bluuebunny/crossref_metadata_2025 huggingface dataset:
The nature and processes of market co-creation in triple bottom line firms: Leveraging insights from consumer culture theory and service dominant logic
Authors: Peñaloza Lisa , Mish Jenny
Published: April 2011

This paper contributes theoretical and practical understandings regarding market co-creation by cross-fertilizing insights from consumer culture theory (CCT) on the production of meaning with service-dominant logic (SDL) on the co-creation of value. Examining nine firms acting to achieve environmental, social, and economic sustainability, we suggest that cultural meanings are an important part of the value elaborated in SDL, and conversely that such value informs the meanings emphasized in CCT. Findings demonstrate three levels of meaning and value negotiated by multiple actors in markets: cosmological principles, norms and standards, and individual judgments and interpretations. Discussion deciphers key overlaps and distinctions between meaning and value, operand and operant resources, and economic, social and environmental domains as they converge in market co-creation. Contributions theorize asymmetries of value and meaning in the intricate interweaving of social and market domains characterizing contemporary market co-creation. We close with practical implications for consumers, firms, and public policy.
The diagnostic accuracy of X-ray arthrography for triangular fibrocartilaginous complex injury: a systematic review and meta-analysis
Authors: Smith T. O. , Drew B. T. , Toms A. P. , Chojnowski A. J.
Published: April 2011

The purpose of this study was to evaluate the diagnostic test accuracy of X-ray arthrography in the detection of TFCC tear. Both published and unpublished databases were searched from their inception to August 2010. All studies comparing the diagnostic accuracy of X-ray arthrography (index test) to arthroscopy (reference standard) for patients with suspected TFCC tears were included in this review. Twelve studies assessing 430 patients (430 wrists) satisfied the eligibility criteria and were included. X-ray arthrography presented with a pooled sensitivity of 76.2% and specificity of 92.5% for the detection of complete TFCC tear. The triple-compartment injection X-ray arthrography was superior to the single-compartment injection technique. To conclude, the diagnostic test accuracy of X-ray arthrography is limited. Neither the single- nor the triple-compartment injection arthrography method is acceptable, given their reported low sensitivities. Further evaluation of the diagnostic test accuracy of Magnetic Resonance Arthrography and Magnetic Resonance Imaging is therefore warranted.
Developing Mechanisms of Self-Regulation in Early Life
Authors: Rothbart Mary K. , Sheese Brad E. , Rueda M. Rosario , Posner Michael I.
Published: April 2011

Children show increasing control of emotions and behavior during their early years. Our studies suggest a shift in control from the brain’s orienting network in infancy to the executive network by the age of 3—4 years. Our longitudinal study indicates that orienting influences both positive and negative affect, as measured by parent report in infancy. At 3—4 years of age, the dominant control of affect rests in a frontal brain network that involves the anterior cingulate gyrus. Connectivity of brain structures also changes from infancy to toddlerhood. Early connectivity of parietal and frontal areas is important in orienting; later connectivity involves midfrontal and anterior cingulate areas related to executive attention and self-regulation.
Differentiation, Dynamical Integration and Functional Emotional Development
Authors: Camras Linda A.
Published: April 2011

In recent decades, considerable progress has been made in our understanding of emotional development. Yet no single current theory can fully encompass all of the empirical findings. Herein I propose that aspects of several theoretical approaches can be incorporated into a novel view that is informed by the dynamical systems perspective.
Current Emotion Research in Organizational Behavior
Authors: Ashkanasy Neal M. , Humphrey Ronald H.
Published: April 2011

Despite a long period of neglect, research on emotion in organizational behavior has developed into a major field over the past 15 years, and is now seen to be part of an affective revolution in the organization sciences. In this article, we review current research on emotion in the organizational behavior field based on five levels of analysis: within person, between persons, dyadic interactions, leadership and teams, and organization-wide. Specific topics we cover include affective events theory, state and trait affect and mood, emotional intelligence, emotional labor, emotional contagion, emotions and leadership, and building a healthy emotional climate. We conclude with suggestions for future research.
Using context to improve protein domain identification
Authors: Ochoa Alejandro , Llinás Manuel , Singh Mona
Published: April 2011

Background

Identifying domains in protein sequences is an important step in protein structural and functional annotation. Existing domain recognition methods typically evaluate each domain prediction independently of the rest. However, the majority of proteins are multidomain, and pairwise domain co-occurrences are highly specific and non-transitive.

