for spectroscopy, for geometric phase, and for ultrafast localized non-adiabatic energy transfer.

  16. Novel stretch-sensor technology allows quantification of adherence and quality of home-exercises

    DEFF Research Database (Denmark)

    Rathleff, Michael Skovdal; Bandholm, Thomas Quaade; Ahrendt, Peter

    2014-01-01

    OBJECTIVE: To investigate if a new stretch sensor attached to an elastic exercise band can assist health professionals in evaluating adherence to home exercises. More specifically, the study investigated whether health professionals can differentiate elastic band exercises performed as prescribed...

  17. Vibrational properties of water molecules adsorbed in different zeolitic frameworks

    International Nuclear Information System (INIS)

    Crupi, V; Longo, F; Majolino, D; Venuti, V

    2006-01-01

    The perturbation of water 'sorbed' in samples of zeolites of different structural type, genesis, and cation composition (K-, Na-, Mg- and Ca-rich zeolites), namely the CHA framework of a synthetic K-chabazite, the LTA framework of synthetic Na-A and Mg50-A zeolites, and the NAT framework of a natural scolecite, has been studied by FTIR-ATR spectroscopy, in the -10 to +80 o C temperature range. The aim was to show how differences in the chemical composition and/or in the topology of the zeolite framework and, in particular, the possibility for the guest water molecules to develop guest-guest and/or host-guest interactions, lead to substantial differences in their vibrational dynamical properties. The spectra, collected in the O-H stretching and H 2 O bending mode regions, are complex, with multiple bands being observed. As far as water in the CHA and LTA frameworks is concerned, whose behaviour is governed by the balance of water-water, water-framework and water-extra-framework cations interactions, the assignment of the resolved components of the O-H stretching band has been discussed by fitting the band shapes into individual components attributed to H 2 O molecules engaged in different degrees of hydrogen bonding. A detailed quantitative picture of the connectivity pattern of water, as a function of temperature and according to the chemical and topological properties of the environment, is furnished. The H 2 O bending vibrational bands give additional information that perfectly agrees with the results obtained from the analysis of the O-H stretching spectral region. In the case of scolecite, a small-pored zeolite where water-water interactions are eliminated, the increased complexity observed in the infrared spectra in the O-H stretching and H 2 O bending regions was explained as due to the hydrogen bonding between the water molecules and the network, and also with the extra-framework cation. Furthermore, these observations have been correlated with the different

  18. Relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons (Conference Presentation)

    Science.gov (United States)

    Simpkins, Blake S.; Fears, Kenan P.; Dressick, Walter J.; Dunkelberger, Adam D.; Spann, Bryan T.; Owrutsky, Jeffrey C.

    2016-09-01

    Coherent coupling between an optical transition and confined optical mode have been investigated for electronic-state transitions, however, only very recently have vibrational transitions been considered. Here, we demonstrate both static and dynamic results for vibrational bands strongly coupled to optical cavities. We experimentally and numerically describe strong coupling between a Fabry-Pérot cavity and carbonyl stretch ( 1730 cm 1) in poly-methylmethacrylate and provide evidence that the mixed-states are immune to inhomogeneous broadening. We investigate strong and weak coupling regimes through examination of cavities loaded with varying concentrations of a urethane monomer. Rabi splittings are in excellent agreement with an analytical description using no fitting parameters. Ultrafast pump-probe measurements reveal transient absorption signals over a frequency range well-separated from the vibrational band, as well as drastically modified relaxation rates. We speculate these modified kinetics are a consequence of the energy proximity between the vibration-cavity polariton modes and excited state transitions and that polaritons offer an alternative relaxation path for vibrational excitations. Varying the polariton energies by angle-tuning yields transient results consistent with this hypothesis. Furthermore, Rabi oscillations, or quantum beats, are observed at early times and we see evidence that these coherent vibration-cavity polariton excitations impact excited state population through cavity losses. Together, these results indicate that cavity coupling may be used to influence both excitation and relaxation rates of vibrations. Opening the field of polaritonic coupling to vibrational species promises to be a rich arena amenable to a wide variety of infrared-active bonds that can be studied in steady state and dynamically.

  19. Observation of Combination Bands Involving Intermolecular Vibrations of N_2O-N_2, N_2O-OCS and N_2O-CO_2 Complexes Using AN External Cavity Quantum Cascade Laser

    Science.gov (United States)

    Rezaei, M.; Sheybani-Deloui, S.; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2013-06-01

    Spectra of the weakly-bound N_2O-CO_2, N_2O-OCS, and N_2O-N_2 complexes in the region of the N_2O ν_1 fundamental band (˜2224 cm^{-1}) are observed in a pulsed supersonic slit jet expansion probed with a quantum cascade laser. One new band is observed for each complex: two combination bands involving the intermolecular in-plane bending for N_2O-CO_2 and N_2O-N_2 complexes, and the out-of-plane torsional vibration for N_2O-OCS. The resulting intermolecular frequencies are 34.17, 17.11 and 22.33 cm^{-1} for N_2O-CO_2, N_2O-OCS, and N_2O-N_2 complexes, respectively. The intermolecular vibrations provide clear spectroscopic data against which theory can be benchmarked. These results will be discussed, along with a brief introduction to our pulsed-jet supersonic apparatus which has been retrofitted by an infrared cw external-cavity quantum cascade laser (QCL) manufactured by Daylight Solutions. The QCL is used in the rapid-scan signal averaging mode. Although the repetition rate of the QCL is limited by its PZT scan rate, which is 100 Hz, we describe a simple technique to increase the effective repetition rate to 625 Hz. In addition, we have significantly reduced the long term frequency drift of the QCL by locking the laser frequency to the sides of a reference line. Limin Zheng, Soo-Ying Lee, Yunpeng Lu, and Minghui Yang, J. Chem. Phys. 138, 044302 (2013).

  20. SOLVENT SENSITIVITY OF THE WAVE-NUMBER CHARACTERIZING THE CARBONYL STRETCHING VIBRATION OF N-CYCLOHEXYL-2-PYRROLIDINONE DISSOLVED IN PURE LIQUIDS AND IN MIXTURES FORMED BY HEXANE AND DEUTERIOTRICHLOROMETHANE AT 298.2-K

    NARCIS (Netherlands)

    ENGBERTS, JBFN; PERJESSY, A; BLANDAMER, MJ

    1993-01-01

    The dependence of nuBAR(C=O) on solvent for N-cyclohexyl-2-pyrrolidinone (NCP) as solute in 18 pure solvents can be described using a two-parameter equation based on the Taft-Kamlet pi* (dipolarity/polarisability) and alpha proton donor parameters. In alcoholic solvents two bands are recorded, the

  1. Fundamental and combination bands of CO2-C2H2 and CO2-C2D2 in the mid-infrared region

    Science.gov (United States)

    Rezaei, M.; George, J.; Welbanks, L.; Moazzen-Ahmadi, N.

    2014-09-01

    Spectra of the weakly bound CO2-C2H2 and CO2-C2D2 complexes are observed in the regions of CO2 ν3 (≈ 2349 cm-1) and C2D2 ν3 (≈ 2440 cm-1) fundamental vibrations, using an infrared optical parametric oscillator to probe a pulsed supersonic slit-jet expansion. Five bands are measured and analysed: the fundamental asymmetric stretch of the C2D2 component, two combination bands involving the out-of-plane torsional vibrations (C2D2 ν3 + torsion and CO2 ν3 + torsion) for CO2-C2D2, and two combination bands involving an intermolecular in-plane bending vibration for CO2-C2H2 and CO2-C2D2. The resulting intermolecular frequencies are 61.408(1), 54.5(5), 39.9(5), and 39.961(1) cm-1 for CO2-C2H2 and CO2-C2D2 in-plane vibrations, and CO2-C2D2 out-of-plane torsional vibrations in CO2 and C2D2 regions, respectively. This is the first experimental determination of these intermolecular vibrational frequencies.

  2. Gas Sensor Based on Photonic Crystal Fibres in the 2ν3 and ν2 + 2ν3 Vibrational Bands of Methane

    Directory of Open Access Journals (Sweden)

    Jose M. Lopez-Higuera

    2009-08-01

    Full Text Available In this work, methane detection is performed on the 2ν3 and ν2 + 2ν3 absorption bands in the Near-Infrared (NIR wavelength region using an all-fibre optical sensor. Hollowcore photonic bandgap fibres (HC-PBFs are employed as gas cells due to their compactness, good integrability in optical systems and feasibility of long interaction lengths with gases. Sensing in the 2ν3 band of methane is demonstrated to achieve a detection limit one order of magnitude better than that of the ν2 + 2ν3 band. Finally, the filling time of a HC-PBF is demonstrated to be dependent on the fibre length and geometry.

  3. Stretching & Flexibility: An Interactive Encyclopedia of Stretching. [CD-ROM].

    Science.gov (United States)

    2002

    This CD-ROM offers 140 different stretches in full-motion video sequences. It focuses on the proper techniques for overall physical fitness, injury prevention and rehabilitation, and 23 different sports (e.g., golf, running, soccer, skiing, climbing, football, and baseball). Topics include stretching for sports; stretching awareness and education…

  4. Resonant interaction between hydrogen vibrational modes in AlSb:Se.

    Science.gov (United States)

    McCluskey, M D

    2009-04-03

    Vibrational modes and their interactions affect numerous physical processes in condensed-matter systems. In the present work, hydrogen vibrations in Se-doped AlSb were investigated with first-principles calculations. Vibrational frequencies were calculated for the longitudinal, transverse, wag (bending), and stretch modes of the Al-H complex. The Al-H stretch mode interacts with a combination mode involving a wag overtone and transverse fundamental. This resonant interaction yields vibrational states that are linear superpositions of the stretch mode and the combination mode. The spatial extent of such excitations is significantly larger than that of a local vibrational mode.

  5. Experimental and theoretical study of the vibrational properties of diaspore (α-AlOOH)

    Science.gov (United States)

    Delattre, Simon; Balan, Etienne; Lazzeri, Michele; Blanchard, Marc; Guillaumet, Maxime; Beyssac, Olivier; Haussühl, Eiken; Winkler, Björn; Salje, Ekhard K. H.; Calas, Georges

    2012-02-01

    Vibrational properties of diaspore, α-AlOOH, have been re-investigated using room-temperature single-crystal Raman spectroscopy and low-temperature powder infrared (IR) transmission spectroscopy. First-principles harmonic calculations based on density functional theory provide a convincing assignment of the major Raman peaks and infrared absorption bands. The large width of the Raman band related to OH stretching modes is ascribed to mode-mode anharmonic coupling due to medium-strength H-bonding. Additional broadening in the powder IR spectrum arises from depolarization effects in powder particles. The temperature dependence of the IR spectrum provides a further insight into the anharmonic properties of diaspore. Based on their frequency and temperature behavior, narrow absorption features at ~2,000 cm-1 and anti-resonance at ~2,966 cm-1 in the IR spectrum are interpreted as overtones of fundamental bending bands.

  6. Hydrogen local vibrational modes in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    McCluskey, Matthew D. [Univ. of California, Berkeley, CA (United States). Dept. of Physics

    1997-06-01

    Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, and anti-crossing is observed between LVM and phonon modes.

  7. Hydrogen local vibrational modes in semiconductors

    Science.gov (United States)

    McCluskey, Matthew Douglas

    Following a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient, exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen, the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the (111) direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, an anti-crossing is observed between the LVM and phonon modes.

  8. Stretching the Border

    DEFF Research Database (Denmark)

    Horstmann, Alexander

    2014-01-01

    In this paper, I hope to add a complementary perspective to James Scott’s recent work on avoidance strategies of subaltern mountain people by focusing on what I call the refugee public. The educated Karen elite uses the space of exile in the Thai borderland to reconstitute resources and to re-ent......-based organizations succeed to stretch the border by establishing a firm presence that is supported by the international humanitarian economy in the refugee camps in Northwestern Thailand....

  9. High-resolution infrared spectroscopy of CH2D79Br: ro-vibrational analysis of the ν4 and ν8 fundamental bands

    DEFF Research Database (Denmark)

    Stoppa, P.; Visinoni, R.; Baldacci, A.

    2017-01-01

    The high-resolution Fourier transform infrared spectrum of CH2D79Br has been recorded and analysed in the region of the ν4 and ν8 fundamentals located in the range 1125−1360 cm−1. The strong ν4 band, centred at 1225 cm−1, shows an a/b-hybrid structure with predominant a-type character, whereas ν8...

  10. Quantum chemistry-based analysis of the vibrational spectra of five-coordinate metalloporphyrins [M(TPP)Cl].

    Science.gov (United States)

    Paulat, Florian; Praneeth, V K K; Näther, Christian; Lehnert, Nicolai

    2006-04-03

    Vibrational properties of the five-coordinate porphyrin complexes [M(TPP)(Cl)] (M = Fe, Mn, Co) are analyzed in detail. For [Fe(TPP)(Cl)] (1), a complete vibrational data set is obtained, including nonresonance (NR) Raman, and resonance Raman (RR) spectra at multiple excitation wavelengths as well as IR spectra. These data are completely assigned using density functional (DFT) calculations and polarization measurements. Compared to earlier works, a number of bands are reassigned in this one. These include the important, structure-sensitive band at 390 cm(-1), which is reassigned here to the totally symmetric nu(breathing)(Fe-N) vibration for complex 1. This is in agreement with the assignments for [Ni(TPP)]. In general, the assignments are on the basis of an idealized [M(TPP)]+ core with D(4h) symmetry. In this Work, small deviations from D(4h) are observed in the vibrational spectra and analyzed in detail. On the basis of the assignments of the vibrational spectra of 1, [Mn(TPP)(Cl)] (2), and diamagnetic [Co(TPP)(Cl)] (3), eight metal-sensitive bands are identified. Two of them correspond to the nu(M-N) stretching modes with B(1g) and Eu symmetries and are assigned here for the first time. The shifts of the metal sensitive modes are interpreted on the basis of differences in the porphyrin C-C, C-N, and M-N distances. Besides the porphyrin core vibrations, the M-Cl stretching modes also show strong metal sensitivity. The strength of the M-Cl bond in 1-3 is further investigated. From normal coordinate analysis (NCA), force constants of 1.796 (Fe), 0.932 (Mn), and 1.717 (Co) mdyn/A are obtained for 1-3, respectively. The weakness of the Mn-Cl bond is attributed to the fact that it only corresponds to half a sigma bond. Finally, RR spectroscopy is used to gain detailed insight into the nature of the electronically excited states. This relates to the mechanism of resonance enhancement and the actual nature of the enhanced vibrations. It is of importance that anomalous

  11. Kontrola kvalitete stretch folije

    OpenAIRE

    Gržanić, Nino

    2016-01-01

    U završnom radu opisan je postupak ekstrudiranja i kontrole kvalitete stretch folije koji se koristi u firmi Bomark-Pak radi osiguravanja najbolje kvalitete. Kontrola kreče kod uvoza repromaterijala, nastavlja se kod izrade folije na stroju, te se glavni dio odvija nakon izrade gotovg proizvoda. U radu ćemo detaljno objasniti svaki pojedini korak, zašto se on vrši, te uz pomoć kojih mjernih instrumenata se izvršava.

  12. Vibrational spectrum of CF4 isotopes in an algebraic model

    Indian Academy of Sciences (India)

    n this paper the stretching vibrational modes of CF4 isotopes are calculated up to first overtone using the one-dimensional vibron model for the first time. The model Hamiltonian so constructed seems to describe the C–F stretching modes accurately using a relatively small set of well-defined parameters.

  13. Microwave and Submillimeter-Wave Measurements of HD 12C 16O in the ν 4, ν 5, and ν 6 Bands: Evidence of Vibrational Induced Rotational Axis Switching ("VIRAS")

    Science.gov (United States)

    Perrin, A.; Flaud, J.-M.; Margulès, L.; Demaison, J.; Mäder, H.; Wörmke, S.

    2002-12-01

    The rotational spectrum of HDCO in the 4 1, 5 1, and 6 1 excited vibrational states has been investigated in Lille and Kiel using a sample enriched in deuterium. In Lille, the measurements were performed in the millimeter region (160-600 GHz). The spectra in Kiel were recorded using Fourier transform microwave spectrometers in the regions around 8-18 and 18-26 GHz, employing a rectangular waveguide of length 12 m and a circular waveguide of length 36 m, respectively. These results were combined with the 4 1, 5 1, and 6 1 infrared energy levels which were obtained from a previous analysis of FTS spectra of the ν 4 (CHD bend), ν 5 (CHD rocking), and ν 6 bands (out of plane bend) recorded in the 10-μm region at Giessen (A. Perrin, J.-M. Flaud, M. Smirnov, and M. Lock, J. Mol. Spectrosc.203, 175-187 (2000)). The energy level calculation of the 4 1, 5 1, and 6 1 interacting states accounts for the usual A- and B-type Coriolis resonances in the 5 1⇔6 1 and 4 1⇔6 1 off diagonals blocks. In addition, since the energy levels of the 5 1 and 6 1 states are very strongly resonating, it proved necessary, as in our previous study, to use a { Jx, Jz} nonorthorhombic term in the 5 1 and 6 1v-diagonal blocks of the Hamiltonian matrix in order to reproduce properly the observed microwave transitions and infrared energy levels. Therefore, this work confirms that HDCO is a good example of the vibrational induced rotational axis switching ("VIRAS") effect.

  14. Doppler-limited high-resolution spectrum and VPT2 assisted assignment of the C-H stretch of CH2Br2.

    Science.gov (United States)

    Sadiek, Ibrahim; Friedrichs, Gernot

    2017-06-15

    The Doppler limited non-saturated rotationally resolved infrared spectra of the symmetric and asymmetric CH-stretch bands of CH 2 Br 2 have been measured. A continuous wave cavity ringdown setup with a widely tunable Mid-IR-OPO laser light source yielded a single-shot minimum absorption of 4.9×10 -8 cm -1 . In contrast to the heavily congested ν 1 band, the ν 6 band showed partially resolved rotational features that may serve as suitable absorption targets in future environmental detection schemes for CH 2 Br 2 . A straightforward, VPT2 (second-order vibrational perturbation theory) assisted quantum-chemical approach for assigning the rotational structure has been tested using different model chemistries. The molecular structures, anharmonic frequencies and the structural changes upon vibrational excitation of CH 2 Br 2 have been investigated. The predicted changes of the anharmonic rotational constants have been used together with available spectroscopic ground state constants to simulate the rovibrational structures of the ν 1 and ν 6 bands of CH 2 Br 2 . A refined analysis of the ν 6 band is presented yielding accurate values for the band origin and the rotational constants. A fit of the line positions of 312 prominent transitions of the three isotopologues revealed a low standard error of 0.00056cm -1 , hence within the absolute 0.0009cm -1 wavelength accuracy of the used spectrometer setup. A combined analysis of the predicted line strengths and positions of the strong Q sub-branches of the ν 6 band has been performed to test the ability of the different density functionals for VPT2 prediction of anharmonic molecular constants. The M06/6-311++G(d,p) model chemistry turned out to yield reliable state-dependent rotational constants that are accurate enough to reproduce the overall rotational structure even without fitting. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Infrared spectroscopy of flavones and flavonols. Reexamination of the hydroxyl and carbonyl vibrations in relation to the interactions of flavonoids with membrane lipids

    Science.gov (United States)

    Baranović, Goran; Šegota, Suzana

    2018-03-01

    Detailed vibrational assignments for twelve flavonoids (seven flavones (flavone, 3- and 5-hydroxyflavone, chrysin, apigenin, fisetin and luteolin) and five flavonols (galangin, kaempferol, quercetin, morin and myricetin)) have been made based on own and reported experimental data and calculations at the B3LYP/6-31 + G(d,p) level of theory. All the molecules are treated in a uniform way by using the same set of redundancy-free set of internal coordinates. A generalized harmonic mode mixing is used to corroborate the vibrational characteristics of this important class of molecules. Each flavonoid molecule can be treated from the vibrational point of view as made of relatively weakly coupled chromone and phenyl part. It has been shown that the strongest band around 1600 cm- 1 need not be attributable to the Cdbnd O stretching. The way the vibrations of any of the hydroxyl groups are mixed with ring vibrations and vibrations of other neighboring hydroxyl groups is rather involved. This imposes severe limitations on any attempt to describe normal modes of a flavonol in terms of hydroxyl or carbonyl group vibrations. The role of water molecules in the appearance of flavonoid IR spectra is emphasized. Knowing for the great affinity of phosphate groups in lipids towards water, the immediate consequence is a reasonable assumption that flavonoid lipid interactions is mediated by water.

  16. An infrared study of carbon monoxide complexes of hemocyanins. Evidence for the structure of the CO-binding site from vibrational analysis

    International Nuclear Information System (INIS)

    Deen, H. van der; Hoving, H.

    1979-01-01

    A vibrational analysis was carried out showing that the infrared experimental data of 13 C and 18 O carbon monoxide complexes of hemocyanin of Fager and Alben (Biochemistry 11 (1972) 4786) are consistent with a coordination of the carbon atom of CO to one of the two copper ions in the active site. This conclusion contradicts the original interpretation of Fager and Alben in which oxygen-coordination to copper was suggested. This vibrational analysis can also be applied to the study of Alben and Caughey (Biochemistry 7 (1968) 175) with 13 C and 18 O carbonyl hemoglobin, in which oxygen-coordination to iron was suggested. Carbonyl hemocyanins from several sources have also been studied by infrared spectroscopy. The single stretching vibration of CO bound to arthropodal (Cancer magister) hemocyanin (γsub(CO)) is at 2042.5 cm -1 , while γsub(CO) for gastropod (Helix pomatia of the phylum Mollusca) α and β hemocyanin is at 2064.5 cm -1 and 2062.5 cm -1 , respectively. The intensities of the CO stretching bands were all around 1.5 X 10 4 M -1 cm -2 . Calculations show that with the present attainable accuracy it is impossible to detect hydrogen bonding of exchangeable protons to small molecules bound to proteins (for example CO), by comparing its stretching frequencies in H 2 O and D 2 O buffers. (Auth.)

  17. Internal vibrations in molecular crystals

    International Nuclear Information System (INIS)

    Howard, J.

    1984-01-01

    Recent developments in the understanding of the relative intensities of INS bands (polycrystalline samples) are described together with the observation of a fundamental transition at ca 380 MeV (C-H stretching mode) uncontaminated by overtone or combination bands. Recent work (>100 MeV) on strongly hydrogen bonded complexes (CrOHO and MFHF - ), which have high energy modes exhibiting significant dispersion, is also discussed

  18. Combination Bands of the Nonpolar OCS Dimer Involving Intermolecular Modes

    Science.gov (United States)

    Rezaei, M.; Oliaee, J. Norooz; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2012-06-01

    Spectra of the nonpolar carbonyl sulfide in the region of the OCS ν_1 fundamental band were observed in a supersonic slit-jet apparatus. The expansion gas was probed using radiation from a tunable diode laser employed in a rapid-scan signal averaging mode. Three bands centered at 2085.906, 2103.504, and 2114.979 cm-1 were observed and anlysed. The rotational assignment and fitting of the bands were made by fixing the lower state parameters to those for the ground state of nonpolar (OCS)_2, thus confirming that they were indeed combination bands of the of the most stable isomer of OCS dimer. The band centered at 2085.906 cm-1 is a combination of the forbidden A_g intramolecular mode plus the geared bend intermolecular mode and that centered at 2114.979 cm-1 is a combination of the allowed B_u intramolecular mode plus the intermolecular van der Waals stretch. The combination at 2103.504 cm-1 can be assigned as a band whose upper state involves four quanta of the intramolecular bend or the B_u intramolecular mode plus two quanta of the intermolecular torsional mode. Isotopic work is needed to conclusively identify the vibrational assignment of this band. Our experimental frequencies for the geared bend and van der Waals modes are in good agreement with a recent high level ab initio calculation by Brown et al. J. Brown, Xiao-Gang Wang, T. Carrington Jr. and Richard Dawes, Journal of Chemical Physics, submitted.

  19. Acute effect of different stretching methods on flexibility and jumping performance in competitive artistic gymnasts.

    Science.gov (United States)

    Dallas, G; Smirniotou, A; Tsiganos, G; Tsopani, D; Di Cagno, A; Tsolakis, Ch

    2014-12-01

    The purpose of this study was to investigate the acute effects of 3 different warm up methods of stretching (static, proprioceptive neuromuscular facilitation, and stretching exercises on a Vibration platform) on flexibility and legs power-jumping performance in competitive artistic gymnasts. Eighteen competitive artistic gymnasts were recruited to participate in this study. Subjects were exposed to each of 3 experimental stretching conditions: static stretching (SS), proprioceptive neuromuscular facilitation stretching (PNF), and stretching exercises on a Vibration platform (S+V). Flexibility assessed with sit and reach test (S & R) and jumping performance with squat jump (SJ) and counter movement jump (CMJ) and were measured before, immediately after and 15 min after the interventions. Significant differences were observed for flexibility after all stretching conditions for S+V (+1.1%), SS (+5.7%) and PNF (+6.8%) (P=0.000), which remained higher 15 min after interventions (S+V (1.1%), SS (5.3%) and PNF (5.5%), respectively (P=0.000). PNF stretching increased flexibility in competitive gymnasts, while S+V maintained jumping performance when both methods were used as part of a warm-up procedure.

  20. Vibration mixer

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S.A.; Chernov, V.S.; Denisenko, V.V.; Gorodnyanskiy, I.F.; Prokopov, L.I.; Tikhonov, Yu.P.

    1983-01-01

    The vibration mixer is proposed which contains a housing, vibration drive with rod installed in the upper part of the mixing mechanism made in the form of a hollow shaft with blades. In order to improve intensity of mixing and dispersion of the mud, the shaft with the blades is arranged on the rod of the vibrator and is equipped with a cam coupling whose drive disc is attached to the vibration rod. The rod is made helical, while the drive disc of the cam coupling is attached to the helical surface of the rod. In addition, the vibration mixer is equipped with perforated discs installed on the ends of the rods.

  1. Vibrationally quantum-state-specific dynamics of the reactions of CN radicals with organic molecules in solution

    Science.gov (United States)

    Rose, Rebecca A.; Greaves, Stuart J.; Oliver, Thomas A. A.; Clark, Ian P.; Greetham, Gregory M.; Parker, Anthony W.; Towrie, Michael; Orr-Ewing, Andrew J.

    2011-06-01

    The dynamics of reactions of CN radicals with cyclohexane, d12-cyclohexane, and tetramethylsilane have been studied in solutions of chloroform, dichloromethane, and the deuterated variants of these solvents using ultraviolet photolysis of ICN to initiate a reaction. The H(D)-atom abstraction reactions produce HCN (DCN) that is probed in absorption with sub-picosecond time resolution using ˜500 cm-1 bandwidth infrared (IR) pulses in the spectral regions corresponding to C-H (or C-D) and C≡N stretching mode fundamental and hot bands. Equivalent IR spectra were obtained for the reactions of CN radicals with the pure solvents. In all cases, the reaction products are formed at early times with a strong propensity for vibrational excitation of the C-H (or C-D) stretching (v3) and H-C-N (D-C-N) bending (v2) modes, and for DCN products there is also evidence of vibrational excitation of the v1 mode, which involves stretching of the C≡N bond. The vibrationally excited products relax to the ground vibrational level of HCN (DCN) with time constants of ˜130-270 ps (depending on molecule and solvent), and the majority of the HCN (DCN) in this ground level is formed by vibrational relaxation, instead of directly from the chemical reaction. The time-dependence of reactive production of HCN (DCN) and vibrational relaxation is analysed using a vibrationally quantum-state specific kinetic model. The experimental outcomes are indicative of dynamics of exothermic reactions over an energy surface with an early transition state. Although the presence of the chlorinated solvent may reduce the extent of vibrational excitation of the nascent products, the early-time chemical reaction dynamics in these liquid solvents are deduced to be very similar to those for isolated collisions in the gas phase. The transient IR spectra show additional spectroscopic absorption features centered at 2037 cm-1 and 2065 cm-1 (in CHCl3) that are assigned, respectively, to CN-solvent complexes and

  2. Vibrational echo spectral observables and frequency fluctuations of ...

    Indian Academy of Sciences (India)

    Deepak Ojha

    Abstract. Aqueous solution of a fluoride ion at 300K is studied using the method of ab initio molecular dynamics simulation. Instantaneous fluctuations in vibrational frequencies of local OD stretch modes of deuterated water are calculated using a time-series analysis of the simulated trajectory. The vibrational spectral.

  3. Stretch-minimising stream surfaces

    KAUST Repository

    Barton, Michael

    2015-05-01

    We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these \\'stretch-free\\' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

  4. High resolution FTIR spectroscopy of sulfur dioxide in the 1550-1950 cm-1 region: First analysis of the ν1 +ν2 /ν2 +ν3 bands of 32S16O18O and experimental line intensities of ro-vibrational transitions in the ν1 +ν2 /ν2 +ν3 bands of 32S16O2, 34S16O2, 32S18O2 and 32S16O18O

    Science.gov (United States)

    Ulenikov, O. N.; Bekhtereva, E. S.; Gromova, O. V.; Horneman, V.-M.; Sydow, C.; Bauerecker, S.

    2017-12-01

    The high resolution infrared spectra of the 32S16O18O molecule were recorded for the first time with a Bruker IFS 120 HR Fourier transform interferometer and analysed in the region of 1550-1950 cm-1 where the bands ν1 +ν2 and ν2 +ν3 are located. About 1050 and 1570 transitions were assigned in the experimental spectra with the maximum values of quantum numbers Jmax. / Kamax . equal to 64/16 and 58/19 to the bands ν1 +ν2 and ν2 +ν3 , respectively. The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account the resonance interactions between the studied vibrational states. As the result, a set of 16 fitted parameters was obtained which reproduces the initial 1442 ro-vibrational energy values obtained from the assigned transitions with the drms = 3.7 ×10-4cm-1 . An analysis of more than 4050 experimental ro-vibrational line intensities of the ν1 +ν2 and ν2 +ν3 bands of 32S16O2 was made, and a set of 7 effective dipole moment parameters was obtained which reproduce the initial experimental line intensities with the drms = 6.9 % . Values of these parameters, being re-calculated to the values of corresponding parameters of the 34S16O2, 32S18O2 and 32S16O18O species were used for calculation of line intensities in the ν1 +ν2 and ν2 +ν3 bands of these three isotopologues. A list of transitions with their line intensities in the region of 1550-1950 cm-1 for the four mentioned species is generated.

  5. Experimental and theoretical model of reactivity and vibrational detection modes of triacetone triperoxide (TATP) and homologues

    Science.gov (United States)

    Pacheco-Londono, Leonardo C.; Primera-Pedrozo, Oliva M.; Hernandez-Rivera, Samuel P.

    2004-12-01

    Fully optimized molecular geometry, parameters of reactivity and vibrational spectra of triacetone triperoxide (TATP) and homologue organic peroxides were calculated using B3LYP/6-31G(d,p) method within the Density Functional Theory formalism. Infrared and Raman Spectroscopy were utilized to obtain vibrational spectra of the energetic compound. The model consists in the relation found between the Raman Shift location of the important symmetric stretch ν(O-O) of the organic peroxides and the reactivity of the organic peroxides. A good correlation between the band location in the series studied and the x-y plane polarizability component and the ionization energy was found. Gas phase IR absorption of TATP in air was used for developing stand-off detection schemes of the important organic peroxide in air. The sublimation properties of TATP were measured using two methods: Grazing Angle Probe-Fiber Coupled FTIR and gravimetric on stainless steel surfaces. Sublimation rates, loading concentration values and absorbance band areas were measured and modeled using the persistent IR vibrational signature of the ν(C-O) mode.

  6. Acute Muscle Stretching and Shoulder Position Sense

    OpenAIRE

    Björklund, Martin; Djupsjöbacka, Mats; Crenshaw, Albert G

    2006-01-01

    Context: Stretching is common among athletes as a potential method for injury prevention. Stretching-induced changes in the muscle spindle properties are a suggested mechanism, which may imply reduced proprioception after stretching; however, little is known of this association.

  7. High resolution spectroscopy of jet cooled phenyl radical: The ν1 and ν2 a1 symmetry C-H stretching modes

    Science.gov (United States)

    Chang, Chih-Hsuan; Nesbitt, David J.

    2016-07-01

    A series of CH stretch modes in phenyl radical (C6H5) has been investigated via high resolution infrared spectroscopy at sub-Doppler resolution (˜60 MHz) in a supersonic discharge slit jet expansion. Two fundamental vibrations of a1 symmetry, ν1 and ν2, are observed and rotationally analyzed for the first time, corresponding to in-phase and out-of-phase symmetric CH stretch excitation at the ortho/meta/para and ortho/para C atoms with respect to the radical center. The ν1 and ν2 band origins are determined to be 3073.968 50(8) cm-1 and 3062.264 80(7) cm-1, respectively, which both agree within 5 cm-1 with theoretical anharmonic scaling predictions based on density functional B3LYP/6-311g++(3df,3dp) calculations. Integrated band strengths for each of the CH stretch bands are analyzed, with the relative intensities agreeing remarkably well with theoretical predictions. Frequency comparison with previous low resolution Ar-matrix spectroscopy [A. V. Friderichsen et al., J. Am. Chem. Soc. 123, 1977 (2001)] reveals a nearly uniform Δν ≈ + 10-12 cm-1 blue shift between gas phase and Ar matrix values for ν1 and ν2. This differs substantially from the much smaller red shift (Δν ≈ - 1 cm-1) reported for the ν19 mode, and suggests a simple physical model in terms of vibrational mode symmetry and crowding due to the matrix environment. Finally, the infrared phenyl spectra are well described by a simple asymmetric rigid rotor Hamiltonian and show no evidence for spectral congestion due to intramolecular vibrational coupling, which bodes well for high resolution studies of other ring radicals and polycyclic aromatic hydrocarbons. In summary, the combination of slit jet discharge methods with high resolution infrared lasers enables spectroscopic investigation of even highly reactive combustion and interstellar radical intermediates under gas phase, jet-cooled (Trot ≈ 11 K) conditions.

  8. CH Stretching Region: Computational Modeling of Vibrational Optical Activity

    Czech Academy of Sciences Publication Activity Database

    Hudecová, Jana; Profant, V.; Novotná, P.; Baumruk, V.; Urbanová, M.; Bouř, Petr

    2013-01-01

    Roč. 9, č. 7 (2013), s. 3096-3108 ISSN 1549-9618 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:AV ČR(CZ) M200550902 Institutional support: RVO:61388963 Keywords : density-functional theory * circular-dichroism spectra * N-methyl acetamide * alpha-pinene * Raman Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.310, year: 2013

  9. Vibrations of stretched damped beams under non-ideal boundary ...

    Indian Academy of Sciences (India)

    A simply supported damped Euler–Bernoulli beam with immovable end conditions are considered. The concept of non-ideal boundary conditions is applied to the beam problem. In accordance, the boundaries are assumed to allow small deflections and moments. Approximate analytical solution of the problem is found ...

  10. Vibrational spectroscopic analysis of taranakite (K,NH4)Al3(PO4)3(OH)·9(H2O) from the Jenolan Caves, Australia.

    Science.gov (United States)

    Frost, Ray L; Xi, Yunfei; Palmer, Sara J; Pogson, Ross E

    2011-12-01

    Many phosphate containing minerals are found in the Jenolan Caves. Such minerals are formed by the reaction of bat guano and clays from the caves. Among these cave minerals is the mineral taranakite (K,NH(4))Al(3)(PO(4))(3)(OH)·9(H(2)O) which has been identified by X-ray diffraction. Jenolan Caves taranakite has been characterised by Raman spectroscopy. Raman and infrared bands are assigned to H(2)PO(4), OH and NH stretching vibrations. By using a combination of XRD and Raman spectroscopy, the existence of taranakite in the caves has been proven. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Line Mixing in Parallel and Perpendicular Bands of CO2: A Further Test of the Refined Robert-Bonamy Formalism

    Science.gov (United States)

    Boulet, C.; Ma, Qiancheng; Tipping, R. H.

    2015-01-01

    Starting from the refined Robert-Bonamy formalism [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)], we propose here an extension of line mixing studies to infrared absorptions of linear polyatomic molecules having stretching and bending modes. The present formalism does not neglect the internal degrees of freedom of the perturbing molecules, contrary to the energy corrected sudden (ECS) modeling, and enables one to calculate the whole relaxation matrix starting from the potential energy surface. Meanwhile, similar to the ECS modeling, the present formalism properly accounts for roles played by all the internal angular momenta in the coupling process, including the vibrational angular momentum. The formalism has been applied to the important case of CO2 broadened by N2. Applications to two kinds of vibrational bands (sigma yields sigma and sigma yields pi) have shown that the present results are in good agreement with both experimental data and results derived from the ECS model.

  12. Hydraulic fracture during epithelial stretching.

    Science.gov (United States)

    Casares, Laura; Vincent, Romaric; Zalvidea, Dobryna; Campillo, Noelia; Navajas, Daniel; Arroyo, Marino; Trepat, Xavier

    2015-03-01

    The origin of fracture in epithelial cell sheets subject to stretch is commonly attributed to excess tension in the cells' cytoskeleton, in the plasma membrane, or in cell-cell contacts. Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension. We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres. After pressure equilibration, cracks heal readily through actomyosin-dependent mechanisms. The observed phenomenology is captured by the theory of poroelasticity, which predicts the size and healing dynamics of epithelial cracks as a function of the stiffness, geometry and composition of the hydrogel substrate. Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics.

  13. Soleus stretch reflex during cycling

    DEFF Research Database (Denmark)

    Grey, Michael James; Pierce, C. W.; Milner, T. E.

    2001-01-01

    the crank cycle, producing ankle dorsiflexion perturbations of similar trajectory. The stretch reflex was greatest during the power phase of the crank cycle and was decreased to the level of background EMG during recovery. Matched perturbations were induced under static conditions at the same crank angle...... active cycling as has been shown with the H-reflex. This lack of depression may reflect a decreased susceptibility of the stretch reflex to inhibition, possibly originating from presynaptic mechanisms....

  14. Relationship Between Stretch Duration And Shoulder Musculature ...

    African Journals Online (AJOL)

    To date, studies focussing on the effect of stretching on flexibility have focused almost solely on the effect of chronic stretching rather than the effects of acute stretching performed immediately prior to physical activity. The effects of different static stretches were assessed on passive shoulder range of motion (ROM).

  15. Atomic Stretch: Optimally bounded real-time stretching and beyond

    DEFF Research Database (Denmark)

    Jensen, Rasmus Ramsbøl; Nielsen, Jannik Boll

    2016-01-01

    Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color-modification, co......Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color...

  16. High-Resolution Rovibrational Spectroscopy of Jet-Cooled Phenyl Radical: The ν19 Out-of-Phase Symmetric CH Stretch

    Science.gov (United States)

    Buckingham, Grant T.; Chang, Chih-Hsuan; Nesbitt, David J.

    2013-10-01

    Phenyl radical has been studied via sub-Doppler infrared spectroscopy in a slit supersonic discharge expansion source, with assignments for the highest frequency b2 out-of-phase C-H symmetric stretch vibration (-19) unambiguously confirmed by ≤6 MHz (0.0002 cm-1) agreement with microwave ground state combination differences of McMahon et al. [Astrophys. J. 2003, 590, L61-64]. Least squares analysis of over 100 resolved rovibrational peaks in the sub-Doppler spectrum to a Watson Hamiltonian yields precision excited-state rotational constants and a vibrational band origin (-0 = 3071.8915(4) cm-1) consistent with a surprisingly small red-shift (0.9 cm-1) with respect to Ar matrix isolation studies of Ellison and co-workers [J. Am. Chem. Soc. 2001, 123, 1977]. Nuclear spin weights and inertial defects confirm the vibrationally averaged planarity and 2A1 rovibronic symmetry of phenyl radical, with analysis of the rotational constants consistent with a modest C2v distortion of the carbon backbone frame due to partial sp rehybridization of the σ C radical-center. Most importantly, despite the number of atoms (N = 11) and vibrational modes (3N - 6 = 27), phenyl radical exhibits a remarkably clean jet cooled high-resolution IR spectrum that shows no evidence of intramolecular vibrational relaxation (IVR) phenomena such as local or nonlocal perturbations due to strongly coupled nearby dark states. This provides strong support for the feasibility of high-resolution infrared spectroscopy in other aromatic hydrocarbon radical systems.

  17. High Resolution Rovibrational Spectroscopy of Jet-Cooled Phenyl Radical: the ν_{19} Out-Of Symmetric C-H Stretch

    Science.gov (United States)

    Buckingham, Grant T.; Chang, Chih-Hsuan; Nesbitt, David J.

    2013-06-01

    Phenyl radical has been studied via sub-Doppler infrared spectroscopy in a slit supersonic discharge expansion source, with assignments for the highest frequency b_{2} out-of-phase C-H symmetric stretch vibration (ν_{19}) unambiguously confirmed by ≤ 6 MHz (0.0002 cm^{-1}) agreement with microwave ground state combination differences of McMahon et al. [Astrophys. J. 590, L61-64 (2003)]. Least squares analysis of > 100 resolved rovibrational peaks in the sub-Doppler spectrum to a Watson Hamiltonian yields precision exited-state rotational constants and a vibrational band origin (ν_{0} = 3071.8915(4) cm^{-1}) consistent with a surprisingly small red-shift (0.9 cm^{-1}) with respect to Ar matrix isolation studies of Ellison and coworkers [J. Am. Chem. Soc. 123, 1977 (2001)]. Nuclear spin weights and inertial defects confirm the vibrationally averaged planarity and ^{2}A_{1} rovibronic symmetry of phenyl radical, with analysis of the rotational constants consistent with a modest C_{2v} distortion of the carbon backbone frame due to partial sp rehybridization of the σ C radical-center. Most importantly, despite the number of atoms (N = 11) and vibrational modes (3N-6 = 27), phenyl radical exhibits a remarkably clean jet cooled high resolution IR spectrum that shows no evidence of intramolecular vibrational relaxation (IVR) phenomena such as local or non-local perturbations due to strongly coupled nearby dark states. This provides strong support for the feasibility of high resolution infrared spectroscopy in other cyclic aromatic hydrocarbon radical systems.

  18. Broadband Vibration Attenuation Using Hybrid Periodic Rods

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2008-12-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of a broadband vibration isolator. It is a table-like system formed by four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a system, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the "Pass Bands" and wave propagation is efficiently attenuated within other frequency bands called the "Stop Bands". The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. This concept can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  19. Multiple Rabi Splittings under Ultrastrong Vibrational Coupling.

    Science.gov (United States)

    George, Jino; Chervy, Thibault; Shalabney, Atef; Devaux, Eloïse; Hiura, Hidefumi; Genet, Cyriaque; Ebbesen, Thomas W

    2016-10-07

    From the high vibrational dipolar strength offered by molecular liquids, we demonstrate that a molecular vibration can be ultrastrongly coupled to multiple IR cavity modes, with Rabi splittings reaching 24% of the vibration frequencies. As a proof of the ultrastrong coupling regime, our experimental data unambiguously reveal the contributions to the polaritonic dynamics coming from the antiresonant terms in the interaction energy and from the dipolar self-energy of the molecular vibrations themselves. In particular, we measure the opening of a genuine vibrational polaritonic band gap of ca. 60 meV. We also demonstrate that the multimode splitting effect defines a whole vibrational ladder of heavy polaritonic states perfectly resolved. These findings reveal the broad possibilities in the vibrational ultrastrong coupling regime which impact both the optical and the molecular properties of such coupled systems, in particular, in the context of mode-selective chemistry.

  20. Acute effects of unilateral static stretching on handgrip strength of the stretched and non-stretched limb.

    Science.gov (United States)

    Jelmini, Jacob D; Cornwell, Andrew; Khodiguian, Nazareth; Thayer, Jennifer; Araujo, And John

    2018-02-16

    To determine the effects of an acute bout of unilateral static stretching on handgrip strength of both the stretched and non-stretched limb. It was reasoned that if the non-stretched limb experienced a decrease in force output, further evidence for a neural mechanism to explain a post-stretch force reduction would be obtained as no mechanical adaptation would have occurred. Thirty participants performed maximum voluntary unilateral handgrip contractions of both limbs before and after stretching the finger flexors of the strength-dominant side only. Each trial was assessed for peak force, muscle activity (iEMG), and rate of force generation. Following the stretching bout, peak force and iEMG decreased by 4.4% (p = 0.001) and 6.4% (p = 0.000) respectively in the stretched limb only. However, rate of force generation was significantly impaired in both the stretched (- 17.3%; p = 0.000) and non-stretched limbs (- 10.8%; p = 0.003) 1 min post-stretch, and remained similarly depressed for both limbs 15 min later. Acute stretching negatively impacts rate of force generation more than peak force. Moreover, a reduced rate of force generation from the non-stretched limb indicates the presence of a cross-over inhibitory effect through the nervous system, which provides additional evidence for a neural mechanism.

  1. Vibrational spectroscopic analysis of the mineral crandallite CaAl3(PO4)2(OH)5·(H2O) from the Jenolan Caves, Australia.

    Science.gov (United States)

    Frost, Ray L; Xi, Yunfei; Palmer, Sara J; Pogson, Ross

    2011-11-01

    The mineral crandallite CaAl(3)(PO(4))(2)(OH)(5)·(H(2)O) has been identified in deposits found in the Jenolan Caves, New South Wales, Australia by using a combination of X-ray diffraction and Raman spectroscopic techniques. A comparison is made between the vibrational spectra of crandallite found in the Jenolan Caves and a standard crandallite. Raman and infrared bands are assigned to PO(4)(3-) and HPO(4)(2-) stretching and bending modes. The predominant features are the internal vibrations of the PO(4)(3-) and HPO(4)(2-) groups. A mechanism for the formation of crandallite is presented and the conditions for the formation are elucidated. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Soleus stretch reflex during cycling

    DEFF Research Database (Denmark)

    Grey, Michael James; Pierce, C. W.; Milner, T. E.

    2001-01-01

    The modulation and strength of the human soleus short latency stretch reflex was investigated by mechanically perturbing the ankle during an unconstrained pedaling task. Eight subjects pedaled at 60 rpm against a preload of 10 Nm. A torque pulse was applied to the crank at various positions durin...

