Richard Guggenheim

Influence of iron–silicon interaction on the growth of carbon nanotubes produced by chemical vapor deposition

Carbon nanotubes are often grown by chemical vapor deposition on silicon substrates covered with an iron catalyst. Photoemission and scanning electron microscopy studies presented here reveal how the iron silicide interface phase formed at elevated temperatures influences the catalytic efficiency of the iron. Moreover, we will show how the deposition of a thin layer of dense titanium nitride between the silicon substrate and the iron catalyst effectively prevents the formation of the silicide phase and consequently improves the carbon nanotubes growth.

Structural and optical properties of titanium aluminum nitride films (Ti1−xAlxN)

Titanium aluminum nitride films (Ti1−xAlxN) have been deposited by reactive magnetron cosputtering. Elemental compositions of these films have been determined by core level photoelectron spectroscopy. Scanning electron microscopy reveals a columnar film growth. This is also reflected by the topography of film surfaces as studied by atomic force microscopy. By x-ray diffraction a crystalline atomic structure is revealed. Single phase samples can be obtained, consisting of the substitutional solid solution (Ti, Al)N. Crystallites show preferential orientation. The optical properties of these films have been investigated by spectrophotometry in the UV-VIS-NIR wavelength range. Depending on the elemental composition, the optical constants vary from metallic to dielectric behavior. For film compositions with x<0.5 typical features are a tunable transmission maximum and reflection minimum in the visible spectral range, a high infrared reflection, and a low infrared absorption. Due to these optical properties, T...

HAARARTIGE HYPERKERATOSEN BEI EINEM NIERENTRANSPLANTIERTEN. EINE NEUE CYCLOSPORIN-NEBENWIRKUNG

ZusammenfassungWir berichten über einen 31jährigen nierentransplantierten Patienten, der unter Cyclosporin A eine ungewöhnliche Talgdrüsenhyperplasie entwickelte, begleitet von einer disseminierten, follikulär gebundenen, spikeartigen Hyperkeratose. Die Hautveränderungen waren besonders ausgeprägt im Gesicht und an den Streckseiten der Extremitäten. Stellenweise imponierte eine haarartige Hyperkeratose mit echter Haarneubildung. Die Histologie dieser Veränderungen zeigte eine stark vermehrte Keratinisation der Haarfollikel mit der Bildung von haarähnlichen „Spikes“, welche teilweise isoliert und in Verbindung mit echten Körperhaaren vorkamen. Aufgrund dieser Eigenschaft lassen sich differentialdiagnostisch die morphologisch sehr ähnliche „Disseminated Spiked Hyperkeratosis“ und andere filiforme Keratosen abgrenzen. Erstmals wird in der vorliegenden Arbeit dieser haarähnliche Aufbau auch mittels rasterelektronenmikroskopischer Aufnahmen dargestellt. Die Talgdrüsenfollikel zeigten eine z.T. zystische Ausweitung, wie sie bereits früher beschrieben worden ist, mit hier ebenfalls stark vermehrter Einlagerung von Keratinmassen. Dieser Fall zeigt, a) daß die beobachteten Hautveränderungen wahrscheinlich der alleinigen Wirkung von Cyclosporin A zuzuordnen und b), daß sie vermutlich dosisabhängig sind.SummaryWe report a 31-year-old renal transplant patient treated with cyclosporin A who developed an unusual sebaceous gland hyperplasia accompanied by a disseminated follicular spiny hyperkeratosis. Those alterations were most evident on his face and limbs. In some locations hairy hyperkeratosis with authentic hair neogenesis was found. The histology of these alterations showed a marked hyperkeratosis of the hair follicles with formation of hair-like spikes either alone or in connection with hairs. The presence of true hairs distinguishes our case from the morphologically similar disseminated spiked hyperkeratosis and other spiny keratinization disorders. Scanning electron microscopy helped to demonstrate the hair-like structure of these keratoses. Some of the sebaceous glands showed cystic widening of their lumina, which were filled with abundant amorphous eosinophilic material, a finding similar to earlier observations. Our case demonstrates that these skin alterations should be classified as side effects of cyclosporin A and that they are apparently dose-dependent.

Preparation and characterization of TiN–Ag nanocomposite films

Abstract Thin nanostructured films of TiN–Ag are deposited by a plasma vapour process consisting of co-sputtering of Ti and Ag from three magnetrons in an Ar–N 2 gas mixture. The coatings are characterized by in situ photoelectron spectroscopy, energy-filtered transmission electron microscopy and scanning electron microscopy. The dependence of the film structure and silver cluster distribution on total silver content, substrate biasing and substrate temperature was investigated.

