Catalysis and evolution on cycling of nano-structured magnesium multilayer thin films

This paper explores the hydrogen cycling properties of Mg/Cr and Mg/V multilayer thin films and studies the effect of chromium and vanadium transition metal catalysts on the cycling properties of thick magnesium coatings. Two transition-metal catalysed magnesium-based multilayer PVD coatings are compared with a non-catalysed magnesium control sample. The (micro-)structural evolution of the thin film coatings into fine, flakey powders is studied in depth using XRD, SEM and TEM and the hydrogen storage properties of all three materials are assessed using volumetric, gravimetric and calorimetric methods focussing on the effect of the microstructure and composition of the coatings on the hydrogen storage kinetics. It was found that the chromiumcatalysed coating had the most favourable hydrogen storage kinetics with an activation energy for the dehydrogenation reaction of 65.7±2.5 kJ mol-1 and a hydrogen capacity of 6.1±0.3 wt%. The mechanism of the dehydrogenation reaction of the catalysed samples was studied using the CV and JMAK kinetic models and it was found that the catalyst material influenced not only the hydrogen storage kinetics but also the mechanism of the reaction

Relationship Between Muscle Strength, Power and Stiffness and Running Economy in Trained Male Runners

Purpose: In this study, a comparison was made between muscle strength, power and muscle and tendon (k(m), and k(t) respectively) stiffness of the triceps surae muscle group and running economy (RE) in trained male runners. Methods: Twelve well-trained male runners (age = 21 +/- 2.7 y, height = 178.1 +/- 7.1 cm, body mass = 66.7 +/- 3.2 kg, VO(2)max = 68.3 +/- 4.3 mL.kg(-1).min(-1), 5000-m time = 15:04 min:s) undement passive stiffness testing using a free oscillation method. Muscle strength was determined via a maximal isometric squat test and power determined via a maximal countermovement jump (CMJ). On a separate day, subjects performed an incremental treadmill test and their RE, lactate threshold, and VO(2)max were determined. Fingertip blood lactate was determined at the end of each 3-min stage. Lactate threshold was defined as a nonlinear increase in lactate accumulation. Results: A statistically significant correlation was found between k(m) and VO(2) at stage 6 (r = 0.69, P = .01). In addition, statistically significant correlations were observed between CMJ peak force production and VO(2) at stage 2 (r = .66, P = .02), stage 3 (r = .70, P = .01), and stage 4 (r = .58, P = .04). No other statistically significant correlations were observed. Conclusion: These data suggest that greater muscle stiffness and less power are associated with greater RE. Future study in this area should focus on determining the mechanisms behind this relationship and how to best apply them to a running population through training techniques

Ordering block copolymers

A method for ordering block copolymers including forming a first layer having a first preference mode; and providing a reactive agent in selected regions of the first layer that modifies the selected regions to a second preference mode, wherein the selected regions define other regions of the first layer retaining the first preference mode thereby forming an alignment layer for block copolymers.Board of Regents, University of Texas Syste

Shifts in dominant tree mycorrhizal associations in response to anthropogenic impacts

Plant-fungal symbioses play critical roles in vegetation dynamics and nutrient cycling, modulating the impacts of global changes on ecosystem functioning. Here, we used forest inventory data consisting of more than 3 million trees to develop a spatially resolved “mycorrhizal tree map” of the contiguous United States. We show that abundances of the two dominant mycorrhizal tree groups—arbuscular mycorrhizal (AM) and ectomycorrhizal trees—are associated primarily with climate. Further, we show that anthropogenic influences, primarily nitrogen (N) deposition and fire suppression, in concert with climate change, have increased AM tree dominance during the past three decades in the eastern United States. Given that most AM-dominated forests in this region are underlain by soils with high N availability, our results suggest that the increasing abundance of AM trees has the potential to induce nutrient acceleration, with critical consequences for forest productivity, ecosystem carbon and nutrient retention, and feedbacks to climate change

Are Eastern Oysters Being Bored to Death? Influence of \u3cem\u3eCliona celata\u3c/em\u3e on \u3cem\u3eCrassostrea virginica\u3c/em\u3e Condition, Growth and Survival

