Evaluation of a high temperature adhesive for fabricating graphite/PMR-15 polyimide structures

Tests are conducted to measure shear strength, shear modulus and flatwise tensile strength of the A7F (amide-imide modified LARC-13) adhesive system. An investigation is also conducted to determine the effect of geometric material parameters, and elevated temperature on the static strength of standard joints. Single-lap and double-lap composite joints, and single, double and step lap composite to metal joints are characterized. A series of advanced joints consisting of preformed adherends, adherends with scalloped edges and joints with hybrid interface plies are tested and compared to baseline single and double-lap designs

Bramble Fruit Culture

PDF pages: 1

Evaluation of high temperature structural adhesives for extended service

The preliminary evaluation of crosslinked polyphenyl quinoxaline (X-PPQ), LARC-TPI, ethyl terminated polysulfone (ETPS), and crosslinked polyimide (X-PI) as adhesives is presented. Lap shear strength stability under thermal, combined thermal/humidity, and stressed and unstressed Skydrol exposure was determined. The X-PPQ, LARC-TPI, and X-PI exhibited good adhesive performance at 505K (450 F) after 1000 hours at 505K. These three polymers also performed well after exposure to combined elevated temperature/high humidity, as well as, to Skydrol while under stress. The ETPS exhibited good ambient temperature adhesive properties, but performed poorly under all other exposure conditions, presumably due to inadequate chain extension and crosslinking

Grape Growing

PDF pages: 2

Resonant Tunneling in Truly Axial Symmetry Mn12 Single-Molecule Magnets: Sharp Crossover between Thermally Assisted and Pure Quantum Tunneling

Magnetization measurements of a truly axial symmetry Mn12-tBuAc molecular nanomagnet with a spin ground state of S = 10 show resonance tunneling. This compound has the same magnetic anisotropy as Mn12-Ac but the molecules are better isolated and the crystals have less disorder and a higher symmetry. Hysteresis loop measurements at several temperatures reveal a well-resolved step fine-structure which is due to level crossings of excited states. All step positions can be modeled by a simple spin Hamiltonian. The crossover between thermally assisted and pure quantum tunneling can be investigated with unprecedented detail.Comment: 5 pages, 6 figure

Referencing within code in software engineering education

Traditionally, computer sciences courses will assess software code. It is common and accepted good practice (as in written reports) to reference other sources of appropriate material. However there appears to be no explicit method, recommendation or advice available to computer science tutors and students on a referencing approach! This paper aims to stimulate discussion from peers involved in software engineering education. By discussing the apparent lack of ‘referencing within code’ advice to students and proposing suggestions for appropriate solutions. This will be based on the authors’ experience of assessing code and the current advice given to their students

Anomaly mediated neutrino-photon interactions at finite baryon density

We propose new physical processes based on the axial vector anomaly and described by the Wess-Zumino-Witten term that couples the photon, Z-boson, and the omega-meson. The interaction takes the form of a pseudo-Chern-Simons term, $\sim \epsilon_{\mu\nu\rho\sigma}\omega^\mu Z^\nu F^{\rho\sigma}$. This term induces neutrino-photon interactions at finite baryon density via the coupling of the Z-boson to neutrinos. These interactions may be detectable in various laboratory and astrophysical arenas. The new interactions may account for the MiniBooNE excess. They also produce a competitive contribution to neutron star cooling at temperatures >10^9 K. These processes and related axion--photon interactions at finite baryon density appear to be relevant in many astrophysical regimes.Comment: 4 pages, 2 figures; references adde

Variation in actual relationship among descendants of inbred individuals

In previous analyses, the variation in actual, or realized, relationship has been derived as a function of map length of chromosomes and type of relationship, the variation being greater the shorter the total chromosome length and the coefficient of variation being greater the more distant the relationship. Here, the results are extended to allow for the relatives' ancestor being inbred. Inbreeding of a parent reduces variation in actual relationship among its offspring, by an amount that depends on the inbreeding level and the type of mating that led to that level. For descendants of full-sibs, the variation is reduced in later generations, but for descendants of half-sibs, it is increased