Vaccination coverage in French 17-year-old young adults: an assessment of mandatory and recommended vaccination statuses.

We aimed to assess vaccination coverage (VC) in 17-year-old French young adults (YAs) participating in one mandatory Day of Defence and Citizenship (DDC). Between June 2010 and May 2011, YAs participating in 43 randomly selected mandatory sessions of the DDC programme in Poitou-Charentes (France) were asked to provide their personal vaccination record. Tetanus, diphtheria, polio, hepatitis B, Haemophilus influenzae b, pertussis, measles, mumps and rubella vaccination status were assessed at ages 2, 6, 13 and 17 years. Of 2610 participants, 2111 (81%) supplied documents for evaluation. Of these, 1838 (87%, M:F sex ratio 0·96) were aged 17 years (9% of the global population of this age in the area). The assessment of the 17-year-olds demonstrated the following rates of complete vaccination: diphtheria-tetanus-polio 83%; measles, mumps and rubella 83%; pertussis 69%; H. influenzae b 61%; human papillomavirus 47%; and hepatitis B 40%. At age 6 years, only 46% had received two doses of the vaccine against measles. The YAs were not aware of their status but were in favour of vaccination. VC in YAs is insufficient, particularly for hepatitis B, pertussis and measles. Combined vaccines and the simplification of vaccination schedules should improve VC. Preventive messages should focus on YAs.

Laser fragmentation in liquid medium: a new way for the synthesis of PbTe nanoparticles.

Synthesis of PbTe nanoparticles has been performed by pulsed laser fragmentation of PbTe micron-sized powders in distilled water with a Nd:YAG laser. The influence of various experimental parameters (wavelength, treatment duration, and output energy) on the yield of fragmentation, the size and the crystallographic structure of the nanoparticles produced has been investigated. Characterization of the nanopowders was performed by X-ray diffraction analyses and transmission electron microscopy observations. Thanks to a careful control of the synthesis parameters, PbTe nanoparticles with an average diameter close to 6 nm and exhibiting a sharp distribution in size have been produced.

High temperature thermoelectric properties of Mo3Sb(7-x)Te(x) (0.0≤x≤1.8).

Polycrystalline Mo(3)Sb(7-x)Te(x) samples with nominal Te concentrations of x=0.0, 0.3, 1.0, 1.6 and 2.2 have been synthesized by a powder metallurgical route. High temperature thermoelectric properties measurements including thermopower (300-900 K), electrical resistivity (300-800 K) and thermal conductivity (300-1000 K) were carried out. The temperature and compositional variations of the thermopower can be satisfactorily explained by assuming a single parabolic band model with dominant acoustic phonon scattering. However, such a simple model fails to describe the electronic thermal conductivity for low Te concentration. The dimensionless figure of merit, ZT, increases on increasing both the temperature and the Te content to reach a maximum value of 0.3 at 800 K that can be extrapolated to ∼0.6 at 1000 K for Mo(3)Sb(5.4)Te(1.6).

Crystal structure and transport properties of Ba8Ge43square3.

The single phase clathrate-I Ba(8)Ge(43)square(3) (space group Ia3d (no. 230), a = 21.307(1) A) was synthesized by quenching the melt between cold steel plates. Specimens for physical property measurements were characterized by microstructure analysis and X-ray diffraction on polycrystalline samples as well as single crystals. Transport properties including thermopower, electrical resistivity, thermal conductivity and specific heat were investigated in a temperature range of 2-673 K. The electrical resistivity exhibits a metal-like temperature dependence below 300 K turning into a semiconductor-like behaviour above 300 K. The analysis of the specific heat at low temperature indicates a finite density of states at the Fermi level, thus corroborating the metallic character below 300 K. The temperature dependence of the specific heat was modelled assuming Einstein-like localized vibrations of Ba atoms inside the cages of the Ge framework. A conventional crystal-like behaviour of the thermal conductivity with a low lattice contribution (kappa(l)(300 K) = 2.7 W m(-1) K(-1)) has been evidenced.