Molecular Physics

Stimulated Raman scattering (SRS) microscopy has opened up a wide range of biochemical imaging applications by probing a particular Raman-active molecule vibrational mode in the specimen. However, the original implementation with picosecond pulse excitation can only realize rapid chemical mapping with a single Raman band. Here we present a novel SRS microscopic technique using a grating-based pulse shaper for excitation and a grating-based spectrograph for detection to achieve simultaneous multicolor SRS imaging with high sensitivity and high acquisition speeds. In particular, we use a linear combination of the measured CH2 and CH3 stretching signals to map the distributions of protein and lipid contents simultaneously.

Phenylhydrazine (PHZ), a potent chemical causes toxicity on various tissues at various levels. Administration of phenylhydrazine mainly causes haematotoxicity which leads to the haemolytic anemia. In mammals PHZ induced anemia increased the iron absorption in spleen, liver and duodenum and finally iron metabolism was altered. Local demand and supply of Fe would increase erythropoeitic activity of the spleen so the size of spleen was increased that create the splenomegaly. PHZ induced anemia activate immune response which triggers phagocytosis in the spleen and liver. Apart from this administration of PHZ interfere the binding of erythropoietin (EPO) with erythropoietin receptors (EPOR) so that JAK-STAT would be affected.PHZ also showed genotoxic effect by creating single strand DNA damage.

It is shown that the nonlinear equations governing the dynamics of the large amplitude waves in a self-gravitating unmagnetized collisionless dust-electron-ion plasma admit stationary dust-acoustic shock solutions. Owing to the adiabaticity of dust-charge variation, inclusion of self-gravitation, and to the departure from the so-called Botzmannian electrons and ions to the trapped electrons and nonthermal ions, the dynamics of the nonlinear wave is found to be governed by a new energy-like integral equation.

High temperature superconductivity emerges in the cuprate compounds upon changing the electron density of an insulator in which the electron spins are antiferromagnetically ordered. A key characteristic of the superconductor is that electrons can be extracted from them at zero energy only if their momenta take one of four specific values (the `nodal points'). A central enigma has been the evolution of the zero energy electrons in the metallic state between the antiferromagnet and the superconductor, and recent experiments yield apparently contradictory results. The oscillation of the resistance in this metal as a function of magnetic field indicate that the zero energy electrons carry momenta which lie on elliptical `Fermi pockets', while ejection of electrons by high intensity light indicates that the zero energy electrons have momenta only along arc-like regions. We present a theory of new states of matter, which we call `algebraic charge liquids', which arise naturally between the antiferromagnet and the superconductor, and reconcile these observations. Our theory also explains a puzzling dependence of the density of superconducting electrons on the total electron density, and makes a number of unique predictions for future experiments.

Theories based on the coupling between spin fluctuations and fermionic quasiparticles are among the leading contenders to explain the origin of high-temperature superconductivity, but estimates of the strength of this interaction differ widely. Here we analyze the charge- and spin-excitation spectra determined by angle-resolved photoemission and inelastic neutron scattering, respectively, on the same crystals of the high-temperature superconductor YBa2Cu3O6.6. We show that a self-consistent description of both spectra can be obtained by adjusting a single parameter, the spin-fermion coupling constant. In particular, we find a quantitative link between two spectral features that have been established as universal for the cuprates, namely high-energy spin excitations and "kinks" in the fermionic band dispersions along the nodal direction. The superconducting transition temperature computed with this coupling constant exceeds 150 K, demonstrating that spin fluctuations have sufficient strength to mediate high-temperature superconductivity.

The design of a new apparatus, named FANTASIO, for studying jet-cooled molecules is described. It includes, around the same supersonic expansion cell, a high resolution Fourier transform spectrometer with single or multipass optics, a tunable diode laser spectrometer with optional cavity ring-down facilities, and a quadrupole mass spectrometer. Performance and operational procedures are illustrated.

