The sorption of CO and O on Ni (111) studied by leed and iss

The adsorption of CO and O on Ni (111) was studied by low-energy ion scattering (ISS) and low-energy electron diffraction (LEED). For the ordered (√7/2) × (√7/2) R19.1° CO layer ion scattering gives a coverage greater than $\text{1}\text{2}$ monolayer, and for the (2 × 2) O layer a coverage of $\text{1}\text{4}$ monolayer. The CO is non-dissociatively adsorbed, with the C bound to the Ni. The molecules are oriented parallel to the surface normal. Island formation at lower CO coverages is possible.     

Über den Untergruppenverband einer Abelschen Operatorgruppe Teil I: m-Verbände

Ohne Zusammenfassung     

Active mode locking of a phase-conjugating SBS-laser oscillator

We present a flashlamp-pumped Nd:YAG laser simultaneously emitting pulse structures on microsecond, nanosecond and picosecond time scales. Within a microsecond flashlamp pump pulse a nonlinear reflector based on stimulated Brillouin scattering (SBS) generates several Q-switch pulses. The phase-conjugating effect of the SBS reflector provides a compensation of phase distortions generated inside the laser rod, resulting in transverse fundamental mode operation. Additional acousto-optic loss modulation inside the resonator leads to mode locking. As a result, each Q-switch pulse is subdivided into several picosecond pulses. Energies of up to 2 mJ for the mode-locked pulses with durations between 220 and 800 ps are demonstrated. The wide variability of the lasers temporal output parameters as well as its high beam quality make it a splendid tool for fundamental research in laser materials processing. PACS 42.60.Fc; 42.60.Gd; 42.65.Es     

Review of the book <Emphasis Type="Italic">Optics of Microstructured Fibers</Emphasis> by A.M. Zheltikov (Nauka,Moscow, 2004)

Chronicle

Review of the book Optics of Microstructured Fibers by A.M. Zheltikov (Nauka, Moscow, 2004)     

Nanotube molecular transporters: internalization of carbon nanotube-protein conjugates into Mammalian cells

The interactions between various functionalized carbon nanotubes and several types of human cancer cells are explored. We have prepared modified nanotubes and have shown that these can be derivatized in a way that enables attachment of small molecules and of proteins, the latter through a novel noncovalent association. The functionalized carbon nanotubes enter nonadherent human cancer cells as well as adherent cell lines (CHO and 3T3) and by themselves are not toxic. While the fluoresceinated protein streptavidin (MW approximately 60 kD) by itself does not enter cells, it readily enters cells when complexed to a nanotube-biotin transporter and exhibits dose-dependent cytotoxicity. The uptake pathway is consistent with adsorption-mediated endocytosis. The use of carbon nanotubes as molecular transporters could be exploited for various cargos. The biocompatibility and unique physical, electrical, optical, and mechanical properties of nanotubes provide the basis for new classes of materials for drug, protein, and gene delivery applications.     

Ultrasensitive ATP detection using firefly luciferase entrapped in sugar-modified sol-gel-derived silica

Firefly luciferase (FL) was entrapped in sol-gel-derived silica containing precursors based on covalent linkage of d-gluconolactone or d-maltonolactone to (aminopropyl)triethoxysilane to form N-(3-triethoxysilylpropyl)gluconamide or N-(3-triethoxysilylpropyl)maltonamide. The enzyme was active and stable in this material and showed catalytic constants close to those in solution. As little as 20 amol ATP could be detected with the entrapped FL, and the entrapped enzyme could be used over several cycles.     

Laboratory Intercomparison on the Determination of the Fe(II)/Fe(III) Ratio in Glass Using Mössbauer Spectroscopy

A Perturbed Angular Correlation (PAC) study was performed on the system that presents a rich variety of structural and magnetic phase transitions as a function of the oxygen content (δ) or as a function of temperature (T). The PAC signal at room temperature allowed the determination of the Electrical Field Gradient (EFG) parameters and to correlate them with the lattice average symmetry namely the orthorhombic (O′ or O*) Pbnm and rhombohedral (R) phases measured by X-ray diffraction.     

The dynamics of spatiotemporal modulations

The modulational instability of traveling waves is often thought to be a crucial point in the mechanism of transition to space-time disorder and turbulence. The aim of this paper is to study the effect of spatiotemporal modulations on some dynamics u(0)(x,t), which may occur as an instability process when a control parameter varies, for instance. We analyze the properties of the modulated dynamics of the form g(1)(x)g(2)(t)u(0)(x,t) compared to those of the reference dynamics u(0)(x,t), using operator theory. We show that, if the reference dynamics is invariant under some space-time symmetry in the sense of Ref. [J. Nonlinear Sci. 2, 183 (1992)], the modulation has the effect of either deforming this symmetry or breaking it, depending on whether the corresponding operator remains unitary or not. We also demonstrate that the smallest Euclidean space containing the modulated dynamics has a dimension smaller than or equal to the smallest Euclidean space containing u(0)(x,t). The previous results are then applied to the case of modulated uniformly traveling waves. While the spatiotemporal translation invariance of the wave never persists in the presence of a modulation, the existence of a spatiotemporal symmetry depends on the resonance of the Fourier sidebands due to the modulation. In case of nonresonance, a spatiotemporal symmetry exists and is explicitly determined. In this situation, the modulated wave and the carrier wave have the same spectrum (up to a normalization factor), the same entropy, and the spatial (resp., temporal) two-point correlation is deformed only by the spatial (resp., temporal) modulation. (c) 1995 American Institute of Physics.     

Study of the Drying Behavior of Poly(vinyl alcohol) Aqueous Solution

This paper deals with the drying behavior of poly(vinyl alcohol) aqueous solution containing an active substance and placed into a Petri box. The objective is to reduce the drying time while respecting some constraints. To succeed, it is important to understand complex mechanisms governing heat and mass transfers. During the drying, the product thickness shrinks and its properties evolve. Drying kinetics in convective and infrared radiation are presented.