Failure mechanisms of graphene under tension

Recent experiments established pure graphene as the strongest material known to mankind, further invigorating the question of how graphene fails. Using density functional theory, we reveal the mechanisms of mechanical failure of pure graphene under a generic state of tension. One failure mechanism is a novel soft-mode phonon instability of the $K_1$-mode, whereby the graphene sheet undergoes a phase transition and is driven towards isolated benzene rings resulting in a reduction of strength. The other is the usual elastic instability corresponding to a maximum in the stress-strain curve. Our results indicate that finite wave vector soft modes can be the key factor in limiting the strength of monolayer materials

Effect of Soil Washing on Petroleum-Hydrocarbon Distribution on Sand Surfaces

A soil washing study was performed to evaluate the treatability of New River sand contaminated in the laboratory with a petroleum distillate. Unaltered and base-extracted sands were mixed with petroleum hydrocarbons, equilibrated, and washed with water or a surfactant at two different pH values (7 and 12). The surfactant had no significant effect on contaminant removal efficiencies at neutral pH. Treatment efficiencies of baseextracted sand particles were 10 to 13% higher than for the unaltered sands. Scanning electron microscopy (SEM) with elemental X-ray microprobe was used to determine the distribution of iron and carbon on the New River sand surface. Qualitative interpretations of the SEM/X-ray photomicrographs disclosed that iron oxides were associated with organic carbon on the sand surfaces, with sulfur believed to be a constituent of the petroleum contamination. Low petroleum removal efficiencies for New River sand observed in previous studies were believed to be influenced by the high iron oxide content of the sand and the affinity of these metal oxides to bind natural and petroleum-derived organic carbon

Path integral Monte Carlo simulations of silicates

We investigate the thermal expansion of crystalline SiO$_2$ in the $\beta$-- cristobalite and the $\beta$-quartz structure with path integral Monte Carlo (PIMC) techniques. This simulation method allows to treat low-temperature quantum effects properly. At temperatures below the Debye temperature, thermal properties obtained with PIMC agree better with experimental results than those obtained with classical Monte Carlo methods.Comment: 27 pages, 10 figures, Phys. Rev. B (in press

Cloned defective interfering influenza virus protects ferrets from pandemic 2009 influenza A virus and allows protective immunity to be established

Influenza A viruses are a major cause of morbidity and mortality in the human population, causing epidemics in the winter, and occasional worldwide pandemics. In addition there are periodic outbreaks in domestic poultry, horses, pigs, dogs, and cats. Infections of domestic birds can be fatal for the birds and their human contacts. Control in man operates through vaccines and antivirals, but both have their limitations. In the search for an alternative treatment we have focussed on defective interfering (DI) influenza A virus. Such a DI virus is superficially indistinguishable from a normal virus but has a large deletion in one of the eight RNAs that make up the viral genome. Antiviral activity resides in the deleted RNA. We have cloned one such highly active DI RNA derived from segment 1 (244 DI virus) and shown earlier that intranasal administration protects mice from lethal disease caused by a number of different influenza A viruses. A more cogent model of human influenza is the ferret. Here we found that intranasal treatment with a single dose of 2 or 0.2 µg 244 RNA delivered as A/PR/8/34 virus particles protected ferrets from disease caused by pandemic virus A/California/04/09 (A/Cal; H1N1). Specifically, 244 DI virus significantly reduced fever, weight loss, respiratory symptoms, and infectious load. 244 DI RNA, the active principle, was amplified in nasal washes following infection with A/Cal, consistent with its amelioration of clinical disease. Animals that were treated with 244 DI RNA cleared infectious and DI viruses without delay. Despite the attenuation of infection and disease by DI virus, ferrets formed high levels of A/Cal-specific serum haemagglutination-inhibiting antibodies and were solidly immune to rechallenge with A/Cal. Together with earlier data from mouse studies, we conclude that 244 DI virus is a highly effective antiviral with activity potentially against all influenza A subtypes

