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Artigos de revistas sobre o tema "Spherical top molecule"

Autor: Grafiati

Publicado: 22 de fevereiro de 2025

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1

Rotger, M., V. Boudon, M. Loëte, N. Zvereva-Loëte, L. Margulès, J. Demaison, I. Merke, F. Hegelund e H. Bürger. "The bending triad of the quasi-spherical top molecule SO2F2 in the 550cm−1 region". Journal of Molecular Spectroscopy 238, n.º 2 (agosto de 2006): 145–57. http://dx.doi.org/10.1016/j.jms.2006.04.014.

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2

Inostroza, Natalia, Ricardo Letelier e María Luisa Senent. "On the variational solution of the coupled breathing rotation-vibration of a spherical top molecule". Journal of Mathematical Chemistry 45, n.º 4 (13 de junho de 2008): 1055–59. http://dx.doi.org/10.1007/s10910-008-9392-5.

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3

Chang, Johnny, e Robert E. Wyatt. "Artificial intelligence techniques in the study of multiphoton dynamics: Application to a general vibrating-rotating spherical top molecule". Chemical Physics Letters 121, n.º 4-5 (novembro de 1985): 307–14. http://dx.doi.org/10.1016/0009-2614(85)87184-0.

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4

Paka, I., D. A. Roth, M. Heppa, G. Winnewisser, D. Scouterisc, B. J. Howard e K. M. T. Yamadad. "High resolution spectroscopy of Ar-CH4 and Kr-CH4 in the 7 μ region (j = 1 ← 0 transition)". Zeitschrift für Naturforschung A 53, n.º 8 (1 de agosto de 1998): 725–32. http://dx.doi.org/10.1515/zna-1998-0814.

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Abstract Diode laser spectra of the rare gas - spherical top van der Waals complexes Ar-CH4 and Kr-CH4 were measured in the wavelength region near 1310 cm-1 and assigned. The most prominent lines of both complexes exhibit three dense but well resolved RP0, QR0, and RQ0 branches, correlated to the R(0) transition of the triply degenerate bending vibration v4 of methane, CH4. A model Hamiltonian based on Coriolis coupled states was applied for the assignment, analysis and fitting of the spectra to within the experimental accuracy of ≈ 15 MHz. The rotational B constants of the upper and lower states determined from the three allowed branches appeared to be strongly correlated. The precision in the determination of the rotational B constants of the two complexes was substantially increased by additional recording of several weak transitions in the nearly forbidden QP0 and RR0 branches, which were fitted together with the allowed transitions. The separation between the rare gas atom and the methane molecule in the ground vibrational state was determined to be 3.999 Å and 4.094 Å for Ar-CH4 and Kr-CH4, respectively. The measured small values of the splitting between the K=0 and the K = ±1 levels in the vibrationally excited state (0.39 cm-1 and 0.67 cm-1 for Ar-CH4 and Kr-CH4, respectively), which characterizes the anisotropy of the intermolecular potential, indicated that Kr-CH4 and Ar-CH4 together with Ne-SiH4 represent examples close to the free rotor limit, where the spherical top CH4 is almost free to rotate within the complex. In comparison, the previously analyzed Ar-SiH4 van der Waals molecule is closer to the hindered rotor limit.

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5

Brot, Claude. "Liquides de toupies symétriques: leur tenseur de polarisabilité optique intrinsèque via deux expériences sous champ statique: CH3CN". Canadian Journal of Chemistry 68, n.º 9 (1 de setembro de 1990): 1490–93. http://dx.doi.org/10.1139/v90-228.

