A relook at Reissner's theory of plates in bending

Shear deformation and higher order theories of plates in bending are (generally) based on plate element equilibrium equations derived either through variational principles or other methods. They involve coupling of flexure with torsion (torsion-type) problem and if applied vertical load is along one face of the plate, coupling even with extension problem. These coupled problems with reference to vertical deflection of plate in flexure result in artificial deflection due to torsion and increased deflection of faces of the plate due to extension. Coupling in the former case is eliminated earlier using an iterative method for analysis of thick plates in bending. The method is extended here for the analysis of associated stretching problem in flexure.

Griffiths phase-like behavior and spin-phonon coupling in double perovskite Tb(2)NiMnO(6)

The Griffiths phase-like features and the spin-phonon coupling effects observed in Tb(2)NiMnO(6) are reported. The double perovskite compound crystallizes in monoclinic P2(1)/n space group and exhibits a magnetic phase transition at T(c) similar to 111 K as an abrupt change in magnetization. A negative deviation from ideal Curie-Weiss law exhibited by 1/chi(T) curves and less-than-unity susceptibility exponents from the power-law analysis of inverse susceptibility are reminiscent of Griffiths phase-like features. Arrott plots derived from magnetization isotherms support the inhomogeneous nature of magnetism in this material. The observed effects originate from antiferromagnetic interactions that arise from inherent disorder in the system. Raman scattering experiments display no magnetic-order-induced phonon renormalization below Tc in Tb(2)NiMnO(6), which is different from the results observed in other double perovskites and is correlated to the smaller size of the rare earth. The temperature evolution of full-width-at-half-maximum for the stretching mode at 645 cm(-1) presents an anomaly that coincides with the magnetic transition temperature and signals a close connection between magnetism and lattice in this material. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671674]

Fourier transform infrared microspectroscopy identifies protein propionylation in histone deacetylase inhibitor treated glioma cells

Histone deacetylase inhibitors (HDIs) have attracted considerable attention as potential drug molecules in tumour biology. In order to optimise chemotherapy, it is important to understand the mechanisms of regulation of histone deacetylase (HDAC) enzymes and modifications brought by various HDIs. In the present study, we have employed Fourier transform infrared microspectroscopy (FT-IRMS) to evaluate modifications in cellular macromolecules subsequent to treatment with various HDIs. In addition to CH3 (methyl) stretching bands at 2872 and 2960 cm1, which arises due to acetylation, we also found major changes in bands at 2851 and 2922 cm1, which originates from stretching vibrations of CH2 (methylene) groups, in valproic acid treated cells. We further demonstrate that the changes in CH2 stretching are concentration-dependent and also induced by several other HDIs. Recently, HDIs have been shown to induce propionylation besides acetylation [1]. Since propionylation involves CH2 groups, we hypothesized that CH2 vibrational frequency changes seen in HDI treated cells could arise due to propionylation. As verification, pre-treatment of cells with propionyl CoA synthetase inhibitor resulted in loss of CH2 vibrational changes in histones, purified from valproic acid treated cells. This was further proved by western blot using propionyl-lysine specific antibody. Thus we demonstrate for the first time that propionylation could be monitored by studying CH2 stretching using IR spectroscopy and further provide a platform for monitoring HDI induced multiple changes in cells. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Spin-Electron-Phonon Excitation in Re-based Half-Metallic Double Perovskites

A remarkable hardening (similar to 30 cm(-1)) of the normal mode of vibration associated with the symmetric stretching of the oxygen octahedra for the Ba2FeReO6 and Sr2CrReO6 double perovskites is observed below the corresponding magnetic ordering temperatures. The very large magnitude of this effect and its absence for the antisymmetric stretching mode provide evidence against a conventional spin-phonon coupling mechanism. Our observations are consistent with a collective excitation formed by the combination of the vibrational mode with oscillations of Fe or Cr 3d and Re 5d occupations and spin magnitudes.