Results

Here, we demonstrate how to exploit domain co-occurrence to boost weak domain predictions that appear in previously observed combinations, while penalizing higher confidence domains if such combinations have never been observed. Our framework, Domain Prediction Using Context (dPUC), incorporates pairwise "context" scores between domains, along with traditional domain scores and thresholds, and improves domain prediction across a variety of organisms from bacteria to protozoa and metazoa. Among the genomes we tested, dPUC is most successful at improving predictions for the poorly-annotated malaria parasite Plasmodium falciparum, for which over 38% of the genome is currently unannotated. Our approach enables high-confidence annotations in this organism and the identification of orthologs to many core machinery proteins conserved in all eukaryotes, including those involved in ribosomal assembly and other RNA processing events, which surprisingly had not been previously known.

Conclusions

Overall, our results demonstrate that this new context-based approach will provide significant improvements in domain and function prediction, especially for poorly understood genomes for which the need for additional annotations is greatest. Source code for the algorithm is available under a GPL open source license at http://compbio.cs.princeton.edu/dpuc/. Pre-computed results for our test organisms and a web server are also available at that location.
Reliability analysis of the Ahringer Caenorhabditis elegans RNAi feeding library: a guide for genome-wide screens
Authors: Qu Wubin , Ren Changhong , Li Yuan , Shi Jinping , Zhang Jiye , Wang Xiaolei , Hang Xingyi , Lu Yiming , Zhao Dongsheng , Zhang Chenggang
Published: April 2011

Background

The Ahringer C. elegans RNAi feeding library prepared by cloning genomic DNA fragments has been widely used in genome-wide analysis of gene function. However, the library has not been thoroughly validated by direct sequencing, and there are potential errors, including: 1) mis-annotation (the clone with the retired gene name should be remapped to the actual target gene); 2) nonspecific PCR amplification; 3) cross-RNAi; 4) mis-operation such as sample loading error, etc.

Results

Here we performed a reliability analysis on the Ahringer C. elegans RNAi feeding library, which contains 16,256 bacterial strains, using a bioinformatics approach. Results demonstrated that most (98.3%) of the bacterial strains in the library are reliable. However, we also found that 2,851 (17.54%) bacterial strains need to be re-annotated even they are reliable. Most of these bacterial strains are the clones having the retired gene names. Besides, 28 strains are grouped into unreliable category and 226 strains are marginal because of probably expressing unrelated double-stranded RNAs (dsRNAs). The accuracy of the prediction was further confirmed by direct sequencing analysis of 496 bacterial strains. Finally, a freely accessible database named CelRNAi (http://biocompute.bmi.ac.cn/CelRNAi/) was developed as a valuable complement resource for the feeding RNAi library by providing the predicted information on all bacterial strains. Moreover, submission of the direct sequencing result or any other annotations for the bacterial strains to the database are allowed and will be integrated into the CelRNAi database to improve the accuracy of the library. In addition, we provide five candidate primer sets for each of the unreliable and marginal bacterial strains for users to construct an alternative vector for their own RNAi studies.

Conclusions

Because of the potential unreliability of the Ahringer C. elegans RNAi feeding library, we strongly suggest the user examine the reliability information of the bacterial strains in the CelRNAi database before performing RNAi experiments, as well as the post-RNAi experiment analysis.
Identification and characterisation of seed storage protein transcripts from Lupinus angustifolius
Authors: Foley Rhonda C , Gao Ling-Ling , Spriggs Andrew , Soo Lena YC , Goggin Danica E , Smith Penelope MC , Atkins Craig A , Singh Karam B
Published: April 2011

Background

In legumes, seed storage proteins are important for the developing seedling and are an important source of protein for humans and animals. Lupinus angustifolius (L.), also known as narrow-leaf lupin (NLL) is a grain legume crop that is gaining recognition as a potential human health food as the grain is high in protein and dietary fibre, gluten-free and low in fat and starch.

