Despite extensive study of intestinal microbiome diversity and the role diet type in structuring gut microbial communities, we know very little about short-term changes as a result feeding alone. Sampling microbiomes over cycle will allow us to differentiate opportunistic, feeding-responsive microbes from resident, potentially commensal members community. Also, since has potential alter structure, sampling at different points relative last event likely yield conclusions composition function....

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPalladium-catalyzed additions of amines to conjugated dienes. Alteration behavior triphenylphosphine-palladium catalysts with amine hydroiodide saltsRobert W. Armbruster, Michael M. Morgan, James L. Schmidt, Chun Man Lau, Rose Riley, Daniel Zabrowsky, and Harold A. DieckCite this: Organometallics 1986, 5, 2, 234–237Publication Date (Print):February 1, 1986Publication History Published online1 May 2002Published inissue 1 February...

Overconstrained assemblies such as aircraft sub-assemblies present a challenge to production planners, variations in parts and processes can make it difficult achieve all assembly Key Characteristics (KCs) simultaneously. Despite assigning tight tolerances sub-component manufacture, part variation propagation necessitates expensive time-consuming management shimming order ensure the final is within specification. This paper presents for first time model overconstrained assemblies, develops...

Abstract The crystal structures of four thioxanthenium bis(carbomethoxy)methylides and methylides di‐( p ‐nitro‐phenyl)sulfonium dimethylsulfonium have been determined. carbanion moiety in all cases is planar the pi‐system rotated 90° with respect to sulfur lone pair. All compounds exhibit a pseudo‐equatorial orientation system except for 2,4‐dimethylthioxanthenium ylide. are described terms geometries around atom, interplanar angles sulfur‐oxygen oxygen‐oxygen interactions. Surprisingly,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic effects in the reaction of carbonyl oxides with aldehydesRobert W. Murray and Michael M. MorganCite this: J. Org. Chem. 1991, 56, 2, 684–687Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/jo00002a036https://doi.org/10.1021/jo00002a036research-articleACS PublicationsRequest reuse permissionsArticle Views288Altmetric-Citations13LEARN...

Elastic-plastic crack front fields in arc-shaped tension specimens (C-specimens) were analyzed by a three-dimensional finite element method. The effect of side grooves on the ductile fracture behavior was investigated studying J-integral distribution, plane-strain constraint parameter, and development plastic zones comparing to experimental data. applicability η factor (derived for use with compact specimens) calculation values C-specimen also investigated. results show that promote...

The effect of hydrogen on the fracture toughness properties Types 304L, 316L and 21-6-9 forged stainless steels was investigated. Fracture samples were fabricated from forward-extruded forgings. Samples uniformly saturated with after exposure to gas at 34 MPa or 69 623 K prior testing. characterized by measuring J-R behavior ambient temperature in air. results show that hydrogen-charged have values about 50–60% measured for unexposed steels. reduction accompanied a change appearance. Both...

J-Integral fracture toughness tests were conducted on tritium-exposed-and-aged Types 304L and 21-6-9 stainless steel weldments in order to measure the combined effects of tritium its decay product, helium-3 properties. Initially, have values about three times higher than base-metal values. Delta-ferrite phase weld microstructure improved provided no was present microstructure. After a tritium-exposure-and-aging treatment that resulted ~1400 atomic parts per million (appm) dissolved tritium,...

Crack extensions in arc-shaped specimens of hydrogen-charged and as-received conventionally forged (CF) 21-6-9 austenitic stainless steels are investigated by two-dimensional finite element analyses with the cohesive zone model. The material constitutive relation is first obtained from fitting experimental tensile stress-strain data conducting an axisymmetric analysis a round bar specimen CF steel. for steel estimated based on high-energy-rate-forged (HERF) model exponential...

Abstract The single‐crystal X‐ray structures of 9‐hydroxy‐1,4‐dimethylthioxanthenium bis(carbomethoxy)methylide and 1,4‐oxathianium are reported. methylide carbon the former is pseudo‐axial while that latter equatorial. exhibits a strong intramolecular hydrogen bond to carbonyl oxygen atom.

The long-term embrittlement effects of tritium and decay helium on the structural properties stainless steels have been studied for years at Savannah River National Laboratory (Savannah River) to provide required data establishing safe operating conditions lifetimes pressure vessels used contain gas. In this study, fracture toughness longest-aged tritium-precharged steel base metals weldments tested were measured compared earlier results. values lowest recorded here tritium-exposed steel....

Abstract The synthesis of 1, 4, 9‐triazaphenoxathiin and the analysis two‐dimensional J‐resolved (2DJ) 1 H‐nmr spectra molecule at 100 200 MHz are reported. Due to strong coupling ABX AB spin systems, additional resonances observed in 2DJ spectrum which diminished intensity shifted further from F = O Hz case system MHz, or have disappeared system. Calculated frequencies intensities due were found be excellent agreement with data.

Burst testing is used to assess the performance of stainless steel pressure vessels designed contain tritium, a radioactive isotope hydrogen. ductility tritium-exposed reduced in time as result combined embrittlement effects from tritium that has diffused into microstructure and its decay product, helium-3. A materials system model finite element procedure were developed predict burst vessel volume change (ductility) during testing. The changes service history, known values diffusivity,...