An Inertial Reference Frame Method for the Simulation of the Effect of Longitudinal Force to the Dynamics of Railway Wheelsets

In the current practice of wagon dynamics simulation, traction and braking forces are seldom considered although such forces modify the wheel-rail contact parameters and hence the wheelset dynamics. On the other hand, whilst the traction and braking forces are considered in the simulation of train and locomotive systems, their lateral dynamics is predominantly disregarded. Therefore, there exists a gap in the knowledge of the effect of the application of the longitudinal forces to the lateral dynamics of wagons; this paper aims at bridging this gap. An inertia reference frame method available in the literature has been extended for the purpose. This paper reports the formulation and presents numerical examples of a single wheelset contained within a bogie frame subjected to longitudinal forces of varying severity. The results have been validated where possible.     

Large dynamic Stokes shift of DNA intercalation dye Thiazole Orange has contribution from a high-frequency mode

Fluorescence of the cyanine dye Thiazole Orange (TO) is quenched by intramolecular twisting in the excited state. In polypeptide nucleic acids, a vibrational progression in a 1400 cm(-1) mode depends on base pairing, from which follows that the high-frequency displacement is coupled to the twist coordinate. The coupling is intrinsic to TO. This is shown by femtosecond fluorescence upconversion and transient absorption spectroscopy with the dye in methanol solution. Narrow emission from the Franck-Condon state shifts to the red and broadens within 100 fs. The radiative rate does not decrease during this process. Vibrational structure builds up on a 200 fs time scale; it is assigned to asymmetric stretching activity in the methine bridge. Further Stokes shift and decay are observed over 2 ps. Emission from the global S(1) minimum is discovered in an extremely wide band around 12 000 cm(-1). As the structure twists away from the Franck-Condon region, the mode becomes more displaced and overlap with increasingly higher vibrational wave functions of the electronic ground state is achieved. Twisting motion is thus leveraged into a fast-shrinking effective energy gap between the two electronic states, and internal conversion ensues.     

Experimental Investigation of Wheel/Rail Rolling Contact at Railhead Edge

Wheel-rail rolling contact at railhead edge, such as a gap in an insulated rail joint, is a complex problem; there are only limited analytical, numerical and experimental studies available on this problem in the academic literature. This paper describes experimental and numerical investigations of railhead strains in the vicinity of the edge under the contact of a loaded wheel. A full-scale test rig was developed to cyclically apply wheel/rail rolling contact load to the edge zone of the railhead. An image analysis technique was employed to determine the railhead vertical, lateral and shear strain components. The vertical strains determined using the image analysis method have been validated with the strain gauge measurements and used for the calibration of a 3D nonlinear Finite Element Model (FEM) that simulates the wheel/rail contact at the railhead edge and use suitable boundary conditions commensurate to the experimental setup. The FEM was then used to determine other states of strains.     

Infrared spectroscopy combined with imaging: A new developing analytical tool in health and plant science

Modern infrared (IR) spectroscopy and imaging has a wide range of applications in health and plant sciences. Initially, it was extensively used for the study of proteins, nucleotides, lipids and carbohydrates. With time, its use has extended to disease assessment to discriminate healthy and diseased samples on the basis of chemical changes. The application of an advanced focal plane array detector, which is able to scan a large area of samples in a short time, helps in investigating specific changes that could be correlated with different environmental stresses. An IR microscope connected with a synchrotron light source further enhances the lateral spatial resolution at diffraction limit because of the compact beam size. For example, synchrotron-based IR spectroscopy imaging in combination with multivariate statistical analysis has been proven to be a powerful non-destructive analytical tool to probe changes in plant cell wall composition/structure in response to biological processes and environmental stresses. New development of nano-Fourier transform infrared spectroscopy (FTIR) combined with scattering type scanning near-field optical microscopy breaks the diffraction limitation, which opens the new area of applications. This review focuses on a new area of diagnostic research as well as development of IR spectroscopy and imaging for biological specimens including compositional changes in plant cell wall.     

X-ray crystal structure and spectroscopy of a pseudo-square pyramidal Cu(II) complex, trans-dinitratotetrakis (trans-4-styrylpyridine)copper(II)