A study of the microtriches and sensory processes of the tetrathyridium of Mesocestoides corti Hoeppli, 1925, by transmission and scanning electron microscopy

SummaryTwo types of microtriches occur on the tegument of the tetrathyridium of Mesocestoides corti as shown by scanning and transmission electron microscopy. One is filamentous and the other large and blade-like. The large form has a complex structure with a posteriorly directed support, so that its transverse section is T-shaped. The distribution of the two types on the body surface of the larva is not homogeneous. On the anterior part of the larva, including the suckers (Zone A), both are present. In the region behind the suckers (Zone B), only blade-like microtriches occur and on the posterior extremity (Zone C) only filamentous forms are seen. Between the Zones B and C there is an intermediate region with both types present. The authors suppose that the blade-like microtriches play an important role in tissue penetration, while the filamentous forms are involved in food uptake. Two types of sensory processes are identifiable. One is club-shaped, the other is a very long filamentous process.

Pili trianguli et canaliculi : a distinctive hair shaft defect leading to uncombable hair

Uncombable hair syndrome refers to a clinical disorder characterized by scalp hairs arranged in bundles in all directions that resist to brush and comb. Several entities may lead to spun-glass hair. As a rule the syndrome becomes obvious during the first years of life. The hair is normal in quantity, and increased fragility is not a common feature. The hair is often dry with silvery blond color. Under the light microscope the hairs may appear normal. Scanning electron microscopy shows a characteristic triangular, kidney- or heat-shaped diameter with typical longitudinal canalicular deformation. We present a 9-year-old girl with the typical clinical features of pili trianguli et canaliculi. Investigation by scanning electron microscopy confirmed the diagnosis. In addition the girl had enamel defects of the teeth and nail abnormalities that classify for a subtype of ectodermal dysplasia.

Early infection stages of the downy mildew fungi Sclerospora graminicola and Peronosclerospora sorghi in plants and cell cultures

The response of plants and callus cultures of resistant and susceptible cultivars of pearl millet and sorghum to inoculation with asexual spores of Sclerospora graminicola and Peronosclerospora sorghi was studied by light and scanning electron microscopy. Leaves of resistant cultivars were resistant to infection along the entire lamina whereas leaves of susceptible cultivars were susceptible only at the base. Callus cultures of resistant host cultivars were resistant and callus cultures of susceptible host cultivars were susceptible to infection. Direct germination of sporangia of S. graminicola is also reported.

Trichorhinophalangeal Syndrome Type III

Trichorhinophalangeal syndrome (TRPS) type III is a newly defined clinical entity. This symptom complex is inherited as an autosomal dominant trait and clinically characterized by growth retardation, craniofacial abnormalities, severe brachydactyly and sparse hair. In addition, absence of mental retardation and cartilaginous exostoses are required for the diagnosis of TRPS III. To further delineate this newly recognized entity, we report on a patient from a Turkish family segregating TRPS III in 7 family members. The patient had a very short stature (147 cm, < 3rd standard deviation), a thin upper lip and a prominent lower lip, a pear-shaped nose, stubby fingers and toes with cone-shaped epiphyses and sparse scalp hair. Scanning electron microscopy findings and results of energy-dispersive X-ray microanalysis are presented in such a patient for the first time.

Changing TiN film morphology by “plasma biasing”

The influence of the substrate potential with respect to the plasma on the morphology of reactively sputtered TiN thin films on Si(100) has been investigated. It is well known that the film quality with respect to grain size and distribution can be improved by applying a negative substrate bias to increase energetic ion bombardment. For large-area applications, however, a grounded substrate is very much desirable. Therefore, a technique has been developed to deposit films with comparably improved morphology on grounded substrates by means of a so-called “plasma electrode.” Grain size and distribution have been analyzed by top- and side-view scanning electron microscopy. To adjust the parameters for the TiN deposition we have used in situ photoelectron spectroscopy as the process control.

Influence of substrate bias voltage on surface morphology and nanocluster arrangement of gold containing amorphous hydrogenated carbon

Gold containing amorphous hydrogenated carbon (a-C:H/Au) thin films are studied by means of ex situ atomic-force and scanning electron microscopy, and in situ x-ray photoelectron spectroscopy. Introducing a dc substrate bias voltage during magnetron plasma-assisted chemical-vapor deposition of a-C:H/Au results in significant changes of surface morphology and nanocluster arrangement, compared to films deposited on electrically grounded substrates. Grounded samples are rather flat (below 1 nm of roughness), with topmost Au clusters covered with a very thin, nanometer-range layer of a-C:H. On the other hand, the biased sample surface is characterized by large bump structures (up to 13 nm in height) and bald gold clusters.