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NMR line splitting under a strong static electric field (EF-NMR) allows one to measure the average alignment (second spherical harmonic) of the molecule studied under the influence of the field. This average alignment (per unit squared field) can be formulated theoretically by an expression involving the permanent dipole moment, the anisotropy of the static polarizability, etc. and possibly orientational intercorrelations within the liquid. On the other hand the Kerr constant per molecule can be represented by the same expression, multiplified by a factor that is independent of any static electrical property of the molecule (for a gas this factor would be simply proportional to the anisotropy of the optical polarizability). Consequently the ratio of the above experimental results contains information bearing only on the optical properties. The formalism of the "tensor of polarizability increment" developed by the author for liquids made up of ellipsoidal molecules is employed. It is shown that by combining the above ratio with the constitutive equation for the refractivity of the liquid, the two distinct principal elements of the tensor of polarizability increment of the symmetric top molecules constituting the liquid are immediately obtained. Using then the molecular volume, a van der Waals estimate for the elongation of the molecule, and the index of refraction of the liquid, one can calculate the elements of the optical polarizability tensor invacuo. The method is illustrated by neat acetonitrile for which the necessary experimental data exist in the literature. One finds, in units 1040 C2 m2 J−1 5.06 for the mean polarizability and 2.52 for its anisotropy. A published experimental study using depolarized light scattering in the gas phase indicates that the corresponding figures are 4.96 and 2.49 respectively at λ = 633 nm. Finally and accessorily, it is suggested that dipolar intercorrelations are weak in acetonitrile. Indeed, using an analogous formalism for the static permittivity of the liquid, a value for the permanent moment of the molecule is deduced. This value is within 1% of the experimental gas value. Keywords: polarizability tensors, liquids, Kerr constant, NMR.

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6

Kuyliev, B. T., N. D. Orlova, L. A. Pozdnyakova, L. O. Meyliev, M. A. Rahmonova e Zh N. Huzhamberdieva. "Vibrational-Rotational Interaction in Molecules of the Spherical Top Type". Ukrainian Journal of Physics 59, n.º 3 (março de 2014): 222–25. http://dx.doi.org/10.15407/ujpe59.03.0222.

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7

BUNKER, P. R., e PER JENSEN. "Spherical top molecules and the molecular symmetry group". Molecular Physics 97, n.º 1-2 (20 de julho de 1999): 255–64. http://dx.doi.org/10.1080/00268979909482827.

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8

JENSEN, P. R. BUNKER, PER. "Spherical top molecules and the molecular symmetry group". Molecular Physics 97, n.º 1 (10 de julho de 1999): 255–64. http://dx.doi.org/10.1080/002689799164090.

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9

McDowell, Robin S. "Rotational partition functions for spherical-top molecules". Journal of Quantitative Spectroscopy and Radiative Transfer 38, n.º 5 (novembro de 1987): 337–46. http://dx.doi.org/10.1016/0022-4073(87)90028-8.

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10

Najafi, Mohsen. "Prediction of Thermophysical Properties of Spherical Top Molecules". Russian Journal of Physical Chemistry A 96, n.º 8 (agosto de 2022): 1658–66. http://dx.doi.org/10.1134/s0036024422080167.

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11

Evans, M. W. "Laboratory-frame cross-correlation functions for spherical-top molecules". Physical Review A 35, n.º 7 (1 de abril de 1987): 2989–92. http://dx.doi.org/10.1103/physreva.35.2989.

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12

Krohn, Burton J., e James K. G. Watson. "Perturbations of the dominant approximation in spherical-top molecules". Journal of Molecular Spectroscopy 129, n.º 2 (junho de 1988): 395–435. http://dx.doi.org/10.1016/0022-2852(88)90047-1.

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13

Sadovskii, D. A., e B. I. Zhilinskii. "Qualitative analysis of vibration-rotation hamiltonians for spherical top molecules". Molecular Physics 65, n.º 1 (setembro de 1988): 109–28. http://dx.doi.org/10.1080/00268978800100891.

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14

Millot, G., J. Hetzler, G. Pierre e J. I. Steinfeld. "Infrared double-resonance lineshapes in strongly pumped spherical-top molecules". Spectrochimica Acta Part A: Molecular Spectroscopy 45, n.º 1 (janeiro de 1989): 5–15. http://dx.doi.org/10.1016/0584-8539(89)80021-2.

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15

Ogurtsov, I. Ya, e V. L. Ostrovski. "The quadrupole moments of spherical-top molecules in orbitally degenerate states". Molecular Physics 54, n.º 1 (janeiro de 1985): 119–27. http://dx.doi.org/10.1080/00268978500100091.

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16

Papoušek, Dušan. "Forbidden transitions in molecular vibrational-rotational spectroscopy". Collection of Czechoslovak Chemical Communications 54, n.º 10 (1989): 2555–630. http://dx.doi.org/10.1135/cccc19892555.

