Silver: a novel growth catalyst for Ge nanoislands on Si(113)

The impact of silver pre‐adsorption on germanium growth on Si(113) was investigated using in‐situ low‐energy electron microscopy (LEEM) as well as low‐energy electron diffraction (LEED). The adsorption of silver leads to the formation of a regular pattern of nanofacets along the [1 0] direction. The periodicity of this pattern in [33 ] direction was determined to (44 ± 4) nm. From LEED series at different energies the facets were identified to be of (111) and (115) orientation. While the (111) facets show a (√3 × √3)‐R30° reconstruction, the (115) facets exhibit a (2 × n) superstructure. The subsequent growth of Ge results in the formation of nanoislands that are aligned along the facets. These Ge islands have an anisotropic shape with typical sizes of about 100 nm in [33 ] direction and 400 nm in [1 0] direction. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical study of three-dimensional magnetic photonic crystals opal/Fe3O4

Optical and magneto-optical properties of three-dimensional magnetic photonic crystals, based on magnetite Fe₃O₄ embedded into an opal film matrix, are investigated in both transmission and reflection. A strong enhancement of the polar Kerr effect and a modification of the Faraday effect have been found near the photonic band-gap of about 1.8 eV. Unusual changes of hysteresis curves and their dependence on photon energy have been revealed in the spectral region where the magneto-optical effect reverses its sign. This phenomenon has been explained by two types of magnetite particles inside the opal matrix having different coercive fields and spectral behaviour.     

15Nmethacetin test to control liver function of infants with formerly very low birth weight

Abstract

Hepatic detoxification capacities of three groups of infants aged about two were estimated using the [¹⁵N]methacetin elimination test, as well as standard serum parameters:

1. Formerly hypotrophically born infants still too small for their age (n = 23)

2. Patients suffering from severe liver diseases (n = 15)

3. Patients without liver diseases (n = 14).

17 of the infants of group 1 showed ¹⁵N elimination rates as low as the rates of the liver-diseased patients of group 2. Compared to the infants of group 3, who had normal values, the findings reflect diminished hepatic monooxygenases activities in groups 1 and 2. On the other hand, the serum parameters of the infants of group 1 did not deviate from normal values estimated in group 3. Here only group 2 showed pathological values. Consequently, the [¹⁵N]methacetin test seems to be more sensitive in controlling hepatic parameters of growth retardations than the usual serum parameters used here. Further investigations have to answer the question to which proportion intrauterine malnutrition and postnatal effects, such as environmental living conditions, contribute to the retardation of liver function development in combination with growth retardation.     

Study of semiconductor lasers under simultaneous uniaxial stress and hydrostatic pressure

Abstract

We present the design of a device for the simultaneous application of uniaxial stress and hydrostatic pressure. This new apparatus will for the first time allow measurements at constant strain. Results of the simultaneous application of uniaxial stress and hydrostatic pressure to a semiconductor laser are presented and discussed.     

Internal Biokinetic Behaviour of Molybdenum in Humans Studied with Stable Isotopes as Tracers

Abstract

Although molybdenum is considered to be an essential trace metal for humans, the knowledge about its metabolism is rather limited. The present study was aimed at the assessment of biokinetics following intravenous injection of trace amounts of ⁹⁵Mo or ⁹⁶Mo into five healthy volunteers. In a total of 11 investigations, the plasma clearance up to eight hours and the urinary excretion for at least three days after the injection were evaluated. The tracer concentrations were determined by proton nuclear activation analysis in blood plasma and by thermal ionization mass spectrometry in urine samples respectively. In all subjects, the plasma clearance is much faster than expected from the literature. The data obtained for the plasma clearance of the tracer can reasonably be fitted by a two exponential equation. The half times of the fast component range between 4 and 70 minutes and for the slow component between 3 and 30 hours. The urinary excretion of the injected tracer seems also to be faster than expected and the fractions lost are higher for larger doses administered. For the smallest dose given, 34% of the injected tracer were excreted within one day whereas for the four times larger dose about 60% were lost. These findings on urinary excretion are in agreement with recently published results.     

Drop deposition of thin nanostructured coatings of lead telluride

The current-voltage relationships of deposited structures are measured for cluster structures consisting of nanoparticles of lead telluride. Variation in the value of the tunnel current is shown. Optimum conditions for the possible emergence of quantum-hopping conductivity due to carrier tunneling (the characteristic sizes of the nanoclusters and the distances between them) are determined.     

7 T versus 3 T contrast-enhanced breast Magnetic Resonance Imaging of invasive ductulolobular carcinoma: First clinical experience

Purpose

Here we describe our first experience with contrast-enhanced (CE) MRI of breast cancer at 7 tesla (T), compared to 3 T and histopathology.

Materials and Methods

A 52 year old female patient with a mammographically suspicious breast mass (BI-RADS V) underwent 7 T CE-MRI. Results were described according to the BI-RADS-MRI criteria and compared to 3 T and histopathology.

Results

After contrast administration, a homogeneously enhancing, irregular spiculated mass was depicted at both 3 T and 7 T; sizes were identical. The most malignant kinetic curve was characterized by a rapid initial rise followed by a wash-out pattern in the delayed phase, i.e. a type 3 curve, at both field strengths. Even though T1-effects of contrast agents are suggested to be reduced at higher fields, quantification of contrast enhancement-to-noise ratio showed a ratio of 4.6 at 7 T and 2.8 at 3 T when comparing contrast-to-noise of the mass before and after contrast administration. Both examinations, using a single dose of gadolinium-based contrast agent, achieved good image quality. Final histopathological evaluation showed an invasive ductulolobular carcinoma with an intraductal component.

Conclusion

This initial experience suggests that clinical contrast-enhanced 7 T MRI of the breast is technically feasible and may allow BI-RADS-conform analysis.     

X-ray diffuse scattering measurements of nucleation dynamics at femtosecond resolution

Femtosecond time-resolved small and wide angle x-ray diffuse scattering techniques are applied to investigate the ultrafast nucleation processes that occur during the ablation process in semiconducting materials. Following intense optical excitation, a transient liquid state of high compressibility characterized by large-amplitude density fluctuations is observed and the buildup of these fluctuations is measured in real time. Small-angle scattering measurements reveal snapshots of the spontaneous nucleation of nanoscale voids within a metastable liquid and support theoretical predictions of the ablation process.     

FOURIER ANALYSIS OF TEMPORAL AND SPATIAL OSCILLATIONS OF TUNNELING CURRENT IN SCANNING TUNNELING MICROSCOPY

Partially oxidized Si(111) surfaces and surfaces of highly oriented pyrolytic graphite (HOPG) were studied by two different ultrahigh vacuum scanning tunneling microscope (UHV-STM) systems and by an STM system working under ambient conditions, respectively. The STM current images of partially oxidized Si(111) surfaces and HOPG surfaces were analyzed by one/two-dimensional fast Fourier transformation (1D-FFT/2D-FFT). The phenomenon of temporal oscillations of tunneling current on the partially oxidized Si(111) surfaces was detected with both UHV-STM systems. Temporal as well as spatial oscillations of tunneling current appeared in highly resolved STM current images of the Si(111) surfaces simultaneously, but both kinds of oscillations could be discriminated according to their different influence on the 2D-FFT spectra of the current images, while varying the scanning range and rate. On clean HOPG surfaces only spatial oscillations of tunneling current induced by the surface structure were observed.