Ultrafast absorption kinetics of NADH in folded and unfolded conformations

The non-radiative energy transfer is shown to occur on a ~3ps time scale for NADH in the folded form in H2O. Addition of methanol thermodynamically favours the open form, for which energy transfer does not occur

Picosecond and Nanosecond Components in Bacteriorhodopsin Light-Induced Electric Response Signal

Numerous investigations on the primary events of the bacteriorhodopsin photocycle indicate that the first steps of the energy transformation process take place in the 500 fs-5 ps region. These processes are known to be followed by others in the μs and ms regions. Recent observations indicate also the existence of nanosecond intermediate(s). Here we are reporting on direct measurements of the light-induced electric response signal of purple membrane carried out in the ps and ns regions. The laser flash-induced electric response of dried oriented purple membrane samples were detected by an ultrafast sampling oscilloscope. The measured kinetic curves were analyzed by exponential fitting and by a simulation-optimization method taking into account the time characteristics of the measuring setup. This analysis revealed a two phase real charge separation process. The first phase (tau = 21±2 ps) coincides well with the overall bR-[unk] K transition. The second phase (tau = 6±0.5 ns) can be correlated with the nanosecond optical transitions reported by several workers, or may be an optically silent charge movement inside the protein moiety or on the surface of the membrane

Variational approach in dislocation theory

A variational approach is presented to calculate the stress field generated by a system of dislocations. It is shown that in the simplest case, when the material containing the dislocations obeys Hooke's law the variational framework gives the same field equations as Kr\"oner's theory. However, the variational method proposed allows to study many other problems like dislocation core regularisation, role of elastic anharmonicity and dislocation--solute atom interaction. The aim of the paper is to demonstrate that these problems can be handled on a systematic manner.Comment: 16 pages, 4 figures. Minor changes in the text and few numerical corrections. Few references also adde

Fluorescence kinetics of flavin adenine dinucleotide in different microenvironments

Fluorescence kinetics of flavin adenine dinucleotide was measured in a wide time and spectral range in different media, affecting its intra- end extramolecular interactions, and analyzed by a new method based on compressed sensing

Global existence for a system of non-linear and non-local transport equations describing the dynamics of dislocation densities

In this paper, we study the global in time existence problem for the Groma-Balogh model describing the dynamics of dislocation densities. This model is a two-dimensional model where the dislocation densities satisfy a system of transport equations such that the velocity vector field is the shear stress in the material, solving the equations of elasticity. This shear stress can be expressed as some Riesz transform of the dislocation densities. The main tool in the proof of this result is the existence of an entropy for this syste

Intermittent dislocation flow in viscoplastic deformation

The viscoplastic deformation (creep) of crystalline materials under constant stress involves the motion of a large number of interacting dislocations. Analytical methods and sophisticated `dislocation-dynamics' simulations have proved very effective in the study of dislocation patterning, and have led to macroscopic constitutive laws of plastic deformation. Yet, a statistical analysis of the dynamics of an assembly of interacting dislocations has not hitherto been performed. Here we report acoustic emission measurements on stressed ice single crystals, the results of which indicate that dislocations move in a scale-free intermittent fashion. This result is confirmed by numerical simulations of a model of interacting dislocations that successfully reproduces the main features of the experiment. We find that dislocations generate a slowly evolving configuration landscape which coexists with rapid collective rearrangements. These rearrangements involve a comparatively small fraction of the dislocations and lead to an intermittent behavior of the net plastic response. This basic dynamical picture appears to be a generic feature in the deformation of many other materials. Moreover, it should provide a framework for discussing fundamental aspects of plasticity, that goes beyond standard mean-field approaches that see plastic deformation as a smooth laminar flow

Ways of enhancement of the surgical treatment efficacy in treatment of patients, suffering pulmonary tumors

Objective. Efficacy of endoscopic bronchosanation for prophylaxis of preoperative and postoperative complications in patients with pulmonary tumors. Маterials and methods. There was studied the efficacy of endoscopic photodynamic therapy in accordance to procedure, elaborated by the authors, including injection of the water solution of a methylene blue dye in concentration 0.04% into tracheobronchial tree, irradiated by laser with the wave length 0.63 mcm, independently and in conjunction with a standard anti-inflammatory therapy as preoperative preparation of tracheobronchial tree in patients, suffering pulmonary cancer. In the investigation 181 patients were included, suffering pulmonary cancer Stages II-III, morphologically confirmed, and with coexistent endobronchitis. Results. In accordance to analysis of the pathogenic microflora titer and character in lumen of bronchial tree after preoperative preparation there was established, that while application of independent endoscopic bronchosanation in 55 (87%) observations the pathogenic microflora was absent. While combination of photodynamical bronchosanation in accordance to standard therapy a pathogenic microflora was not revealed in 52 patients. While conduction of a standard preparation without application of a laser therapy microflora was not revealed only in 44.8% observations. Together with the bronchial mucosa metaplasia in some investigated patients the dysplastic changes of bronchial epithelium of various severity degree were registered. Independent endoscopic bronchosanation have leaded to trustworthy lowering of a general rate of the bronchial epithelial dysplasia in the patients tо 36.1%, together with standard anti-inflammatory therapy - tо 42.4%. Conclusion. Application of endoscopic photodynamic bronchosanation in accordance to the proposed procedure in preoperative period in the patients with objective to correct a concomitant endobronchitis, as independent option or together with standard anti-inflammatory therapy, leads to reduction  of the endobronchial complications rate after operative treatment for pulmonary cancer, comparing with a control group. Еndoscopic bronchosanation is accompanied by significant lowering of severity of endoscopic signs of coexistent endobronchitits and improvement of mucociliary transport. In accordance to microbiological tests in 87 - 88% of patients a complete sanation of bronchial tree and elimination of main histological criteria of inflammation were noted, while in 67.2 - 100% patients – restoration of normal structure of the bronchial tree mucosa

Nanocrystalline materials studied by powder diffraction line profile analysis

X-ray powder diffraction is a powerful tool for characterising the microstructure of crystalline materials in terms of size and strain. It is widely applied for nanocrystalline materials, especially since other methods, in particular electron microscopy is, on the one hand tedious and time consuming, on the other hand, due to the often metastable states of nanomaterials it might change their microstructures. It is attempted to overview the applications of microstructure characterization by powder diffraction on nanocrystalline metals, alloys, ceramics and carbon base materials. Whenever opportunity is given, the data provided by the X-ray method are compared and discussed together with results of electron microscopy. Since the topic is vast we do not try to cover the entire field