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A review is given of the forbidden ( more precisely: perturbation allowed) transistions between molecular vibrational-rotational states including transistions which are induced by the electric dipole and quadrupole moments and the magnetic dipole moment. The basic theory of these transistions is outlined starting with the overall symmetry selection rules, followed by the discussion of the spin statistics isomers, approximate selection rules for the usual vibrational-rotational transistions, and forbidden transistions induced by the electric quadrupole and magnetic dipole moments. Forbidden transistions due to the vibrationally and rotationally induced electric dipole moments are the discussed in detail for symmetric top and spherical top molecules with the emphasis on the physical nature of the various phenomena leading to these transistions. A summary is also given of the most important experimental work on the forbidden transistions in diatomic molecules and polar as well as nonpolar polyatomics.

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17

Pierre, G., D. A. Sadovskii e B. I. Zhilinskii. "Organization of Quantum Bifurcations: Crossover of Rovibrational Bands in Spherical Top Molecules". Europhysics Letters (EPL) 10, n.º 5 (1 de novembro de 1989): 409–14. http://dx.doi.org/10.1209/0295-5075/10/5/004.

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18

Bobin, Bernard, e Jacques Moret-Bailly. "Fourier transform spectroscopy and the vibration-rotation spectra of spherical top molecules". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 51, n.º 7 (julho de 1995): 1231–37. http://dx.doi.org/10.1016/0584-8539(94)00016-5.

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19

Krivtsun, V. M., D. A. Sadovskii e B. I. Zhilinskii. "Critical phenomena and diabolic points in rovibrational energy spectra of spherical top molecules". Journal of Molecular Spectroscopy 139, n.º 1 (janeiro de 1990): 126–46. http://dx.doi.org/10.1016/0022-2852(90)90246-m.

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20

Blokhin, A. P., e M. F. Gelin. "Effect of the intensity of collisions on the orientational relaxation of spherical top molecules". Molecular Physics 87, n.º 2 (10 de fevereiro de 1996): 455–68. http://dx.doi.org/10.1080/00268979600100301.

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21

Braun, P. A., A. M. Shirokov e Yu F. Smirnov. "On the level clustering in the spectra of the non-rigid spherical top molecules". Molecular Physics 56, n.º 3 (20 de outubro de 1985): 573–87. http://dx.doi.org/10.1080/00268978500102531.

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22

Wenger, Ch, V. Boudon, J.-P. Champion e G. Pierre. "Highly-spherical Top Data System (HTDS) software for spectrum simulation of octahedral XY6 molecules". Journal of Quantitative Spectroscopy and Radiative Transfer 66, n.º 1 (julho de 2000): 1–16. http://dx.doi.org/10.1016/s0022-4073(99)00161-2.

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23

Grygiel, Krzysztof. "Anomalous dielectric relaxation in solutions of rigid, dipolar asymmetric-top molecules in spherical solvent". Chemical Physics 532 (abril de 2020): 110702. http://dx.doi.org/10.1016/j.chemphys.2020.110702.

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24

Sarychev, Andrey K., Andrey V. Ivanov, Igor V. Bykov, Konstantin E. Mochalov, Milena S. Shestopalova, V. A. Oleinikov, Kirill A. Prusakov e Dmitry V. Basmanov. "Giant Raman radiation from molecules in a spherical metal shell". Applied photonics 10, n.º 7 (28 de dezembro de 2023): 33–53. http://dx.doi.org/10.15593/2411-4375/2023.7.03.

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The work considers an electrodynamic model of radiation from molecules placed in a metal shell. The model qualitatively describes the enhancement of the surface-enhanced Raman scattering (SERS) signal from spherical nanoparticles coated with a thin silver film. The change in the SERS signal is calculated depending on the thickness of the metal nanolayer on top of the spherical particles. The radiating molecular dipole interacts with the metal shell and excites surface plasmons. Plasmonic oscillations reach a maximum when the frequency of the dipole is close to the plasmon resonance of the metal shell, and the dipole itself is close to the plasmonic shell. It has been theoretically shown that the intensity of secondary radiation generated by spherical nanoparticles coated with a silver film several nanometers thick can reach up to six or more orders of magnitude. The effect of a tenfold amplification of the SERS signal was experimentally demonstrated using the example of a large ensemble of single polystyrene microspheres with an average diameter of about 300 nm, coated with a silver nanolayer, which have characteristic Stokes frequencies of 1001 cm-1, 1602 cm-1. We believe that the tenfold enhancement of Raman scattering is due to the electromagnetic amplification mechanism.

