Trisneopentylgallium as a precursor for atomic layer epitaxy of GaAs

We report the use of a new precursor, trisneopentylgallium (NPG) for the growth of GaAs by atomic layer epitaxy (ALE). In contrast to most other alkyl gallium precursors such as triethylgallium, which decompose via a β-hydride elimination mechanism, this compound undergoes homolysis similar to that of trimethylgallium (TMGa), the normal choice as an ALE precursor. Clear self-limiting growth behavior similar to that of TMGa was observed over a reasonably wide range of growth conditions (430–500°C). Carbon incorporation was not significantly reduced compared with TMGa suggesting that the adsorbed neopentyl radicals undergo decomposition to result in a methyl terminated surface identical to that obtained for growth with TMGa.     

Neurocalcin immunoreactivity in the rat main olfactory bulb

The morphological characteristics and distribution of neurocalcin (NC)-immunoreactive elements were studied in the rat main olfactory bulb (OB) using a polyclonal antibody and the avidin-biotin immunoperoxidase method. NC-positive elements were abundant in the glomerular layer (GL), where numerous immunostained external tufted cells and periglomerular cells were detected. Other less abundant NC-immunolabeled populations included middle and internal tufted cells, Van Gehuchten cells, horizontal cells, vertical cells of Cajal, deep short-axon cells and granule cells. This study demonstrates the presence of NC immunoreactivity in subsets of different neuronal types in the rat main OB. This calcium-binding protein has been found in interneurons, and no evidence of immunoreactivity to NC is detected in projecting neurons. Despite the large population of labeled external tufted cells, most of them belong according to morphological criteria to the local circuit group and some others to those with interbulbar and/or intrabulbar connections. The identification of neuronal subpopulations expressing NC provides a further characterization and shows the existence of biochemical differences within morphologically identical neurons. Thus, this marker may be a useful tool in unravelling the circuitries of the rodent OB in both normal and experimental conditions. The exact physiological function of NC in the olfactory system remains unknown. On the basis of similarities to recoverin, it could be involved in mechanisms responsible for sensory adaptation. Additionally, its calcium-binding abilities may contribute to improve the temporal precision of stimuli transmission, or be concerned with general calcium-related events occurring in specific interneuronal groups.     

Electromagnetic compatibility aspects of active robotic systems for surgery: the robotic prostatectomy experience

This case describes ventricular proarrhythmia as a result of a synchronized internal atrial defibrillation shock in a 29-year-old man with Ebstein's anomaly referred for radiofrequency ablation of a right posterior accessory pathway. During the electrophysiologic study, atrial fibrillation was induced and 3/3 msec shocks of various strengths were delivered between two decapolar defibrillation catheters in the coronary sinus and right atrial appendage. A 2.0-J biphasic shock synchronized to an R wave after a short-long-short ventricular cycle length pattern with a preshock coupling interval of 245 msec induced ventricular fibrillation, which was externally defibrillated with 200 J. This observation has implications for the development of implantable atrial defibrillators.     

Electronic and phonon properties of the full-Heusler alloys X<Subscript>2</Subscript>YAl (X = Co,Fe and Y = Cr,Sc): a density functional theory study

First-principle calculations have been carried out on the structural, electronic, elastic, and phonon properties of the full-Heusler alloys X₂YAl (X = Co, Fe and Y = Cr, Sc). The calculations predict that the Fe₂CrAl and Co₂CrAl are half-metallic ferromagnets at the equilibrium lattice constant with a minority-spin energy gap of 0.2912 and 0.668 eV, respectively. Fe₂ScAl exhibit a gap in the majority density of states, with a few states at the Fermi level and about 0.217 states eV^?1, unlike the other Heusler compounds; due to this, it is considered a false half metal, and Co₂ScAl is considered a non-magnetic compound. The elastic constants were derived from the slopes of the acoustic branches in the phonon-dispersion curve. The calculated lattice constants, bulk modulus, and first-order pressure derivative of the bulk modulus are reported for the L2₁ structure and compared with previous values. Phonon-dispersion curves were obtained using the first-principle linear-response approach of the density-functional perturbation theory. The specific heat capacity at a constant volume C _V of X₂YAl (X = Co, Fe and Y = Cr, Sc) alloys is calculated and discussed.     

How accurately do drivers evaluate their own driving behavior? An on-road observational study

Self-assessment of driving skills became a noteworthy research subject in traffic psychology, since by knowing one's strenghts and weaknesses, drivers can take an efficient compensatory action to moderate risk and to ensure safety in hazardous environments. The current study aims to investigate drivers’ self-conception of their own driving skills and behavior in relation to expert evaluations of their actual driving, by using naturalistic and systematic observation method during actual on-road driving session and to assess the different aspects of driving via comprehensive scales sensitive to different specific aspects of driving. 19–63 years old male participants (N = 158) attended an on-road driving session lasting approximately 80 min (45 km). During the driving session, drivers’ errors and violations were recorded by an expert observer. At the end of the driving session, observers completed the driver evaluation questionnaire, while drivers completed the driving self-evaluation questionnaire and Driver Behavior Questionnaire (DBQ). Low to moderate correlations between driver and observer evaluations of driving skills and behavior, mainly on errors and violations of speed and traffic lights was found. Furthermore, the robust finding that drivers evaluate their driving performance as better than the expert was replicated. Over-positive appraisal was higher among drivers with higher error/violation score and with the ones that were evaluated by the expert as “unsafe”. We suggest that the traffic environment might be regulated by increasing feedback indicators of errors and violations, which in turn might increase the insight into driving performance. Improving self-awareness by training and feedback sessions might play a key role for reducing the probability of risk in their driving activity.     

The use of ethanol–gasoline blend as a fuel in an SI engine

One of the major problems for the successful application of gasoline–alcohol mixtures as a motor fuel is the realization of a stable homogeneous liquid phase. To overcome this problem, a new carburetor was designed. With the use of this new carburetor, not only the phase problem was solved but also the alcohol ratio in the total fuel was increased.By using ethanol–gasoline blend, the availability analysis of a spark-ignition engine was experimentally investigated. Sixty percent ethanol and 40% gasoline blend was exploited to test the performance, the fuel consumption, and the exhaust emissions.As a result of this study, it is seen that a new dual fuel system could be serviceable by making simple modifications on the carburetor and these modifications would not cause complications in the carburetor system.     

Cleaning Method of InSb [-1-1-1] B of n- InSb [111] A/B for growth of epitaxial layers by liquid phase epitaxy

The crystal structure of InSb [111] A/B surfaces shows that this structure is polarized. This means that the surfaces of InSb [111] A and InSb [1 1 1] B contain two different crystallized directions and they have different physical and chemical properties. Experiments were carried out on the InSb [111] A/B surfaces, showing that tartaric acid etchant could create a very smooth surface on the InSb [1 1 1] B without any traces of oxides and etch pit but simultaneously create etch pit on InSb [111] A surfaces. After lapping and polishing, some particles remained on the InSb [1 1 1] B surface, they could not be removed easily by standard cleaning process and if these particles remain on the surface of the substrate, the growth layer was not uniform and some island-like regions were observed. The purpose of this work is to remove these particles on the InSb [1 1 1] B surface. Some morphology images of both surfaces, InSb [111] A/B, will be presented.