Publications

Author(s): Alm, E.; Arkin, A.; Hazen, T.; Keasling, J.; Keller, M.; Mukhopadhyay, A.; Singh, A.; Stahl, D.; Thompson, D.; Wall, J.; Fields, M.; Zhou, J.

For composite materials applied for energy absorption and vibration/noise reduction, it is of particular significance to clarify the role of strain rate and temperature on their mechanical properties. Here we present a study on the effects of strain rate (from 10−3 s−1 to 1 s−1) and temperature (from room temperature to 350 °C) on the compressive properties of a 3-D printed Mg–NiTi interpenetrating-phase composite, which features high energy absorption efficiency and good damping capacity. Within the regimes of strain rate and temperature, the composite constantly exhibits a stable stress plateau on the stress-strain curves, yet displays markedly different damage mechanisms depending on the specific strain rate and temperature. The 3-D interpenetrating-phase architecture promotes an effective stress transfer in the composite and resists the propagation of local damages, thereby conferring a high strengthening efficiency and outstanding damage tolerance. The unique combination of mechanical properties makes the composite appealing for applications under various conditions, especially for absorbing mechanical energy and reducing vibrations and noise.

Alumina-based nanocomposites were fabricated and consolidated via spark plasma sintering. The effect of single-walled carbon nanotube (SWCNT) and niobium additions to nanocrystalline alumina was examined by in situ bend testing. The addition of 10vol.% niobium to nanocrystalline alumina provided substantial improvement of fracture toughness (6.1MPam1/2)—almost three times that of nanocrystalline alumina. Observation of cracks emanating from Vickers indents, as well as bend specimen fracture surfaces, reveal the operation of ductile phase toughening in the Nb–Al2O3 nanocomposites. Further addition of 5vol.% SWCNTs to the 10vol.%Nb–Al2O3 revealed a more porous structure and less impressive fracture toughness—having an indentation and bend fracture toughness of 2.9MPam1/2 and 3.3MPam1/2, respectively.

Water vapor sorption data and nitrogen sorption data for MOF-303 synthesized by solvothermal, reflux, vessel and microwave method.

ClinicalTrials.gov (Identifier: NCT02508129 ; Date Registered: July 21, 2015).

Mechanical surface treatments are known to be effective at improving the fatigue resistance of metallic alloys at elevated temperatures ({approx}550-600 C), even though the near-surface compressive residual stress fields have been annealed out. We have investigated the thermal stability of near-surface microstructures induced by deep rolling and laser-shock peening in an austentic stainless steel (AISI 304) and a titanium alloy (Ti-6Al-4V) using in situ hot-stage transmission electron microscopy. It is found that the improvements in fatigue resistance at elevated temperature are related to the high-temperature stability of the work-hardened near-surface microstructure in each case.

We report a supramolecular porous organic cage platform composed of cobalt porphyrins for catalyzing the electrochemical hydrogen evolution reaction (HER) from water at neutral pH. Owing to its permanent porosity, the supramolecular structure yields a catalyst film with a 5-fold increase in the number of electrochemically active cobalt atoms and an improvement in Tafel slope from 170 mV/decade to 119 mV/decade compared to a planar cobalt porphyrin analog, reaching activities over 19,000 turnovers for HER over a 24-hour period with 100% Faradaic efficiency.

Previous studies have indicated that the diversity of gamma genes expressed by gamma/delta-bearing murine T cells is limited, but comparable information concerning the expressed diversity of delta genes is lacking. In this study, we have investigated the rearrangement and expression of delta and gamma genes in T cell hybridomas that express gamma/delta T cell receptors. Three productive delta chain cDNA clones were isolated (delta 7.3, delta 7.1, and delta 2.3) that encode new variable region sequences. Two of the delta cDNAs differ significantly from those observed in the V alpha repertoire. In addition, one cDNA expressed a new J delta region (J delta 2), which was localized between J delta 1 and C delta genes. Using these and other delta gene probes and gamma gene probes, we found that five independent hybridomas expressed four different V delta s and three different V gamma s. However, analysis of an enriched population of gamma/delta-expressing cells from the adult thymus suggests that only a few V delta genes and one V gamma gene are used by the majority of the cells. These results suggest that important components of receptor chain that contribute to specificity (i.e., the germline V gene sequences) are relatively nondiverse in the thymic gamma/delta population.

In article number 1400915, Ivano E. Castelli and co-workers present a calculation of the bandgaps of 2400 experimentally known materials. The data for the bandgaps, which are shown as coming out of the open box in the image, are freely available in the Materials Project database and the Computational Materials Repository. They can be used as a descriptor to identify novel materials for one-photon water splitting in a photo-electrochemical cell. Cover illustration design by Kåre Wedel Jacobsen.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.