Octave-spanning carrier-envelope phase stabilized visible pulse with sub-3-fs pulse duration

The visible second harmonic of the idler output from a noncollinear optical parametric amplifier was compressed using adaptive dispersion control with a deformable mirror. The amplifier was pumped by and seeded in the signal path by a common 400 nm second-harmonic pulse from a Ti:sapphire regenerative amplifier. Thus, both the idler output and the second harmonic of the idler were passively carrier-envelope phase stabilized. The shortest pulse duration achieved was below 3 fs.     

Dual-oriented thin crystals of molybdenum grown under Ar+ ion bombardment

Ar⁺ sputtering of an Cu(111) surface while simultaneously supplying Mo atoms is known to induce an oriented growth of Mo thin crystals, or seed-layers, on evolving conical Cu protrusions. The seed-layers thus formed are shown to be dual-oriented, or bicrystalline, consisting of columnar crystallites grown homo-epitaxially. The orientation relationship between the two types of crystallites was (100)_I (111)_II with [001]_I [110]_II, and this bicrystallinity probably resulted from a non-uniform charge-up of the layers' growth front. As concluded from high-resolution electron microscopy, the Mo(100) stacking is elastically converted into the Mo(111) stacking and vice versa, under the influence of tensile stress. The homo-epitaxy that the seed-layers exhibited is believed to reflect the mutual convertibility of the Mo(100) and (111) stackings.     

Pseudogap formation in the intermetallic compounds (Fe1-xVx)3Al

Optical conductivity data of the intermetallic compounds (Fe1-xVx)3Al ( 0相似文献   

Mechanics of a particle near the center of a rotating ring

The equations of motion of a test particle moving near the center of a massive rotating ring are derived up to the post-post-Newtonian order of approximation, by using the metric tensor for many body system which is Minkowskian at spatial infinity. Logarithmic divergences due to self-interaction of the ring appear in the equations of motion. These divergences can be removed by the procedure which is similar to the renormalization method in particle physics. In the equations of motion there appears a force directing to the rotation axis and depending on the angular velocity of the ring. This force vanishes when the magnitude of the gravitational constant times the mass of the ring divided by the radius of the ring is about one tenth of the square of the velocity of light. Under this condition it is shown that the relative magnitude of the Coriolis force to the centrifugal force in the equations of motion agrees with the expected one from the equations of motion in a rotating reference frame.     

Approximate Solutions of the Dirac Equation for?the?Manning-Rosen Potential Including the?Spin-Orbit Coupling Term

The bound-state solutions of the Dirac equation for the Manning-Rosen potential are presented approximately for arbitrary spin-orbit quantum number κ. The energy eigenvalues and corresponding two-component spinors of the two Dirac particles are obtained in the closed form by using the framework of the spin symmetry and pseudospin symmetry concept. Two special cases κ=±1 and the Hulthén potential are briefly investigated.     

Oscillator strengths for singly ionized oxygen

The electric dipole oscillator strengths for multiplet and individual lines between some doublet and quartet levels have been calculated using the weakest bound electron potential model theory (WBEPMT) in singly ionized oxygen. We employed both numerical Coulomb approximation (NCA) wave functions and numerical non-relativistic Hartree-Fock (NRHF) wave functions for expectation values of radii in determination of parameters. The calculated oscillator strengths have been compared with available theoretical and experimental results. A good agreement with results in literature has been obtained. Moreover, oscillator strengths not existing in the literature for some highly excited levels have been obtained using this method. Electronic supplementary material  Supplementary Online Material     

Comparative studies of nontoxic and toxic amyloids interacting with membrane models at the air-water interface

Many in vitro studies have pointed out the interaction between amyloids and membranes, and their potential involvement in amyloid toxicity. In a previous study, we generated a yeast toxic mutant (M8) of the harmless model amyloid protein HET-s((218-289)). In this study, we compared the self-assembling process of the nontoxic wild-type (WT) and toxic (M8) protein at the air-water interface and in interaction with various phospholipid monolayers (DOPE, DOPC, DOPI, DOPS and DOPG). We first demonstrate using ellipsometry measurements and polarization-modulated infrared reflection absorption spectroscopy (PMIRRAS) that the air-water interface promotes and modifies the assembly of WT since an amyloid-like film was instantaneously formed at the interface with an antiparallel β-sheet structuration instead of the parallel β-sheet commonly observed for amyloid fibers generated in solution. The toxic mutant (M8) behaves in a similar manner at the air-water interface or in bulk, with a fast self-assembling and an antiparallel β-sheet organization. The transmission electron microscopy (TEM) images established the fibrillous morphology of the protein films formed at the air-water interface. Second, we demonstrate for the first time that the main driving force between this particular fungus amyloid and membrane interaction is based on electrostatic interactions with negatively charged phospholipids (DOPG, DOPI, DOPS). Interestingly, the toxic mutant (M8) clearly induces perturbations of the negatively charged phospholipid monolayers, leading to a massive surface aggregation, whereas the nontoxic (WT) exhibits a slight effect on the membrane models. This study allows concluding that the toxicity of the M8 mutant could be due to its high propensity to interact with membranes.     

Syntheses and magnetic properties of iron(III) complexes with imidazole groups

Iron(III) complexes with the general formula of [Fe (R-Himap)₂]X and [Fe(R-Himat)₂]X (Himap = shiff-base prepared from the condensation of 4-formylimidazole and 2-aminophenol, Himat = shiff base prepared from the condensation of 4-formylimidazole and 2-aminobenzenethiol, and R = H, Me, Ph; X = ClO₄, NO₃, BPh₄) have been synthesized. The complexes have an N₄O₂ donor set or an N₄S₂ donor set. These complexes have 5 and 5 member rings around an iron(III) atom per one chelate ring, that is, "5-5 member rings". The crystal structure, Mössbauer spectra, magnetic properties and absorption spectra of the complexes were examined. In addition, [Fe (Himsa)₂]ClO₄ having "5-6 member rings" of an N₄O₂ donor set and [Fe (Ph-Himap)(Ph-imap)] obtained by the deprotonation of [Fe (Ph-Himap)₂]ClO₄ have been also synthesized, and the Mössbauer spectra and magnetic properties of those complexes were examined. The X-ray structure of a single crystal of [Fe (Himap)₂]BPh₄ was determined: C₄₄H₃₆N₆BO₂Fe, triclinic, space group P(# 2), a = 12.452(2) Å, b = 12.748(2) Å, c = 11.996(2) Å, = 103.97(1)°, = 90.78(1)°, = 84.70(1)° and Z = 2. The moiety of an iron atom of [Fe(Himap)₂]BPh₄ was a pseudo octahedron with an FeN₄O₂ geometry. [Fe(R-Himap)₂]X was in high-spin state (about 5.9 B.M. at 80 K in solid state), and [Fe(R-Himat)₂]X was in low-spin state (about 2.0 B.M. at 293 K). The complex [Fe(Himsa)₂]ClO₄ with "5-6 member rings" and the deprotonated complex [Fe(Ph-Himap)(Ph-imap)] were in the high-spin state (6.0 B.M. at 80 K). It is concluded that the ligand field strength of an N₄S₂ donor set is stronger than that of an N₄O₂ donor set.