Compositional non-uniformities in selective area growth of GaInAs on InP grown by OMVPE

Selective area epitaxial growth of Ga_0.47In_0.53As on InP substrates patterned with silicon nitride was done by low pressure organometallic vapor phase epitaxy. Good surface morphology and clean side walls of the epitaxial layers were obtained in most of the areas of selective GalnAs growth. However, both GaAs incorporation and InAs incorporation increased near the edges of the selective growth areas due to the extra flux of Gacontaining and In-containing species migrating on the surface of silicon nitride. The increase in InAs incorporation was found at a higher rate when the adjacent silicon nitride area was large, hence, cross-hatching appeared near the edges. A characteristic length of adjacent silicon nitride seemed to be connected with the enhanced InAs incorporation, which was about 40μm at 600°. The non-uniformities in composition appeared in all wafers grown in the temperature range between 570 and 650°.     

Evaluation of the Canadian Coordinating Office for Health Technology Assessment

The Canadian Coordinating Office for Health Technology Assessment (CCOHTA) was recently evaluated. We summarize the evaluation process, report, and 17 recommendations for enhancing CCOHTA's effectiveness. This paper may be useful for evaluators of agencies for technology assessment.     

Inactivation of cytochrome P450 2E1 by tert-butylisothiocyanate

Several naturally occurring and synthethic isothiocyanates were evaluated for their ability to inactivate the major ethanol-inducible hepatic cytochrome P450 2E1. Of the compounds tested, tert-butylisothiocyanate (tBITC) was found to be the most selective inactivator of the 2E1 p-nitrophenol hydroxylation activity. tBITC was more specific for inactivating P450 2E1 activity than for rat P450 1A1, 1A2, 3A2, and 2B1, or the human cytochromes P450 3A4 and 2B6. The kinetics of inactivation of P450 2E1 by tBITC were characterized. P450 2E1, either in rat liver microsomes or in a purified reconstituted system containing the bacterially expressed rabbit cytochrome, was inactivated by tBITC in a mechanism-based manner. The loss of activity followed pseudo-first-order kinetics and was NADPH- and tBITC-dependent. The maximal rates for inactivation of P450 2E1 in microsomes or for the purified P450 2E1 at 30 degrees C were 0.72 and 0.27 min-1 and the apparent KI values were 11 and 7.6 microM, respectively. When cytochrome b5 was co-reconstituted with P450 2E1, the apparent KI for P450 2E1 inactivation by tBITC was similar to that seen in microsomes (14 microM). P450 2E1 T303A was also inactivated by tBITC with kinetic constants similar to that of the wild type enzyme. Co-incubations with an alternate substrate protected P450 2E1 from inactivation by tBITC. The extent of P450 2E1 inactivation by tBITC resulted in a comparable loss of the ability of the enzyme to form a reduced CO complex.     

Measurement and modeling of creep in open-cell NiAl foams

Nickel-rich NiAl foams, consisting of open cells with hollow struts and exhibiting two relative densities (5.0 and 6.6 pct) and average cell sizes (1.27 and 0.85 mm), were creep tested between 800 °C and 1100 °C under compressive stresses between 0.10 and 1.50 MPa. For stresses lower than 0.50 MPa, the foams exhibit secondary creep with power-law behavior characterized by creep exponents and activation energies close to those of bulk, nickel-rich NiAl. A three-dimensional (3-D) finite-element model (FEM) was implemented for a cell consisting of hollow struts on a cubic lattice, which predicts creep rates in reasonable agreement with the experimental data. Based on these numerical results, a simplified analytical model is proposed, whereby struts parallel to the applied stress deform by creep in a purely compressive mode, while perpendicular struts prevent buckling but provide no direct load-bearing capacity. This simple model produces results that are very close to the predictions of the complex numerical model and in good agreement with the experimental data. By contrast, an existing model considering creep bending of struts within the foam predicts strain rates that are too high by approximately two orders of magnitude.     

