Thermal and Electrical Conductivity of Amorphous and Graphitized Carbide‐Derived Carbon Monoliths

The influence of graphitization and composition of carbide‐derived carbon (CDC) monoliths on the electrical and thermal conductivity was investigated. Carbon monoliths with varying porosities were synthesized employing biomorphous macroporous TiC and SiC as precursors. Graphitization was carried out in situ during high‐temperature chlorination with and without addition of nickel, iron, and cobalt chloride to the carbide. The graphitized monoliths showed improved properties. The results demonstrate that despite graphitic carbon also glass‐like carbon, stemming from the carbide synthesis, increases the thermal and electrical conductivity significantly.     

Histology and histochemistry of intervertebral discs of rats participated in spaceflight

The qualitative and quantitative histological and histochemical changes in the structure and macromolecular composition of lumbar intervertebral discs of rat during a 12.5-day space flight (Cosmos 1887 biosatellite) were determined using light and polarization microscopy. Semiquantitative histochemical, topo-optical reactions were measured and evaluated by retardation values of birefringence. (a) Lateral expansion and accumulation of the notochordal cells in the nucleus pulposus was observed in contrast with the vivarium control, where the chondroid cells dominated. (b) The cartilage and plate showed a swelling, which consisted mainly of hypertrophied cells sometimes with mild extracellular mineralization. (c) In the external zone of annulus fibrosus and cartilage end plate a mild decrease of orientation of collagen fibers was found. (d) A significant increase of orientation of hyase sensible glycosaminoglycans in the internal zone of annulus fibrosus and nucleus pulposus was observed. (e) In the external and internal zones of annulus fibrosus an increase of orientation of glycoproteids was revealed. The alterations of macromolecular components of intervertebral discs, cartilage end plates, and the osteoporotic changes of the lumbar vertebral bodies producing the looser structure of vertebral column after 12.5 day space flight suggest the necessity of the common evaluation of these structures, and may explain the heavy spinal pains of astronauts.     

Determining the relative effectiveness of islanding detectionmethods using phase criteria and nondetection zones

Islanding of a utility-interactive photovoltaic (UIPV) system occurs if the UIPV system continues to power a section of the utility system after that section has been disconnected from the utility source. Since islanding creates hazards for personnel and equipment, UIPV systems are required to detect and prevent it. It is desirable to have a simplified method of determining which islanding detection methods (IDMs) are most effective. In this paper, a previously described method for finding the nondetection zones (NDZs) of IDMs is experimentally verified. This method is used to determine the NDZs of several common IDMs. These results indicate that, of the IDMs discussed in this paper: (1) Sandia Frequency Shift (SFS) is most effective; and (2) the worst-case loads are low-power loads that are near resonance at the line frequency and have a large capacitance and small inductance (a high value of the quality factor Q)     

Novel properties of a 0.1-μm-long split-gate MODFET

A MODFET with two 30-nm-long gates (separated by 40 nm) has been fabricated using ultrahigh-resolution electron-beam lithography. The proximity of the two gate fingers along with the ability to independently bias them results in the following features: (a) tunability of the threshold voltage, (b) enhancement of the transconductance, especially at low current levels, (c) reduction in short-channel effects, and (d) high-voltage gain and cutoff frequency