Characterization of Austempered Ductile Iron Through Barkhausen Noise Measurements

The outstanding mechanical properties of austempered ductile irons (ADI) are linked to the microstructure of the matrix obtained by subjecting a ductile iron with an appropriate composition to a heat treatment called austempering. Then the microstructure of the matrix consists of bainitic ferrite with different volume fractions of retained austenite. The aim of this work is to use the magnetic Barkhausen noise (MBN) as a nondestructive method for characterizing the microstructure of ADI. First, it is shown that the amplitude and position of the peak-shaped MBN response is quite sensitive to the microstructure of the matrix of ductile irons. Thus each type of constituent (equiaxial ferrite, pearlite, martensite or bainite) exhibits a typical response and, in turn, it can be identified from the MBN response. Furthermore, a good correlation is found between MBN signal parameters and ADI heat treatment parameters, indicating that MBN is also quite sensitive to fine evolutions of the microstructure of ADI. MBN peak position is especially sensitive to the type of bainite, whereas peak amplitude is linked to the progress of the bainite reaction. Hence MBN measurements appear to be a powerful tool to assess some important microstructural features of ADI castings.     

Clinical applications compared in implantology

On the basis of their own experience and of orientation reported by literature, the authors display how important it is for professional men who practise implantology or who approach it, to have the possibility of knowing several implantologic systems. Indeed, what we want to demonstrate is, that in different situations of edentulous, in relation to the quantity and the quality of the available bones, to the gnotologic situation and to the aesthetic functional result they aim to, corresponds the choice of one or several implantologic systems. In that sense the basic research occupies a role of vital importance, because only through the knowledge of chemical, chemical-physical and biomechanical characteristics it is possible to recognize some essential chemical entities for an implantologic approach. Thus the several diagnostic instrumental means available enable the surgeon to make an exact clinical diagnosis. The TAC, in this case, assumes a determinant role, because, in addition to supplying exact dimensional and qualitative informations, also occupies an important medico-legal aspect. The resolution of some forms of edentulous programmed like that, will subsequently be illustrated. Finally, a control hypothesis is proposed for the rearrangement, of peri-implant bone. On this account, the SPECT (single photon emission computerized tomography), through a semi-quantitative research, could provide some specific indications about the osteotropic implantation activity.     

Effects of temperature, ammonium and glucose concentrations on yeast growth in a model wine system

In enology, alcoholic fermentation is a complex process involving several mechanisms. Slow and incomplete alcoholic fermentation is a chronic problem for the wine industry and factors leading to sluggish and stuck fermentations have been extensively studied and reviewed. The most studied cause of sluggish and stuck fermentation is the nitrogen content limitation. Nevertheless, other factors, such as temperature of fermentation and sugar concentration can affect the growth of yeasts. In this study we modelled the yeast growth‐cycle in wine model system as a function of temperature, sugar and ammonium concentrations; the individual effects and the interaction of these factors were analysed by means of a quadratic response surface methodology. Cell concentrations and weight loss were monitored in the whole wine fermentation process. The results of central composite design show that lower is the availability of nitrogen, higher is the cell growth rate; moreover, initial nitrogen concentration also influences survival time of Saccharomyces cerevisiae.     

Processing and retention of complex auditory stimuli in monkeys (Cebus apella).

Four monkeys were trained to discriminate between "tunes" that differed primarily in their temporal structure, or frequency envelopes. The conclusion drawn from a variety of transfer tests was that they learned the discrimination on the basis of local features of the tunes rather than on their temporal patterns. Subsequent comparisons of retention based on auditory–visual and visual–visual matching tasks suggested that this deficiency was not due to a truncated auditory short-term store. Indeed, when previous experience with remembering visual and auditory stimuli was comparable, short-term memory also seemed comparable in the 2 modalities. It is noted that the ability to discriminate and employ the frequency contours of tonal patterns may be related to the capacity for acoustically based language, and that in the human infant, these skills seem to develop in parallel. (French abstract) (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A neuropsychological approach to school psychology.

Reviews advances in clinical neuropsychology and how they can be integrated into school psychology training and practice. Neuropsychological techniques, such as perinatal assessment, neuropsychological symptomatology, and the mental status examination, are evaluated in light of the school psychologist's role and function. Training models in neuropsychology are reviewed, with emphasis on school psychology training programs that offer specialization in neuropsychology. Future directions in pediatric/school neuropsychology are addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photoluminescence of hydrophilic silicon nanocrystals in aqueous solutions

Stable aqueous solutions of undecylenic-acid-grafted silicon nanocrystals (Si-nc) were prepared. The time evolution of the photoluminescence properties of these hydrophilic silicon nanocrystals has been followed on different timescales (hours and days). On a short timescale (hours), Si-nc tend to agglomerate while the PL lineshape and intensity are stable. Agglomeration can be reduced by using suitable surfactants. On a long timescale (days), oxidation of Si-nc occurs even in the presence of surfactants. These two observations render Si-nc very useful as a labeling agent for biosensing.     

High efficiency long pulse FIR Raman conversion in ammonia

Generally the quantum efficiency of FIR Raman generation in molecular gases is below the theoretical value. This disagreement is particularly evident in Raman scattering from pulsed sources with short pulse length, when the vibrational saturation limits the power conversion. Other nonlinear processes can overcome this saturation, but they require a very intense pump power for too short a time to use the FIR radiation in high sensitive experiments with heterodyne detection. This is the case, for instance, of RFWM. In this work we describe the experimental conditions to achieve a high efficiency 90 micron Raman conversion in ammonia, with both short and long pulses.     

Neuropsychological slowness in obsessive-compulsive patients. Is it confined to tests involving the fronto-subcortical systems?

BACKGROUND: Although it is acknowledged that obsessive-compulsive (OC) patients may be slower than healthy controls in performing neuropsychological tests, speed has usually been treated as a confounding variable. It is possible, however, that the slower performance of OC patients is itself the result of a dysfunction of specific neural circuits (in particular of fronto-subcortical systems). METHOD: A neuropsychological battery including tests sensitive to fronto- and temporo-subcortical dysfunction was administered to a group of OC patients and a group of healthy controls. Each test provided independent indices of accuracy and speed. RESULTS: OC patients were significantly slower than controls only when performing tasks involving the fronto-subcortical systems, whereas they did not differ from controls with respect to accuracy indices. CONCLUSION: It may be that neuropsychological slowness of OC patients is not merely an epiphenomenon of meticulous concern for correct test execution or intrusion of obsessive thoughts, but reflects the dysfunction of fronto-subcortical systems.