AN Experimental Investigation of Nuclear Radiation Effects on Radar Receiver Components

Three ceramic tube 60-megacycle i-f amplifiers and one X-band mixer-preamplifier assembly were operated in the vicinity of a 3 megawatt nuclear reactor for a total of 300 megawatt hours, and their characteristics were monitored to determine the effects of nuclear radiation. There wrere essentially no changes in the characteristics of the i-f amplifiers throughout the test with a total integrated neutron flux of 2.8 × 1016 neutrons/ cm2 (Energy greater than 0.3 Mev) and a gamma dose of 3 × 1010 ergs/gm(C). The mixer-preamplifier operated with no noticeable changes to a total integrated neutron flux of 4 × 1015 neutrons/cm2 (Energy greater than 0.3 Mev) and gamma dose of 5.5 × 109 ergs/gm(C). Various degrees of degradation in crystal performance, gain, and noise characteristics were experienced throughout the remainder of the test.     

Potential of building-scale alternative energy to alleviate risk from the future price of energy

The energy used for building operations, the associated greenhouse gas emissions, and the uncertainties in future price of natural gas and electricity can be a cause of concern for building owners and policy makers. In this work we explore the potential of building-scale alternative energy technologies to reduce demand and emissions while also shielding building owners from the risks associated with fluctuations in the price of natural gas and grid electricity. We analyze the monetary costs and benefits over the life cycle of five technologies (photovoltaic and wind electricity generation, solar air and water heating, and ground source heat pumps) over three audience or building types (homeowners, small businesses, large commercial and institutional entities). The analysis includes a Monte Carlo analysis to measure risk that can be compared to other investment opportunities. The results indicate that under government incentives and climate of Toronto, Canada, the returns are relatively high for small degrees of risks for a number of technologies. Ground source heat pumps prove to be exceptionally good investments in terms of their energy savings, emission, reductions, and economics, while the bigger buildings tend also to be better economic choices for the use of these technologies.     

Fully embedded board-level guided-wave optoelectronic interconnects

A fully embedded board-level guided-wave optical interconnection is presented to solve the packaging compatibility problem. All elements involved in providing high-speed optical communications within one board are demonstrated. Experimental results on a 12-channel linear array of thin-film polyimide waveguides, vertical-cavity surface-emitting lasers (VCSELs) (42 μm), and silicon MSM photodetectors (10 μm) suitable for a fully embedded implementation are provided. Two types of waveguide couplers, titled gratings and 45° total internal reflection mirrors, are fabricated within the polyimide waveguides. Thirty-five to near 100% coupling efficiencies are experimentally confirmed. By doing so, all the real estate of the PC board surface are occupied by electronics, and therefore one only observes the performance enhancement due to the employment of optical interconnection but does not worry about the interface problem between electronic and optoelectronic components unlike conventional approaches. A high speed 1-48 optical clock signal distribution network for Cray T-90 super computer is demonstrated. A waveguide propagation loss of 0.21 dB/cm at 850 nm was experimentally confirmed for the 1-48 clock signal distribution and for point-to-point interconnects. The feasibility of using polyimide as the interlayer dielectric material to form hybrid three-dimensional interconnects is also demonstrated. Finally, a waveguide bus architecture is presented, which provides a realistic bidirectional broadcasting transmission of optical signals. Such a structure is equivalent to such IEEE standard bus protocols as VME bus and FutureBus     

Biological profile of L-745,870, a selective antagonist with high affinity for the dopamine D4 receptor

L-745,870,(3-([4-(4-chlorophenyl)piperazin-1-yl]methyl)-1H- pyrollo[2,3-b] pyridine, was identified as a selective dopamine D4 receptor antagonist with excellent oral bioavailability and brain penetration. L-745,870 displaced specific binding of 0.2 nM [3H] spiperone to cloned human dopamine D4 receptors with a binding affinity (Ki) of 0. 43 nM which was 5- and 20-fold higher than that of the standard antipsychotics haloperidol and clozapine, respectively. L-745,870 exhibited high selectivity for the dopamine D4 receptor (>2000 fold) compared to other dopamine receptor subtypes and had moderate affinity for 5HT2, sigma and alpha adrenergic receptors(IC50 < 300 nM). In vitro, L-745,870 (0.1-1 microM) exhibited D4 receptor antagonist activity, reversing dopamine (1 microM) mediated 1) inhibition of adenylate cyclase in hD4HEK and hD4CHO cells; 2) stimulation of [35S] GTPgammaS binding and 3) stimulation of extracellular acidification rate, but did not exhibit any significant intrinsic activity in these assays. Although standard antipsychotics increase dopamine metabolism or plasma prolactin levels in rodents, L-745,870 (相似文献   

