Electric field Induced Patterns in Soft Visco-elastic films: From Long Waves of Viscous Liquids to Short Waves of Elastic Solids

We show that the electric field driven surface instability of visco-elastic films has two distinct regimes: (1) The visco-elastic films behaving like a liquid display long wavelengths governed by applied voltage and surface tension, independent of its elastic storage and viscous loss moduli, and (2) the films behaving like a solid require a threshold voltage for the instability whose wavelength always scales as ~ 4 x film thickness, independent of its surface tension, applied voltage, loss and storage moduli. Wavelength in a narrow transition zone between these regimes depends on the storage modulus.Comment: Accepted for Publication in Physical Review Letter

Understanding Strain‐Induced Phase Transformations in BiFeO3 Thin Films

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113160/1/advs201500041.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/113160/2/advs201500041-sup-0001-S1.pd

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

Thin Films: Understanding Strain‐Induced Phase Transformations in BiFeO3 Thin Films (Adv. Sci. 8/2015)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113104/1/advs201570029.pd

Correlating Local Structure with Electrochemical Activity in Li₂MnO₃

Li₂MnO₃ is believed to be a critical component of the high capacity Li-rich–manganese-rich oxide materials; however, the mechanism of its electrochemical activity remains controversial. Here, Raman spectroscopy and mapping are used to follow the chemical and structural changes that occur in Li₂MnO₃ during electrochemical cycling. Conventional composite electrodes cast from a slurry and thin films are studied as a function of the state of charge (voltage) and cycle number. Thin films have similar electrochemical properties as electrodes prepared from slurries but enable spectroscopy of uniform samples without carbon additives and binder. First-principles density functional theory is used to calculate the phonon spectra and identify the Raman-active modes. On the basis of the calculations of phonon spectra for pristine Li₂MnO₃ and structures with Li vacancies, we discuss the origin of Raman-active peaks observed during the electrochemical cycling. The spectral changes correlate well with the electrochemical behavior and support a mechanism whereby capacity is lost upon extended cycling due to the formation of new manganese oxide phases