Yukawa model on a lattice: Two-body states

We present some Quantum Field Theory (QFT) results concerning the Yukawa model, solved non-perturbatively with the help of lattice techniques. In particular we focus on the possibility of generating a two-nucleon bound state, as compared to the non-relativistic limit of the same model. Preliminary results show the appearance of zero modes of the Dirac operator. They limit the numerical solution of the model to values of the coupling constant which are too small to allow binding of the two-nucleon system.     

Constraints on the IR behaviour of gluon and ghost propagator from Ward-Slavnov-Taylor identities

We consider the constraints of the Slavnov-Taylor identity of the IR behaviour of gluon and ghost propagators and their compatibility with solutions of the ghost Dyson-Schwinger equation and with the lattice picture.     

Qualitative electroless Ni/Au plating considerations for the solder mask on top of sequential build-up layers

Advanced printed circuit boards (PCBs) with sequential build-up (SBU) layers require alternating dielectric and copper layers on top of a core substrate. This can be achieved by lamination of resin coated copper (RCC) or by coating of dielectric polymers followed by copper deposition. The plating of electroless Ni/Au used as a solderability preservative on top of sequential build-up layers is investigated. For this application a solder mask polymer has to be applied in order to separate solder pads. Experiments showed that on parts of the underlying build-up layer exposed to the electroless Ni plating solution electroless Ni can grow. This overplating is caused by the remains of colloidal Pd/Sn catalyst on top of the build-up layer from preceding electroless Cu deposition. At very small features skipping of the plating can also take place. The overplating and skipping phenomena are influenced by a number of parameters, such as the temperature, the concentration of the stabilizer and pH. The dimensions of features on the board and the thickness of the solder-mask polymer also influence skipping. Based on qualitative analyses of the skipping and overplating phenomena rules of thumb for the solder mask design based on the plating conditions are proposed.     

An adaptive phase/Doppler system and its applications including particle sizing in submicron and nanometer ranges

Recent developments in the theory and applications of the phase Doppler technique are reviewed. It is now possible to recognize particle material and to measure size and velocity of (i) metallic particles as small as 20 nm, (ii) transparent particles in the submicron range, and (iii) particles with refractive index approaching the surrounding medium. These diverse applications are met with an adaptive hardware for the phase/Doppler velocimeter (PDV), which is more flexible than the conventional device. Also software tools are introduced that provide a rigorous procedure to lay out the optics for various new and old applications. The effectiveness of the new measuring system is demonstrated through several examples.     

Crystal and molecular structure of syndiotactic 2,4,6-triphenylheptane,a polystyrene model moleculE

The crystal and molecular structures of syndiotactic 2,4,6-triphenylheptane have been determined by direct methods and refined from X-ray diffraction data recorded with a four-circle diffractometer and Mo Kα radiation. The unit cell is monoclinic, space group P2₁/c; at room temperature, a = 16.831, b = 9.104, c = 34.390 Å and β = 128.11°. It is found that the two molecules in the asymmetric unit have the same trans conformation of the chain, with aromatic rings virtually perpendicular to the chain.     

A carbon-13 nuclear magnetic resonance study of compounds substituted by a perfluoroalkyl chain

The ¹³C NMR spectra of alkanes, alkanones and cyclohexanones substituted by perfluoroalkyl groups, R_F, have been studied. The influence of the perfluoroalkyl group on the chemical shifts of other carbons of the molecules is the same regardless of the R_F chain length.