Results

Genes encoding the seed storage proteins of NLL were characterised by sequencing cDNA clones derived from developing seeds. Four families of seed storage proteins were identified and comprised three unique α, seven β, two γ and four δ conglutins. This study added eleven new expressed storage protein genes for the species. A comparison of the deduced amino acid sequences of NLL conglutins with those available for the storage proteins of Lupinus albus (L.), Pisum sativum (L.), Medicago truncatula (L.), Arachis hypogaea (L.) and Glycine max (L.) permitted the analysis of a phylogenetic relationships between proteins and demonstrated, in general, that the strongest conservation occurred within species. In the case of 7S globulin (β conglutins) and 2S sulphur-rich albumin (δ conglutins), the analysis suggests that gene duplication occurred after legume speciation. This contrasted with 11S globulin (α conglutin) and basic 7S (γ conglutin) sequences where some of these sequences appear to have diverged prior to speciation. The most abundant NLL conglutin family was β (56%), followed by α (24%), δ (15%) and γ (6%) and the transcript levels of these genes increased 103 to 106 fold during seed development. We used the 16 NLL conglutin sequences identified here to determine that for individuals specifically allergic to lupin, all seven members of the β conglutin family were potential allergens.

Conclusion

This study has characterised 16 seed storage protein genes in NLL including 11 newly-identified members. It has helped lay the foundation for efforts to use molecular breeding approaches to improve lupins, for example by reducing allergens or increasing the expression of specific seed storage protein(s) with desirable nutritional properties.
Wet chemical synthesis and magnetic properties of single crystal Co nanochains with surface amorphous passivation Co layers
Authors: Zhou Shao-Min , Lou Shi-Yun , Wang Yong-Qiang , Chen Xi-Liang , Liu Li-Sheng , Yuan Hong-Lei
Published: April 2011

In this study, for the first time, high-yield chain-like one-dimensional (1D) Co nanostructures without any impurity have been produced by means of a solution dispersion approach under permanent-magnet. Size, morphology, component, and structure of the as-made samples have been confirmed by several techniques, and nanochains (NCs) with diameter of approximately 60 nm consisting of single-crystalline Co and amorphous Co-capped layer (about 3 nm) have been materialized. The as-synthesized Co samples do not include any other adulterants. The high-quality NC growth mechanism is proposed to be driven by magnetostatic interaction because NC can be reorganized under a weak magnetic field. Room-temperature-enhanced coercivity of NCs was observed, which is considered to have potential applications in spin filtering, high density magnetic recording, and nanosensors.

PACS: 61.46.Df; 75.50; 81.07.Vb; 81.07.
Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater
Authors: Uchida Tsutomu , Oshita Seiichi , Ohmori Masayuki , Tsuno Takuo , Soejima Koichi , Shinozaki Satoshi , Take Yasuhisa , Mitsuda Koichi
Published: April 2011

Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM) with the freeze-fractured replica method to observe oxygen (O2) MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface.

PACS: 68.03.-g, 81.07.-b, 92.40.qc
Effectiveness of injectable risperidone long-acting therapy for schizophrenia: data from the US, Spain, Australia, and Belgium
Authors: Lambert Tim , Olivares José M , Peuskens Joseph , DeSouza Cherilyn , Kozma Chris M , Otten Patrick , Crivera Concetta , Jacobs An , Macfadden Wayne , Mao Lian , Rodriguez Stephen C , Dirani Riad , Akhras Kasem S
Published: April 2011

Background

Because wide variations in mental health care utilization exist throughout the world, determining long-term effectiveness of psychotropic medications in a real-world setting would be beneficial to physicians and patients. The purpose of this analysis was to describe the effectiveness of injectable risperidone long-acting therapy (RLAT) for schizophrenia across countries.

Methods

This was a pragmatic analysis of data from two prospective observational studies conducted in the US (Schizophrenia Outcomes Utilization Relapse and Clinical Evaluation [SOURCE]; ClinicalTrials.gov registration number for the SOURCE study: NCT00246194) and Spain, Australia, and Belgium (electronic Schizophrenia Treatment Adherence Registry [eSTAR]). Two separate analyses were performed to assess clinical improvement during the study and estimate psychiatric hospitalization rates before and after RLAT initiation. Clinical improvement was evaluated using the Clinical Global Impressions-Severity (CGI-S) and Global Assessment of Functioning (GAF) scales, and change from baseline was evaluated using paired t tests. Psychiatric hospitalization rates were analyzed using incidence densities, and the bootstrap resampling method was used to examine differences between the pre-baseline and post-baseline periods.