  3. On the generalised stretch function

    Czech Academy of Sciences Publication Activity Database

    Kharlamov, Alexander A.; Filip, Petr

    2012-01-01

    Roč. 21, č. 4 (2012), s. 272-278 ISSN 1022-1344 R&D Projects: GA ČR GA103/09/2066 Institutional research plan: CEZ:AV0Z20600510 Keywords : molecular length * recurrence equations * rubber * strain * stretch functions Subject RIV: BK - Fluid Dynamics Impact factor: 1.606, year: 2012

  4. Optical tweezers stretching of chromatin

    NARCIS (Netherlands)

    Pope, L.H.; Bennink, Martin L.; Greve, Jan

    2003-01-01

    Recently significant success has emerged from exciting research involving chromatin stretching using optical tweezers. These experiments, in which a single chromatin fibre is attached by one end to a micron-sized bead held in an optical trap and to a solid surface or second bead via the other end,

  5. Transient filament stretching rheometer II

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1997-01-01

    The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

  6. Biaxial stretching of polyethylene, (2)

    International Nuclear Information System (INIS)

    Sakami, Hiroshi; Iida, Shozo

    1976-01-01

    The mechanism of oriented crystallization in mutually perpendicular direction to each other was investigated on the crosslinked linear polyethylene stretched successively and biaxially above melting point of raw material. To investigate the mechanism, the shrinkage stress, the degree of polarization and DSC of the film at the fixed length were measured on the crystallization process. The behavior observed on crystallization could be divided into that in the first period and that in the second period. The first period showed the domain of highly oriented crystallization of the crosslinked molecular chain, and in the second period the fold type crystals grew with highly oriented crystals in the first period as nuclear. Therefore, the formation of bi-component crystal structure is supposed for the crystallization. The biaxially oriented crystallization proceeded as follows: the uniaxial orientation to MD was observed in the first stretching in the initial stage, and then the further processing by the second stretching at a right angle caused the fold type crystallization of molecular chain oriented to TD. The film stretched fully and biaxially could be considered to have the oriented crystalline structure in which highly oriented fibril crystals and fold type crystals distribute at random. (auth.)

  7. Intramolecular Vibrational Energy Transfer and Bond-Selected Photochemistry in Liquids

    National Research Council Canada - National Science Library

    Crim, F

    2001-01-01

    .... In the gas phase experiments, one pulse excited the first overtone of the O-H stretching vibration in nitric acid and the second pulse probed the excited molecule by excitation to a dissociative...

  8. Effects of static-stretching and whole-body-vibration during warm-ups on bench-press kinematics in males and females college-aged. [Efectos de los estiramientos estáticos y vibraciones durante el calentamiento en los parámetros cinemáticos del press banca en hombres y mujeres estudiantes].

    Directory of Open Access Journals (Sweden)

    Esperanza Martín-Santana

    2015-10-01

    Full Text Available This study aimed to examine the effects of different specific warm-up protocols including static stretching (SS and whole body vibrations (WBV on kinematics and number of repetitions during a bench press set to failure in physically active male and female subjects. A secondary purpose was to analyze the role of sex on the warm-up induced effects. 24 participants (13 females and 11 males were randomly assigned to complete 3 experimental conditions in a cross-over design: SS, WBV and SS+WBV. After each condition, participants performed one bench-press set to volitional exhaustion with a load equivalent to the 60% of one-repetition maximum (1RM. No significant differences (P>0.05 were observed in number of repetitions, mean and maximal accelerative portion (AP, mean and maximal velocity, and lifting velocity time-course pattern. Males showed significantly higher values regarding number of repetitions achieved and maximal and mean lifting velocity. However, regarding the percentage of the concentric phase in which barbell is accelerated, there were no sex differences. In conclusion, no relevant difference in kinematics variables can be shown when applying any of these three different warm-up protocols, these results may be useful when designing training programs. We recommend the protocol SS due to the cost-benefit relationship. Resumen El objetivo de este estudio fue examinar el efecto de diferentes protocolos de calentamiento incluyendo estiramientos estáticos (EE y vibraciones de cuerpo entero (WBV en variables cinemáticas y número de repeticiones completadas en una serie de press banca realizada hasta el fallo muscular, en hombres y mujeres físicamente activos. Un segundo objetivo fue analizar el papel de la variable sexo en los efectos inducidos por el calentamiento. 24 participantes (13 mujeres y 11 hombres completaron, de forma aleatoria, 3 condiciones experimentales con un diseño cruzado: EE, WBV, y EE+WBV. Al terminar cada protocolo de

  9. [Structure analysis of disease-related proteins using vibrational spectroscopy].

    Science.gov (United States)

    Hiramatsu, Hirotsugu

    2014-01-01

    Analyses of the structure and properties of identified pathogenic proteins are important for elucidating the molecular basis of diseases and in drug discovery research. Vibrational spectroscopy has advantages over other techniques in terms of sensitivity of detection of structural changes. Spectral analysis, however, is complicated because the spectrum involves a substantial amount of information. This article includes examples of structural analysis of disease-related proteins using vibrational spectroscopy in combination with additional techniques that facilitate data acquisition and analysis. Residue-specific conformation analysis of an amyloid fibril was conducted using IR absorption spectroscopy in combination with (13)C-isotope labeling, linear dichroism measurement, and analysis of amide I band features. We reveal a pH-dependent property of the interacting segment of an amyloidogenic protein, β2-microglobulin, which causes dialysis-related amyloidosis. We also reveal the molecular mechanisms underlying pH-dependent sugar-binding activity of human galectin-1, which is involved in cell adhesion, using spectroscopic techniques including UV resonance Raman spectroscopy. The decreased activity at acidic pH was attributed to a conformational change in the sugar-binding pocket caused by protonation of His52 (pKa 6.3) and the cation-π interaction between Trp68 and the protonated His44 (pKa 5.7). In addition, we show that the peak positions of the Raman bands of the C4=C5 stretching mode at approximately 1600 cm(-1) and the Nπ-C2-Nτ bending mode at approximately 1405 cm(-1) serve as markers of the His side-chain structure. The Raman signal was enhanced 12 fold using a vertical flow apparatus.

  10. Conformational, vibrational and DFT studies of a newly synthesized arylpiperazine-based drug and evaluation of its reactivity towards the human GABA receptor

    Science.gov (United States)

    Onawole, A. T.; Al-Ahmadi, A. F.; Mary, Y. S.; Panicker, C. Y.; Ullah, N.; Armaković, S.; Armaković, S. J.; Van Alsenoy, C.; Al-Saadi, A. A.

    2017-11-01

    This study reports a computational assessment of important biochemical properties and vibrational assignments for the synthesized 1-(4-(3-methoxy-4-nitrophenyl)piperazin-1-yl)ethanone (MNPE). MNPE is related to the commonly used arylpiperazine-based drugs that exhibit a wide range of pharmacological activities. The characterization of MNPE is based on the readily sighted 1363 cm-1 infrared band (associated with piperazine ring stretching), 1308 cm-1 Raman line (associated with the phenyl ring breathing), 1242 cm-1 Raman line and 1092 cm-1 infrared band (both associated with Csbnd N stretching) as key modes in its vibrational spectra. First principle calculations revealed that MNPE could exist in sixteen different plausible conformations, which were used as basis to understand the possible molecular docking mechanism of the molecule as an agonist in the human GABAA receptor. The best binding scenarios showed the presence of intramolecular hydrogen bonding in MNPE and was comparable with the most stable configuration. It was further evaluated for its reactivity properties by utilizing the concepts of Average Local Ionization Energies (ALIE) and Fukui functions. The autoxidation and hydrolysis degradation likelihood of MNPE estimated from the computed bond dissociation energies and radial distribution functions predicted that MNPE is to be readily biodegradable in aqueous solutions.

  11. To Stretch and Search for Better Ways

    Science.gov (United States)

    Moore, John W.

    2000-06-01

    There's a lot to do to get each issue of this Journal ready for publication, and there's a lot that can go awry during that process. We the editorial staff do our utmost to make certain that each issue is the best it can possibly be, but, of necessity, a lot of our effort is focused on solving problems, correcting errors, and avoiding pitfalls. It is not surprising that we sometimes lose sight of the bigger picture--all of the things that came out as well as or better than we hoped they would. Therefore it gives us great pleasure when a reader applauds (and thereby rewards) our efforts. One such communication inspired this editorial. I have appreciated the extra effort put forward by the staff to make the Journal really come alive. The high quality of the Journal serves as an incentive to chemical educators to stretch and search for better ways to inspire our students. I fervently hope that we do encourage you "to stretch and search for better ways", not only to inspire students but in everything you do. Stretching and searching for better ways is what life, science, chemistry, and teaching are all about, and it is a wonderfully stimulating and exciting way to approach anything and everything. Sometimes, though, one's ability to stretch is akin to that of a rubber band exposed too long to sunlight. Change becomes a threat or a burden instead of an opportunity. This often happens in one area but not others, as in the case of someone doing original research but whose lecture notes are yellow with age, or someone who experiments with new teaching approaches but neglects the latest chemical discoveries. Whatever its manifestation, failure to stretch and search for better ways is a great loss, both for the individual directly involved and for others. Fortunately there are many who continually stretch and search, often in conjunction with JCE. For example, some time ago the Chair of the Board of Publication, Jerry Bell, challenged Journal readers to become Journal

  12. The vibrational spectrum of alpha-AlOOH diaspore: an ab initio study with the CRYSTAL code.

    Science.gov (United States)

    Demichelis, R; Noel, Y; Civalleri, B; Roetti, C; Ferrero, M; Dovesi, R

    2007-08-09

    The vibrational spectrum of alpha-AlOOH diaspore has been calculated at the B3LYP level of theory with a double-zeta quality Gaussian-type basis set by using the periodic ab initio CRYSTAL code. Harmonic frequencies at the Gamma point and the corresponding 48 normal modes are analyzed and classified in terms of simple models (octahedra modes, hydrogen stretching, bending, rotations) by direct inspection of eigenvectors, graphical representation, and isotopic substitution. Hydrogen modes are fully separated from the octahedra modes appearing under 800 cm(-1); bending modes are located in the range of 1040-1290 cm(-1), whereas stretching modes appear at 3130-3170 cm(-1). The available experimental IR and Raman spectra are characterized by broad bands, in some cases as large as 800 cm(-1), and individual peaks are obtained by decomposing these bands in terms of Lorentz-Gauss product functions; such a fitting procedure is affected by a relatively large degree of arbitrariness. The comparison of our calculated data with the most complete sets of experimental data shows, nevertheless, a relatively good agreement for all but the H modes; the mean absolute differences for modes not involving H are 10.9 and 7.2 cm(-1) for the IR and the Raman spectra, respectively, the maximum differences being 15.5 and 18.2 cm(-1). For the H bending modes, differences increase to 30 and 37 cm(-1), and for the stretching modes, the calculated frequencies are about 200 cm(-1) higher than the experimental ones; this is not surprising, as anharmonicity is expected to red shift the OH stretching by about 150 cm(-1) in isolated OH groups and even more when the latter is involved in strong hydrogen bonds, as is the case here.

  13. Vibrational spectroscopy and principal component analysis for conformational study of virus nucleic acids

    Science.gov (United States)

    Dovbeshko, G. I.; Repnytska, O. P.; Pererva, T.; Miruta, A.; Kosenkov, D.

    2004-07-01

    Conformation analysis of mutated DNA-bacteriophages (PLys-23, P23-2, P47- the numbers have been assigned by T. Pererva) induced by MS2 virus incorporated in Ecoli AB 259 Hfr 3000 has been done. Surface enhanced infrared absorption (SEIRA) spectroscopy and principal component analysis has been applied for solving this problem. The nucleic acids isolated from the mutated phages had a form of double stranded DNA with different modifications. The nucleic acid from phage P47 was undergone the structural rearrangement in the most degree. The shape and position ofthe fine structure of the Phosphate asymmetrical band at 1071cm-1 as well as the stretching OH vibration at 3370-3390 cm-1 has indicated to the appearance ofadditional OH-groups. The Z-form feature has been found in the base vibration region (1694 cm-1) and the sugar region (932 cm-1). A supposition about modification of structure of DNA by Z-fragments for P47 phage has been proposed. The P23-2 and PLys-23 phages have showed the numerous minor structural changes also. On the basis of SEIRA spectra we have determined the characteristic parameters of the marker bands of nucleic acid used for construction of principal components. Contribution of different spectral parameters of nucleic acids to principal components has been estimated.

  14. On the Lowest Ro-Vibrational States of Protonated Methane: Experiment and Analytical Model

    Science.gov (United States)

    Schmiedt, Hanno; Jensen, Per; Asvany, Oskar; Schlemmer, Stephan

    2016-06-01

    Protonated methane, CH_5^+, is the prototype of an extremely floppy molecule. To the best of our knowledge all barriers are surmountable in the rovibrational ground state; the large amount of zero-point vibrational energy leads to large amplitude motions for many degrees of freedom. Low resolution but broad band vibrational spectroscopy [1] revealed an extremely wide range of C-H stretching vibrations. Comparison with theoretical IR spectra supported the structural motif of a CH_3 tripod and an H_2 moiety, bound to the central carbon atom by a 3c2e bond. In a more dynamic picture the five protons surround the central carbon atom without significant restrictions on the H-C-H bending or H_n-C torsional motions. The large-amplitude internal motions preclude a simple theoretical description of the type possible for more conventional molecules, such as the related spherical-top methane molecule. Recent high-resolution ro-vibrational spectra obtained in cold ion trap experiments [2] show that the observed CH_5^+ transitions belong to a very well-defined energy level scheme describing the lowest rotational and vibrational states of this enigmatic molecule. Here we analyse the experimental ground state combination differences and associate them with the motional states of CH_5^+ allowed by Fermi-Dirac statistics. A model Hamiltonian for unrestricted internal rotations in CH_5^+ yields a simple analytical expression for the energy eigenvalues, expressed in terms of new quantum numbers describing the free internal rotation. These results are compared to the experimental combination differences and the validity of the model will be discussed together with the underlying assumptions. [1] O. Asvany, P. Kumar, I. Hegemann, B. Redlich, S. Schlemmer and D. Marx, Science 309, (2005) 1219-1222 [2] O. Asvany, K.M.T. Yamada, S. Brünken, A. Potapov, S. Schlemmer, Science 347 (2015) 1346-1349

  15. Solution and solid trinitrotoluene (TNT) photochemistry: persistence of TNT-like ultraviolet (UV) resonance Raman bands.

    Science.gov (United States)

    Gares, Katie L; Bykov, Sergei V; Godugu, Bhaskar; Asher, Sanford A

    2014-01-01

    We examined the 229 nm deep-ultraviolet resonance Raman (DUVRR) spectra of solution and solid-state trinitrotoluene (TNT) and its solution and solid-state photochemistry. Although TNT photodegrades with a solution quantum yield of ϕ ∼ 0.015, the initial photoproducts show DUVRR spectra extraordinarily similar to pure TNT, due to the similar photoproduct enhancement of the -NO2 stretching vibrations. This results in TNT-like DUVRR spectra even after complete TNT photolysis. These ultraviolet resonance Raman spectral bands enable DUVRR of trace as well as DUVRR standoff TNT detection. We determined the structure of various initial TNT photoproducts by using liquid chromatography-mass spectrometry and tandem mass spectrometry. Similar TNT DUVRR spectra and photoproducts are observed in the solution and solid states.

  16. New investigation of the ν3 C-H stretching region of 12CH4 through the analysis of high temperature infrared emission spectra.

    Science.gov (United States)

    Amyay, Badr; Gardez, Aline; Georges, Robert; Biennier, Ludovic; Vander Auwera, Jean; Richard, Cyril; Boudon, Vincent

    2018-04-07

    The ν 3 C-H stretching region of methane was reinvestigated in this work using high temperature (620-1715 K) emission spectra recorded in Rennes at Doppler limited resolution. This work follows our recent global analysis of the Dyad system Δn = ±1 (1000-1500 cm -1 ), with n being the polyad number [B. Amyay et al., J. Chem. Phys. 144, 24312 (2016)]. Thanks to the high temperature, new assignments of vibration-rotation methane line positions have been achieved successfully in the Pentad system and some associated hot bands (Δn = ±2) observed in the spectral region 2600-3300 cm -1 . In particular, rotational assignments in the cold band [Pentad-ground state (GS)] and in the first related hot band (Octad-Dyad) were extended up to J = 30 and 27, respectively. In addition, 1525 new transitions belonging to the Tetradecad-Pentad hot band system were assigned for the first time, up to J = 20. The effective global model used to deal with the new assignments was developed to the 6th order for the first three polyads (Monad, Dyad, and Pentad), and to the 5th order for both the Octad and the Tetradecad. 1306 effective parameters were fitted with a dimensionless standard deviation σ = 2.64. The root mean square deviations d RMS obtained are 4.18 × 10 -3 cm -1 for the Pentad-GS cold band, 2.48 × 10 -3 cm -1 for the Octad-Dyad, and 1.43 × 10 -3 cm -1 for the Tetradecad-Pentad hot bands.

  17. Molecular couplings and energy exchange between DNA and water mapped by femtosecond infrared spectroscopy of backbone vibrations

    Directory of Open Access Journals (Sweden)

    Yingliang Liu

    2017-07-01

    Full Text Available Molecular couplings between DNA and water together with the accompanying processes of energy exchange are mapped via the ultrafast response of DNA backbone vibrations after OH stretch excitation of the water shell. Native salmon testes DNA is studied in femtosecond pump-probe experiments under conditions of full hydration and at a reduced hydration level with two water layers around the double helix. Independent of their local hydration patterns, all backbone vibrations in the frequency range from 940 to 1120 cm–1 display a quasi-instantaneous reshaping of the spectral envelopes of their fundamental absorption bands upon excitation of the water shell. The subsequent reshaping kinetics encompass a one-picosecond component, reflecting the formation of a hot ground state of the water shell, and a slower contribution on a time scale of tens of picoseconds. Such results are benchmarked by measurements with resonant excitation of the backbone modes, resulting in distinctly different absorption changes. We assign the fast changes of DNA absorption after OH stretch excitation to structural changes in the water shell which couple to DNA through the local electric fields. The second slower process is attributed to a flow of excess energy from the water shell into DNA, establishing a common heated ground state in the molecular ensemble. This interpretation is supported by theoretical calculations of the electric fields exerted by the water shell at different temperatures.

  18. Time stretch and its applications

    Science.gov (United States)

    Mahjoubfar, Ata; Churkin, Dmitry V.; Barland, Stéphane; Broderick, Neil; Turitsyn, Sergei K.; Jalali, Bahram

    2017-06-01

    Observing non-repetitive and statistically rare signals that occur on short timescales requires fast real-time measurements that exceed the speed, precision and record length of conventional digitizers. Photonic time stretch is a data acquisition method that overcomes the speed limitations of electronic digitizers and enables continuous ultrafast single-shot spectroscopy, imaging, reflectometry, terahertz and other measurements at refresh rates reaching billions of frames per second with non-stop recording spanning trillions of consecutive frames. The technology has opened a new frontier in measurement science unveiling transient phenomena in nonlinear dynamics such as optical rogue waves and soliton molecules, and in relativistic electron bunching. It has also created a new class of instruments that have been integrated with artificial intelligence for sensing and biomedical diagnostics. We review the fundamental principles and applications of this emerging field for continuous phase and amplitude characterization at extremely high repetition rates via time-stretch spectral interferometry.

  19. Triceps surae short latency stretch reflexes contribute to ankle stiffness regulation during human running.

    Directory of Open Access Journals (Sweden)

    Neil J Cronin

    Full Text Available During human running, short latency stretch reflexes (SLRs are elicited in the triceps surae muscles, but the function of these responses is still a matter of controversy. As the SLR is primarily mediated by Ia afferent nerve fibres, various methods have been used to examine SLR function by selectively blocking the Ia pathway in seated, standing and walking paradigms, but stretch reflex function has not been examined in detail during running. The purpose of this study was to examine triceps surae SLR function at different running speeds using Achilles tendon vibration to modify SLR size. Ten healthy participants ran on an instrumented treadmill at speeds between 7 and 15 km/h under 2 Achilles tendon vibration conditions: no vibration and 90 Hz vibration. Surface EMG from the triceps surae and tibialis anterior muscles, and 3D lower limb kinematics and ground reaction forces were simultaneously collected. In response to vibration, the SLR was depressed in the triceps surae muscles at all speeds. This coincided with short-lasting yielding at the ankle joint at speeds between 7 and 12 km/h, suggesting that the SLR contributes to muscle stiffness regulation by minimising ankle yielding during the early contact phase of running. Furthermore, at the fastest speed of 15 km/h, the SLR was still depressed by vibration in all muscles but yielding was no longer evident. This finding suggests that the SLR has greater functional importance at slow to intermediate running speeds than at faster speeds.

  20. BSDB: the Biomolecule Stretching Database

    Science.gov (United States)

    Cieplak, Marek; Sikora, Mateusz; Sulkowska, Joanna I.; Witkowski, Bartlomiej

    2011-03-01

    Despite more than a decade of experiments on single biomolecule manipulation, mechanical properties of only several scores of proteins have been measured. A characteristic scale of the force of resistance to stretching, Fmax , has been found to range between ~ 10 and 480 pN. The Biomolecule Stretching Data Base (BSDB) described here provides information about expected values of Fmax for, currently, 17 134 proteins. The values and other characteristics of the unfolding proces, including the nature of identified mechanical clamps, are available at www://info.ifpan.edu.pl/BSDB/. They have been obtained through simulations within a structure-based model which correlates satisfactorily with the available experimental data on stretching. BSDB also lists experimental data and results of the existing all-atom simulations. The database offers a Protein-Data-Bank-wide guide to mechano-stability of proteins. Its description is provided by a forthcoming Nucleic Acids Research paper. Supported by EC FUNMOL project FP7-NMP-2007-SMALL-1, and European Regional Development Fund: Innovative Economy (POIG.01.01.02-00-008/08).

  1. Vibrational spectroscopy and analysis of pseudo-tetrahedral complexes with metal imido bonds.

    Science.gov (United States)

    Mehn, Mark P; Brown, Steven D; Jenkins, David M; Peters, Jonas C; Que, Lawrence

    2006-09-04

    A number of assignments have been previously posited for the metal-nitrogen stretch (nu(M-NR)), the N-R stretch (nu(MN-R)), and possible ligand deformation modes associated with terminally bound imides. Here we examine mononuclear iron(III) and cobalt(III) imido complexes of the monoanionic tridentate ligand [PhBP3] ([PhBP3] = [PhB(CH2PPh2)3]-) to clarify the vibrational features for these trivalent metal imides. We report the structures of [PhBP3]FeNtBu and [PhBP3]CoNtBu. Pseudo-tetrahedral metal imides of these types exhibit short bond lengths (ca. 1.65 A) and nearly linear angles about the M-N-C linkages, indicative of multiple bond character. Furthermore, these compounds give rise to intense, low-energy visible absorptions. Both the position and the intensity of the optical bands in the [PhBP3]MNR complexes depend on whether the substituent is an alkyl or aryl group. Excitation into the low-energy bands of [PhBP3]FeNtBu gives rise to two Raman features at 1104 and 1233 cm(-1), both of which are sensitive to 15N and 2H labeling. The isotope labeling suggests the 1104 cm(-1) mode has the greatest Fe-N stretching character, while the 1233 cm(-1) mode is affected to a lesser extent by (15)N substitution. The spectra of the deuterium-labeled imides further support this assertion. The data demonstrate that the observed peaks are not simple diatomic stretching modes but are extensively coupled to the vibrations of the ancillary organic group. Therefore, describing these complexes as simple diatomic or even triatomic oscillators is an oversimplification. Analogous studies of the corresponding cobalt(III) complex lead to a similar set of isotopically sensitive resonances at 1103 and 1238 cm(-1), corroborating the assignments made in the iron imides. Very minimal changes in the vibrational frequencies are observed upon replacement of cobalt(III) for iron(III), suggesting similar force constants for the two compounds. This is consistent with the previously proposed

  2. Stretching

    Science.gov (United States)

    ... this topic for: Teens Dehydration Safety Tips: Running Knee Injuries Repetitive Stress Injuries Sports and Exercise Safety Dealing With Sports Injuries Sports Center Strains and Sprains View more Partner Message About Us Contact Us ...

  3. Vibrating minds

    CERN Multimedia

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  4. Vibrational spectroscopy

    Science.gov (United States)

    Umesh P. Agarwal; Rajai Atalla

    2010-01-01

    Vibrational spectroscopy is an important tool in modern chemistry. In the past two decades, thanks to significant improvements in instrumentation and the development of new interpretive tools, it has become increasingly important for studies of lignin. This chapter presents the three important instrumental methods-Raman spectroscopy, infrared (IR) spectroscopy, and...

  5. Vibrational spectroscopy of Cm–C/Cb–Cb stretching vibrations of ...

    Indian Academy of Sciences (India)

    A comprehensive treatment to understand the spectroscopic features of microsize molecules is by far one of the most challenging aspects of current studies in chem- ical physics problems [1]. On the one side, experimental techniques are producing a rapidly increasing amount of data and clear evidence for intriguing ...

  6. Tunable Mechanical Filter for Longitudinal Vibrations

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2007-01-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of vibration isolator called tunable mechanical filter which consists of four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a filter, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the “Pass Bands” and wave propagation is efficiently attenuated within other frequency bands called the “Stop Bands”. The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. The concept of this mechanical filter as presented can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  7. Effect of stretching techniques on hamstring flexibility in female ...

    African Journals Online (AJOL)

    Flexibility can be achieved by a variety of stretching techniques and the benefits of stretching are known. However, controversy remains about the best type of stretching for achieving a particular goal or outcome. The four most basic stretches are static stretching, dynamic stretching, PNF hold-relax and PNF contract-relax ...

  8. Bending and stretching of plates

    CERN Document Server

    Mansfield, E H; Hemp, W S

    1964-01-01

    The Bending and Stretching of Plates deals with elastic plate theory, particularly on small- and large-deflexion theory. Small-deflexion theory concerns derivation of basic equations, rectangular plates, plates of various shapes, plates whose boundaries are amenable to conformal transformation, plates with variable rigidity, and approximate methods. Large-deflexion theory includes general equations and some exact solutions, approximate methods in large-deflexion theory, asymptotic large-deflexion theories for very thin plates. Asymptotic theories covers membrane theory, tension field theory, a

  9. Stretching of macromolecules and proteins

    International Nuclear Information System (INIS)

    Strick, T R; Dessinges, M-N; Charvin, G; Dekker, N H; Allemand, J-F; Bensimon, D; Croquette, V

    2003-01-01

    In this paper we review the biophysics revealed by stretching single biopolymers. During the last decade various techniques have emerged allowing micromanipulation of single molecules and simultaneous measurements of their elasticity. Using such techniques, it has been possible to investigate some of the interactions playing a role in biology. We shall first review the simplest case of a non-interacting polymer and then present the structural transitions in DNA, RNA and proteins that have been studied by single-molecule techniques. We shall explain how these techniques permit a new approach to the protein folding/unfolding transition

  10. Vibrational spectroscopy

    International Nuclear Information System (INIS)

    Fadini, A.

    1980-01-01

    We present 13 programs for the calculation of vibrational spectroscopic problems applied to small molecules with high symmetry. The programs are compiled for the well known programmable pocket calculator Texas Instruments SR-52. To the special problems, the mathematical formulas, input and output instructions, several numerical examples, literature and the programs with comments are given. Order n = 1: The force constants, isotopic vibrational frequencies and the vibrational amplitudes are calculated for the two mass system XY(Csub(infinitely v)). For the three mass system XY 2 (Dsub(infinitely h)) only the force constants and isotopic frequencies are calculated. Order n = 2: For the three mass systems XYZ(Csub(infinitely v)) and XY 2 (Csub(infinitely 2v)) the inverse matrices G of the kinetic energy are presented. For complete sets of data (with isotopic frequencies, Coriolis coupling constants etc.) the complete force constant matrices are calculated. For non complete sets of data one starts in most cases with diagonal force constant matrices. The complete force constant matrix F is calculated with a minimalisation approximation. The eigenvector matrices L result from the G - F - and N-matrices. The N-matrices are calculated from the G- and F-matrices or from the F- and L-matrices respectively. Order n = 3: The matrix G of the system XYZ(Csub(S)) is calculated. For higher orders n, the 'isotopic reduction method' for the calculation of single force constants of proper systems is described. (orig.) [de

  11. Anharmonic Theoretical Vibrational Spectroscopy of Polypeptides.

    Science.gov (United States)

    Panek, Paweł T; Jacob, Christoph R

    2016-08-18

    Because of the size of polypeptides and proteins, the quantum-chemical prediction of their vibrational spectra presents an exceptionally challenging task. Here, we address one of these challenges, namely, the inclusion of anharmonicities. By performing the expansion of the potential energy surface in localized-mode coordinates instead of the normal-mode coordinates, it becomes possible to calculate anharmonic vibrational spectra of polypeptides efficiently and reliably. We apply this approach to calculate the infrared, Raman, and Raman optical activity spectra of helical alanine polypeptides consisting of up to 20 amino acids. We find that while anharmonicities do not alter the band shapes, simple scaling procedures cannot account for the different shifts found for the individual bands. This closes an important gap in theoretical vibrational spectroscopy by making it possible to quantify the anharmonic contributions and opens the door to a first-principles calculation of multidimensional vibrational spectra.

  12. Structural information from OH stretching frequencies—V. On the presence of different rotamers in substituted tertiary cyclohexanol compounds

    NARCIS (Netherlands)

    Lutz, E.T.G.; Maas, J.H. van der

    1980-01-01

    The presence of different hydroxyl rotamers in a number of saturated aequatorial and axial tertiary cyclohexanols has been studied by means of the i.r. spectra of the OH stretching band. Band resolving experiments indicate that an OH positioned over a cyclohexylring contributes appreciably to the

  13. Translational vibrations between chains of hydrogen-bonded molecules in solid-state aspirin form I

    Science.gov (United States)

    Takahashi, Masae; Ishikawa, Yoichi

    2013-06-01

    We perform dispersion-corrected first-principles calculations, and far-infrared (terahertz) spectroscopic experiments at 4 K, to examine translational vibrations between chains of hydrogen-bonded molecules in solid-state aspirin form I. The calculated frequencies and relative intensities reproduce the observed spectrum to accuracy of 11 cm-1 or less. The stronger one of the two peaks assigned to the translational mode includes the stretching vibration of the weak hydrogen bond between the acetyl groups of a neighboring one-dimensional chain. The calculation of aspirin form II performed for comparison gives the stretching vibration of the weak hydrogen bond in one-dimensional chain.

  14. Preparative conditions and vibrational study of HUP : phase transition and conductivity mechanisms

    International Nuclear Information System (INIS)

    Thi, M.P.; Novak, A.; Colomban, Ph.

    1985-01-01

    Among solid protonic conductors HUP (H 3 OUO 2 PO 4 .3 H 2 O) exhibits very high conducting properties. Uranyl/phosphate hydrates belonging to the HUP family (HUP ; UO 2 (H 2 PO 4 ) 2 .3 H 2 O ; (U= 2 ) 3 (PO 4 ) 2 .4 H 2 O ; (UO O 2 )sub(1.43)PO 4 Hsub(0.14) 2-3.5 H 2 O) have been synthesized in different forms (crystals, powders, films, ...) and characterized by various methods: chemical analysis, DTA, TGA, SEM, X-Ray diffraction, IR and Raman spectroscopy. Morphological studies reveal the presence of various particulat es, from ultrafine powders ( 2 O washing of HUP. Infrared and Raman spectra of polycrystalline H 3 OUO 2 PO 4 .3 H 2 O (HUP) have been investigated at various temperatures between 50 K and 300 K. The most temperature-sensitive bands correspond to PO 4 and H 2 O librations; U-OPO 3 stretching and OH stretching vibrations indicate four different phases of HUP and allow to propose a phasetransition mechanism from a bidimensionnal, quasi-liquid state of a protonated species in the room-temperature phase to a fully ordered crystal below 130 K. The protonic conductivity mechanism of room- and low-temperature phases is discussed. (author)

  15. Hydrogen bond dynamics and vibrational spectral diffusion in ...

    Indian Academy of Sciences (India)

    Abstract. We present an ab initio molecular dynamics study of vibrational spectral diffusion and hydrogen bond dynamics in aqueous solution of acetone at room temperature. It is found that the frequencies of OD bonds in the acetone hydration shell have a higher stretch frequency than those in the bulk water. Also, on ...

  16. Vibrational Cooling in A Cold Ion Trap: Vibrationally Resolved Photoelectron Spectroscopy of Cold C60- Anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue B.; Woo, Hin-koon; Wang, Lai S.

    2005-08-01

    We demonstrate vibrational cooling of anions via collisions with a background gas in an ion trap attached to a cryogenically controlled cold head (10 ? 400 K). Photoelectron spectra of vibrationally cold C60- anions, produced by electrospray ionization and cooled in the cold ion trap, have been obtained. Relative to spectra taken at room temperature, vibrational hot bands are completely eliminated, yielding well resolved vibrational structures and a more accurate electron affinity for neutral C60. The electron affinity of C60 is measured to be 2.683 ? 0.008 eV. The cold spectra reveal complicated vibrational structures for the transition to the C60 ground state due to the Jahn-Teller effect in the ground state of C60-. Vibrational excitations in the two Ag modes and eight Hg modes are observed, providing ideal data to assess the vibronic couplings in C60-.

  17. Two-Dimensional Electronic-Vibrational Spectroscopy of Chlorophyll a and b

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Nicholas H. C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Div.; Kavli Energy Nanoscience Institute at Berkeley, CA (United States); Fleming, Graham R. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Div.; Kavli Energy Nanoscience Institute at Berkeley, CA (United States)

    2016-03-03

    Presented are two-dimensional electronic-vibrational (2DEV) spectra of isolated chlorophyll a and b in deuterated ethanol. We excite the Q-band electronic transitions and measure the effects on the carbonyl and C=C double-bond stretch region of the infrared spectrum. With the aid of density functional theory calculations, we provide assignments for the major features of the spectrum. We show how the 2DEV spectra can be used to readily distinguish different solvation states of the chlorophyll, with features corresponding to the minority pentacoordinate magnesium (Mg) species being resolved along each dimension of the 2DEV spectra from the dominant hexacoordinate Mg species. These assignments represent a crucial first step toward the application of 2DEV spectroscopy to chlorophyll-containing pigment-protein complexes.

  18. PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION STRETCHING VERSUS STATIC STRETCHING ON SPRINTING PERFORMANCE AMONG COLLEGIATE SPRINTERS

    Directory of Open Access Journals (Sweden)

    Jayaram Maharjan

    2015-08-01

    Full Text Available Background: A warm-up is important part of preparation for sprinting. There is popularity of doing stretching as part of warm up before athletic activity. The static stretching and PNF stretching is performed by athletes but their effectiveness on sprinting performance is in state of debate. The objective is to determine the effect of static stretching and PNF stretching on sprinting performance in college sprinters and to compare the effects of PNF stretching over static stretching on sprinting performance in college sprinters. Method: A total of 100 subjects were taken for the study that fulfill the inclusion criteria and all were divided into group- A (static stretching and group- B (PNF stretching by simple random sampling method. Both the groups received 5 minutes of warm-up exercises. Pre-Post design was used, which consisted of running a 40-yard sprint immediately following 2 stretching conditions aimed at the lower limb muscles Results: In static stretching group sprint time changed from 6.55 with standard deviation of 0.93 to 6.12 with standard deviation of 1.02 (P.605. Conclusion: Hence both static stretching and PNF stretching can be performed before sprinting activity to improve the sprinting performance.

  19. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

      lab   studies   in   that   we   found   a   decreased   detection   rate   in   busy   environments.   Here   we   test   with   a   much   larger   sample   and   age   range,   and   contribute   with   the   first   vibration  sensitivity  testing  outside  the  lab  in  an  urban   public...

  20. The Far Infrared Spectrum of Thiophosgene: Analysis of the νb{2} Fundamental Band at 500 wn

    Science.gov (United States)

    McKellar, A. R. W.; Billinghurst, B. E.

    2009-06-01

    Thiophosgene (Cl_2CS) is a model system for studies of vibrational dynamics. Many hundreds of vibrational levels in the ground electronic state have been experimentally observed, allowing a detailed anharmonic force field to be developed including all six vibrational modes. But there have been no previous high resolution studies of this molecule in the infrared, presumably because its mass and multiple isotopic species result in very congested spectra. Here we report a detailed study of the strong νb{2} fundamental band (symmetric C - Cl stretch) based on a spectrum obtained using synchrotron radiation with the Bruker IFS125 FT spectrometer at the Canadian Light Source far infrared beamline. Thiophosgene is an interesting example of an accidentally near-symmetric oblate rotor. Indeed, its inertial axes switch with isotopic substitution: for ^{35}Cl_2CS, the C_{2v} symmetry axis coincides with the a inertial axis, but for ^{37}Cl_2CS, this changes to the b axis. Fortunately for us, the ground state microwave spectrum has been well studied. Even so, it has required the full spectral resolution of the present results, with observed line widths of about 0.0008 wn, to achieve a true line-by-line analysis. [1] For example: P.D. Chowdary, B. Strickler, S. Lee, and M. Gruebele, Chem. Phys. Letters 434, 182 (2007). [2] J.H. Carpenter, D.F. Rimmer, J.G. Smith, and D.H. Whiffen, J. Chem. Soc. Faraday Trans. 2 71, 1752 (1971).

  1. Contact angles on stretched solids

    Science.gov (United States)

    Mensink, Liz; Snoeijer, Jacco

    2017-11-01

    The surface energy of solid interfaces plays a central role in wetting, as they dictate the liquid contact angle. Yet, it has been challenging to measure the solid surface energies independently, without making use of Young's law. Here we present Molecular Dynamics (MD) simulations by which we measure the surface properties for all interfaces, including the solids. We observe change in contact angles upon stretching the solid substrates, showing that the surface energy is actually strain dependent. This is clear evidence of the so-called Shuttleworth effect, making it necessary to distinguish surface energy from surface tension. We discuss how this effect gives rise to a new class of elasto-capillary phenomena. ERC Consolidator Grant No. 616918.

  2. A COMPARISION BETWEEN CROSSBODY STRETCH VERSUS SLEEPER STRETCH IN PERIARTHRITIS OF SHOULDER

    Directory of Open Access Journals (Sweden)

    Shaik Raheem Saheb

    2015-12-01

    Full Text Available Background: Recently Cross body stretch and Sleeper stretch are used to improve internal rotation Range of motion in Shoulder Pathologies. It was proposed to study the effect of cross body stretch and sleeper stretch in subjects with periarthritis of shoulder. Methods: 60 subjects with a mean age of 53 years having clinical diagnosis of Periarthritis of shoulder and full filled the inclusive criteria are taken. After the initial measurements, the subjects are randomly assigned into 2 stretching groups. Group-A performed the Sleeper stretch. Group-B performed a Cross body stretch. Both Groups performed the Stretch in Duration of 6weeks – once daily for 5 repetitions holding each stretch for 30 seconds for 5 days a week. Along with this technique conventional physiotherapy like IFT, overhead pulleys, Pendula exercises, Wall climbing exercises, mariners wheel exercises are performed. After the treatment, subjects were evaluated for their pain profile using visual analogue scale, Goniometer for measuring Range of motion. Results: For within group comparison we used Paired t-test analysis, For Between group comparison we used Independent t-test for statistical analysis. At the end of 6 weeks It was found that subjects treated with cross-body stretch showed significant improvement in terms of VAS scores and Range of motion scores (P=0.000 and patients treated with Sleeper stretch showed significant improvement in terms of VAS scores and Range of motion scores (P=0.000. When compared between Groups the VAS and Range of motion scores showed a significant improvement in Cross body stretch Group than the Sleeper stretch Group (P=0.000. Conclusion: It was concluded that both stretching techniques were found improvement in Range of motion and VAS and Cross-body Stretch showed more Significant improvement than the sleeper Stretch after 6 weeks treatment.

  3. Fermi resonance and strong anharmonic effects in the absorption spectra of the ν-OH ( ν-OD) vibration of solid H- and D-benzoic acid

    Science.gov (United States)

    Yaremko, A. M.; Ratajczak, H.; Barnes, A. J.; Baran, J.; Durlak, P.; Latajka, Z.

    2009-10-01

    The vibrational spectra of polycrystalline benzoic acid (BA) and its deuterated derivative were studied over the wide frequency region 4000-10 cm -1 by IR and Raman methods. A theoretical analysis of the hydrogen bond frequency region and calculations at the B3LYP/6-311++G(2d, 2p) level for the benzoic acid cyclic dimer in the gas phase were made. In order to study the dynamics of proton transfer two formalisms were applied: Car-Parrinello Molecular Dynamics (CPMD) and Path Integrals Molecular Dynamics (PIMD). It was shown that the experimentally observed very broad ν-OH band absorption is the result of complex anharmonic interaction: Fermi resonance between the OH-stretching and bending vibrations and strong interaction of the ν-OH stretching with the low frequency phonons. The theoretical analysis in the framework of such an approach gave a good correlation with experiment. From the CPMD calculations it was confirmed that the O-H⋯O bridge is not rigid, with the O⋯O distance being described by a large amplitude motion. For the benzoic acid dimer we observed stepwise (asynchronous) proton transfer.

  4. Sub-Doppler slit jet infrared spectroscopy of astrochemically relevant cations: Symmetric (ν1) and antisymmetric (ν6) NH stretching modes in ND2H2+

    Science.gov (United States)

    Chang, Chih-Hsuan; Nesbitt, David J.

    2018-01-01

    Sub-Doppler infrared rovibrational transitions in the symmetric (v1) and antisymmetric (v6) NH stretch modes of the isotopomerically substituted ND2H2+ ammonium cation are reported for the first time in a slit jet discharge supersonic expansion spectrometer. The partially H/D substituted cation is generated by selective isotopic exchange of ND3 with H2O to form NHD2, followed by protonation with H3+ formed in the NHD2/H2/Ne slit-jet discharge expansion environment. Rotational assignment for ND2H2+ is confirmed rigorously by four line ground state combination differences, which agree to be within the sub-Doppler precision in the slit jet (˜9 MHz). Observation of both b-type (ν1) and c-type (ν6) bands enables high precision determination of the ground and vibrationally excited state rotational constants. From an asymmetric top Watson Hamiltonian analysis, the ground state constants are found to be A″ = 4.856 75(4) cm-1, B″ = 3.968 29(4) cm-1, and C″ = 3.446 67(6) cm-1, with band origins at 3297.5440(1) and 3337.9050(1) cm-1 for the v1 and v6 modes, respectively. This work permits prediction of precision microwave/mm-wave transitions, which should be invaluable in facilitating ongoing spectroscopic searches for partially deuterated ammonium cations in interstellar clouds and star-forming regions of the interstellar medium.

  5. Anharmonic Bend-Stretch Coupling in Water

    NARCIS (Netherlands)

    Lindner, Jörg; Vöhringer, Peter; Pshenichnikov, Maxim S.; Cringus, Dan; Wiersma, Douwe A.; Corkum, Paul; Jonas, David M.; Miller, R.J. Dwayne.; Weiner, Andrew M.

    2006-01-01

    Following excitation of the H-O-H bending mode of water molecules in solution the stretching mode region is monitored over its entire width. The anharmonic coupling between the two modes results in a substantial change of the transient stretch absorption that decays with the bend depopulation time.

  6. Vibrational Spectroscopy of Intramolecular Hydrogen Bonds in the Infrared and Near-Infrared Regions

    DEFF Research Database (Denmark)

    Schrøder, Sidsel Dahl

    and 1,4-diaminobutane). Experimentally, the hydrogen bonds have been studied with vibrational spectroscopy in the infrared and near-infrared regions. The focus is primarily on spectra recorded in the near-infrared regions, which in these studies are dominated by O-H and N-H stretching overtones....... Overtone spectra have been recorded with intracavity laser photoacoustic laser spectroscopy and conventional long path absorption spectroscopy. Theoretically, a combination of electronic structure calculations and local mode models have been employed to guide the assignment of bands in the vibrational......,4-diaminobutane, no sign of intramolecular N-H···N hydrogen bonds were identified in the overtone spectra. However, theoretical analyzes indicate that intramolecular N-H···N hydrogen bonds are present in all three diamines if two hydrogen atoms on one of the methylene groups are substituted with triuoromethyl...

  7. Hot Ground Vibration Tests

    Data.gov (United States)

    National Aeronautics and Space Administration — Ground vibration tests or modal surveys are routinely conducted to support flutter analysis for subsonic and supersonic vehicles. However, vibration testing...

  8. Anisotropic instability of a stretching film

    Science.gov (United States)

    Xu, Bingrui; Li, Minhao; Deng, Daosheng

    2017-11-01

    Instability of a thin liquid film, such as dewetting arising from Van der Waals force, has been well studied, and is typically characterized by formation of many droplets. Interestingly, a thin liquid film subjected to an applied stretching during a process of thermal drawing is evolved into an array of filaments, i.e., continuity is preserved along the direction of stretching while breakup occurs exclusively in the plane of cross section. Here, to understand this anisotropic instability, we build a physical model by considering both Van der Waals force and the effect of stretching. By using the linear instability analysis method and then performing a numerical calculation, we find that the growth rate of perturbations at the cross section is larger than that along the direction of stretching, resulting in the anisotropic instability of the stretching film. These results may provide theoretical guidance to achieve more diverse structures for nanotechnology.

  9. Experimental vibrational contributions to molecular hyperpolarisabilities: methods and measurements

    Science.gov (United States)

    Castiglioni, C.; Tommasini, M.; Del Zoppo, M.

    2000-03-01

    The aim of this paper is to give a simple but a complete guide to the experimental determination of vibrational molecular first and second hyperpolarisabilities from measurements of band frequencies and intensities in vibrational (IR and Raman) spectra. The approximations involved in the method are discussed and a comparison with the theoretical results is presented. A brief summary of the many applications of the "vibrational method" and a critical discussion of the problems involved are also reported.