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25

Parson, Robert. "A symmetry‐based model for selective rotational energy transfer in collisions of spherical top molecules". Journal of Chemical Physics 93, n.º 12 (15 de dezembro de 1990): 8731–38. http://dx.doi.org/10.1063/1.459261.

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26

Tarrago, G., e M. Dang Nhu. "Ground state rotational energies of C3v quasi-spherical top molecules: Applications to 16OPF3 and PH3". Journal of Molecular Spectroscopy 111, n.º 2 (junho de 1985): 425–39. http://dx.doi.org/10.1016/0022-2852(85)90017-7.

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27

Park, Youngho, Hanbin Pang e Shoudan Liang. "Continuum Approximations to the Hückel Spectrum of Fullerenes". International Journal of Modern Physics B 11, n.º 13 (30 de maio de 1997): 1607–17. http://dx.doi.org/10.1142/s0217979297000824.

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We discuss several continuum approximations to the tight-binding spectrum of fullerene molecules at the bottom, top and center of the spectrum. The bottom part of the spectrum can be well fit by spherical harmonics, whereas the top part can be understood as due to an electron moving in the magnetic field of a monopole. The center part of the spectrum is described by the theory of González et al. Comparison with the Hückel spectrum of fullerenes, with up to 2160 atoms, yields excellent agreement with the continuum approximations, especially for larger fullerenes.

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28

Kalmykov, Yuri P., Sergey V. Titov e William T. Coffey. "Langevin equation method for the rotational Brownian motion and orientational relaxation in liquids: spherical top molecules". Journal of Molecular Liquids 116, n.º 3 (fevereiro de 2005): 119–23. http://dx.doi.org/10.1016/j.molliq.2004.10.030.

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29

Kim, Jae Gwang, Jae Gyeong Lee e Jeong Jae Wie. "Confinement-Induced Fabrication of Liquid Crystalline Polymeric Fibers". Molecules 27, n.º 17 (1 de setembro de 2022): 5639. http://dx.doi.org/10.3390/molecules27175639.

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In aqueous media, liquid crystalline droplets typically form spherical shapes in order to minimize surface energy. Recently, non-spherical geometry has been reported using molecular self-assembly of surfactant-stabilized liquid crystalline oligomers, resulting in branched and randomly oriented filamentous networks. In this study, we report a polymerization of liquid crystalline polymeric fibers within a micro-mold. When liquid crystal oligomers are polymerized in freely suspended aqueous media, curvilinear and randomly networked filaments are obtained. When reactive liquid crystalline monomers are oligomerized in a micro-channel, however, highly aligned linear fibers are polymerized. Within a top-down microfabricated mold, a bottom-up molecular assembly was successfully achieved in a controlled manner by micro-confinement, suggesting a unique opportunity for the programming architecture of materials via a hybrid approach.

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30

Alexiewicz, W., e K. Grygiel. "Kinetic Theory of the Langevin Saturation in Dilute Solution of Dipolar Symmetric-Top Molecules in Spherical Solvents". Acta Physica Polonica A 114, n.º 4 (outubro de 2008): 667–86. http://dx.doi.org/10.12693/aphyspola.114.667.

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31

Chiu, Ying‐Nan. "Four‐photon selection rules and line strengths in symmetric and spherical‐top molecules and time‐reversal invariance". Journal of Chemical Physics 86, n.º 4 (15 de fevereiro de 1987): 1686–97. http://dx.doi.org/10.1063/1.452167.

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32

Evans, M. W., K. N. Swamy, G. C. Lie e E. Clementi. "Computer Simulation of the Structures and Cross Correlation Functions of Spherical-top Molecules in the Liquid State". Molecular Simulation 1, n.º 3 (março de 1988): 187–206. http://dx.doi.org/10.1080/08927028808080942.

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33

Clodius, William B., e C. Richard Quade. "Internal coordinate formulation for the vibration‐rotation energies of polyatomic molecules. III. Tetrahedral and octahedral spherical top moleculesa)". Journal of Chemical Physics 82, n.º 5 (1 de março de 1985): 2365–79. http://dx.doi.org/10.1063/1.448332.

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34

Jain, A. "Effect of gas temperature on the rotational excitation of spherical top molecules (CH4 and SiH4) by low-energy electrons". Zeitschrift f�r Physik D Atoms, Molecules and Clusters 21, n.º 2 (junho de 1991): 153–61. http://dx.doi.org/10.1007/bf01425594.

