Optical properties of N+ ion-implanted and rapid thermally annealed Si(100) wafers studied by spectroscopic ellipsometry

The optical properties of N+ ion-implanted Si(100) wafers have been studied using the spectroscopic ellipsometry (SE). The N+ ions are implanted at 150 keV with fluences in the range between 1 ×10↑16 and 7.5×10↑16 cm−2 at room temperature. A Bruggeman effective-medium-approximation and a linear-regression analysis require a four-phase model (substrate/first and second damaged layers/ambient) to explain the experimental data of the as-implanted samples. These analyses suggest that the buried fully amorphous layer can be formed at around ～5×10↑16 cm−2 dose. The rapid thermal annealing is performed at 750°C in a dry N2 atmosphere on N+ ion-implanted samples. The SE data reveal that the recrystallization starts to occur very quickly. The time constant for the defect annealing in the deeper damaged layer is determined to be 36 s. The dielectric-function spectra ε(E) of microcrystalline silicon deduced here differ appreciably from that of the single-crystalline silicon, especially in the vicinity of the critical points

Causes and consequences of stress generation : Longitudinal associations of negative events, aggressive behaviors, rumination, and depressive symptoms

The present study examined the causes and consequences of stress generation in university students in Japan. A two-wave longitudinal study with an 8- or 9-week interval was conducted in the fall of 2020. Undergraduate and graduate students at four universities in Japan (N = 201) completed self-report measures assessing experiences of negative interpersonal dependent events, negative non-interpersonal events, and negative independent events at two times. At the same time, they also responded to measures of aggressive behaviors, trait rumination, and depressive symptoms. Path analyses revealed that baseline aggressive behaviors were positively associated with an increase in subsequent negative interpersonal dependent events, even after controlling for the influences of negative interpersonal dependent events, rumination, and depressive symptoms at baseline. However, aggressive behaviors were not significantly associated with subsequent negative non-interpersonal dependent events or negative independent events. These findings suggest that aggressive behaviors may have been a factor leading to interpersonal stress generation. Furthermore, all categories of negative event experiences predicted an increase in subsequent depressive symptoms, but not subsequent rumination, and rumination was not significantly associated with subsequent depressive symptoms. This research extends previous studies on the causes and consequences of stress generation conducted in the US by using specific measures of aggressive behaviors and including a non-restricted sample of university students in Japan

Capturing molecular structural dynamics by 100 ps time-resolved X-ray absorption spectroscopy

An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented

Reversible phase transition in laser-shocked 3Y-TZP ceramics observed via nanosecond time-resolved X-ray diffraction

The high-pressure phase stability of the metastable tetragonal zirconia is still under debate. The transition dynamics of shocked Y2O3 (3 mol%) stabilized tetragonal zirconia ceramics under laser-shock compression has been directly studied using nanosecond time-resolved X-ray diffraction. The martensitic phase transformation to the monoclinic phase, which is the stable phase for pure zirconia at ambient pressure and room temperature, has been observed during compression at 5 GPa within 20 ns without any intermediates. This monoclinic phase reverts back to the tetragonal phase during pressure release. The results imply that the stabilization effect due to addition of Y2O3 is negated by the shear stress under compression.Comment: 11 pages, 4 figures, draf

Evaluation of hemodynamic imaging findings of hypervascular hepatocellular carcinoma: comparison between dynamic contrast-enhanced magnetic resonance imaging using radial volumetric imaging breath-hold examination with k-space-weighted image contrast reconstruction and dynamic computed tomography during hepatic arteriography

To compare the visualization of hemodynamic imaging findings of hypervascular hepatocellular carcinoma (HCC) on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using radial volumetric imaging breath-hold examination with k-space-weighted image contrast reconstruction (r-VIBE-KWIC) versus dynamic computed tomography during hepatic arteriography (dyn-CTHA). We retrospectively reviewed the databases of preoperative DCE-MRI using r-VIBE-KWIC, dyn-CTHA, and postoperative pathology of resected specimens. Fourteen patients with 14 hypervascular HCCs underwent both DCE-MRI and dyn-CTHA. The imaging findings of the tumor and adjacent liver parenchyma were assessed on both modalities by two readers. The tumor enhancement time was also compared between the two modalities. On DCE-MRI/dyn-CTHA, early staining, peritumoral low-intensity or low-density bands, corona enhancement, and washout of HCC were observed in 14/14 (100%), 10/12 (83%), 11/14 (78%), and 4/14 (29%) patients, respectively. Pathologically, four HCCs with low-density bands on dyn-CTHA had no fibrous capsules. The median tumor enhancement time on DCE-MRI and dyn-CTHA was 24 (9-24) and 23 (8-35) s, respectively. The correlation coefficient between the two groups was 0.762 (P < 0.002). DCE-MRI using r-VIBE-KWIC has diagnostic potential comparable with that of dyn-CTHA in the hemodynamic evaluation of hypervascular HCC except for the washout phenomenon.ArticleJAPANESE JOURNAL OF RADIOLOGY.36(4):295-302(2018)journal articl