C-kit receptor in the human vas deferens: distinction of mast cells, interstitial cells and interepithelial cells

The molecular mechanisms underlying the regulation of vas deferens (VD) motility and semen emission are still poorly understood. Interstitial cells of Cajal (ICC), which harbour the c-kit receptor (CD117), provide the basis of coordinated gut motility. We investigated whether c-kit receptor-positive cells also exist in the normal human VD. Enzyme and fluorescence immunohistochemical techniques were applied on serial sections of human proximal, middle, and distal VD segments (n=49) employing 13 different monoclonal and polyclonal antibodies recognizing the c-kit receptor. The c-kit receptor was detected in either round- or spindle-shaped cells. On account of their antigenic profile, the round- and oval-shaped c-kit receptor-positive cells were identified as mast cells (MC) occurring in all layers of the VD except the epithelium. In contrast, two distinct populations of exclusively c-kit receptor-positive spindle-shaped cells were found within the lamina propria and, rarely, in the inner and outer smooth muscle layers, as well as within the epithelium. Different shaped c-kit receptor-positive MC and IC were present in all layers of the human VD. Our findings demonstrate the presence of different c-kit receptor-positive cells also in the human VD. Their rather ubiquitous distribution within the lamina propria and muscle layers suggests that IC and MC may modulate the neuromuscular transmission and the propagation of electrical signals in multiple systems involved in the draining of fluids. The importance of the c-kit receptor-positive interepithelial cells remains unclear.     

An atomic-scale study of hydrogenated silicon cluster deposition on a crystalline silicon surface

Controlled deposition of clusters on solid surfaces has attracted lots of attention in recent years, because of its potential application to tailoring the desired electronic properties of the resulting surfaces. We have carried out an atomic-scale study to understand the deposition mechanism. The molecular dynamics approach based on a modified Tersoff potential is used to simulate the deposition mechanism of hydrogenated silicon clusters on a crystalline silicon surface in detail. The important factors governing the deposition process such as impact energy and substrate temperature, are investigated for the hydrogenated silicon cluster Si₂₉H₂₄ on a H-terminated Si(100)-(2x1) surface.     

Intermittent-contact scanning capacitance microscopy versus contact mode SCM applied to 2D dopant profiling

This study compares two different methods of scanning capacitance microscopy (SCM). The first and approved one operates in contact mode and the second novel one in intermittent-contact (IC) mode. Measurements were performed on several samples and the results are compared. New technical expertises on the novel intermittent-contact method are shown and in conclusion assets and drawbacks of this SCM method are emphasized.     

Pressure drop measurements of ceramic sponges—Determining the hydraulic diameter

This paper presents experimental results of pressure drop measurements for different solid ceramic sponges. In the experiments, the material, pore sizes and porosity were varied. Furthermore, this data is correlated using an Ergun-type equation. It was possible to obtain Ergun constants for sponges independently of the varied parameters. In the future, the presented pressure drop correlation will provide a simple method for determining hydraulic diameters for solid ceramic sponges with unknown geometric parameters (strut, window and pore diameter,…) based on pressure drop measurements. Furthermore a correlation is given to derive the hydraulic diameter from the ppi (pores per inch) number.     