  10. Structure and vibrations of glutathione studied by vibrational spectroscopy and density functional theory.

    Science.gov (United States)

    Singh, Gurpreet; Dogra, Sukh Dev; Kaur, Sarvpreet; Tripathi, S K; Prakash, Satya; Rai, Bimal; Saini, G S S

    2015-01-01

    The vibrational properties of glutathione have been investigated by infrared absorption and Raman spectroscopic techniques, and density functional theory calculations at the B3LYP/6-31+G(d,p) level. Assignments of all the experimentally observed vibrational bands have been done with the help of simulated vibrational spectra and potential energy distribution calculations of glutathione water cluster, which includes the effect of hydrogen bonding. Optimized molecular parameters of energy minimized structure have been compared with the available experimental values. Calculated molecular parameters of glutathione-water cluster match well with the experimental values. Some of the calculated molecular parameters and vibrational frequencies of vapor phase glutathione-water cluster suggest participation of some atoms of glutathione in hydrogen bonding. Experimentally observed UV-Visible absorption spectrum of glutathione has also been reported. Observed band at 203 nm has been assigned to electronic transitions calculated with time dependent density functional theory. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  12. Effect of CH stretching excitation on the reaction dynamics of F + CHD{sub 3} → DF + CHD{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jiayue; Zhang, Dong; Chen, Zhen; Jiang, Bo [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Blauert, Florian [Dynamics at Surfaces, Faculty of Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen (Germany); Dai, Dongxu; Wu, Guorong, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn; Zhang, Donghui; Yang, Xueming, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-07-28

    The vibrationally excited reaction of F + CHD{sub 3}(ν{sub 1} = 1) → DF + CHD{sub 2} at a collision energy of 9.0 kcal/mol is investigated using the crossed-beams and time-sliced velocity map imaging techniques. Detailed and quantitative information of the CH stretching excitation effects on the reactivity and dynamics of the title reaction is extracted with the help of an accurate determination of the fraction of the excited CHD{sub 3} reagent in the crossed-beam region. It is found that all vibrational states of the CHD{sub 2} products observed in the ground-state reaction, which mainly involve the excitation of the umbrella mode of the CHD{sub 2} products, are severely suppressed by the CH stretching excitation. However, there are four additional vibrational states of the CHD{sub 2} products appearing in the excited-state reaction which are not presented in the ground-state reaction. These vibrational states either have the CH stretching excitation retained or involve one quantum excitation in the CH stretching and the excitation of the umbrella mode. Including all observed vibrational states, the overall cross section of the excited-state reaction is estimated to be 66.6% of that of the ground-state one. Experimental results also show that when the energy of CH stretching excitation is released during the reaction, it is deposited almost exclusively as the rovibrational energy of the DF products, with little portion in the translational degree of freedom. For vibrational states of the CHD{sub 2} products observed in both ground- and excited-state reactions, the CH stretching excitation greatly suppresses the forward scattered products, causing a noticeable change in the product angular distributions.

  13. Strategy as stretch and leverage.

    Science.gov (United States)

    Hamel, G; Prahalad, C K

    1993-01-01

    Global competition is not just product versus product or company versus company. It is mind-set versus mind-set. Driven to understand the dynamics of competition, we have learned a lot about what makes one company more successful than another. But to find the root of competitiveness--to understand why some companies create new forms of competitive advantage while others watch and follow--we must look at strategic mind-sets. For many managers, "being strategic" means pursuing opportunities that fit the company's resources. This approach is not wrong, Gary Hamel and C.K. Prahalad contend, but it obscures an approach in which "stretch" supplements fit and being strategic means creating a chasm between ambition and resources. Toyota, CNN, British Airways, Sony, and others all displaced competitors with stronger reputations and deeper pockets. Their secret? In each case, the winner had greater ambition than its well-endowed rivals. Winners also find less resource-intensive ways of achieving their ambitious goals. This is where leverage complements the strategic allocation of resources. Managers at competitive companies can get a bigger bang for their buck in five basic ways: by concentrating resources around strategic goals; by accumulating resources more efficiently; by complementing one kind of resource with another; by conserving resources whenever they can; and by recovering resources from the market-place as quickly as possible. As recent competitive battles have demonstrated, abundant resources can't guarantee continued industry leadership.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Odd - even staggering, a result of γ - band split

    International Nuclear Information System (INIS)

    Singh, M.; Gupta, D.K.; Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Sharma, Aparna; Varshney, A.K.; Varshney, Mani

    2011-01-01

    The structure of low - lying K = 2+ gamma band in even - even nuclei represents quadrupole vibration breaking axial symmetry in unified collective model of Bohr-Mottelson. In the group theoretical approach of the Interacting boson model (IBM) the band structure can belong to one of the three limiting symmetries of U (6) algebra viz. U (5), SU (3) and O (6), corresponding to the anharmonic vibrator, deformed rotor and γ - unstable respectively

  15. Application of system concept in vibration and noise reduction

    Directory of Open Access Journals (Sweden)

    SHENG Meiping

    2017-08-01

    Full Text Available Although certain vibration and noise control technologies are maturing, such as vibration absorption, vibration isolation, sound absorption and sound insulation, and new methods for specific frequency bands or special environments have been proposed unceasingly, there is still no guarantee that practical effective vibration and noise reduction can be obtained. An important constraint for vibration and noise reduction is the lack of a system concept, and the integrity and relevance of such practical systems as ship structure have not obtained enough attention. We have tried to use the system engineering theory in guiding vibration and noise reduction, and have already achieved certain effects. Based on the system concept, the noise control of a petroleum pipeline production workshop has been completed satisfactorily, and the abnormal noise source identification of an airplane has been accomplished successfully. We want to share our experience and suggestions to promote the popularization of the system engineering theory in vibration and noise control.

  16. Vibrational population distributions in nonequilibrium nozzle expansion flows

    Science.gov (United States)

    Watt, W. S.; Rich, J. W.

    1971-01-01

    Experimental measurements and theoretical calculations of the vibrational population distribution in nonequilibrium nozzle expansion flows of gas mixtures are reported. These studies were directed toward determining whether vibrational energy exchange pumping could lead to laser action on the vibrational bands of a diatomic molecule. Three different types of experiments were conducted. These showed (1) that vibrational energy was preferentially transferred from N2 to CO in supersonic nozzle flows containing these gases; (2) that under some conditions this vibrational energy exchange pumping mechanism created population inversions in the vibrational levels of CO; and (3) that at large expansion ratios the magnitude of these population inversions was sufficient to sustain lasing in the nozzle. A theoretical model was developed to calculate vibrational state population distributions in gas dynamic expansions of a mixture of diatomic gases. Although only isothermal calculations have been completed, these data indicate that population inversions are predicted for conditions similar to those obtained in the nozzle expansion flows.

  17. Multiple refraction switches realized by stretching elastomeric scatterers in sonic crystals

    Directory of Open Access Journals (Sweden)

    Y. Huang

    2015-02-01

    Full Text Available The effect of out-of-plane pre-stretch on the 2D sonic crystal with stretchable elastomeric scatterers is explored. The hyperelastic scatterers are characterized by a compressible neo-Hookean model. The Dirichlet-to-Neumann (DtN map is adopted to obtain the band structure and equi-frequency contours. We focus on the first passband and find that a variety of switching functionalities for refraction behaviors can be realized in selected frequencies under a specific pre-stretch range. These refraction switches enable an active control of wave propagation and are applicable in advanced technologies where switchable and multifunctional sonic crystals are required.

  18. Vibrational Spectroscopy of the CCl[subscript 4] v[subscript 1] Mode: Theoretical Prediction of Isotopic Effects

    Science.gov (United States)

    Gaynor, James D.; Wetterer, Anna M.; Cochran, Rea M.; Valente, Edward J.; Mayer, Steven G.

    2015-01-01

    Raman spectroscopy is a powerful experimental technique, yet it is often missing from the undergraduate physical chemistry laboratory curriculum. Tetrachloromethane (CCl[subscript 4]) is the ideal molecule for an introductory vibrational spectroscopy experiment and the symmetric stretch vibration contains fine structure due to isotopic variations…

  19. Stretch due to Penile Prosthesis Reservoir Migration

    Directory of Open Access Journals (Sweden)

    E. Baten

    2016-03-01

    Full Text Available A 43-year old patient presented to the emergency department with stretch, due to impossible deflation of the penile prosthesis, 4 years after successful implant. A CT-scan showed migration of the reservoir to the left rectus abdominis muscle. Refilling of the reservoir was inhibited by muscular compression, causing stretch. Removal and replacement of the reservoir was performed, after which the prosthesis was well-functioning again. Migration of the penile prosthesis reservoir is extremely rare but can cause several complications, such as stretch.

  20. Vibrations of alkali metal overlayers on metal surfaces

    International Nuclear Information System (INIS)

    Rusina, G G; Eremeev, S V; Borisova, S D; Echenique, P M; Chulkov, E V; Benedek, G

    2008-01-01

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation

  1. Effect of heavy hydrogen isotopes on the vibrational line shape for supercritical water through rotational couplings.

    Science.gov (United States)

    Yoshida, Ken; Matubayasi, Nobuyuki; Uosaki, Yasuhiro; Nakahara, Masaru

    2013-04-07

    The rotational couplings, which determine the infrared spectral line shape in the low-density supercritical water, were analyzed as functions of the density and the temperature by applying molecular dynamics simulation to a flexible water model, SPC∕Fw and by varying the moment of inertia of the water through substitution for the H atom in H2O by heavy hydrogen isotopes. The differences in the frequency and the relative intensity between the sharp center peak and the rotational broad side-bands were analyzed for the O-H, O-D, and O-T stretch spectra. The frequency differences between the sharp center peak and the rotational broad side-bands are linearly correlated with the inverse of the moment of inertia of the isotope-substituted water species. The intensity of the sharp peak is associated with the long-time component of the reorientational time correlation function for the stretching bond vector. At 400 °C, where a substantial amount of hydrogen bonds are dynamically persisting, an intensity decrease in the rotational broad side-bands was observed with increasing density from 0.01 to 0.40 g cm(-3), respectively, corresponding to 0.56 and 22.2 M (=mol dm(-3)), orders of magnitude higher than the ideal gas densities. This arises from the decrease in the correlation time of the angular velocity and the rotational couplings due to an increase in the hydrogen-bonding perturbation. The intensity decrease of the rotational side-bands with increasing density is more significant for the water isotopes with heavier hydrogens. At a high temperature of 1200 °C, the rotational side-bands at 0.01 to 0.05 g cm(-3) were more distinct than those at 400 °C, and even at a medium density of 0.40 g cm(-3) a significant signal broadening due to the rotational couplings was clearly observed because of the accelerated rotational momentum. The vibrational spectrum cannot be decomposed into definite chemical clusters for the thermodynamic and kinetic analysis because of the dynamic

  2. Efficient Vibrational Energy Transfer through Covalent Bond in Indigo Carmine Revealed by Nonlinear IR Spectroscopy.

    Science.gov (United States)

    He, Xuemei; Yu, Pengyun; Zhao, Juan; Wang, Jianping

    2017-10-12

    Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethyl sulfoxide were examined using femtosecond pump-probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-bonded C═O and delocalized C═C stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of the vibrationally excited C═O stretching mode was found to occur through covalent bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less. Vibrational quantum beating was observed in magic-angle pump-probe, anisotropy, and 2D IR cross-peak dynamics, showing an oscillation period of ca. 1010 fs, which corresponds to the energy difference between the C═O and C═C transition frequency (33 cm -1 ). This confirms a resonant vibrational energy transfer happened between the two vibrators. However, a more efficient energy-accepting mode of the excited C═O stretching was believed to be a nearby combination and/or overtone mode that is more tightly connected to the C═O species. On the structural aspect, dynamical-time-dependent 2D IR spectra reveal an insignificant inhomogeneous contribution to time-correlation relaxation for both the C═O and C═C stretching modes, which is in agreement with the generally believed structural rigidity of such conjugated molecules.

  3. Effect of modified hold-relax stretching and static stretching on hamstring muscle flexibility.

    Science.gov (United States)

    Ahmed, Hashim; Iqbal, Amir; Anwer, Shahnawaz; Alghadir, Ahmad

    2015-02-01

    [Purpose] The aim of present study was to compare the effectiveness of modified hold-relax stretching and static stretching in improving the hamstring muscle flexibility. [Subjects and Methods] Forty-five male subjects with hamstring tightness were included in this study. The subjects were randomly placed into three groups: the modified hold-relax stretching, static stretching and control groups. The modified hold-relax stretching group performed 7 seconds of isometric contraction and then relaxed for 5 seconds, and this was repeated five times daily for five consecutive days. The static stretching group received 10 minutes of static stretching with the help of a pulley and weight system for five consecutive days. The control group received only moist heat for 20 minutes for five consecutive days. A baseline reading of passive knee extension (PKE) was taken prior to the intervention; rest measurements were taken immediate post intervention on day 1, day 3, day 5, and after a 1 week follow-up, i.e., at the 12th day. [Results] On comparing the baseline readings of passive knee extension (PKE), there was no difference noted between the three groups. On comparing the posttest readings on day 5 between the 3 groups, a significant difference was noted. However, post hoc analysis revealed an insignificant difference between the modified hold-relax stretching and static stretching groups. There was a significant difference between the static stretching and control groups and between the modified hold-relax stretching and control groups. [Conclusion] The results of this study indicate that both the modified hold-relax stretching technique and static stretching are equally effective, as there was no significant difference in improving the hamstring muscle flexibility between the two groups.

  4. Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

    International Nuclear Information System (INIS)

    Mandal, Aritra; Tokmakoff, Andrei

    2015-01-01

    We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O–H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm −1 . We observe rapid vibrational relaxation processes on 150–250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1–2 ps time scales. Furthermore, the O–H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions

  5. Quantum chemical study of agonist-receptor vibrational interactions for activation of the glutamate receptor.

    Science.gov (United States)

    Kubo, M; Odai, K; Sugimoto, T; Ito, E

    2001-06-01

    To understand the mechanism of activation of a receptor by its agonist, the excitation and relaxation processes of the vibrational states of the receptor should be examined. As a first approach to this problem, we calculated the normal vibrational modes of agonists (glutamate and kainate) and an antagonist (6-cyano-7-nitroquinoxaline-2,3-dione: CNQX) of the glutamate receptor, and then investigated the vibrational interactions between kainate and the binding site of glutamate receptor subunit GluR2 by use of a semiempirical molecular orbital method (MOPAC2000-PM3). We found that two local vibrational modes of kainate, which were also observed in glutamate but not in CNQX, interacted through hydrogen bonds with the vibrational modes of GluR2: (i) the bending vibration of the amine group of kainate, interacting with the stretching vibration of the carboxyl group of Glu705 of GluR2, and (ii) the symmetric stretching vibration of the carboxyl group of kainate, interacting with the bending vibration of the guanidinium group of Arg485. We also found collective modes with low frequency at the binding site of GluR2 in the kainate-bound state. The vibrational energy supplied by an agonist may flow from the high-frequency local modes to the low-frequency collective modes in a receptor, resulting in receptor activation.

  6. Mixed quantum/classical approach to OH-stretch inelastic incoherent neutron scattering spectroscopy for ambient and supercooled liquid water and ice Ih

    International Nuclear Information System (INIS)

    Shi, L.; Skinner, J. L.

    2015-01-01

    OH-stretch inelastic incoherent neutron scattering (IINS) has been measured to determine the vibrational density of states (VDOS) in the OH-stretch region for liquid water, supercooled water, and ice Ih, providing complementary information to IR and Raman spectroscopies about hydrogen bonding in these phases. In this work, we extend the combined electronic-structure/molecular-dynamics (ES/MD) method, originally developed by Skinner and co-workers to simulate OH-stretch IR and Raman spectra, to the calculation of IINS spectra with small k values. The agreement between theory and experiment in the limit k → 0 is reasonable, further validating the reliability of the ES/MD method in simulating OH-stretch spectroscopy in condensed phases. The connections and differences between IINS and IR spectra are analyzed to illustrate the advantages of IINS over IR in estimating the OH-stretch VDOS

  7. Investing in a Large Stretch Press

    Science.gov (United States)

    Choate, M.; Nealson, W.; Jay, G.; Buss, W.

    1986-01-01

    Press for forming large aluminum parts from plates provides substantial economies. Study assessed advantages and disadvantages of investing in large stretch-forming press, and also developed procurement specification for press.

  8. Excluded Volume Effects in Gene Stretching

    OpenAIRE

    Lam, Pui-Man

    2002-01-01

    We investigate the effects excluded volume on the stretching of a single DNA in solution. We find that for small force F, the extension h is not linear in F but proportion to F^{\\chi}, with \\chi=(1-\

  9. Phononic band gap structures as optimal designs

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Sigmund, Ole

    2003-01-01

    In this paper we use topology optimization to design phononic band gap structures. We consider 2D structures subjected to periodic loading and obtain the distribution of two materials with high contrast in material properties that gives the minimal vibrational response of the structure. Both in...

  10. Vibration and DFT analysis of 2-methyl-3-nitrophenyl isocyanate and 4-methyl-2-nitrophenyl isocyanate

    Science.gov (United States)

    Tonannavar, J.; Prasannakumar, Sushanti; Savanur, J.; Yenagi, Jayashree

    2012-09-01

    Vibrational spectra of 2-methyl-3-nitrophenyl isocyanate and 4-methyl-2-nitrophenyl isocyanate, in the spectral region 4000-100 cm-1, have been measured and assigned. Conformational and harmonic frequency analyses have been performed at B3LYP/6-311G∗ level of calculations. The two stable conformers, cis and trans, have been computed for each of the molecules. It has been determined that the trans conformer has lower energy than the cis by 3.954 kJ/mol for 2-methyl-3-nitrophenyl isocyanate; whereas the cis conformer has lower energy than the trans by 10.230 kJ/mol for 4-methyl-2-nitrophenyl isocyanate. The vibration structure of 2-methyl-3-nitrophenyl isocyanate conforms to the combined behavior of its both conformers from which the deviation is shown by the structure of 4-methyl-2-nitrophenyl isocyanate which follows only the trans conformer. The occurrence of symmetric mode of the methyl group at higher frequency near 2944-20 cm-1 is attributed to the phenyl ring strain caused by the substituents. As for the other stretching and bending modes, mutually exclusive pattern appears to work for the molecules: The nitro group's non-coplanarity with the phenyl ring is more evident in 4-methyl-2-nitrophenyl isocyanate where the asymmetric mode was assigned to the band at 1569 cm-1, whereas the symmetric mode at lower frequency 1339 cm-1. Occasional doublet appearance of the strong asymmetric absorption near 2282 cm-1 due to isocyanate moiety has been observed in the present study and is assumed to arise from the torsional vibration motion of the moiety rendered by the small energy gap between the conformers of 2-methyl-3-nitrophenyl isocyanate.

  11. Study of polymorphism in imatinib mesylate: A quantum chemical approach using electronic and vibrational spectra

    Science.gov (United States)

    Srivastava, Anubha; Joshi, B. D.; Tandon, Poonam; Ayala, A. P.; Bansal, A. K.; Grillo, Damián

    2013-02-01

    Imatinib mesylate, 4-(4-methyl-piperazin-1-ylmethyl)-N-u[4-methyl-3-(4-pyridin-3-yl)pyrimidine-2-ylamino)phenyl]benzamide methanesulfonate is a therapeutic drug that is approved for the treatment of chronic myelogeneous leukemia (CML) and gastrointestinal stromal tumors (GIST). It is known that imatinib mesylate exists in two polymorphic forms α and β. However, β-form is more stable than the α-form. In this work, we present a detailed vibrational spectroscopic investigation of β-form by using FT-IR and FT-Raman spectra. These data are supported by quantum mechanical calculations using DFT employing 6-311G(d,p) basis set, which allow us to characterize completely the vibrational spectra of this compound. The FT-IR spectrum of α-form has also been discussed. The importance of hydrogen-bond formation in the molecular packing arrangements of both forms has been examined with the vibrational shifts observed due to polymorphic changes. The red shift of the NH stretching bands in the infrared spectrum from the computed wavenumber indicates the weakening of the NH bond. The UV-vis spectroscopic studies along with the HOMO-LUMO analysis of both polymorphs (α and β) were performed and their chemical activity has been discussed. The TD-DFT method was used to calculate the electronic absorption spectra in the gas phase as well as in the solvent environment using IEF-PCM model and 6-31G basis set. Finally, the results obtained complements to the experimental findings.

  12. DNA stretching on functionalized gold surfaces.

    OpenAIRE

    Zimmermann, R M; Cox, E C

    1994-01-01

    We describe a method for anchoring bacteriophage lambda DNA by one end to gold by Au-biotin-streptavidin-biotin-DNA bonds. DNA anchored to a microfabricated Au line could be aligned and stretched in flow and electric fields. The anchor was shown to resist a force of at least 11 pN, a linkage strong enough to allow DNA molecules of chromosome size to be stretched and aligned.

  13. Comparisons of the Structure of Water at Neat Oil/Water and Air/Water Interfaces as Determined by Vibrational Sum Frequency Generation

    National Research Council Canada - National Science Library

    Gragson, D

    1997-01-01

    We have employed vibrational sum frequency generation (VSFG) to investigate the structure of water at neat oil/water and air/water interfaces through the OH stretching modes of the interfacial water molecules...

  14. Molecular and vibrational structure of diphenylether and its 4,4' -dibromo derivative. Infrared linear dichroism spectroscopy and density functional theory calculations

    DEFF Research Database (Denmark)

    Eriksen, Troels K; Karlsen, Eva; Spanget-Larsen, Jens

    2015-01-01

    The title compounds were investigated by means of Linear Dichroism (LD) IR spectroscopy on samples partially aligned in uniaxially stretched low-density polyethylene and by density functional theory calculations. Satisfactory overall agreement between observed and calculated vibrational wavenumbers...

  15. Experimental Investigation on Cavitating Flow Induced Vibration Characteristics of a Low Specific Speed Centrifugal Pump

    OpenAIRE

    Bo Gao; Pengming Guo; Ning Zhang; Zhong Li; Minguan Yang

    2017-01-01

    Cavitating flow developing in the blade channels is detrimental to the stable operation of centrifugal pumps, so it is essential to detect cavitation and avoid the unexpected results. The present paper concentrates on cavitation induced vibration characteristics, and special attention is laid on vibration energy in low frequency band, 10–500 Hz. The correlation between cavitating evolution and the corresponding vibration energy in 10–500 Hz frequency band is discussed through visualization an...

  16. Comparison of two stretching methods and optimization of stretching protocol for the piriformis muscle.

    Science.gov (United States)

    Gulledge, Brett M; Marcellin-Little, Denis J; Levine, David; Tillman, Larry; Harrysson, Ola L A; Osborne, Jason A; Baxter, Blaise

    2014-02-01

    Piriformis syndrome is an uncommon diagnosis for a non-discogenic form of sciatica whose treatment has traditionally focused on stretching the piriformis muscle (PiM). Conventional stretches include hip flexion, adduction, and external rotation. Using three-dimensional modeling, we quantified the amount of (PiM) elongation resulting from two conventional stretches and we investigated by use of a computational model alternate stretching protocols that would optimize PiM stretching. Seven subjects underwent three CT scans: one supine, one with hip flexion, adduction, then external rotation (ADD stretch), and one with hip flexion, external rotation, then adduction (ExR stretch). Three-dimensional bone models were constructed from the CT scans. PiM elongation during these stretches, femoral neck inclination, femoral head anteversion, and trochanteric anteversion were measured. A computer program was developed to map PiM length over a range of hip joint positions and was validated against the measured scans. ExR and ADD stretches elongated the PiM similarly by approximately 12%. Femoral head and greater trochanter anteversion influenced PiM elongation. Placing the hip joints in 115° of hip flexion, 40° of external rotation and 25° of adduction or 120° of hip flexion, 50° of external rotation and 30° of adduction increased PiM elongation by 30-40% compared to conventional stretches (15.1 and 15.3% increases in PiM muscle length, respectively). ExR and ADD stretches elongate the PiM similarly and therefore may have similar clinical effectiveness. The optimized stretches led to larger increases in PiM length and may be more easily performed by some patients due to increased hip flexion. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

  17. Effects of proprioceptive neuromuscular facilitation stretching and static stretching on maximal voluntary contraction.

    Science.gov (United States)

    Miyahara, Yutetsu; Naito, Hisashi; Ogura, Yuji; Katamoto, Shizuo; Aoki, Junichiro

    2013-01-01

    This study was undertaken to investigate and compare the effects of proprioceptive neuromuscular facilitation (PNF) stretching and static stretching on maximal voluntary contraction (MVC). Thirteen male university students (age, 20 ± 1 years; height, 172.2 ± 4.6 cm; weight, 68.4 ± 6.7 kg; mean ± SD) completed 3 different conditions on 3 nonconsecutive days in randomized order: static stretching (SS), PNF stretching (PNF), and no stretching (control, CON). Each condition consisted of a 5-minute rest accompanied by one of the following activities: (a) control, (b) SS, or (c) PNF stretching. The hip flexion range of motion (ROM) was evaluated immediately before and after the activity. The MVC of knee flexion was then measured. Surface electromyography was recorded from the biceps femoris and vastus lateralis muscles during MVC tests and stretching. Although increases in ROM were significantly greater after PNF than after SS (p < 0.01), the decreases in MVC were similar between the 2 treatments. These results suggest that, although PNF stretching increases ROM more than SS, PNF stretching and SS is detrimental to isometric maximal strength.

  18. On the intermolecular vibrational coupling, hydrogen bonding, and librational freedom of water in the hydration shell of mono- and bivalent anions.

    Science.gov (United States)

    Ahmed, Mohammed; Namboodiri, V; Singh, Ajay K; Mondal, Jahur A

    2014-10-28

    The hydration energy of an ion largely resides within the first few layers of water molecules in its hydration shell. Hence, it is important to understand the transformation of water properties, such as hydrogen-bonding, intermolecular vibrational coupling, and librational freedom in the hydration shell of ions. We investigated these properties in the hydration shell of mono- (Cl(-) and I(-)) and bivalent (SO4(2-) and CO3(2-)) anions by using Raman multivariate curve resolution (Raman-MCR) spectroscopy in the OH stretch, HOH bend, and [bend+librational] combination bands of water. Raman-MCR of aqueous Na-salt (NaCl, NaI, Na2SO4, and Na2CO3) solutions provides ion-correlated spectra (IC-spectrum) which predominantly bear the vibrational characteristics of water in the hydration shell of respective anions. Comparison of these IC-spectra with the Raman spectrum of bulk water in different spectral regions reveals that the water is vibrationally decoupled with its neighbors in the hydration shell. Hydrogen-bond strength and librational freedom also vary with the nature of anion: hydrogen-bond strength, for example, decreases as CO3(2-) > SO4(2-) > bulk water ≈ Cl(-) > I(-); and the librational freedom increases as CO3(2-) ≈ SO4(2-) water water in the hydration shell of anions.

  19. Large shift and small broadening of Br2 valence band upon dimer formation with H2O: an ab initio study.

    Science.gov (United States)

    Franklin-Mergarejo, Ricardo; Rubayo-Soneira, Jesus; Halberstadt, Nadine; Ayed, Tahra; Bernal-Uruchurtu, Margarita I; Hernández-Lamoneda, Ramón; Janda, Kenneth C

    2011-06-16

    Valence electronic excitation spectra are calculated for the H(2)O···Br(2) complex using highly correlated ab initio potentials for both the ground and the valence electronic excited states and a 2-D approximation for vibrational motion. Due to the strong interaction between the O-Br and the Br-Br stretching motions, inclusion of these vibrations is the minimum necessary for the spectrum calculation. A basis set calculation is performed to determine the vibrational wave functions for the ground electronic state and a wave packet simulation is conducted for the nuclear dynamics on the excited state surfaces. The effects of both the spin-orbit interaction and temperature on the spectra are explored. The interaction of Br(2) with a single water molecule induces nearly as large a shift in the spectrum as is observed for an aqueous solution. In contrast, complex formation has a remarkably small effect on the T = 0 K width of the valence bands due to the fast dissociation of the dihalogen bond upon excitation. We therefore conclude that the widths of the spectra in aqueous solution are mostly due to inhomogeneous broadening. © 2011 American Chemical Society

  20. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

  1. Comparison of active stretching technique and static stretching technique on hamstring flexibility.

    Science.gov (United States)

    Meroni, Roberto; Cerri, Cesare Giuseppe; Lanzarini, Carlo; Barindelli, Guido; Morte, Giancesare Della; Gessaga, Viviana; Cesana, Gian Carlo; De Vito, Giovanni

    2010-01-01

    To compare a passive and an active stretching technique to determine which one would produce and maintain the greatest gain in hamstring flexibility. To determine whether a passive or an active stretching technique results in a greater increase in hamstring flexibility and to compare whether the gains are maintained. Randomized controlled trial. Institutional. Sixty-five volunteer healthy subjects completed the enrollment questionnaire, 33 completed the required 75% of the treatment after 6 weeks, and 22 were assessed 4 weeks after the training interruption. A 6-week stretching program with subjects divided into 2 groups with group 1 performing active stretching exercises and group 2 performing passive stretching exercises. Range of motion (ROM) was measured after 3 and 6 weeks of training and again 4 weeks after the cessation of training and compared with the initial measurement. After 3 weeks of training, the mean gain in group 1 (active stretching) on performing the active knee extension range of motion (AKER) test was 5.7 degrees, whereas the mean gain in group 2 (passive stretching) was 3 degrees (P = .015). After 6 weeks of training, the mean gain in group 1 was 8.7 degrees , whereas the mean gain in group 2 was 5.3 degrees (P = .006). Twenty-two subjects were reassessed 4 weeks after the cessation of the training with the maintained gain of ROM in group 1 being 6.3 degrees , whereas the maintained gain in group 2 was 0.1 degrees (P = .003). Active stretching produced the greater gain in the AKER test, and the gain was almost completely maintained 4 weeks after the end of the training, which was not seen with the passive stretching group. Active stretching was more time efficient compared with the static stretching and needed a lower compliance to produce effects on flexibility.

  2. Distributed Absorber for Noise and Vibration Control

    Directory of Open Access Journals (Sweden)

    Michel Azoulay

    2011-01-01

    Full Text Available An approach to a wide-band frequency passive vibration attenuation is introduced in this paper. This aims to suppress noise and vibration of extended multimode objects like plates, panels and shells. The absorber is arranged in the form of a single-layer assembly of small inertial bodies (balls being distributed and moulded within the light visco-elastic media (e.g. silicone resin. The absorber as a whole is embedded into object face covering the critical patches of the system surface. For the purpose of characterization, the authors introduced the complex frequency response function relating the volume velocity produced by the vibrating object surface (response stimulated by a point-wise force (stimulus applied to a particular point. The simulation and optimization of the main frequency characteristics has been performed using a full scale 3-dimensional Finite Element model. These revealed some new dynamic features of absorber's structures, which can contribute to vibration attenuation. A full-scale physical experimentation with synthesised absorber's structures confirmed the main results of simulation and has shown significant noise reduction over a staggering 0–20 kHz frequency band. This was achieved with a negligible weight and volume penalty due to the addition of the absorber. The results can find multiple applications in noise and vibration control of different structures. Some examples of such applications are presented.

  3. How to determine local stretching and tension in a flow-stretched DNA molecule

    DEFF Research Database (Denmark)

    Pedersen, Jonas Nyvold; Marie, Rodolphe; Kristensen, Anders

    2016-01-01

    We determine the nonuniform stretching of and tension in amega base pairs-long fragment of deoxyribonucleic acid (DNA) that is flow stretched in a nanofluidic chip. We use no markers, do not know the contour length of the DNA, and do not have the full DNA molecule inside our field of view. Instead...

  4. The dynamics of a shear band

    Science.gov (United States)

    Giarola, Diana; Capuani, Domenico; Bigoni, Davide

    2018-03-01

    A shear band of finite length, formed inside a ductile material at a certain stage of a continued homogeneous strain, provides a dynamic perturbation to an incident wave field, which strongly influences the dynamics of the material and affects its path to failure. The investigation of this perturbation is presented for a ductile metal, with reference to the incremental mechanics of a material obeying the J2-deformation theory of plasticity (a special form of prestressed, elastic, anisotropic, and incompressible solid). The treatment originates from the derivation of integral representations relating the incremental mechanical fields at every point of the medium to the incremental displacement jump across the shear band faces, generated by an impinging wave. The boundary integral equations (under the plane strain assumption) are numerically approached through a collocation technique, which keeps into account the singularity at the shear band tips and permits the analysis of an incident wave impinging a shear band. It is shown that the presence of the shear band induces a resonance, visible in the incremental displacement field and in the stress intensity factor at the shear band tips, which promotes shear band growth. Moreover, the waves scattered by the shear band are shown to generate a fine texture of vibrations, parallel to the shear band line and propagating at a long distance from it, but leaving a sort of conical shadow zone, which emanates from the tips of the shear band.

  5. Nonlinear vibration of an axially loaded beam carrying rigid bodies

    Directory of Open Access Journals (Sweden)

    O. Barry

    2016-12-01

    Full Text Available This paper investigates the nonlinear vibration due to mid-plane stretching of an axially loaded simply supported beam carrying multiple rigid masses. Explicit expressions and closed form solutions of both linear and nonlinear analysis of the present vibration problem are presented for the first time. The validity of the analytical model is demonstrated using finite element analysis and via comparison with the result in the literature. Parametric studies are conducted to examine how the nonlinear frequency and frequency response curve are affected by tension, rotational inertia, and number of intermediate rigid bodies.

  6. Vibrations and Stability

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    About this textbook An ideal text for students that ties together classical and modern topics of advanced vibration analysis in an interesting and lucid manner. It provides students with a background in elementary vibrations with the tools necessary for understanding and analyzing more complex...... dynamical phenomena that can be encountered in engineering and scientific practice. It progresses steadily from linear vibration theory over various levels of nonlinearity to bifurcation analysis, global dynamics and chaotic vibrations. It trains the student to analyze simple models, recognize nonlinear...... and physics. This edition includes a new chapter on the useful effects of fast vibrations and many new exercise problems. Written for: Students in mechanical or structural engineering. Keywords: Nonlinear Vibrations, Bifurcations, Chaotic Vibrations, Vibrations and Stability....

  7. Human response to vibration

    National Research Council Canada - National Science Library

    Mansfield, Neil J

    2005-01-01

    .... Vibration measurements and standards are also addressed. This book meets the needs of those requiring knowledge of human response to vibration in order to make practical improvements to physical working environments...

  8. Vibrations and Stability

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    dynamical phenomena that can be encountered in engineering and scientific practice. It progresses steadily from linear vibration theory over various levels of nonlinearity to bifurcation analysis, global dynamics and chaotic vibrations. It trains the student to analyze simple models, recognize nonlinear...... and physics. This edition includes a new chapter on the useful effects of fast vibrations and many new exercise problems. Written for: Students in mechanical or structural engineering. Keywords: Nonlinear Vibrations, Bifurcations, Chaotic Vibrations, Vibrations and Stability.......About this textbook An ideal text for students that ties together classical and modern topics of advanced vibration analysis in an interesting and lucid manner. It provides students with a background in elementary vibrations with the tools necessary for understanding and analyzing more complex...

  9. CURRENT CONCEPTS IN MUSCLE STRETCHING FOR EXERCISE AND REHABILITATION

    Science.gov (United States)

    2012-01-01

    Stretching is a common activity used by athletes, older adults, rehabilitation patients, and anyone participating in a fitness program. While the benefits of stretching are known, controversy remains about the best type of stretching for a particular goal or outcome. The purpose of this clinical commentary is to discuss the current concepts of muscle stretching interventions and summarize the evidence related to stretching as used in both exercise and rehabilitation. PMID:22319684

  10. CURRENT CONCEPTS IN MUSCLE STRETCHING FOR EXERCISE AND REHABILITATION

    OpenAIRE

    Page, Phil

    2012-01-01

    Stretching is a common activity used by athletes, older adults, rehabilitation patients, and anyone participating in a fitness program. While the benefits of stretching are known, controversy remains about the best type of stretching for a particular goal or outcome. The purpose of this clinical commentary is to discuss the current concepts of muscle stretching interventions and summarize the evidence related to stretching as used in both exercise and rehabilitation.

  11. Molecular and vibrational structure of 2,2'-dihydroxybenzophenone

    DEFF Research Database (Denmark)

    Birklund Andersen, Kristine; Langgård, M.; Spanget-Larsen, Jens

    1999-01-01

    2,2'-dihydroxybenzophenone (DHBP) contains similar bifold intramolecular H-bonding as the psoriatic drug anthralin, but because of steric interference the phenolic rings are twisted in a propeller-like manner, resulting in a molecular structure of C2 symmetry. In contrast to the case of C2v...... anthralin, the description of the vibrational structure of the compound is thus complicated by the circumstance that moment directions for transitions polarized perpendicular to the C2 axis (z) are not uniquely determined by symmetry, but can take any direction in the xy plane. The molecular vibrations...... of DHBP were investigated by IR polarization spectroscopy on samples aligned in stretched polyethylene. The observed Linear Dichroic (LD) absorbance curves, corresponding to absorbance measured with the electric vector of the sample beam parallel (U) and perpendicular (V) to the stretching direction, were...

  12. Tunable Passive Vibration Suppressor

    Science.gov (United States)

    Boechler, Nicholas (Inventor); Dillon, Robert Peter (Inventor); Daraio, Chiara (Inventor); Davis, Gregory L. (Inventor); Shapiro, Andrew A. (Inventor); Borgonia, John Paul C. (Inventor); Kahn, Daniel Louis (Inventor)

    2016-01-01

    An apparatus and method for vibration suppression using a granular particle chain. The granular particle chain is statically compressed and the end particles of the chain are attached to a payload and vibration source. The properties of the granular particles along with the amount of static compression are chosen to provide desired filtering of vibrations.

  13. Vibration of plates

    CERN Document Server

    Chakraverty, Snehashish

    2008-01-01

    Plates are integral parts of most engineering structures and their vibration analysis is required for safe design. This work provides a comprehensive introduction to vibration theory and analysis of two-dimensional plates. It offers information on vibration problems along with a discussion of various plate geometries and boundary conditions.

  14. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.

  15. Octupole vibration in the superdeformed {sup 196}Pb nucleus; Vibration octupolaire dans le noyau superdeforme {sup 196}Pb

    Energy Technology Data Exchange (ETDEWEB)

    Bouneau, S.; Azaiez, F.; Duprat, J. [Experimental Research Division, Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)] [and others

    1999-11-01

    The study of the superdeformed (SD) {sup 196}Pb nucleus has been revisited using the EUROGAM phase 2 spectrometer. All the three observed excited SD bands were found to decay to the Yrast SD band through, presumably, E1 transitions, allowing relative spin and excited energy assignments. Comparisons with calculation using the random phase approximation suggests that all three excited bands can be interpreted as octupole vibrational structures. (authors) 5 refs., 1 fig.

  16. Summary of the stretching tectonics research

    International Nuclear Information System (INIS)

    Yu Dagan

    1994-01-01

    The rise of stretching tectonics is established on the basis of recent structural geology theory, the establishment of metamorphic nucleus complex structural model on one hand plays an important promoting art to the development of stretching structure, on the other hand, it needs constant supplement and perfection in practice. Metamorphic nucleus complex is the carrier of comparatively deep geological information in vertical section of the crust and has wide distribution in the era of south China. Evidently, it can be taken as the 'key' to understanding the deep and studying the basement, Strengthening the study will play the important promoting role to the deep prospecting. The study of stretching tectonics is not only limited within the range of structure and metamorphism, but combine with the studies of sedimentation, magmatism, metamorphism and mineralization, thus form a new field of tectonic geology of self-developing system

  17. Optofluidic time-stretch microscopy: recent advances

    Science.gov (United States)

    Lei, Cheng; Nitta, Nao; Ozeki, Yasuyuki; Goda, Keisuke

    2018-04-01

    Flow cytometry is an indispensable method for valuable applications in numerous fields such as immunology, pathology, pharmacology, molecular biology, and marine biology. Optofluidic time-stretch microscopy is superior to conventional flow cytometry methods for its capability to acquire high-quality images of single cells at a high-throughput exceeding 10,000 cells per second. This makes it possible to extract copious information from cellular images for accurate cell detection and analysis with the assistance of machine learning. Optofluidic time-stretch microscopy has proven its effectivity in various applications, including microalga-based biofuel production, evaluation of thrombotic disorders, as well as drug screening and discovery. In this review, we discuss the principles and recent advances of optofluidic time-stretch microscopy.

  18. Optofluidic time-stretch quantitative phase microscopy.

    Science.gov (United States)

    Guo, Baoshan; Lei, Cheng; Wu, Yi; Kobayashi, Hirofumi; Ito, Takuro; Yalikun, Yaxiaer; Lee, Sangwook; Isozaki, Akihiro; Li, Ming; Jiang, Yiyue; Yasumoto, Atsushi; Di Carlo, Dino; Tanaka, Yo; Yatomi, Yutaka; Ozeki, Yasuyuki; Goda, Keisuke

    2018-03-01

    Innovations in optical microscopy have opened new windows onto scientific research, industrial quality control, and medical practice over the last few decades. One of such innovations is optofluidic time-stretch quantitative phase microscopy - an emerging method for high-throughput quantitative phase imaging that builds on the interference between temporally stretched signal and reference pulses by using dispersive properties of light in both spatial and temporal domains in an interferometric configuration on a microfluidic platform. It achieves the continuous acquisition of both intensity and phase images with a high throughput of more than 10,000 particles or cells per second by overcoming speed limitations that exist in conventional quantitative phase imaging methods. Applications enabled by such capabilities are versatile and include characterization of cancer cells and microalgal cultures. In this paper, we review the principles and applications of optofluidic time-stretch quantitative phase microscopy and discuss its future perspective. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Bias of purine stretches in sequenced chromosomes

    DEFF Research Database (Denmark)

    Ussery, David; Soumpasis, Dikeos Mario; Brunak, Søren

    2002-01-01

    We examined more than 700 DNA sequences (full length chromosomes and plasmids) for stretches of purines (R) or pyrimidines (Y) and alternating YR stretches; such regions will likely adopt structures which are different from the canonical B-form. Since one turn of the DNA helix is roughly 10 bp, we...... measured the fraction of each genome which contains purine (or pyrimidine) tracts of lengths of 10 by or longer (hereafter referred to as 'purine tracts'), as well as stretches of alternating pyrimidines/purine ('pyr/pur tracts') of the same length. Using this criteria, a random sequence would be expected...... to contain 1.0% of purine tracts and also 1.0% of the alternating pyr/pur tracts. In the vast majority of cases, there are more purine tracts than would be expected from a random sequence, with an average of 3.5%, significantly larger than the expectation value. The fraction of the chromosomes containing pyr...

  20. Bias of purine stretches in sequenced chromosomes

    DEFF Research Database (Denmark)

    Ussery, David; Soumpasis, Dikeos Mario; Brunak, Søren

    2002-01-01

    We examined more than 700 DNA sequences (full length chromosomes and plasmids) for stretches of purines (R) or pyrimidines (Y) and alternating YR stretches; such regions will likely adopt structures which are different from the canonical B-form. Since one turn of the DNA helix is roughly 10 bp, we...... to contain 1.0% of purine tracts and also 1.0% of the alternating pyr/pur tracts. In the vast majority of cases, there are more purine tracts than would be expected from a random sequence, with an average of 3.5%, significantly larger than the expectation value. The fraction of the chromosomes containing pyr......, in eukaryotes there is an abundance of long stretches of purines or alternating purine/pyrimidine tracts, which cannot be explained in this way; these sequences are likely to play an important role in eukaryotic chromosome organisation....

  1. Anisotropic dewetting on stretched elastomeric substrates.

    Science.gov (United States)

    Qiao, L; He, L H

    2008-08-01

    We study the instability of a very thin liquid film resting on a uniformly stretched soft elastomeric substrate driven by van der Waals forces. A linear stability analysis shows that the critical fluctuation wavelength in the tensile direction is larger than those in the other directions. The magnitudes of the critical wavelengths are adjustable in the sense that they depend on the principal stretch of the substrate. For example, when the principal stretch of the substrate varies from 1.0 (unstretched) to 3.0, the range of the critical wavelength in the tensile direction increases by 7.0% while that normal to the tensile direction decreases by 8.7%. Therefore, the phenomenon may find potential applications in creating tunable topographically patterned surfaces with nano- to microscale features.

  2. Hydrogen bond dynamics and vibrational spectral diffusion in ...

    Indian Academy of Sciences (India)

    For example, Chapados and cowork- ers10 carried out Fourier transform infrared attenuated total reflectance spectroscopic studies of acetone–water mixtures. These authors found that the OH stretch band is blue shifted as acetone is added to water. Recently,. Bakker and coworkers16 looked at the dynamical prop-.

  3. Electrostatics determine vibrational frequency shifts in hydrogen bonded complexes.

    Science.gov (United States)

    Dey, Arghya; Mondal, Sohidul Islam; Sen, Saumik; Ghosh, Debashree; Patwari, G Naresh

    2014-12-14

    The red-shifts in the acetylenic C-H stretching vibration of C-H∙∙∙X (X = O, N) hydrogen-bonded complexes increase with an increase in the basicity of the Lewis base. Analysis of various components of stabilization energy suggests that the observed red-shifts are correlated with the electrostatic component of the stabilization energy, while the dispersion modulates the stabilization energy.

  4. Dynamics of the OH stretching mode in crystalline Ba(ClO4)2.3H2O

    Science.gov (United States)

    Hutzler, Daniel; Brunner, Christian; Petkov, Petko St.; Heine, Thomas; Fischer, Sighart F.; Riedle, Eberhard; Kienberger, Reinhard; Iglev, Hristo

    2018-02-01

    The vibrational dynamics of the OH stretching mode in Ba(ClO4)2 trihydrate are investigated by means of femtosecond infrared spectroscopy. The sample offers plane cyclic water trimers in the solid phase that feature virtually no hydrogen bond interaction between the water molecules. Selective excitation of the symmetric and asymmetric stretching leads to fast population redistribution, while simultaneous excitation yields quantum beats, which are monitored via a combination tone that dominates the overtone spectrum. The combination of steady-state and time-resolved spectroscopy with quantum chemical simulations and general theoretical considerations gives indication of various aspects of symmetry breakage. The system shows a joint population lifetime of 8 ps and a long-lived coherence between symmetric and asymmetric stretching, which decays with a time constant of 0.6 ps.

  5. Flow of nanofluid by nonlinear stretching velocity

    Science.gov (United States)

    Hayat, Tasawar; Rashid, Madiha; Alsaedi, Ahmed; Ahmad, Bashir

    2018-03-01

    Main objective in this article is to model and analyze the nanofluid flow induced by curved surface with nonlinear stretching velocity. Nanofluid comprises water and silver. Governing problem is solved by using homotopy analysis method (HAM). Induced magnetic field for low magnetic Reynolds number is not entertained. Development of convergent series solutions for velocity and skin friction coefficient is successfully made. Pressure in the boundary layer flow by curved stretching surface cannot be ignored. It is found that magnitude of power-law index parameter increases for pressure distibutions. Magnitude of radius of curvature reduces for pressure field while opposite trend can be observed for velocity.

  6. Lattice stretching bistability and dynamic heterogeneity

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Savin, A. V.; Zolotaryuk, A. V.