Theoretical analysis of photoinduced H-atom elimination in thiophenol

The photoinduced hydrogen elimination reaction in thiophenol via the conical intersections of the dissociative (1)pi sigma* excited state with the bound (1)pi pi* excited state and the electronic ground state has been investigated with ab initio electronic-structure calculations and time-dependent quantum wave-packet calculations. A screening of the coupling constants of the symmetry-allowed coupling modes at the (1)pi pi*-(1)pi sigma* and (1)pi sigma*-S-0 conical intersection shows that the SH torsional mode is by far the most important coupling mode at both conical intersections. A model including three intersecting potential-energy surfaces (S-0, (1)pi pi*, (1)pi sigma*) and two nuclear degrees of freedom (SH stretch and SH torsion) has been constructed on the basis of ab initio complete-active-space self-consistent field and multireference second-order perturbation theory calculations. The nonadiabatic quantum wave-packet dynamics initiated by optical excitation of the (1)pi pi* and (1)pi sigma* states has been explored for this three-state two-coordinate model. The photodissociation dynamics is characterized in terms of snapshots of time-dependent wave packets, time-dependent electronic population probabilities, and the branching ratio of the (2)sigma/(2)pi electronic states of the thiophenoxyl radical. The dependence of the timescale of the photodissociation process and the branching ratio on the initial excitation of the SH stretching and SH torsional vibrations has been analyzed. It is shown that the node structure, which is imposed on the nuclear wave packets by the initial vibrational preparation as well as by the transitions through the conical intersections, has a profound effect on the photodissociation dynamics. The effect of additional weak coupling modes of CC twist (nu(16a)) and ring-distortion (nu(16b)) character has been investigated with three-dimensional and four-dimensional time-dependent wave-packet calculations, and has been found to be minor. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.4709608]

Deformation field in indentation of a granular ensemble

An experimental study has been made of the flow field in indentation of a model granular material. A granular ensemble composed of spherical sand particles with average size of 0.4 mm is indented with a flat ended punch under plane-strain conditions. The region around the indenter is imaged in situ using a high-speed charge-coupled device (CCD) imaging system. By applying a hybrid image analysis technique to image sequences of the indentation, flow parameters such as velocity, velocity gradient, and strain rate are measured at high resolution. The measurements have enabled characterization of the main features of the flow such as dead material zones, velocity jumps, localization of deformation, and regions of highly rotational flow resembling vortices. Implications for validation of theoretical analyses and applications are discussed.

Infrared Spectra of Dimethylphenanthrenes in the Gas phase

Infrared spectra of atmospherically and astronomically important dimethylphenanthrenes (DMPs), namely 1,9-DMP, 2,4-DMP, and 3,9-DMP, were recorded in the gas phase from 400 to 4000 cm(-1) with a resolution of 0.5 cm(-1) at 110 degrees C using a 7.2 m gas cell. DFT calculations at the B3LYP/6-311G** level were carried out to get the harmonic and anharmonic frequencies and their corresponding intensities for the assignment of the observed bands. However, spectral assignments could not be made unambiguously using anharmonic or selectively scaled harmonic frequencies. Therefore, the scaled quantum mechanical (SQM) force field analysis method was adopted to achieve more accurate assignments. In this method force fields instead of frequencies were scaled. The Cartesian force field matrix obtained from the Gaussian calculations was converted to a nonredundant local coordinate force field matrix and then the force fields were scaled to match experimental frequencies in a consistent manner using a modified version of the UMAT program of the QCPE package. Potential energy distributions (PEDs) of the normal modes in terms of nonredundant local coordinates obtained from these calculations helped us derive the nature of the vibration at each frequency. The intensity of observed bands in the experimental spectra was calculated using estimated vapor pressures of the DMPs. An error analysis of the mean deviation between experimental and calculated intensities reveal that the observed methyl C-H stretching intensity deviates more compared to the aromatic C-H and non C-H stretching bands.

Mechanical properties of ZnS nanowires and thin films: Microscopic origin of the dependence on size and growth direction

Mechanical properties of ZnS nanowires and thin films are studied as a function of size and growth direction using all-atom molecular dynamics simulations. Using the stress-strain relationship we extract Young's moduli of nanowires and thin films at room temperature. Our results show that Young's modulus of 0001] nanowires has strong size dependence. On the other hand, 01 (1) over bar0] nanowires do not exhibit a strong size dependence of Young's modulus in the size range we have investigated. We provide a microscopic understanding of this behavior on the basis of bond stretching and contraction due to the rearrangement of atoms in the surface layers. The ultimate tensile strengths of the nanowires do not show much size dependence. To investigate the mechanical behavior of ZnS in two dimensions, we calculate Young's modulus of thin films under tensile strain along the 0001] direction. Young's modulus of thin films converges to the bulk value more rapidly than that of the 0001] nanowire.