Results

The initial sample comprised 3,069 patients (US, n = 532; Spain, n = 1,345; Australia, n = 784; and Belgium, n = 408). In all, 24 months of study participation, completed by 39.3% (n = 209), 62.7% (n = 843), 45.8% (n = 359), and 64.2% (n = 262) of patients from the US, Spain, Australia, and Belgium, respectively, were included in the clinical analysis. Improvements compared with baseline were observed on both clinical assessments across countries (P < 0.001 at all post-baseline visits). The mean improvement was approximately 1 point on the CGI-S and 15 points on the GAF. A total of 435 (81.8%), 1,339 (99.6%), 734 (93.6%), and 393 (96.3%) patients from the US, Spain, Australia, and Belgium, respectively, had ≥1 post-baseline visit and were included in the analysis of psychiatric hospitalization rates. Hospitalization rates decreased significantly in all countries regardless of hospitalization status at RLAT initiation (P < 0.0001) and decreased significantly in the US and Spain (P < 0.0001) when the analysis was limited to outpatients only.

Conclusions

RLAT in patients with schizophrenia was associated with improvements in clinical and functional outcomes and decreased hospitalization rates in the US, Spain, Australia, and Belgium, despite differences in health care delivery systems.
Sequential generation of olfactory bulb glutamatergic neurons by Neurog2-expressing precursor cells
Authors: Winpenny Eleanor , Lebel-Potter Mélanie , Fernandez Maria E , Brill Monika S , Götz Magdalena , Guillemot Francois , Raineteau Olivier
Published: April 2011

Background

While the diversity and spatio-temporal origin of olfactory bulb (OB) GABAergic interneurons has been studied in detail, much less is known about the subtypes of glutamatergic OB interneurons.

Results

We studied the temporal generation and diversity of Neurog2-positive precursor progeny using an inducible genetic fate mapping approach. We show that all subtypes of glutamatergic neurons derive from Neurog2 positive progenitors during development of the OB. Projection neurons, that is, mitral and tufted cells, are produced at early embryonic stages, while a heterogeneous population of glutamatergic juxtaglomerular neurons are generated at later embryonic as well as at perinatal stages. While most juxtaglomerular neurons express the T-Box protein Tbr2, those generated later also express Tbr1. Based on morphological features, these juxtaglomerular cells can be identified as tufted interneurons and short axon cells, respectively. Finally, targeted electroporation experiments provide evidence that while the majority of OB glutamatergic neurons are generated from intrabulbar progenitors, a small portion of them originate from extrabulbar regions at perinatal ages.

Conclusions

We provide the first comprehensive analysis of the temporal and spatial generation of OB glutamatergic neurons and identify distinct populations of juxtaglomerular interneurons that differ in their antigenic properties and time of origin.
Targeted electroporation of defined lateral ventricular walls: a novel and rapid method to study fate specification during postnatal forebrain neurogenesis
Authors: Fernández María E , Croce Simona , Boutin Camille , Cremer Harold , Raineteau Olivier
Published: April 2011

Background

Postnatal olfactory bulb (OB) neurogenesis involves the generation of granule and periglomerular cells by neural stem cells (NSCs) located in the walls of the lateral ventricle (LV). Recent studies show that NSCs located in different regions of the LV give rise to different types of OB neurons. However, the molecular mechanisms governing neuronal specification remain largely unknown and new methods to approach these questions are needed.

Results

In this study, we refine electroporation of the postnatal forebrain as a technique to perform precise and accurate delivery of transgenes to NSCs located in distinct walls of the LV in the mouse. Using this method, we confirm and expand previous studies showing that NSCs in distinct walls of the LV produce neurons that invade different layers of the OB. Fate mapping of the progeny of radial glial cells located in these distinct LV walls reveals their specification into defined subtypes of granule and periglomerular neurons.

