463 research outputs found

    Structure of 2,9-dimethyl-1,10-phenanthroline hemihydrate

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    C14H12N2•½H2O, Mr = 217•27, tetragonal I41/a, a = 14•258 (3), c = 22•286 (4) Å, V = 4531 (3) Å3, Z = 16, Dx = 1•274 (1) g cm-3, Mo Kα radiation λ = 0•71073 Å, µ = 0•74 cm-1, F(000) = 1840, T = 297 K, R = 0•041 for 1196 unique observed reflections with I \u3e 2σ(I). Pairs of dimethylphenanthroline molecules related by a twofold axis are bridged by water molecules lying on the twofold axis and H bonded to one of the N atoms in each molecule. The H bonds are long and far from linear: O—H 1•06 (4), H•••N 154 (3)°. This is presumably a consequence of the approximately parallel arrangement of the two phenanthroline molecules in the (phen)2.H2O complex, which are tilted 4•7 (1)° with respect to each other; the atoms in one molecule are 3•50 to 3•81 Å from the plane of the other molecule. On the other side of the phenanthroline is another phenanthroline related by a center of symmetry with the atoms of one molecule 3•41 to 3•45 Å from the plane of the other molecule. The phenanthroline molecule has close to 2mm symmetry, but the individual C6 rings are tilted about 1° with respect to each other

    Single-strain-gage force/stiffness buckling prediction techniques on a hat-stiffened panel

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    Predicting the buckling characteristics of a test panel is necessary to ensure panel integrity during a test program. A single-strain-gage buckling prediction method was developed on a hat-stiffened, monolithic titanium buckling panel. The method is an adaptation of the original force/stiffness method which requires back-to-back gages. The single-gage method was developed because the test panel did not have back-to-back gages. The method was used to predict buckling loads and temperatures under various heating and loading conditions. The results correlated well with a finite element buckling analysis. The single-gage force/stiffness method was a valid real-time and post-test buckling prediction technique

    The Economic Impact of North Dakota's Health Care Industry on the State's Economy in 1991

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    The health care industry's far-reaching economic influence within North Dakota is the focus of this report. An input-output model is used to estimate the economic impact of hospitals and long-term care nursing facilities. The analysis shows that nearly 8 percent of the state's total business activity, nearly 10 percent of the state's total retail sales, and nearly 19 percent of the state's total employment in 1991 were attributable to hospitals and long-term care nursing facilities. In addition, these facilities generated nearly $41 million of tax revenues for the state in 1991.Health Economics and Policy,

    Neural plasticity expressed in central auditory structures with and without tinnitus

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    Sensory training therapies for tinnitus are based on the assumption that, notwithstanding neural changes related to tinnitus, auditory training can alter the response properties of neurons in auditory pathways. To assess this assumption, we investigated whether brain changes induced by sensory training in tinnitus sufferers and measured by electroencephalography (EEG) are similar to those induced in age and hearing loss matched individuals without tinnitus trained on the same auditory task. Auditory training was given using a 5 kHz 40-Hz amplitude-modulated (AM) sound that was in the tinnitus frequency region of the tinnitus subjects and enabled extraction of the 40-Hz auditory steady-state response (ASSR) and P2 transient response known to localize to primary and non-primary auditory cortex, respectively. P2 amplitude increased over training sessions equally in participants with tinnitus and in control subjects, suggesting normal remodeling of non-primary auditory regions in tinnitus. However, training-induced changes in the ASSR differed between the tinnitus and control groups. In controls the phase delay between the 40-Hz response and stimulus waveforms reduced by about 10° over training, in agreement with previous results obtained in young normal hearing individuals. However, ASSR phase did not change significantly with training in the tinnitus group, although some participants showed phase shifts resembling controls. On the other hand, ASSR amplitude increased with training in the tinnitus group, whereas in controls this response (which is difficult to remodel in young normal hearing subjects) did not change with training. These results suggest that neural changes related to tinnitus altered how neural plasticity was expressed in the region of primary but not non-primary auditory cortex. Auditory training did not reduce tinnitus loudness although a small effect on the tinnitus spectrum was detected

    Key Residues Defining the Μ-Opioid Receptor Binding Pocket: A Site-Directed Mutagenesis Study

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    Structural elements of the rat Μ-opioid receptor important in ligand receptor binding and selectivity were examined using a site-directed mutagenesis approach. Five single amino acid mutations were made, three that altered conserved residues in the Μ, Δ, and Κ receptors (Asn 150 to Ala, His 297 to Ala, and Tyr 326 to Phe) and two designed to test for Μ/Δ selectivity (Ile 198 to Val and Val 202 to Ile). Mutation of His 297 in transmembrane domain 6 (TM6) resulted in no detectable binding with [ 3 H]DAMGO ( 3 H-labeled d-Ala 2 , N -Me-Phe 4 ,Gly-ol 5 -enkephalin), [ 3 H]bremazocine, or [ 3 H]ethylketocyclazocine. Mutation of Asn 150 in TM3 produces a three- to 20-fold increase in affinity for the opioid agonists morphine, DAMGO, fentanyl, Β-endorphin 1–31 , JOM-13, deltorphin II, dynorphin 1–13 , and U50,488, with no change in the binding of antagonists such as naloxone, naltrexone, naltrindole, and nor-binaltorphamine. In contrast, the Tyr 326 mutation in TM7 resulted in a decreased affinity for a wide spectrum of Μ, Δ, and Κ agonists and antagonists. Altering Val 202 to Ile in TM4 produced no change on ligand affinity, but Ile 198 to Val resulted in a four- to fivefold decreased affinity for the Μ agonists morphine and DAMGO, with no change in the binding affinities of Κ and Δ ligands.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65474/1/j.1471-4159.1997.68010344.x.pd

    Molecular basis for dynorphin A selectivity: A chimeric study

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31194/1/0000096.pd

    Kinetic Phenomena in Thin Film Electronic Materials

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    Contains reports on ten research projects.Semiconductor Research Corporation (Grant 83-01-033)National Science Foundation (Grant DMR 81-19285)U.S. Department of Energy (Contract DE-ACO2-82-ER-13019)National Science Foundation (Grant ECS82-05701)International Business Machines, Inc.Dartmouth UniversityJoint Services Electronics Program (Contract DAAG29-83-K-0003
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