Synthesis of novel MMT/acyl-protected nucleo alanine monomers for the preparation of DNA/alanyl-PNA chimeras

Alanyl-peptide nucleic acid (alanyl-PNA)/DNA chimeras are oligomers envisaged to be beneficial in efficient DNA diagnostics based on an improved molecular beacon concept. A synthesis of alanyl-PNA/DNA chimera can be based on the solid phase assembly of the oligomer with mixed oligonucleotide/peptide backbone under DNA synthesis conditions, in which the nucleotides are introduced as phosphoramidites, whereas the nucleo amino acids make use of the acid labile monomethoxytrityl (MMT) group for temporary protection of the α-amino groups and acyl protecting groups for the exocyclic amino functions of the nucleobases. In this work, we realized for the first time the synthesis of all four MMT/acyl-protected nucleo alanines, achieved by deprotection/reprotection of the newly synthesized Boc/acyl intermediates, useful monomers for the obtainment of (alanyl-PNA)/DNA chimeras by conditions fully compatible with the standard phosphoramidite DNA synthesis strategy

Sulfur-Directed Olefin Oxidations: Observation of Divergent Reaction Mechanisms in the Palladium-Mediated Acetoxylation of Unsaturated Thioacetals

The Pd-mediated oxidation of unsaturated thioacetals gives either allyl or vinyl esters, depending on the substrate structure. We report the characterization of a range of sulfur-stabilized palladium intermediates via a combined computational and experimental NMR approach, demonstrating that the oxidation proceeds via two divergent reaction mechanisms. We were also able to synthesize an unusual sigma-bound Pd complex, via acetoxypalladation of an unsaturated dithiane, which was characterized by X-ray crystallography

Combined illumination sources for hyper-NA contact hole printing

Patterning of contact layers with minimal half pitch below 90nm has proven to be a very difficult task. in general, difficulties in contact patterning are driven by the low depth-of-focus (DoF) toward isolated contacts and/or the higher mask error enhancement factor (MEEF) for denser contact arrays. As for the illumination source shape, the traditional choice is between conventional illumination and off-axis illumination (OAI). Recent results obtained at IMEC on immersion scanners at 1.2 and 1.35 numerical aperture (NA), however, show that combined illumination sources, called Soft Annular and Soft QUASAR, are advantageous for through-pitch contact printing, in terms of MEEF and process latitude, without the use of assist features

French comparison exercise with the rotating neutron spectrometer, 'ROSPEC'

The French laboratories in charge of 'neutron' dosimetry using the spectrometer 'ROSPEC', formed a working group in 2001. The participants began to study the behaviour of the instrument with a comparison exercise in broad energy neutron fields recommended by the International Organisation for Standardisation (ISO) and available at the LMDN in Cadarache. The complete version of the ROSPEC is made up of six spherical proportional counters fixed to a rotating platform. These counters cover different energy ranges which overlap each other to provide a link between the detectors, within the energy range from thermal neutrons to 4.5 MeV. The irradiation configurations chosen were ISO standard sources (252Cf, (252Cf+D2 O)/Cd, 241Am-Be) and the SIGMA facility. The results show that the 'thermal and epithermal' neutron fluence was widely overestimated by the spectrometer in all configurations

Very preterm children free of disability or delay at age 2: predictors of schooling at age 8: a population-based longitudinal study.

International audienceAIM: To study the predictive value of a developmental assessment at 2 years corrected age (CA) for schooling at age 8 in children born very preterm and free of disability or delay; to identify other factors associated with schooling in this population. METHODS: 244 children born before 33 weeks in 1997, part of the population-based EPIPAGE cohort study, free of disability or delay, had their developmental quotient (DQ) evaluated with the Brunet-Lezine scale at 2 years CA. The mental processing composite (MPC) score was evaluated at age 5 with the K-ABC battery. Data on schooling were obtained at age 8 by postal questionnaire. Schooling was considered appropriate if the child was attending age-appropriate grade level in a regular classroom environment without support at school. RESULTS: Schooling was appropriate for 172 (70%) children. The predictive value of a DQ≥100 for appropriate schooling was 0.80 [0.75;0.85]. In children with a DQ at age 2<100, schooling varied significantly according to their MPC score at age 5 whereas it didn't in children with a DQ≥100. In multivariate analysis, the rate of appropriate schooling was significantly related to global DQ at age 2 (p<0.01), gestational age≥29 weeks (p<0.05), head circumference at age 2 (p<0.05) and mother's educational level (p<0.05). CONCLUSION: A DQ≥100 cannot be solely used for the prediction of appropriate schooling at age 8. Mother's educational level, gestational age and head circumference at age 2 could be taken account. These factors could be used to individualise follow-up

Early-onset or rapidly progressive scoliosis in children: Check the eyes!

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare autosomal recessive disorder characterized by the absence of conjugate horizontal eye movements, and progressive scoliosis developing in childhood and adolescence, caused by mutations in the ROBO3 gene which has an important role in axonal guidance and neuronal migration. We describe two female children aged 12 years and 18 months, with progressive scoliosis, in whom the neurological examination showed absent conjugate horizontal eye movements, but preserved vertical gaze and convergence. Cerebral Magnetic resonance imaging findings included pontine hypoplasia, absent facial colliculi, butterfly configuration of the medulla and a deep midline pontine cleft, while Diffusion tensor imaging (DTI) maps showed the absence of decussating ponto-cerebellar fibers and superior cerebellar peduncles. Somatosensory and motor evoked potential studies demonstrated ipsilateral sensory and motor responses. The diagnosis was confirmed by the identification of bi-allelic mutations in the ROBO3 gene