Zum Querkraftwiderstand bei Leichtbetonbalken ohne Querkraftbewehrung

In diesem Beitrag wird über Biegeschubversuche mit Leichtbetonbalken ohne Querkraftbewehrung berichtet, die ein ausgeprägtes Nachbruchverhalten aufwiesen. Die Versuchsergebnisse der Leichtbetonbalken werfen die Frage auf, ob die Querkraftbemessung in der neuen DIN 1045‐1 in der Lage ist, hoch spröde Betone wie ALWAC (All Lightweight Aggregate Concrete) hinreichend sicher zu erfassen. In diesem Zusammenhang wird näher auf den Maßstabseffekt eingegangen. Es wurde ein Modell für das Tragverhalten von Biegeschubbalken nach Auftreten des Biegeschubrisses entwickelt, das auf der Kinematik von miteinander verbundenen Festkörpern anstelle von Fachwerkstäben beruht. Ein Ansatz der Tragkapazität im Nachbruchbereich für die Praxis wird nicht empfohlen. Shear Strength of Lightweight Concrete without Shear Reinforcement This paper presents results of shear beam tests with lightweight concrete and without shear reinforcement exhibiting a distinct post peak behavior. The shear test results raise the question whether the shear design in DIN 1045‐1 can also cover very brittle concrete types as ALWAC (All Lightweight Aggregate Concrete) with a sufficient safety level. The size effect in shear beams is discussed. A model for the load bearing behavior after formation of the inclined crack based on the kinematics of a set of rigid bodies is developed. A consideration of the additional load capacity in the post peak range in design formulas is not recommended.     

Displacement current sensor for contact and intermittent contact scanning capacitance microscopy

In this study a displacement current capacitance sensor (DCCS) for scanning capacitance microscopy (SCM) is introduced. It can be used for both intermittent contact (IC) and contact-SCM operation. Based on I/V conversion and subsequent lock-in amplification a displacement current can be detected and used as a measure for dopant concentration. Therefore a periodic variation of the AFM tip substrate capacitance is required. This can be achieved either by a periodic tip oscillation (IC-SCM) or an applied AC voltage between tip and sample (contact-SCM). The advantage of the DCCS is the linearity, which makes it possible to detect absolute dopant concentrations.     

Vergleichende Lebenszykluskostenanalyse für Fußgängerbrücken aus unterschiedlichen Werkstoffen

Comparative life‐cycle cost analysis of pedestrian bridges made from different materials. Considerable maintenance costs may accrue during the life time of infrastructure objects. Therefore, the choice of construction options should not only be made based on purchase price, but also taking into account expected follow‐up costs. Against this background, a study conducted with Deutsche Bahn AG and Peter Maier Leichtbau GmbH analyzed which construction material promises the best overall cost‐effectiveness for pedestrian bridges. Cost‐effectiveness was evaluated based on a life‐cycle‐cost analysis. This study investigated pedestrian bridges built of conventional construction materials wood, steel and reinforced concrete, as well as bridges made of aluminium alloy. An annuity was chosen to be the comparison value for life‐cycle costs. For coping with uncertainties in cost determination and forecasting, diverse sensitivity analyses were used to verify their effects on the final results. Aluminium alloy came out to be the most cost‐effective option for the bridge system investigated within this study.     

A Janus cobalt-based catalytic material for electro-splitting of water

The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable and efficient systems for the conversion and storage of renewable energy sources. The production of hydrogen through water splitting seems a promising and appealing solution. We found that a robust nanoparticulate electrocatalytic material, H(2)-CoCat, can be electrochemically prepared from cobalt salts in a phosphate buffer. This material consists of metallic cobalt coated with a cobalt-oxo/hydroxo-phosphate layer in contact with the electrolyte and mediates H(2) evolution from neutral aqueous buffer at modest overpotentials. Remarkably, it can be converted on anodic equilibration into the previously described amorphous cobalt oxide film (O(2)-CoCat or CoPi) catalysing O(2) evolution. The switch between the two catalytic forms is fully reversible and corresponds to a local interconversion between two morphologies and compositions at the surface of the electrode. After deposition, the noble-metal-free coating thus functions as a robust, bifunctional and switchable catalyst.     

Design of an LED-based sensor system to distinguish human skin from workpieces in safety applications

Commercial light curtains use a technique known as muting to differentiate between work pieces and other objects (e.g., human limbs) based on precise model knowledge of the process. At manually fed machinery (e.g., bench saws), such precise models cannot be derived due to the way the machinery is used. This paper presents a multispectral scanning sensor to classify an object's surface material as a new approach for the problem. The system is meant to detect the presence of limbs and therefore optimized for human skin detection. Evaluation on a test set of skin and (wet) wood samples showed a sufficiently high reliability with respect to safety standards.