    2012-01-01

    A simple one-dimensional lattice model is suggested to describe the experimentally observed plateau in force-stretching diagrams for some macromolecules. This chain model involves the nearest-neighbor interaction of a Morse-like potential (required to have a saturation branch) and a harmonic second......-neighbor coupling. Under an external stretching applied to the chain ends, the intersite Morse-like potential results in the appearance of a double-well potential within each chain monomer, whereas the interaction between the second neighbors provides a homogeneous bistable (degenerate) ground state, at least...

  7. Stretching and folding mechanism in foams

    Energy Technology Data Exchange (ETDEWEB)

    Tufaile, Alberto [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)], E-mail: tufaile@usp.br; Pedrosa Biscaia Tufaile, Adriana [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)

    2008-10-13

    We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board.

  8. Band structures in fractal grading porous phononic crystals

    Science.gov (United States)

    Wang, Kai; Liu, Ying; Liang, Tianshu; Wang, Bin

    2018-05-01

    In this paper, a new grading porous structure is introduced based on a Sierpinski triangle routine, and wave propagation in this fractal grading porous phononic crystal is investigated. The influences of fractal hierarchy and porosity on the band structures in fractal graidng porous phononic crystals are clarified. Vibration modes of unit cell at absolute band gap edges are given to manifest formation mechanism of absolute band gaps. The results show that absolute band gaps are easy to form in fractal structures comparatively to the normal ones with the same porosity. Structures with higher fractal hierarchies benefit multiple wider absolute band gaps. This work provides useful guidance in design of fractal porous phononic crystals.

  9. Frequency weightings of hand-transmitted vibration for predicting vibration-induced white finger.

    Science.gov (United States)

    Bovenzi, Massimo; Pinto, Iole; Picciolo, Francesco; Mauro, Marcella; Ronchese, Federico

    2011-05-01

    The aim of this study was to investigate the performance of four frequency weightings for hand-transmitted vibration to predict the incidence of vibration-induced white finger (VWF). In a longitudinal study of vibration-exposed forestry and stone workers (N=206), the incidence of VWF was related to measures of vibration exposure expressed in terms of 8-hour frequency-weighted energy-equivalent root-mean-square (rms) acceleration magnitude [A(8)] and years of follow-up. To calculate A(8), the rms acceleration magnitudes of vibration were weighted by means of four frequency weightings: (i) W(h) (the frequency weighting specified in ISO 5349-1:2001); (ii) W(h-bl) (the band-limiting component of W(h)); (iii) W(hf) (a frequency weighting based on finger vibration power absorption); and (iv) W(hT) (a frequency weighting based on a Japanese study of VWF prevalence). The relations of VWF to alternative measures of vibration exposure were assessed by the generalized estimating equations (GEE) method to account for the within-subject dependency of the observations over time. Data analysis with a GEE logistic model and a measure of statistical fit suggested that calculating A(8) by weighting the tool rms accelerations with W(h-bl)gave better predictions of the cumulative incidence of VWF than the other alternative measures of daily vibration exposure. Values of A(8) derived from the currently recommended ISO frequency weighting Wh produced poorer predictions of the incidence of VWF than those obtained with frequency weightings W(hf)or W(hT). This prospective cohort study suggests that measures of daily vibration exposure which give relatively more weight to intermediate and high frequency vibration are more appropriate for assessing the probability of VWF.

  10. Immediate effects of quantified hamstring stretching: hold-relax proprioceptive neuromuscular facilitation versus static stretching.

    Science.gov (United States)

    Puentedura, Emilio J; Huijbregts, Peter A; Celeste, Shelley; Edwards, Dale; In, Alastair; Landers, Merrill R; Fernandez-de-Las-Penas, Cesar

    2011-08-01

    To compare the immediate effects of a hold-relax proprioceptive neuromuscular facilitation stretching (HR-PNF) versus static stretch (SS) on hamstring flexibility in healthy, asymptomatic subjects. Thirty subjects (13 female; mean age 25.7 ± 3.0, range 22-37) without excessive hamstring muscle flexibility were randomly assigned to one of two stretch groups: HR-PNF or SS. The left leg was treated as a control and did not receive any intervention. The right leg was measured for ROM pre- and post-stretch interventions, with subjects receiving randomly assigned interventions one week apart. Data were analyzed with a 3 (intervention: HR-PNF, SS, control) × 2 (time: pre and post) factorial ANOVA with repeated measures and appropriate post-hoc analyses. A significant interaction was observed between intervention and time for hamstring extensibility, F(2,58) = 25.229, p < .0005. Main effect of intervention for the tested leg was not significant, p = .782 indicating that there was no difference between the two stretch conditions. However, main effect for time was significant (p < .0005), suggesting that hamstring extensibility (for both stretching conditions) after intervention was greater than before. No significant differences were found when comparing the effectiveness of HR-PNF and SS techniques. Both stretching methods resulted in significant immediate increases in hamstring length. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Anti-vibration gloves?

    Science.gov (United States)

    Hewitt, Sue; Dong, Ren G; Welcome, Daniel E; McDowell, Thomas W

    2015-03-01

    For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered. © Crown copyright 2014.

  12. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  13. Realistic searches on stretched exponential networks

    Indian Academy of Sciences (India)

    Vol. 71, No. 2. — journal of. August 2008 physics pp. 313–317. Realistic searches on stretched exponential networks. PARONGAMA SEN. Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road,. Kolkata 700 009, India .... [4] S Milgram, Psychology Today 1, 60 (1967). J Travers and S Milgram, ...

  14. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  15. Cloud Network Helps Stretch IT Dollars

    Science.gov (United States)

    Collins, Hilton

    2012-01-01

    No matter how many car washes or bake sales schools host to raise money, adding funds to their coffers is a recurring problem. This perpetual financial difficulty makes expansive technology purchases or changes seem like a pipe dream for school CIOs and has education technologists searching for ways to stretch money. In 2005, state K-12 school…

  16. The stretch zone of automotive steel sheets

    Indian Academy of Sciences (India)

    on steel grade, on the rolling direction as well as on the loading rate. Stretch zones ... This interaction is demonstrated at a fracture surface as a bounded transition between initiatory crack (e.g., fatigue) and either ... The materials examined in this study are three grades of thin automotive steel sheets: XSG,. HR 45 and DP.

  17. Fractional behaviour at cyclic stretch-bending

    NARCIS (Netherlands)

    Emmens, W.C.; van den Boogaard, Antonius H.; Kazantzis, A.V.; de Hosson, J.Th.M.; Kolleck, R

    2010-01-01

    The fractional behaviour at cyclic stretch-bending has been studied by performing tensile tests at long specimens that are cyclically bent at the same time, on mild steel, dual-phase steel, stainless steel, aluminium and brass. Several types of fracture are observed, these are discussed, as are the

  18. Vibrational transition moments of CH4 from first principles

    Science.gov (United States)

    Yurchenko, Sergei N.; Tennyson, Jonathan; Barber, Robert J.; Thiel, Walter

    2013-09-01

    New nine-dimensional (9D), ab initio electric dipole moment surfaces (DMSs) of methane in its ground electronic state are presented. The DMSs are computed using an explicitly correlated coupled cluster CCSD(T)-F12 method in conjunction with an F12-optimized correlation consistent basis set of the TZ-family. A symmetrized molecular bond representation is used to parameterise these 9D DMSs in terms of sixth-order polynomials. Vibrational transition moments as well as band intensities for a large number of IR-active vibrational bands of 12CH4 are computed by vibrationally averaging the ab initio dipole moment components. The vibrational wavefunctions required for these averages are computed variationally using the program TROVE and a new ‘spectroscopic’ 12CH4 potential energy surface. The new DMSs will be used to produce a hot line list for 12CH4.

  19. DNA-wrapped carbon nanotubes aligned in stretched gelatin films: Polarized resonance Raman and absorption spectroscopy study

    Science.gov (United States)

    Glamazda, A. Yu.; Plokhotnichenko, A. M.; Leontiev, V. S.; Karachevtsev, V. A.

    2017-09-01

    We present the study of DNA-wrapped single-walled carbon nanotubes (SWNTs) embedded in the stretched gelatin film by the polarized resonance Raman spectroscopy and visible-NIR optical absorption. The polarized dependent absorption spectra taken along and normal to the stretching direction demonstrate a comparatively high degree of the alignment of isolated SWNTs in the gelatin matrix. The analysis of Raman spectra of isolated SWNTs in the gelatin stretched films showed that the degree of the alignment of carbon nanotubes along the stretching direction is about 62%. The dependence of the peak position of G+-band in Raman spectra on the polarization angle θ between the polarization of the incident light and the direction of the stretching of films was revealed. This shift is explained by the different polarization dependence of the most intensive A and E1 symmetry modes within the G+-band. The performed studies of embedded DNA-wrapped nanotubes in the gelatin film show the simple method for obtaining the controlled ordered biocompatible nanotubes inside a polymer matrix. It can be used for manufacturing sizable flexible self-transparent films with integrated nanoelectrodes.

  20. Dynamic atomic contributions to infrared intensities of fundamental bands.

    Science.gov (United States)

    Silva, Arnaldo F; Richter, Wagner E; Bassi, Adalberto B M S; Bruns, Roy E

    2015-11-11

    Dynamic atomic intensity contributions to fundamental infrared intensities are defined as the scalar products of dipole moment derivative vectors for atomic displacements and the total dipole derivative vector of the normal mode. Intensities of functional group vibrations of the fluorochloromethanes can be estimated within 6.5 km mol(-1) by displacing only the functional group atoms rather than all the atoms in the molecules. The asymmetric CF2 stretching intensity, calculated to be 126.5 km mol(-1) higher than the symmetric one, is accounted for by an 81.7 km mol(-1) difference owing to the carbon atom displacement and 40.6 km mol(-1) for both fluorine displacements. Within the Quantum Theory of Atoms in Molecules (QTAIM) model differences in atomic polarizations are found to be the most important for explaining the difference in these carbon dynamic intensity contributions. Carbon atom displacements almost completely account for the differences in the symmetric and asymmetric CCl2 stretching intensities of dichloromethane, 103.9 of the total calculated value of 105.2 km mol(-1). Contrary to that found for the CF2 vibrations intramolecular charge transfer provoked by the carbon atom displacement almost exclusively explains this difference. The very similar intensity values of the symmetric and asymmetric CH2 stretching intensities in CH2F2 arise from nearly equal carbon and hydrogen atom contributions for these vibrations. All atomic contributions to the intensities for these vibrations in CH2Cl2 are very small. Sums of dynamic contributions of the individual intensities for all vibrational modes of the molecule are shown to be equal to mass weighted atomic effective charges that can be determined from atomic polar tensors evaluated from experimental infrared intensities and frequencies. Dynamic contributions for individual intensities can also be determined solely from experimental data.

  1. Vibrational, NMR and quantum chemical investigations of acetoacetanilde, 2-chloroacetoacetanilide and 2-methylacetoacetanilide

    Science.gov (United States)

    Arjunan, V.; Kalaivani, M.; Senthilkumari, S.; Mohan, S.

    2013-11-01

    The vibrational assignment and analysis of the fundamental modes of the compounds acetoacetanilide (AAA), 2-chloroacetoacetanilide (2CAAA) and 2-methylacetoacetanilide (2MAAA) have been performed. Density functional theory studies have been carried out with B3LYP method utilising 6-311++G** and cc-pVTZ basis sets to determine structural, thermodynamic and vibrational characteristics of the compounds and also to understand the influence of chloro and methyl groups on the characteristic frequencies of amide (sbnd CONHsbnd) group. Intramolecular hydrogen bond exists in acetoacetanilide and o-substituted acetoacetanilide molecules and the N⋯O distance is found to be around 2.7 Å. The 1H and 13C nuclear magnetic resonance chemical shifts of the molecules were determined and the same have been calculated using the gauge independent atomic orbital (GIAO) method. The energies of the frontier molecular orbitals have been determined. In AAA, 2CAAA and 2MAAA molecules, the nN → πCO∗ interaction between the nitrogen lone pair and the amide Cdbnd O antibonding orbital gives strong stabilization of 64.75, 62.84 and 64.18 kJ mol-1, respectively. The blue shift in amide-II band of 2MAAA is observed by 45-50 cm-1 than that of AAA. The steric effect of ortho methyl group significantly operating on the Nsbnd H bond properties. The amide-III, the Csbnd N stretching mode of methyl and chloro substituted acetoacetanilide compounds are not affected by the substitution while the amide-V band, the Nsbnd H out of plane bending mode of 2-chloroacetoacetanilide compound is shifted to a higher frequency than that of AAA. The substituent chlorine plays significantly and the blue shift in o-substituted compounds than the parent in the amide-V vibration is observed. The amide-VI, Cdbnd O out of plane bending modes of 2MAAA and 2CAAA are significantly raised than that of AAA. A blue shift of amide-VI, Cdbnd O out of plane bending modes of 2MAAA and 2CAAA than AAA is observed.

  2. EFFECTIVENESS OF PNF STRETCHING AND CYCLIC STRETCHING OF CALF TIGHTNESS ON COLLEGE GOING GIRLS

    Directory of Open Access Journals (Sweden)

    Ashlesha Sirari

    2015-06-01

    Full Text Available Background: Flexibility helps with injury prevention, the reduction of soreness following a workout, and a general sense of well-being. There are different stretching techniques and protocols for improvements in calf extensibility and flexibility. The purpose of the study was to investigate the effectiveness of two techniques i.e. CYCLIC and PNF stretching which improves calf flexibility. This study was done to find the effectiveness of calf Cyclic and PNF stretching technique to improve calf flexibility. Methods: 30 subjects with age group 21-22 years were randomly allocated to 2 groups equally. Group 1(n=15 were given CYCLIC and group 2(n=15 were given PNF stretching technique. Plantar flexion was used to measure the calf tightness which was done before and after the treatment. Treatment was given for 7 days and on the 7th day the calf tightness was again measured. Results: The mean difference of the CYCLIC is 4.6 and mean difference of PNF is 4.7 which indicate that CYCLIC and PNF both are effective to improve calf flexibility but PNF is more effective than CYCLIC to improve calf flexibility. Conclusion: The neurophysiological basis of PNF, stating that the excitatory efficient of the neuromuscular spindle or the inhibitory afferent of the Golgi tendon organ (GTO or both are responsible for the effects. During PNF stretch and isometric contraction of stretched agonists for extended period may cause activation of its neuromuscular spindle. The increase in tension created during the isometric contraction of the pre – lengthened agonist contracts concentrically. Both the fascia & the spindle of the agonist adjust to the nearly lengthened position. These impulses travel via causing post synaptic inhibition of the motor neuron to agonist increasing the tension from the GTO. These impulses can override the impulses coming from the neuromuscular spindles arousing the muscle to reflexly resist to the change in length, thus helping in lengthening

  3. Underground measurements of seismic vibrations at the SSC site

    International Nuclear Information System (INIS)

    Shiltsev, V.D.; Parkhomchuk, V.V.; Weaver, H.J.

    1995-01-01

    The results of underground measurements of seismic vibrations at the tunnel depth of the Superconducting Super Collider (SSC) site are presented. Spectral analysis of the data obtained in the frequency band from 0.05 Hz to 1500 Hz is performed. It is found that amplitudes of ambient ground motion are less than requirements for the Collider, but cultural vibrations are unacceptably large and will cause fast growth of transverse emittance of the SSC beams

  4. Measurements of ground motion and SSC dipole vibrations

    International Nuclear Information System (INIS)

    Parkhomchuk, V.V.; Shiltsev, V.D.; Weaver, H.J.

    1993-06-01

    The results of seismic ground measurements at the Superconducting Super Collider (SSC) site and investigations of vibrational properties of superconducting dipoles for the SSC are presented. Spectral analysis of the data obtained in the large frequency band from 0.05 Hz to 2000 Hz is done. Resonant behavior and the dipole-to-ground transform ratio are investigated. The influence of measured vibrations on SSC operations is considered

  5. Vibrational Spectra of Oxo-Centered Trinuclear Carboxylate Complexes

    Science.gov (United States)

    Chaisa-Ard, Nittayaporn

    1990-01-01

    Available from UMI in association with The British Library. The work presented in this thesis has been undertaken with an aim of studying vibrational spectroscopy of oxo -centered trinuclear carboxylate complexes. Resonance Raman spectra of the mixed-metal complex (Fe_2NiO(OOCCH_3 )_6(C_5H _5N)_3) (C _5H_5N) and of the complex (Fe_3O(OOCCH _3)_6(C_5 H_5N)_3) NO_3 have been recorded with different exciting lines. Mode assignments of these complexes have been made in conjunction with previously reported electronic diffuse reflectance spectra. For the (Fe_2 NiO(OOCCH_3)_6 (C_5H_5N) _3) (C_5H _5N) complex we found two components of the vibration nu_ {rm as}(Fe_2NiO) and we assigned the higher frequency as the A_1 component while the lower is the B_2 component. For the (Fe_3O(OOCCH _3)_6(C _5H_5N)_3 ) NO_3 complex we found that there is only a single band at 570 cm^{ -1} and it is visible only with the use of exciting lines below 15500 cm^{-1} . We assigned this band to nu_ {rm as}(Fe_3O), doubly degenerate (E^'). Infrared spectra of (Cr_3O(OOCCH _3)_6(H _2O)_3) Cl.6H _2O were carried out at room and low temperature and inelastic neutron scattering spectra at 20 K. INS spectra of the (Cr_3O(OOCCH _3)_6(H_2 O)_3) Cl.6H_2 O and three related complexes with the Fe _3^{III} and mixed-valence Fe_2^{III}Fe ^{II} cluster show a large number of well-resolved peaks throughout the frequency range of conventional vibrational spectroscopy, and the frequencies agree with IR and Raman measurements. As a result the mode assignments in this series of compounds can be reassessed. Synthesis and characterisation of the guanidinium salt of the mu_3-oxo hexapropionato trifluoro chromium(III) complex, (Cr_3O(OOCC _2H_5) _6F_3) (C(NH _2)_3) _2 have been done. Elemental analysis was satisfactory. Mode assignments were studied by spectroscopic methods, and the Cr-F stretching frequency was found. Finally, the structure determination was done by X-ray crystallography. The space group was found

  6. Passive Stretch Versus Active Stretch on Intervertebral Movement in Non - Specific Neck Pain

    International Nuclear Information System (INIS)

    Abd El - Aziz, A.H.; Amin, D.I.; Moustafa, I.

    2016-01-01

    Neck pain is one of the most common and painful musculoskeletal conditions. Point prevalence ranges from 6% to 22% and up to 38% of the elderly population, while lifetime prevalence ranges from 14,2% to 71%. Up till now no randomized study showed the effect between controversy of active and passive stretch on intervertebral movement. The purpose: the current study was to investigate the effect of the passive and active stretch on intervertebral movement in non - specific neck pain. Material and methods: Forty five subjects from both sexes with age range between 18 and 30 years and assigned in three groups, group I (15) received active stretch, ultrasound and TENS. Group II (15) received passive stretch, ultrasound and TENS. Group III (15) received ultrasound and TENS. The radiological assessment was used to measure rotational and translational movement of intervertebral movement before and after treatment. Results: MANOVA test was used for radiological assessment before and after treatment there was significant increase in intervertebral movement in group I as p value =0.0001. Conclusion: active stretch had a effect in increasing the intervertebral movement compared to the passive stretch

  7. HYBASE : HYperspectral BAnd SElection

    NARCIS (Netherlands)

    Schwering, P.B.W.; Bekman, H.H.P.T.; Seijen, H.H. van

    2009-01-01

    Band selection is essential in the design of multispectral sensor systems. This paper describes the TNO hyperspectral band selection tool HYBASE. It calculates the optimum band positions given the number of bands and the width of the spectral bands. HYBASE is used to assess the minimum number of

  8. Effect of hip and knee position on tensor fasciae latae elongation during stretching: An ultrasonic shear wave elastography study.

    Science.gov (United States)

    Umehara, Jun; Ikezoe, Tome; Nishishita, Satoru; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Fujita, Kosuke; Ichihashi, Noriaki

    2015-12-01

    Decreased flexibility of the tensor fasciae latae is one factor that causes iliotibial band syndrome. Stretching has been used to improve flexibility or tightness of the muscle. However, no studies have investigated the effective stretching position for the tensor fasciae latae using an index to quantify muscle elongation in vivo. The aim of this study was to investigate the effects of hip rotation and knee angle on tensor fasciae latae elongation during stretching in vivo using ultrasonic shear wave elastography. Twenty healthy men participated in this study. The shear elastic modulus of the tensor fasciae latae was calculated using ultrasonic shear wave elastography. Stretching was performed at maximal hip adduction and maximal hip extension in 12 different positions with three hip rotation conditions (neutral, internal, and external rotations) and four knee angles (0°, 45°, 90°, and 135°). Two-way analysis of variance showed a significant main effect for knee angle, but not for hip rotation. The post-hoc test for knee angle indicated that the shear elastic modulus at 90° and 135° were significantly greater than those at 0° and 45°. Our results suggest that adding hip rotation to the stretching position with hip adduction and extension may have less effect on tensor fasciae latae elongation, and that stretching at >90° of knee flexion may effectively elongate the tensor fasciae latae. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Effect of the structure of Pt-Ru/C particles on COad monolayer vibrational properties and electrooxidation kinetics

    International Nuclear Information System (INIS)

    Maillard, Frederic; Bonnefont, Antoine; Chatenet, Marian; Guetaz, Laure; Doisneau-Cottignies, Beatrice; Roussel, Herve; Stimming, Ulrich

    2007-01-01

    In this paper, we combined FTIR spectroscopy and CO ad stripping voltammetry to investigate CO ad adsorption and electrooxidation on Pt-Ru/C nanoparticles. The Pt:Ru elemental composition and the metal loading were determined by ICP-AES. The X-ray diffraction patterns of the Pt-Ru/C indicated formation of a Pt-Ru (fcc) alloy. HREM images revealed an increase in the fraction of agglomerated Pt-Ru/C particles with increasing the metal loading and showed that agglomerated Pt-Ru/C nanoparticles present structural defects such as twins or grain boundaries. In addition, isolated Pt-Ru/C nanoparticles have similar mean particle size (ca. 2.5 nm) and particle size distributions whatever the metal loading. Therefore, we could determine precisely the effect of particle agglomeration on the CO ad vibrational properties and electrooxidation kinetics. FTIR measurements revealed a main CO ad stretching band at ca. ν-bar CO L =2030cm -1 , which we ascribed to a-top CO ad on Pt domains electronically modified by the presence of Ru. As the metal loading increased, the position of this band was blue shifted by ca. 5 cm -1 and a shoulder around 2005 cm -1 developed, which was ascribed to a-top CO ad on Ru domains. The reason for this was suggested to be the increasing size of Ru domains on agglomerated Pt-Ru/C particles, which lifts dipole-dipole coupling and allows two vibrational features to be observed (CO ad /Ru, CO ad /Pt). This is evidence that FTIR spectroscopy can be used to probe small chemical fluctuations of the Pt-Ru/C surface. Finally, we comment on the CO ad electrooxidation kinetics. We observed that CO ad was converted more easily into CO 2 as the metal loading, i.e. the fraction of agglomerated Pt-Ru/C nanoparticles, increased

  10. Observation of rotational bands in neutron-rich sup 1 sup 0 sup 6 Mo nucleus

    CERN Document Server

    Xu Rui Qing; Li Ke; Yang Li Ming; Zhu Ling Yan; Gan Cui Yun; Zhang Zheng; Jiang Zhuo; Xiao Shu Dong; Hamilton, J H; Ramayya, A V; Hwang, J K; Zhang, X Q; Kormicki, J; Jones, E F; Ma, W C; Cole, J D; Aryaeinejad, R; Drigert, M W; Lee, I Y; Rasmussen, J O; Stoyer, M A; Ter-Akopian, G M; Daniel, A V

    2002-01-01

    The rotational bands up to a spin of 16 Planck constant in the neutron-rich sup 1 sup 0 sup 6 Mo nucleus have been investigated by measuring high-fold prompt gamma-ray coincidence events following spontaneous fission of sup 2 sup 5 sup 2 Cf with a Gamma-sphere detector array. The ground-state band, the one-phonon and two-phonon gamma-vibrational bands, as well as a quasi-particle band have been confirmed and expanded. The other four collective rotational bands, three proposed as two quasi-particle bands and one proposed as a beta-vibrational band, have been newly observed. The characteristics of these collective bands and the possible configurations for the quasi-particle bands are discussed

  11. Experimental Investigation on Cavitating Flow Induced Vibration Characteristics of a Low Specific Speed Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2017-01-01

    Full Text Available Cavitating flow developing in the blade channels is detrimental to the stable operation of centrifugal pumps, so it is essential to detect cavitation and avoid the unexpected results. The present paper concentrates on cavitation induced vibration characteristics, and special attention is laid on vibration energy in low frequency band, 10–500 Hz. The correlation between cavitating evolution and the corresponding vibration energy in 10–500 Hz frequency band is discussed through visualization analysis. Results show that the varying trend of vibration energy in low frequency band is unique compared with the high frequency band. With cavitation number decreasing, vibration energy reaches a local maximum at a cavitation number much larger than the 3% head drop point; after that it decreases. The varying trend is closely associated with the corresponding cavitation status. With cavitation number decreasing, cavitation could be divided into four stages. The decreasing of vibration energy, in particular cavitation number range, is caused by the partial compressible cavitation structure. From cavitation induced vibration characteristics, vibration energy rises much earlier than the usual 3% head drop criterion, and it indicates that cavitation could be detected in advance and effectively by means of cavitation induced vibration characteristics.

  12. Theoretical rotation-vibration spectrum of thioformaldehyde

    International Nuclear Information System (INIS)

    Yachmenev, Andrey; Polyak, Iakov; Thiel, Walter

    2013-01-01

    We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H 2 CS. It covers 41 809 rovibrational levels for states up to J max = 30 with vibrational band origins up to 5000 cm −1 and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments

  13. Theoretical rotation-vibration spectrum of thioformaldehyde

    Science.gov (United States)

    Yachmenev, Andrey; Polyak, Iakov; Thiel, Walter

    2013-11-01

    We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H2CS. It covers 41 809 rovibrational levels for states up to Jmax = 30 with vibrational band origins up to 5000 cm-1 and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments.

  14. Theoretical rotation-vibration spectrum of thioformaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Yachmenev, Andrey [Department of Physics and Astronomy, University College London, London, WC1E 6BT (United Kingdom); Polyak, Iakov; Thiel, Walter [Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D–45470 Mülheim an der Ruhr (Germany)

    2013-11-28

    We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H{sub 2}CS. It covers 41 809 rovibrational levels for states up to J{sub max} = 30 with vibrational band origins up to 5000 cm{sup −1} and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments.

  15. How to Stretch Your Ankle After a Sprain

    Science.gov (United States)

    ... Ankle After A Sprain How to Stretch Your Ankle After A Sprain Page Content You should perform the following stretches ... Consider these home exercises when recuperating from an ankle sprain. Perform them twice per day. While seated, bring ...

  16. Calculation of vibrational frequencies through a variational reduced-coupling approach.

    Science.gov (United States)

    Scribano, Yohann; Benoit, David M

    2007-10-28

    In this study, we present a new method to perform accurate and efficient vibrational configuration interaction computations for large molecular systems. We use the vibrational self-consistent field (VSCF) method to compute an initial description of the vibrational wave function of the system, combined with the single-to-all approach to compute a sparse potential energy surface at the chosen ab initio level of theory. A Davidson scheme is then used to diagonalize the Hamiltonian matrix built on the VSCF virtual basis. Our method is applied to the computation of the OH-stretch frequency of formic acid and benzoic acid to demonstrate the efficiency and accuracy of this new technique.

  17. Dependence of inhomogeneous vibrational linewidth broadening on attractive forces from local liquid number densities

    International Nuclear Information System (INIS)

    George, S.M.; Harris, C.B.

    1982-01-01

    The dependence of inhomogeneous vibrational linewidth broadening on attractive forces form slowly varying local liquid number densities is examined. The recently developed Schweizer--Chandler theory of vibrational dephasing is used to compute absolute inhomogeneous broadening linewidths. The computed linewidths are compared to measured inhomogeneous broadening linewidths determined using picosecond vibrational dephasing experiments. There is a similarity between correlations of the Schweizer--Chandler and George--Auweter--Harris predicted inhomogeneous broadening linewidths and the measured inhomogeneous broadening linewidths. For the methyl stretches under investigation, this correspondence suggests that the width of the number density distribution in the liquid determines the relative inhomogeneous broadening magnitudes

  18. Vibrating fuel grapple. [LMFBR

    Science.gov (United States)

    Chertock, A.J.; Fox, J.N.; Weissinger, R.B.

    A reactor refueling method is described which utilizes a vibrating fuel grapple for removing spent fuel assemblies from a reactor core. It incorporates a pneumatic vibrator in the grapple head which allows additional withdrawal capability without exceeding the allowable axial force limit. The only moving part in the vibrator is a steel ball, pneumatically driven by a gas, such as argon, around a track, with centrifugal force created by the ball being transmitted through the grapple to the assembly handling socket.

  19. Explicit Consideration of Water Molecules to Study Vibrational Circular DICHROÎSM of Monosaccharide's

    Science.gov (United States)

    Moussi, Sofiane; Ouamerali, Ourida

    2014-06-01

    Carbohydrates have multiples roles in biological systems. It has been found that the glycoside bond is fundamentally important in many aspects of chemistry and biology and forms the basis of carbohydrate chemistry. That means the stereochemical information, namely, glycosidic linkages α or β, gives an significant features of the carbohydrate glycosidation position of the glycosylic acceptor. For these reasons, much effort was made for the synthesis and analysis of the glycoside bond. Vibrational circular dichroism VCD has some advantages over conventional electronic circular dichroism (ECD) due to the applicability to all organic molecules and the reliability of ab initio quantum calculation. However, for a molecule with many chiral centers such as carbohydrates, determination of the absolute configuration tends to be difficult because the information from each stereochemical center is mixed and averaged over the spectrum. In the CH stretching region, only two VCD studies on carbohydrates have been reported and spectra--structure correlation, as determined for the glycoside band, remains to be investigated. T. Taniguchi and collaborators report that methyl glycosides exhibit a characteristic VCD peak, the sign of which solely reflects the C-1 absolute configuration. This work is a theoretical contribution to study the behaviour of VCD spectrum's of the monosaccharides when the water molecules are taken explicitly. This study is focused on six different monosaccharides in theirs absolute configuration R and S. We used the method of density functional theory DFT by means of the B3LYP hybrid functional and 6-31G * basis set.

  20. Vibrational spectroscopy of proteins

    International Nuclear Information System (INIS)

    Schwaighofer, A.

    2013-01-01

    Two important steps for the development of a biosensor are the immobilization of the biological component (e.g. protein) on a surface and the enhancement of the signal to improve the sensitivity of detection. To address these subjects, the present work describes Fourier transform infrared (FTIR) investigations of several proteins bound to the surface of an attenuated total reflection (ATR) crystal. Furthermore, new nanostructured surfaces for signal enhancement were developed for use in FTIR microscopy. The mitochondrial redox-protein cytochrome c oxidase (CcO) was incorporated into a protein-tethered bilayer lipid membrane (ptBLM) on an ATR crystal featuring a roughened two-layer gold surface for signal enhancement. Electrochemical excitation by periodic potential pulses at different modulation frequencies was followed by time-resolved FTIR spectroscopy. Phase sensitive detection was used for deconvolution of the IR spectra into vibrational components. A model based on protonation-dependent chemical reaction kinetics could be fitted to the time evolution of IR bands attributed to several different redox centers of the CcO. Further investigations involved the odorant binding protein 14 (OBP14) of the honey bee (Apis mellifera), which was studied using ATR-FTIR spectroscopy and circular dichroism. OBP14 was found to be thermally stable up to 45 °C, thus permitting the potential application of this protein for the fabrication of biosensors. Thermal denaturation measurements showed that odorant binding increases the thermal stability of the OBP-odorant complex. In another project, plasmonic nanostructures were fabricated that enhance the absorbance in FTIR microscopy measurements. The nanostructures are composed of an array of round-shaped insulator and gold discs on top of a continuous gold layer. Enhancement factors of up to ⁓125 could be observed with self-assembled monolayers of dodecanethiol molecules immobilized on the gold surface (author) [de

  1. Structure, vibrations, and hydrogen bond parameters of dibenzotetraaza[14]annulene

    Science.gov (United States)

    Gawinkowski, S.; Eilmes, J.; Waluk, J.

    2010-07-01

    Geometry and vibrational structure of dibenzo[ b, i][1,4,8,11]tetraaza[14]annulene (TAA) have been studied using infrared and Raman spectroscopy combined with quantum-chemical calculations. The assignments were proposed for 106 out of the total of 108 TAA vibrations, based on comparison of the theoretical predictions with the experimental data obtained for the parent molecule and its isotopomer in which the NH protons were replaced by deuterons. Reassignments were suggesteded for the NH stretching and out-of-plane vibrations. The values of the parameters of the intramolecular NH⋯N hydrogen bonds were analysed in comparison with the corresponding data for porphyrin and porphycene, molecules with the same structural motif, a cavity composed of four nitrogen atoms and two inner protons. Both experiment and calculations suggest that the molecule of TAA is not planar and is present in a trans tautomeric form, with the protons located on the opposite nitrogen atoms.

  2. Time-stretch microscopy based on time-wavelength sequence reconstruction from wideband incoherent source

    International Nuclear Information System (INIS)

    Zhang, Chi; Xu, Yiqing; Wei, Xiaoming; Tsia, Kevin K.; Wong, Kenneth K. Y.

    2014-01-01

    Time-stretch microscopy has emerged as an ultrafast optical imaging concept offering the unprecedented combination of the imaging speed and sensitivity. However, dedicated wideband and coherence optical pulse source with high shot-to-shot stability has been mandated for time-wavelength mapping—the enabling process for ultrahigh speed wavelength-encoded image retrieval. From the practical point of view, exploiting methods to relax the stringent requirements (e.g., temporal stability and coherence) for the source of time-stretch microscopy is thus of great value. In this paper, we demonstrated time-stretch microscopy by reconstructing the time-wavelength mapping sequence from a wideband incoherent source. Utilizing the time-lens focusing mechanism mediated by a narrow-band pulse source, this approach allows generation of a wideband incoherent source, with the spectral efficiency enhanced by a factor of 18. As a proof-of-principle demonstration, time-stretch imaging with the scan rate as high as MHz and diffraction-limited resolution is achieved based on the wideband incoherent source. We note that the concept of time-wavelength sequence reconstruction from wideband incoherent source can also be generalized to any high-speed optical real-time measurements, where wavelength is acted as the information carrier

  3. Implausibility of the vibrational theory of olfaction.

    Science.gov (United States)

    Block, Eric; Jang, Seogjoo; Matsunami, Hiroaki; Sekharan, Sivakumar; Dethier, Bérénice; Ertem, Mehmed Z; Gundala, Sivaji; Pan, Yi; Li, Shengju; Li, Zhen; Lodge, Stephene N; Ozbil, Mehmet; Jiang, Huihong; Penalba, Sonia F; Batista, Victor S; Zhuang, Hanyi

    2015-05-26

    The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse ORs, responded similarly to normal, deuterated, and (13)C isotopomers of their respective ligands, paralleling our results with the musk receptor OR5AN1. These findings suggest that the proposed vibration theory does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other ORs examined. Also, contrary to the vibration theory predictions, muscone-d30 lacks the 1,380- to 1,550-cm(-1) IR bands claimed to be essential for musk odor. Furthermore, our theoretical analysis shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of nonodorant molecular vibrational modes. These and other concerns about electron transfer at ORs, together with our extensive experimental data, argue against the plausibility of the vibration theory.

  4. Transparent conducting film: Effect of mechanical stretching to ...

    Indian Academy of Sciences (India)

    Administrator

    posite was fixed to a tabletop clamp and unidirectionally stretched after cutting the paper support at two opposite sides. To hold the film under the stretched condition, both edges of stretched CNT-mat/transparent-film composite was then adhered to a PMMA substrate by epoxy glue and both the sheet resistance and the ...

  5. Effects of dynamic stretches on Isokinetic hamstring and Quadriceps ...

    African Journals Online (AJOL)

    In conclusion, dynamic stretches have positive effects on muscle strength, H/Q ratios and ROM. Therefore, dynamic stretches may increase performance and reduce the risk of injury to athletes. Keywords: Quadriceps; Hamstrings; Muscles Isokinetic; Dynamic stretches. South African Journal for Research in Sport, Physical ...

  6. Stretched cell cycle model for proliferating lymphocytes

    Science.gov (United States)

    Dowling, Mark R.; Kan, Andrey; Heinzel, Susanne; Zhou, Jie H. S.; Marchingo, Julia M.; Wellard, Cameron J.; Markham, John F.; Hodgkin, Philip D.

    2014-01-01

    Stochastic variation in cell cycle time is a consistent feature of otherwise similar cells within a growing population. Classic studies concluded that the bulk of the variation occurs in the G1 phase, and many mathematical models assume a constant time for traversing the S/G2/M phases. By direct observation of transgenic fluorescent fusion proteins that report the onset of S phase, we establish that dividing B and T lymphocytes spend a near-fixed proportion of total division time in S/G2/M phases, and this proportion is correlated between sibling cells. This result is inconsistent with models that assume independent times for consecutive phases. Instead, we propose a stretching model for dividing lymphocytes where all parts of the cell cycle are proportional to total division time. Data fitting based on a stretched cell cycle model can significantly improve estimates of cell cycle parameters drawn from DNA labeling data used to monitor immune cell dynamics. PMID:24733943

  7. String Stretching, Frequency Modulation, and Banjo Clang

    OpenAIRE

    Politzer, David

    2014-01-01

    The banjo’s floating bridge, string break angle, and flexible drumhead all contribute to substantial audio range frequency modulation. From the world of electronic music synthesis, it is known that modulating higher frequency sounds with lower acoustic frequencies leads to metallic and bell-like tone. The mechanics of the banjo does just that quite naturally, modulating fundamentals and harmonics with the motion of the bridge. In technical terms, with a floating bridge, string stretching is f...

  8. The stretch zone of automotive steel sheets

    Indian Academy of Sciences (India)

    The stretch zone of automotive steel sheets. L' AMBRIŠKO1,∗ and L PEŠEK2. 1Institute of Structural Engineering, Faculty of Civil Engineering,. Technical University of Košice, Vysokoškolská 4, 042 00 Košice, Slovak Republic. 2Department of Materials Science, Faculty of Metallurgy,. Technical University of Košice, Letná 9, ...

  9. Low-frequency vibration control of floating slab tracks using dynamic vibration absorbers

    Science.gov (United States)

    Zhu, Shengyang; Yang, Jizhong; Yan, Hua; Zhang, Longqing; Cai, Chengbiao

    2015-09-01

    This study aims to effectively and robustly suppress the low-frequency vibrations of floating slab tracks (FSTs) using dynamic vibration absorbers (DVAs). First, the optimal locations where the DVAs are attached are determined by modal analysis with a finite element model of the FST. Further, by identifying the equivalent mass of the concerned modes, the optimal stiffness and damping coefficient of each DVA are obtained to minimise the resonant vibration amplitudes based on fixed-point theory. Finally, a three-dimensional coupled dynamic model of a metro vehicle and the FST with the DVAs is developed based on the nonlinear Hertzian contact theory and the modified Kalker linear creep theory. The track irregularities are included and generated by means of a time-frequency transformation technique. The effect of the DVAs on the vibration absorption of the FST subjected to the vehicle dynamic loads is evaluated with the help of the insertion loss in one-third octave frequency bands. The sensitivities of the mass ratio of DVAs and the damping ratio of steel-springs under the floating slab are discussed as well, which provided engineers with the DVA's adjustable room for vibration mitigation. The numerical results show that the proposed DVAs could effectively suppress low-frequency vibrations of the FST when tuned correctly and attached properly. The insertion loss due to the attachment of DVAs increases as the mass ratio increases, whereas it decreases with the increase in the damping ratio of steel-springs.

  10. Spontaneous bending of pre-stretched bilayers.

    Science.gov (United States)

    DeSimone, Antonio

    2018-01-01

    We discuss spontaneously bent configurations of pre-stretched bilayer sheets that can be obtained by tuning the pre-stretches in the two layers. The two-dimensional nonlinear plate model we use for this purpose is an adaptation of the one recently obtained for thin sheets of nematic elastomers, by means of a rigorous dimensional reduction argument based on the theory of Gamma-convergence (Agostiniani and DeSimone in Meccanica. doi:10.1007/s11012-017-0630-4, 2017, Math Mech Solids. doi:10.1177/1081286517699991, arXiv:1509.07003, 2017). We argue that pre-stretched bilayer sheets provide us with an interesting model system to study shape programming and morphing of surfaces in other, more complex systems, where spontaneous deformations are induced by swelling due to the absorption of a liquid, phase transformations, thermal or electro-magnetic stimuli. These include bio-mimetic structures inspired by biological systems from both the plant and the animal kingdoms.

  11. Dynamics and structure of stretched flames

    Energy Technology Data Exchange (ETDEWEB)

    Law, C.K. [Princeton Univ., NJ (United States)

    1993-12-01

    This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

  12. Stretch Moduli of Ribonucleotide Embedded Short DNAs

    Science.gov (United States)

    Chiu, Hsiang-Chih; Koh, Kyung Duk; Riedo, Elisa; Storici, Francesca

    2013-03-01

    Understanding the mechanical properties of DNA is essential to comprehending the dynamics of many cellular functions. DNA deformations are involved in many mechanisms when genetic information needs to be stored and used. In addition, recent studies have found that Ribonucleotides (rNMPs) are among the most common non-standard nucleotides present in DNA. The presences of rNMPs in DNA might cause mutation, fragility or genotoxicity of chromosome but how they influence the structure and mechanical properties of DNA remains unclear. By means of Atomic Force Microscopy (AFM) based single molecule spectroscopy, we measure the stretch moduli of double stranded DNAs (dsDNA) with 30 base pairs and 5 equally embedded rNMPs. The dsDNAs are anchored on gold substrate via thiol chemistry, while the AFM tip is used to pick up and stretch the dsDNA from its free end through biotin-streptavidin bonding. Our preliminary results indicate that the inclusion of rNMPs in dsDNA might significantly change its stretch modulus, which might be important in some biological processes.

  13. Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility

    Science.gov (United States)

    Wong, Del P.; Chaouachi, Anis; Lau, Patrick W.C.; Behm, David G.

    2011-01-01

    This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key points The duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). No significant differences in RSA and COD between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. PMID:24149890

  14. Local Environment and Interactions of Liquid and Solid Interfaces Revealed by Spectral Line Shape of Surface Selective Nonlinear Vibrational Probe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun-Li; Fu, Li; Chase, Zizwe A.; Gan, Wei; Wang, Hong-Fei

    2016-11-10

    Vibrational spectral lineshape contains important detailed information of molecular vibration and reports its specific interactions and couplings to its local environment. In this work, recently developed sub-1 cm-1 high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) was used to measure the -C≡N stretch vibration in the 4-n-octyl-4’-cyanobiphenyl (8CB) Langmuir or Langmuir-Blodgett (LB) monolayer as a unique vibrational probe, and the spectral lineshape analysis revealed the local environment and interactions at the air/water, air/glass, air/calcium fluoride and air/-quartz interfaces for the first time. The 8CB Langmuir or LB film is uniform and the vibrational spectral lineshape of its -C≡N group has been well characterized, making it a good choice as the surface vibrational probe. Lineshape analysis of the 8CB -C≡N stretch SFG vibrational spectra suggests the coherent vibrational dynamics and the structural and dynamic inhomogeneity of the -C≡N group at each interface are uniquely different. In addition, it is also found that there are significantly different roles for water molecules in the LB films on different substrate surfaces. These results demonstrated the novel capabilities of the surface nonlinear spectroscopy in characterization and in understanding the specific structures and chemical interactions at the liquid and solid interfaces in general.

  15. Broadband characteristics of vibration energy harvesting using one-dimensional phononic piezoelectric cantilever beams

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhongsheng, E-mail: czs_study@sina.com [Key Laboratory of Science and Technology on Integrated Logistics Support, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China); Yang Yongmin; Lu Zhimiao; Luo Yanting [Key Laboratory of Science and Technology on Integrated Logistics Support, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China)

    2013-02-01

    Nowadays broadband vibration energy harvesting using piezoelectric effect has become a research hotspot. The innovation in this paper is the widening of the resonant bandwidth of a piezoelectric harvester based on phononic band gaps, which is called one-dimensional phononic piezoelectric cantilever beams (PPCBs). Broadband characteristics of one-dimensional PPCBs are analyzed deeply and the vibration band gap can be calculated. The effects of different parameters on the vibration band gap are presented by both numerical and finite element simulations. Finally experimental tests are conducted to validate the proposed method. It can be concluded that it is feasible to use the PPCB for broadband vibration energy harvesting and there should be a compromise among related parameters for low-frequency vibrations.

  16. Multiscale studies on the nonlinear vibration of delaminated composite laminates-global vibration mode with micro buckles on the interfaces.

    Science.gov (United States)

    Xue, Jianghong; Xia, Fei; Ye, Jun; Zhang, Jianwen; Chen, Shuhua; Xiong, Ying; Tan, Zuyuan; Liu, Renhuai; Yuan, Hong

    2017-06-30

    This paper presents a multiscale approach to study the nonlinear vibration of fiber reinforced composite laminates containing an embedded, through-width delamination dividing the laminate into four sub-laminates. The equations of motion are established from macroscopic nonlinear mechanics for plates and shells and micro-mechanics of composite material to allow for the influences of large amplitude, membrane stretching in the neutral plane, and the interactions of the sublaminates. Analytical solutions obtained in this paper reveal that the interaction penalty at the interfaces plays a coupling effect between sublaminates, which eventually alters the vibration characters of the four-sublaminate lamina in macroscopic and microscopic mechanism. From a macro perspective, sub-laminates above and below the delamination vibrate in exactly the same mode in spite of their different stiffness and the four-sublaminate lamina has a consistent global vibration mode. In accompanying with the macro vibration, micro buckles occur on the interfaces of the delamination with amplitude about 10 -3 times of that of the global mode. It is found that the vibration frequency is an eigenvalue of the delaminated lamina determined only by the geometry of the delamination. Authentication of the multiscale study is fulfilled by comparing the analytical solutions with the FEA results.

