Design and Testing of a Robotic System for mr Image-guided Interventions

The effective integration of robotics together with magnetic resonance (mr) technology is expected to facilitate the real-time guidance of various diagnostic and therapeutic interventions. Specially designed robotic manipulators are required for this purpose, the development of which is a challenging task given the strong magnetic fields and the space limitations that characterize the mr scanning environment. A prototype mr-compatible manipulator is presented, designed to operate inside cylindrical mr scanners. It was developed for the study of minimally invasive diagnostic and therapeutic interventions in the abdominal and thoracic area with real-time mr image guidance. Initial tests were performed inside a high-field clinical mr scanner and included mr-compatibility tests and phantom studies on image-guided targeting.     

Storage of hydrogen in nanostructured carbon materials

Recent developments focusing on novel hydrogen storage media have helped to benchmark nanostructured carbon materials as one of the ongoing strategic research areas in science and technology. In particular, certain microporous carbon powders, carbon nanomaterials, and specifically carbon nanotubes stand to deliver unparalleled performance as the next generation of base materials for storing hydrogen. Accordingly, the main goal of this report is to overview the challenges, distinguishing traits, and apparent contradictions of carbon-based hydrogen storage technologies and to emphasize recently developed nanostructured carbon materials that show potential to store hydrogen by physisorption and/or chemisorption mechanisms. Specifically touched upon are newer material preparation methods as well as experimental and theoretical attempts to elucidate, improve or predict hydrogen storage capacities, sorption–desorption kinetics, microscopic uptake mechanisms and temperature–pressure–loading interrelations in nanostructured carbons, particularly microporous powders and carbon nanotubes.     

Microstructure effects in braze joints formed between Ag/W electrical contacts and Sn-coated Cu using Cu–Ag–P filler metal

Braze joints have been formed between Ag/W electrical contact tips and Sn-coated Cu straps using a Cu–Ag–P-based filler metal by short-cycle direct conductive heating from the Cu strap side. The microstructures of the braze joints have been investigated using a combination of scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron backscatter diffraction, focused ion beam milling, and transmission electron microscopy. The braze joints exhibit regions with two distinct types of microstructures. Type I microstructures contain three micro-constituents: FCC (Ag), FCC (Cu), and a ternary eutectic [(Ag) + (Cu) + Cu₃P]. The difference between the proportions of these phases and those in the baseline filler metal can be accounted for on the basis of P loss due to self-fluxing during the brazing process. Type II microstructures contain mostly (Ag) and (Cu) with a small amount of Cu₃P but no ternary eutectic mixture. Other differences from the Type I regions include a lower P content, incomplete dispersion of the Sn layer, and a refined grain size in the majority (Cu) phase. These effects are accounted for on the basis of local differences in interfacial pressure due to the geometry of the Ag/W contact surface.     

Catalytic combustion of carbon tetrachloride

The catalytic combustion of carbon tetrachloride (CCl4) by metal oxide catalysts coated on the monolith support was investigated. The prepared catalysts were tested at temperatures between 300 and 800 degrees C and at varying gas hourly space velocity (GHSV) values with an excess air ratio of 3100%. The catalyst, whose composition was 18% Cr2O3, 2% Ce2O3 and 80% gamma-Al2O3, was found to almost completely oxidize CCl4. The operating conditions proposed are 5702 h(-1) for GHSV, 3100% excess air and a temperature slightly higher than 800 degrees C. The reaction rate expression was found to be independent of oxygen partial pressure but strongly dependent on CCl4 partial pressure.     

Electrical and tribological properties of a Ni–18%Ru alloy for contact applications

A study of the microstructure, development of contact resistance during oxidation, and abrasive wear behavior for a Ni–18 at.%Ru alloy is presented in this article. It is shown that the alloy can be solutionized and aged, resulting in a fine lamellar mixture of FCC α-Ni and HCP β-Ru phases. Upon oxidation in air for 400 h, the measured contact resistance of the alloy is two orders of magnitude lower than that of pure Ni after 400-h oxidation. This behavior results from the formation of a low-resistivity rutile RuO₂ scale on the β phase lamellae, which gives conducting pathways through the insulating NiO scale that forms on the α phase. After an initial run-in period, the steady-state abrasive wear rate measured for the Ni–Ru alloy is an order of magnitude less than that of pure Ni. Since the micro-cutting and flaking wear mechanisms are the same, the differences in the wear rates are ascribed to the presence of the well-dispersed hard Ru-rich β phase. The combination of a low-resistivity self-healing native oxide scale and good wear properties makes the alloy an excellent candidate for electrical contact applications.     

Representing clinical narratives using conceptual graphs

The analysis of medical narratives and the generation of natural language expressions are strongly dependent on the existence of an adequate representation language. Such a language has to be expressive enough in order to handle the complexity of human reasoning in the domain. Sowa's Conceptual Graphs (CG) are an answer, and this paper presents a multilingual implementation, using French, English and German. Current developments demonstrate the feasibility of an approach to natural Language Understanding where semantic aspects are dominant, in contrast to syntax driven methods. The basic idea is to aggregate blocks of words according to semantic compatibility rules, following a method called Proximity Processing. The CG representation is gradually built, starting from single words in a semantic lexicon, to finally give a complete representation of the sentence under the form of a single CG. The process is dependent on specific rules of the medical domain, and for this reason is largely controlled by the declarative knowledge of the medical Linguistic Knowledge Base.     

Effective diffusion constant and adsorption constant of synthesized alumina,zirconia, and alumina–zirconia composite material

In this study, Al₂O₃, ZrO₂, and Al₂O₃–ZrO₂ composite materials were prepared with the sol–gel technique. X-ray diffraction analysis, differential scanning calorimetry–thermogravimetry, scanning electron microscopy–energy-dispersive X-ray spectrometry, nitrogen adsorption isotherm measurements, and helium pycnometry were used to characterize the resultant materials. Effective diffusion coefficients of helium and hydrogen and the adsorption equilibrium constant of hydrogen in the resultant materials were determined using single-pellet moment technique. The effective diffusivities of helium and hydrogen in both ZrO₂ and Al₂O₃–ZrO₂ composite pellets were found to be smaller than the value found for Al₂O_3, due to the lower tortuosity factor values of the Al₂O₃ pellet. It was found that hydrogen was weakly adsorbed on all resultant materials.     

Pretreatment of Afyon alcaloide factory's wastewater by wet air oxidation (WAO)

In this study, pretreatment of Afyon (Turkey) alcaloide factory wastewater, a typical high strength industrial wastewater (chemical oxygen demand (COD)=26.65 kgm(-3), biological oxygen demand (BOD(5))=3.95 kgm(-3)), was carried out by wet air oxidation process. The process was performed in a 0.75 litre specially designed bubble reactor. Experiments were conducted to see the advantages of one-stage and two-stage oxidation and the effects of pressure, pH, temperature, catalyst type, catalyst loading and air or oxygen as gas source on the oxidation of the wastewater. In addition, BOD(5)/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of a high-strength industrial wastewater, were determined at the end of some runs. After a 2h oxidation (T=150 degrees C, P=0.65 MPa, airflowrate=1.57 x 10(-5)m(3)s(-1), pH=7.0), the BOD(5)/COD ratio was increased from 0.15 to above 0.5 by using the salts of metals such as Co(2+),Fe(2+),Fe(2+)+Ni(2+),Cu(2+)+Mn(2+) as catalyst.