Ablation plasma ion implantation using a dc power supply

Experiments are reported in which ablation plasma ion implantation (APII) has been demonstrated using a dc power supply. The ability to use a dc power supply for APII has been accomplished by using a perpendicular orientation between the target and the substrate. This perpendicular orientation significantly reduces the arcing between the target and the substrate, in contrast to previous experiments using a parallel target–substrate orientation. With this new technique a KrF laser may be fired during the dc high voltage, accelerating full-energy ions. Initial experiments using dc APII have shown that Ti is deposited and implanted onto the Si substrate, with the highest concentration of Ti located beneath the surface of the film. The deposition/implantation of Ti ions onto Si was verified by X-ray photoelectron spectroscopy. PACS 52.38.Mf     

Analytical Hartree–Fock gradients with respect to the cell parameter: systems periodic in one and two dimensions

Analytical Hartree–Fock gradients with respect to the cell parameter have been implemented in the electronic structure code CRYSTAL, for the case of one- and two-dimensional periodicity. As in most molecular codes, Gaussian type orbitals are used to express the wavefunction. Examples demonstrate that the gradients have a good.     

The neutrino induced Doppler broadening technique and its application to the study of phonon creation in solids

Phonons in solids are studied experimentally by observing the motion of an atom which is at the origin of a lattice vibration. The atom is given an excess kinetic energy of 3 eV via the emission of an electron neutrino in a nuclear reaction. Its motion is observed by measuring the Doppler shift of subsequently emitted gamma-rays using ultra-high resolving power spectroscopy. In this way the motion of the atom during the first hundred of femtoseconds can be investigated. The results of the experiment are analysed using the Debye approximation and compared to a Molecular Dynamics simulation.     

Synthesis of Tenuilobine,a Bis-polyamine Alkaloid from Oncinotis tenuiloba,and Its Transamidation to Isotenuilobine

From the leaves of Oncinotis tenuiloba STAPF , a novel polyamine alkaloid, tenuilobine ( 9 ), was isolated. This paper presents the synthesis of 9 , as well as the base-catalyzed Zip reaction of 9 , leading to the transamidation product isotenuilobine ( 10 ). The structure of 10 was further confirmed by 2D-NMR correlation spectroscopy. For analytical purposes, the bis-polyamines 9 and 10 were converted into their pentaacetyl derivatives 12 and 11 , respectively, which were readily separable by reverse-phase HPLC.     

Mass spectrometric studies of potent inhibitors of farnesyl protein transferase--detection of pentameric noncovalent complexes

Farnesyl protein transferase (FPT) inhibition is an interesting and promising approach to noncytotoxic anticancer therapy. Research in this area has resulted in several orally active compounds that are in clinical trials. Electrospray ionization (ESI) time-of-flight mass spectrometry (TOF-MS) was used for the direct detection of a 95 182 Da pentameric noncovalent complex of alpha/beta subunits of FPT containing Zn, farnesyl pyrophosphate (FPP) and SCH 66336, a compound currently undergoing phase III clinical trials as an anticancer agent. It was noted that the desalting of protein samples was an important factor in the detection of the complex. This study demonstrated that the presence of FPP in the system was necessary for the detection of the FPT-inhibitor complex. No pentameric complex was detected in the spectrum when the experiment was carried out in the absence of the FPP. An indirect approach was also applied to confirm the noncovalent binding of SCH 66336 to FPT by the use of an off-line size exclusion chromatography followed by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) for the detection of the inhibitor.     

A constant entropy increase model for the selection of parallel tempering ensembles

The present paper explores a simple approach to the question of parallel tempering temperature selection. We argue that to optimize the performance of parallel tempering it is reasonable to require that the increase in entropy between successive temperatures be uniform over the entire ensemble. An estimate of the system's heat capacity, obtained either from experiment, a preliminary simulation, or a suitable physical model, thus provides a means for generating the desired tempering ensemble. Applications to the two-dimensional Ising problem indicate that the resulting method is effective, simple to implement, and robust with respect to its sensitivity to the quality of the underlying heat capacity model.     

Control of the LiFePO4 electrochemical properties using low-cost iron precursor in a melt process

Journal of Solid State Electrochemistry - LiFePO4 was prepared from low-cost iron ore concentrate (containing 4.48 wt.% SiO2 and MgO, CaO and Al2O3 below 0.5 wt.% as contaminant)...