  17. Reduced Near-Resonant Vibrational Coupling at the Surfaces of Liquid Water and Ice.

    Science.gov (United States)

    Smit, Wilbert J; Versluis, Jan; Backus, Ellen H G; Bonn, Mischa; Bakker, Huib J

    2018-02-26

    We study the resonant interaction of the OH stretch vibrations of water molecules at the surfaces of liquid water and ice using heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy. By studying different isotopic mixtures of H 2 O and D 2 O, we vary the strength of the interaction, and we monitor the resulting effect on the HD-SFG spectrum of the OH stretch vibrations. We observe that the near-resonant coupling effects are weaker at the surface than in the bulk, both for water and ice, indicating that for both phases of water the OH vibrations are less strongly delocalized at the surface than in the bulk.

  18. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    Lalanne, Christian

    2014-01-01

    Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

  19. Model Indepedent Vibration Control

    OpenAIRE

    Yuan, Jing

    2010-01-01

    A NMIFC system is proposed for broadband vibration control. It has two important features. Feature F1 is that the NMIFC is stable without introducing any invasive effects, such as probing signals or controller perturbations, into the vibration system; feature F2 is

  20. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration...

  1. Flow induced vibrations of piping

    International Nuclear Information System (INIS)

    Gibert, R.J.; Axisa, F.

    1977-01-01

    This paper presents a method to take into account the inertial effects and the fluid compressibility by solving a coupled mechanical-acoustical problem: the computer code TEDEL of the C.E.A./D.E.M.T. System, based on the finite-element method, has been extended to calculate simultaneously the pressure fluctuations in the fluid and the vibrations of the pipe. By this way the mechanical-acoustical coupled eigenmodes of any piping system can be obtained. These eigenmodes are used to determine the response of the system to various sources (acoustical sources or forces exciting directly the structure). Equations have been written in the hypothesis that acoustical wave lengths remain large compared to the diameter of the pipe. Indeed this is largely verified in almost practical cases. The method has been checked by an experiment performed on the GASCOGNE loop at D.E.M.T. The piping system under test consist of a tube with four elbows. The circuit is ended at each extremity by a large vessel which performs acoustical isolation by generating modes for the pressure. Excitation of the circuit is caused by a valve located near the downstream vessel. This provide an efficient localised broad band acoustical source. The comparison between the test results and the calculations has shown that the low frequency resonant characteristics of the pipe and the vibrational amplitude at various flow-rates can be correctly predicted [fr

  2. Handbook Of Noise And Vibration

    International Nuclear Information System (INIS)

    1995-12-01

    This book is about noise and vibration. The first chapter has explanations of noise such as basic of sound, influence of noise, assessment of noise, measurement of prevention of noise and technology, case of noise measurement and soundproof. The second chapter describes vibration with outline, theory of vibration, interpretation of vibration, measurement for reduction of vibration, case of design of protection against vibration. It deals with related regulation and method of measurement.

  3. Dispersion-corrected first-principles calculation of terahertz vibration, and evidence for weak hydrogen bond formation

    Science.gov (United States)

    Takahashi, Masae; Ishikawa, Yoichi; Ito, Hiromasa

    2013-03-01

    A weak hydrogen bond (WHB) such as CH-O is very important for the structure, function, and dynamics in a chemical and biological system WHB stretching vibration is in a terahertz (THz) frequency region Very recently, the reasonable performance of dispersion-corrected first-principles to WHB has been proven. In this lecture, we report dispersion-corrected first-principles calculation of the vibrational absorption of some organic crystals, and low-temperature THz spectral measurement, in order to clarify WHB stretching vibration. The THz frequency calculation of a WHB crystal has extremely improved by dispersion correction. Moreover, the discrepancy in frequency between an experiment and calculation and is 10 1/cm or less. Dispersion correction is especially effective for intermolecular mode. The very sharp peak appearing at 4 K is assigned to the intermolecular translational mode that corresponds to WHB stretching vibration. It is difficult to detect and control the WHB formation in a crystal because the binding energy is very small. With the help of the latest intense development of experimental and theoretical technique and its careful use, we reveal solid-state WHB stretching vibration as evidence for the WHB formation that differs in respective WHB networks The research was supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant No. 22550003).

  4. Vibrations of rotating machinery

    CERN Document Server

    Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

    2017-01-01

    This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

  5. The Relevance of Stretch Intensity and Position: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Nikos eApostolopoulos

    2015-08-01

    Full Text Available Stretching exercises to increase the range of motion (ROM of joints have been used by sports coaches and medical professionals for improving performance and rehabilitation. The ability of connective and muscular tissues to change their architecture in response to stretching is important for their proper function, repair and performance. Given the dearth of relevant data in the literature, this review examined two key elements of stretching: stretch intensity and stretch position; and their significance to ROM, delayed onset muscle soreness (DOMS, and inflammation in different populations. A search of three databases, Pub-Med, Google Scholar, and Cochrane Reviews, identified 152 articles, which were subsequently categorized into four groups; athletes (n = 24, clinical (n = 29, elderly (n = 12, and general population (n = 87. The use of different populations facilitated a wider examination of the stretching components and their effects. All 152 articles incorporated information regarding duration, frequency and stretch position, whereas only 79 referred to the intensity of stretching and 22 of these 79 studies were deemed high quality. It appears that the intensity of stretching is relatively under-researched, and the importance of body position and its influence on stretch intensity, is largely unknown. In conclusion, this review has highlighted areas for future research, including stretch intensity and position and their effect on musculo-tendinous tissue, in relation to the sensation of pain, delayed onset muscle soreness, inflammation, as well as muscle health and performance

  6. Hamstring Stiffness Returns More Rapidly After Static Stretching Than Range of Motion, Stretch Tolerance, and Isometric Peak Torque.

    Science.gov (United States)

    Hatano, Genki; Suzuki, Shigeyuki; Matsuo, Shingo; Kataura, Satoshi; Yokoi, Kazuaki; Fukaya, Taizan; Fujiwara, Mitsuhiro; Asai, Yuji; Iwata, Masahiro

    2017-12-18

    Hamstring injuries are common, and lack of hamstring flexibility may predispose to injury. Static stretching increases range of motion (ROM) but also results in reduced muscle strength after stretching. The effects of stretching on the hamstring muscles and the duration of these effects remain unclear. To determine the effects of static stretching on the hamstrings and the duration of these effects. Randomized crossover study. University laboratory. Twenty-four healthy volunteers. We measured the torque-angle relationship (ROM, passive torque (PT) at the onset of pain, and passive stiffness) and isometric muscle force using an isokinetic dynamometer. After a 60-minute rest, the ROM of the dynamometer was set at maximum tolerable intensity; this position was maintained for 300 seconds while static passive torque (SPT) was measured continuously. We remeasured the torque-angle relationship and isometric muscle force after rest periods of 10, 20, and 30 minutes. Change in SPT during stretching; changes in ROM, PT at the onset of pain, passive stiffness, and isometric muscle force before stretching compared with 10, 20, and 30 minutes after stretching. SPT decreased significantly during stretching. Passive stiffness decreased significantly 10 and 20 minutes after stretching, but there was no significant pre- vs. post-stretching difference after 30 minutes. PT at the onset of pain and ROM increased significantly after stretching at all rest intervals, while isometric muscle force decreased significantly after all rest intervals. The effect of static stretching on passive stiffness of the hamstrings was not maintained as long as the changes in ROM, stretch tolerance, and isometric muscle force. Therefore, frequent stretching is necessary to improve the viscoelasticity of the muscle-tendon unit. Muscle force was decreased for 30 minutes after stretching; this should be considered prior to activities requiring maximal muscle strength.

  7. SHORT DURATIONS OF STATIC STRETCHING WHEN COMBINED WITH DYNAMIC STRETCHING DO NOT IMPAIR REPEATED SPRINTS AND AGILITY

    OpenAIRE

    Del P. Wong; Anis Chaouachi; Patrick W.C. Lau; David G. Behm

    2011-01-01

    This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performe...

  8. Vibrational analysis of Fourier transform spectrum of the B u )–X g ...

    Indian Academy of Sciences (India)

    improved by putting the wave number of band origins in Deslandre table. The vibrational analysis was supported by determining the Franck–Condon factor and r-centroid values. Keywords. Fourier transform spectroscopy; electronic spectrum of selenium dimer; vibrational analysis; Franck–Condon factor; r-centroid values.

  9. Vibrational analysis of Fourier transform spectrum of the B 3− u (0

    Indian Academy of Sciences (India)

    ... microwave, was recorded on BOMEM DA8 Fourier transform spectrometer at an apodized resolution of 0.035 cm-1. Vibrational constants were improved by putting the wave number of band origins in Deslandre table. The vibrational analysis was supported by determining the Franck–Condon factor and -centroid values.

  10. O modelo AM1 na previsão de frequências vibracionais The vibration frequencies predicted by the AM1 model

    Directory of Open Access Journals (Sweden)

    João Carlos Silva Ramos

    1999-09-01

    Full Text Available We analyse vibrational frequencies of 168 compounds with the AM1 model concerning its experimentally observed gaseous frequencies. Stretching of CH, NH, OH and CO bonds, its related bending frequencies, and the CC frame movements are the studied vibrations. The results show problems with the AM1 vibrational splittings. Often symmetric stretching frequencies, like in CH3, CH2 and NH3, appear switched with the corresponding antisymmetrical ones. Among the studied vibrations many stretchings are overestimated, while bendings oscillate around experimental values. Fluorine stretchings, NN, OO, CH, double and triples CC bonds and cyclic hydrocarbon breathing modes are always overestimated while torsions, umbrella modes and OH/SH stretching are, in average, underestimated. Graphical analysis show that compounds with the lowest molecular masses are the ones with the largest difference to the experimental values. From our results it is not possible to fit confortably the calculated frequencies by a simple linear relationship of the type, n(obs=a*n(AM1. Better aggreement is obtained when different curves are adjusted for the stretching and bending modes, and when a complete linear function is used. Among our studies the best obtained statistical results are for CH, NH and OH. The conclusions obtained in this work will improve the AM1 calculated frequencies leading to accurate results for these properties.

  11. Efficacy of static stretching and proprioceptive neuromuscular facilitation stretch on hamstrings length after a single session.

    Science.gov (United States)

    O'Hora, John; Cartwright, Abigail; Wade, Clive D; Hough, Alan D; Shum, Gary L K

    2011-06-01

    A number of studies have investigated the efficacy of several repetitions of proprioceptive neuromuscular facilitation stretching (PNF) and static stretching (SS). However, there is limited research comparing the effects of a single bout of these stretching maneuvers. The aim of this study was to compare the effectiveness of a single bout of a therapist-applied 30-second SS vs. a single bout of therapist-applied 6-second hamstring (agonist) contract PNF. Forty-five healthy subjects between the ages of 21 and 35 were randomly allocated to 1 of the 2 stretching groups or a control group, in which no stretching was received. The flexibility of the hamstring was determined by a range of passive knee extension, measured using a universal goniometer, with the subject in the supine position and the hip at 90° flexion, before and after intervention. A significant increase in knee extension was found for both intervention groups after a single stretch (SS group = 7.53°, p < 0.01 and PNF group = 11.80°, p < 0.01). Both interventions resulted in a significantly greater increase in knee extension when compared to the control group (p < 0.01). The PNF group demonstrated significantly greater gains in knee extension compared to the SS group (mean difference 4.27°, p < 0.01). It can be concluded that a therapist applied SS or PNF results in a significant increase in hamstring flexibility. A hamstring (agonist) contract PNF is more effective than an SS in a single stretching session. These findings are important to physiotherapists or trainers working in clinical and sporting environments. Where in the past therapists may have spent time conducting multiple repetitions of a PNF and an SS, a single bout of either technique may be considered just as effective. A key component of the study methodology was the exclusion of a warm-up period before stretching. Therefore, the findings of efficacy of a single PNF are of particular relevance in sporting environments and busy clinical

  12. SHORT DURATIONS OF STATIC STRETCHING WHEN COMBINED WITH DYNAMIC STRETCHING DO NOT IMPAIR REPEATED SPRINTS AND AGILITY

    Directory of Open Access Journals (Sweden)

    Del P. Wong

    2011-06-01

    Full Text Available This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA and change of direction (COD. Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s. Three dynamic stretching exercises of 30 s duration were then performed (90 s total. Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p < 0.001. However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (< 90 s static stretching may not have provided sufficient stimulus to elicit performance impairments

  13. Dynamic structure factor of vibrating fractals.

    Science.gov (United States)

    Reuveni, Shlomi; Klafter, Joseph; Granek, Rony

    2012-02-10

    Motivated by novel experimental work and the lack of an adequate theory, we study the dynamic structure factor S(k,t) of large vibrating fractal networks at large wave numbers k. We show that the decay of S(k,t) is dominated by the spatially averaged mean square displacement of a network node, which evolves subdiffusively in time, ((u[over →](i)(t)-u[over →](i)(0))(2))∼t(ν), where ν depends on the spectral dimension d(s) and fractal dimension d(f). As a result, S(k,t) decays as a stretched exponential S(k,t)≈S(k)e(-(Γ(k)t)(ν)) with Γ(k)∼k(2/ν). Applications to a variety of fractal-like systems are elucidated.

  14. Optical stretching on chip with acoustophoretic prefocusing

    DEFF Research Database (Denmark)

    Khoury Arvelo, Maria; Laub Busk, L.; Bruus, Henrik

    2012-01-01

    prefocusing. This focusing mechanism aims for target particles to always ow in the correct height relative to the optical stretcher, and is induced by a piezo-electric ultrasound transducer attached underneath the chip and driven at a frequency leading to a vertical standing ultrasound wave...... in the microchannel. Trapping and manipulation is demonstrated for dielectric beads. In addition, we show trapping, manipulation and stretching of red blood cells and vesicles, whereby we extract the elastic properties of these objects. Our design points towards the construction of a low-cost, high-throughput lab-on-a-chip...

  15. Viscous flows stretching and shrinking of surfaces

    CERN Document Server

    Mehmood, Ahmer

    2017-01-01

    This authored monograph provides a detailed discussion of the boundary layer flow due to a moving plate. The topical focus lies on the 2- and 3-dimensional case, considering axially symmetric and unsteady flows. The author derives a criterion for the self-similar and non-similar flow, and the turbulent flow due to a stretching or shrinking sheet is also discussed. The target audience primarily comprises research experts in the field of boundary layer flow, but the book will also be beneficial for graduate students.

  16. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author at the Uni......This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....

  17. Coherent vibrational dynamics

    CERN Document Server

    Lanzani, Guglielmo; De Silvestri, Sandro

    2007-01-01

    Vibrational spectroscopy is a powerful investigation tool for a wide class of materials covering diverse areas in physics, chemistry and biology. The continuous development in the laser field regarding ultrashort pulse generation has led to the possibility of producing light pulses that can follow vibrational motion coupled to the electronic transitions in molecules and solids in real time. Aimed at researchers and graduate students using vibrational spectroscopy, this book provides both introductory chapters as well as more advanced contents reporting on recent progress. It also provides a good starting point for scientists seeking a sound introduction to ultrafast optics and spectroscopic techniques.

  18. Vibration Analysis and the Accelerometer

    Science.gov (United States)

    Hammer, Paul

    2011-01-01

    Have you ever put your hand on an electric motor or motor-driven electric appliance and felt it vibrate? Ever wonder why it vibrates? What is there about the operation of the motor, or the object to which it is attached, that causes the vibrations? Is there anything "regular" about the vibrations, or are they the result of random causes? In this…

  19. Twist-stretch profiles of DNA chains

    Science.gov (United States)

    Zoli, Marco

    2017-06-01

    Helical molecules change their twist number under the effect of a mechanical load. We study the twist-stretch relation for a set of short DNA molecules modeled by a mesoscopic Hamiltonian. Finite temperature path integral techniques are applied to generate a large ensemble of possible configurations for the base pairs of the sequence. The model also accounts for the bending and twisting fluctuations between adjacent base pairs along the molecules stack. Simulating a broad range of twisting conformation, we compute the helix structural parameters by averaging over the ensemble of base pairs configurations. The method selects, for any applied force, the average twist angle which minimizes the molecule’s free energy. It is found that the chains generally over-twist under an applied stretching and the over-twisting is physically associated to the contraction of the average helix diameter, i.e. to the damping of the base pair fluctuations. Instead, assuming that the maximum amplitude of the bending fluctuations may decrease against the external load, the DNA molecule first over-twists for weak applied forces and then untwists above a characteristic force value. Our results are discussed in relation to available experimental information albeit for kilo-base long molecules.

  20. Microgyroscope with Vibrating Post as Rotation Transducer

    Science.gov (United States)

    Tang, Tony K.; Gutierrez, Roman

    2003-01-01

    The figure depicts a micromachined silicon vibratory gyroscope that senses rotation about its z axis. The rotation-sensitive vibratory element is a post oriented (when at equilibrium) along the z axis and suspended at its base by thin, flexible silicon bands oriented along the x and y axes, respectively. Unlike in the vibratory microgyroscopes described in the immediately preceding article ["Cloverleaf Vibratory Microgyroscope With Integrated Post" (NPO-20688)] and other previous articles in NASA Tech Briefs, the rotation-sensitive vibratory element does not include a cloverleaf-shaped structure that lies (when at equilibrium) in the x-y plane. As in the cases of the previously reported vibratory microgyroscopes, vibrations of the rotation-sensitive vibratory element are excited electrostatically, the vibrations are measured by use of capacitive proximity sensors, and the rate of rotation along the axis of sensitivity is deduced from the effect of the Coriolis force upon the vibrations. To create electrodes for electrostatic excitation and capacitive sensing of vibrations, portions of the facing surfaces of the post and of the four stationary members that surround the post are rendered electrically conductive; this can be accomplished by either depositing metal films or else doping the silicon in the affected areas.

  1. laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 m and 10.6 m regions of CO2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with conventional low ...

  2. CO 2 laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 m and 10.6 m regions of CO2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with conventional low ...

  3. The low frequency vibrations of hydrogen bonded adipic acid crystals

    Science.gov (United States)

    Yaremko, A. M.; Silvi, B.; Zelsmann, H. R.

    2000-03-01

    The low frequency vibrational spectrum of crystalline adipic acid has been investigated in the range 20-450 cm -1 at room and low temperatures. The experimental results are compared to ab initio results on a model asymmetric unit. It is shown that the doublet and quartet structures observed for several bands are due to Davydov splitting and Fermi resonance effects.

  4. CO laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    vibrations of these molecules for assignments of PA spectra. Keywords. Laser photoacoustic ... The assignment of these bands have been done in the light ofab initio calculations of normal mode frequencies. ..... a family of iteration methods called quasi-Newton methods which lead to very efficient geometry optimization.

  5. CO laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    Abstract. Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 µm and 10.6 µm regions of CO2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with ...

  6. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  7. The vibration discomfort of standing people: evaluation of multi-axis vibration.

    Science.gov (United States)

    Thuong, Olivier; Griffin, Michael J

    2015-01-01

    Few studies have investigated discomfort caused by multi-axis vibration and none has explored methods of predicting the discomfort of standing people from simultaneous fore-and-aft, lateral and vertical vibration of a floor. Using the method of magnitude estimation, 16 subjects estimated their discomfort caused by dual-axis and tri-axial motions (octave-bands centred on either 1 or 4 Hz with various magnitudes in the fore-and-aft, lateral and vertical directions) and the discomfort caused by single-axis motions. The method of predicting discomfort assumed in current standards (square-root of the sums of squares of the three components weighted according to their individual contributions to discomfort) provided reasonable predictions of the discomfort caused by multi-axis vibration. Improved predictions can be obtained for specific stimuli, but no single simple method will provide accurate predictions for all stimuli because the rate of growth of discomfort with increasing magnitude of vibration depends on the frequency and direction of vibration.

  8. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M

    2013-01-01

    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  9. A vibration sieve

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S.A.; Denisenko, V.V.; Dzhalalov, M.G.; Kirichek, F.P.; Pitatel, Yu.A.; Prokopov, L.I.; Tikhonov, Yu.P.

    1982-01-01

    A vibration sieve is proposed which includes a vibration drive, a body and a screen installed on shock absorbers, a device for washing out the screen, and a subassembly for loading the material. To increase the operational reliability and effectiveness of the vibration sieve by improving the cleaning of the screen, the loading subassembly is equipped with a baffle with a lever which is hinged to it. The device for washing out the screen is made in the form of an electromagnet with a connecting rod, a switch and an eccentric, a friction ratchet mechanism and sprinkling systems. Here, the latter are interconnected, using a connecting rod, while the sprinkling system is installed on rollers under the screen. The electromagnetic switch is installed under the lever. The body is made with grooves for installing the sprinkling system. The vibration sieve is equipped with a switch which interacts with the connecting rod. The friction ratchet mechanism is equipped with a lug.

  10. Effects of stretching the scalene muscles on slow vital capacity.

    Science.gov (United States)

    Lee, Juncheol; Hwang, Sehee; Han, Seungim; Han, Dongwook

    2016-06-01

    [Purpose] The purpose of this study was to examine whether stretching of the scalene muscles would improve slow vital capacity (SVC). [Subjects and Methods] The subjects of this study were 20 healthy female students to whom the study's methods and purpose were explained and their agreement for participation was obtained. The SVC was measured using spirometry (Pony FX, COSMED Inc., Italy). The intervention used was stretching of the scalene muscles. Stretching was carried out for 15 min, 10 times at per each portion of scalene muscles: the anterior, middle, and posterior parts. [Results] Expiratory vital capacity (EVC) and tidal volume (Vt) noticeably increased after stretching. However, there were no changes in any of the SVC items in the control group. [Conclusion] This study demonstrated that stretching of the scalene muscles can effectively improve SVC. In particular, we confirmed that stretching of the scalene muscles was effective in increasing EVC and Vt, which are items of SVC.

  11. Mechanical stretch influence on lifetime of dielectric elastomer films

    Science.gov (United States)

    Iannarelli, A.; Niasar, M. Ghaffarian

    2017-04-01

    Film pre-stretching is a widely adopted solution to improve dielectric strength of the DEA systems. However, to date, long term reliability of this solution has not been investigated. In this work it is explored how the dielectric elastomer lifetime is affected by film pre-stretching. The dielectric loss of soft polydimethylsiloxane (PDMS) films is studied for different stretch ratios by measuring tanδ. Additionally, time-to-breakdown was measured at DC electric stress for different stretch ratios. For this purpose, accelerated life test (ALT) were performed. The results obtained are compared with non-pre-stretched samples. This study suggests that no additional dielectric losses are caused by film stretching up to 80% of original dimensions.

  12. 2008 Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Philip J. Reid

    2009-09-21

    The conference focuses on using vibrational spectroscopy to probe structure and dynamics of molecules in gases, liquids, and interfaces. The goal is to bring together a collection of researchers who share common interests and who will gain from discussing work at the forefront of several connected areas. The intent is to emphasize the insights and understanding that studies of vibrations provide about a variety of systems.

  13. Proprioceptive neuromuscular facilitation stretching : mechanisms and clinical implications.

    Science.gov (United States)

    Sharman, Melanie J; Cresswell, Andrew G; Riek, Stephan

    2006-01-01

    Proprioceptive neuromuscular facilitation (PNF) stretching techniques are commonly used in the athletic and clinical environments to enhance both active and passive range of motion (ROM) with a view to optimising motor performance and rehabilitation. PNF stretching is positioned in the literature as the most effective stretching technique when the aim is to increase ROM, particularly in respect to short-term changes in ROM. With due consideration of the heterogeneity across the applied PNF stretching research, a summary of the findings suggests that an 'active' PNF stretching technique achieves the greatest gains in ROM, e.g. utilising a shortening contraction of the opposing muscle to place the target muscle on stretch, followed by a static contraction of the target muscle. The inclusion of a shortening contraction of the opposing muscle appears to have the greatest impact on enhancing ROM. When including a static contraction of the target muscle, this needs to be held for approximately 3 seconds at no more than 20% of a maximum voluntary contraction. The greatest changes in ROM generally occur after the first repetition and in order to achieve more lasting changes in ROM, PNF stretching needs to be performed once or twice per week. The superior changes in ROM that PNF stretching often produces compared with other stretching techniques has traditionally been attributed to autogenic and/or reciprocal inhibition, although the literature does not support this hypothesis. Instead, and in the absence of a biomechanical explanation, the contemporary view proposes that PNF stretching influences the point at which stretch is perceived or tolerated. The mechanism(s) underpinning the change in stretch perception or tolerance are not known, although pain modulation has been suggested.

  14. Low frequency torsional vibration gaps in the shaft with locally resonant structures

    International Nuclear Information System (INIS)

    Yu Dianlong; Liu Yaozong; Wang Gang; Cai Li; Qiu Jing

    2006-01-01

    The propagation of torsional wave in the shaft with periodically attached local resonators is studied with the transfer matrix theory and the finite element method. The analytical dispersion relation and the complex band structure of such a structure is presented for the first time, which indicates the existence of low frequency gaps. The effect of shaft material on the vibration attenuation in band gap is investigated. The frequency response function of the shaft with finite periodic locally resonant oscillators is simulated with finite element method, which shows large vibration attenuation in the frequency range of the gap as expected. The low frequency torsional gap in shafts provides a new idea for vibration control

  15. Calculation of Vibrational Spectra of p-Ethylbenzenesulfonic Acid Hydrates

    Science.gov (United States)

    Zelenkovskii, V. M.; Bezyazychnaya, T. V.; Soldatov, V. S.

    2013-09-01

    Quantum-chemical calculations of vibrational spectra of the sulfonated ion-exchanger model p-ethylbenzenesulfonic acid hydrated by 1-10 water molecules and its dimer were calculated by the non-empirical SCF MO LCAO method with the 6-31G(d) basis set. The calculated results were compared with experimental IR and Raman spectra of sulfonated ion exchangers. The infl uence of hydration on the vibrational frequencies of functional groups in the ion exchangers was analyzed. It was shown that the sulfonic acid was completely dissociated if three and more water molecules per functional group were present. Bands near 1130 cm-1 were due to S-O-H bending vibrations in the absence of water molecules and C-S-O-H3O combination vibrations with 3-6 water molecules per sulfonic acid.

  16. Band warping, band non-parabolicity, and Dirac points in electronic and lattice structures

    Science.gov (United States)

    Resca, Lorenzo; Mecholsky, Nicholas A.; Pegg, Ian L.

    2017-10-01

    We illustrate at a fundamental level the physical and mathematical origins of band warping and band non-parabolicity in electronic and vibrational structures. We point out a robust presence of pairs of topologically induced Dirac points in a primitive-rectangular lattice using a p-type tight-binding approximation. We analyze two-dimensional primitive-rectangular and square Bravais lattices with implications that are expected to generalize to more complex structures. Band warping is shown to arise at the onset of a singular transition to a crystal lattice with a larger symmetry group, which allows the possibility of irreducible representations of higher dimensions, hence band degeneracy, at special symmetry points in reciprocal space. Band warping is incompatible with a multi-dimensional Taylor series expansion, whereas band non-parabolicities are associated with multi-dimensional Taylor series expansions to all orders. Still band non-parabolicities may merge into band warping at the onset of a larger symmetry group. Remarkably, while still maintaining a clear connection with that merging, band non-parabolicities may produce pairs of conical intersections at relatively low-symmetry points. Apparently, such conical intersections are robustly maintained by global topology requirements, rather than any local symmetry protection. For two p-type tight-binding bands, we find such pairs of conical intersections drifting along the edges of restricted Brillouin zones of primitive-rectangular Bravais lattices as lattice constants vary relatively to each other, until these conical intersections merge into degenerate warped bands at high-symmetry points at the onset of a square lattice. The conical intersections that we found appear to have similar topological characteristics as Dirac points extensively studied in graphene and other topological insulators, even though our conical intersections have none of the symmetry complexity and protection afforded by the latter more

  17. Design for maximum band-gaps in beam structures

    DEFF Research Database (Denmark)

    Olhoff, Niels; Niu, Bin; Cheng, Gengdong

    2012-01-01

    This paper aims to extend earlier optimum design results for transversely vibrating Bernoulli-Euler beams by determining new optimum band-gap beam structures for (i) different combinations of classical boundary conditions, (ii) much larger values of the orders n and n-1 of adjacent upper and lowe...

  18. Rotational bands in the quadrupole-octupole collective model

    Science.gov (United States)

    Dobrowolski, A.; Mazurek, K.; Góźdź, A.

    2018-02-01

    A collective band of positive as well as negative parity could be composed of vibrational and rotational motions. The octupole vibrational configurations can be based either on axial or nonaxial octupole excitations. A consistent approach to the quadrupole-octupole collective vibrations coupled with the rotational motion enables us to distinguish between various scenarios of disappearance of the E 2 transitions in negative-parity bands observed in several nuclei. The theoretical estimates presented here are compared with the very recent experimental energies and transition probabilities in and between the ground-state and low-energy negative-parity bands in 156Dy. A realistic collective Hamiltonian contains the potential-energy term obtained through the macroscopic-microscopic Strutinsky-like method with a particle-number-projected BCS approach and a deformation-dependent mass tensor. The potential energy and the inertia parameters are defined in the vibrational-rotational, nine-dimensional collective space of the multipole-deformation parameters and Euler angles. The symmetrization procedure applied to the eigenstates of the collective Hamiltonian ensures their uniqueness with respect to the laboratory coordinate system. This quadrupole-octupole collective approach may also allow us to find and/or verify some fingerprints of possible high-rank symmetries (e.g., tetrahedral, octahedral, ...) in nuclear collective bands.

  19. Correlation between structure and conductivity in stretched Nafion

    Science.gov (United States)

    Allahyarov, Elshad; Taylor, Philip

    2008-03-01

    We have used coarse-grained simulation methods to investigate the effect of stretching-induced structure orientation on the proton conductivity of Nafion-like polyelectrolyte membranes. Recent experimental data on the morphology of ionomers describe Nafion as an aggregation of polymeric backbone chains forming elongated objects embedded in a continuous ionic medium. Uniaxial stretching of a recast Nafion film causes a preferential orientation of these objects in the direction of stretching. Our simulations of humid Nafion show that this has a strong effect on the proton conductivity, which is enhanced along the stretching direction, while the conductivity perpendicular to the stretched polymer backbone is strongly reduced. Stretching also causes the perfluorinated side chains to orient perpendicular to the stretching axis. The sulphonate multiplets shrink in diameter as the stretching is increased and show a spatially periodic ordering in their distribution. This in turn affects the distribution of contained water at low water contents. The water forms a continuous network with narrow bridges between small water clusters absorbed in head-group multiplets. We find the morphological changes in the stretched Nafion to be retained upon removal of the uniaxial stress.

  20. Detection of Indistinct Fe-N Stretching Bands in Iron(V) Nitrides by Photodissociation Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Andris, E.; Navrátil, R.; Jašík, J.; Sabenya, G.; Costas, M.; Srnec, Martin; Roithová, J.

    2018-01-01

    Roč. 24, č. 20 (2018), s. 5078-5081 ISSN 1521-3765 R&D Projects: GA ČR(CZ) GJ15-10279Y Institutional support: RVO:61388955 Keywords : photodissociation spectrochemistry * infrared spectra * DFT Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  1. Analysis of changes of vibrational properties of water in the presence of disaccharides

    CERN Document Server

    Branca, C; Maisano, G; Migliardo, F; Romeo, G; Bennington, S M; Fak, B; Bellocco, E; Lagana', G

    2002-01-01

    Results of inelastic neutron scattering (INS) measurements performed by the MARI spectrometer (ISIS, UK) on aqueous solutions of sucrose and alpha,alpha-trehalose are reported. To get some insight into the effects of disaccharides on the hydrogen-bond network of water, we investigated the intramolecular O-H stretching modes. The obtained spectra show that, contrary to sucrose, the presence of trehalose affects significantly the pure-water O-H stretching mode. The observed changes can be related to the presence of heavier vibrating units, namely to the higher hydration number of trehalose with respect to sucrose. (orig.)

  2. Reinnervation of Paralyzed Muscle by Nerve Muscle Endplate Band Grafting

    Science.gov (United States)

    2016-10-01

    x 3 mm), a nerve branch, intramuscular nerve terminals, and a motor endplate (MEP) band with numerous neuromuscular junctions. The superficial ...when muscle was stretched at optimal tension of 0.8 N. Maximal muscle force was calculated as average muscle contraction to 5 stimulation currents...force during the 200-millisecond contraction was identified, as well as initial passive tension before stimulation. The difference between themaximal

  3. Investigation of chiral bands in {sup 106}Ag

    Energy Technology Data Exchange (ETDEWEB)

    Lieder, Evgenia [Themba LABS, Somerset West (South Africa); FhG, INT, Euskirchen (Germany); Lieder, Rainer; Bark, Rob; Lawrie, Elena; Lawrie, Kobus; Ntshangase, Sifiso; Mullins, Simon; Papka, Paul; Kheswa, Ntombi [Themba LABS, Somerset West (South Africa); Meng, Jie [PhS, PKU, Beijing (China); PhS, BUAA, Beijing (China); Qi, Bin [SDU, Weihai (China); Zhang, Shuangquan; Li, Zhipan [PhS, PKU, Beijing (China)

    2010-07-01

    Dipole bands in {sup 106}Ag have been studied with the {gamma}-detector array AFRODITE at iThemba LABS, South Africa. A {sup 96}Zr({sup 14}N,4n){sup 106}Ag reaction at a beam energy of 71 MeV has been used. The three previously known negative-parity bands in {sup 106}Ag have been extended. Bands 1 and 2 were proposed to be chiral partner bands. However, in view of the present results, bands 2 and 3 seem to be better candidates for chiral partner bands since their staggering parameters, B(M1)/B(E2) ratios, kinematic moments of inertia and quasiparticle alignments agree much better than those of bands 1 and 2. Triaxial relativistic mean field (RMF) and particle-rotor model (PRM) calculations support this interpretation. In the potential energy surface of {sup 106}Ag, obtained in RMF calculations, two minima have been found in the {beta}{sub 2}-{gamma} plane. Based on PRM calculations using the deformation parameters of the two minima and a {nu}h{sub 11/2} x {pi}g{sup -1}{sub 9/2} particle-hole configuration, bands 2 and 3 may represent partners with chiral vibration at {gamma}{approx}12degree. Band 1, located in the other minimum, may be a magnetic dipole band or the partner of a second pair of chiral bands.

  4. Full dimensional (15-dimensional) quantum-dynamical simulation of the protonated water dimer. II. Infrared spectrum and vibrational dynamics

    DEFF Research Database (Denmark)

    Vendrell, Oriol; Gatti, Fabien; Meyer, Hans-Dieter

    2007-01-01

    the fundamentals and several overtones of the vibrational motion are computed. The spectrum of H5O2+ is shaped to a large extent by couplings of the proton-transfer motion to large amplitude fluxional motions of the water molecules, water bending and water-water stretch motions. These couplings are identified...

  5. Interaction of spin and vibrations in transport through single-molecule magnets.

    Science.gov (United States)

    May, Falk; Wegewijs, Maarten R; Hofstetter, Walter

    2011-01-01

    We study electron transport through a single-molecule magnet (SMM) and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST) and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands.

  6. Interaction of spin and vibrations in transport through single-molecule magnets

    Directory of Open Access Journals (Sweden)

    Falk May

    2011-10-01

    Full Text Available We study electron transport through a single-molecule magnet (SMM and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands.

  7. Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship

    DEFF Research Database (Denmark)

    Balle, S S; Magnusson, S P; McHugh, M P

    2015-01-01

    The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength...... loss compared with SS. These results support the use of SS for stretching the hamstrings....

  8. EFFECTIVENESS OF PNF STRETCHING VERSUS STATIC STRETCHING ON PAIN AND HAMSTRING FLEXIBILITY FOLLOWING MOIST HEAT IN INDIVIDUALS WITH KNEE OSTEOARTHRITIS

    Directory of Open Access Journals (Sweden)

    Meena .V

    2016-10-01

    Full Text Available Background: Osteoarthritis (OA is a degenerative joint disease and one of the major public health problem that causesfunctional impairment and reduced quality of life. To compare the effectiveness of PNF Hold relax stretching versus Static stretching on pain and flexibility of hamstring following moist heat in individuals with knee osteoarthritis. Hamstring tightness is the major problem in knee osteoarthritis individuals. Therefore the need of study is comparing the effectiveness of PNF Hold relax stretching versus static stretching on pain and flexibility of hamstrings following moist heat in knee osteoarthritis participants. Determining the effects of PNF Hold relax stretching versus Static stretching along with moist heat on pain and hamstring flexibility by VAS and Active knee extension range of motion in knee osteoarthritis individuals. Methods: 30 subjects with symptoms of knee osteoarthritis were randomly distributed into 2 groups 15 in each group. PNF Hold relax stretching along with moist heat is compared to Static stretching along with moist heat. Pain was measured by Visual Analogue Scale (VAS and hamstring flexibility by Active knee Extension Range of Motion (AKEROM by universal goniometer. Measurements are taken pre and post intervention. Results: The results indicated PNF Hold relax stretching along with moist heat showed a statistically significant improvement in pain (p<0.05 and improvement in hamstring flexibility (p<0.05 when compared to Static stretching along with moist heat. Conclusion: Subjects with PNF Hold relax stretching along with moist heat showed significant improvement in pain reduction and improving hamstring flexibility than Static stretching along with moist heat.

  9. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects

    OpenAIRE

    O'Sullivan, Kieran; Murray, Elaine; Sainsbury, David

    2009-01-01

    Abstract Background Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. Methods A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured indi...

  10. Sweeping shunted electro-magnetic tuneable vibration absorber: Design and implementation

    Science.gov (United States)

    Turco, E.; Gardonio, P.

    2017-10-01

    This paper presents a study on the design and implementation of a time-varying shunted electro-magnetic Tuneable Vibration Absorber for broad-band vibration control of thin structures. A time-varying RL-shunt is used to harmonically vary the stiffness and damping properties of the Tuneable Vibration Absorber so that its mechanical fundamental natural frequency is continuously swept in a given broad frequency band whereas its mechanical damping is continuously adapted to maximize the vibration absorption from the hosting structure where it is mounted. The paper first recalls the tuning and positioning criteria for the case where a classical Tuneable Vibration Absorber is installed on a thin walled cylindrical structure to reduce the response of a resonating flexural mode. It then discusses the design of the time-varying shunt circuit to produce the desired stiffness and damping variations in the electro-magnetic Tuneable Vibration Absorber. Finally, it presents a numerical study on the flexural vibration and interior sound control effects produced when an array of these shunted electro-magnetic Tuneable Vibration Absorbers are mounted on a thin walled cylinder subject to a rain-on-the-roof stochastic excitation. The study shows that the array of proposed systems effectively controls the cylinder flexural response and interior noise over a broad frequency band without need of tuning and thus system identification of the structure. Therefore, the systems can be successfully used also on structures whose physical properties vary in time because of temperature changes or tensioning effects for example.

  11. LABOR GYMNASTICS: STRETCHING EXERCISE X FLEXIONAMENT

    Directory of Open Access Journals (Sweden)

    Jacqueline Amorin Anchieta Borges da Silva, Isabel Cristina Taranto e Fernanda Piasecki

    2006-12-01

    Full Text Available Nowadays, there are many opportunities for the society to live a healthful and long life. At the same time, never people was so sedentary and without harmony. Without a healthy body and with “an occupied mind” the human loses exactly what more it needs: the disposal to produce, to coexist and to live a good life. In this context, the present research aimed to revise some terms related to labor gymnastics, which is focused in the prevention of risks related to hours of working and in the reduction of muscular tension levels that may be originated during a day of work. Thus, the present study will make a differentiation between the use of stretching and flexionament during labor gymnastic sessions.

  12. Stretched Lens Array Photovoltaic Concentrator Technology Developed

    Science.gov (United States)

    Piszczor, Michael F., Jr.; O'Neill, Mark J.

    2004-01-01

    Solar arrays have been and continue to be the mainstay in providing power to nearly all commercial and government spacecraft. Light from the Sun is directly converted into electrical energy using solar cells. One way to reduce the cost of future space power systems is by minimizing the size and number of expensive solar cells by focusing the sunlight onto smaller cells using concentrator optics. The stretched lens array (SLA) is a unique concept that uses arched Fresnel lens concentrators to focus sunlight onto a line of high-efficiency solar cells located directly beneath. The SLA concept is based on the Solar Concentrator Array with Refractive Linear Element Technology (SCARLET) design that was used on NASA's New Millennium Deep Space 1 mission. The highly successful asteroid/comet rendezvous mission (1998 to 2001) demonstrated the performance and long-term durability of the SCARLET/SLA solar array design and set the foundation for further improvements to optimize its performance.

  13. Aerothermodynamic properties of stretched flames in enclosures

    Science.gov (United States)

    Rotman, D. A.; Oppenheim, A. K.

    Flames are stretched by being pulled along their frontal surface by the flow field in which they reside. Their trajectories tend to approach particle paths, acquiring eventually the role of contact boundaries, -interfaces between the burnt and unburnt medium that may broaden solely as a consequence of diffusion. Fundamental properties of flow fields governing such flames are determined here on the basis of the zero Mach number model, providng a rational method of approach to the computational analysis of combustion fields in enclosures where, besides the aerodynamic properties flow, the thermodynamic process of compression must be taken into account. To illustrate its application, the method is used to reveal the mechanism of formation of a tulip-shape flame in a rectangular enclosure under nonturbulent flow conditions.

  14. Vibrational Investigations of Silver-Doped Hydroxyapatite with Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    Carmen Steluta Ciobanu

    2013-01-01

    Full Text Available Silver-doped hydroxyapatite (Ag:HAp was obtained by coprecipitation method. Transmission electron microscopy (TEM, infrared, and Raman analysis confirmed the development of Ag:HAp with good crystal structure. Transmission electron microscopy analysis showed an uniform ellipsoidal morphology with particles from 5 nm to 15 nm. The main vibrational bands characteristic to HAp were identified. The bands assigned to phosphate vibrational group were highlighted in infrared and Raman spectra. The most intense peak Raman spectrum is the narrow band observed at 960 cm−1. In this article Ag:HAp-NPs were also evaluated for their antimicrobial activities against gram-positive, gram-negative, and fungal strains. The specific antimicrobial activity revealed by the qualitative assay demonstrates that our compounds are interacting differently with the microbial targets.

  15. Vibrational tug-of-war: The pKA dependence of the broad vibrational features of strongly hydrogen-bonded carboxylic acids

    Science.gov (United States)

    Van Hoozen, Brian L.; Petersen, Poul B.

    2018-04-01

    Medium and strong hydrogen bonds give rise to broad vibrational features frequently spanning several hundred wavenumbers and oftentimes exhibiting unusual substructures. These broad vibrational features can be modeled from first principles, in a reduced dimensional calculation, that adiabatically separates low-frequency modes, which modulate the hydrogen bond length, from high-frequency OH stretch and bend modes that contribute to the vibrational structure. Previously this method was used to investigate the origin of an unusual vibrational feature frequently found in the spectra of dimers between carboxylic acids and nitrogen-containing aromatic bases that spans over 900 cm-1 and contains two broad peaks. It was found that the width of this feature largely originates from low-frequency modes modulating the hydrogen bond length and that the structure results from Fermi resonance interactions. In this report, we examine how these features change with the relative acid and base strength of the components as reflected by their aqueous pKA values. Dimers with large pKA differences are found to have features that can extend to frequencies below 1000 cm-1. The relationships between mean OH/NH frequency, aqueous pKA, and O-N distance are examined in order to obtain a more rigorous understanding of the origin and shape of the vibrational features. The mean OH/NH frequencies are found to correlate well with O-N distances. The lowest OH stretch frequencies are found in dimer geometries with O-N distances between 2.5 and 2.6 Å. At larger O-N distances, the hydrogen bonding interaction is not as strong, resulting in higher OH stretch frequencies. When the O-N distance is smaller than 2.5 Å, the limited space between the O and N determines the OH stretch frequency, which gives rise to frequencies that decrease with O-N distances. These two effects place a lower limit on the OH stretch frequency which is calculated to be near 700 cm-1. Understanding how the vibrational features

  16. Vibrational sum frequency generation spectroscopy using inverted visible pulses.

    Science.gov (United States)

    Weeraman, Champika; Mitchell, Steven A; Lausten, Rune; Johnston, Linda J; Stolow, Albert

    2010-05-24

    We present a broadband vibrational sum frequency generation (BB-VSFG) scheme using a novel ps visible pulse shape. We generate the fs IR pulse via standard procedures and simultaneously generate an 'inverted' time-asymmetric narrowband ps visible pulse via second harmonic generation in the pump depletion regime using a very long nonlinear crystal which has high group velocity mismatch (LiNbO3). The 'inverted' ps pulse shape minimally samples the instantaneous nonresonant response but maximally samples the resonant response, maintaining high spectral resolution. We experimentally demonstrate this scheme, presenting SFG spectra of canonical organic monolayer systems in the C-H stretch region (2800-3000 cm(-1)).

  17. Electroforesis of Whey and Stretching Water Protein of Mozzarella Cheese Production from Factorial Experimental of Coagulation and Stretching Temperature

    Directory of Open Access Journals (Sweden)

    Purwadi Purwadi

    2012-02-01

    Full Text Available The use of lime juice as acidifier in the making of Mozzarella cheese was aimed to learn the protein profile of whey and stretching water produced with treatment of coagulation and stretching temperature. The treatment of coagulation temperature was G1 = 30oC, G2 = 35oC, G3 = 40oC, and G4 = 45oC, and the treatment of stretching temperature was M1 = 70oC, M2 = 75oC, M3 = 80oC, and M4 = 85oC. The research result showed that coagulation temperature of 30 and 35 oC gave the same protein profile of whey as well as coagulation temperature of 40 and 45oC, while coagulation temperature of 30 and 35oC with coagulation temperatur of 40 and 45oC gave different protein profile of whey. Different coagulation temperature gave different protein profile of whey and stretching water, while different stretching temperature gave the same protein profile of stretching water. Coagulation temperature of 30 and 35oC gave the same protein profile of stretching water as well as coagulation temperature of 40 and 45oC, while coagulation temperature of 30 and 35oC with temperature of 40 and 45oC gave different protein profile of stretching water. Keywords: protein profile, Mozzarella cheese, coagulation temperature, stretching temperature

  18. EFFICACY OF MODIFIED PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION STRETCHING WITH CRYOTHERAPY OVER MANUAL PASSIVE STRETCHING WITH CRYOTHERAPY ON HAMSTRING FLEXIBILITY

    Directory of Open Access Journals (Sweden)

    Shamik Bhattacharjee

    2016-04-01

    Full Text Available Background: Healthy individuals, to ease and accomplish their activities of daily living they need flexible body without any tightness in the muscles, particularly those used for a definite function. Cooling soft tissues in a lengthened position after stretching has been shown to promote more lasting increases in soft tissue length and minimize post stretch muscle soreness. There are less documented studies which compared modified proprioceptive neuromuscular facilitation (PNF stretch over passive manual stretch with cold application commonly after the interventions. Methods: Thirty high school going healthy students were divided into two groups- Group I received Passive Manual stretching (n=15 and Group II received modified PNF stretching (n=15 and both groups received cold application after the interventions for 10 minutes commonly for 5 days. ROM was taken on day 1, day 5 and day 7. Results: After day 7, Group II with Modified PNF stretching along with cold application showed a significant increase in range of motion tested with active knee extension test (AKET. Conclusion: Modified PNF stretching is considered to be the effective intervention in increasing and maintaining ROM in AKET over passive manual stretching with cold applications commonly after the interventions.