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35

Parson, Robert. "Fine‐structure selective collisional energy transfer in spherical top molecules: Evidence for a symmetry‐based mechanism from rovibrational eigenfunctions". Journal of Chemical Physics 95, n.º 12 (15 de dezembro de 1991): 8941–61. http://dx.doi.org/10.1063/1.461226.

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36

Sano, Ken-Ichi, e Kiyotaka Shiba. "In Aqua Manufacturing of a Three-Dimensional Nanostructure Using a Peptide Aptamer". MRS Bulletin 33, n.º 5 (maio de 2008): 524–29. http://dx.doi.org/10.1557/mrs2008.105.

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AbstractTBP-1 is a 12-amino-acid peptide aptamer that has been isolated as a Ti binder using a peptide-phage system. Subsequent analyses have shown that TBP1 also binds Si and Ag, and has the ability to enhance the formation of titania and silica as well as nanoparticles of Ag. TBP-1 is thus a bifunctional peptide: a binder that also acts as a mediator of mineralization. These two functions can be grafted onto heterologous molecules. For instance, mutational analysis of the TBP-1 revealed that its N -terminal hexapeptide, RKLPDA (minTBP-1), is sufficient for Ti binding. When the surface of ferritin, a nano-sized spherical cargo protein, was ornamented with minTBP-1 either genetically or chemically, the resultant modified ferritin acquired the ability to bind Ti and mediate mineralization. By alternately applying the binding and mineralization activities of the minTBP-1-modified nanocage, we were able to construct, in stepwise fashion, multilayer structures composed of titania (or silica) and nanocages. We named this process the biomimetic layer-by-layer (BioLBL) method. By coupling BioLBL with a conventional top-down lithographic method, in aqua structuralization of a three-dimensional (3D) configuration of nanomolecules was realized. As shown in this article, binding and mineralization activities of peptide aptamers, when they are combined with nanostructured materials, play active roles in manufacturing nanostrucutre in aqua.

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37

Losic, Dusan, Ken Short, Justin Gooding e Joe Shapter. "Scanning probe microscopy characterization of immobilized enzyme molecules on a biosensor surface: Visualisation of individual molecules". Journal of the Serbian Chemical Society 69, n.º 2 (2004): 93–106. http://dx.doi.org/10.2298/jsc0402093l.

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Scanning probe microscopy techniques were used to study immobilized enzyme molecules of glucose oxidase (GOD) on a biosensor surface. The study was carried out in order to optimize atomic force microscopy (AFM) imaging and reveal themolecular resolution of individual GOD molecules. Chemically modified AFM tips and the light tapping mode were found to be the optimal conditions for imaging soft biomolecules such as GOD. The information obtained from the AFM images included spatial distribution and organization of the enzyme molecules on the surface, surface coverage and shape, size and orientation of individual molecules. Two typical shapes of GOD molecules were found, spherical and butterfly, which are in accordance with the shapes obtained from scanning tunnelling microscopy (STM) images. Using a model of the orientation of the GOD molecules on the surface, these shapes are assigned to the enzyme standing and lying on the surface. After AFM tip deconvolution, the size of the spherical shaped GOD molecules was found to be 12 ?2.1 nm in diameter, whereas the butterfly shapes were 16.5 ? 3.3 nm x10.2 ? 2.5 nm. Corresponding STM images showed smaller lateral dimensions of 10 _1nm_ 6 ?1nm and 6.5 ? 1 nm x5 ? 1 nm. The disagreement between these two techniques is attributed to the deformation of the GOD molecules caused by the tapping process.

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38

Fan, Kang Qi, Chun Hui Xu e Feng Bo Chao. "A Model of Adhesive Contact between a Spherical Tip and a Flat Surface". Advanced Materials Research 860-863 (dezembro de 2013): 2700–2706. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.2700.

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There have been increasing research interests in the measurement of the mechanical properties of nanoscale materials by pressing a spherical tip into surfaces of the tested materials. To acquire a better understanding of this process, a model of adhesive contact between a spherical tip and a flat surface is developed by employing the Hamaker hypotheses and molecular dynamics (MD) method. With this model, the deformation characteristics of the tested surface are illustrated by the key snapshots of the deformed surface and the corresponding curves of pressure distribution. The results indicate that the contact can be formed before the tip impresses into the surface. Moreover, the variation of the adhesive force with the distance is recorded during the approach and separation processes, and the adhesion hysteresis is demonstrated by the force-distance curve. Additionally, the stepwise increase of the contact radius with a decrease in the distance is revealed and investigated.