Radar plots: A novel modality for displaying disparate data on the efficacy of eluxadoline for the treatment of irritable bowel syndrome with diarrhea

BackgroundPatients with irritable bowel syndrome with diarrhea (IBS‐D) experience a range of abdominal and bowel symptoms; successful management requires alleviation of this constellation of symptoms. Eluxadoline, a locally active mixed μ‐ and κ‐opioid receptor agonist and δ‐opioid receptor antagonist, is approved for the treatment of IBS‐D in adults based on the results of 2 Phase 3 studies. Radar plots can facilitate comprehensive, visual evaluation of diverse but interrelated efficacy endpoints.MethodsTwo double‐blind, placebo‐controlled, Phase 3 trials (IBS‐3001 and IBS‐3002) randomized patients meeting Rome III criteria for IBS‐D to twice‐daily eluxadoline 75 or 100 mg or placebo. Radar plots were prepared showing pooled Weeks 1‐26 response rates for the primary efficacy composite endpoint (simultaneous improvement in abdominal pain and stool consistency), stool consistency, abdominal pain, urgency‐free days, and adequate relief, and change from baseline to Week 26 in IBS‐D global symptom score, abdominal discomfort, abdominal pain, abdominal bloating, and daily number of bowel movements.Key ResultsThe studies enrolled 2428 patients. Eluxadoline increased Weeks 1‐26 responder proportions vs placebo for the composite endpoint, stool consistency, abdominal pain, urgency‐free days, and adequate relief. Changes from baseline to Week 26 in IBS‐D global symptom score, abdominal discomfort, abdominal pain, abdominal bloating, and number of bowel movements were greater with eluxadoline vs placebo.Conclusions and InferencesData presentation in radar plot format facilitates interpretation across multiple domains, demonstrating that eluxadoline treatment led to improvements vs placebo across 13 endpoints representing the range of symptoms experienced by patients with IBS‐D.Data presentation in radar plot format can facilitate evaluation of the diverse array of symptoms and outcomes that are relevant to a symptom‐based condition like irritable bowel syndrome with diarrhea (IBS‐D). In 2 Phase 3 trials, eluxadoline treatment improved stool consistency and frequency, abdominal pain, bloating and discomfort, feelings of urgency, global symptom score, and adequate relief. Radar plots provide a visual demonstration of improvements with eluxadoline across 13 endpoints encompassing the diverse constellation of symptoms experienced by patients with IBS‐D.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145265/1/nmo13331_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145265/2/nmo13331.pd

Shining a light on the composition and distribution patterns of mesophotic and subphotic fish communities in Hawai‘i

As agencies shift from single-species management to ecosystem-based fisheries management, ecosystem models are gaining interest for understanding species dynamics in relation to oceanographic and ecological processes and human marine uses. However, information on community structure or distribution of many species that occupy deep (>30 m) waters is largely unavailable. We amassed a total of 24 686 fish observations of 523 species/taxa for the 30−410 m depth areas surrounding the main Hawaiian Islands (MHI). We also obtained estimates of geomorphological variables, including substrate type, slope, rugosity, and ridge-like features. Using these 2 data sources, we (1) identified distinct fish communities along the 30−410 m depth gradient, and (2) generated relative biomass maps for fish functional groups. We showed that the mesophotic zone ranges between 30 and 129 m, with a fish faunal break at 60 m. Beyond this zone, 4 subphotic zones were identified: upper rariphotic (130−169 m), mid-rariphotic (170−239 m), lower rariphotic (240−319 m), and upper bathyal (320−410 m). We assigned fish species to functional groups partly based on identified depth ranges and fitted general additive models (GAMs) integrating geomorphological covariates to the functional group relative biomass estimates to determine the environmental variables that best predict the probability of encounter and relative biomass of each fish functional group. Finally, GAM predictions were employed to map functional group relative biomass distributions. These distribution maps showed a high relative biomass of many groups in the center of the MHI chain. This study contributes to a better understanding of fish community structure around the MHI and will inform ecosystem model parameterization

