Ramsey-type spectroscopy with high-order harmonics

We present an experiment where Ramsey-type spectroscopy is applied to autoionizing states of krypton by using the ninth harmonic (88 nm) of a femtosecond Ti:sapphire laser. The ionization process, detected by an electron-energy spectrometer, shows the characteristic quantum interference pattern. The behavior of the fringe contrast compares favorably with a simple essential-state model, whose parameters have been taken from the literature. The experiment shows the feasibility of high-resolution spectroscopy in the extreme ultraviolet by using high-order laser harmonics.     

Cr:LiSrAlF6 channel waveguides as broadband fluorescence sources

We report on the production and fluorescence of active channel waveguides in Cr:LiSrAlF₆. We have produced ∼10 μm wide and 5 μm high channel waveguides by He⁺ ion implantation, lithographic patterning and subsequent Ar⁺ ion sputtering. Diode-pumped waveguides emitted 13 μW of fluorescence light with a spectrum ranging from 760 nm to 900 nm at a pump power of 165 mW and a pump wavelength of 660 nm. The compact and cheap optical pump source is a main advantage of this fluorescence material. This makes Cr:LiSrAlF₆ channel waveguides a suitable candidate for a broadband fluorescence source in low-coherence interferometry and other applications in the near-infrared wavelength range. PACS 42.70.Hj; 42.79.Gn; 42.30.Wb     

Cobalt ferrite nanoparticles: The control of the particle size and surface state and their effects on magnetic properties

In order to improve the efficacy of magnetic fluid hyperthermia (MFH) mediators, we synthesised cobalt ferrite nanoparticles with different sizes (between 5 and 7 nm) via successive polyol synthesis. The static and dynamic magnetic properties of the prepared particles, dispersed in a solid matrix, were investigated in order to evaluate the possibility of applying cobalt ferrite as magnetic susceptors in MFH. The effect on magnetic properties coming from the surface anchoring of the model molecule cetyl phosphate, was also investigated.     

Electrochemical stability of steel,Ti, and Cu current collectors in water-in-salt electrolyte for green batteries and supercapacitors

Journal of Solid State Electrochemistry - The electrochemical behaviour of steel, copper, and titanium current collectors was studied in aqueous solutions of lithium...     

Within-Plant Variation in Rosmarinus officinalis L. Terpenes and Phenols and Their Antimicrobial Activity against the Rosemary Phytopathogens Alternaria alternata and Pseudomonas viridiflava

This study investigated within-plant variability of the main bioactive compounds in rosemary (Rosmarinus officinalis L.). Volatile terpenes, including the enantiomeric distribution of monoterpenes, and phenols were analyzed in young and mature foliar, cortical and xylem tissues. In addition, antimicrobial activity of rosmarinic acid and selected terpenes was evaluated against two rosemary pathogens, Alternaria alternata and Pseudomonas viridiflava. Data showed that total concentration and relative contents of terpenes changed in relation to tissue source and age. Their highest total concentration was observed in the young leaves, followed by mature leaves, cortical and xylem tissues. Rosmarinic acid and carnosic acid contents did not show significant differences between leaf tissues of different ages, while young and mature samples showed variations in the content of four flavonoids. These results are useful for a more targeted harvesting of rosemary plants, in order to produce high-quality essential oils and phenolic extracts. Microbial tests showed that several terpenes and rosmarinic acid significantly inhibited the growth of typical rosemary pathogens. Overall, results on antimicrobial activity suggest the potential application of these natural compounds as biochemical markers in breeding programs aimed to select new chemotypes less susceptible to pathogen attacks, and as eco-friendly chemical alternatives to synthetic pesticides.     

Flavonoids in Lemon and Grapefruit IntegroPectin**

Following the analysis of terpenes present in new lemon and grapefruit “IntegroPectin” pectins obtained via the hydrodynamic cavitation of industrial lemon and grapefruit processing waste, the HPLC-MS analysis of flavonoid and other phenolic compounds reveals the presence of eriocitrin, naringin, hesperidin and kaempferol typical of the respective citrus fruits. The pectic fibers rich in rhamnogalacturonan-I regions act as chemical sponges adsorbing and concentrating at their outer surface highly bioactive citrus flavonoids and terpenes. These findings, together with the unique molecular structure of these new whole citrus pectins, provide preliminary insight into the broad-scope biological activity of these new biomaterials. Numerous new biomedical applications are anticipated, including likely use in the prevention and treatment of microbial infections and neurodegenerative disease.     