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39

Molet, Pau, Luz Karimé Gil-Herrera, Juan Luis Garcia-Pomar, Niccolò Caselli, Álvaro Blanco, Cefe López e Agustín Mihi. "Large area metasurfaces made with spherical silicon resonators". Nanophotonics 9, n.º 4 (11 de março de 2020): 943–51. http://dx.doi.org/10.1515/nanoph-2020-0035.

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AbstractHigh-index dielectric nanostructures have emerged as an appealing complement to plasmonic nanostructures, offering similar light management capabilities at the nanoscale but free from the inherent optical losses. Despite the great interest in these all-dielectric architectures, their fabrication still requires cumbersome fabrication techniques that limit their implementation in many applications. Hence, the great interest in alternative scalable procedures. Among those, the fabrication of silicon spheres is at the forefront, with several routes available in the literature. However, the exploitation of the Mie modes sustained by these silicon resonators is limited over large areas by polydispersity or a lack of long-range order. Here, we present an all-dielectric metamaterial fabricated with a low cost and highly scalable technique: a combination of soft imprinting nanolithography and chemical vapor deposition. The resulting all-dielectric metasurface is composed of an array of silicon hemispheres on top of a high refractive index dielectric substrate. This architecture allows the exploitation of high-quality Mie resonances at a large scale due to the high monodispersity of the hemispheres organized in a single crystal two-dimensional lattice. The optical response of the metasurface can be engineered by the design parameters of the nanoimprinted structure. We further demonstrate the potential of this platform to enhance light emission by coupling dye molecules to the sustained Mie resonances and measuring both an eight-fold amplified signal and a triple lifetime reduction.

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40

Ritze, H. H. "The Role of “Rotational Freezing” in the Polarisation-Dependent Two-Photon Excitation of Triply Degenerate Vibrations in Spherical-Top-Molecules". Annalen der Physik 498, n.º 6-8 (1986): 545–72. http://dx.doi.org/10.1002/andp.19864980616.

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41

Latter, William B., e Joseph L. Hora. "Investigating the near-IR properties of PN: Deep imaging of molecular hydrogen emission". Symposium - International Astronomical Union 180 (1997): 254. http://dx.doi.org/10.1017/s0074180900130724.

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We present the first results of a deep near-infrared narrowband imaging study of several planetary nebulae. The data were acquired using the University of Hawaii 2.2m telescope on Mauna Kea and the “QUIRC” 1024 × 1024 array camera. With these sensitive high spatial resolution imaging data, we are able to explore in detail where H2 is found relative to the ionized region in planetary nebulae at various stages of evolution (See Figure 1, for an example). The objects were selected from previous studies to have evidence for extended emission from H2, and they are at several differing phases of central star evolution. The presence of molecules in the UV–flooded environment of a planetary nebula cannot be explained without highly non-spherical geometries and high densities, or clumping. Although there can be an ambiguity in the excitation mechanism (UV photons or shocks), the location of H2 emission identifies regions of the nebula with sufficient dust shielding and density for the survival of molecular species. The emission morphology also provides information that helps identify which excitation mechanism is most likely. When combined with data provided by other molecular studies, we can examine how the photodissociation region evolves through the circumstellar envelope as the planetary nebula tracks across the top of the HR diagram. We can also consider how morphological evolution of the nebula, through interacting winds and shocks, might provide the conditions necessary for molecular survival.

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42

Masir, Amin Nouroozi, Abolfazl Darvizeh e Asghar Zajkani. "Nanoindentation on the bio-inspired high-performance nature composite by molecular dynamics method". Advanced Composites Letters 28 (1 de janeiro de 2019): 096369351986016. http://dx.doi.org/10.1177/0963693519860162.

