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We report production of a self-injected, collimated (8 mrad divergence), 600 pC bunch of electrons with energies up to 350 MeV from a petawatt laser-driven plasma accelerator in a plasma of electron density ne = 1017 cm−3, an order of magnitude lower than previous self-injected laser-plasma accelerators. The energy of the focused drive laser pulse (150 J, 150 fs) was distributed over several hot spots. Simulations show that these hot spots remained independent over a 5 cm interaction length, and produced weakly nonlinear plasma wakes without bubble formation capable of accelerating pre-heated (~1 MeV) plasma electrons up to the observed energies. The required pre-heating is attributed tentatively to pre-pulse interactions with the plasma.
Phenotypical Down syndrome includes pharyngeal and maxillary hypoplasia and, frequently, constricted maxillary arch with nasal obstruction.
This clinical trial assessed the effects of rapid maxillary expansion on ENT disorders in 24 children with Down syndrome randomly allocated to receive either rapid maxillary expansion or not. Each group received ENT and speech therapy assessments before expansion and after the device had been removed.
In the rapid maxillary expansion group, the yearly ENT infection rate was reduced when assessed after device removal (p < 0.01). The parents of rapid maxillary expansion children reported a reduction in respiratory obstruction symptoms. Audiological assessment revealed improvements in the rapid maxillary expansion group (p < 0.01). Cephalometry showed increased maxillary width in the rapid maxillary expansion group.
Rapid maxillary expansion resulted in a reduction in hearing loss, yearly rate of ENT infections and parentally assessed symptoms of upper airway obstruction, compared with no treatment. These findings are probably related to expanded oronasal space, due to rapid maxillary expansion.
Inceptisols are the major forest soils in northern Taiwan. Some chemical, physical and morphological properties have been documented for these soils, yet there is little information on the mineralogy and the charge characteristics of their constituent 2:1 clay minerals. In this study we conducted a detailed characterization of the clay mineralogy of two Inceptisols. Two pedons were sampled at diagnostic horizons and the clay mineralogy was examined by X-ray diffraction. The magnitude of the layer charge of the 2:1 phyllosilicates was estimated using the alkylammonium exchange method (nC = 12). The clay mineralogy of both soils was dominated by vermiculite and mica with small amounts of kaolinite. The surface horizon contained more mica and kaolinite than the lower horizons. The mean layer charge of vermiculite ranged between 0.60 and 0.86 cmolc/(O10(OH)2). The distribution of clay layer charge decreased with increasing soil depth in two pedons. Differences in layer charge between samples are due to differences in weathering processes. The difference in the extent of clay mineral weathering in the A and Bsm horizons could be partly because the mineral surfaces in the Bsm horizon were coated with organo-Fe complexes which protected them from weathering.
The thermal and chemical stability of low k fluorinated amorphous carbon (a-C:F) material, deposited by a novel co-sputtering process using both polytetrafluoroethylene (PTFE) and graphite targets was investigated. Thin films of a-C:F with fluorine concentration of 2–55% were deposited, and carbon is observed by XPS in four distinct chemical states, C-C, C-F, C-F2, C-F 3. The relative intensity of C-Fx to C-C increased in intensity with increasing fluorine content and decreasing deposition temperature. Formation of tantalum fluoride was observed upon deposition of tantalum nitride, and the defluorination of the film could lead to reliability and delamination problems.
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