Conclusions

Our results provide a baseline with which future studies aiming at investigating the role of factors in postnatal forebrain neuronal specification can be compared. Targeted electroporation of defined LV NSC populations will prove valuable to study the genetic factors involved in forebrain neuronal specification.
A mutated xylose reductase increases bioethanol production more than a glucose/xylose facilitator in simultaneous fermentation and co-fermentation of wheat straw
Authors: Olofsson Kim , Runquist David , Hahn-Hägerdal Bärbel , Lidén Gunnar
Published: April 2011

Genetically engineered Saccharomyces cerevisiae strains are able to ferment xylose present in lignocellulosic biomass. However, better xylose fermenting strains are required to reach complete xylose uptake in simultaneous saccharification and co-fermentation (SSCF) of lignocellulosic hydrolyzates. In the current study, haploid Saccharomyces cerevisiae strains expressing a heterologous xylose pathway including either the native xylose reductase (XR) from P. stipiti s, a mutated variant of XR (mXR) with altered co-factor preference, a glucose/xylose facilitator (Gxf1) from Candida intermedia or both mXR and Gxf1 were assessed in SSCF of acid-pretreated non-detoxified wheat straw. The xylose conversion in SSCF was doubled with the S. cerevisiae strain expressing mXR compared to the isogenic strain expressing the native XR, converting 76% and 38%, respectively. The xylitol yield was less than half using mXR in comparison with the native variant. As a result of this, the ethanol yield increased from 0.33 to 0.39 g g-1 when the native XR was replaced by mXR. In contrast, the expression of Gxf1 only slightly increased the xylose uptake, and did not increase the ethanol production. The results suggest that ethanolic xylose fermentation under SSCF conditions is controlled primarily by the XR activity and to a much lesser extent by xylose transport.
Gold Sodium Thiomalate for the Treatment of Rheumatoid Arthritis in a Patient with Hepatitis B
Authors: Buckley Whitney A , Stump Amy L , Monger Robert M , Lookabill Sara K
Published: April 2011

Objective:

To describe a case of gold sodium thiomalate use for the treatment of rheumatoid arthritis (RA) in a patient with hepatitis B.

Case Summary:

A 53*year-old Korean American woman with mild RA and chronic hepatitis B infection was treated for worsening RA symptoms with subcutaneous injections of gold sodium thiomalate for 21 months, with the dosage decreased from the initial 40 mg per week to 40 mg every 3 weeks after 51 weeks of successful treatment. She had undergone treatment for hepatitis B in the past with lamivudine; however, she had not received that medication for at least 1 year prior to initiating treatment with gold sodium thiomalate injections. During the treatment period she achieved remission of RA without a significant elevation of her liver enzyme levels or reactivation of hepatitis B.

Discussion:

TWO main factors influence drug product selection when considering the subset of RA patients with chronic hepatitis B infection: severity of liver function compromise and treatment status of chronic hepatitis B. Our patient did not demonstrate significant liver function compromise, but was not receiving viral suppressive treatment for hepatitis B; therefore, the use of many first-line nonbiologic disease-modifying antirheumatic drugs (DMARDs) was contraindicated based on current guideline recommendations. Additionally, because the patient had refused viral suppressive therapy, there was great concern with the use of biological DMAFDs and potential reactivation of hepatitis B. In the past, gold salts were the standard of care in treating RA until the development of the newer agents and there was some evidence that gold sodium thiomalate could be used with minimal risk of hepatotoxicity.

Conclusions:

Gold sodium thiomalate proved to be a safe and effective treatment option in a patient with RA and hepatitis B.
Partial sequence of the DNA-dependent DNA polymerase gene of fowl adenoviruses: A reference panel for a general diagnostic PCR in poultry
Authors: Kaján Győző , Sameti Soroush , Benkő Mária
Published: April 2011

