Environmental exposure effects on composite materials for commercial aircraft

A study was conducted to determine the effects of long term flight and ground exposure on three commercially available graphite-epoxy material systems: T300/5208, T300/5209, and T300/934. Sets of specimens were exposed on commercial aircraft and ground racks for 1, 2, 3, 5, and 10 years. Inflight specimen sites included both the interior and exterior of aircraft based in Hawaii, Texas, and New Zealand. Ground racks were located at NASA-Dryden and the above mentioned states. Similar specimens were exposed to controlled lab conditions for up to 2 years. After each exposure, specimens were tested for residual strength and a dryout procedure was used to measure moisture content. Both room and high temperature residual strengths were measured and expressed as a pct. of the unexposed strength. Lab exposures included the effects of time alone, moisture, time on moist specimens, weatherometer, and simulated ground-air-ground cycling. Residual strengths of the long term specimens were compared with residual strengths of the lab specimens. Strength retention depended on the exposure condition and the material system. Results showed that composite materials can be successfully used on commercial aircraft if environmental effects are considered

A note on monopole moduli spaces

We discuss the structure of the framed moduli space of Bogomolny monopoles for arbitrary symmetry breaking and extend the definition of its stratification to the case of arbitrary compact Lie groups. We show that each stratum is a union of submanifolds for which we conjecture that the natural $L^2$ metric is hyperKahler. The dimensions of the strata and of these submanifolds are calculated, and it is found that for the latter, the dimension is always a multiple of four.Comment: 17 pages, LaTe

Inversion symmetric 3-monopoles and the Atiyah-Hitchin manifold

We consider 3-monopoles symmetric under inversion symmetry. We show that the moduli space of these monopoles is an Atiyah-Hitchin submanifold of the 3-monopole moduli space. This allows what is known about 2-monopole dynamics to be translated into results about the dynamics of 3-monopoles. Using a numerical ADHMN construction we compute the monopole energy density at various points on two interesting geodesics. The first is a geodesic over the two-dimensional rounded cone submanifold corresponding to right angle scattering and the second is a closed geodesic for three orbiting monopoles.Comment: latex, 22 pages, 2 figures. To appear in Nonlinearit

Elucidating the electrochemical activity of electrolyte-insoluble polysulfide species in lithium-sulfur batteries

The direct synthesis of Li2 S2 , a proposed solid intermediate in the discharge of lithium-sulfur (Li-S) batteries, was accomplished by treating elemental lithium with sulfur in liquid ammonia at -41?? C. The as-synthesized product was analyzed by X-ray photoelectron spectroscopy (XPS) as well as X-ray diffraction (XRD) and determined to be a mixture of crystalline Li2 S, amorphous Li2 S2, and higher-order polysulfides (Li2 Sx , x > 2). Monitored filtration followed by a tailored electrochemical approach was used to successfully remove the higher-order polysulfides and yielded a powder, which was determined by XPS to be comprised of 9 mol% insoluble polysulfide species (mainly Li2 S2 ) and 91 mol% Li2 S. This material was discharged galvanostatically in an electrochemical cell and, despite the lack of soluble polysulfide species, was shown to exhibit a discharge plateau at 2.1 V vs. Li/Li+ . This result confirmed the electrochemical reducibility of electrolyte-insoluble polysulfides in Li-S batteries. Moreover, it was determined that the reduction of solid polysulfides was confined to areas where the sulfur-sulfur bonds were in intimate contact with the conductive current collector. Finally, it was observed that commercially available Li2 S samples contain significant quantities of polysulfide-type impurities.ope

Liquid Hydrogen Pressurization Tests Final Test Report, 29 May 1963 - 27 Aug. 1964

Liquid hydrogen pressurization tests for application to heat exchanger design in Saturn missil

129. Zaburzenia liczby kopii genów erbB-1 i erbB-2 i ich związek z danymi klinicznymi u leczonych operacyjnie chorych na niedrobnokomórkowego raka płuca