Phonon Band Structure and Thermal Transport Correlation in a Layered Diatomic Crystal

To elucidate the relationship between a crystal's structure, its thermal conductivity, and its phonon dispersion characteristics, an analysis is conducted on layered diatomic Lennard-Jones crystals with various mass ratios. Lattice dynamics theory and molecular dynamics simulations are used to predict the phonon dispersion curves and the thermal conductivity. The layered structure generates directionally dependent thermal conductivities lower than those predicted by density trends alone. The dispersion characteristics are quantified using a set of novel band diagram metrics, which are used to assess the contributions of acoustic phonons and optical phonons to the thermal conductivity. The thermal conductivity increases as the extent of the acoustic modes increases, and decreases as the extent of the stop bands increases. The sensitivity of the thermal conductivity to the band diagram metrics is highest at low temperatures, where there is less anharmonic scattering, indicating that dispersion plays a more prominent role in thermal transport in that regime. We propose that the dispersion metrics (i) provide an indirect measure of the relative contributions of dispersion and anharmonic scattering to the thermal transport, and (ii) uncouple the standard thermal conductivity structure-property relation to that of structure-dispersion and dispersion-property relations, providing opportunities for better understanding of the underlying physical mechanisms and a potential tool for material design.Comment: 30 pages, 10 figure

Predicting sexual problems in women: The relevance of sexual excitation and sexual inhibition

This is the post-print version of the article. The official published version can be obtained from the link below.Data from a non-clinical sample of 540 heterosexual women were used to examine the relationships between scores on the Sexual Excitation/Sexual Inhibition Inventory for Women (SESII-W) and ratings of current sexual problems, lifetime arousal difficulty, lifetime orgasm difficulty, and lifetime problems with low sexual interest. Multiple regression analyses also included several demographic/background variables as predictors: age, full-time employment, completed college, children in household, married, health ratings, importance of sex, and whether the woman was in a sexual relationship. The strongest statistical predictors of both current and lifetime sexual problems were the SESII-W inhibition factors Arousal Contingency and Concerns about Sexual Function. Demographic factors did not feature largely in any of the models predicting sexual problems even when statistically significant relationships were found. If future research supports the predictive utility of the SESII-W in identifying women who are more likely to experience sexual difficulties, these scales may be used as prognostic factors in treatment studies.This study was funded, in part, by a grant from the Lilly Centre for Women's Health

A competitive polymerase chain reaction-based approach for the identification and semiquantification of mitochondrial DNA in differently heat-treated bovine meat and bone meal

The risk of bovine spongiform encephalopathy propagation was drastically reduced after the European Union (EU) Health Authorities adopted restrictions involving a ban on animal-derived proteins in the diet of farm animals. Currently, the EU's officially recommended method for controlling meat and bone meal (MBM) in animal feed is the microscopic method, which involves the identification of bone fragments on the basis of their morphological characteristics. Recently, we demonstrated that a polymerase chain reaction (PCR)-based assay can be used for the detection of taxon-specific DNA in MBM and animal feeds. To ensure the safe rendering of animal by-products, the EU Council requires that this material be treated at 133degreesC at 300 kPa for 20 min. Here we investigate the relationship between DNA degradation, PCR amplification, and MBM heat treatment. With a competitive PCR-based approach, we compare the amplification efficiency of bovine mitochondrial DNA target sequences of different lengths in several heat-treated MBM samples. For our method, a synthetic competitive DNA is used as an internal control for both DNA extraction and PCR reaction. A correlation between an increase in treatment temperature and a reduction in the size of the target sequences suitable for amplification was observed, suggesting progressive DNA fragmentation due to the temperature. We show that short amplicons (147 bp) can be used to detect the presence of bovine mtDNA in MBM samples treated according to the current European regulations. The use of such a competitive approach to compare amplification efficiency levels of targets of different lengths might represent a useful tool for the determination of both the amount of MBM in animal feeds and its proper heat treatment