Single crystals of the title Cu(II) complex, [Cu(stpy)₄(ONO₂)(ONO₂)] [stpy = trans-4-styryl-pyridine] have been prepared and characterized by elemental and thermal analyses, IR, electronic and EPR spectral measurements, and X-ray crystal structure determination. The complex crystallizes in the monoclinic space group P2₁/c with unit-cell parameters, a = 12.985(2), b = 22.865(8), c = 17.024(10) Å, = 112.29(3)°, and Z = 4. The structure consists of discrete monomeric units of [Cu(stpy)₄(ONO₂)(ONO₂)]. The equatorial positions of the Cu(II) polyhedron are occupied by nitrogen atoms of the four stpy ligands and the axial positions by the oxygens of two unidentate nitrate anions. One of these oxygens is at rather longer distance [2.609(3) Å] and may be considered to be semicoordinated. If this semibond is ignored, the coordination geometry lies closer to an idealized square pyramid than to the trigonal bipyramid geometry. IR spectra reveal nitrogen coordination from stpy and asymmetry in the monodentate oxygen binding of the two nitrate ligands. The optical reflectance band at 600 nm suggests pseudo-square-based pyramidal geometry around Cu(II). Well-resolved Cu(II) hyperfine features in the EPR spectra reveal the absence of exchange interactions between adjacent copper centers. Optical and EPR spectra of a methanolic solution of the complex indicate solvent interactions. Thermogravimetric analysis shows the complex to be stable up to 175°C.     

Photoproduction of iodine with nanoparticulate semiconductors and insulators

The crystal structures of different forms of TiO2 and those of BaTiO3, ZnO, SnO2, WO3, CuO, Fe2O3, Fe3O4, ZrO2 and Al2O3 nanoparticles have been deduced by powder X-ray diffraction. Their optical edges have been obtained by UV-visible diffuse reflectance spectra. The photocatalytic activities of these oxides and also those of SiO2 and SiO2 porous to oxidize iodide ion have been determined and compared. The relationships between the photocatalytic activities of the studied oxides and the illumination time, wavelength of illumination, concentration of iodide ion, airflow rate, photon flux, pH, etc., have been obtained. Use of acetonitrile as medium favors the photogeneration of iodine.     

Thermal and ion-exchange studies on chelating terpolymer resins derived from o cresol urea formaldehyde

Terpolymers prepared by condensation of o cresol and urea with formaldehyde in presence of acid catalyst (2 M HCl) proved to be selective chelating ion exchange resins for certain metal ions. The molecular weights of the synthesised terpolymers were determined by GPC Technique. TGA analysis was employed to study the thermal stability and the kinetic data like activation energy of the terpolymer resins. Chelation ion exchange properties of these terpolymers were studied for Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Cd²⁺ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer samples. The study was carried out over a wide pH range and in media of various ionic strengths.     

Acid catalysis in the N-bromosuccinimide-propargyl alcohol reaction

The reaction of N-bromosuccinimide (NBS) with propargyl alcohol in aqueous acidic medium is hydroxybromination. It is first order with respect to NBS, propargyl alcohol and H⁺, and inverse first order with respect to succinimide. The kinetic results point to solvated bromonium ion as the reactive species.     

Green Synthesis of Silver Nanoparticles Using Arachis hypogaea (Ground Nut) Root Extract for Antibacterial and Clinical Applications

The present study focused on the green synthesis of silver nanoparticles (AgNPs) using Arachis hypogaea (ground nut) root extract for the antibacterial and clinical application. The presence of major phytochemical compounds are found to be 2H-Pyaran,2,5-diethenyltetrahydro, Didodecyl phthalate, Decanoic acid, Tetradecanoic acid, Bis(2-ethylhexyl) phthalate, Dodecanoic acid, Phosphonic acid, 2-(4-Methoxyphenyl)-5-(4-methoxynaphthyl) thiophene and Methyl 2-(N-Benzylimino)-4-chloro-3,3-dimethylbutanoate by GC–MS. Nanoparticles synthesis is confirmed by UV–Vis analysis by observing the maximum absorption spectrum at 450 nm. XRD and SEM–EDX results reveals the synthesized nanoparticles are cubic crystalline with agglomerated particles of silver oxide with biomolecules present around it. TEM images clearly shows that the biosynthesized nanoparticles are mostly spherical and irregular shaped with an average particles size of 30 nm. Highest susceptibility pattern of silver nanoparticle against Enterococcus sp. (35 ± 0.4 mm) which followed by Pseudomonas sp. (33 mm) and Staphylococcus aureus (29 mm). Green synthesized nanoparticles are coated over the commercially available clinical band aid cloth by dip coating method. Silver nanoparticle incorporated band aid cloth showed good antibacterial activity against the harmful bacteria which usually cause infection and interfere during wound healing. Our findings revealed that green nanoparticle has a good antibacterial action against harmful bacteria and showed good response for efficient clinical application.     

Attenuation studies near K-absorption edges using Compton scattered <Superscript>241</Superscript>Am gamma rays

We have carried out photon attenuation measurements at several energies in the range from 49.38 keV to 57.96 keV around the K-absorption edges of the rare earth elements Sm, Eu, Gd, Tb, Dy and Er using 59.54 keV gamma rays from ²⁴¹Am source after Compton scattering from an aluminium target. Pellets of oxides of the rare earth elements were chosen as mixture absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. The scattered gamma rays were detected by an HPGe detector. The results are consistent with theoretical values derived from the XCOM package.