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Notes: The semiclassical S-matrix theory of Miller and Marcus is utilized to derive an exact classical mechanical expression for the effective cross sections governing collisional depolarization and rotational relaxation in open-shell molecules with Σ electronic symmetry. These cross sections are expressed as a sum of products of classical dynamical terms (which may be evaluated by conventional Monte Carlo techniques) and geometrical terms that describe the quantum mechanical coupling of the angular momentum vectors in the open-shell molecule. All effects on rotational transitions due to the nonzero electronic spin angular momentum in the open-shell molecule are accounted for through the geometrical terms. Recently, sophisticated molecular beam and laser double resonance techniques have allowed the state-resolved study of rotational energy transfer in collisions involving open-shell molecules in their ground electronic state. The present extension of classical scattering theory provides the theoretical framework for an exact classical mechanical calculation of the collision dynamics in such experiments.

Notes: Superconductor digital devices using single-flux-quantum (SFQ) data encoding offer higher speed at lower power than any other integrated circuit technology. For this very reason, interconnect is challenging. We report SFQ data transfer between chips flip chip mounted on a passive microstrip carrier. The flip-chip structure achieves bandwidths greater than 250 GHz. Unlike previous designs, our signal lines are terminated at both ends; this is accomplished using a driver that produces a double-flux-quantum signal. We measured the circuit for pseudorandom data in the range of 10–60 Gb/s. Bit error rates are measured down to 1E−10 and extrapolate to negligible values. The signal power on the microstrip is only 30 nW at 60 Gb ps. © 2002 American Institute of Physics.

Notes: 1. The binding of l,3-[3H]-dipropyl-8-cyclopentylxanthine ([3H]-DPCPX), a specific adenosine Ai receptor antagonist, was examined in rat vas deferens membrane preparations using radioligand binding techniques.2. l,3-[3H]-Dipropyl-8-cyclopentylxanthine bound to these preparations with a KD of 1.07 ± 0.14 nmol/L (n = 6). The density of [3H]-DPCPX binding sites was 133.38 ± 5.57 fmol/mg protein.3. Computer analysis indicated that nucleosides competed for [3H]-DPCPX binding at two distinct sites. The rank order of potency at the higher affinity site corresponded to R-phenyliso-propyladenosine (R-PIA) 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 2-chloroadenosine (2-CI ADO) 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 cyclopentyladenosine (CPA) 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 N-ethylcarboxamidoadenosine (NECA)〉s-phenylisopropyladenosine (s-PIA). Kj values were in the low nmol/L range. The rank order of nucleoside potency at the lower affinity site corresponded to R-PIA 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉 CPA 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉NECA〉=2-ClADO〉 S-PIA. Ki values were in the low μmol/L range.4. Nucleotides competed for [3H]-DPCPX binding at a single site only. The rank order of potency at this site corresponded to a,β-methylene ATP 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉βγ-methylene ATP 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03051870:CEP492:ges" location="ges.gif"/〉= ATP. Ki values were in the high |xmol/L range. This site seemed to correspond with one of the two binding sites predicted by nucleoside competition binding.5. The ATP-regenerating compound myokinase did not significantly change the competition curve for ATP, indicating that the competition for [3H]-DPCPX binding observed in the presence of ATP was due to an effect of ATP per se and not to an action of a degradation product.6. The results demonstrate that in rat vasa deferentia there exist two distinct binding sites for [3H]-DPCPX. One of these sites binds only nucleosides and may represent an adenosine Ai receptor, as usually defined. The other site binds both nucleosides and nucleotides and may represent an atypical adenosine A1 receptor, an atypical P2 or a P3 purinoceptor.

Notes: The local structure around Mg2+ ions of a Magnesium substituted aluminophosphate, with the ATS structure (MgAPO-36, Mg/P=0.08), in the as-prepared and calcined state has been investigated by Mg K-edge XAS spectroscopy. High quality XAS data were collected using the solid-state fluorescence detector. Mg2+ is found to replace tetrahedrally co-ordinated Al3+ in the as-prepared state and remained intact even after calcination, thus yielding a highly active, solid acid catalyst.