Vanadium pentoxide nanobelts: One pot synthesis and its lithium storage behavior

In this paper, we report a synthesis, characterization and electrochemical properties of V2O5 nanobelts. V2O5 nanobelts have been prepared via hydrothermal treatment of commercial V2O5 in acidic (HCl/H2SO4) medium at relatively low temperature (160 degrees C). The hydrothermally derived products have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photo electron spectroscopy (XPS), UV-Vis spectroscopy, Scanning/Transmission electron microscopy (SEM/TEM). XRD pattern of V2O5 nanobelts show an orthorhombic phase. From the FTIR spectrum, the peak observed at 1018 cm-1 is characteristic of the stretching vibration mode of the terminal vanadyl, V = O. The UV-Vis absorption spectrum of V2O5 nanobelts show maximum absorbance at 430 nm, which was blue-shifted compared to that of bulk V2O5. TEM micrographs reveal that the products consist of nanobelts of 40-200 nm in thickness and several tens of micrometers in length. The electrochemical analysis shows an initial discharge capacity of 360 mAh g-1 and its almost stabilized capacity is reached to 250 mAh g-1 after 55 cycles. A probable reaction mechanism for the formation of orthorhombic V2O5 nanobelts is proposed.

Optical, electrochemical and morphological investigations of poly (3,4-propylenedioxythiophene)-sultone (PProDOT-S) thin films

In this paper, we have carried out thin film characterization of poly(3,4-propylenedioxythiophene)-sultone (PProDOT-S), a derivative of electrochromic poly(3,4-propylenedioxythiophene) (PProDOT). PProDOT-S was deposited onto transparent conducting oxide coated glass substrates by solution casting method. Single wavelength spectrophotometry is used to monitor the switching speed and contrast ratio at maximum wavelength (lambda (max)). The percentage transmittance at the lambda (max) of the neutral polymer is monitored as a function of time when the polymer film is repeatedly switched. This experiment gives a quantitative measure of the speed with which a film is able to switch between the two states i.e. the coloured and the bleached states. PProDOT-S films were switched at a voltage of 1 center dot 9 V with a switching speed of 2 s at lambda (max) of 565 nm and showed a contrast of similar to 37%. Cyclic voltammetry performed at different scan rates have shown the characteristic anodic and cathodic peaks. The structural investigations of PProDOT-S films by IR spectra were in good agreement with previously reported results. Raman spectra of PProDOT-S showed a strong Raman peak at 1509 cm (-aEuro parts per thousand 1) and a weak peak at 1410 cm (-aEuro parts per thousand 1) due to the C = C asymmetric and symmetric stretching vibrations of thiophene rings. The morphological investigations carried out by using scanning electron microscope (SEM) of polymer films have shown that these polymers are found to be arranged in dense packed clusters with non-uniform distribution having an average width and length of 95 nm and 160 nm, respectively.

Na0.33V2O5 center dot 1.5H(2)O nanorings/nanorods and Na0.33V2O5 center dot 1.5H(2)O/RGO composite fabricated by a facile one pot synthesis and its lithium storage behavior

In this work, Na0.33V2O5 center dot 1.5H(2)O nanorings/nanorods and Na0.33V2O5 center dot 1.5H(2)O/reduced graphene oxide (RGO) composites have been prepared through a facile hydrothermal route in acidic medium at 200 degrees C for 2 days. The hydrothermally derived products have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-Visible spectroscopy, Thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and electrochemical discharge-charge cycling in lithium ion battery. XRD pattern exhibits the layered structure of Na0.33V2O5 center dot 1.5H(2)O and the composite shows the presence of RGO at 2 theta = 25.8 degrees. FTIR spectrum shows that the band at 760 cm(-1) could be assigned to a V-OH2 stretching mode due to coordinated water. Raman spectrum shows that the band at 264 cm(-1) is due to the presence of water molecules between the layers. FESEM/TEM micrographs reveal that the products consist of nanorings of inner diameter 5 mu m and thickness of the ring is found to be 200-300 nm. Addition of exfoliated graphene oxide (EGO) destroys the formation of rings. The reduction of EGO sheets into RGO is also evidenced by the red shift of the absorbance peak from 228 nm to 264 nm. In this composite Na0.33V2O5 center dot 1.5H(2)O nanorods may adhere to the surface of RGO and/or embedded in the RGO nanosheets. As a result, an effective three-dimensional conducting network was formed by bridging RGO nanosheets, which can facilitate electron transport effectively and thus improve the kinetics and rate performance of Na0.33V2O5 center dot 1.5H(2)O nanorings/nanorods. The Na0.33V2O5 center dot 1.5H(2)O/RGO composites exhibited a discharge capacity of 340 mAh g(-1) at a current density of 0.1 mA g(-1) and also an improved cyclic stability. RGO plays a `flexible confinement' function to enwrap Na0.33V2O5 center dot 1.5H(2)O nanorods, which can compensate for the volume change and prevent the detachment and agglomeration of pulverized Na0.33V2O5 center dot 1.5H(2)O, thus extending the cycling life of the electrode. A probable reaction mechanism for the formation of Na0.33V2O5 center dot 1.5H(2)O nanorings is also discussed. (C) 2012 Elsevier B.V. All rights reserved.

