High-temperature spectral emissivity of several refractory elements and alloys

Thermionic energy conversion has emerged as the method of choice for the direct space-based conversion of heat to electricity. An important parameter in the implementation of this method of direct energy conversion is the emissivity of the converter emitter and collector materials. This information is necessary to determine heat losses, heat transfer, and reservoir temperatures in the thermionic energy converter. Spectral normal emissivities were acquired at a wavelength of 0.65 ώm for a series of tungsten-rhenium alloys, tungsten-osmium alloys, and tungsten-iridium alloys in the temperature range 1400 to 2600 K. Additionally, the spectral normal emissivity for pure elements of molybdenum and ruthenium were obtained over the temperature range 1200 to 2600 K and 1400 to 2250 K, respectively. The spectral normal emissivities for a niobium-67% ruthenium (eutectic composition) in the temperature range 1400 to 2000 K were also obtained at the same wavelength. In all cases, the emissivity decreased linearly with increasing temperature. Both the tungsten-osmium and the tungsten-rhenium alloys exhibited emissivity values of 0.32 to 0.54 over the temperatures tested. The tungsten-iridium alloy yielded emissivity data of 0.35 to 0.47. The niobium-ruthenium emissivity data were within 0.34 and 0.36. The pure molybdenum and pure ruthenium experiments resulted in emissivity values ranging from 0.35 to 0.45 and 0.35 to 0.39, respectively.     

Heavily brominated and highly unsaturated derivatives of jojoba oil

Two hexabromojojoba isomers were prepared by bromine addition to bromo-olefinic and bromoallylic derivatives, and an octabromojojoba derivative was prepared from jojobatetraene. Bis-allylic bromination of jojoba wax or monoallylic bromination of jojobatetraene, both followed by HBr elimination, yielded jojobahexaene, which has two conjugated triene units on both parts of the ester. Bromine addition to jojobahexaene yielded dodecabromojojoba, which was unstable toward hydrolysis in water-decalin mixture at 120C., This is in contrast to the relative stability of the octabromojojoba under these conditions. This paper is the fifth in a series of functionalization at the double bond region of jojoba oil.     

Studies of the Cis,Cis-Cyclodeca-1,6-Diene System

In the course of attempting to synthesize cyclodeca-1,6-diyne (IIIa) from cis, cis-cyclodeca-1,6-diene (XIX) derivatives by a successive bromination and dehydrobromination, transannular addition of one mole of bromine to the diene system occurred. The reaction products were bicyclic decalin derivatives. New symmetric and unsymmetric derivatives of XIX were prepared. Various approaches towards obtaining [10]annulene-quinone (XXIX) are reported.     

Functionalization at the double bond region of jojoba oil: I. bromine derivatives

Addition of bromine to jojoba oil and itstrans-isomer yielded tetrabromojojoba, which upon elimination afforded the acetylenic and allenic components, respectively, when reacted with excess of base. The bromoolefinic products were obtained when limited amount of base was used. Allylic bromination of the liquid wax and itstrans-isomer, and subsequent HBr elimination, yielded the two conjugated diene systems on both parts of the ester (jojoba tetraene).     

Sex pheromone of European grapevine moth (Lobesia botrana) its chemical transformations in sunlight and heat

Photo- and radical isomerization of (E, Z)-7,9-dodecadien-1-yl acetate (DDA) leads to an equilibrium mixture of all four possible geometric isomers of 7,9-DDA in the ratio ofE,E, 69–76%;Z,E, 11–13%;E, Z, 12–15%; andZ, Z, 1–3%. Iodine catalysis of the isomerization takes place even in dark at room temperature and is probably a radical reaction.     

Architectural tradeoffs for reconfigurable dense wavelength-division multiplexing systems

Advances in optical technology now allow practical reconfigurable wavelength networks to be constructed. These networks use wavelength-switching components to dynamically route wavelengths, and provide a level of flexibility and scalability previously not possible. Other components such as low-noise optical amplifiers, electronic dispersion compensators, and advanced modulation techniques simplify system operation, increase capacity, and extend reach. From an application perspective, the architecture of optical transport networks is evolving based on the requirement to support a higher bandwidth access infrastructure. The network architecture also needs to provide the flexibility to incrementally expand on the basis of customer demand and to provide key features such as optical broadcast to lower the cost of video services. The development of new architectures for optical transport networks and how these networks are influenced by critical system parameters and emerging component technologies is reviewed.     

Computational and Biochemical Design of a Nanopore Cleavable by a Cancer‐Secreted Enzyme

Many proteinaceous macromolecules selectively transport substrates across lipid bilayers and effectively serve as gated nanopores. Here, we engineered cleavage‐site motifs for human matrix metalloprotease 7 (MMP‐7) into the extracellular and pore‐constricting loops of OprD, a bacterial substrate‐specific transmembrane channel. Concurrent removal of two extracellular loops allowed MMP‐7 to access and hydrolyze a cleavage‐site motif engineered within the pore's major constricting loop, in both membrane‐incorporated and detergent‐solubilized OprDs. Import of antibiotics by the engineered OprDs into living bacteria pointed to their proper folding and integration in biological membranes. Purified engineered OprDs were also found to be properly folded in detergent. Hence, this study demonstrates the design of nanopores with a constriction cleavable by tumor‐secreted enzymes (like MMP‐7) for their potential incorporation in lipid‐based nanoparticles to accelerate drug release at the tumor site.     

Collaborative privacy preserving multi-agent planning

In many cases several entities, such as commercial companies, need to work together towards the achievement of joint goals, while hiding certain private information. To collaborate effectively, some sort of plan is needed to coordinate the different entities. We address the problem of automatically generating such a coordination plan while preserving the agents’ privacy. Maintaining privacy is challenging when planning for multiple agents, especially when tight collaboration is needed and a global high-level view of the plan is required. In this work we present the Greedy Privacy-Preserving Planner (GPPP), a privacy preserving planning algorithm in which the agents collaboratively generate an abstract and approximate global coordination plan and then individually extend the global plan to executable plans. To guide GPPP, we propose two domain independent privacy preserving heuristics based on landmarks and pattern databases, which are classical heuristics for single agent search. These heuristics, called privacy-preserving landmarks and privacy preserving PDBs, are agnostic to the planning algorithm and can be used by other privacy-preserving planning algorithms. Empirically, we demonstrate on benchmark domains the benefits of using these heuristics and the advantage of GPPP over existing privacy preserving planners for the multi-agent STRIPS formalism.