Metastable crystalline AuGe catalysts formed during isothermal germanium nanowire growth.

We observe the formation of metastable AuGe phases without quenching, during strictly isothermal nucleation and growth of Ge nanowires, using video-rate lattice-resolved environmental transmission electron microscopy. We explain the unexpected formation of these phases through a novel pathway involving changes in composition rather than temperature. The metastable catalyst has important implications for nanowire growth, and more broadly, the isothermal process provides both a new approach to growing and studying metastable phases, and a new perspective on their formation.A. D. G. acknowledges funding from the Marshall Aid Commemoration Commission and the National Science Foundation. S. H. and C. D. acknowledge funding from the Royal Society. S. H. acknowledges funding from ERC grant InsituNANO (n°279342).This is the accepted manuscript. The final version is available from APS at http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.108.255702

Twin plane re-entrant mechanism for catalytic nanowire growth.

A twin-plane based nanowire growth mechanism is established using Au catalyzed Ge nanowire growth as a model system. Video-rate lattice-resolved environmental transmission electron microscopy shows a convex, V-shaped liquid catalyst-nanowire growth interface for a ⟨112⟩ growth direction that is composed of two Ge {111} planes that meet at a twin boundary. Unlike bulk crystals, the nanowire geometry allows steady-state growth with a single twin boundary at the nanowire center. We suggest that the nucleation barrier at the twin-plane re-entrant groove is effectively reduced by the line energy, and hence the twin acts as a preferential nucleation site that dictates the lateral step flow cycle which constitutes nanowire growth.S. H. acknowledges funding from ERC grant InsituNANO (project number 279342). A. D. G. acknowledges funding from the Marshall Aid Commemoration Commission and the National Science Foundation. C. D. acknowledge funding from the Royal Society. P.V. acknowledges the support of ONR grant N00014-12-1-0198. We gratefully acknowledge the use of facilities within the LeRoy Eyring Center for Solid State Science at Arizona State University.This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/nl404244u. (AD Gamalski, PW Voorhees, C Ducati, R Sharma, S Hofmann, Nano Letters 2014, 14, 1288–1292

An Olympic Joke: Sanctioning the Olympic Movement

Article published in the Michigan State International Law Review

An evaluation of health research methodology in the literature

Understanding the research being conducted in health care is essential to being an effective manager. Using databases such as Medline and Pub Med, provided by the National Institute of Health, and selecting the criteria of keywords health , management , research and trial , published since 2002 in English and on human subjects, a population of peer-reviewed journals was identified. A random sample from this population was obtained; the research methodologies were evaluated and compared for practical application

The phase of iron catalyst nanoparticles during carbon nanotube growth

We study the Fe-catalyzed chemical vapor deposition of carbon nanotubes by complementary in situ grazing-incidence X-ray diffraction, in situ X-ray reflectivity, and environmental transmission electron microscopy. We find that typical oxide supported Fe catalyst films form widely varying mixtures of bcc and fcc phased Fe nanoparticles upon reduction, which we ascribe to variations in minor commonly present carbon contamination levels. Depending on the as-formed phase composition, different growth modes occur upon hydrocarbon exposure: For γ-rich Fe nanoparticle distributions, metallic Fe is the active catalyst phase, implying that carbide formation is not a prerequisite for nanotube growth. For α-rich catalyst mixtures, Fe3C formation more readily occurs and constitutes part of the nanotube growth process. We propose that this behavior can be rationalized in terms of kinetically accessible pathways, which we discuss in the context of the bulk iron–carbon phase diagram with the inclusion of phase equilibrium lines for metastable Fe3C. Our results indicate that kinetic effects dominate the complex catalyst phase evolution during realistic CNT growth recipes.S.H. acknowledges funding from ERC grant InsituNANO (No. 279342). We acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation facilities. We acknowledge the use of facilities within the LeRoy Eyring Center for Solid State Science at Arizona State University. C.T.W. and C.S.E. acknowledge funding from the EC project Technotubes. A.D.G. acknowledges funding from the Marshall Aid Commemoration Commission and the National Science Foundation. R.S.W. acknowledges funding from EPSRC (Doctoral training award) and B.C.B. acknowledges a Research Fellowship at Hughes Hall, Cambridge.This is the accepted manuscript. The final version is available from ACS at http://pubs.acs.org/doi/abs/10.1021/cm301402g

Catalyst composition and impurity-dependent kinetics of nanowire heteroepitaxy.