  19. Immediate Effects of Proprioceptive Neuromuscular Facilitation Stretching Programs Compared With Passive Stretching Programs for Hamstring Flexibility: A Critically Appraised Topic.

    Science.gov (United States)

    Hill, Kristian J; Robinson, Kendall P; Cuchna, Jennifer W; Hoch, Matthew C

    2017-11-01

    Clinical Scenario: Increasing hamstring flexibility through clinical stretching interventions may be an effective means to prevent hamstring injuries. However the most effective method to increase hamstring flexibility has yet to be determined. For a healthy individual, are proprioceptive neuromuscular facilitation (PNF) stretching programs more effective in immediately improving hamstring flexibility when compared with static stretching programs? Summary of Key Findings: A thorough literature search returned 195 possible studies; 5 studies met the inclusion criteria and were included. Current evidence supports the use of PNF stretching or static stretching programs for increasing hamstring flexibility. However, neither program demonstrated superior effectiveness when examining immediate increases in hamstring flexibility. Clinical Bottom Line: There were consistent findings from multiple low-quality studies that indicate there is no difference in the immediate improvements in hamstring flexibility when comparing PNF stretching programs to static stretching programs in physically active adults. Strength of Recommendation: Grade B evidence exists that PNF and static stretching programs equally increase hamstring flexibility immediately following the stretching program.

  20. Effect of Spindle Parameters of Woodworking Band Saw on the AE Value of Crack Band Saw Blade in Compound Material Processing (1)

    Science.gov (United States)

    Gao, Jin-gui; Jiang, Zhao-fang; Luo, Lai-peng

    2017-04-01

    Taking the MJ3210A motion band saw as the research object, the AE value of the band saw blade vibration was obtained by analyzing the VIBSYS vibration signal acquisition and analysis software system in Beijing, and the change of the AE value of the band saw and the crack was found out. The experimental results show that in the MJ3210A sports car sawing machine, the band saw blade with width of 130 mm is used, and the AE value of the cracked band saw blade is well in the high band saw blade AE value. Under the best working condition of the band saw, the band saw blade AE If the value exceeds 104.7 dB (A) above, it means that the band saw blade has at least one crack length greater than 1.38 mm for the crack defect and the need to replace the band saw blade in time. Different species with saw blade of the AE value is different, white pine wood minimum, the largest oak wood; according to a variety of wood processing AE instrument value to determine the band saw blade crack to the situation; so as to fully rational use of band saw blade, The failure and the degree of development to find a new method.

  1. Vibration transducer calibration techniques

    Science.gov (United States)

    Brinkley, D. J.

    1980-09-01

    Techniques for the calibration of vibration transducers used in the Aeronautical Quality Assurance Directorate of the British Ministry of Defence are presented. Following a review of the types of measurements necessary in the calibration of vibration transducers, the performance requirements of vibration transducers, which can be used to measure acceleration, velocity or vibration amplitude, are discussed, with particular attention given to the piezoelectric accelerometer. Techniques for the accurate measurement of sinusoidal vibration amplitude in reference-grade transducers are then considered, including the use of a position sensitive photocell and the use of a Michelson laser interferometer. Means of comparing the output of working-grade accelerometers with that of previously calibrated reference-grade devices are then outlined, with attention given to a method employing a capacitance bridge technique and a method to be used at temperatures between -50 and 200 C. Automatic calibration procedures developed to speed up the calibration process are outlined, and future possible extensions of system software are indicated.

  2. Spectroscopic investigation of the vibrational quasi-continuum arising from internal rotation of a methyl group

    Energy Technology Data Exchange (ETDEWEB)

    Hougen, J.T. [NIST, Gaithersburg, MD (United States)

    1993-12-01

    The goal of this project is to use spectroscopic techniques to investigate in detail phenomena involving the vibrational quasi-continuum in a simple physical system. Acetaldehyde was chosen for the study because: (i) methyl groups have been suggested to be important promotors of intramolecular vibrational relaxation, (ii) the internal rotation of a methyl group is an easily describle large-amplitude motion, which should retain its simple character even at high levels of excitation, and (iii) the aldehyde carbonyl group offers the possibility of both vibrational and electronic probing. The present investigation of the ground electronic state has three parts: (1) understanding the {open_quotes}isolated{close_quotes} internal-rotation motion below, at, and above the top of the torsional barrier, (2) understanding in detail traditional (bond stretching and bending) vibrational fundamental and overtone states, and (3) understanding interactions involving states with multiquantum excitations of at least one of these two kinds of motion.

  3. Spins, Parity, Excitation Energies, and Octupole Structure of an Excited Superdeformed Band in 194Hg and Implications for Identical Bands

    Science.gov (United States)

    Hackman, G.; Khoo, T. L.; Carpenter, M. P.; Lauritsen, T.; Lopez-Martens, A.; Calderin, I. J.; Janssens, R. V.; Ackermann, D.; Ahmad, I.; Agarwala, S.; Blumenthal, D. J.; Fischer, S. M.; Nisius, D.; Reiter, P.; Young, J.; Amro, H.; Moore, E. F.; Hannachi, F.; Korichi, A.; Lee, I. Y.; Macchiavelli, A. O.; Døssing, T.; Nakatsukasa, T.

    1997-11-01

    An excited superdeformed band in 194Hg, observed to decay directly to both normal-deformed and superdeformed yrast states, is proposed to be a Kπ = 2- octupole vibrational band, based on its excitation energies, spins, and likely parity. The transition energies are identical to those of the yrast superdeformed band in 192Hg, but originate from levels with different spins and parities. The evolution of transition energies with spin suggests that cancellations between pairing and particle alignment are partly responsible for the identical transition energies.

  4. Theoretical and experimental investigations of thickness- stretch modes in 1-3 piezoelectric composites

    International Nuclear Information System (INIS)

    Yang, Z T; Zeng, D P; He, M; Wang, H

    2015-01-01

    Bulk piezoelectric ceramics operating in thickness-stretch (TSt) modes have been widely used in acoustic-related devices. However, the fundamental TSt waves are always coupled with other modes, and the occurrence of these spurious modes in bulk piezoelectric ceramics affects its performance. To suppress the spurious modes, 1-3 piezoelectric composites are promising candidates. However, theoretical modeling of multiphase ceramic composite objects is very complex. In this study, a 1-3 piezoelectric composite sample and a bulk piezoelectric sample are fabricated. The electrical impedance of these two samples are compared. A simple analytical TSt vibration mode from the three dimensional equations of linear piezoelectricity is used to model the performance of 1-3 piezoelectric composites. The theoretical results agree well with the experimental results. (paper)

  5. Thermal expansivity of highly-stretched linear polyethylene with extended chains irradiated with different doses of γ-rays

    International Nuclear Information System (INIS)

    Turetskij, A.A.; Chvalun, S.N.; Zubov, Yu.A.; Bakeev, N.F.

    1993-01-01

    Temperature begavior of crystal lattice parameters of highly-stretched samples of linear polyethylene with extended chains irradiated with different doses of γ-rays was studied. It was found that transverse vibrations of macromolecular chains are excited at irradiation doses D≥500 Mrad and temperatures close to the melting temperature of the crystallites. These vibrations cause a sharp increase in the latiice parameter a. But no phase transition to the hexagonal packing occurs. It was shown that the thermal expansivity of the lattice parameter c changes its sign at high irradiation doses. These results are explained by the presence in the crystallites of samples irradiated with large doses of a considerable number of intermolecular chemical bonds

  6. Optimum design of band-gap beam structures

    DEFF Research Database (Denmark)

    Olhoff, Niels; Niu, Bin; Cheng, Gengdong

    2012-01-01

    in the present paper that such an a priori assumption is not necessary since, in general, just the maximization of the gap between two consecutive natural frequencies leads to significant design periodicity. The aim of this paper is to maximize frequency gaps by shape optimization of transversely vibrating......The design of band-gap structures receives increasing attention for many applications in mitigation of undesirable vibration and noise emission levels. A band-gap structure usually consists of a periodic distribution of elastic materials or segments, where the propagation of waves is impeded...... or significantly suppressed for a range of external excitation frequencies. Maximization of the band-gap is therefore an obvious objective for optimum design. This problem is sometimes formulated by optimizing a parameterized design model which assumes multiple periodicity in the design. However, it is shown...

  7. Effects of acute stretching on the maximal expression of strength ...

    African Journals Online (AJOL)

    This study compared the effects of four treatments (n = 12 each) [10 minutes of quiet sitting, without stretching (NS); two minutes warm up on an arm ergometer at 25 watts resistance (WU); 10 second-hold static stretching (each) of the shoulder, chest and arm muscle groups (ST10); and two sets of 20 second-hold static ...

  8. The stretch reflex and the contributions of C David Marsden.

    Science.gov (United States)

    Bhattacharyya, Kalyan B

    2017-01-01

    The stretch reflex or myotatic reflex refers to the contraction of a muscle in response to its passive stretching by increasing its contractility as long as the stretch is within physiological limits. For ages, it was thought that the stretch reflex was of short latency and it was synonymous with the tendon reflex, subserving the same spinal reflex arc. However, disparities in the status of the two reflexes in certain clinical situations led Marsden and his collaborators to carry out a series of experiments that helped to establish that the two reflexes had different pathways. That the two reflexes are dissociated has been proved by the fact that the stretch reflex and the tendon reflex, elicited by stimulation of the same muscle, have different latencies, that of the stretch reflex being considerably longer. They hypothesized that the stretch reflex had a transcortical course before it reached the spinal motor neurons for final firing. Additionally, the phenomenon of stimulus-sensitive cortical myoclonus lent further evidence to the presence of the transcortical loop where the EEG correlate preceded the EMG discharge. This concept has been worked out by later neurologists in great detail, and the general consensus is that indeed, the stretch reflex is endowed with a conspicuous transcortical component.

  9. Chaperones in Polyglutamine Aggregation : Beyond the Q-Stretch

    NARCIS (Netherlands)

    Kuiper, E. F. E.; de Mattos, Eduardo P.; Jardim, Laura B.; Kampinga, Harm H.; Bergink, Steven

    2017-01-01

    Expanded polyglutamine (polyQ) stretches in at least nine unrelated proteins lead to inherited neuronal dysfunction and degeneration. The expansion size in all diseases correlates with age at onset (AO) of disease and with polyQ protein aggregation, indicating that the expanded polyQ stretch is the

  10. Stretched exponential relaxation and ac universality in disordered dielectrics

    DEFF Research Database (Denmark)

    Milovanov, Alexander V.; Rypdal, Kristoffer; Juul Rasmussen, Jens

    2007-01-01

    are stretched exponential character of dielectric relaxation, power-law power spectral density, and anomalous dependence of ac conduction coefficient on frequency. We propose a self-consistent model of dielectric relaxation in which the relaxations are described by a stretched exponential decay function...

  11. Time and direction preparation of the long latency stretch reflex.

    Science.gov (United States)

    Nikaido, Yasutaka; Hatanaka, Ryota; Jono, Yasutomo; Nomura, Yoshifumi; Tani, Keisuke; Chujo, Yuta; Hiraoka, Koichi

    2016-06-01

    This study investigated time and direction preparation of motor response to force load while intending to maintain the finger at the initial neutral position. Force load extending or flexing the index finger was given while healthy humans intended to maintain the index finger at the initial neutral position. Electromyographic activity was recorded from the first dorsal interosseous muscle. A precue with or without advanced information regarding the direction of the forthcoming force load was given 1000ms before force load. Trials without the precue were inserted between the precued trials. A long latency stretch reflex was elicited by force load regardless of its direction, indicating that the long latency stretch reflex is elicited not only by muscle stretch afferents, but also by direction-insensitive sensations. Time preparation of motor response to either direction of force load enhanced the long latency stretch reflex, indicating that time preparation is not mediated by afferent discharge of muscle stretch. Direction preparation enhanced the long latency stretch reflex and increased corticospinal excitability 0-20ms after force load when force load was given in the direction stretching the muscle. These enhancements must be induced by preset of the afferent pathway mediating segmental stretch reflex. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. The stretch reflex and the contributions of C David Marsden

    Directory of Open Access Journals (Sweden)

    Kalyan B Bhattacharyya

    2017-01-01

    Full Text Available The stretch reflex or myotatic reflex refers to the contraction of a muscle in response to its passive stretching by increasing its contractility as long as the stretch is within physiological limits. For ages, it was thought that the stretch reflex was of short latency and it was synonymous with the tendon reflex, subserving the same spinal reflex arc. However, disparities in the status of the two reflexes in certain clinical situations led Marsden and his collaborators to carry out a series of experiments that helped to establish that the two reflexes had different pathways. That the two reflexes are dissociated has been proved by the fact that the stretch reflex and the tendon reflex, elicited by stimulation of the same muscle, have different latencies, that of the stretch reflex being considerably longer. They hypothesized that the stretch reflex had a transcortical course before it reached the spinal motor neurons for final firing. Additionally, the phenomenon of stimulus-sensitive cortical myoclonus lent further evidence to the presence of the transcortical loop where the EEG correlate preceded the EMG discharge. This concept has been worked out by later neurologists in great detail , and the general consensus is that indeed, the stretch reflex is endowed with a conspicuous transcortical component.

  13. Transparent conducting film: Effect of mechanical stretching to ...

    Indian Academy of Sciences (India)

    We describe in this paper a transparent conducting film (TCF). It is a fibrous layer of multiwalled carbon nanotubes (MWNTs), labeled a dilute CNT mat, that was prepared and unidirectionally stretched to improve both the optical and electrical properties. After stretching by 80% strain, transmittance at 550 nm wavelength ...

  14. The effects of acute self myofascial release (MFR) and stretching ...

    African Journals Online (AJOL)

    Baseline measurements were taken initially and then participants were randomly divided into four groups (control [n=10, static stretching [n=10], dynamic stretching [n=10] and self MFR [n=10]). Each group performed a 60-minute intervention. During the intervention programme the various groups took part in prescribed ...

  15. Transparent conducting film: Effect of mechanical stretching to ...

    Indian Academy of Sciences (India)

    Administrator

    The number of pixels inside a rectangle counted on the Adobe Photoshop. Figure 6. Sheet resistance and transmittance at 550 nm wave- length of a dilute CNT mat before and after stretch. Five sam- ples were stretched by 40 and 110% strain respectively and average data is shown in each case. A polyurethane elastomer.

  16. Does Postexercise Static Stretching Alleviate Delayed Muscle Soreness?

    Science.gov (United States)

    Buroker, Katherine C.; Schwane, James A.

    1989-01-01

    Because many experts recommend stretching after exercise to relieve muscle soreness, 23 subjects performed a 30-minute step test to induce delayed muscle soreness. There was neither temporary relief of pain immediately after stretching nor a reduction in pain during the 3-day postexercise period. (Author/SM)

  17. Mechanical stretch influence on lifetime of dielectric elastomer films

    NARCIS (Netherlands)

    Iannarelli, A.; Ghaffarian Niasar, M.; Bar-Cohen, Yoseph

    2017-01-01

    Film pre-stretching is a widely adopted solution to improve dielectric strength of the DEA systems. However, to date, long term reliability of this solution has not been investigated. In this work it is explored how the dielectric elastomer lifetime is affected by film pre-stretching. The dielectric

  18. Vibration-related extrusion of capillary blood from the calf musculature depends upon directions of vibration of the leg and of the gravity vector.

    Science.gov (United States)

    Çakar, Halil Ibrahim; Doğan, Serfiraz; Kara, Sadık; Rittweger, Jörn; Rawer, Rainer; Zange, Jochen

    2017-06-01

    In this study, we investigated the effects of vibration of the whole lower leg on the content and the oxygenation of hemoglobin in the unloaded relaxed lateral gastrocnemius muscle. Vibration was applied orthogonal to and in parallel with leg axis to examine whether the extrusion of blood depends on an alignment of main vessel direction, axis of vibration and gravity. The blood volume in the muscles was altered by horizontal and 30° upright body posture. Fifteen male subjects were exposed to 4 sets of experiments with both vibration directions and both tilt angles applied in permutated order. The absence of voluntary muscular activity and the potential occurrence of compound action potentials by stretch reflexes were monitored using electromyography. Total hemoglobin and tissue saturation index were measured with near infrared spectroscopy. Changes of lower leg circumference were measured with strain gauge system placed around the calf. Vibration caused decrease in tHb and increase in TSI indicating extrusion of predominantly venous blood from the muscle. In 30° tilted position, muscles contained more blood at baseline and vibration ejected more blood from the muscle compared with horizontal posture (p < 0.01). At 30° tilting deeper drop in tHb and steeper increase in TSI (p < 0.01) were observed when vibration was applied in parallel with the length axis of muscle. It is concluded that the vibration extrudes more blood in 30° head up posture and the vibration applied in parallel with the length axis of the muscle is more effective than orthogonal vibration.

  19. The effect of calf stretching box on stretching calf muscle compliance: a prospective, randomized single-blinded controlled trial.

    Science.gov (United States)

    Chadchavalpanichaya, Navaporn; Srisawasdi, Gulapar; Suwannakin, Atchara

    2010-12-01

    To study the effect of calf stretching box usage in increasing the compliance of performing calf stretching exercise as compared to the conventional exercise method. To study the effect of calf stretching box usage in decreasing the calf muscle tightness and complications as compared to the conventional exercise method. Eighty patients older than 45 years old with calf muscles tightness were enrolled in a prospective, randomized single-blinded controlled trial at the out-patient Rehabilitation medicine clinic, Siriraj Hospital, Bangkok Thailand between April and August 2009. Patients were randomized into two groups, the study group (stretching by using calf stretching box) and the control group (stretching by the conventional exercise method). Patients in both groups were asked to hold the stretch for at least 1 minute and to perform the stretching program at least two times per day, every day for two weeks. Furthermore, they were asked to record the real frequency and duration of their exercise and complications in a logbook every day. Thirty-eight patients in each group completed the study. The baseline characteristics of the patients in both groups were similar. The study group had higher frequency and longer duration of performing calf stretching exercise than the control group. They also reported more decrease of calf muscle tightness with less pain complication (shoulder pain, knee pain, low back pain, and calf muscle pain) than the control group (p calf muscle and degree of ankle range of motion between the two groups. Stretching calf muscle with calf stretching box can increase compliance, decrease calf muscle tightness and decrease complications when compared with the conventional exercise method.

  20. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects.

    Science.gov (United States)

    O'Sullivan, Kieran; Murray, Elaine; Sainsbury, David

    2009-04-16

    Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. Across both groups, there was a significant main effect for time (p static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05). Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes. ACTRN12608000638336.

  1. Vibrations in orthopedics.

    Science.gov (United States)

    Nokes, L D; Thorne, G C

    1988-01-01

    Measurements of various mechanical properties of skeletal material using vibration techniques have been reported. The purposes of such investigations include the monitoring of pathogenic disorders such as osteoporosis, the rate and extent of fracture healing, and the status of internal fixations. Early investigations pioneered the application of conventional vibration measurement equipment to biological systems. The more recent advent of the microcomputer has made available to research groups more sophisticated techniques for data acquisition and analysis. The economical advantages of such equipment has led to the development of portable research instrumentation which lends itself to use in a clinical environment. This review article reports on the developments and progression of the various vibrational techniques and theories as applied to musculoskeletal systems.

  2. O corpo do cantor: alongar, relaxar ou aquecer? The singer's body: stretch, relax or warm-up?

    Directory of Open Access Journals (Sweden)

    Enio Lopes Mello

    2008-12-01

    Full Text Available TEMA: exercícios físicos e canto. OBJETIVO: fazer uma reflexão a respeito da diferença entre: alongamento, relaxamento e aquecimento e seus benefícios para os cantores. CONCLUSÃO: exercícios de aquecimento e alongamento são complementares na preparação de cantores. Aquecimento previne lesões, favorece o alongamento e garante melhor vibração das pregas vocais. Alongamento auxilia na manutenção da postura e na abertura do tórax. Relaxamento é desaconselhado na preparação do canto, porque pode comprometer o controle motor. Vocalizar é um excelente exercício de aquecimento e de alongamento das pregas vocais, porém deve ser antecedido pelo aquecimento do corpo, com ênfase na musculatura extrínseca e intrínseca da laringe sem emissão sonora.BACKGROUND: physical exercises and singing. PURPOSE: to make a reflection on the difference among stretching, relaxation and warm-up and theirs benefits for singers. CONCLUSION: warm-up and stretching exercises are complementary to preparation of singers. Warm-up prevents injuries; is favorable for stretching and provides us with better vocal folds vibration. The stretching aids to maintain posture and opening the thorax. The relaxation is not advisable to prepare the singing, because it may compromise the motor control. Vocalize is an excellent exercise for warm-up and stretching as for the vocal folds, but it must come anteceded by body warm-up, with emphasis on the extrinsic and intrinsic muscles of the larynx, without sound emission.

  3. Stretch reflex regulation in healthy subjects and patients with spasticity

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Petersen, Nicolas; Crone, Clarissa

    2005-01-01

    In recent years, part of the muscle resistance in spastic patients has been explained by changes in the elastic properties of muscles. However, the adaptive spinal mechanisms responsible for the exaggeration of stretch reflex activity also contribute to muscle stiffness. The available data suggest...... of the spastic symptoms. A recent finding also shows no sign of exaggerated stretch reflexes in muscles voluntarily activated by the spastic patient in general. This is easily explained by the control of stretch reflex activity in healthy subjects. In healthy subjects, the stretch reflex activity is increased...... movements, antagonist muscles should remain silent and maximally relaxed. This is ensured by increasing transmission in several spinal inhibitory pathways. In spastic patients, this control is inadequate, and therefore stretch reflexes in antagonist muscles are easily evoked at the beginning of voluntary...

  4. Bruxism: Is There an Indication for Muscle-Stretching Exercises?

    Science.gov (United States)

    Gouw, Simone; de Wijer, Anton; Creugers, Nico Hj; Kalaykova, Stanimira I

    Bruxism is a common phenomenon involving repetitive activation of the masticatory muscles. Muscle-stretching exercises are a recommended part of several international guidelines for musculoskeletal disorders and may be effective in management of the jaw muscle activity that gives rise to bruxism. However, most studies of muscle-stretching exercises have mainly focused on their influence on performance (eg, range of motion, coordination, and muscle strength) of the limb or trunk muscles of healthy individuals or individuals with sports-related injuries. Very few have investigated stretching of the human masticatory muscles and none muscle-stretching exercises in the management of (sleep) bruxism. This article reviews the literature on muscle-stretching exercises and their potential role in the management of sleep bruxism or its consequences in the musculoskeletal system.

  5. Acute effect of different stretching methods on isometric muscle strength

    Directory of Open Access Journals (Sweden)

    Gabriel Vasconcellos de Lima Costa e Silva

    2014-03-01

    This study investigated the acute effect of static stretching methods (SS and proprioceptive neuromuscular facilitation (PNF on the static muscle strength (SMS. Eleven young male subjects with strength training experience, performed 3 tests with a 48h interval between them, randomly selected, where each one subject carried out all procedures: a hand grip without stretching; b hand grip preceded by static stretching of wrist flexors muscles; c hand grip preceded by PNF stretching of wrist flexors muscles. The Shapiro-Wilk test verified the normality of data, and a one-way ANOVA with repeated measures, followed by Tukey’s post hoc test, evaluated the differences between the groups. The significance was set at p 0.05. In conclusion, both stretching methods had caused negative effects on isometric strength, reducing its levels.

  6. Linear and nonlinear buckling analysis of a locally stretched plate

    Energy Technology Data Exchange (ETDEWEB)

    Kilardj, Madina; Ikhenzzen, Ghania [University of Sciences and Technology Houari Boumediene (U.S.T.H.B), Bab Ezzouar, Algiers (Algeria); Merssager, Tanguy; Kanit, Toufik [Laboratoire de Mecanique de Lille Universite Lille 1, Cite ScientifiqueVilleneuve d' Ascq cedex (France)

    2016-08-15

    Uniformly stretched thin plates do not buckle unless they are in special boundary conditions. However, buckling commonly occurs around discontinuities, such as cracks, cuts, narrow slits, holes, and different openings, of such plates. This study aims to show that buckling can also occur in thin plates that contain no defect or singularity when the stretching is local. This specific stability problem is analyzed with the finite element method. A brief literature review on stretched plates is presented. Linear and nonlinear buckling stress analyses are conducted for a partially stretched rectangular plate, and various load cases are considered to investigate the influence of the partial loading expanse on the critical tensile buckling load. Results are summarized in iso-stress areas, tables and graphs. Local stretching on one end of the plate induces buckling in the thin plate even without geometrical imperfection.

  7. Optimal design of tunable phononic bandgap plates under equibiaxial stretch

    International Nuclear Information System (INIS)

    Hedayatrasa, Saeid; Abhary, Kazem; Uddin, M S; Guest, James K

    2016-01-01

    Design and application of phononic crystal (PhCr) acoustic metamaterials has been a topic with tremendous growth of interest in the last decade due to their promising capabilities to manipulate acoustic and elastodynamic waves. Phononic controllability of waves through a particular PhCr is limited only to the spectrums located within its fixed bandgap frequency. Hence the ability to tune a PhCr is desired to add functionality over its variable bandgap frequency or for switchability. Deformation induced bandgap tunability of elastomeric PhCr solids and plates with prescribed topology have been studied by other researchers. Principally the internal stress state and distorted geometry of a deformed phononic crystal plate (PhP) changes its effective stiffness and leads to deformation induced tunability of resultant modal band structure. Thus the microstructural topology of a PhP can be altered so that specific tunability features are met through prescribed deformation. In the present study novel tunable PhPs of this kind with optimized bandgap efficiency-tunability of guided waves are computationally explored and evaluated. Low loss transmission of guided waves throughout thin walled structures makes them ideal for fabrication of low loss ultrasound devices and structural health monitoring purposes. Various tunability targets are defined to enhance or degrade complete bandgaps of plate waves through macroscopic tensile deformation. Elastomeric hyperelastic material is considered which enables recoverable micromechanical deformation under tuning finite stretch. Phononic tunability through stable deformation of phononic lattice is specifically required and so any topology showing buckling instability under assumed deformation is disregarded. Nondominated sorting genetic algorithm (GA) NSGA-II is adopted for evolutionary multiobjective topology optimization of hypothesized tunable PhP with square symmetric unit-cell and relevant topologies are analyzed through finite

  8. Reducing vibration transfer from power plants by active methods

    Science.gov (United States)

    Kiryukhin, A. V.; Milman, O. O.; Ptakhin, A. V.

    2017-12-01

    The possibility of applying the methods of active damping of vibration and pressure pulsations for reducing their transfer from power plants into the environment, the seating, and the industrial premises are considered. The results of experimental works implemented by the authors on the active broadband damping of vibration and dynamic forces after shock-absorption up to 15 dB in the frequency band up to 150 Hz, of water pressure pulsations in the pipeline up to 20 dB in the frequency band up to 600 Hz, and of spatial low-frequency air noise indoors of a diesel generator at discrete frequency up to 20 dB are presented. It is shown that a reduction of vibration transfer through a vibration-isolating junction (expansion joints) of pipelines with liquid is the most complicated and has hardly been developed so far. This problem is essential for vibration isolation of power equipment from the seating and the environment through pipelines with water and steam in the power and transport engineering, shipbuilding, and in oil and gas pipelines in pumping stations. For improving efficiency, reducing the energy consumption, and decreasing the overall dimensions of equipment, it is advisable to combine the work of an active system with passive damping means, the use of which is not always sufficient. The executive component of the systems of active damping should be placed behind the vibration isolators (expansion joints). It is shown that the existence of working medium and connection of vibration with pressure pulsations in existing designs of pipeline expansion joints lead to growth of vibration stiffness of the expansion joint with the environment by two and more orders as compared with the static stiffness and makes difficulties for using the active methods. For active damping of vibration transfer through expansion joints of pipelines with a liquid, it is necessary to develop expansion joint structures with minimal connection of vibrations and pulsations and minimal

  9. Acute effects of different stretching durations on passive torque, mobility, and isometric muscle force.

    Science.gov (United States)

    Matsuo, Shingo; Suzuki, Shigeyuki; Iwata, Masahiro; Banno, Yasuhiro; Asai, Yuji; Tsuchida, Wakako; Inoue, Takayuki

    2013-12-01

    Static stretching is widely applied in various disciplines. However, the acute effects of different durations of stretching are unclear. Therefore, this study was designed to investigate the acute effects of different stretching durations on muscle function and flexibility, and provide an insight into the optimal duration of static stretching. This randomized crossover trial included 24 healthy students (17 men and 7 women) who stretched their right hamstrings for durations of 20, 60, 180, and 300 seconds in a random order. The following outcomes were assessed using an isokinetic dynamometer as markers of lower-limb function and flexibility: static passive torque (SPT), dynamic passive torque (DPT), stiffness, straight leg raise (SLR), and isometric muscle force. Static passive torque was significantly decreased after all stretching durations (p stretching compared with that after 20-second stretching, and stiffness decreased significantly after 180- and 300-second stretching (p stretching (p stretching durations (p stretching than after 20-second stretching and higher after 300-second stretching than after 60-second stretching (p muscle force significantly decreased after all stretching durations (p stretching is associated with a decrease in SPT but an increase in SLR. Over 180 seconds of stretching was required to decrease DPT and stiffness, but isometric muscle force decreased regardless of the stretching duration. In conclusion, these results indicate that longer durations of stretching are needed to provide better flexibility.

  10. Vibrations and waves

    CERN Document Server

    Kaliski, S

    2013-01-01

    This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth

  11. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 2nd edition of this textbook on linear stochastic vibration th...... theory is basically unchanged in comparison to the 1st edition. Only section 4.2 on single input - single output systems and chapter 6 on offshore structures have been modified in order to enhance the clearness....

  12. Pre-exercise stretching does not impact upon running economy.

    Science.gov (United States)

    Hayes, Philip R; Walker, Adrian

    2007-11-01

    Pre-exercise stretching has been widely reported to reduce performance in tasks requiring maximal or near-maximal force or torque. The purpose of this study was to compare the effects of 3 different pre-exercise stretching routines on running economy. Seven competitive male middle and long-distance runners (mean +/- SD) age: 32.5 +/- 7.7 years; height: 175.0 +/- 8.8 cm; mass: 67.8 +/- 8.6 kg; V(.-)O2max: 66.8 +/- 7.0 ml x kg(-1) x min(-1)) volunteered to participate in this study. Each participant completed 4 different pre-exercise conditions: (a) a control condition, (b) static stretching, (c) progressive static stretching, and (d) dynamic stretching. Each stretching routine consisted of 2 x 30-second stretches for each of 5 exercises. Dependent variables measured were sit and reach test before and after each pre-exercise routine, running economy (ml x kg(-1) x km(-1)), and steady-state oxygen uptake (ml x kg(-1) x min(-1)), which were measured during the final 3 minutes of a 10-minute run below lactate threshold. All 3 stretching routines resulted in an increase in the range of movement (p = 0.008). There was no change in either running economy (p = 0.915) or steady-state V(.-)O2 (p = 0.943). The lack of change in running economy was most likely because it was assessed after a period of submaximal running, which may have masked any effects from the stretching protocols. Previously reported reductions in performance have been attributed to reduced motor unit activation, presumably IIX. In this study, these motor units were likely not to have been recruited; this may explain the unimpaired performance. This study suggests that pre-exercise stretching has no impact upon running economy or submaximal exercise oxygen cost.

  13. Randomized Controlled Trial Comparing Orthosis Augmented by Either Stretching or Stretching and Strengthening for Stage II Tibialis Posterior Tendon Dysfunction.

    Science.gov (United States)

    Houck, Jeff; Neville, Christopher; Tome, Josh; Flemister, Adolph

    2015-09-01

    The value of strengthening and stretching exercises combined with orthosis treatment in a home-based program has not been evaluated. The purpose of this study was to compare the effects of augmenting orthosis treatment with either stretching or a combination of stretching and strengthening in participants with stage II tibialis posterior tendon dysfunction (TPTD). Participants included 39 patients with stage II TPTD who were recruited from a medical center and then randomly assigned to a strengthening or stretching treatment group. Excluding 3 dropouts, there were 19 participants in the strengthening group and 17 in the stretching group. The stretching treatment consisted of a prefabricated orthosis used in conjunction with stretching exercises. The strengthening treatment consisted of a prefabricated orthosis used in conjunction with the stretching and strengthening exercises. The main outcome measures were self-report (ie, Foot Function Index and Short Musculoskeletal Function Assessment) and isometric deep posterior compartment strength. Two-way analysis of variance was used to test for differences between groups at 6 and 12 weeks after starting the exercise programs. Both groups significantly improved in pain and function over the 12-week trial period. The self-report measures showed minimal differences between the treatment groups. There were no differences in isometric deep posterior compartment strength. A moderate-intensity, home-based exercise program was minimally effective in augmenting orthosis wear alone in participants with stage II TPTD. Level I, prospective randomized study. © The Author(s) 2015.

  14. Thermo-dynamical contours of electronic-vibrational spectra simulated using the statistical quantum-mechanical methods

    DEFF Research Database (Denmark)

    Pomogaev, Vladimir; Pomogaeva, Anna; Avramov, Pavel

    2011-01-01

    Three polycyclic organic molecules in various solvents focused on thermo-dynamical aspects were theoretically investigated using the recently developed statistical quantum mechanical/classical molecular dynamics method for simulating electronic-vibrational spectra. The absorption bands of estradi...

  15. A multireference perturbation study of the NN stretching frequency of trans-azobenzene in nπ* excitation and an implication for the photoisomerization mechanism.

    Science.gov (United States)

    Harabuchi, Yu; Ishii, Moe; Nakayama, Akira; Noro, Takeshi; Taketsugu, Tetsuya

    2013-02-14

    A multireference second-order perturbation theory is applied to calculate equilibrium structures and vibrational frequencies of trans-azobenzene in the ground and nπ* excited states, as well as the reaction pathways for rotation and inversion mechanism in the nπ* excited state. It is found that the NN stretching frequency exhibits a slight increase at the minimum energy structure in the nπ* state, which is explained by the mixing of the NN stretching mode with the CN symmetric stretching mode. We also calculate the NN stretching frequency at several selected structures along the rotation and inversion pathways in the nπ* state, and show that the frequency decreases gradually along the rotation pathway while it increases by ca. 300 cm(-1) along the inversion pathway. The frequencies and energy variations along the respective pathways indicate that the rotation pathway is more consistent with the experimental observation of the NN stretching frequency in nπ* excitation.

  16. Vibrational Analysis of Curved Single-Walled Carbon Nanotube on a Pasternak Elastic Foundation

    DEFF Research Database (Denmark)

    Mehdipour, I.; Barari, Amin; Kimiaeifar, Amin

    2012-01-01

    Continuum mechanics and an elastic beam model were employed in the nonlinear force vibrational analysis of an embedded, curved, single-walled carbon nanotube. The analysis considered the effects of the curvature or waviness and midplane stretching of the nanotube on the nonlinear frequency....... By utilizing He’s Energy Balance Method (HEBM), the relationships of the nonlinear amplitude and frequency were expressed for a curved, single-walled carbon nanotube. The amplitude frequency response curves of the nonlinear free vibration were obtained for a curved, single-walled carbon nanotube embedded...... in a Pasternak elastic foundation. Finally, the influence of the amplitude of the waviness, midplane stretching nonlinearity, shear foundation modulus, surrounding elastic medium, radius, and length of the curved carbon nanotube on the amplitude frequency response characteristics are discussed. As a result...

  17. Reflectors Made from Membranes Stretched Between Beams

    Science.gov (United States)

    Dooley, Jennifer; Dragovan, Mark; Tolomeo, Jason

    2009-01-01

    Lightweight cylindrical reflectors of a proposed type would be made from reflective membranes stretched between pairs of identically curved and identically oriented end rails. In each such reflector, the curvature of the two beams would define the reflector shape required for the intended application. For example, the beams could be curved to define a reflector of parabolic cross section, so that light incident along the axis of symmetry perpendicular to the cylindrical axis would be focused to a line. In addition, by applying suitable forces to the ends of the beams, one could bend the beams to adjust the reflector surface figure to within a precision of the order of the wavelength of the radiation to be reflected. The figure depicts an example of beams shaped so that in the absence of applied forces, each would be flat on one side and would have a radius of curvature R on the opposite side. Alternatively, the curvature of the reflector-membrane side could be other than circular. In general, the initial curvature would be chosen to optimize the final reflector shape. Then by applying forces F between the beam ends in the positions and orientations shown in the figure, one could bend beams to adjust their shape to a closer approximation of the desired precise circular or noncircular curvature.

  18. Linear viscoelastic characterization from filament stretching rheometry

    DEFF Research Database (Denmark)

    Wingstrand, Sara Lindeblad; Alvarez, Nicolas J.; Hassager, Ole

    Traditionally, linear viscoelasticity is measured using small amplitude oscillatory shear flow. Due to experimental difficulties, shear flows are predominately confined to the linear and mildly nonlinear regime. On the other hand, extensional flows have proven more practical in measuring viscoela......Traditionally, linear viscoelasticity is measured using small amplitude oscillatory shear flow. Due to experimental difficulties, shear flows are predominately confined to the linear and mildly nonlinear regime. On the other hand, extensional flows have proven more practical in measuring...... viscoelasticity well into the nonlinear regime. Therefore at present, complete rheological characterization of a material requires two apparatuses: a shear and an extensional rheometer. This work is focused on developing a linear viscoelastic protocol for the filament stretching rheometer (FSR) in order...... to measure both linear and nonlinear dynamics on a single apparatus. With a software modification to the FSR motor control, we show that linear viscoelasticity can be measured via small amplitude squeeze flow (SASF). Squeeze flow is a combination of both shear and extensional flow applied by axially...

  19. Composite Struts Would Damp Vibrations

    Science.gov (United States)

    Dolgin, Benjamin P.

    1991-01-01

    New design of composite-material (fiber/matrix laminate) struts increases damping of longitudinal vibrations without decreasing longitudinal stiffness or increasing weight significantly. Plies with opposing chevron patterns of fibers convert longitudinal vibrational stresses into shear stresses in intermediate viscoelastic layer, which dissipate vibrational energy. Composite strut stronger than aluminum strut of same weight and stiffness.

  20. Development of vibrating insoles

    NARCIS (Netherlands)

    Hijmans, J.M.; Geertzen, J.H.B.; Schokker, B.; Postema, K.

    2007-01-01

    The objective of this study was to describe the development of vibrating insoles. Insoles, providing a subsensory mechanical noise signal to the plantar side of the feet, may improve balance in healthy young and older people and in patients with stroke or diabetic neuropathy. This study describes

  1. Vibrational Spectroscopy and Astrobiology

    Science.gov (United States)

    Chaban, Galina M.; Kwak, D. (Technical Monitor)

    2001-01-01

    Role of vibrational spectroscopy in solving problems related to astrobiology will be discussed. Vibrational (infrared) spectroscopy is a very sensitive tool for identifying molecules. Theoretical approach used in this work is based on direct computation of anharmonic vibrational frequencies and intensities from electronic structure codes. One of the applications of this computational technique is possible identification of biological building blocks (amino acids, small peptides, DNA bases) in the interstellar medium (ISM). Identifying small biological molecules in the ISM is very important from the point of view of origin of life. Hybrid (quantum mechanics/molecular mechanics) theoretical techniques will be discussed that may allow to obtain accurate vibrational spectra of biomolecular building blocks and to create a database of spectroscopic signatures that can assist observations of these molecules in space. Another application of the direct computational spectroscopy technique is to help to design and analyze experimental observations of ice surfaces of one of the Jupiter's moons, Europa, that possibly contains hydrated salts. The presence of hydrated salts on the surface can be an indication of a subsurface ocean and the possible existence of life forms inhabiting such an ocean.

  2. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author...

  3. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    rical or mechanical reasonings, but solely algebraic [analytic] operations subjected to a uniform and regular procedure. Those. Keywords. Vibrations, eigenvalues .... Suggested Reading. [1] R Bhatia, Fourier Series, Hindustan Book Agency, Second Edition, 2003. [2] G Strang, Essays in Linear Algebra, SIAM, 2012. 872.

  4. Compact Vibration Damper

    Science.gov (United States)

    Ivanco, Thomas G. (Inventor)

    2014-01-01

    A vibration damper includes a rigid base with a mass coupled thereto for linear movement thereon. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A converter coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement.

  5. Blade Vibration Measurement System

    Science.gov (United States)

    Platt, Michael J.

    2014-01-01

    The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.

  6. Man-Induced Vibrations

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Hansen, Lars Pilegaard

    1994-01-01

    work has been done on the measurement of the exact load functions and related reponse analysis. A recent work using a spectral description has been performed by Per-Erik Erikson and includes a good literature survey. Bachmann and Ammann give a good overview of vibrations caused by human activity. Other...

  7. Vibration characteristics of ultrasonic complex vibration for hole machining

    Science.gov (United States)

    Asami, Takuya; Miura, Hikaru

    2012-05-01

    Complex vibration sources that use diagonal slits as a longitudinal-torsional vibration converter have been applied to ultrasonic motors, ultrasonic rock drilling, and ultrasonic welding. However, there are few examples of the application of these sources to ultrasonic machining in combination with an abrasive. Accordingly, a new method has been developed for machining of holes in brittle materials by using the ultrasonic longitudinal and torsional vibration of a hollow-type stepped horn with a diagonal slit vibration converter. In this paper, we compared vibration of a uniform rod and a hollow-type stepped horn, both with diagonal slits, when the conditions of the diagonal slits are constant.

  8. Wide Band to ''Double Band'' upgrade

    International Nuclear Information System (INIS)

    Kasper, P.; Currier, R.; Garbincius, P.; Butler, J.

    1988-06-01

    The Wide Band beam currently uses electrons obtained from secondary photon conversions to produce the photon beam incident on the experimental targets. By transporting the positrons produced in these conversions as well as the electrons it is possible to almost double the number of photons delivered to the experiments per primary beam proton. 11 figs

  9. A vibration powered wireless mote on the Forth Road Bridge

    International Nuclear Information System (INIS)

    Jia, Yu; Yan, Jize; Feng, Tao; Du, Sijun; Fidler, Paul; Soga, Kenichi; Middleton, Campbell; Seshia, Ashwin A

    2015-01-01

    The conventional resonant-approaches to scavenge kinetic energy are typically confined to narrow and single-band frequencies. The vibration energy harvester device reported here combines both direct resonance and parametric resonance in order to enhance the power responsiveness towards more efficient harnessing of real-world ambient vibration. A packaged electromagnetic harvester designed to operate in both of these resonant regimes was tested in situ on the Forth Road Bridge. In the field-site, the harvester, with an operational volume of ∼126 cm 3 , was capable of recovering in excess of 1 mW average raw AC power from the traffic-induced vibrations in the lateral bracing structures underneath the bridge deck. The harvester was integrated off-board with a power conditioning circuit and a wireless mote. Duty- cycled wireless transmissions from the vibration-powered mote was successfully sustained by the recovered ambient energy. This limited duration field test provides the initial validation for realising vibration-powered wireless structural health monitoring systems in real world infrastructure, where the vibration profile is both broadband and intermittent. (paper)

  10. A vibration powered wireless mote on the Forth Road Bridge

    Science.gov (United States)

    Jia, Yu; Yan, Jize; Feng, Tao; Du, Sijun; Fidler, Paul; Soga, Kenichi; Middleton, Campbell; Seshia, Ashwin A.

    2015-12-01

    The conventional resonant-approaches to scavenge kinetic energy are typically confined to narrow and single-band frequencies. The vibration energy harvester device reported here combines both direct resonance and parametric resonance in order to enhance the power responsiveness towards more efficient harnessing of real-world ambient vibration. A packaged electromagnetic harvester designed to operate in both of these resonant regimes was tested in situ on the Forth Road Bridge. In the field-site, the harvester, with an operational volume of ∼126 cm3, was capable of recovering in excess of 1 mW average raw AC power from the traffic-induced vibrations in the lateral bracing structures underneath the bridge deck. The harvester was integrated off-board with a power conditioning circuit and a wireless mote. Duty- cycled wireless transmissions from the vibration-powered mote was successfully sustained by the recovered ambient energy. This limited duration field test provides the initial validation for realising vibration-powered wireless structural health monitoring systems in real world infrastructure, where the vibration profile is both broadband and intermittent.

  11. STRETCH FABRICS IN LEATHER MANUFACTURING: PERFORMANCE PROPERTIES OF STRECH LEATHERS

    Directory of Open Access Journals (Sweden)

    ORK Nilay

    2016-05-01

    Full Text Available Product variability of manufactured leather goods such as garment leathers could be closely related to the wear comfort because each material forming the garments are affected the comfort properties of the products. Considering the significant demand to elastic woven stretch fabrics and the advantages provided to leather goods like allowing easy body movements, well-fitting and keeping the shape make the use of stretch fabrics focus in interest. In this study, the performance properties of stretch leathers, leathers and spandex fabrics were presented and the differences between the characteristic properties of the leathers were described. For this purpose, physical characteristics of leathers were investigated in terms of thickness, weight, drape ability, stiffness, bending stiffness, air and water vapor permeability. The drape ability, stiffness and bending stiffness properties were significantly affected by the stretch fabrics laminated on the suede side of the leathers. The drape ability, stiffness and bending values were increased due to the implementation of stretch fabrics. There was no significant difference between the air permeability values of the leathers prior and after the implementation of stretch fabrics in contrast to water vapor permeability. The results of this study showed that the aesthetic behavior of clothing materials such as drape and stiffness properties as well as water vapor permeability was mainly affected from the implementation of the stretch fabrics.

  12. Vibrational spectroscopic study of sulphated silk proteins

    Science.gov (United States)

    Monti, P.; Freddi, G.; Arosio, C.; Tsukada, M.; Arai, T.; Taddei, P.

