Magnetic and optical properties of cobalt nanowires fabricated in polycarbonate ion-track templates

Cobalt nanowires with diameter 75 nm were synthesized in ion track-etched membranes by electrochemical deposition. Scanning electron microscopy displays cylindrical wires with smooth and homogeneous contours. X-ray diffraction studies indicate that the wires possess a face centered cubic structure and a preferred growth orientation along the [1 1 0] direction. The wires exhibit magnetic anisotropy, which is observed and is ascribed to shape anisotropy. The optical extinction spectrum shows a band which probably originates from a surface plasmon resonance.     

New concepts for lithium minerals processing

A new concept for the enrichment of lithium minerals is offering higher purity and higher yield by applying new processing technologies addressing the specific properties of the pegmatitic host rock. Additional value is created from high quality by-products which will improve the sustainability of mining activity and the overall cost base. Within the new concept, flotation may even be avoided where wet separation techniques are not applicable.Two innovative processing technologies have been integrated in the new concept: electrodynamic fragmentation and optical sorting. Detailed results of lab-technical tests show that the new process design can achieve highly selective liberation and separation processes. Optical and mineralogical analyses of the test products indicate a high benefit for commercial applications.     

Corrosion and permanent fracture resistance of coated and conventional orthodontic wires

The corrosion processes are presumed to have negative consequences on biocompatibility, aesthetic appearance and the frictional behavior between the bracket and the guiding arch during orthodontic treatment. A group of new guiding arches are the coated orthodontic wires. The present in-vitro study investigated the corrosion behavior and permanent fracture resistance of eight coated wires of different dimensions. Five superelastic nickel titanium (NiTi) wires (Titanol® Low Force River Finish Gold and Gold 2: Forestadent Corp.; Titanol® Superelastic tooth colored: Forestadent Corp.; Bioforce Sentalloy longuard: GAC Corp.; NiTi Imagination: GAC Corp.), two -titanium-wires (TMA Low Friction longuard: Ormco Corp.; TMA Low Friction longuard Purple: Ormco Corp.) and one steel wire (Stainless Steel Imagination: GAC Corp.) were selected. For comparison reasons three uncoated arch wires (Rematitan® Lite Dimple: Dentaurum Corp.; Titanol® Low Force River Finish: Forestadent Corp.; Bioforce Sentalloy: GAC Corp.) were included in the investigation. Surface modifications were made of teflon, polyethylene and by ion implantation. The corrosion processes have been carried out by the use of a specialized electrochemical cell. In a second experimental series the wires were exposed to mechanical stresses. Finally, all wires were examined in a scanning electron microscope. The results indicated that teflon coating prevented the corrosion of the wires. As expected, the -titanium wires did not corrode either. The other wires showed rupture potentials between 187 mV and 602 mV (NHE). After mechanical stress testing the wires could be subdivided into three groups. In the first group no differences could be recognized, the second group showed changes in their crystallographic structure and in the last group the teflon coating was peeled off from the surface of the wires.     

Relative resistance of striatal neurons containing calbindin or parvalbumin to quinolinic acid-mediated excitotoxicity compared to other striatal neuron types

To evaluate the relative ability of those striatal neuron types containing calbindin or parvalbumin to withstand a Ca(2+)-mediated excitotoxic insult, we injected the NMDA receptor-specific excitotoxin quinolinic acid (QA) into the striatum in mature adult rats and 2 months later examined the relative survival of striatal interneurons rich in parvalbumin and striatal projection neurons rich in calbindin. To provide standardization to the survival of striatal neuron types thought to be poor in Ca2+ buffering proteins, the survival was compared to that of somatostatin-neuropeptide Y (SS/NPY)-containing interneurons and enkephalinergic projection neurons, which are devoid of or relatively poorer in such proteins. The various neuron types were identified by immunohistochemical labeling for these type-specific markers and their relative survival was compared at each of a series of increasing distances from the injection center. In brief, we found that parvalbuminergic, calbindinergic, and enkephalinergic neurons all showed a generally comparable gradient of neuronal loss, except just outside the lesion center, where calbindin-rich neurons showed significantly enhanced survival. In contrast, striatal SS/NPY interneurons were more vulnerable to QA than any of these three other types. These observed patterns of survival following intrastriatal QA injection suggest that calbindin and parvalbumin content does not by itself determine the vulnerability of striatal neurons to QA-mediated excitotoxicity in mature adult rats. For example, parvalbuminergic striatal interneurons were not impervious to QA, while cholinergic striatal interneurons are highly resistant and SS/NPY+ striatal interneurons are highly vulnerable. Both cholinergic and SS/NPY+ interneurons are devoid of any known calcium buffering protein. Similarly, calbindin does not prevent striatal projection neuron vulnerability to QA excitotoxicity. Nonetheless, our data do suggest that calbindin may offer striatal neurons some protection against moderate excitotoxic insults, and this may explain the reportedly slightly greater vulnerability of striatal neurons that are poor in calbindin to ischemia and Huntington's disease.     

Abdominal trauma and pelvic injury in the growth period

Children with pelvic fractures usually are polytraumatized. Concomitant abdominal and pelvic injuries are not uncommon. Medical records and X-rays of 54 children, in which a pelvic fracture was diagnosed at our institution from 1974-1993, were reviewed. Children ages < or = 16 years and treated as in-patients were included in this study. The fractures were classified according to the AO-Classification. 47 patients (87.0%) had concomitant injuries. The mean Polytrauma Score was 23.7 (mean Injury Severity Score 30.5). Nine Children sustained an open pelvic fracture with rectal and/or vaginal tear. 15 genitourinary lesions were found in 13 children. 18 patients underwent laparotomy. A large pelvic/retroperitoneal hematoma was found in 11 cases. There were 7 liver lacerations, 7 splenic injuries, 2 mesenteric tears, 2 kidney injuries and 1 small bowel lesion. Eight children (14.8%) died with 5 of them due to retroperitoneal or/and abdominal bleeding complications. A recent follow-up examination (81.8%) with a mean follow-up of 11.3 years showed that long-term morbidity usually was attributed to pelvic concomitant injuries.     

Description of an experimental/theoretical method to determine the metal flow during steady-state forming processes

A new method to determine the metal flow within the deformation zone of stationary deformation processes is introduced. Specimen preparation and analysis are explained for hot rolling of bars and structural shapes. Theoretical fundamentals concerning material velocity in the deformation zone are defined and specific equations are deduced. The method is applied to bars and structural steel and its results are discussed, demonstrating possible problems, inaccuracies and limits.