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The determination of mechanical properties at the nanoscale is of such importance today that researchers pay special attention to it. Discovering the mechanical properties of biological composite structures in the nanoscale is much interesting today. Top neck mollusk shells are among biomaterial nanocomposites that their layered structures are composed of organic and inorganic materials. Since the nanoindentation process is known as an efficient method to determine mechanical properties like elastic modulus and hardness in small scale, therefore, due to some limitations of considering all peripheral parameters, particular simulations of temperature effect in the atomic scale are considerable. The present article provides a molecular dynamics approach for modeling the nanoindentation mechanism with three types of pyramidal, cubic, and spherical indenters at different temperatures of 173, 273, 300, and 373°K. Based on load-indentation depth diagrams and Oliver–Pharr equations, research findings indicate that the temperature has weakened the power between the biological atoms; this leads to reduced mechanical properties. An increase in temperature causes a reduction in elastic modulus and hardness. There was correspondence between the results obtained from the spherical indenter and experimental data. This study can be regarded as a novel benchmark study for further research studies which tend to consider structural responses of the various bio-inspired nanocomposites.

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Alexiewicz, W., e K. Grygiel. "Cole-Cole Plots for Linear and Nonlinear Dielectric Relaxation in Solutions of Rigid Highly Dipolar Symmetric-Top Molecules in Spherical Solvents". Acta Physica Polonica A 114, n.º 4 (outubro de 2008): 687–98. http://dx.doi.org/10.12693/aphyspola.114.687.

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Sarka, Kamil, Jean Demaison, Laurent Margulès, Ilona Merke, Nils Heineking, Hans Bürger e Helmut Ruland. "Centrifugal Distortion Analysis of a Near-Spherical Top, SO2F2: The First Determination of All Six Quartic Centrifugal Distortion Constants for an Asymmetric Top". Journal of Molecular Spectroscopy 200, n.º 1 (março de 2000): 55–64. http://dx.doi.org/10.1006/jmsp.1999.8018.

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XIAO, WENDE, ZHIJUN YAN, SUNIL SINGH KUSHVAHA, MAOJIE XU e XUE-SEN WANG. "DIFFERENT GROWTH BEHAVIOR OF Ge, Al AND Sb ON GRAPHITE". Surface Review and Letters 13, n.º 02n03 (abril de 2006): 287–96. http://dx.doi.org/10.1142/s0218625x06008025.

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Growth of Ge , Al and Sb on highly oriented pyrolytic graphite (HOPG) was systematically investigated using in situ scanning tunneling microscopy (STM). At room temperature (RT), three dimensional (3D) clusters of all three elements nucleate and grow at the step edges and defect sites of HOPG. The clusters of Al and Ge form chains, while Sb islands are mostly isolated. With further deposition at RT, Al clusters grow and coarsen into faceted islands with craters on the top (111) facets, whereas ramified single- and double-layer cluster islands are observed for Ge . When deposited or annealed at T ≥ 175° C , Ge forms crystallites but with randomly oriented facets. As spherical Sb islands grow beyond certain size, (111) facets appear on the top. Additionally, crystalline 2D films and 1D nanorods are observed for Sb deposited at RT. At T ≈ 100° C and higher flux, only the 2D and 1D Sb islands are formed. These different growth behaviors reflect the unique nature in which the atoms (molecules), clusters and crystallites of each element interact with HOPG surface and with each other.

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Parson, Robert. "Erratum: A symmetry‐based model for selective rotational energy transfer in collisions of spherical top molecules [J. Chem. Phys. 93, 8731 (1990)]". Journal of Chemical Physics 95, n.º 7 (outubro de 1991): 5492. http://dx.doi.org/10.1063/1.461840.

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Holmes, Thomas R., e Amy S. Paller. "Gene Regulation Using Spherical Nucleic Acids to Treat Skin Disorders". Pharmaceuticals 13, n.º 11 (2 de novembro de 2020): 360. http://dx.doi.org/10.3390/ph13110360.

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Spherical nucleic acids (SNAs) are nanostructures consisting of nucleic acids in a spherical configuration, often around a nanoparticle core. SNAs are advantageous as gene-regulating agents compared to conventional gene therapy owing to their low toxicity, enhanced stability, uptake by virtually any cell, and ability to penetrate the epidermal barrier. In this review we: (i) describe the production, structure and properties of SNAs; (ii) detail the mechanism of SNA uptake in keratinocytes, regulated by scavenger receptors; and (iii) report how SNAs have been topically applied and intralesionally injected for skin disorders. Specialized SNAs called nanoflares can be topically applied for gene-based diagnosis (scar vs. normal tissue). Topical SNAs directed against TNFα and interleukin-17A receptor reversed psoriasis-like disease in mouse models and have been tested in Phase 1 human trials. Furthermore, SNAs targeting ganglioside GM3 synthase accelerate wound healing in diabetic mouse models. Most recently, SNAs targeting toll-like receptor 9 are being used in Phase 2 human trials via intratumoral injection to induce immune responses in Merkel cell and cutaneous squamous cell carcinoma. Overall, SNAs are a valuable tool in bench-top and clinical research, and their advantageous properties, including penetration into the epidermis after topical delivery, provide new opportunities for targeted therapies.

