Femtosecond laser ablation of neurons in <Emphasis Type="Italic">C</Emphasis>. <Emphasis Type="Italic">elegans</Emphasis> for behavioral studies

In this paper, the interaction between the inhomogeneous and anisotropic cloak covered infinitely long PEC circular cylinder and the parallel electric-line-source is investigated in detail. First, the permittivity and permeability tensors of the cloak are defined according to Pendry’s model, then the wave equation in the metamaterial cloak is derived; second, the far/near properties of the model are investigated, and using the boundary conditions the electromagnetic fields of the whole region are calculated analytically; finally, based on the analytical expressions, the electric fields of the whole region are demonstrated through numerical results which show the effects of invisibility. Finally, the effects of loss on the performance of the invisible cloak are investigated.     

Resonant parameters of <Superscript>5</Superscript>He and <Superscript>5</Superscript>Li states and nucleon-α scattering

A new method of analysis of resonant parameters in the framework of the J-matrix inverse scattering formalism is proposed. The method is applied to analysis of Nα scattering in various partial waves. The obtained 1/2^? and 3/2^? resonance energies and widths in ⁵He and ⁵Li nuclei are in good agreement with the results of other approaches. The eigenenergies entering the J-matrix phase shift parameterization are shown to correlate well with the respective results of no-core shell model calculations, in particular, in the case of non-resonant s-wave scattering.     

Dynamics and control of underactuated mechanical systems: analysis and simple experimental verification

Underactuated mechanical systems are systems with fewer control inputs than the degrees of freedom, m < n, the relevant technical examples being e.g. cranes, aircrafts and flexible manipulators. The determination of an input control strategy that forces an underactuated system to complete a set of m specified motion tasks (servo-constraints) is a demanding problem. The solution is conditioned to differential flatness of the problem, denoted that all 2n state variables and m control inputs can algebraically be expressed, at least theoretically, in terms of the desired m outputs and their time derivatives up to a certain order. A more practical formulation, motivated hereafter, is to pose the problem as a set of differential-algebraic equations, and then obtain the solution numerically. The theoretical considerations are illustrated by a simple two-degree-of-freedom underactuated system composed of two rotating discs connected by a flexible rod (torsional spring), in which the pre-specified motion of the first disc is actuated by the torque applied to the second disc, n = 2 and m = 1. The determined control strategy is then verified experimentally on a laboratory stand representing the two-disc system. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Transitional intermittency in a rough wall boundary layer

The transitional intermittency factor distributions were evaluated from the wall friction records acquired in the rough wall boundary layer under free stream turbulence. Important characteristics of by-pass transition were derived from the factor distributions. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation of the effect of the wall roughness and free stream turbulence on the boundary layer development

Development of a flat plate boundary layer (grad P = 0) was investigated in the closed type wind tunnel (0.5 × 0.9 × 2.7 m³). The plate was either aerodynamically smooth or covered with a thin plate (10 mm thick) with the surface made from the sand paper (grits 80). FST is generated by square mesh plane grids/screens set across the flow as to produce homogeneous, close to isotropy turbulence with various scales of velocity and length. The surface roughness was of transient type. The comparison is made of the effect of various grouping of the wall roughness and FST on the boundary layer development. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Metallic hydrogen with a strong electron–phonon coupling at a pressure of 300–500 GPa

Atomic metallic hydrogen, which has a lattice with the FDDD unit cell symmetry, has been shown to be a stable phase at a hydrostatic pressure of 350–500 GPa. The found structure has a phonon spectrum which is stable with respect to decay. The structural, electronic, phonon, etc., characteristics of normal metallic phases of hydrogen at a pressure of 350–500 GPa have been ab initio calculated.     

Elastic and photo-elastic characteristics of laser crystals potassium rare-earth tungstates KRE(WO4)2, where RE = Y,Yb, Gd and Lu

The elastic and photo-elastic characteristics of four laser crystals KY(WO₄)₂, KGd(WO₄)₂, KYb(WO₄)₂, and KLu(WO₄)₂ are presented. The first pair was reported early, and the last two materials have been investigated for the first time. The full matrix of elastic constants of these monoclinic crystals has been determined. Also, acousto-optical figure of merit for all the basic geometries of isotropic diffraction has been measured. It is proved that potassium rare-earth tungstates has rather good acousto-optical properties and particularly can take place of fused silica in technical applications required high power laser radiation. All the results demonstrate good prospect of these optically bi-axial laser crystals for development of new effective acousto-optical devices.     

Single molecule imaging of oxygenation of cobalt octaethylporphyrin at the solution/solid interface: thermodynamics from microscopy

For the first time, the pressure and temperature dependence of a chemical reaction at the solid/solution interface is studied by scanning tunneling microscopy (STM), and thermodynamic data are derived. In particular, the STM is used to study the reversible binding of O(2) with cobalt(II) octaethylporphyrin (CoOEP) supported on highly oriented pyrolytic graphite (HOPG) at the phenyloctane/CoOEP/HOPG interface. The adsorption is shown to follow the Langmuir isotherm with P(1/2)(298K) = 3200 Torr. Over the temperature range of 10-40 °C, it was found that ΔH(P) = -68 ± 10 kJ/mol and ΔS(P) = -297 ± 30 J/(mol K). The enthalpy and entropy changes are slightly larger than expected based on solution-phase reactions, and possible origins of these differences are discussed. The big surprise here is the presence of any O(2) binding at room temperature, since CoOEP is not expected to bind O(2) in fluid solution. The stability of the bound oxygen is attributed to charge donation from the graphite substrate to the cobalt, thereby stabilizing the polarized Co-O(2) bonding. We report the surface unit cell for CoOEP on HOPG in phenyloctane at 25 °C to be A = (1.46 ± 0.1)n nm, B = (1.36 ± 0.1)m nm, and α = 54 ± 3°, where n and m are unknown nonzero non-negative integers.