A new kinematic model for the closure equations of the generalized Stewart platform mechanism

The paper deals with the direct position analysis of the six degrees of freedom parallel manipulator known as generalized Stewart Platform Mechanism. When a set of actuator displacements is given the mechanism becomes a statically determined structure and the analysis solves for the closure of the structure. The governing equations are non-linear and many solutions are possible. Kinematic models reported in the literature relate to systems of six equations in six unknowns, which are solved numerically because of their complexity. Based on a novel approach, a new kinematic model of the structure is presented in this paper. It leads to a system of three equations in three unknowns that greatly reduces the computational burden. Finally, a case study has been reported.Paper presented at 2nd Int. Workshop on Advanced Robot Kinematics, Linz, Austria, 10–12 September, 1990.     

A Stimuli‐Responsive Rotaxane–Gold Catalyst: Regulation of Activity and Diastereoselectivity

A rotaxane‐based Au catalyst was developed and the effect of the mechanical bond on its behavior was studied. Unlike the non‐interlocked thread, the rotaxane requires a catalytically innocent cofactor, the identity of which significantly influences both the yield and diastereoselectivity of the reaction. Under optimized conditions, Au^I (the catalyst), Ag^I (to abstract the Cl^? ligand), and Cu^I (the cofactor) combine to produce a catalyst with excellent activity and selectivity.     

Transformations of benzothiadiphosphole system: General one‐pot synthesis of 1,2,5‐dithiaphosphepines and their precursor phosphanethiols

Treatment, at room temperature, of benzothiadiphosphole 1 with BrMg(CH₂)₅MgBr gives intermediate A , which was allowed to stand for about 3 h at room temperature. The subsequent addition of RMgX to the reaction mixture and the final treatment with an excess of S₈ and water affords the dithiaphosphepine sulfide 8 in good yields. The structure of this new heterocyclic system, containing both an S S unit and a PS group, is confirmed by an single crystal X‐ray structure determination. If the reaction is carried out without final treatment with sulfur we obtain, using PhMgBr as mono‐Grignard reagent, the corresponding ring‐opened product 11b , which can be easily transformed into the corresponding ring‐opened sulfide 12b by simple treatment with elemental sulfur. Further addition of sulfur to 12b gives quantitatively the cyclic dithiaphosphepine sulfide 8b . The two phosphanethiols 11b and 12b are of considerable interest. In fact, recently, attention has increasingly been paid to the coordination chemistry of polydentate ligands incorporating both thiolate and tertiary phosphine groups, also known as S P S pincer ligands. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:339–345, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20099     

On the Dynamics of the Carbon–Bromine Bond Dissociation in the 1-Bromo-2-Methylnaphthalene Radical Anion

This paper studies the mechanism of electrochemically induced carbon–bromine dissociation in 1-Br-2-methylnaphalene in the reduction regime. In particular, the bond dissociation of the relevant radical anion is disassembled at a molecular level, exploiting quantum mechanical calculations including steady-state, equilibrium and dissociation dynamics via dynamic reaction coordinate (DRC) calculations. DRC is a molecular-dynamic-based calculation relying on an ab initio potential surface. This is to achieve a detailed picture of the dissociation process in an elementary molecular detail. From a thermodynamic point of view, all the reaction paths examined are energetically feasible. The obtained results suggest that the carbon halogen bond dissociates following the first electron uptake follow a stepwise mechanism. Indeed, the formation of the bromide anion and an organic radical occurs. The latter reacts to form a binaphthalene intrinsically chiral dimer. This paper is respectfully dedicated to Professors Anny Jutand and Christian Amatore for their outstanding contribution in the field of electrochemical catalysis and electrosynthesis.