A New Approach to Understand the Adsorption of Thiophene on Different Surfaces: An Atom Probe Investigation of Self-Assembled Monolayers.

Atom probe tomography was used to analyze self-assembled monolayers of thiophene on different surfaces, including tungsten, platinum, and aluminum, where the tungsten was examined in both pristine and oxidized forms. A glovebag with controlled atmospheres was used to alter the level of oxidation for tungsten. It was shown that different substrates lead to substantial changes in the way thiophene adsorbs on the surface. Furthermore, the oxidation of the surface strongly influenced the adsorption behavior of the thiophene molecules, leading to clear differences in the amounts and compositions of field evaporated ions and molecular ions.

A multi-ion plasma FIB study: Determining ion implantation depths of Xe, N, O and Ar in tungsten via atom probe tomography.

In this study atom probe tomography was used to determine the implantation depth of four different plasma FIB ion species - xenon, argon, nitrogen, and oxygen - implanted at different acceleration voltages. It was found that lowering the beam energy reduces the implantation depth, but significant implantation was still observed for N, O and Ar at beam energies as low as 2 kV. Furthermore, nitrides and oxides were observed that were formed when using N and O. Xe had the lowest implantation depth compared to Ar, N and O when using the same conditions. No Xe ions were detected in the sample prepared at 2 kV. Experimentally-determined implantation depths were compared to calculated implantation depths. The experiments exhibited deeper-than-predicted ion implantation into the microstructure, but lower-than-predicted ion concentrations.

Mid-facial anthropometry in second-trimester fetuses with trisomy 21: a three-dimensional ultrasound study.

OBJECTIVES: The aim of this study was to evaluate whether fetuses with trisomy 21 and detectable nasal bones have a distinct facial anthropometry that can be objectively defined using three-dimensional (3D) ultrasonography. METHODS: A prospective cross-sectional study of 40 fetuses in the second trimester, 17 with trisomy 21 and 23 controls, was performed. The 3D volume datasets of each case were evaluated for documentation of the nasal bones using the multiplanar and the maximum mode. The nasal bone length and the angle formed by the two maxillary bones at the level of the frontal process were then measured. RESULTS: The nasal bones were absent in 7 (41%) of the 17 fetuses with Down syndrome. All of the 23 normal fetuses had detectable nasal bones. The difference between nasal bone length in trisomy 21 fetuses and controls did not reach statistical significance (p = 0.087). The mean maxillary angle in trisomy 21 fetuses with nasal bones was significantly wider compared to controls (p = 0.029). CONCLUSIONS: The nasal bones are present in the majority of fetuses with trisomy 21 in the second trimester. This group of fetuses has a characteristic mid-facial anthropometry (wider maxillary angle) that can be assessed by means of 3D ultrasonography.

Three-dimensional ultrasonographic reslicing of the fetal brain to assist prenatal diagnosis of central nervous system anomalies.

OBJECTIVES: The purpose of this study was to evaluate the potential of 3-dimensional ultrasonographic planar and nonplanar reslicing techniques. METHODS: Fetuses with severe brain anomalies diagnosed by means of 2-dimensional ultrasonography were prospectively included in the study. Good-quality 3-dimensional volumes of the fetal head were obtained in each case. Subsequently, these volumes were reviewed with use of 3-dimensional extended imaging with Oblique View and DynamicMR (Medison Co, Ltd, Seoul, Korea). RESULTS: Eight fetuses (mean gestational age, 23 weeks; range, 20-30 weeks) with the following central nervous system anomalies were examined: semilobar holoprosencephaly, absent cavum septum pellucidum, porencephaly in twin-to-twin transfusion syndrome, partial agenesis of the corpus callosum, Dandy-Walker variant, open-lip schizencephaly, aneurysm of the vein of Galen, and dilated cavum vergae. CONCLUSIONS: Planar and nonplanar reslicing of the volumes delivered informative images in any reconstructed plane. One important prerequisite, however, was the absence of acoustic shadowing during data acquisition.