Adenoviruses are frequent infectious agents in different poultry species. The traditional, serological typing of new isolates by virus neutralisation tests is now in transition to be replaced by PCR and sequencing. The first PCRs, recommended for the detection of adenoviruses, had been designed to target the gene of the major capsid protein, the hexon. In birds, members of three different genera of the familyAdenoviridaemay occur. Accordingly, three specific hexon PCRs had to be elaborated for the detection of adenoviruses in poultry. A significantly more sensitive PCR, targeting the viral DNA-dependent DNA polymerase gene, has been described recently. This method proved to be an efficient alternative for the general detection of adenoviruses irrespective of their genus affiliation. Fowl adenoviruses (FAdVs), isolated from chicken to date, comprise twelve serotypes classified into five virus species (FAdV-A to E). The polymerase gene sequence has been determined yet only from three FAdV types representing three species. In the present work, the panel of polymerase gene sequences was completed with those of the rest of FAdVs. The newly determined sequences will facilitate the identification of new FAdV isolates as an existing species or as a putative new FAdV. Once the polymerase sequence is known, more specific PCRs for the amplification of the hexon and other genes can be designed and performed according to the preliminary species classification.
Application of Gd and Pd nanoparticles in a ‘new generation’ switchable mirror
Authors: Aruna I. , Mehta Bodh Raj , Malhotra Lalit Kumar
Published: April 2011

‘Nanoparticle route’ has been utilized to fabricate a ‘new generation’ of switchable mirrors in which the switching properties can be tuned by controlling the nanoparticle size in the underlying Gd layer or Pd over layer. Better color neutrality, faster response time, improved optical contrast, and an enhanced stability has been observed in Gd nanoparticle layer as a direct consequence of the size-induced blue shift in the optical band gap and enhanced surface area. The improvements in optical and electrical switching characteristics are directly related to the large change in H concentration during loading-deloading cycles in Gd nanoparticle layers. It has also been observed that a uniformly deposited Pd nanoparticle over layer also plays a crucial role for improving hydrogen recovery time.
Emission Quenching of a Poly(Phenylene Ethynylene) (PPE) in the Solid State
Authors: George Wayne N. , Steinke Joachim H. G. , de Mello John C. , Giles Mark , McCulloch Iain
Published: April 2011

The ability of a poly(phenylene ethynylene) conjugated polyelectrolyte to detect a small molecule quencher in the solid state was assessed by coating the polymer onto a plastic-backed, non-fluorescent, silica-gel TLC plate. The efficiency of the emission quenching process was quantified by noting the resulting loss of emission with increasing quencher concentration, in accordance with the Stern-Volmer relation. The emission quenching induced by the addition of the analyte occurred with Stern-Volmer constants in the range of 103 M−1.
State-of-the-Art Developments in the Field of Electroactive Polymers
Authors: Vinogradov Aleksandra , Su Ji , Jenkins Christopher , Bar-Cohen Yoseph
Published: April 2011

The paper presents a review in the field of electroactive polymers. It outlines the main classes of electroactive polymers, their properties and applications. Current efforts to synthesize electroactive polymers with novel or improved characteristics along with the challenges, opportunities and future research directions are discussed.
The Effect of Temperature Exposure on Polypyrrole Actuation
Authors: Cole Matthew , Madden John D.
Published: April 2011

Polypyrrole actuators offer attractive possibilities due to their large electrochemical stress (>5MPa), moderate to large strain (>2 %) and low voltage operation (<2 V). However, little is known about their temperature dependence response, with nearly all previous tests performed at room temperature. To test the effects of increasing temperature, polypyrrole films in water and propylene carbonate were thermally cycled twice from 22°C to 80°C. Length and actuation were measured before, after and between cycling. Results show that polypyrrole in TBAPF6(propylene carbonate) underwent a 4.8% irrecoverable contraction during the first cycle and lost half it’s actuation each cycle. Polypyrrole in NaPF6(aq) showed a 2.1% initial expansion in length on the first cycle followed by a 2.1% contraction on the next cycle, while active strain amplitude dropped from 7.7% to 5.9% to 4.9%. Polypyrrole in NaCl(aq) has a net contraction of 6% over two cycles with no significant change in it’s original 3.5% actuation amplitude. This suggests that although films in NaPF6(aq) have the best initial strain, films in NaCl(aq) maintain the most consistent strain amplitude in response to temperature on the timescales observed. Strain to charge ratio was found to decrease slightly, but the majority of the loss in actuation for films is correlated with a reduction in charge transfer each cycle. This reduction may result from a reduction in the active volume of film.
Introduction to First-Principles Electronic Structure Methods: Application to Actinide Materials
Authors: Klepeis John E
Published: April 2011