Szlak sygnałowy nabłonkowego czynnika wzrostu (ang. epidermal growth factor, EGF) i jego receptory (najważniejsze z nich to erbB-1 i erbB-2) odgrywają ważną rolę w patogenezie i progresji raka płuca. Kliniczne znaczenie nadekspresji tych receptorów pozostaje nadal przedmiotem kontrowersji a dotychczasowe badania przynosiły sprzeczne wyniki. Z uwagi na opracowane ostatnio leki o wybiórczym działaniu przeciwnowotworowym, działające poprzez powyższe receptory, poznanie rokowniczego znaczenia tych zaburzeń może odegrać ważną rolę w ustalaniu optymalnego sposobu leczenia. Celem pracy była ocena rokowniczego znaczenia anomalii średniej liczby kopii genów (ang. avarage gene copy numer, AGCN) u chorych na niedrobnokomórkowego raka płuca poddanych resekcji miąższu płucnego.Materiał i metodyDo badania włączono 112 chorych leczonych operacyjnie w latach 1996–1999. U 61 chorych (55%) rozpoznano postać raka płaskonabłonkowego, u 30 (27%) gruczolakoraka, u 10 (9%) raka wielokomórkowego i u 10 (9%) chorych postacie mieszane. Stopień zaawansowania nowotworu kształtował się następująco: I=54 (48%), II=11 (10%), III=40 (36%), IV=7 (6%). Materiał do analizy molekularnej stanowiło DNA izolowane ze świeżo mrożonych wycinków guza pobranych podczas zabiegu operacyjnego. AGCN określano za pomocą podwójnie różnicowej reakcji polimerazy i elektroforezy agarozowej.WynikiŚrednia wartość AGCN dla erbB-1 wynosiła 2,0 (zakres od 0,01 do 28,07), a dla erbB-2 1,34 (zakres od 0,11 do 9,9). Stwierdzono znamienną zależność pomiędzy AGCN dla obu genów. Nie stwierdzono znamiennego związku z jakimkolwiek głównym parametrem klinicznym. Do czasu przeprowadzenia analizy zmarło 73 chorych (65%). Po czasie obserwacji o medianie 5,1 roku nie stwierdzono wpływu AGCN na czas przeżycia (log-rank, P=0,9; 0,83; 0,8 odpowiednio dla erbB-1, erbB-2 i dla obu genów łącznie).WnioskiUzyskane wyniki wskazują na brak rokowniczego znaczenia AGCN erbB-1 i erbB-2 u chorych na raka płuca poddanych resekcji miąższu płucnego

Lipidomic profiling in Crohn's disease: abnormalities in phosphatidylinositols, with preservation of ceramide, phosphatidylcholine and phosphatidylserine composition.

Crohn's disease is a chronic inflammatory condition largely affecting the terminal ileum and large bowel. A contributing cause is the failure of an adequate acute inflammatory response as a result of impaired secretion of pro-inflammatory cytokines by macrophages. This defective secretion arises from aberrant vesicle trafficking, misdirecting the cytokines to lysosomal degradation. Aberrant intestinal permeability is also well-established in Crohn's disease. Both the disordered vesicle trafficking and increased bowel permeability could result from abnormal lipid composition. We thus measured the sphingo- and phospholipid composition of macrophages, using mass spectrometry and stable isotope labelling approaches. Stimulation of macrophages with heat-killed Escherichia coli resulted in three main changes; a significant reduction in the amount of individual ceramide species, an altered composition of phosphatidylcholine, and an increased rate of phosphatidylcholine synthesis in macrophages. These changes were observed in macrophages from both healthy control individuals and patients with Crohn's disease. The only difference detected between control and Crohn's disease macrophages was a reduced proportion of newly-synthesised phosphatidylinositol 16:0/18:1 over a defined time period. Shotgun lipidomics analysis of macroscopically non-inflamed ileal biopsies showed a significant decrease in this same lipid species with overall preservation of sphingolipid, phospholipid and cholesterol composition

New hyper-Kaehler manifolds by fixing monopoles

The construction of new hyper-Kaehler manifolds by taking the infinite monopole mass limit of certain Bogomol'nyi-Prasad-Sommerfield monopole moduli spaces is considered. The one-parameter family of hyperkaehler manifolds due to Dancer is shown to be an example of such manifolds. A new family of fixed monopole spaces is constructed. They are the moduli spaces of four SU(4) monopoles, in the infinite mass limit of two of the monopoles. These manifolds are shown to be nonsingular when the fixed monopole positions are distinct.Comment: Version in Phys. Rev. D. 11 pp, RevTeX, 14 Postscript diagram