Inhibition of shivering increases core temperature afterdrop and attenuates rewarming in hypothermic humans

During severe hypothermia, shivering is absent. To simulate severe hypothermia, shivering in eight mildly hypothermic subjects was inhibited with meperidine (1.5 mg/kg). Subjects were cooled twice (meperidine and control trials) in 8 degrees C water to a core temperature of 35.9 +/- 0.5 (SD) degrees C, dried, and then placed in sleeping bags. Meperidine caused a 3.2-fold increase in core temperature afterdrop (1.1 +/- 0.6 vs. 0.4 +/- 0.2 degree C), a 4.3-fold increase in afterdrop duration (89.4 +/- 31.4 vs. 20.9 +/- 5.7 min), and a 37% decrease in rewarming rate (1.2 +/- 0.5 vs. 1.9 +/- 0.9 degrees C/h). Meperidine inhibited overt shivering. Oxygen consumption, minute ventilation, and heart rate decreased after meperidine injection but subsequently returned toward preinjection values after 45 min postimmersion. This was likely due to the increased thermoregulatory drive with the greater afterdrop and the short half-life of meperidine. These results demonstrate the effectiveness of shivering heat production in attenuating the postcooling afterdrop of core temperature and potentiating core rewarming. The meperidine protocol may be valuable for comparing the efficacy of various hypothermia rewarming methods in the absence of shivering.     

Novel integrated optical polarisers using surface plasma waves and ion milled grooves in lithium niobate

Two distinctly different integrated optical polarisers have been made with multilayer claddings and titanium indiffused lithium niobate waveguides, transmitting both TE and TM polarisations. The TE device used claddings on the crystal surface obtaining (20.9±0.3) dB/cm extinction ratio. The TM polariser used similar claddings on a vertical wall fabricated by ion-beam milling adjacent to the waveguide, obtaining (17±3) dB extinction ratio.     

Electron-induced dissociation of singly charged organic cations as a tool for structural characterization of pharmaceutical type molecules

Collision-induced dissociation (CID) and electron-induced dissociation (EID) have been investigated for a selection of small, singly charged organic molecules of pharmaceutical interest. Comparison of these techniques has shown that EID carried out on an FTICR MS and CID performed on a linear ion trap MS produce complementary data. In a study of 33 molecule-cations, EID generated over 300 product ions compared to 190 product ions by CID with an average of only 3 product ions per precursor ion common to both tandem MS techniques. Even multiple stages of CID failed to generate many of the product ions observed following EID. The charge carrying species is also shown to have a very significant effect on the degree of fragmentation and types of product ion resulting from EID. Protonated species behave much like the ammonium adduct with suggestion of a hydrogen atom from the charge carrying species strongly affecting the fragmentation mechanism. Sodium and potassium are retained by nearly every product ion formed from [M + Na](+) or [M + K](+) and provide information to complement the EID of [M + H](+) or [M + NH(4)](+). In summary, EID is proven to be a fitting partner to CID in the structural elucidation of small singly charged ions and by studying EID of a molecule-ion holding different charge carrying species, an even greater depth of detail can be obtained for functional groups commonly used in synthetic chemistry.     

The effect of nickel,chromium, and primary

Elevated temperature creep tests were performed on Ti 6242Si deformed to small (<0.002) plastic strains using a highly aligned creep testing apparatus. Specimens were solution annealed at various temperatures below the beta transus(T _β - 6 °C toT _β − 52 °C) which controlled the volume fraction of primary alpha. Decreases in the amount of primary alpha are associated with decreased primary and steady-state creep rates. The effects of trace levels of the elements Ni and Cr on the creep properties of Ti 6242Si were also studied. Relatively small additions of Ni (0.075 to 0.093 wt pct), which appeared to segregate to the bcc beta phase, substantially in- creased the creep rates of this alloy, while additions of Cr up to 0.278 wt pct had little, if any, effect on the creep rates.