Synthesis and properties of compounds related to stilbazole

We report attempts to create conjugated polymers consisting of alternating phenylene and heterocyclic rings separated by double bonds by means of condensations between terephthalaldehyde and dimethyl nitrogen bases. Because the products precipitated during their formation even at 180°C in N-methyl-2-pyrrolidinone (NMP), only oligomers of up to ca. 30 rings (DP = 15) could be obtained; most of the adequately soluble products had DP between 4 and 8, and from these oligomers films on glass or quartz could be made. When the films were exposed to I₂, NO₂, or SbF₅, most of them, initially very good insulators, showed an increase in electrical conductivity of up to 6 powers of 10; but the rapid reversal of this change when the reagent evaporated and the lack of any clear changes in the UV-vis spectrum of the films showed that most likely true “doping” had not occurred. Extensive syntheses with a variety of quaternised bases also failed to yield oligomers oxidisable by electron-acceptors. For reference purposes, especially for their spectra, a large number of pure “model” compounds of the distyrylpyridine and distyrylpyrazine type, and quaternised analogues of the former, were synthesised, many of them new compounds. These were also used as calibrants for a GPC column operating with NMP solutions. Several improvements were made in the synthetic techniques.     

Results of a genome-wide genetic screen for panic disorder

There is some controversy over whether or not a discrete site that integrates vomiting activities in somatic and autonomic nerves is present in the medulla oblongata. On the basis of our previous studies, we hypothesized that the temporal patterns of muscle contractions in vomiting are generated by a central pattern generator in the retrofacial area of the rostral medulla. To investigate this hypothesis further, the effects of electrical and chemical lesions of the medullary area were observed in decerebrate paralyzed dogs. Efferent activities of the phrenic and abdominal muscle nerves were recorded to recognize fictive vomiting. The right half of the medulla oblongata was transversely severed about 3 mm rostral to the obex. Fictive vomiting responses to vagal stimulation still appeared after hemisection in all 11 dogs. In addition, stimulation of the contralateral reticular area dorsomedial to the retrofacial nucleus produced fictive vomiting even after hemisection. An electrical lesion or injection of kainic acid (0.5-1.0 microl) was applied at the point where reticular stimulation induced fictive vomiting. After this destruction, no activities that corresponded to fictive vomiting could be induced by stimulation of vagal afferents or the reticular site. Salivation was decreased by hemisection, and decreased further, but was not completely abolished, with destruction of the reticular area. Kainic acid is known to selectively destroy neural cell bodies. Therefore, we concluded that neuronal somata in the reticular formation dorsomedial to the retrofacial nucleus play an essential role in the central patterning of vomiting activities in peripheral motor nerves.     

Acquisition, retention, and extinction of operant discriminations in rats with nucleus basalis magnocellularis lesions.

Effects of bilateral ibotenic acid lesions of nucleus basalis magnocellularis (NBM) and scopolamine treatment on different aspects of learning and memory in an operant discrimination task were assessed. In Experiment 1, NBM lesions impaired acquisition performance. In Experiment 2, scopolamine lowered response rates but did not affect discrimination accuracy in lesioned or control rats. In Experiment 3, although pretrained rats showed transient increases in commission errors, percentage correct responding remained above chance levels after lesion. During extinction in Experiment 4, operant responding diminished more quickly in pretrained NBM-lesioned rats than in controls, but subsequent reacquisition performance was equivalent in both groups. Results suggest the NBM is importantly involved in discrimination learning, but cholinergic activity may be less critical for memory retention than for acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Service robot feature design effects on user perceptions and emotional responses

Service robots have been developed to assist nurses in routine patient services. Prior research has recognized that patient emotional experiences with robots may be as important as robot task performance in terms of user acceptance and assessments of effectiveness. The objective of this study was to understand the effect of different service robot interface features on elderly perceptions and emotional responses in a simulated medicine delivery task. Twenty-four participants sat in a simulated patient room and a service robot delivered a bag of “medicine” to them. Repeated trials were used to present variations on three robot features, including facial configuration, voice messaging and interactivity. Participant heart rate (HR) and galvanic skin response (GSR) were collected. Participant ratings of robot humanness [perceived anthropomorphism (PA)] were collected post-trial along with subjective ratings of arousal (bored–excited) and valence (unhappy–happy) using the self-assessment manikin (SAM) questionnaire. Results indicated the presence of all three types of robot features promoted higher PA, arousal and valence, compared to a control condition (a robot without any of the features). Participant physiological responses varied with events in their interaction with the robot. The three types of features also had different utility for stimulating participant arousal and valence, as well as physiological responses. In general, results indicated that adding anthropomorphic and interactive features to service robots promoted positive emotional responses [increased excitement (GSR) and happiness (HR)] in elderly users. It is expected that results from this study could be used as a basis for developing affective robot interface design guidelines to promote user emotional experiences.