Two-Dimensional Correlation Analysis of Temperature-Dependent FT-IR Spectra of Oleic Acid

In the present study, variable temperature FT-IR spectroscopic investigations were used to characterize the spectral changes in oleic acid during heating oleic acid in the temperature range from -30 degrees;C to 22 degrees C. In order to extract more information about the spectral variations taking place during the phase transition process, 2D correlation spectroscopy (2DCOS) was employed for the stretching (C?O) and rocking (CH2) band of oleic acid. However, the interpretation of these spectral variations in the FT-IR spectra is not straightforward, because the absorption bands are heavily overlapped and change due to two processes: recrystallization of the ?-phase and melting of the oleic acid. Furthermore, the solid phase transition from the ?- to the a-phase was also observed between -4 degrees C and -2 degrees C. Thus, for a more detailed 2DCOS analysis, we have split up the spectral data set in the subsets recorded between -30 degrees C to -16 degrees C, -16 degrees C to 10 degrees C, and 10 degrees C to 22 degrees C. In the corresponding synchronous and asynchronous 2D correlation plots, absorption bands that are characteristic of the crystalline and amorphous regions of oleic acid were separated.

A method of designing seamless connectivity algorithm in ubiquitous networks

The b-phase of polyvinylidene fluoride (PVDF) is well known for its piezoelectric properties. PVDF films have been developed using solvent cast method. The films thus produced are in a-phase. The a-phase is transformed to piezoelectric b-phase when the film is hotstretched with various different stretching factors at various different temperatures. The films are then characterized in terms of their mechanical properties and surface morphological changes during the transformation from a- to b-phases by using X-ray diffraction, differential scanning calorimeter, Raman spectra, Infrared spectra, tensile testing, and scanning electron microscopy. The films showed increased crystallinity with stretching at temperature up to 808C. The optimum conditions to achieve b-phase have been discussed in detail. The fabricated PVDF sensors have been tested for free vibration and impact on plate structure, and its response is compared with conventional piezoelectric wafer type sensor. The resonant and antiresonant peaks in the frequency response of PVDF sensor match well with that of lead zirconate titanate wafer sensors. Effective piezoelectric properties and the variations in the frequency response spectra due to free vibration and impact loading conditions are reported. POLYM. ENG. SCI., 00:000–000, 2012. ª2012 Society of Plastics Engineers

Criteria for thermally induced atomization and catastrophic breakup of acoustically levitated droplet

We report thermally induced instability leading to catastrophic breakup in acoustically levitated vaporizing fuel droplets. Change in surface tension and viscosity with increase in droplet temperature causes wide fluctuations in droplet aspect ratio. If the viscous damping of aspect ratio oscillation is not strong enough, the droplet goes through unbounded stretching. If the droplet exceeds a critical Weber number locally, a bag type and capillary wave induced atomization can occur, which leads to catastrophic breakup. A stability criterion has been established based on the inhomogeneity of Bernoulli (acoustic) pressure and surface tension of the droplet in terms of a local Weber number and Ohnesorge number. This instability is thermally induced in a droplet which does not experience instabilities without heating. (C) 2012 Elsevier Ltd. All rights reserved.

Photophysical behavior of poly(propyl ether imine) dendrimer in the presence of nitroaromatic compounds

This paper deals with a study of the photophysical property of poly(ether imine) (PETIM) dendritic macromolecule in the presence of aromatic compounds. The inherent photoluminescence property of the dendrimer undergoes quenching in the presence of guest aromatic nitro-compounds. From life-time measurements study, it is inferred that the lifetimes of luminescent species of the dendrimer are not affected with nitrophenols as guest molecules, whereas nitrobenzenes show a marginal change in the lifetimes of the species. Raman spectral characteristic of the macromolecular host-guest complex is conducted in order to identify conformational change of the dendrimer and a significant change in the stretching frequencies of methylene moieties of the dendrimer is observed for the complex with 1,3,5-trinitrobenzene, when compared to other complexes, free host and guest molecules. The photophysical behavior of electron-rich, aliphatic, neutral dendritic macromolecule in the presence of electron-deficient aromatic molecules is illustrated in the present study. (C) 2012 Elsevier B.V. All rights reserved.