The boring sponge Cliona celata is a nuisance species that can have deleterious effects on eastern oyster Crassostrea virginica growth, condition, and survival. Surprisingly, however, these effects have not been well documented and when examined, results have been equi-vocal. In this study, we provide a direct comparison of growth, condition, and survival of sponge-colonized and uncolonized oysters in southeast North Carolina in 2 separate experiments. In the first experiment, sponge-colonized oysters exhibited significantly slower growth rates, reduced condition, and lower survival relative to uncolonized oysters, although results may have been confounded by oyster source. In the second experiment, using smaller oysters from the same source population, growth rate was again significantly reduced in colonized oysters relative to uncolonized oysters, however neither condition nor survival differed. In field surveys of the same population, colonized individuals across a range of sizes demonstrated significantly reduced condition. Further, condition index was negatively correlated with sponge biomass, which was positively correlated with oyster size, suggesting that the impact of the sponge changes with ontogeny. By investigating clearance rates, tissue isotopic and nutrient content, as well as caloric value, this study provides further evidence that sponge presence causes the oysters to divert energy into costly shell maintenance and repair at the expense of shell and somatic growth. Thus, although variable, our results demonstrate negative impacts of sponge infestation on oyster demographics, particularly as oysters grow larger

Oncolytic Virotherapy for Hematological Malignancies

Hematological malignancies such as leukemias, lymphomas, multiple myeloma (MM), and the myelodysplastic syndromes (MDSs) primarily affect adults and are difficult to treat. For high-risk disease, hematopoietic stem cell transplant (HCT) can be used. However, in the setting of autologous HCT, relapse due to contamination of the autograft with cancer cells remains a major challenge. Ex vivo manipulations of the autograft to purge cancer cells using chemotherapies and toxins have been attempted. Because these past strategies lack specificity for malignant cells and often impair the normal hematopoietic stem and progenitor cells, prior efforts to ex vivo purge autografts have resulted in prolonged cytopenias and graft failure. The ideal ex vivo purging agent would selectively target the contaminating cancer cells while spare normal stem and progenitor cells and would be applied quickly without toxicities to the recipient. One agent which meets these criteria is oncolytic viruses. This paper details experimental progress with reovirus, myxoma virus, measles virus, vesicular stomatitis virus, coxsackievirus, and vaccinia virus as well as requirements for translation of these results to the clinic

Refined forest land use classification with implications for United States national carbon accounting

The United States provides annual estimates of carbon sources and sinks as part of its National Green-house Gas Inventory (NGHGI). Within this effort, carbon stocks and fluxes are reported for six land use categories that are relevant to economic sectors and land use policy. The goal of this study is to develop methodologies that will allow the US to align with an internationally agreed upon forest land use definition which requires forest to be able to reach 5 m in height at maturity. Models to assess height potential are available for a majority of US forests except for woodland ecosystems. We develop a set of models to assess height potential in these systems. Our results suggest that ∼13.5 million ha of forests are unlikely to meet the international definition of forests due to environmental limitations to maximum attainable height. The incorporation of this height criteria in the NGHGI results in a carbon stock transfer of ∼848 Tg from the forest land use to woodland land use (a sub-category of grasslands) with minimal effect on sequestration rates. The development of a forest land use definition sensitive to climatic factors in this study enables a land use classification system that can be responsive to climate change effects on land uses themselves while being more consistent across a host of international and domestic carbon reporting efforts

Structure, stability, and reorganization of 0.5 L0 topography in block copolymer thin films

The structure, stability, and reorganization of lamella-forming block copolymer thin film surface topography (“islands” and “holes”) were studied under boundary conditions driving the formation of 0.5 L0 thick structures at short thermal annealing times. Self-consistent field theory predicts that the presence of one perfectly neutral surface renders 0.5 L0 topography thermodynamically stable relative to 1 L0 thick features, in agreement with previous experimental observations. The calculated through-film structures match cross-sectional scanning electron micrographs, collectively demonstrating the pinning of edge dislocations at the neutral surface. Remarkably, near-neutral surface compositions exhibit 0.5 L0 topography metastability upon extended thermal treatment, slowly transitioning to 1 L0 islands or holes as evidenced by optical and atomic force microscopy. Surface restructuring is rationalized by invoking commensurability effects imposed by slightly preferential surfaces. The results described herein clarify the impact of interfacial interactions on block copolymer self-assembly and solidify an understanding of 0.5 L0 topography, which is frequently used to determine neutral surface compositions of considerable importance to contemporary technological applications

Anhydride copolymer top coats for orientation control of thin film block copolymers

The concepts described herein involve the use of random copolymer top coats that can be spin coated onto block copolymer thin films and used to control the interfacial energy of the top coat-block copolymer interface. The top coats are soluble in aqueous weak base and can change surface energy once they are deposited onto the block copolymer thin film. The use of self-assembled block copolymers to produce advanced lithographic patterns relies on their orientation control in thin films. Top coats potentially allow for the facile orientation control of block copolymers which would otherwise be quite challenging.Board of Regents, University of Texas Syste