Light scattering studies on solutions of chlorinated rubber

Measurements have been made of the depolarisation factors \sigma u ,\sigma v ,\sigma h, and the intensity of scattering in the horizontal transverse direction, in the case of solutions of four different samples of chlorinated rubber in carbon tetrachloride. The size, shape and molecular weight of the micelles have been deduced by the application of the light scattering theories of Gans, Vrklajan and Katalinic and Debye. The extent to which the degradation of the rubber molecule occurs on chlorination has also been assessed.

Evidence for peroxide and Cul+ species in La1.8Sro.2Cu04 from photo-emission studies

Employing photo-emission and Auger electron spectroscopy, it is shown that La, ,Sr&uO,contains 0:- -typespeciesandCu'+ ions, proportionsof these speciesincrease with decreasing temperature. These species may play an important role in the high-temperature superconductivity of this oxide.

Indian developments in ultrasonics and acoustic emission methods

Fundamental investigations in ultrasonics in India date back to the early 20th century. But, fundamental and applied research in the field of nondestructive evaluation (NDE) came much later. In the last four decades it has grown steadily in academic institutions, national laboratories and industry. Currently, commensurate with rapid industrial growth and realisation of the benefits of NDE, the activity is becoming much stronger, deeper, broader and very wide spread. Acoustic Emission (AE) is a recent entry into the field of nondestructive evaluation. Pioneering efforts in India in AE were carried out at the Indian Institute of Science in the early 1970s. The nuclear industry was the first to utilise it. Current activity in AE in the country spans materials research, incipient failure detection, integrity evaluation of structures, fracture mechanics studies and rock mechanics. In this paper, we attempt to project the current scenario in ultrasonics and acoustic emission research in India.

Study of turbid media with light: Recovery of mechanical and optical properties from boundary measurement of intensity autocorrelation of light

We discuss the inverse problem associated with the propagation of the field autocorrelation of light through a highly scattering object like tissue. In the first part of the work, we reconstructed the optical absorption coefficient mu(u) and particle diffusion coefficient D-B from simulated measurements which are integrals of a quantity computed from the measured intensity and intensity autocorrelation g(2)(tau) at the boundary. In the second part we recover the mean square displacement (MSD) distribution of particles in an inhomogeneous object from the sampled g(2)(tau) measure on the boundary. From the MSD, we compute the storage and loss moduli distributions in the object. We have devised computationally easy methods to construct the sensitivity matrices which are used in the iterative reconstruction algorithms for recovering these parameters from the measurements. The results of the reconstruction of mu(a), D-B, MSD and the viscoelastic parameters, which are presented, show reasonable good position and quantitative accuracy.

Development of pseudo-two-dimensional turbulent wakes

Pseudotwo-dimensional wakes are generated by introducing spanwise cellular structures into an otherwise plane turbulent wake by means of the castellated blunt trailing edges of different configurations. The transverse growths of these coflowing cellular wakes are found to be independent of each other without any noticeable spanwise interaction. This wake growth is examined in the light of the plane equilibrium wake analysis. Though these wakes are not found to be exactly self-similar, their growth shows a nonmonotonous approach toward the asymptotic state appropriate to that of a plane wake. The dye emission in the wakes illustrated a coherent vortical structure in the transverse plane, similar to that of the usual two-dimensional wake, in spite of the initial spanwise irregularities.

Historical review of light scattering studies

This paper reviews the earlier experimental studies on light scattering in quartz near its phase transition, which ultimately laid the foundation for the basic concept of the soft mode. The theoretical work on the subject has been briefly referred to. A list of ferroelectrics in which soft mode studies have been carried out near TC using laser Raman spectroscopy is appended. Reference has also been made to the appearance of the central mode with abnormal increase in intensity at TC.

Excellent field emission from semialigned carbon nanofibers grown on cylindrical copper surface

We report the field emission from carbon nanofibers (CNFs) grown directly on cylindrical copper by a simple pyrolysis technique. The turn-on field is 0.17 V/µm and the emission current density is 0.9 mA/cm2 at 0.35 V/µm. The emission current is stable at a field of 0.35 V/µm and 6.5×10−6 Torr. The excellent field emission behavior is attributed to the sp2 phase in CNFs and the stable emission is due to the direct growth. The direct growth on cylindrical cathode is advantageous for field emission. ©2009 American Institute of Physics.

Synthesis of wurtzite-phase ZnS nanocrystal and its optical properties

The wurtzite phase of ZnS nanocrystal has been prepared by annealing in 200-600 degrees C temperature range, its cubic phase of 2-3 nm size. prepared through soft chemical method. Results of isochronal experiments of 2 h at different temperatures indicate that visible transformation to wurtzite from cubic ZnS appears at a temperature of 400 degrees C, which is about three times smaller than that of bulk ZnS phase transition temperature. The phases, nanostructures, and optical absorption characteristics are obtained through X-ray diffraction. transmission electron microscopy, and UV-visible absorption spectroscopy. A stable and green photoluminescence emission peaked at 518 nm is observed from the 600 degrees C annealed samples, under ultraviolet light excitation.