The mechanisms and kinetics of axial Ge-Si nanowire heteroepitaxial growth based on the tailoring of the Au catalyst composition via Ga alloying are studied by environmental transmission electron microscopy combined with systematic ex situ CVD calibrations. The morphology of the Ge-Si heterojunction, in particular, the extent of a local, asymmetric increase in nanowire diameter, is found to depend on the Ga composition of the catalyst, on the TMGa precursor exposure temperature, and on the presence of dopants. To rationalize the findings, a general nucleation-based model for nanowire heteroepitaxy is established which is anticipated to be relevant to a wide range of material systems and device-enabling heterostructures.S.H. acknowledges funding from ERC grant InsituNANO (No. 279342). A.D.G. acknowledges funding from the Marshall Aid Commemoration Commission and the National Science Foundation. C.D. acknowledges funding from the Royal Society. A portion of the research was also performed using EMSL, a national scientific user facility sponsored by the Department of Energy’s (DOE) Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the U.S. DOE under Contract DE-AC05-76RL01830. We gratefully acknowledge the use of facilities within the LeRoy Eyring Center for Solid State Science at Arizona State University. This work was performed in part at CINT, a U.S. DOE, Office of Science User Facility. The research was funded in part by the Laboratory Directed Research and Development Program at LANL, an affirmative action equal opportunity employer operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the U.S. DOE under Contract DE-AC52-06NA25396.This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/nn402208p. Gamalski AD, Perea DE, Yoo J, Li N, Olszta MJ, Colby R, Schreiber DK, Ducati C, Picraux ST, Hofmann S, ACS Nano 2013, 7 (9), 7689–7697, doi:10.1021/nn402208

Spotlight on Direct Cash Benefits during the Pandemic

As the country looks to emerge from the pandemic during a destabilized labor market, a debate has arisen over whether direct cash payments discourage people from working. This debate echoes long-standing ideological disputes over the social safety net, including the effectiveness and appropriateness of direct cash benefits, and whether people will spend them wisely. The existing quantitative data demonstrates that the Coronavirus Aid, Relief, and Economic Security (CARES) Act, including its direct cash benefit provisions, helped many people avert material hardship, while for those who were ineligible, its absence exacerbated hardship.Previous Poverty Tracker reports have shown that nearly half (49%) of all New York City workers lost employment income at the height of the COVID-19 pandemic. And those hardest-hit were those already in precarious financial positions, with more than half (57%) of low-wage workers in New York City losing employment income. Across the city, New Yorkers were forced to figure out how to pay rent and keep food on the table with no sense of what was to come next. To make ends meet, 52% of New Yorkers who lost employment income drew down from their savings accounts, 41% started using their credit cards more frequently, and 29% delayed payments on credit cards and other loans. But the data also show that it could have been much worse absent policy interventions, such as the stimulus checks and expanded unemployment insurance benefits (UIB) that so many New Yorkers describe as a lifeline in the qualitative interviews discussed in the pages that follow.In this report, we draw on qualitative data from the Poverty Tracker to better understand how these benefits impacted peoples' lives and the choices they made. We conducted a rolling set of interviews with 38 adults in New York City from July 2020 through May 2021. With some exceptions, we interviewed people twice at roughly six-month intervals. Our research design therefore allows us to track people's experiences with successive waves of stimulus payments and UIB, their spending of these benefits, and their efforts to return to work (or not) over time. We first describe how people budgeted and apportioned these benefits. We next examine whether and how direct cash benefits affected decision-making about employment

Surface Crystallization of Liquid Au-Si and Its Impact on Catalysis.

