Ion-counting nanodosemeter with particle tracking capabilities

An ion-counting nanodosemeter (ND) yielding the distribution of radiation-induced ions in a low-pressure gas within a millimetric, wall-less sensitive volume (SV) was equipped with a silicon microstrip telescope that tracks the primary particles, allowing correlation of nanodosimetric data with particle position relative to the SV. The performance of this tracking ND was tested with a broad 250 MeV proton beam at Loma Linda University Medical Center. The high-resolution tracking capability made it possible to map the ion registration efficiency distribution within the SV, for which only calculated data were available before. It was shown that tracking information combined with nanodosimetric data can map the ionisation pattern of track segments within 150 nm-equivalent long SVs with a longitudinal resolution of approximately 5 tissue-equivalent nanometers. Data acquired in this work were compared with results of Monte Carlo track structure simulations. The good agreement between 'tracking nanodosimetry' data acquired with the new system and simulated data supports the application of ion-counting nanodosimetry in experimental track-structure studies.     

A novel and simple approach for assessing the freshness of hazelnuts

Visual inspection and sensory analysis are the only suitable ways to assess the quality of hazelnuts under routine conditions. To obtain a more objective parameter for the freshness, a fast and easy-to-use method was developed. It is based on the well-known test for the germination capacity of seeds where their vitality is determined by use of 2,3,5-triphenyltetrazolium chloride (TTC) which is reduced by flavo enzymes to 1,3,5-triphenylformazane, which appears red. For the determination, 100 hazelnut halves were embedded in TTC containing methyl cellulose gel on a glass plate and kept at 35 °C in the dark. After 6 h, the cut planes of viable nuts were stained red, the cut planes of rotten nuts were yellow or brown, and the colour of dead or mould-infected nuts remained unchanged. The colour pattern was examined either visually by counting the coloured halves or with computer support using image editing software. The ratio of the sum of coloured areas to the total area of the hazelnut cut planes gave a measure of the average degree of viability ("vitality index"). The analysis of several samples of hazelnuts of well-defined age and storage conditions confirmed the efficiency of the method.     

Morphomechanics of the humero-ulnar joint: I. Joint space width and contact areas as a function of load and flexion angle

BACKGROUND: Previous studies have shown that the trochlear notch is deeper than necessary for an exact fit with the humerus. However, humero-ulnar joint space width and contact areas have so far not been quantified for variations in the load and angle of flexion. METHODS: Six fresh cadaveric specimens were investigated at 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion and at loads of 25 and 500 N, simulating resisted elbow extension. The joint space width and contact were determined, using polyether casting material. RESULTS: At 25 N all joints made contact in the ventral and dorsal aspects of the articular surfaces, whereas in the depth of the trochlear notch the joint space was on average between 0.3 and 2.8 mm wide, with some variation between individuals. At 500 N the joint space width was considerably reduced and the contract areas expanded towards the depth of the notch. The size of the dorsal contact areas was significantly smaller at 30 degrees and that of the ventral ones at 120 degrees, their ventro-dorsal ratio decreasing considerably from 30 degrees to 120 degrees (p < 0.01). CONCLUSION: These results indicate that the size of the contact areas depends to a slight extent on the joint position, but that at all loads and flexion angles a bicentric contact and an important central joint space width emerge because of the concave incongruity of the joint. These data may be used for numerical calculations, analysing the effects of incongruity on the joint stress and on the functional adaptation of the subarticular tissues.     

A social learning model of consultation.

Presents a model of consultation based on A. Bandura's (1977) social learning theory. The philosophical assumptions of the model, which are drawn from reciprocal determinism, are presented, as are the roles and principles that govern this model. The consulting process, which involves relationship building, assessment, problem statement, goal setting, intervention, and evaluation, is also described. Implications of the model for consultants are discussed, an illustrative case vignette is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stress induced hydrogen redistribution in commercial titanium alloys

The change in hydrogen concentration as a function of applied strain has been studied in commercial titanium alloys that included threeβ-phase, twoα-phase, and an (α + β)-phase Ti-6Al-4V alloy with differingα/β morphologies.Insitu measurements were made using a nondestructive nuclear technique on samples for which uniaxial compressive and tensile stresses were applied by four-point bending. Theβ-phase alloys exhibited hydrogen redistribution under an elastic stress gradient, but no further change was discernible accompanying plastic deformation. The extent of hydrogen concentration change for theβ-phase alloys was of the order of 4 to 6 pct for a 620 MPa stress gradient. This is less than would be predicted based on available data for the partial molal volume of hydrogen. Diffusion coefficients in a stress gradient were also determined and are consistent with those measured inβ-phase titanium at elevated and room temperatures. Within the experimental sensitivities there was no evidence of hydrogen redistribution with applied stress for theα-phase and Ti-6Al-4V alloys.     

The Role of Scale Stresses in the Sulfidation of Steels

Several high-temperature processes in chemical,petrochemical, and energy-processing industry arecharacterized by H₂S-containing atmospheres,confronting engineers with severe corrosion attack ofthe metallic components. Sulfidation is observed onmaterials used for heat exchangers within theheat-recovery zones. The damage is originated not onlyby the relatively fast growth rates of the sulfidescales, but is also due to the loss of their limitedprotective effect by cracking. Scale failure, as aconsequence of stresses generated during scale growthand by temperature changes, was investigated on a carbon steel, a low-chromium steel (1Cr-0.4Mo, T12),a ferritic-chromium steel (12Cr-1Mo), and on austeniticsteel (18Cr-9Ni, AISI 321). The experiments in thetemperature range 400-600°C (700°C), withsubsequent cooling to ambient temperature, wereaccompanied by acoustic-emission measurements in orderto detect scale cracking. Critical parameters for scalefailure are presented.