The comprehensions of Roger Boscovich (1711-1787) concerning the structure of fluids have been further developed applying the achievements and the results of modern science. It is shown that various supermolecular rotating particles (molecular pairs, bimolecules and oligomolecules) exist in compressed gases and liquids. The volumes occupied by rotating particles are equal to the volumes of substances at the critical point (molecular pairs), co-volume of van der Waals equation (bimolecules), and volume of solid phase at triple point (oligomolecules). A mathematical model that enables the calculation of these volumes as well as their fractions in liquids was developed. The importance of the supermolecular structure of olefins and vinyl monomers for their polymerization is presented.

Од теорије Руђера Бошковића (18. в.) до теорије Павла Савића и Радивоја Кашанина (20. в.) је раздобље од два века. Прва теорија се темељи на закону континуитета и полази од начела класичне Њутновое механике, а друга се заснива на квантној механици. Уз то, Бошковић је свој закон сила примењивао углавном на примарне елементе материје (непротежне и недељиве тачке), као и на честице првог и другог реда, а Савић и Кашанин се усредсређују на честице „од атома до небеских тела“. Стога се чини да су теоријски приступи и предмети ове две теорије потпуно различити. Међутим, није тако. У овом раду дајемо кратке описе живота наведених научника и указујемо на историјску повезаност ове две теорије, као и да теорија Савић-Кашанин заправо произилази из Бошковићеве теорије. Након што смо потврдили да резултати савремене науке потврђују исправност обе теорије, користимо их као путоказе за изналажење неких нових непознатих закономерности у природи.

The nonlinear aspects of longitudinal motion of interacting point masses in a lattice are revisited, with emphasis on the paradigm of charged dust grains in a dusty plasma (DP) crystal. Different types of localized excitations, predicted by nonlinear wave theories, are reviewed and conditions for their occurrence (and characteristics) in DP crystals are discussed. Making use of a general formulation, allowing for an arbitrary (e.g. the Debye electrostatic or else) analytic potential form $\phi(r)$ and arbitrarily long site-to-site range of interactions, it is shown that dust-crystals support nonlinear kink-shaped localized excitations propagating at velocities above the characteristic DP lattice sound speed v 0. Both compressive and rarefactive kink-type excitations are predicted, depending on the physical parameter values, which represent pulse- (shock-)like coherent structures for the dust grain relative displacement. Furthermore, the existence of breather-type localized oscillations, envelope-modulated wavepackets and shocks is established. The relation to previous results on atomic chains as well as to experimental results on strongly-coupled dust layers in gas discharge plasmas is discussed.

We report on a delayed-choice quantum eraser experiment based on a two-photon imaging scheme using entangled photon pairs. After the detection of a photon which passed through a double-slit, a random delayed choice is made to erase or not erase the which-path information by the measurement of its distant entangled twin; the particle-like and wave-like behavior of the photon are then recorded simultaneously and respectively by one set of joint detection devices. Unlike all previous experiments the present work takes advantage of two-photon imaging. The complete which-path information of a photon is transferred to its distant entangled twin through a "ghost" image. The choice is made on the Fourier transform plane of the ghost image between reading "complete information" or "partial information" of the double-path.

A series of multiple nanosecond molecular dynamics simulations has been carried out for a dipalmitoylphosphatidylcholine lipid bilayer system in water solution, with ubiquinone (UQ) freely moving inside the bilayer. The focus is on the mobility and the preferential positions ...

Hanson, GR, Noble, CJ, Gates, KE, Burrage, K., Smith, CD and Bottle, SE (2001). Xsophe, a computer simulation software suite for the analysis of CW EPR spectra. Application to the analysis of mono-, diand tri-nitroxide EPR spectra. In: , 3rd International Conference on Nitroxide Radicals. 3rd International Conference on Nitroxide Radicals, Universitat Kaiserslautern, (54-54). 23-29 September 2001.

In this paper we write down equations of motion (following the approach pioneered by Hoover) for an exact isothermal-isobaric molecular dynamics simulation, and we extend them to multiple thermostating rates, to a shape-vary-ing cell and to molecular systems, ...