    2007-05-01

    Degummed Bombyx mori ( B. m.) silk fibroin fabric and mutant naked pupa cocoons (Nd-s) consisting of almost pure silk sericin were treated with chlorosulphonic acid in pyridine and investigated by FT-IR and FT-Raman spectroscopies. Untreated silk fibroin and sericin displayed typical spectral features due to characteristic amino acid composition and molecular conformation (prevailing β-sheet with a less ordered structure in sericin). Upon sulphation, the degree of molecular disorder increased in both proteins and new bands appeared. The IR bands at 1049 and 1014 cm -1 were attributed to vibrations of sulphate salts and that at 1385 cm -1 to the νasSO 2 mode of organic covalent sulphates. In the 1300-1180 cm -1 range various contributions of alkyl and aryl sulphate salts, sulphonamides, sulphoamines and organic covalent sulphates, fell. Fibroin covalently bound sulphate groups through the hydroxyl groups of tyrosine and serine, while sericin through the hydroxyl groups of serine, since the δOH vibrations at 1399 cm -1 in IR and at 1408 cm -1 in Raman disappeared almost completely. Finally, the increase of the I850/ I830 intensity ratio of Raman tyrosine doublet in fibroin suggested a change towards a more exposed state of tyrosine residues, in good agreement with the more disordered conformation taken upon sulphation.

  13. Measurement of rabbit eardrum vibration through stroboscopic digital holography

    Energy Technology Data Exchange (ETDEWEB)

    De Greef, Daniël; Dirckx, Joris J. J. [University of Antwerp, Laboratory of BioMedical Physics, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2014-05-27

    In this work, we present a setup for high-power single shot stroboscopic digital holography and demonstrate it in an application on rabbit eardrum vibration measurement. The setup is able to make full-field time-resolved measurements of vibrating surfaces with a precision in the nanometer range in a broad frequency range. The height displacement of the measured object is visualized over the entire surface as a function of time. Vibration magnitude and phase maps can be extracted from these data, the latter proving to be very useful to reveal phase delays across the surface. Such deviations from modal motion indicate energy losses due to internal damping, in contrast to purely elastic mechanics. This is of great interest in middle ear mechanics and finite element modelling. In our setup, short laser pulses are fired at selected instants within the surface vibration period and are recorded by a CCD camera. The timing of the pulses and the exposure of the camera are synchronized to the vibration phase by a microprocessor. The high-power frequency-doubled Nd:YAG laser produces pulses containing up to 5 mJ of energy, which is amply sufficient to record single-shot holograms. As the laser pulse length is 8 ns and the smallest time step of the trigger electronics is 1 μs, vibration measurements of frequencies up to 250 kHz are achievable through this method, provided that the maximum vibration amplitude exceeds a few nanometers. In our application, middle ear mechanics, measuring frequencies extend from 5 Hz to 20 kHz. The experimental setup will be presented, as well as results of measurements on a stretched circular rubber membrane and a rabbit's eardrum. Two of the challenges when measuring biological tissues, such as the eardrum, are low reflectivity and fast dehydration. To increase reflectivity, a coating is applied and to counteract the undesirable effects of tissue dehydration, the measurement setup and software have been optimized for speed without

  14. Magnitude and duration of stretch modulate fibroblast remodeling.

    Science.gov (United States)

    Balestrini, Jenna L; Billiar, Kristen L

    2009-05-01

    Mechanical cues modulate fibroblast tractional forces and remodeling of extracellular matrix in healthy tissue, healing wounds, and engineered matrices. The goal of the present study is to establish dose-response relationships between stretch parameters (magnitude and duration per day) and matrix remodeling metrics (compaction, strength, extensibility, collagen content, contraction, and cellularity). Cyclic equibiaxial stretch of 2-16% was applied to fibroblast-populated fibrin gels for either 6 h or 24 h/day for 8 days. Trends in matrix remodeling metrics as a function of stretch magnitude and duration were analyzed using regression analysis. The compaction and ultimate tensile strength of the tissues increased in a dose-dependent manner with increasing stretch magnitude, yet remained unaffected by the duration in which they were cycled (6 h/day versus 24 h/day). Collagen density increased exponentially as a function of both the magnitude and duration of stretch, with samples stretched for the reduced duration per day having the highest levels of collagen accumulation. Cell number and failure tension were also dependent on both the magnitude and duration of stretch, although stretch-induced increases in these metrics were only present in the samples loaded for 6 h/day. Our results indicate that both the magnitude and the duration per day of stretch are critical parameters in modulating fibroblast remodeling of the extracellular matrix, and that these two factors regulate different aspects of this remodeling. These findings move us one step closer to fully characterizing culture conditions for tissue equivalents, developing improved wound healing treatments and understanding tissue responses to changes in mechanical environments during growth, repair, and disease states.

  15. Investigation on Vibration Characteristics in a Centrifugal Pump with Special Slope Volute

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2015-02-01

    Full Text Available Vibration is one of the main problems which should be considered seriously in designing and operating a centrifugal pump. In this paper, a special slope volute was proposed to reduce vibration level of centrifugal pump. The goal of this paper was to analyze vibration characteristics of slope volute pump and provide a new method to reduce vibration energy in centrifugal pump. Experiments were carried out to obtain vibration signals at different flow rates of slope volute pump, which were compared with conventional spiral volute pump. Results show that vibration level is closely related to flow structure interior pump. At low flow rates, especially, vibration energy increases rapidly with the onset of rotating stall. Rotor-stator interaction mechanism changes when adopting slope volute. In slope volute pump, the peaks in power spectra correspond to different harmonics of fBPF at three measuring directions; however, in spiral volute pump, the predominant components always correspond to 2fBPF. From comparison of vibration level in different frequency bands, it is found that vibration level of slope volute pump is smaller than conventional spiral volute pump. So vibration energy of centrifugal pump can be reduced effectively using slope volute.

  16. The effects of vibration-reducing gloves on finger vibration

    Science.gov (United States)

    Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

    2015-01-01

    Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understanding of the glove effects on finger vibration and provided useful information on the effectiveness of typical VR gloves at reducing the vibration transmitted to the fingers. The new

  17. Band - Weg interactie

    NARCIS (Netherlands)

    de Boer, Andries; ter Huerne, Henderikus L.; Noordermeer, Jacobus W.M.; Schipper, Dirk J.; prof.dr.ir. Molenaar, A.A.A.

    2008-01-01

    De huidige infrastructuur van wegen waarover men zich snel en comfortabel kan verplaatsen is niet meer weg te denken uit onze maatschappij. Twee “componenten” die hierbij een belangrijke rol spelen zijn het wegdek en de band. Het contact tussen band en wegdek is mede bepalend voor de veiligheid. De

  18. Photonic band structure computations.

    Science.gov (United States)

    Hermann, D; Frank, M; Busch, K; Wolfle, P

    2001-01-29

    We introduce a novel algorithm for band structure computations based on multigrid methods. In addition, we demonstrate how the results of these band structure calculations may be used to compute group velocities and effective photon masses. The results are of direct relevance to studies of pulse propagation in such materials.

  19. ZEBRAFISH CHROMOSOME-BANDING

    NARCIS (Netherlands)

    PIJNACKER, LP; FERWERDA, MA

    1995-01-01

    Banding techniques were carried out on metaphase chromosomes of zebrafish (Danio rerio) embryos. The karyotypes with the longest chromosomes consist of 12 metacentrics, 26 submetacentrics, and 12 subtelocentrics (2n = 50). All centromeres are C-band positive. Eight chromosomes have a pericentric

  20. AI-augmented time stretch microscopy

    Science.gov (United States)

    Mahjoubfar, Ata; Chen, Claire L.; Lin, Jiahao; Jalali, Bahram

    2017-02-01

    Cell reagents used in biomedical analysis often change behavior of the cells that they are attached to, inhibiting their native signaling. On the other hand, label-free cell analysis techniques have long been viewed as challenging either due to insufficient accuracy by limited features, or because of low throughput as a sacrifice of improved precision. We present a recently developed artificial-intelligence augmented microscope, which builds upon high-throughput time stretch quantitative phase imaging (TS-QPI) and deep learning to perform label-free cell classification with record high-accuracy. Our system captures quantitative optical phase and intensity images simultaneously by frequency multiplexing, extracts multiple biophysical features of the individual cells from these images fused, and feeds these features into a supervised machine learning model for classification. The enhanced performance of our system compared to other label-free assays is demonstrated by classification of white blood T-cells versus colon cancer cells and lipid accumulating algal strains for biofuel production, which is as much as five-fold reduction in inaccuracy. This system obtains the accuracy required in practical applications such as personalized drug development, while the cells remain intact and the throughput is not sacrificed. Here, we introduce a data acquisition scheme based on quadrature phase demodulation that enables interruptionless storage of TS-QPI cell images. Our proof of principle demonstration is capable of saving 40 TB of cell images in about four hours, i.e. pictures of every single cell in 10 mL of a sample.

  1. Acute effect of constant torque and angle stretching on range of motion, muscle passive properties, and stretch discomfort perception.

    Science.gov (United States)

    Cabido, Christian E T; Bergamini, Juliana C; Andrade, André G P; Lima, Fernando V; Menzel, Hans J; Chagas, Mauro H

    2014-04-01

    The aim of the present study was to compare the acute effects of constant torque (CT) and constant angle (CA) stretching exercises on the maximum range of motion (ROMmax), passive stiffness (PS), and ROM corresponding to the first sensation of tightness in the posterior thigh (FSTROM). Twenty-three sedentary men (age, 19-33 years) went through 1 familiarization session and afterward proceeded randomly to both CA and CT treatment stretching conditions, on separate days. An isokinetic dynamometer was used to analyze hamstring muscles during passive knee extension. The subjects performed 4 stretches of 30 seconds each with a 15-second interval between them. In the CA stretching, the subject reached a certain ROM (95% of ROMmax), and the angle was kept constant. However, in the CT stretching exercise, the volunteer reached a certain resistance torque (corresponding to 95% of ROMmax) and it was kept constant. The results showed an increase in ROMmax for both CA and CT (p stretch may be explained by greater changes in the biomechanical properties of the muscle-tendon unit and stretch tolerance, as indicated by the results of PS and FSTROM.

  2. Structural, optical and vibrational studies of Na{sup +} doped Cd{sub 0.8}Zn{sub 0.2}S semiconductor compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yellaiah, G., E-mail: johngolluri@yahoo.com; Hadasa, K.; Nagabhushanam, M., E-mail: mamidala_nb@yahoo.com

    2013-12-25

    Graphical abstract: FTIR spectra of Cd{sub 0.8}Zn{sub 0.2}S: N{sub x} (x = 0.2 mol%). Highlights: •The energy band gaps of Cd{sub 0.8}Zn{sub 02}S: Nasamples were estimated. •Density and porosity percentages were calculated. •From the FTIR study CdS and ZnS stretching bonds were detected. -- Abstract: Cd{sub 0.8}Zn{sub 0.2}S semiconductor powders doped with different amounts of sodium have been synthesized by controlled co-precipitation technique. X-ray diffraction (XRD), Scanning electron microscope (SEM), Optical absorption and Fourier transform infrared spectroscope (FTIR) studies have been done on all these samples. XRD studies have revealed that the samples are polycrystalline with an average crystallite size ranging from 29 to 55 nm and they crystallize in the hexagonal form with wurtzite structure. The optical measurements revealed that the samples possess direct band gap and the band gap increases with an increase in the dopant concentration. The vibrational modes of Cd–S and Zn–S were obtained from FTIR studies and found to be at 812–618 cm{sup −1} respectively. Experimental and theoretical (XRD) densities were calculated and analyzed. Density from XRD and porosity in percentage varied from 92% to 94% and 5% to 8% respectively. The elemental analysis of the compounds was done by energy dispersive spectroscopy (EDS) and found that the cadmium, zinc, sulphur and sodium elements were present in the compound as per the composition taken. From the theoretical estimations it is understood that the dopant (Na) occupies the interstitial of CdZnS.

  3. Passive and active vibration isolation systems using inerter

    Science.gov (United States)

    Alujević, N.; Čakmak, D.; Wolf, H.; Jokić, M.

    2018-03-01

    This paper presents a theoretical study on passive and active vibration isolation schemes using inerter elements in a two degree of freedom (DOF) mechanical system. The aim of the work is to discuss basic capabilities and limitations of the vibration control systems at hand using simple and physically transparent models. Broad frequency band dynamic excitation of the source DOF is assumed. The purpose of the isolator system is to prevent vibration transmission to the receiving DOF. The frequency averaged kinetic energy of the receiving mass is used as the metric for vibration isolation quality. It is shown that the use of inerter element in the passive vibration isolation scheme can enhance the isolation effect. In the active case, a feedback disturbance rejection scheme is considered. Here, the error signal is the receiving body absolute velocity which is directly fed to a reactive force actuator between the source and the receiving bodies. In such a scheme, the so-called subcritical vibration isolation problems exist. These problems are characterised by the uncoupled natural frequency of the receiving body larger than the uncoupled natural frequency of the source body. In subcritical vibration isolation problems, the performance of the active control is limited by poor stability margins. This is because the stable feedback gain is restricted in a narrow range between a minimum and a maximum. However, with the inclusion of an inerter in the isolator, one of the two stability margins can be opened. This enables large, theoretically unlimited negative feedback gains and large active damping of the receiving body vibration. A simple expression for the required inertance is derived.

  4. Vibration Attenuation of Plate Using Multiple Vibration Absorbers

    Directory of Open Access Journals (Sweden)

    Zaman Izzuddin

    2014-07-01

    Full Text Available Vibrations are undesired phenomenon and it can cause harm, distress and unsettling influence to the systems or structures, for example, aircraft, automobile, machinery and building. One of the approach to limit this vibration by introducing passive vibration absorber attached to the structure. In this paper, the adequacy of utilizing passive vibration absorbers are investigated. The vibration absorber system is designed to minimize the vibration of a thin plate fixed along edges. The plate’s vibration characteristics, such as, natural frequency and mode shape are determined using three techniques: theoretical equations, finite element (FE analysis and experiment. The results demonstrate that the first four natural frequencies of fixed-fixed ends plate are 48, 121, 193 and 242 Hz, and these results are corroborated well with theoretical, FE simulation and experiment. The experiment work is further carried out with attached single and multiple vibration absorbers onto plate by tuning the absorber’s frequency to match with the excitation frequency. The outcomes depict that multiple vibration absorbers are more viable in lessening the global structural vibration.

  5. Effects of Static Stretching and Playing Soccer on Knee Laxity

    NARCIS (Netherlands)

    Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W.; Freiwald, Juergen

    2015-01-01

    Objective: This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Design: Randomized controlled trial. Setting: University biomechanics laboratory. Participants: Thirty-one athletes were randomly assigned into

  6. Shaft Crack Identification Based on Vibration and AE Signals

    Directory of Open Access Journals (Sweden)

    Wenxiu Lu

    2011-01-01

    Full Text Available The shaft crack is one of the main serious malfunctions that often occur in rotating machinery. However, it is difficult to locate the crack and determine the depth of the crack. In this paper, the acoustic emission (AE signal and vibration response are used to diagnose the crack. The wavelet transform is applied to AE signal to decompose into a series of time-domain signals, each of which covers a specific octave frequency band. Then an improved union method based on threshold and cross-correlation method is applied to detect the location of the shaft crack. The finite element method is used to build the model of the cracked rotor, and the crack depth is identified by comparing the vibration response of experiment and simulation. The experimental results show that the AE signal is effective and convenient to locate the shaft crack, and the vibration signal is feasible to determine the depth of shaft crack.

  7. EFFECT OF STATIC STRETCHING ON STRENGTH OF HAMSTRING MUSCLE

    Directory of Open Access Journals (Sweden)

    Shweta P Pachpute

    2016-04-01

    Full Text Available Background: Flexibility is an indisputable component of fitness defined as the ability to move a single joint or series of joints through an unrestricted pain free range of motion. Static stretching consists of stretching a muscle or group of muscle to its farthest point and then maintaining or holding that position. The literature supports that muscles are capable of exerting their greatest strength when they are fully lengthen. Hence this study was conducted to find the effect of static stretching on hamstring muscle. Methods: The study was experimental study design. 40 samples were selected by purposive sampling method. Flexibility of the hamstring muscle unilaterally right side (arbitrarily chosen was measured by active knee extension test of all the subjects who met the inclusion criteria of the study. After measuring the flexibility of hamstring muscle, strength was measured by 1RM for the same side (right hamstring muscle. Static Stretching Protocol was given for 5 days per week for 6 weeks to all the participants. After the 6 weeks of training, knee extension deficiency and 1RM was documented. Result: Statistical analysis using Paired t-test was done. The t-test showed that there was significant effect of static stretching on 1RM of hamstring muscle (p<0.05 & active knee extension test (p=0.000. Conclusion: Static stretching showed significant change in pre and post 1RM of hamstring muscle and active knee extension test. There was significant improvement of hamstring muscles flexibility and strength after giving static stretching in female population. So it is possible that females who are unable to participate in traditional strength training activities may be able to experience gains through static stretching.

  8. Effects of right atrial stretch on plasma renin activity.

    Science.gov (United States)

    Annat, G; Grandjean, B; Vincent, M; Jarsaillon, E; Sassard, J

    1976-04-01

    In anaesthetized dog, right atrial stretch leads in the first five minutes to a decrease in plasma renin activity, when measured in inferior vena cava just above the renal veins. Bilateral cervical vagotomy increases plasma renin activity. After vagotomy, atrial stretch no longer has any effect on plasma renin activity. The results support the hypothesis of a control of renin secretion originating from atrial volume receptors.

  9. Oblate bands in A ∼ 200 bismuth nuclei

    International Nuclear Information System (INIS)

    Dagnall, P.J.; Beausang, C.W.; Clark, R.M.

    1994-01-01

    The nuclei 198-200 Bi were populated via the 186 W( 19 F,xn) 198-200 Bi reaction at beam energies of 115 MeV and 105 MeV. Another experiment, aimed at investigating the high-spin-level structure of 203,204 Bi, used the 198 Pt( 11 B,xn) reaction at a beam energy of 74 MeV. Five new ΔI = 1 rotational structures, consisting of stretched magnetic dipole transitions, have been observed. One of these bands is assigned to 198 Bi, one to 199 Bi, two to 200 Bi, and one to 203 Bi. The behaviour of the dynamic moments of inertia of these oblate bands is compared with other bands in neighbouring Pb and Bi nuclei. (author)

  10. Customized DSP-based vibration measurement for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    LaWhite, N.E.; Cohn, K.E. [Second Wind Inc., Somerville, MA (United States)

    1996-12-31

    As part of its Advanced Distributed Monitoring System (ADMS) project funded by NREL, Second Wind Inc. is developing a new vibration measurement system for use with wind turbines. The system uses low-cost accelerometers originally designed for automobile airbag crash-detection coupled with new software executed on a Digital Signal Processor (DSP) device. The system is envisioned as a means to monitor the mechanical {open_quotes}health{close_quotes} of the wind turbine over its lifetime. In addition the system holds promise as a customized emergency vibration detector. The two goals are very different and it is expected that different software programs will be executed for each function. While a fast Fourier transform (FFT) signature under given operating conditions can yield much information regarding turbine condition, the sampling period and processing requirements make it inappropriate for emergency condition monitoring. This paper briefly reviews the development of prototype DSP and accelerometer hardware. More importantly, it reviews our work to design prototype vibration alarm filters. Two-axis accelerometer test data from the experimental FloWind vertical axis wind turbine is analyzed and used as a development guide. Two levels of signal processing are considered. The first uses narrow band pre-processing filters at key fundamental frequencies such as the 1P, 2P and 3P. The total vibration energy in each frequency band is calculated and evaluated as a possible alarm trigger. In the second level of signal processing, the total vibration energy in each frequency band is further decomposed using the two-axis directional information. Directional statistics are calculated to differentiate between linear translations and circular translations. After analyzing the acceleration statistics for normal and unusual operating conditions, the acceleration processing system described could be used in automatic early detection of fault conditions. 9 figs.

  11. Vibrational stability of graphene

    Directory of Open Access Journals (Sweden)

    Yangfan Hu

    2013-05-01

    Full Text Available The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP models. Compared with three-dimensional (3-D materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202. This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC, defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D materials.

  12. Pickin’ up good vibrations

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    In preparation for the civil engineering work on the HL-LHC, vibration measurements were carried out at the LHC’s Point 1 last month. These measurements will help evaluate how civil engineering work could impact the beam, and will provide crucial details about the site’s geological make-up before construction begins.   A seismic truck at Point 1 generated wave-like vibrations measured by EN/MME. From carrying out R&D to produce state-of-the-art magnets to developing innovative, robust materials capable of withstanding beam impact, the HL-LHC is a multi-faceted project involving many groups and teams across CERN’s departments. It was in this framework that the project management mandated CERN's Mechanical and Materials Engineering (EN/MME) group to measure the propagation of vibrations around Point 1. Their question: can civil engineering work for the HL-LHC – the bulk of which is scheduled for LS2 – begin while the LHC is running? Alth...

  13. Efficacy of hamstring stretching programs in schoolchildren. A systematic review

    Directory of Open Access Journals (Sweden)

    Carlos-Alberto BECERRA FERNANDEZ

    2017-03-01

    Full Text Available The main purpose of the present review was to examine the scientific literature on the effects of physical education-based stretching programs on hamstring extensibility in schoolchildren aged 6-11 years. For this purpose relevant studies were searched from ten electronic databases dated up through May 2015. Of the 25 potentially relevant articles identified and retrieved for more detailed evaluation, only eight studies were included in the present review because they met the inclusion criteria. The overall results showed that incorporating hamstring stretching as a part of physical education classes produces a significant improvement in the scores of the tests: straight leg raise and classic sit-and-reach, for the experimental groups, but not for control groups. Stretching programs can be included in Physical Education classes, specifically during the warm-up and the cool down periods in order to improve hamstring extensibility. Although it seems that the stretching exercises in the warm-up period could be less effective in gaining flexibility in school children. Studies that use a stretching volume between 4 and 7 minutes per session and 2-4 training classes per week, obtain statistically significant improvements on the levels of hamstring flexibility in the experimental groups. However, after a five-week detraining period, children revert back to their initial flexibility levels. Therefore, it seems appropriate that physical education teachers should implement stretching programs to improve the students´ flexibility during the Physical Education classes.

  14. Equibiaxial cyclic stretch stimulates fibroblasts to rapidly remodel fibrin.

    Science.gov (United States)

    Balestrini, Jenna Leigh; Billiar, Kristen Lawrence

    2006-01-01

    Understanding the effects of the mechanical environment on wound healing is critical for developing more effective treatments to reduce scar formation and contracture. The aim of this study was to investigate the effects of dynamic mechanical stretch on cell-mediated early wound remodeling independent of matrix alignment which obscures more subtle remodeling mechanisms. Cyclic equibiaxial stretch (16% stretch at 0.2 Hz) was applied to fibroblast-populated fibrin gel in vitro wound models for eight days. Compaction, density, tensile strength, and collagen content were quantified as functional measures of remodeling. Stretched samples were approximately ten times stronger, eight-fold more dense, and eight times thinner than statically cultured samples. These changes were accompanied by a 15% increase in net collagen but no significant differences in cell number or viability. When collagen crosslinking was inhibited in stretched samples, the extensibility increased and the strength decreased. The apparent weakening was due to a reduction in compaction rather than a decrease in ability of the tissue to withstand tensile forces. Interestingly, inhibiting collagen crosslinking had no measurable effects on the statically cultured samples. These results indicate that amplified cell-mediated compaction and even a slight addition in collagen content play substantial roles in mechanically induced wound strengthening. These findings increase our understanding of how mechanical forces guide the healing response in skin, and the methods employed in this study may also prove valuable tools for investigating stretch-induced remodeling of other planar connective tissues and for creating mechanically robust engineered tissues.

  15. Effects of Stretching Exercise on Heart Rate Variability During Pregnancy.

    Science.gov (United States)

    Logan, Jeongok G; Yeo, SeonAe

    Little evidence exists for effects of low-intensity exercises such as stretching on cardiovascular health in pregnant women. Our aim was to evaluate the effect of a 20-minute stretching exercise on heart rate variability (HRV), blood pressure (BP), and heart rate (HR) in healthy pregnant women. In 15 pregnant women with a mean (SD) age of 29.47 (4.07) years and mean (SD) gestational weeks of 26.53 (8.35), HRV, and BP were measured before and after the 20-minute stretching exercise. Compared with before the stretching exercise, standard deviation of the normal-to-normal intervals, total variability of heart rate, increased by 7.40 milliseconds (t = -2.31, P = .04) and root mean square of successive differences, a surrogate measure of parasympathetic outflow, also increased by 11.68 milliseconds (Z = -2.04, P = .04) after the stretching exercise. Diastolic BP and HR decreased by 2.13 mm Hg (t = 1.93, P = .07) and 3.31 bpm (t = 2.17, P = .05), respectively, but they did not reach statistical significance. These preliminary data suggest that 20 minutes of stretching exercise may promote cardiovascular health by attenuating the loss of parasympathetic tone associated with pregnancy.

  16. Opening complete band gaps in two dimensional locally resonant phononic crystals

    Science.gov (United States)

    Zhou, Xiaoling; Wang, Longqi

    2018-05-01

    Locally resonant phononic crystals (LRPCs) which have low frequency band gaps attract a growing attention in both scientific and engineering field recently. Wide complete locally resonant band gaps are the goal for researchers. In this paper, complete band gaps are achieved by carefully designing the geometrical properties of the inclusions in two dimensional LRPCs. The band structures and mechanisms of different types of models are investigated by the finite element method. The translational vibration patterns in both the in-plane and out-of-plane directions contribute to the full band gaps. The frequency response of the finite periodic structures demonstrate the attenuation effects in the complete band gaps. Moreover, it is found that the complete band gaps can be further widened and lowered by increasing the height of the inclusions. The tunable properties by changing the geometrical parameters provide a good way to open wide locally resonant band gaps.

  17. Band parameters of phosphorene

    DEFF Research Database (Denmark)

    Lew Yan Voon, L. C.; Wang, J.; Zhang, Y.

    2015-01-01

    Phosphorene is a two-dimensional nanomaterial with a direct band-gap at the Brillouin zone center. In this paper, we present a recently derived effective-mass theory of the band structure in the presence of strain and electric field, based upon group theory. Band parameters for this theory...... are computed using a first-principles theory based upon the generalized-gradient approximation to the density-functional theory. These parameters and Hamiltonian will be useful for modeling physical properties of phosphorene....

  18. [Sciatica. From stretch rack to microdiscectomy].

    Science.gov (United States)

    Gruber, P; Böni, T

    2015-12-01

    In ancient times as well as in the Middle Ages treatment options for discogenic nerve compression syndrome were limited and usually not very specific because of low anatomical and pathophysiological knowledge. The stretch rack (scamnum Hippocratis) was particularly prominent but was widely used as a therapeutic device for very different spinal disorders. Since the beginning of the nineteenth century anatomical knowledge increased and the advances in the fields of asepsis, anesthesia and surgery resulted in an increase in surgical interventions on the spine. In 1908 the first successful lumbar discectomy was initiated and performed by the German neurologist Heinrich O. Oppenheim (1858-1919) and the surgeon Fedor Krause (1857-1937); however, neither recognized the true pathological condition of discogenic nerve compression syndrome. With the landmark report in the New England Journal of Medicine in 1934, the two American surgeons William Jason Mixter (1880-1958) and Joseph Seaton Barr (1901-1963) finally clarified the pathomechanism of lumbar disc herniation and furthermore, propagated discectomy as the standard therapy. Since then interventions on intervertebral discs rapidly increased and the treatment options for lumbar disc surgery quickly evolved. The surgical procedures changed over time and were continuously being refined. In the late 1960s the surgical microscope was introduced for spinal surgery by the work of the famous neurosurgeon Mahmut Gazi Yasargil and his colleague Wolfhard Caspar and so-called microdiscectomy was introduced. Besides open discectomy other interventional techniques were developed to overcome the side effects of surgical procedures. In 1964 the American orthopedic surgeon Lyman Smith (1912-1991) introduced chemonucleolysis, a minimally invasive technique consisting only of a cannula and the proteolytic enzyme chymopapain, which is injected into the disc compartment to dissolve the displaced disc material. In 1975 the Japanese orthopedic

  19. Effect of Pre-Procedural Chair-Side Finger Stretches on Pinch Strength amongst Dental Cohort- A Biomechanical Study.

    Science.gov (United States)

    Padhye, Ninad Milind; Padhye, Ashvini Mukul; Gupta, Himani Swatantrakumar

    2017-04-01

    Ergonomics is the essential principle behind the health and successful practice for a dentist and dental hygienist. During the procedure of dental Scaling and Root Planing (SRP), a high level of pinch force is exerted by the finger muscles resulting in early muscle fatigue. This pilot study comparatively evaluated the Pinch Strength (PS) of the finger muscles, prior to and after SRP, amongst dental cohort performing chair-side hand and finger stretches to those not performing the same. Forty dental professionals were recruited by purposive sampling for the study and allocated into a test and control group. PS was recorded for both groups following which the test group performed finger stretches comprising of rubber band stretch, tendon glide, finger flexion and extension, thumb flexion and finger webbing. The subjects of both the groups carried out SRP for 30 minutes after which PS was again recorded. Inter-group difference was analysed for variability at baseline and 30 minutes after SRP using independent samples/unpaired t-test. Within group comparison of PS measurement was done using paired t-test. The PS for the test group declined from 14.425±2.577 pounds (lbs) to 13.725±2.557 lbs, while for the control group, a decline in PS from 13.65±2.636 lbs to 10.675±2.478 lbs after SRP was noted. On comparing the difference of means of both groups, a statistically significant result was obtained. Work-related musculoskeletal disorders can be reduced by performing a few simple chair-side stretches. These stretches can help prevent the finger muscle fatigue during SRP and thus, increase its efficacy.

  20. Vibrational and orientational dynamics of water in aqueous hydroxide solutions.

    Science.gov (United States)

    Hunger, Johannes; Liu, Liyuan; Tielrooij, Klaas-Jan; Bonn, Mischa; Bakker, Huib

    2011-09-28

    We report the vibrational and orientational dynamics of water molecules in isotopically diluted NaOH and NaOD solutions using polarization-resolved femtosecond vibrational spectroscopy and terahertz time-domain dielectric relaxation measurements. We observe a speed-up of the vibrational relaxation of the O-D stretching vibration of HDO molecules outside the first hydration shell of OH(-) from 1.7 ± 0.2 ps for neat water to 1.0 ± 0.2 ps for a solution of 5 M NaOH in HDO:H(2)O. For the O-H vibration of HDO molecules outside the first hydration shell of OD(-), we observe a similar speed-up from 750 ± 50 fs to 600 ± 50 fs for a solution of 6 M NaOD in HDO:D(2)O. The acceleration of the decay is assigned to fluctuations in the energy levels of the HDO molecules due to charge transfer events and charge fluctuations. The reorientation dynamics of water molecules outside the first hydration shell are observed to show the same time constant of 2.5 ± 0.2 ps as in bulk liquid water, indicating that there is no long range effect of the hydroxide ion on the hydrogen-bond structure of liquid water. The terahertz dielectric relaxation experiments show that the transfer of the hydroxide ion through liquid water involves the simultaneous motion of ~7 surrounding water molecules, considerably less than previously reported for the proton. © 2011 American Institute of Physics

  1. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects.

    LENUS (Irish Health Repository)

    O'Sullivan, Kieran

    2009-01-01

    BACKGROUND: Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. METHODS: A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. RESULTS: Across both groups, there was a significant main effect for time (p < 0.001). PKE ROM significantly increased with warm-up (p < 0.001). From warm-up, PKE ROM further increased with static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p < 0.001) after 15 minutes of rest, but remained significantly greater than at baseline (p < 0.001). Between groups, there was no main effect for group (p = 0.462), with no difference in mean PKE ROM values at any individual stage of the protocol (p > 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05). CONCLUSION: Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced

  2. How to determine the pressure of a methane-containing gas mixture by means of two weak Raman bands, v(3) and 2v(2)

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan

    2002-01-01

    , n3 (asymmetric C-H stretching) and 2n2 (overtone of the asymmetric C-H bending), is observed; the methane n3 band intensity is lowered relative to the methane 2n2 as the pressure is raised. The intensity ratios between these two bands, In3/I2n2, were determined and plotted as a function of pressure...

  3. High-resolution vibrational neutron spectra of collagen

    International Nuclear Information System (INIS)

    Bradshaw, J.; Miller, A.; Robertson, S.T.; Middendorf, H.D.

    1992-01-01

    High-resolution vibrational spectra of oriented D 2 O-exchanged collagen fibres at 20 and 110 K have been measured using the pulsed-neutron spectrometer TFXA at ISIS. Numerous bands between 20 and 3800 cm -1 show a level of fine structure approaching that of optical spectra. The principal features of the spectra observed are discussed in the context of recent work on collagen and related triple-helical polypeptides, and some tentative assignments are made. (orig.)

  4. Intrinsic Chirality and Prochirality at Air/R-(+)- and S-(-)-Limonene Interfaces: Spectral Signatures with Interference Chiral Sum-Frequency Generation Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Li; Zhang, Yun; Wei, Zhehao; Wang, Hongfei

    2014-06-04

    We report in this work detailed measurements on the chiral and achiral sum-frequency vibrational spectra in the C-H stretching vibration region (2800-3050cm-1) of the air/liquid interfaces of R-limonene and S-limonene, using the recently developed high-resolution broadband sum-frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The achiral SFG spectra of R-limonene and S-limonene, as well as the equal amount (50/50) racemic mixture show that the enantiomers are with the same interfacial orientations. The interference chiral SFG spectra of the limonene enantiomers exhibit spectral signature from chiral response of the Cα-H stretching mode, and spectral signature from prochiral response of the CH2 asymmetric stretching mode, respectively. The chiral spectral feature of the Cα-H stretching mode changes sign from R-limonene to S-limonene, and disappears for the 50/50 racemic mixture. While the prochiral spectral feature of the CH2 asymmetric stretching mode is the same for R-limonene and S-limonene, and also surprisingly remains the same for the 50/50 racemic mixture. These results provided detail information in understanding the structure and chirality of molecular interfaces, and demonstrated the sensitivity and potential of SFG-VS as unique spectroscopic tool for chirality characterization and chiral recognition at the molecular interface.

  5. EFFECTIVENESS OF PNF STRETCHING VERSUS STATIC STRETCHING ON PAIN AND HAMSTRING FLEXIBILITY FOLLOWING MOIST HEAT IN INDIVIDUALS WITH KNEE OSTEOARTHRITIS

    OpenAIRE

    Meena .V; Shanthi .C; Madhavi .K

    2016-01-01

    Background: Osteoarthritis (OA) is a degenerative joint disease and one of the major public health problem that causesfunctional impairment and reduced quality of life. To compare the effectiveness of PNF Hold relax stretching versus Static stretching on pain and flexibility of hamstring following moist heat in individuals with knee osteoarthritis. Hamstring tightness is the major problem in knee osteoarthritis individuals. Therefore the need of study is comparing the effectiveness of PNF Hol...

  6. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects

    Directory of Open Access Journals (Sweden)

    Murray Elaine

    2009-04-01

    Full Text Available Abstract Background Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. Methods A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM. 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1 at baseline; (2 after warm-up; (3 after stretch (static or dynamic and (4 after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. Results Across both groups, there was a significant main effect for time (p 0.05. Using ANCOVA to adjust for the non-significant (p = 0.141 baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05. Conclusion Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes. Trial Registration ACTRN12608000638336

  7. Cardiovascular Responses to Skeletal Muscle Stretching: "Stretching" the Truth or a New Exercise Paradigm for Cardiovascular Medicine?

    Science.gov (United States)

    Kruse, Nicholas T; Scheuermann, Barry W

    2017-12-01

    Stretching is commonly prescribed with the intended purpose of increasing range of motion, enhancing muscular coordination, and preventing prolonged immobilization induced by aging or a sedentary lifestyle. Emerging evidence suggests that acute or long-term stretching exercise may modulate a variety of cardiovascular responses. Specifically, at the onset of stretch, the mechanical deformation of the vascular bed coupled with stimulation of group III muscle afferent fibers initiates a cascade of events resulting in both peripheral vasodilation and a heart rate-driven increase in cardiac output, blood pressure, and muscle blood flow. This potential to increase shear stress and blood flow without the use of excessive muscle energy expenditure may hold important implications for future therapeutic vascular medicine and cardiac health. However, the idea that a cardiovascular component may be involved in human skeletal muscle stretching is relatively new. Therefore, the primary intent of this review is to highlight topics related to skeletal muscle stretching and cardiovascular regulation and function. The current evidence suggests that acute stretching causes a significant macro- and microcirculatory event that alters blood flow and the relationship between oxygen availability and oxygen utilization. These acute vascular changes if performed chronically may result in improved endothelial function, improved arterial blood vessel stiffness, and/or reduced blood pressure. Although several mechanisms have been postulated, an increased nitric oxide bioavailability has been highlighted as one promising candidate for the improvement in vessel function with stretching. Collectively, the evidence provided in this review suggests that stretching acutely or long term may serve as a novel and alternative low intensity therapeutic intervention capable of improving several parameters of vascular function.

  8. Photochromism of Composite Organometallic Nanostructures Based on Diarylethenes. II. Vibrational Spectroscopy and Quantum Chemistry Studies

    Science.gov (United States)

    Vasilyuk, G. T.; Askirka, V. F.; Lavysh, A. V.; Kurguzenkov, S. A.; Yasinskii, V. M.; Kobeleva, O. I.; Valova, T. M.; Ayt, A. O.; Barachevsky, V. A.; Yarovenko, V. N.; Krayushkin, M. M.; Maskevich, S. A.

    2017-11-01

    The structure and photochromic transformations of nanostructured organometallic composites consisting of Ag nanoparticles with shells of photochromic diarylethenes (DAEs) deposited from various solutions onto the nanoparticles were studied using infrared absorption and surface enhanced Raman scattering (SERS) vibrational spectroscopy and quantum chemistry. The studied nanostructures exhibited photochromic properties manifested as reversible photoinduced changes of the relative intensities of SERS bands related to vibrations of bonds participating in the reversible photoisomerization. Spectral manifestations of chemical interaction between metal nanoparticles and DAE molecules were detected.

  9. Laparoscopic gastric banding

    Science.gov (United States)

    ... eat by making you feel full after eating small amounts of food. After surgery, your doctor can adjust the band ... You will feel full after eating just a small amount of food. The food in the small upper pouch will ...

  10. Decay of superdeformed bands

    International Nuclear Information System (INIS)

    Carpenter, M.P.; Khoo, T.L.; Lauritsen, T.

    1995-01-01

    One of the major challenges in the study of superdeformation is to directly connect the large number of superdeformed bands now known to the yrast states. In this way, excitation energies, spins and parities can be assigned to the levels in the second well which is essential to establish the collective and single-particle components of these bands. This paper will review some of the progress which has been made to understand the decay of superdeformed bands using the new arrays including the measurement of the total decay spectrum and the establishment of direct one-step decays from the superdeformed band to the yrast line in 194 Hg. 42 refs., 5 figs

  11. HYBASE - HYperspectral BAnd SElection tool

    NARCIS (Netherlands)

    Schwering, P.B.W.; Bekman, H.H.P.T.; Seijen, H.H. van

    2008-01-01

    Band selection is essential in the design of multispectral sensor systems. This paper describes the TNO hyperspectral band selection tool HYBASE. It calculates the optimum band positions given the number of bands and the width of the spectral bands. HYBASE is used to calculate the minimum number of

  12. Localization and stretch-dependence of lung elastase activity in development and compensatory growth.

    Science.gov (United States)

    Young, Sarah Marie; Liu, Sheng; Joshi, Rashika; Batie, Matthew R; Kofron, Matthew; Guo, Jinbang; Woods, Jason C; Varisco, Brian Michael

    2015-04-01

    Synthesis and remodeling of the lung matrix is necessary for primary and compensatory lung growth. Because cyclic negative force is applied to developing lung tissue during the respiratory cycle, we hypothesized that stretch is a critical regulator of lung matrix remodeling. By using quantitative image analysis of whole-lung and whole-lobe elastin in situ zymography images, we demonstrated that elastase activity increased twofold during the alveolar stage of postnatal lung morphogenesis in the mouse. Remodeling was restricted to alveolar walls and ducts and was nearly absent in dense elastin band structures. In the mouse pneumonectomy model of compensatory lung growth, elastase activity increased threefold, peaking at 14 days postpneumonectomy and was higher in the accessory lobe compared with other lobes. Remodeling during normal development and during compensatory lung growth was different with increased major airway and pulmonary arterial remodeling during development but not regeneration, and with homogenous remodeling throughout the parenchyma during development, but increased remodeling only in subpleural regions during compensatory lung growth. Left lung wax plombage prevented increased lung elastin during compensatory lung growth. To test whether the adult lung retains an innate capacity to remodel elastin, we developed a confocal microscope-compatible stretching device. In ex vivo adult mouse lung sections, lung elastase activity increased exponentially with strain and in peripheral regions of lung more than in central regions. Our study demonstrates that lung elastase activity is stretch-dependent and supports a model in which externally applied forces influence the composition, structure, and function of the matrix during periods of alveolar septation. Copyright © 2015 the American Physiological Society.

  13. Effects of Static Stretching and Playing Soccer on Knee Laxity.

    Science.gov (United States)

    Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W; Freiwald, Jürgen

    2015-11-01

    This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Randomized controlled trial. University biomechanics laboratory. Thirty-one athletes were randomly assigned into a stretching (26.9 ± 6.2 years, 1.77 ± 0.09 m, 67.9 ± 10.7 kg) and a control group (27.9 ± 7.4 years, 1.75 ± 0.08 m, 72.0 ± 14.9 kg). Thirty-one amateur soccer players in an additional soccer group (25.1 ± 5.6 years, 1.74 ± 0.10 m, 71.8 ± 14.8 kg). All participants had no history of knee injury requiring surgery and any previous knee ligament or cartilage injury. The stretching group performed 4 different static stretching exercises with a duration of 2 × 20 seconds interspersed with breaks of 10 seconds. The soccer group completed a 90-minute soccer-specific training program. The control group did not perform any physical activity for approximately 30 minutes. Anterior tibial translation was measured with the KT-1000 knee arthrometer at forces of 67 N, 89 N, and maximal manual force (Max) before and after the intervention. There was a significant increase in ATT after static stretching and playing soccer at all applied forces. Maximal manual testing revealed a mean increase of ATT after static stretching of 2.1 ± 1.6 mm (P static stretching at 67 and 89 N is significantly higher than in controls. At maximum manual testing, significant differences were evident between all groups. Static stretching and playing soccer increase ATT and may consequently influence mechanical factors of the anterior cruciate ligament. The ATT increase after static stretching was greater than after playing soccer. The observed increase in ATT after static stretching and playing soccer may be associated with changes in kinesthetic perception and sensorimotor control, activation of muscles, joint stability, overall performance, and higher injury risk.

  14. Determination of the Oscillator Strengths for the Third and Fourth Vibrational Overtone Transitions in Simple Alcohols

    Science.gov (United States)

    Wallberg, Jens; Kjaergaard, Henrik G.

    2017-06-01

    Absolute measurements of the weak transitions require sensitive spectroscopic techniques. With our recently constructed pulsed cavity ring down (CRD) spectrometer, we have recorded the third and fourth vibrational overtone of the OH stretching vibration in a series of simple alcohols: methanol (MeOH), ethanol (EtOH), 1-propanol (1-PrOH), 2-propanol (2-PrOH) and tert-butanol (tBuOH). The CRD setup (in a flow cell configuration) is combined with a conventional FTIR spectrometer to determine the partial pressure of the alcohols from the fundamental transitions of the OH-stretching vibration. The oscillator strengths of the overtone transitions are determined from the integrated absorbances of the overtone spectra and the partial pressures. Furthermore, the oscillator strengths were calculated using vibrational local mode theory with energies and dipole moments calculated at CCSD(T)/aug-cc-pVTZ level of theory. We find a good agreement between the observed and calculated oscillator strengths across the series of alcohols.

  15. Hurricane Spiral Bands.

    Science.gov (United States)

    Guinn, Thomas A.; Schubert, Wayne H.

    1993-10-01

    The spiral bands that occur in tropical cyclones can be conveniently divided into two classes-outer bands and inner bands. Evidence is presented here that the outer bands form as the result of nonlinear effects during the breakdown of the intertropical convergence zone (ITCZ) through barotropic instability. In this process a zonal strip of high potential vorticity (the ITCZ shear zone or monsoon trough) begins to distort in a varicose fashion, with the potential vorticity (PV) becoming pooled in local regions that are connected by filaments of high PV. As the pooled regions become more axisymmetric, the filaments become thinner and begin to wrap around the PV centers.It is argued that inner bands form in a different manner. As a tropical cyclone intensifies due to latent heat release, the PV field becomes nearly circular with the highest values of PV in the cyclone center. The radial gradient of PV provides a state on which PV waves (the generalization of Rossby waves) can propagate. The nonlinear breaking of PV waves then leads to an irreversible distortion of the PV contours and a downgradient flux of PV. The continuation of this proem tends to erode the high PV core of the tropical cyclone, to produce a surrounding surf zone, and hence to spread the PV horizontally. In a similar fashion, inner bands can also form by the merger of a vortex with a patch of relatively high PV air. As the merger proem occurs the patch of PV is quickly elongated and wrapped around the vortex. The resulting vortex is generally larger in horizontal extent and exhibits a spiral band of PV.When the formation of outer and inner bands is interpreted in the context of a normal-mode spectral model, they emerge as slow manifold phenomena; that is, they have both rotational and (balanced or slaved) gravitational mode aspects. In this sense, regarding them as simply gravity waves leads to an incomplete dynamical picture.

  16. Observation of the a_1 CH Stretching Modes of Phenyl Radical

    Science.gov (United States)

    Chang, Chih-Hsuan; Buckingham, Grant T.; Nesbitt, David J.

    2013-06-01

    High resolution spectroscopy for infrared rovibrational transitions in the CH stretching manifold of phenyl radical (C_6H_5) has been investigated in the slit-jet supersonic expansion at sub-Doppler resolution (60 MHz). Two new fundamental modes are observed and analyzed in this present study, corresponding to b-type structure originating from excitation of the fundamentals v_1 and v_2 mode. The band origins are determined to be 3073.96850(8) cm^{-1} and 3062.26480(7) cm^{-1}, respectively, which agree well with theoretical anharmonic scaling prediction within 5 cm^{-1} based on the B3LYP/6-311g++(3df,3dp) basis set, but shifted by 11 cm^{-1} from the corresponding experimental Ar-matrix's results of Ellison and coworkers. Intensities for the three bands are also analyzed, with the relative intensities between these three agreeing well with theoretical calculation. The physical interpretation of the inertia defect and perturbations of the band positions to explain the experimental observation and the frequencies shift. Anders. V. Friderichsen, Juliusz G. Radziszewski, Mark R. Nimols, Paul R. Winter, David C. Dayton, Donald E. David, and G. Barney Ellison, J. Am. Chem. Soc. 123, 1977 (2001)

  17. Vibrational Stark effect of the electric-field reporter 4-mercaptobenzonitrile as a tool for investigating electrostatics at electrode/SAM/solution interfaces

    NARCIS (Netherlands)

    Schkolnik, G.; Salewski, J.; Millo, D.; Zebger, I.; Franzen, S.; Hildebrandt, P.

