Synthesis and polymerization of anthracene‐based itaconimides

Two new anthracene‐based itaconimides, ie N‐(1‐ and 2‐anthryl) itaconimides, were synthesized by the reaction of aromatic amines with itaconic anhydride, followed by itaconamic acid imidization. The same reaction failed in the case of anthracene‐ring substitution at the position 9′. Radical and thermal polymerization of N‐(1‐ and 2‐anthryl) itaconimides led to polymers with anthracene pendant groups. No self‐polymerization by Diels–Alder cycloaddition of the itaconic function (dienophile) and anthracene nucleus (diene) was observed, as is the case for N‐(anthryl) maleimides and citraconimides. Copyright © 2004 Society of Chemical Industry     

Equivalent linearization for Poisson white noise input

Methods are developed for calculating characteristic functions and mean upcrossing rates of the response of linear systems to α-stable input processes. The methods are based on the integral and series representations of these processes. The integral representation resembles the spectral representation of wide-sense stationary processes. The α-stable processes are non-Gaussian and have no moments of order two and higher. Therefore, classical methods of linear random vibration for calculating the mean and covariance functions of the response from the corresponding functions of the input do not apply. Applications are presented to illustrate the proposed methods of analysis.     

1.55 mu m multiquantum-well lasers with record performance obtained by atmospheric pressure MOVPE using organometallic phosphorus precursor

The recently available precursor biphosphinoethane (BPE) was used, alongside with phosphine and with tertbutylphosphine (TBP), to grow advanced multiquantum-well (MQW) laser wafers with five quaternary, compressive strained wells. The lowest threshold current densities and the lowest optical losses were obtained with BPE. In particular, the lowest threshold current density, 328 A/cm/sup 2/, is a record among published values for lasers with five wells. In this comparison, the wafer grown with phosphine came a close second and that grown with TBP was third.<>     

Long Range Self‐Assembly of Polythiophene Breath Figures: Optical and Morphological Characterization

Large‐area, device relevant sized microporous thin films are formed with commercially available polythiophenes by the breath figure technique, a water‐assisted micropatterning method, with such semitransparent thin films exhibiting periodicity and uniformity dictated by the length of the polymer side chain. Compared to drop‐casted thin films, the microporous thin films exhibit increased crystallinity due to stronger packing of the polymer inside the honeycomb frame.     

Stacked GaAs quantum dots fabricated by refilling of self-organized nanoholes: optical properties and post-growth annealing

We study the photoluminescence and impact of post-growth annealing of stacked, strain-free GaAs quantum dots fabricated by refilling of self-organized nanoholes using molecular beam epitaxy. Temperature- and power-dependent photoluminescence studies reveal an excellent optical quality of the quantum-dot stack. After high-temperature post-growth annealing only slight blueshifts and an increase in full width at half-maximum of the photoluminescence peak are observed, indicating very high-temperature stability and crystalline quality of the stacked GaAs quantum-dot structure.     

Tandem ion trap design with enhanced mass analysis capabilities for large populations of ions

A new arrangement consisting of two separate radio frequency (rf) quadrupole ion traps is used to analyze large populations of ions over a wide mass-to-charge (m/z) range. The setup consists of an "accumulation" trap that is maintained at a higher pressure than the second high-performance "analyzer" trap. The two traps are scanned simultaneously, with a mass difference between that determines the residence time and mass range of ions in the analytical trap. Initially, all ions are trapped in the accumulation trap and then mass-selectively ejected into the analyzer trap. As ions arrive in the analyzer trap, they cool through collisions with the buffer gas and then are mass selectively ejected toward the detector. This concurrent linked mass scanning reduces the total number of ions present in the analyzer trap during mass analysis, thereby reducing space charge effects and leading to improved resolution and mass accuracy of analytical spectra.     

Synthesis and characterization of a fully aromatic polyazomethine with rotaxane architecture

This paper reports the preparation and characterization of a new aromatic polyazomethine with rotaxane architecture. The complex of β‐cyclodextrin and 1,4‐phenylenediamine was treated with N‐n‐butyl‐3,6‐diformylcarbazole, which is large enough to prevent dethreading. The polycondensation reaction was performed in N,N‐dimethylformamide leading to polyazomethine soluble in polar solvents. Measurements made by gel permeation chromatography of the dimethylformamide‐soluble (DMF) soluble polyazomethine show the presence of high molecular weight material. The structure and thermal properties of the resulting polymer were characterized by IR, ¹H NMR, TGA and DSC techniques. Copyright © 2003 Society of Chemical Industry     

Penny-shaped crack in a transversely isotropic solid

An analytical solution is given for the displacement and stress distribution produced in the interior of a transversely isotropie solid containing a penny-shaped crack situated in an elastic symmetry plane and axially-loaded. Curves of numerical results are presented for the stress intensity factor and the normal displacement. They show the influence of this type of anisotropy.     

Combined, but not single, gustatory nerve transection substantially alters taste-guided licking behavior to quinine in rats.

On the basis of electrophysiological studies, the glossopharyngeal nerve (GL) is far more responsive to quinine than the chorda tympani (CTP) or greater superficial petrosal (GSP) nerves. The licking behavior of 72 male, water-deprived rats to quinine (0.03–3.0 mM) and distilled water (10-sec trials) was tested before and after various nerve transections. GL?+?CTP section caused a substantial reduction in responsiveness. GSP?+?CTP section had a moderate effect, and GL section alone produced only marginal impairments. Control, partially desalivated, and CTP-sectioned rats were unaffected. Thus, the GL is not necessary for normal unconditioned taste-guided appetitive responsiveness to quinine, but the collective input from the GSP and CTP is necessary and most likely sufficient. These data suggest that the quinine-evoked input of the GL and CTP converge centrally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)