Vibration-rotation pattern in acetylene. II. Introduction of Coriolis coupling in the global model and analysis of emission spectra of hot acetylene around 3 mu m

A high temperature source has been developed and coupled to a high resolution Fourier transform spectrometer to record emission spectra of acetylene around 3 mu m up to 1455 K under Doppler limited resolution (0.015 cm(-1)). The nu(3)-ground state (GS) and nu(2)+nu(4)+nu(5)(Sigma(+)(u) and Delta(u))-GS bands and 76 related hot bands, counting e and f parities separately, are assigned using semiautomatic methods based on a global model to reproduce all related vibration-rotation states. Significantly higher J-values than previously reported are observed for 40 known substates while 37 new e or f vibrational substates, up to about 6000 cm(-1), are identified and characterized by vibration-rotation parameters. The 3 811 new or improved data resulting from the analysis are merged into the database presented by Robert et al. [Mol. Phys. 106, 2581 (2008)], now including 15 562 lines accessing vibrational states up to 8600 cm(-1). A global model, updated as compared to the one in the previous paper, allows all lines in the database to be simultaneously fitted, successfully. The updates are discussed taking into account, in particular, the systematic inclusion of Coriolis interaction.

Photocytotoxic 3d-Metal Scorpionates with a 1,8-Naphthalimide Chromophore Showing Photoinduced DNA and Protein Cleavage Activity

Ternary 3d-metal complexes of formulation [M(Tp(Ph))(py-nap)](ClO4)(1-3), where M is Co(II) (1), Cu(II) (2), and Zn(II) (3); Tp(Ph) is anionic tris (3-phenylpyrazolyl)borate; and py-nap is a pyridyl ligand with a conjugated 1,8-naphthalimide moiety, have been prepared from the reaction of metal perchlorate with KTp(Ph) and py-nap in CH2Cl2. The complexes have been characterized from analytical and physicochemical data. The complexes are stable in solution as evidenced from the electrospray ionization mass spectrometry data. The complexes show good binding propensity with calf thymus (CT) DNA, giving binding constant (K-b) values of similar to 10(5) M-1 and a molecular ``light-switch'' effect that results in an enhancement of the emission intensity of the naphthalimide chromophore on binding to CT DNA. The complexes do not show any hydrolytic cleavage of DNA. They show poor chemical nuclease activity in the presence of 3-mercaptopropionic acid or hydrogen peroxide (H2O2). The Co(II) and Cu(II) complexes exhibit oxidative pUC19 DNA cleavage activity in UV-A light of 365 rim. The Zn(II) complex shows moderate DNA photocleavage activity at 365 nm. The Cu(II)complex 2 displays photoinduced DNA cleavage activity in red light of 647.1 nm and 676 rim and near-IR light of >750 rim. A mechanistic studyin UV-A and visible light suggests the involvement of the hydroxyl radical as the reactive species in the DNA photocleavage reactions. The complexes also show good bovine serum albumin (BSA) protein binding propensity, giving K-BSA values of similar to 10(5) M-1. Complexes 1 and 2 display significant photoinduced BSA cleavage activity in UV-A light. The Co(II) complex 1 shows a significant photocytotoxic effect in HeLa cervical cancer cells on exposure to UV-A light of 365 nm, giving an IC50 value of 32 mu M. The IC50 value for the py-nap ligand alone is 41.42 mu m in UV-A light. The IC50 value is >200 mu M in the dark, indicating poor dark toxicity of 1. The Cu(II) complex 2 exhibits moderate photocytotoxicity and significant dark toxicity, giving IC50 values of 18.6 mu m and 29.7 mu m in UV-A light and in the dark, respectively.

CO2-laser induced X-ray emission from high density gaseous targets

A theory for the emission of X-rays from a high density gaseous plasma interacting with CO2 laser is given. It predicts a sharp increase in the X-ray intensity for densities close to the critical.

New light on the optical equivalence theorem and a new type of discrete diagonal coherent state representation

In many instances we find it advantageous to display a quantum optical density matrix as a generalized statistical ensemble of coherent wave fields. The weight functions involved in these constructions turn out to belong to a family of distributions, not always smooth functions. In this paper we investigate this question anew and show how it is related to the problem of expanding an arbitrary state in terms of an overcomplete subfamily of the overcomplete set of coherent states. This provides a relatively transparent derivation of the optical equivalence theorem. An interesting by-product is the discovery of a new class of discrete diagonal representations.

Radio frequency emission in electron beam-plasma and beam-beam interaction

A linear excitation of electromagnetic modes at frequencies (n + ı89 in a plasma through which two electron beams are contra-streaming along the magnetic field is investigated. This may be a source of the observed {cote emissions at auroral latitudes.

Theory of CO2-laser induced x-ray emission from high density gaseous targets

Abstract is not available.