The purpose of this paper is to provide an introduction for non-experts to first-principles electronic structure methods that are widely used in the field of condensed-matter physics, including applications to actinide materials. The methods I describe are based on density functional theory (DFT) within the local density approximation (LDA) and the generalized gradient approximation (GGA). In addition to explaining the meaning of this terminology I also describe the underlying theory itself in some detail in order to enable a better understanding of the relative strengths and weaknesses of the methods. I briefly mention some particular numerical implementations of DFT, including the linear muffin-tin orbital (LMTO), linear augmented plane wave (LAPW), and pseudopotential methods, as well as general methodologies that go beyond DFT and specifically address some of the weaknesses of the theory. The last third of the paper is devoted to a few selected applications that illustrate the ideas discussed in the first two-thirds. In particular, I conclude by addressing the current controversy regarding magnetic DFT calculations for actinide materials. Throughout this paper particular emphasis is placed on providing the appropriate background to enable the non-expert to gain a better appreciation of the application of first-principles electronic structure methods to the study of actinide and other materials.
5f Delocalization of Bulk FCC Americium and the (111) Surface: A FP-LAPW Electronic Structure Study
Authors: Gao Da , Ray Asok K
Published: April 2011

The electronic properties of bulk fcc americium and the (111) surface have been investigated with the full-potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2K suite of programs The study is carried out for the anti-ferromagnetic ground state of Am at different levels of theory: (1) scalar-relativity vs. full-relativity; (2) local-density approximation (LDA) vs. generalized-gradient approximation (GGA). Our results indicate that spin orbit coupling plays an important role in determining the electronic properties of both bulk fcc americium and the (111) surface. In general, LDA is found to give a higher total energy compared to GGA results. The spin orbit coupling shows a similar effect on the surface calculations regardless of the model, GGA versus LDA. The 5f localized-delocalized transition of americium is employed to explain our results. In addition, the quantum size effects in the surface energies and the work functions of fcc (111) americium ultra thin films (UTF) are also examined.
Using Nano-focussed Bremstrahlung Isochromat Spectroscopy (nBIS) to Determine the Unoccupied Electronic Structure of Pu
Authors: Butterfield Martin , Tobin James , Teslich Nick , Bliss Annie , Wall Mark , McMahan Andy , Chung Brandon , Schwartz Adam , Kutepov A.L
Published: April 2011

The investigation of the actinides is of great interest because of their unique electronic structure. At the pivotal point of the behavior of the electronic structure of the actinide series is plutonium. Pu has the most complex phase diagram of all metals, both with regard to the intricacy of the crystal structures and the number of different phases. While there are a number of ongoing experimental efforts directed at determining the occupied electronic structure of Pu, there is essentially no experimental data on the unoccupied electronic structure of Pu. We aim to determine the conduction band (unoccupied) electronic structure of Pu and other actinides in a phase specific fashion and emphasizing bulk contributions by using Nano-focussed Bremstrahlung Isochromat Spectroscopy (nBIS). BIS is the high-energy variant of inverse photoelectron spectroscopy (IPES: electron in, photon out), which is essentially the time reversal of photoelectron spectroscopy (photon in, electron out). IPES can be used to follow the dispersion of electronic states in ordered samples. Owing to its low energies, IPES is usually very surface sensitive. However, by working at higher energies, we will sample preferentially for bulk properties, downgrading the impact of surface effects. Thus, from BIS, we would have a direct measure of the conduction band or unoccupied electronic structure of the bulk Pu. By using a nano-focused electron source associated with a SEM, we hope to gather phase specific information from crystallites within polycrystalline Pu samples. We will discuss the experimental arrangement required to carry out such an experiment and our progress in building such a system.
Spinodal ordering and precipitation in U-6wt%Nb
Authors: Hsiung Luke Lieh-Ming , Zhou Jikou
Published: April 2011