In situ transmission electron microscopy reveals that an atomically thin crystalline phase at the surface of liquid Au-Si is stable over an unexpectedly wide range of conditions. By measuring the surface structure as a function of liquid temperature and composition, a simple thermodynamic model is developed to explain the stability of the ordered phase. The presence of surface ordering plays a key role in the pathway by which the Au-Si eutectic solidifies and also dramatically affects the catalytic properties of the liquid, explaining the anomalously slow growth kinetics of Si nanowires at low temperature. A strategy to control the presence of the surface phase is discussed, using it as a tool in designing strategies for nanostructure growth

In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper.

Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, on the Cu surface during exposure to borazine. A Cu lattice expansion during borazine exposure and B precipitation from Cu upon cooling highlight that B is incorporated into the Cu bulk, i.e., that growth is not just surface-mediated. On this basis we suggest that B is taken up in the Cu catalyst while N is not (by relative amounts), indicating element-specific feeding mechanisms including the bulk of the catalyst. We further show that oxygen intercalation readily occurs under as-grown h-BN during ambient air exposure, as is common in further processing, and that this negatively affects the stability of h-BN on the catalyst. For extended air exposure Cu oxidation is observed, and upon re-heating in vacuum an oxygen-mediated disintegration of the h-BN film via volatile boron oxides occurs. Importantly, this disintegration is catalyst mediated, i.e., occurs at the catalyst/h-BN interface and depends on the level of oxygen fed to this interface. In turn, however, deliberate feeding of oxygen during h-BN deposition can positively affect control over film morphology. We discuss the implications of these observations in the context of corrosion protection and relate them to challenges in process integration and heterostructure CVD.P.R.K. acknowledges funding from the Cambridge Commonwealth Trust and the Lindemann Trust Fellowship. R.S.W. acknowledges a research fellowship from St. John’s College, Cambridge. S.H. acknowledges funding from ERC grant InsituNANO (no. 279342), EPSRC under grant GRAPHTED (project reference EP/K016636/1), Grant EP/H047565/1 and EU FP7 Work Programme under grant GRAFOL (project reference 285275). The European Synchrotron Radiation Facility (ESRF) is acknowledged for provision of synchrotron radiation and assistance in using beamline BM20/ROBL. We acknowledge Helmholtz-Zentrum-Berlin Electron storage ring BESSY II for synchrotron radiation at the ISISS beamline and continuous support of our experiments.This is the final version. It was first published by ACS at http://pubs.acs.org/doi/abs/10.1021/cm502603

Cistercian Canonical Observance

iii, 65 p.Numerous monastic traditions have come down through the ages to modern Western society. From the early Desert Fathers there was the simple yet deep spirit of devotion to the Diety. Their lives in the wilderness of Asia Minor inspired many imitators and followers. Out of this early tradition grew the first monastic communities. The cenobites, monks in communities, as opposed to anchorite hermits, set up rules and laws to guide their lives. One of the most successful of these Rules was that of St. Benedict. It is from the followers of his rule that the great community of Benedictines has grown. The Benedictine family has sent out many branches and roots in the form of various Orders. All of them subscribe to the same Rule but there are many different interpretations of that document. Chief among them since the middle of the Middle Ages has been the Cistercian Order. In an examination of this Order an attempt will be made to show how the Rule has been applied to the Divine Office. The work of the Divine Office is the vocation which in essence is the core of Western monastic observance. The Cistercian interpretation of the obligations of this office through the years will hopefully show how one group has interpreted this flexible document, and how it has shaped the "Office " obligations of the Order. In working toward this end the Divine Office will be examined as it is presented by Benedict in his Rule. This will show how the earliest Cistercians fulfilled their obligations according to the Rule's tenets. After the establishment of this early scheme some of the Cistercian safeguards for maintaining uniformity in the Divine Office will be examined as well as additions to duties that the Cistercians made. Finally an attempt will be made to establish the obligations of modern era Cistercians to the Rule as it applies to the Divine Office. It will become apparent in the examination of the facets of the Cistercian interpretation how they, like all of their predecessors, must continually struggle to maintain the purity and consistency of their interpretation through the centuries since their founding in the wilderness of medieval Burgundy