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Busont, Océane, Gaëlle Durambur, Sophie Bernard, Carole Plasson, Camille Joudiou, Laura Baude, Françoise Chefdor et al. "Black Poplar (Populus nigra L.) Root Extracellular Trap, Structural and Molecular Remodeling in Response to Osmotic Stress". Cells 12, n.º 6 (9 de março de 2023): 858. http://dx.doi.org/10.3390/cells12060858.

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The root extracellular trap (RET) consists of root-associated, cap-derived cells (root AC-DCs) and their mucilaginous secretions, and forms a structure around the root tip that protects against biotic and abiotic stresses. However, there is little information concerning the changes undergone by the RET during droughts, especially for tree species. Morphological and immunocytochemical approaches were used to study the RET of black poplar (Populus nigra L.) seedlings grown in vitro under optimal conditions (on agar-gelled medium) or when polyethylene glycol-mediated (PEG6000—infused agar-gelled medium) was used to mimic drought conditions through osmotic stress. Under optimal conditions, the root cap released three populations of individual AC-DC morphotypes, with a very low proportion of spherical morphotypes, and equivalent proportions of intermediate and elongated morphotypes. Immunolabeling experiments using anti-glycan antibodies specific to cell wall polysaccharide and arabinogalactan protein (AGP) epitopes revealed the presence of homogalacturonan (HG), galactan chains of rhamnogalacturonan-I (RG-I), and AGPs in root AC-DC cell walls. The data also showed the presence of xylogalacturonan (XGA), xylan, AGPs, and low levels of arabinans in the mucilage. The findings also showed that under osmotic stress conditions, both the number of AC-DCs (spherical and intermediate morphotypes) and the total quantity of mucilage per root tip increased, whereas the mucilage was devoid of the epitopes associated with the polysaccharides RG-I, XGA, xylan, and AGPs. Osmotic stress also led to reduced root growth and increased root expression of the P5CS2 gene, which is involved in proline biosynthesis and cellular osmolarity maintenance (or preservation) in aerial parts. Together, our findings show that the RET is a dynamic structure that undergoes pronounced structural and molecular remodeling, which might contribute to the survival of the root tip under osmotic conditions.

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Dupont, V., e F. Sansoz. "Molecular dynamics study of crystal plasticity during nanoindentation in Ni nanowires". Journal of Materials Research 24, n.º 3 (março de 2009): 948–56. http://dx.doi.org/10.1557/jmr.2009.0103.

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Molecular dynamics simulations were performed to gain fundamental insight into crystal plasticity, and its size effects in nanowires deformed by spherical indentation. This work focused on <111>-oriented single-crystal, defect-free Ni nanowires of cylindrical shape with diameters of 12 and 30 nm. The indentation of thin films was also comparatively studied to characterize the influence of free surfaces in the emission and absorption of lattice dislocations in single-crystal Ni. All of the simulations were conducted at 300 K by using a virtual spherical indenter of 18 nm in diameter with a displacement rate of 1 m·s−1. No significant effect of sample size was observed on the elastic response and mean contact pressure at yield point in both thin films and nanowires. In the plastic regime, a constant hardness of 21 GPa was found in thin films for penetration depths larger than 0.8 nm, irrespective of variations in film thickness. The major finding of this work is that the hardness of the nanowires decreases as the sample diameter decreases, causing important softening effects in the smaller nanowire during indentation. The interactions of prismatic loops and dislocations, which are emitted beneath the contact tip, with free boundaries are shown to be the main factor for the size dependence of hardness in single-crystal Ni nanowires during indentation.

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Nishi, Noriaki, Takahisa Jitsuno, Koji Tsubakimoto, Shinichi Matsuoka, Noriaki Miyanaga e Masahiro Nakatsuka. "Two-Dimensional Multi-Lens Array with Circular Aperture Spherical Lens for Flat-Top Irradiation of Inertial Confinement Fusion Target". Optical Review 7, n.º 3 (maio de 2000): 216–20. http://dx.doi.org/10.1007/s10043-000-0216-5.

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