Stable Heteronuclear Few-Atom Bound States in Mixed Dimensions

We study few-body problems in mixed dimensions with $N \ge 2$ heavy atoms trapped individually in parallel one-dimensional tubes or two-dimensional disks, and a single light atom travels freely in three dimensions. By using the Born-Oppenheimer approximation, we find three- and four-body bound states for a broad region of heavy-light atom scattering length combinations. Specifically, the existence of trimer and tetramer states persist to negative scattering lengths regime, where no two-body bound state is present. These few-body bound states are analogous to the Efimov states in three dimensions, but are stable against three-body recombination due to geometric separation. In addition, we find that the binding energy of the ground trimer and tetramer state reaches its maximum value when the scattering lengths are comparable to the separation between the low-dimensional traps. This resonant behavior is a unique feature for the few-body bound states in mixed dimensions.Comment: Extended version with 14 pages and 14 figure

E1-Like Activating Enzyme Atg7 Is Preferentially Sequestered into p62 Aggregates via Its Interaction with LC3-I

p62 is constitutively degraded by autophagy via its interaction with LC3. However, the interaction of p62 with LC3 species in the context of the LC3 lipidation process is not specified. Further, the p62-mediated protein aggregation's effect on autophagy is unclear. We systemically analyzed the interactions of p62 with all known Atg proteins involved in LC3 lipidation. We find that p62 does not interact with LC3 at the stages when it is being processed by Atg4B or when it is complexed or conjugated with Atg3. p62 does interact with LC3-I and LC3-I:Atg7 complex and is preferentially recruited by LC3-II species under autophagic stimulation. Given that Atg4B, Atg3 and LC3-Atg3 are indispensable for LC3-II conversion, our study reveals a protective mechanism for Atg4B, Atg3 and LC3-Atg3 conjugate from being inappropriately sequestered into p62 aggregates. Our findings imply that p62 could potentially impair autophagy by negatively affecting LC3 lipidation and contribute to the development of protein aggregate diseases. © 2013 Gao et al

Carbon and Nitrogen Pools in Soil Aggregates Were Affected by Grazing Component ---- Results from Dry and Wet Sieving Methods

Grazing intensity can affect soil carbon (C) sequestration in semiarid grassland, but less is known about the effects of grazing component (defoliation, trampling, excreta return and their combinations) on the C and Nitrogen (N) in soil aggregates. In this study, a simulated grazing experiment was established in a typical steppe of Inner Mongolia, and we investigated the impacts of different grazing component treatments on the different size of aggregates distribution and their C and N content from dry and wet physical separations. Different soil C fractions were showed in different sieving method. The C content of different aggregate size showed microaggregates (250-53μm, 7-17%)\u3emacroaggregates (\u3e250μm, 4-12%) \u3efine fraction (\u3c53μm, 0.4-3%) when dry sieving method was performed, but wet sieving resulted in the higher C content in microaggregates (6-14%) and fine fraction (5-11%) than macroaggregates (1-5%). N content of different size of aggregates showed similar trend with C content. The results revealed that grazing component had a marked impact on soil fraction and C and N content with the significant decreasing percentage of macroaggregates and their C and N storage under defoliation. Our result indicated that both dry-sieved aggregates and water-stable aggregates should be concerned to evaluate the short-term grazing disturbance on C and N distribution in soil aggregates. Furthermore, we suggest that trampling is critical for the soil compaction, but defoliation may play a more important role in soil aggregation and C storage in grazing grassland

Preliminary Change Request for including chromaticity sextupoles in the SNS accumulator ring

In view of the adopted design changes for SNS accumulator ring [1], complementary studies have been undertaken, in order to justify the need of high-field chromatic sextupoles for chromaticity correction