Saturated high-repetition-rate 18.9-nm tabletop laser in nickellike molybdenum

We report saturated operation of an 18.9-nm laser at 5-Hz repetition rate. An amplification with a gain-length product GL of 15.5 is obtained in the 4d 1S0-4p 1P1 laser line of Ni-like Mo in plasmas heated at grazing incidence with approximately 1-J pulses of 8.1-ps duration from a tabletop laser system. Lasing is obtained over a broad range of time delays and pumping conditions. We also measure a GL of 13.5 in the 22.6-nm transition of the same ion. The results are of interest for numerous applications requiring high-repetition-rate lasers at wavelengths below 20 nm.     

Fatigue Effects in Elastic Materials with Variational Damage Models: A Vanishing Viscosity Approach

Journal of Nonlinear Science - We study the existence of quasistatic evolutions for a family of gradient damage models which take into account fatigue, that is the process of weakening in a...     

Fluorocompounds as antisolvents in hydrocarbons separation

The behaviour of perfluorotributylamine (FC43) with respect to hydrocarbons is investigated, and a comparison is made with perfluorocyclic oxide. The results obtained suggest the use of these fluorocompounds, especially of FC75, as antisolvents, in conjunction with a polar solvent, in the liquid-liquid extraction of hydrocarbons, particularly for the separation of aroma$\text{t}$ics from cycloparaffins.     

Raman investigation of the drawing effects on Ge-doped fibers

We have investigated the Raman activity of various germanosilicate fibers and their associated preforms. Our data indicate an enhancement in small rings' (3-member rings) concentration in the silica-based matrix of the fibers during the drawing process. The generation of such rings appears compatible with an increase of the sample density and fictive temperature. The data regarding the drawing effects on the fiber stress appear less clear, and it is possible to suggest that in some cases the drawing could lower the tensile stress. Finally we have also provided evidence that changing the drawing conditions within the usual range of application leads to no significant changes of the matrix structure as can be observed using Raman spectroscopy.     

Further advances on low-energy lunar impact dynamics

We extend the analysis, started in a previous work [1], concerning the formation of lunar impact craters due to low-energy trajectories. First, we adopt the Circular Restricted Three-Body Problem and consider different choices of initial conditions inside the stable invariant manifold associated with the central invariant one in the neighborhood of the L₂ equilibrium point in the Earth-Moon system. Then we move to the Bicircular Restricted Four-Body Problem to study the effect of the Sun on the distribution of impacts on the Moon’s surface.     

Hydrothermal ageing of radiation cured epoxy resin-polyether sulfone blends as matrices for structural composites

The hydrothermal ageing of epoxy-thermoplastic blends, used as matrices for carbon fibre composites, cured by electron beam, has been studied. Two different thermoplastic percentages have been adopted. A suitable choice of both curing process and formulation parameters allows to carry out irradiation at mild temperature with several advantages, coming from a “non thermal” process, for both the final properties of the materials and the environment. Nevertheless the occurring of vitrification phenomena needs the use of a short thermal treatment after irradiation on the already solid materials, in order to complete the cure reactions. Radiation cured epoxy based matrices have been subjected to a thermal and moisture absorption ageing treatment and its influence on the thermal and mechanical properties has been investigated through dynamic mechanical thermal analysis and fracture toughness tests. The results have been interpreted on the basis of the different curing degree reached by the investigated systems and in the light of their morphological structures. Plasticization, thermal curing and degradation reactions occur in different extent depending on the kind of the material. In particular, for fracture properties, a better resistance to ageing is shown by the system at higher thermoplastic concentration.     

Enantioselective Cytotoxicity of Chiral Diphosphine Ruthenium(II) Complexes Against Cancer Cells

The chiral cationic complex [Ru(η¹-OAc)(CO)((R,R)-Skewphos)(phen)]OAc ( 2 ^R ), isolated from reaction of [Ru(η¹-OAc)(η²-OAc)(R,R)-Skewphos)(CO)] ( 1 ^R ) with phen, reacts with NaOPiv and KSAc affording [RuX(CO)((R,R)-Skewphos)(phen)]Y (X=Y=OPiv 3 ^R ; X=SAc, Y=OAc 4 ^R ). The corresponding enantiomers 2 ^S - 4 ^S have been obtained from 1 ^S containing (S,S)-Skewphos. Reaction of 2 ^R and 2 ^S with (S)-cysteine and NaPF₆ at pH=9 gives the diastereoisomers [Ru((S)-Cys)(CO)(PP)(phen)]PF₆ (PP=(R,R)-Skewphos 2 ^R -Cys; (S,S)-Skewphos 2 ^S -Cys). The DFT energetic profile for 2 ^R with (S)-cysteine in H₂O indicates that aquo and hydroxo species are involved in formation of 2 ^R -Cys. The stability of the ruthenium complexes in 0.9 % w/v NaCl solution, PBS and complete DMEM medium, as well as their n-octanol/water partition coefficient (logP), have been evaluated. The chiral complexes show high cytotoxic activity against SW1736, 8505 C, HCT-116 and A549 cell lines with EC₅₀ values of 2.8–0.04 μM. The (R,R)-Skewphos derivatives show higher cytotoxicity compared to their enantiomers, 4 ^R (EC₅₀=0.04 μM) being 14 times more cytotoxic than 4 ^S against the anaplastic thyroid cancer 8505 C cell line.     

Leaving and reaching the moon from a libration point orbit

We represent the Earth–Moon system as a Circular Restricted Three–Body Problem and we look for trajectories which allow the departure from the lunar surface and which might have played a role in the formation of impact craters. We take advantage of the central and hyperbolic invariant manifolds which exist in the neighbourhood of the collinear equilibrium points L₁ and L₂. Different types of semi–analytical and numerical methodologies are exploited. The most meaningful results are pointed out. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)