Raman spectrum of a single crystal of 1,2,4,5-tetrachlorobenzene. Calculation of lattice vibrations.

Polarized Raman spectra of a single crystal of 1,2,4,5-C₆H₂Cl₄ at room temperature (β phase) in the lattice mode region have been obtained. The assignment of the bands to their proper factor group species allows a comparison with frequencies calculated using the atom-atom model. The agreement is good, supporting the transferability of the potential parameters. The lattice vibrations of the low-temperature α phase have also been obtained. The appearance of only five bands favours P₁ as the correct space group for this phase.     

Homozygous mutation of focal adhesion kinase in embryonic stem cell derived neurons: normal electrophysiological and morphological properties in vitro

Background  

Genetically manipulated embryonic stem (ES) cell derived neurons (ESNs) provide a powerful system with which to study the consequences of gene manipulation in mature, synaptically connected neurons in vitro. Here we report a study of focal adhesion kinase (FAK), which has been implicated in synapse formation and regulation of ion channels, using the ESN system to circumvent the embryonic lethality of homozygous FAK mutant mice.     

Passive harmonic mode-locked soliton fiber laser stabilized by an optically pumped saturable Bragg reflector

Stabilization of passive harmonic mode locking is achieved for what is believed to be the first time in an Er-Yb soliton fiber laser by optical pumping of the semiconductor saturable absorber above the bandgap. The results show 35-dB mode suppression of undesired harmonics.     

Total reflection X-ray fluorescence polymer spectra: classification by taxonomy statistic tools

The aim of this work is to explore the use of chemometric tools for the classification of synthetic and natural polymers with a mean molecular weight greater than 10(6). Total Reflection X-Ray Fluorescence (TXRF) spectra were obtained and analyzed in order to retrieve matrix information and to illustrate the calibration procedure. The intensities of the coherent and incoherent scattered peaks were specially selected for this purpose. The polymers studied were aqueous solutions of scleroglucan, polyacrilamide, polyoxyethylene oxide, glucomannan, 2,3,6-tri-o-ethylamylose and xhantan, in concentrations upto 1% (m/m). matlab software was used for numerical calculations. Using a combination of principal component analysis and cluster analysis, the differences in composition of various analyzed polymers can be visualized.     

Vibrational spectra,packing calculations and crystal structure of 1,2-diiodobenzene

The vibrational spectra of crystalline 1,2-diiodobenzene are presented. Spectroscopic evidence in combination with packing and lattice frequence calculations point to a tetramolecular unit cell, space group C⁵_2h- Approximate molecular positions are given.