    2012-01-01

    4-mercaptobenzonitrile (MBN) in self-assembled monolayers (SAMs) on Au and Ag electrodes was studied by surface enhanced infrared absorption and Raman spectroscopy, to correlate the nitrile stretching frequency with the local electric field exploiting the vibrational Stark effect (VSE). Using MBN

  18. Random vibrations theory and practice

    CERN Document Server

    Wirsching, Paul H; Ortiz, Keith

    1995-01-01

    Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...

  19. High-resolution synchrotron infrared spectroscopy of acrolein: The vibrational levels between 850 and 1020 cm-1

    Science.gov (United States)

    McKellar, A. R. W.; Billinghurst, B. E.; Xu, Li-Hong; Lees, R. M.

    2015-11-01

    Using spectra obtained at the Canadian Light Source synchrotron radiation facility, a previously unobserved out-of-plane vibration of trans-acrolein (propenal) is reliably assigned for the first time. Its origin is at 1002.01 cm-1, which is about 20 cm-1 higher than usually quoted in the past. This mode is thus labelled as v14, leaving the label v15 for the known vibration at 992.66 cm-1. Weak combination bands 171182 ← 182, 171131 ← 131, 121182 ← 181, and 171182 ← 181 are studied for the first time, and assignments in the known v11, v16, and v15 fundamental bands are also extended. The seven excited vibrations involved in these bands are analyzed, together with five more unobserved vibrations in the same region (850-1020 cm-1), in a large 12-state simultaneous fit which accounts for most of the many observed perturbations in the spectra.

  20. First principles investigation of the electronic, elastic and vibrational properties of tungsten disilicide

    International Nuclear Information System (INIS)

    Briquet, Ludovic G.V.; Philipp, Patrick

    2013-01-01

    Highlights: ► Full electronic structure description. ► Elastic properties. ► Phonon band structure and DOS. ► Analysis of vibration modes. -- Abstract: Interest in tungsten disilicide is growing due to its use as protective coatings and non-volatile memory devices but fundamental investigations on tungsten disilicide vibrational properties are lacking in literature. In particular, the phonon vibration modes have never been described. This paper presents a first-principles investigation of the vibrational properties of WSi 2 crystals. The elastic and electronic properties are considered as well. First, the electron band structure is computed. Extra electronic levels for the valence electrons as compared to previously published results are found, highlighting the need for state-of-the-art DFT calculations. It is shown that the ionicity plays only a little role in the W–Si bonding. Instead, a strong degree of covalency is found. The elastic constants are computed in good agreement with the available experimental data. The complete phonon density of state as well as band structure are presented and all vibration modes are described. The phonon vibrations are also correlated to IR and Raman investigations available in the literature

  1. Vibration Mode Observation of Piezoelectric Disk-type Resonator by High Frequency Laser Doppler Vibrometer

    Science.gov (United States)

    Matsumura, Takeshi; Esashi, Masayoshi; Harada, Hiroshi; Tanaka, Shuji

    For future mobile phones based on cognitive radio technology, a compact multi-band RF front-end architecture is strongly required and an integrated multi-band RF filter bank is a key component in it. Contour-mode resonators are receiving increased attention for a multi-band filter solution, because its resonant frequency is mainly determined by its size and shape, which are defined by lithography. However, spurious responses including flexural vibration are also excited due to its thin structure. To improve resonator performance and suppress spurious modes, visual observation with a laser probe system is very effective. In this paper, we have prototyped a mechanically-coupled disk-array filter, which consists of a Si disk and 2 disk-type resonators of higher-order wine-glass mode, and observed its vibration modes using a high-frequency laser-Doppler vibrometer (UHF-120, Polytec, Inc.). As a result, it was confirmed that higher order wine-glass mode vibration included a compound displacement, and that its out-of-plane vibration amplitude was much smaller than other flexural spurious modes. The observed vibration modes were compared with FEM (Finite Element Method) simulation results. In addition, it was also confirmed that the fabrication error, e.g. miss-alignment, induced asymmetric vibration.

  2. Stretched-State Excitations with the

    Science.gov (United States)

    Garcia, Luis Alberto Casimiro

    Neutron time-of-fight spectra were obtained for the ^{14}C(p,n) ^{14}N, ^{18 }O(p,n)^{18}F, and ^{30}Si(p,n) ^{30}P reactions at 135 MeV with the beam-swinger system at the Indiana University Cyclotron Facility. Excitation-energy spectra and the differential cross sections for the observed excitations in these reactions were extracted over the momentum transfer range from 0 to 2.7 fm^{-1}. The primary goal of this work was to obtain the strengths and distributions for the "stretched" states. The identification of these states was based on comparisons of the theoretical differential cross sections, performed in a DWIA formalism, with the experimental cross sections. Isospin assignments were based primarily on comparisons of the measured (p,n) and (e,e^') spectroscopic strengths. Candidate (pid_ {5/2},nu{rm p}_sp {3/2}{-1}), J^ pi = 4 ^- T = 0, 1 and 2, 1 hbaromega states, were identified at E_{x} = 8.5, 13.8, 19.5, and 26.7 MeV in the ^{14}C(p,n) ^{14}N reaction, and the corresponding isovector strengths were extracted. The observed 4^--state excitation energies and the strengths are in good agreement with the analog T = 1 and 2, 4^--states observed in the (e,e^') reaction. Large -basis shell-model calculations were found to predict reasonably well the excitation energies; however, these calculations overpredict the strength by a factor of 2, for the T = 1 and 2 components. In the ^{18}O(p,n) ^{18}F reaction at 135 MeV, (pi d_{5/2},nu {rm d}_sp{5/2}{-1 }) 5^+ T = 0 0hbaromega strength was observed, concentrated in a single state, at E_{x} = 1.1 MeV, with 75% of the extreme-single-particle-model (ESPM) strength, in good agreement with a shell-model calculation. No 6^- 1hbaromega strength was observed in this reaction. Candidate (pi {rm d}_{5/2},nu p _sp{3/2}{-1}) J ^pi = 4^- T = 0, 1 and 2, 1hbaromega states, were identified at E_{x} = 3.9, 9.4, 10.2, 11.4, 12.0, 14.4, 15.3, 17.3, 18.0, 19.7, 21.4, and 23.4 MeV. The observed 4^- T = 2 state excitation energies and

  3. Stability and vibrations control of a stepped beam using piezoelectric actuation

    Directory of Open Access Journals (Sweden)

    Kuliński Krzysztof

    2018-01-01

    Full Text Available The objects of this studies are the stability and transversal vibrations of the system composed of three segments, where in the centre part of the system two piezoelectric patches are perfectly bonded to the top and bottom surface of the host beam. The system is kinematically loaded as a result of prescribed displacement of one or both end supports. For the analysis purposes three different beam end supports have been taken into consideration, which prevent longitudinal displacements i.e. clamped-clamped, clamped-pinned and pinned-pinned. This type of beam loading not only affect its natural vibration frequencies but also the system’s stability. By introducing the electric field to the piezo patches, depending on its vector direction, in-plane stretching or compressive residual force may be induced. Presented results show that piezo actuation can significantly modify both the critical buckling force and the vibration frequency.

  4. Millimeter and submillimeter wave spectroscopy of HNC and DNC in the vibrationally excited states

    Science.gov (United States)

    Okabayashi, Toshiaki; Tanimoto, Mitsutoshi

    1993-09-01

    The rotational transitions of hydrogen isocyanide (HNC) and deuterium isocyanide (DNC) in the vibrationally excited states as well as in the ground states were observed in the millimeter and submillimeter wave region. These compounds were generated in a dc glow discharge plasma containing hydrogen (or deuterium), nitrogen, and carbon atoms. The stretching vibrational modes, nu1 and nu3 states, were selectively excited in the discharge plasma; on the other hand, the bending mode nu2 state was thermally populated at the cell temperature. The precise rotational, centrifugal distortion and l-type doubling constants were obtained for all of the first vibrationally excited states as well as the ground states. The experimental equilibrium rotational constants Be are 45 496.7769(45) and 38 207.7217(105) MHz for HNC and DNC, respectively, where uncertainties correspond to one standard deviation. The equilibrium internuclear distances are also determined.

  5. Effects of two vibrational modes in the dissociative electron attachment to CF3Cl

    International Nuclear Information System (INIS)

    Tarana, Michal; Wielgus, Pawel; Roszak, Szczepan; Fabrikant, Ilya I.

    2009-01-01

    We present a study of multimode effects in dissociative electron attachment to CF 3 Cl molecules using a time-independent version of the local complex potential theory. Symmetric stretch C-Cl vibrations ν 3 and symmetric deformation (or so-called umbrella) vibrations ν 2 are included. The neutral and anion potential energy surfaces are calculated using the second-order Moeller-Plesset perturbation theory with an empirical adjustment of the vertical attachment energy. The final-state vibrational distribution in the CF 3 (ν 2 ) fragment is dominated by the ν 2 =2 state. We also find an increase in the total cross section as compared with the one-dimensional calculations. This is explained by an increase in the anion survival probability.

  6. Clamped seismic metamaterials: ultra-low frequency stop bands

    Science.gov (United States)

    Achaoui, Y.; Antonakakis, T.; Brûlé, S.; Craster, R. V.; Enoch, S.; Guenneau, S.

    2017-06-01

    The regularity of earthquakes, their destructive power, and the nuisance of ground vibration in urban environments, all motivate designs of defence structures to lessen the impact of seismic and ground vibration waves on buildings. Low frequency waves, in the range 1-10 Hz for earthquakes and up to a few tens of Hz for vibrations generated by human activities, cause a large amount of damage, or inconvenience; depending on the geological conditions they can travel considerable distances and may match the resonant fundamental frequency of buildings. The ultimate aim of any seismic metamaterial, or any other seismic shield, is to protect over this entire range of frequencies; the long wavelengths involved, and low frequency, have meant this has been unachievable to date. Notably this is scalable and the effects also hold for smaller devices in ultrasonics. There are three approaches to obtaining shielding effects: bragg scattering, locally resonant sub-wavelength inclusions and zero-frequency stop-band media. The former two have been explored, but the latter has not and is examined here. Elastic flexural waves, applicable in the mechanical vibrations of thin elastic plates, can be designed to have a broad zero-frequency stop-band using a periodic array of very small clamped circles. Inspired by this experimental and theoretical observation, all be it in a situation far removed from seismic waves, we demonstrate that it is possible to achieve elastic surface (Rayleigh) wave reflectors at very large wavelengths in structured soils modelled as a fully elastic layer periodically clamped to bedrock. We identify zero frequency stop-bands that only exist in the limit of columns of concrete clamped at their base to the bedrock. In a realistic configuration of a sedimentary basin 15 m deep we observe a zero frequency stop-band covering a broad frequency range of 0-30 Hz.

  7. Neural effects of muscle stretching on the spinal reflexes in multiple lower-limb muscles.

    Science.gov (United States)

    Masugi, Yohei; Obata, Hiroki; Inoue, Daisuke; Kawashima, Noritaka; Nakazawa, Kimitaka

    2017-01-01

    While previous studies have shown that muscle stretching suppresses monosynaptic spinal reflex excitability in stretched muscles, its effects on non-stretched muscles is still largely unknown. The purpose of this study was to examine the effects of muscle stretching on monosynaptic spinal reflex in non-stretched muscles. Ten healthy male subjects participated in this study. Muscle stretching of the right triceps surae muscle was performed using a motor torque device for 1 minute. Three different dorsiflexion torques (at approximately 5, 10, and 15 Nm) were applied during muscle stretching. Spinal reflexes evoked by transcutaneous spinal cord stimulation were recorded in both the lower-limb muscles before, during, and at 0 and 5 min following muscle stretching. The amplitudes of the spinal reflexes in both the stretched and non-stretched muscles in the right (ipsilateral) leg were smaller during stretching compared to before, and at 0 and 5 min after stretching. Furthermore, the degree of reduction in the amplitude of the spinal reflexes in the right (ipsilateral) leg muscles increased significantly as the dorsiflexion torque (i.e., stretching of the right triceps surae muscles) increased. In contrast, reduction in the amplitude of the spinal reflexes with increasing dorsiflexion torque was not seen in the left (contralateral) leg muscles. Our results clearly indicate that muscle stretching has inhibitory effects on monosynaptic spinal reflexes, not only in stretched muscles, but also in non-stretched muscles of the ipsilateral leg.

  8. Electrical characterization, phase transition and vibrational spectroscopic investigations of a new organic-inorganic material (C7H10NO)SnCl3

    Science.gov (United States)

    Karoui, Sahel; Chouaib, Hassen; Kamoun, Slaheddine

    2017-10-01

    The X-ray powder analysis, thermogravimetric analysis, differential scanning calorimetry analysis, solid CP-MAS 13C NMR characterization, vibrational spectroscopy and complex impedance spectroscopic data have been carried out on (C7H10NO)SnCl3 compound. The results show that this compound exhibits a phase transition at 314 K which was characterized by 1H NMR between 298 and 336 K, differential scanning calorimetry (DSC), X-rays powder diffraction, Raman spectroscopy and dielectric measurements. The temperature dependence of the 1H NMR spectrum for (C7H10NO)SnCl3 could be explained by invoking reorientation of ammonium group of the 2-methoxyanilinium cation. The most important changes are observed for two lines at 3087 cm-1 and 3175 cm-1 (at room temperature) issued from asymmetric and symmetric stretching vibrations of νs(NH3) and νas(NH3) band, respectively. AC and DC conductivities, complex dielectric permittivity ε*(ω) and complex electrical modulus M*(ω) were respectively studied as temperature and frequency functions. Moreover, the temperature dependence of the DC conductivity and relaxation frequency followed the Arrhenius relation. The frequency dependence of the real part of the AC conductivity in both phases follows the Jonscher's universal dynamic law: σTot.(ω,T) = σDC(T) + B(T) ωS(T). The close values of activation energies, obtained from the thermal behavior of the conductivity and the relaxation time confirm that the transport is through ion-hopping mechanism.

  9. Identification of the best DFT functionals for a reliable prediction of lignin vibrational properties

    DEFF Research Database (Denmark)

    Barsberg, Soren

    2015-01-01

    Lignin is the most abundant aromatic plant polymer on earth. Useful information on its structure and interactions is gained by vibrational spectroscopy and relies on the quality of band assignments. B3LYP predictions were recently shown to support band assignments. Further progress calls for a co......Lignin is the most abundant aromatic plant polymer on earth. Useful information on its structure and interactions is gained by vibrational spectroscopy and relies on the quality of band assignments. B3LYP predictions were recently shown to support band assignments. Further progress calls...... for a comprehensive study of the quality of available theoretical methods in relation to the task of predicting lignin vibrational properties. The present study examined more than 50 functionals for prediction of IR vibrations of an appropriate lignin model. Based on a basis set incompleteness study, the pc-2 basis...... functional stands out. These results provide a needed basis for further theoretical developments in relation to vibrational assignments of Infrared and Raman spectra of lignin....

  10. Vibration sensitivity of human muscle spindles and Golgi tendon organs.

    Science.gov (United States)

    Fallon, James B; Macefield, Vaughan G

    2007-07-01

    The responses of the various muscle receptors to vibration are more complicated than a naïve categorization into stretch (muscle spindle primary ending), length (muscle spindle secondary endings), and tension (Golgi tendon organs) receptors. To emphasize the similarity of responses to small length changes, we recorded from 58 individual muscle afferents subserving receptors in the ankle or toe dorsiflexors of awake human subjects (32 primary endings, 20 secondary endings, and six Golgi tendon organs). Transverse sinusoidal vibration was applied to the distal tendon of the receptor-bearing muscle, while subjects either remained completely relaxed or maintained a weak isometric contraction of the appropriate muscle. In relaxed muscle, few units responded in a 1:1 manner to vibration, and there was no evidence of a preferred frequency of activation. In active muscle the response profiles of all three receptor types overlapped, with no significant difference in threshold between receptor types. These results emphasize that when intramuscular tension increases during a voluntary contraction, Golgi tendon organs and muscle spindle secondary endings, not just muscle spindle primary endings, can effectively encode small imposed length changes.

  11. Fourth-Order Vibrational Transition State Theory and Chemical Kinetics

    Science.gov (United States)

    Stanton, John F.; Matthews, Devin A.; Gong, Justin Z.

    2015-06-01

    Second-order vibrational perturbation theory (VPT2) is an enormously successful and well-established theory for treating anharmonic effects on the vibrational levels of semi-rigid molecules. Partially as a consequence of the fact that the theory is exact for the Morse potential (which provides an appropriate qualitative model for stretching anharmonicity), VPT2 calculations for such systems with appropriate ab initio potential functions tend to give fundamental and overtone levels that fall within a handful of wavenumbers of experimentally measured positions. As a consequence, the next non-vanishing level of perturbation theory -- VPT4 -- offers only slight improvements over VPT2 and is not practical for most calculations since it requires information about force constants up through sextic. However, VPT4 (as well as VPT2) can be used for other applications such as the next vibrational correction to rotational constants (the ``gammas'') and other spectroscopic parameters. In addition, the marriage of VPT with the semi-classical transition state theory of Miller (SCTST) has recently proven to be a powerful and accurate treatment for chemical kinetics. In this talk, VPT4-based SCTST tunneling probabilities and cumulative reaction probabilities are give for the first time for selected low-dimensional model systems. The prospects for VPT4, both practical and intrinsic, will also be discussed.

  12. Magnetorheological elastomer vibration isolation of tunable three-dimensional locally resonant acoustic metamaterial

    Science.gov (United States)

    Xu, Zhenlong; Tong, Jie; Wu, Fugen

    2018-03-01

    Magnetorheological elastomers (MREs) are used as cladding in three-dimensional locally resonant acoustic metamaterial (LRAM) cores. The metamaterial units are combined into a vibration isolator. Two types of LRAMs, namely, cubic and spherical kernels, are constructed. The finite element method is used to analyze the elastic band structures, transmittances, and vibration modes of the incident elastic waves. Results show that the central position and width of the LRAM elastic bandgap can be controlled by the application of an external magnetic field; furthermore, they can be adjusted by changing the MRE cladding thickness. These methods contribute to the design of metamaterial MRE vibration isolators.

  13. The Possible Interstellar Anion CH2CN-: Spectroscopic Constants, Vibrational Frequencies, and Other Considerations

    Science.gov (United States)

    Fortenberry, Ryan C.; Crawford, T. Daniel; Lee, Timothy J.

    2012-01-01

    The A 1B1 interstellar band. However, this particular molecular system has not been detected in the interstellar medium even though the related cyanomethyl radical and the isoelectronic ketenimine molecule have been found. In this study we are employing the use of proven quartic force elds and second-order vibrational perturbation theory to compute accurate spectroscopic constants and fundamental vibrational frequencies for X 1A0 CH2CN?? in order to assist in laboratory studies and astronomical observations. Keywords: Astrochemistry, ISM: molecular anions, Quartic force elds, Rotational constants, Vibrational frequencies

  14. State preparation and excited electronic and vibrational behavior in hemes.

    Science.gov (United States)

    Challa, J Reddy; Gunaratne, Tissa C; Simpson, M Cather

    2006-10-12

    The temporally overlapping, ultrafast electronic and vibrational dynamics of a model five-coordinate, high-spin heme in a nominally isotropic solvent environment has been studied for the first time with three complementary ultrafast techniques: transient absorption, time-resolved resonance Raman Stokes, and time-resolved resonance Raman anti-Stokes spectroscopies. Vibrational dynamics associated with an evolving ground-state species dominate the observations. Excitation into the blue side of the Soret band led to very rapid S2 --> S1 decay (sub-100 fs), followed by somewhat slower (800 fs) S1 --> S0 nonradiative decay. The initial vibrationally excited, non-Boltzmann S0 state was modeled as shifted to lower energy by 300 cm(-1) and broadened by 20%. On a approximately 10 ps time scale, the S0 state evolved into its room-temperature, thermal distribution S0 profile largely through VER. Anti-Stokes signals disappear very rapidly, indicating that the vibrational energy redistributes internally in about 1-3 ps from the initial accepting modes associated with S1 --> S0 internal conversion to the rest of the macrocycle. Comparisons of anti-Stokes mode intensities and lifetimes from TRARRS studies in which the initial excited state was prepared by ligand photolysis [Mizutani, T.; Kitagawa, T. Science 1997, 278, 443, and Chem. Rec. 2001, 1, 258] suggest that, while transient absorption studies appear to be relatively insensitive to initial preparation of the electronic excited state, the subsequent vibrational dynamics are not. Direct, time-resolved evaluation of vibrational lifetimes provides insight into fast internal conversion in hemes and the pathways of subsequent vibrational energy flow in the ground state. The overall similarity of the model heme electronic dynamics to those of biological systems may be a sign that the protein's influence upon the dynamics of the heme active site is rather subtle.

  15. A periodic piezoelectric smart structure with the integrated passive/active vibration-reduction performances

    Science.gov (United States)

    Wang, Yuxi; Niu, Shengkai; Hu, Yuantai

    2017-06-01

    The paper proposes a new piezoelectric smart structure with the integrated passive/active vibration-reduction performances, which is made of a series of periodic structural units. Every structural unit is made of two layers, one is an array of piezoelectric bimorphs (PBs) and one is an array of metal beams (MBs), both are connected as a whole by a metal plate. Analyses show that such a periodic smart structure possesses two aspects of vibration-reduction performance: one comes from its phonon crystal characteristics which can isolate those vibrations with the driving frequency inside the band gap(s). The other one comes from the electromechanical conversion of bent PBs, which is actively aimed at those vibrations with the driving frequency outside the band gap(s). By adjusting external inductance, the equivalent circuit of the proposed structure can be forced into parallel resonance such that most of the vibration energy is converted into electrical energy for dissipation by a resistance. Thus, an external circuit under the parallel resonance state is equivalent to a strong damping to the interrelated vibrating structure, which is just the action mechanism of the active vibration reduction performance of the proposed smart structure.

  16. Structure-dependent vibrational dynamics of Mg(BH 4 ) 2 polymorphs probed with neutron vibrational spectroscopy and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrievska, Mirjana; White, James L.; Zhou, Wei; Stavila, Vitalie; Klebanoff, Leonard E.; Udovic, Terrence J.

    2016-01-01

    The structure-dependent vibrational properties of different Mg(BH4)2 polymorphs (..alpha.., ..beta.., ..gamma.., and ..delta.. phases) were investigated with a combination of neutron vibrational spectroscopy (NVS) measurements and density functional theory (DFT) calculations, with emphasis placed on the effects of the local structure and orientation of the BH4- anions. DFT simulations closely match the neutron vibrational spectra. The main bands in the low-energy region (20-80 meV) are associated with the BH4- librational modes. The features in the intermediate energy region (80-120 meV) are attributed to overtones and combination bands arising from the lower-energy modes. The features in the high-energy region (120-200 meV) correspond to the BH4- symmetric and asymmetric bending vibrations, of which four peaks located at 140, 142, 160, and 172 meV are especially intense. There are noticeable intensity distribution variations in the vibrational bands for different polymorphs. This is explained by the differences in the spatial distribution of BH4- anions within various structures. An example of the possible identification of products after the hydrogenation of MgB2, using NVS measurements, is presented. These results provide fundamental insights of benefit to researchers currently studying these promising hydrogen-storage materials.

  17. Lattice Vibrations in Chlorobenzenes:

    DEFF Research Database (Denmark)

    Reynolds, P. A.; Kjems, Jørgen; White, J. W.

    1974-01-01

    Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p‐C6D4Cl2 and p‐C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K...... was applied in order to correct for anharmonic effects. Calculations based on the atom‐atom model for van der Waals' interaction and on general potential parameters for the aromatic compounds agree reasonably well with the experimental observations. There is no substantial improvement in fit obtained either...

  18. Digital analysis of vibrations

    International Nuclear Information System (INIS)

    Bohnstedt, H.J.; Walter, G.

    1982-01-01

    Vibrational measurements, e.g. on turbomachinery, can be evaluated rapidly and economically with the aid of a combination of the following instruments: a desk-top computer, a two-channel vector filter and a FFT spectral analyzer. This equipment combination is available within the Allianz Centre for Technology and has also been used for mobile, on-site investigations during the last year. It enables calculation and display of time functions, kinetic shaft orbits, displacement diagrams. Bode plots, polar-coordinate plots, cascade diagrams and histograms. (orig.) [de

  19. Characterization of polymer surface structure and surface mechanical behaviour by sum frequency generation surface vibrational spectroscopy and atomic force microscopy

    International Nuclear Information System (INIS)

    Opdahl, Aric; Koffas, Telly S; Amitay-Sadovsky, Ella; Kim, Joonyeong; Somorjai, Gabor A

    2004-01-01

    Sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM) have been used to study polymer surface structure and surface mechanical behaviour, specifically to study the relationships between the surface properties of polymers and their bulk compositions and the environment to which the polymer is exposed. The combination of SFG surface vibrational spectroscopy and AFM has been used to study surface segregation behaviour of polyolefin blends at the polymer/air and polymer/solid interfaces. SFG surface vibrational spectroscopy and AFM experiments have also been performed to characterize the properties of polymer/liquid and polymer/polymer interfaces, focusing on hydrogel materials. A method was developed to study the surface properties of hydrogel contact lens materials at various hydration conditions. Finally, the effect of mechanical stretching on the surface composition and surface mechanical behaviour of phase-separated polyurethanes, used in biomedical implant devices, has been studied by both SFG surface vibrational spectroscopy and AFM. (topical review)

  20. Cyclic Stretch Alters Vascular Reactivity of Mouse Aortic Segments

    Directory of Open Access Journals (Sweden)

    Arthur Leloup

    2017-10-01

    Full Text Available Large, elastic arteries buffer the pressure wave originating in the left ventricle and are constantly exposed to higher amplitudes of cyclic stretch (10% than muscular arteries (2%. As a crucial factor for endothelial and smooth muscle cell function, cyclic stretch has, however, never been studied in ex vivo aortic segments of mice. To investigate the effects of cyclic stretch on vaso-reactivity of mouse aortic segments, we used the Rodent Oscillatory Tension Set-up to study Arterial Compliance (ROTSAC. The aortic segments were clamped at frequencies of 6–600 bpm between two variable preloads, thereby mimicking dilation as upon left ventricular systole and recoiling as during diastole. The preloads corresponding to different transmural pressures were chosen to correspond to a low, normal or high amplitude of cyclic stretch. At different time intervals, cyclic stretch was interrupted, the segments were afterloaded and isometric contractions by α1-adrenergic stimulation with 2 μM phenylephrine in the absence and presence of 300 μM L-NAME (eNOS inhibitor and/or 35 μM diltiazem (blocker of voltage-gated Ca2+ channels were measured. As compared with static or cyclic stretch at low amplitude (<10 mN or low frequency (0.1 Hz, cyclic stretch at physiological amplitude (>10 mN and frequency (1–10 Hz caused better ex vivo conservation of basal NO release with time after mounting. The relaxation of PE-precontracted segments by addition of ACh to stimulate NO release was unaffected by cyclic stretch. In the absence of basal NO release (hence, presence of L-NAME, physiological in comparison with aberrant cyclic stretch decreased the baseline tension, attenuated the phasic contraction by phenylephrine in the absence of extracellular Ca2+ and shifted the smaller tonic contraction more from a voltage-gated Ca2+ channel-mediated to a non-selective cation channel-mediated. Data highlight the need of sufficient mechanical activation of endothelial and

  1. Measurement of skin stretch using digital image speckle correlation.

    Science.gov (United States)

    Staloff, Isabelle Afriat; Rafailovitch, Miriam

    2008-08-01

    The surface of the skin is covered by intersecting grooves and ridges which produce characteristic skin surface patterns. It has been suggested that these folds provide a reserve of tissue, allowing the skin to stretch during normal muscle movements. More so, skin is anisotropic and under constant tension. Therefore, to characterize skin displacement following stretch, a discrete, description of the in-plane skin displacement during stretch is of interest. We introduce the use of digital image speckle correlation (DISC), a non-contact technique, to map, in two dimensions, the surface deformation patterns resulting from skin stretching. We analyze skin stretch under the mechanical action of a film former applied on a defined square surface on the back of the hand. This is achieved by taking a series of images, during the drying process of the film former. The images are then analyzed with DISC to create vector diagram and projection maps, from which we can obtain spatially resolved information regarding the skin displacement. We first show that DISC can provide spatially resolved information at any time point during the drying process: areas of de-wetting, wetting were identified using projection maps; we then extracted the value of the drying time. Finally using a vector map, we show the orientation of the skin displacement during stretching and calculated the magnitude of the total stretch. We have shown previously that DISC can be used to determine skin mechanical properties and muscular activity. We show here that DISC, as a non-contact technique, can map, in two dimensions, the surface deformation patterns of a polymer solution on a substrate at any time point during the drying process. DISC analysis generates for each speckle of the sample analyzed, the orientation and magnitude of displacement of the polymer solution. DISC can map in two dimensions the deformation undergone by the substrate and skin stretch is measured in this particular case. We therefore

  2. Quantum dynamics of vibrational excitations and vibrational charge ...

    Indian Academy of Sciences (India)

    Administrator

    Dedicated to the memory of the late Professor S K Rangarajan. *For correspondence. Quantum dynamics of vibrational excitations and vibrational charge transfer processes in H. +. + O2 collisions at collision energy 23 eV. †. SAIESWARI AMARAN# and SANJAY KUMAR*. Department of Chemistry, Indian Institute of ...

  3. Off-axis Modal Active Vibration Control Of Rotational Vibrations

    NARCIS (Netherlands)

    Babakhani, B.; de Vries, Theodorus J.A.; van Amerongen, J.

    Collocated active vibration control is an effective and robustly stable way of adding damping to the performance limiting vibrations of a plant. Besides the physical parameters of the Active Damping Unit (ADU) containing the collocated actuator and sensor, its location with respect to the

  4. Photonic band gap materials

    Science.gov (United States)

    Cassagne, D.

    Photonic band gap materials Photonic band gap materials are periodic dielectric structures that control the propagation of electromagnetic waves. We describe the plane wave method, which allows to calculate the band structures of photonic crystals. By symmetry analysis and a perturbative approach, we predict the appearance of the low energy photonic band gaps of hexagonal structures. We propose new two-dimensional structures called graphite and boron nitride. Using a transfer matrix method, we calculate the transmission of the graphite structure and we show the crucial role of the coupling with external modes. We study the appearance of allowed modes in the photonic band gap by the introduction of localized defects in the periodicity. Finally, we discuss the properties of opals formed by self-organized silica microspheres, which are very promising for the fabrication of three-dimensional photonic crystals. Les matériaux à bandes interdites photoniques sont des structures diélectriques périodiques qui contrôlent la propagation des ondes électromagnétiques. Nous décrivons la méthode des ondes planes qui permet de calculer les structures de bandes des cristaux photoniques. Par une analyse de la symétrie et une approche perturbative, nous précisons les conditions d'existence des bandes interdites de basse énergie. Nous proposons de nouvelles structures bidimensionnelles appelées graphite et nitrure de bore. Grâce à une méthode de matrices de transfert, nous calculons la transmission de la structure graphite et nous mettons en évidence le rôle fondamental du couplage avec les modes extérieurs. Nous étudions l'apparition de modes permis dans la bande interdite grâce à l'introduction de défauts dans la périodicité. Enfin, nous discutons les propriétés des opales constituées de micro-billes de silice auto-organisées, qui sont très prometteuses pour la fabrication de cristaux photoniques tridimensionnels.

  5. Extracting local stretching from left ventricle angiography data

    Science.gov (United States)

    Mishra, Sanjoy K.; Goldgof, Dmitry B.

    1991-07-01

    This paper presents a new method for extracting local surface stretching from the left ventricle (LV) cineangiography data. The algorithm is based on Gaussian curvature for surface stretching recovery under more realistic conformal motion assumption. During conformal motion surface stretching can vary over the surface patch. In particular, surface stretching can be approximated using linear or quadratic (or higher order) functions. Then, coefficients of the approximating function can be calculated and surface stretching computed from changes in surface curvature at corresponding points. For example, linear approximation requires three point correspondences (between consecutive time frames) within small surface patch. The authors demonstrate the higher precision of the new approach (as compared to homothetic assumption in the authors' earlier work) on simulated and real data of the left ventricle of the human heart. The data set was provided by Dr. Alistair Young of the University of Auckland, New Zealand, and consists of the tracked locations of eleven bifurcation points of the left coronary artery and the tracked locations of 292 vessel points for one cardiac cycle (60 frames/cycle).

  6. Controlled cyclic stretch bioreactor for tissue-engineered heart valves.

    Science.gov (United States)

    Syedain, Zeeshan H; Tranquillo, Robert T

    2009-09-01

    A tissue-engineered heart valve (TEHV) represents the ultimate valve replacement, especially for juvenile patients given its growth potential. To date, most TEHV bioreactors have been developed based on pulsed flow of culture medium through the valve lumen to induce strain in the leaflets. Using a strategy for controlled cyclic stretching of tubular constructs reported previously, we developed a controlled cyclic stretch bioreactor for TEHVs that leads to improved tensile and compositional properties. The TEHV is mounted inside a latex tube, which is then cyclically pressurized with culture medium. The root and leaflets stretch commensurately with the latex, the stretching being dictated by the stiffer latex and thus controllable. Medium is also perfused through the lumen at a slow rate in a flow loop to provide nutrient delivery. Fibrin-based TEHVs prepared with human dermal fibroblasts were subjected to three weeks of cyclic stretching with incrementally increasing strain amplitude. The TEHV possessed the tensile stiffness and stiffness anisotropy of leaflets from sheep pulmonary valves and could withstand cyclic pulmonary pressures with similar distension as for a sheep pulmonary artery.

  7. Influence of chronic stretching on muscle performance: Systematic review.

    Science.gov (United States)

    Medeiros, D M; Lima, C S

    2017-08-01

    The aim of the current study was to investigate the influence of chronic stretching on muscle performance (MP) by a systematic review. The search strategy included MEDLINE, PEDro, Cochrane CENTRAL, LILACS, and manual search from inception to June 2016. Randomized and controlled clinical trials, non-randomized, and single group studies that have analyzed the influence of flexibility training (FT) (using any stretching technique) on MP were included. Differently, studies with special populations (children, elderly, and people with any dysfunction/disease), and articles that have used FT protocols shorter than three weeks or 12 sessions were excluded. The MP assessment could have been performed by functional tests (e.g. jump, sprint, stretch-shortening cycle tasks), isometric contractions, and/or isotonic contractions. Twenty-eight studies were included out of 513. Seven studies evaluated MP by stretch-shortening cycle tasks, Ten studies evaluated MP by isometric contractions, and 13 studies assessed MP by isotonic contractions. We were unable to perform a meta-analysis due to the high heterogeneity among the included studies. In an individual study level analysis, we identified that 14 studies found positive effects of chronic stretching on MP. The improvements were observed only in functional tests and isotonic contractions, isometric contractions were not affected by FT. Therefore, FT might have an influence on dynamic MP. However, more studies are necessary to confirm whether FT can positively affect MP. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Restrictive techniques: gastric banding

    Directory of Open Access Journals (Sweden)

    Katia Cristina da Cunha

    2006-03-01

    Full Text Available Surgery for the treatment of severe obesity has a definite role onthe therapeutic armamentarium all over the world. Initiated 40years ago, bariatric surgery has already a long way thanks tohundred of surgeons, who had constantly searched for the besttechnique for the adequate control of severe obesity. Among theimportant breakthroughs in obesity surgery there is theadjustable gastric band. It is a sylastic band, inflatable andadjustable, which is placed on the top of the stomach in order tocreate a 15-20 cc pouch, with an outlet of 1.3cm. The adjustablegastric band has also a subcutaneous reservoir through whichadjustments can be made, according to the patient evolution.The main feature of the adjustable gastric band is the fact thatis minimal invasive, reversible, adjustable and placedlaparoscopically. Then greatly diminishing the surgical traumato the severe obese patient. Belachew and Favretti’s techniqueof laparoscopic application of the adjustable gastric band isdescribed and the evolution of the technique during this years,as we has been practiced since 1998. The perioperative care ofthe patient is also described, as well as the follow-up and shortand long term controls.

  9. Investigating the role of musical genre in human perception of music stretching resistance

    OpenAIRE

    Chen, Jun; Wang, Chaokun

    2017-01-01

    To stretch a music piece to a given length is a common demand in people's daily lives, e.g., in audio-video synchronization and animation production. However, it is not always guaranteed that the stretched music piece is acceptable for general audience since music stretching suffers from people's perceptual artefacts. Over-stretching a music piece will make it uncomfortable for human psychoacoustic hearing. The research on music stretching resistance attempts to estimate the maximum stretchab...

  10. Hypersonic modulation of light in three-dimensional photonic and phononic band-gap materials.

    Science.gov (United States)

    Akimov, A V; Tanaka, Y; Pevtsov, A B; Kaplan, S F; Golubev, V G; Tamura, S; Yakovlev, D R; Bayer, M

    2008-07-18

    The elastic coupling between the a-SiO2 spheres composing opal films brings forth three-dimensional periodic structures which besides a photonic stop band are predicted to also exhibit complete phononic band gaps. The influence of elastic crystal vibrations on the photonic band structure has been studied by injection of coherent hypersonic wave packets generated in a metal transducer by subpicosecond laser pulses. These studies show that light with energies close to the photonic band gap can be efficiently modulated by hypersonic waves.

  11. Vibrational Probes: From Small Molecule Solvatochromism Theory and Experiments to Applications in Complex Systems.

    Science.gov (United States)

    Błasiak, Bartosz; Londergan, Casey H; Webb, Lauren J; Cho, Minhaeng

    2017-04-18

    vibrational Stark effect theory has been considered to be quite appealing and, even in some cases, e.g., carbonyl stretch modes in amide, ester, ketone, and carbonate compounds or proteins, it works quantitatively well, which makes it highly useful in determining the strength of local electric field around the IR chromophore. However, noting that the vibrational frequency shift results from changes of solute-solvent intermolecular interaction potential along its normal coordinate, Pauli exclusion repulsion, polarization, charge transfer, and dispersion interactions, in addition to the electrostatic interaction between distributed charges of both vibrational chromophore and solvent molecules, are to be properly included in the theoretical description of vibrational solvatochromism. Since the electrostatic and nonelectrostatic intermolecular interaction components have distinctively different distance and orientation dependences, they affect the solvatochromic vibrational properties in a completely different manner. Over the past few years, we have developed a systematic approach to simulating vibrational solvatochromic data based on the effective fragment potential approach, one of the most accurate and rigorous theories on intermolecular interactions. We have further elucidated the interplay of local electric field with the general vibrational solvatochromism of small IR probes in either solvents or complicated biological systems, with emphasis on contributions from non-Coulombic intermolecular interactions to vibrational frequency shifts and fluctuations. With its rigorous foundation and close relation to quantitative interpretation of experimental data, this and related theoretical approaches and experiments will be of use in studying and quantifying the structure and dynamics of biomolecules with unprecedented time and spatial resolution when combined with time-resolved vibrational spectroscopy and chemically sensitive vibrational imaging techniques.

  12. 14 CFR 33.33 - Vibration.

    Science.gov (United States)

    2010-01-01

    ... and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure. ...

  13. Melt Stirring by Horizontal Crucible Vibration

    Science.gov (United States)

    Wolf, M. F.; Elwell, D.; Feigelson, R. S.

    1985-01-01

    Horizontal vibration suggested as technique for more effective stirring of melts in crystal-growth apparatus. Vibrational technique may replace accelerated crucible rotation. Potential superiority of vibrational technique shown by preliminary experiments in which ink stirred into water.

  14. Dynamic Contractility and Efficiency Impairments in Stretch-Shortening Cycle Are Stretch-Load-Dependent After Training-Induced Muscle Damage

    NARCIS (Netherlands)

    Vaczi, Mark; Racz, Levente; Hortobagyi, Tibor; Tihanyi, Jozsef

    Vaczi, M, Racz, L, Hortobagyi, T, and Tihanyi, J. Dynamic contractility and efficiency impairments in stretch-shortening cycle are stretch-load-dependent after training-induced muscle damage. J Strength Cond Res 27(8): 2171-2179, 2013To determine the acute task and stretch-load dependency of

  15. Tail modeling in a stretched magnetosphere. I - Methods and transformations

    Science.gov (United States)

    Stern, David P.

    1987-01-01

    A new method is developed for representing the magnetospheric field B as a distorted dipole field. Because Delta-B = 0 must be maintained, such a distortion may be viewed as a transformation of the vector potential A. The simplest form is a one-dimensional 'stretch transformation' along the x axis, concisely represented by the 'stretch function' f(x), which is also a convenient tool for representing features of the substorm cycle. One-dimensional stretch transformations are extended to spherical, cylindrical, and parabolic coordinates and then to arbitrary coordinates. It is shown that distortion transformations can be viewed as mappings of field lines from one pattern to another; the final result only requires knowledge of the field and not of the potentials. General transformations in Cartesian and arbitrary coordinates are derived, and applications to field modeling, field line motion, MHD modeling, and incompressible fluid dynamics are considered.

  16. Alignment of Disks with Lagrangian Stretching in Turbulence

    Science.gov (United States)

    Hunt, Conor; Tierney, Lydia; Kramel, Stefan; Voth, Greg

    2015-11-01

    We study Lagrangian stretching in isotropic turbulence in order to understand both the rotations of disks and the preferential alignment of vorticity with the intermediate strain rate eigenvector. Using velocity gradient tensors from a numerical simulation of homogeneous isotropic turbulence at Rλ = 180, we calculate the Cauchy-Green strain tensors whose eigenvectors provide a natural basis for studying stretching phenomenon. Previous work has shown that rods preferentially align with the vorticity as a result of both quantities independently aligning with the extensional Cauchy-Green eigenvector. In contrast, disks orient with their symmetry axis perpendicular to vorticity and preferentially align with the compressional Cauchy-Green eigenvector. We also find that the intermediate strain rate eigenvector is aligned with the extensional Cauchy-Green eigenvector. A natural consequence is that the intermediate strain rate eigenvector is aligned with the vorticity vector since conservation of angular momentum aligns vorticity with the direction it has been stretched.

  17. Stretching of red blood cells at high strain rates

    Science.gov (United States)

    Mancuso, J. E.; Ristenpart, W. D.

    2017-10-01

    Most work on the mechanical behavior of red blood cells (RBCs) in flow has focused on simple shear flows. Relatively little work has examined RBC deformations in the physiologically important extensional flow that occurs at the entrance to a constriction. In particular, previous work suggests that RBCs rapidly stretch out and then retract upon entering the constriction, but to date no model predicts this behavior for the extremely high strain rates typically experienced there. In this Rapid Communication, we use high speed video to perform systematic measurements of the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We demonstrate that both the Kelvin-Voigt and Skalak viscoelastic models capture the observed stretching dynamics, up to strain rates as high as 2000 s-1. The results indicate that the effective elastic modulus of the RBC membrane at these strain rates is an order of magnitude larger than moduli measured by micropipette aspiration or other low strain rate techniques.

  18. Effects of static stretching on 1-mile uphill run performance.

    Science.gov (United States)

    Lowery, Ryan P; Joy, Jordan M; Brown, Lee E; Oliveira de Souza, Eduardo; Wistocki, David R; Davis, Gregory S; Naimo, Marshall A; Zito, Gina A; Wilson, Jacob M

    2014-01-01

    It is previously demonstrated that static stretching was associated with a decrease in running economy and distance run during a 30-minute time trial in trained runners. Recently, the detrimental effects of static stretching on economy were found to be limited to the first few minutes of an endurance bout. However, economy remains to be studied for its direct effects on performance during shorter endurance events. The aim of this study was to investigate the effects of static stretching on 1-mile uphill run performance, electromyography (EMG), ground contact time (GCT), and flexibility. Ten trained male distance runners aged 24 ± 5 years with an average VO2max of 64.9 ± 6.5 mL·kg-1·min-1 were recruited. Subjects reported to the laboratory on 3 separate days interspersed by 72 hours. On day 1, anthropometrics and V[Combining Dot Above]O2max were determined on a motor-driven treadmill. On days 2 and 3, subjects performed a 5-minute treadmill warm-up and either performed a series of 6 lower-body stretches for three 30-second repetitions or sat still for 10 minutes. Time to complete a 1-mile run under stretching and nonstretching conditions took place in randomized order. For the performance run, subjects were instructed to run as fast as possible at a set incline of 5% until a distance of 1 mile was completed. Flexibility from the sit and reach test, EMG, GCT, and performance, determined by time to complete the 1-mile run, were recorded after each condition. Time to complete the run was significantly less (6:51 ± 0:28 minutes) in the nonstretching condition as compared with the stretching condition (7:04 ± 0:32 minutes). A significant condition-by-time interaction for muscle activation existed, with no change in the nonstretching condition (pre 91.3 ± 11.6 mV to post 92.2 ± 12.9 mV) but increased in the stretching condition (pre 91.0 ± 11.6 mV to post 105.3 ± 12.9 mV). A significant condition-by-time interaction for GCT was also present, with no changes in

  19. Directional Cell Migration in Response to Repeated Substratum Stretching

    Science.gov (United States)

    Okimura, Chika; Iwadate, Yoshiaki

    2017-10-01

    Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Migration properties such as anterior-posterior polarity, directionality, and velocity are regulated not only by the reception of a chemoattractant but also by sensing mechanical inputs from the external environment. In this review, we describe the mechanical response of migrating cells, particularly under repeated stretching of the elastic substratum, highlighting the fact that there appear to be two independent mechanosensing systems that generate the polarity needed for migration. Cells that have no stress fibers, such as Dictyostelium cells and neutrophil-like differentiated HL-60 cells, migrate perpendicular to the stretching direction via myosin II localization. Cells that do possess stress fibers, however, such as fish keratocytes, migrate parallel to the stretching via a stress-fiber-dependent process.

  20. Ultra wide band antennas

    CERN Document Server

    Begaud, Xavier

    2013-01-01

    Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recog