Publications

Cathodes with high energy density and safety are sought to improve the performance of Li ion batteries for electric vehicle and consumer electronics applications. In this study, we examine the properties of the potential new cathodes Li(subscript 9)M(subscript 3)(P(subscript 2)O(subscript 7))(subscript 3)(PO(subscript 4))(subscript 2) for M = V, Mo with density functional theory calculations. These compounds emerged as potentially interesting cathodes from a high-throughput computational search. In this work, we investigate computationally the voltage, volume change, stability, safety, and diffusivity of Li(subscript x)V(subscript 3)(P(subscript 2)O(subscript 7))(subscript 3)(PO(subscript 4))(subscript 2) and find that extracting the final Li in this material will be difficult due to voltage and safety concerns. We suggest the yet-unreported class of compounds Li(subscript x)V(subscript 3)−(subscript 3y)M(subscript o3y)(P(subscript 2)O(subscript 7))(subscript 3)(PO(subscript 4))(subscript 2) as a potential improvement over the pure V compound. In particular, our computations indicate that y = 2/3 deserves further computational and experimental attention.

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.

We present CCD photometry and low-resolution spectra of the spectroscopic Type Ic supernova SN 1983V in NGC 1365. Photometry in the B band spans nearly 250 days after maximum light, while the spectra cover the photospheric epoch, from 9 days before up to 38 days after B maximum. We also compile and discuss infrared photometry that has been published elsewhere. The photometric evolution of SN 1983V is analyzed in comparison with other Type Ic supernovae and with SN 1983N and SN 1993J. The spectroscopic evolution is described, line identifications are proposed, and evidence for H, He, and Si is discussed. The photometric evolution of SN 1983V suggests that it is a close relative of SN 1983N and SN 1993J, events for which it is supposed that the external layers comprising most of the He/H and H shells, respectively, were lost before the explosion. The mass-to-energy ratios of SN 1983V and SN 1993J are substantially different if estimated from the expansion velocities. However, the similarity of the B light curves suggests that if the masses and mass-to-energy ratios are not similar, then the mass of SN 1983V has to be large enough to compensate for the higher mass-to-energy ratio. The latter possibility contradicts the standard scenarios that describe these events and implies a precise fine-tuning of the masses and mass-to-energy ratios of the two supernovae. This contradiction, however, could be resolved if a significant fraction of the inner ejecta containing 56Ni does not follow the decrease in density expected for a spherically symmetric, homologous expansion.

Compatibility and stability issues in all-solid-state batteries and methods for investigation.

There is now a significant and growing functional gap between the public Internet, whose basic architecture has remained unchanged for several decades, and a new generation of more sophisticated private networks. To address this increasing divergence of functionality and overcome the Internet's architectural stagnation, we argue for the creation of an Extensible Internet (EI) that supports in-network services that go beyond best-effort packet delivery. To gain experience with this approach, we hope to soon deploy both an experimental version (for researchers) and a prototype version (for early adopters) of EI. In the longer term, making the Internet extensible will require a community to initiate and oversee the effort; this paper is the first step in creating such a community.

The work at U. C. Berkeley was supported by the Miller Institute for Basic Research in Science as well as NSF grant AST 94-17213. Supernova research at Harvard University is supported by the NSF through grants AST 95-28899 and AST 92-18475.

Background: Although reward processing is considered an important part of affective functioning, few studies have investigated reward‐related decisions or responses in young people with affective disorders. Depression is postulated to involve decreased activity in reward‐related affective systems. Methods: Using functional magnetic resonance imaging (fMRI), we examined behavioral and neural responses to reward in young people with depressive disorders using a reward decision‐making task. The task involved choices about possible rewards involving varying magnitude and probability of reward. The study design allowed the separation of decision/anticipation and outcome phases of reward processing. Participants were 9–17 years old and had diagnoses of major depressive disorder (MDD), anxiety disorders, or no history of psychiatric disorder. Results: Participants with MDD exhibited less neural response than control participants in reward‐related brain areas during both phases of the task. Group differences did not appear to be a function of anxiety. Depressive and anxiety symptoms were associated with activation in reward‐related brain areas. Conclusions: Results suggest that depression involves altered reward processing and underscore the need for further investigation of relations among development, affective disorders, and reward processing.

Nanoparticles with a tendency to phase separate interact with each other during a process of either intraparticle phase separation (occurring inside the particle) or interparticle phase separation (occurring between particles). In this paper, we examine a halfcell consisting of two particles to systematically analyze the particle interactions and their resulting voltage response at different insertion currents. The kinetics of the interactions between nanoparticles is studied for cases in which particles undergo interparticle and intraparticle phase separation. Our results indicate that the interactions between particles in a cell containing only particles that undergo intraparticle phase separation are similar to those in a cell containing only particles that undergo interparticle phase separation. In both cases, sequential transformation occurs at low currents, whereas a simultaneous transformation occurs at high currents. Furthermore, such transformation dynamics changes in cases where the cell contains a mixture of particles that undergo interparticle and intraparticle phase separations, which exhibits more complex dynamics.

ABSTRACT Producing complex chemicals using synthetic metabolic pathways in microbial hosts can have many advantages over chemical synthesis but is often complicated by deleterious interactions between pathway intermediates and the host cell metabolism. With the maturation of functional genomic analysis, it is now technically feasible to identify modes of toxicity associated with the accumulation of foreign molecules in the engineered bacterium. Previously, Escherichia coli was engineered to produce large quantities of isoprenoids by creating a mevalonate-based isopentenyl pyrophosphate biosynthetic pathway (V. J. J. Martin et al., Nat. Biotechnol. 21: 796-802, 2003). The engineered E. coli strain produced high levels of isoprenoids, but further optimization led to an imbalance in carbon flux and the accumulation of the pathway intermediate 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA), which proved to be cytotoxic to E. coli . Using both DNA microarray analysis and targeted metabolite profiling, we have studied E. coli strains inhibited by the intracellular accumulation of HMG-CoA. Our results indicate that HMG-CoA inhibits fatty acid biosynthesis in the microbial host, leading to generalized membrane stress. The cytotoxic effects of HMG-CoA accumulation can be counteracted by the addition of palmitic acid (16:0) and, to a lesser extent, oleic acid ( cis -Δ 9 -18:1) in the growth medium. This work demonstrates the utility of using transcriptomic and metabolomic methods to optimize synthetic biological systems.