A combinative approach of microhardness testing, tensile testing, and TEM microstructural analysis was employed to study the microstructure and mechanical instability of a water-quenched U-6wt.% Nb (WQ-U6Nb) alloy subjected to different aging schedules including artificial aging at 200°C, 15-year natural aging at ambient temperatures, and 15-year natural aging followed by accelerative aging at 200°C. The changes in mechanical property during and after the aging processes were examined using microhardness and tensile-testing methods. During the early stages of artificial aging at 200°C, the microhardness of WQ-U6Nb alloy increased, i.e., age hardening, as a result of the development of nanoscale modulation caused by spinodal decomposition. Coarsening of the modulated structure occurred after a prolonged aging at 200°C for 16 hours, and it led to a decrease of microhardness, i.e., age softening. Phase instability was also found to occur in WQ-U6Nb alloy that was subjected to a 15-year natural aging at ambient temperatures. The formation of partially ordered domains resulting from a spinodal modulation with an atomic-scale wavelength rendered the appearance of swirl-shape antiphase domain boundaries (APBs) observed in TEM images. Although it did not cause a significant change in microhardness, 15-year natural aging has dramatically affected the aging mechanisms of the alloy isothermally aged at 200°C. Microhardness values of the NA alloy continuously increased after isothermal aging at 200°C for 96 hours as a result of the phase decomposition of partially ordered domains into Nb-depleted α phase and Nb-enriched U3Nb ordered phase in the alloy. It is concluded that the long-term natural aging changes the transformation pathway of WQ-U6Nb, and it leads to order-disorder transformation and precipitation hardening of WQ-U6Nb alloy.
Thorium-Based Thin Films as Highly Reflective Mirrors in the EUV
Authors: Johnson Jed E. , Allred David D. , Turley R. Steven , Evans William R. , Sandberg Richard L.
Published: April 2011

As applications for extreme ultraviolet (EUV) radiation have been identified, the demand for better optics has also increased. Thorium and thorium oxide thin films (19 to 61 nm thick) were RF-sputtered and characterized using atomic force microscopy (AFM), spectroscopic ellipsometry, low-angle x-ray diffraction (LAXRD), x-ray photoelectron spectroscopy (XPS), and x-ray absorption near edge structure (XANES) in order to assess their capability as EUV reflectors. Their reflectance and absorption at different energies were also measured and analyzed at the Advanced Light Source in Berkeley. The reflectance of oxidized thorium is reported between 2 and 32 nm at 5, 10, and 15 degrees from grazing. The imaginary component of the complex index of refraction, β, is also reported between 12.5 and 18 nm. Thin films of thorium were found to reflect better between 6.5 and 9.4 nm at 5 degrees from grazing than all other known materials, including iridium, gold, nickel, uranium dioxide, and uranium nitride. The measured reflectance does not coincide with reflectance curves calculated from the Center for X-Ray Optics (CXRO) atomic scattering factor data. We observe large energy shifts of up to 20 eV, suggesting the need for better film characterization and possibly an update of the tabulated optical constants.
Phase Composition and Leach Resistance of Actinide-Bearing Murataite Ceramics
Authors: Stefanovsky Sergey , Yudintsev S.V. , Nikonov B.S. , Mokhov A.V. , Perevalov S.A. , Stefanovsky O.I. , Ptashkin A.G.
Published: April 2011

Phase composition of the murataite-based ceramics containing 10 wt.% ThO2, UO2, NpO2 or PuO2 and leaching of actinides using a MCC-1 procedure were studied. The ceramics were prepared by melting of oxide mixtures in Pt ampoules in air at ∼1500 °C. They are composed of predominant murataite-type phases and contain traces of extra phases (rutile, crichtonite, perovskite). At least two murataite-related phases with five- and eight-fold elementary fluorite unit cell (5C and 8C) were simultaneously observed. Minor phase 3C (murataite) in the ceramics doped with ThO2 and UO2 was also found. In the Th-bearing sample the 5C phase prevails over the 8C phase. In the U-bearing ceramic they co-exist in comparable amounts. The sample produced at 1500 °C contains crichtonite whereas the ceramic produced at lower temperature (1400 °C) contained rutile. Higher temperature favors further rutile reactions with formation of crichtonite. The Np- and Pu-doped ceramics are also composed of major the 5C and the 8C phases and minor rutile and crichtonite (in Pu-loaded sample only). Unlike the sample prepared under slightly re-ducing conditions (in glassy carbon crucible) the Pu-doped ceramic produced under neutral conditions (in Pt ampoule) doesn’t contain perovskite-type phase. Occurrence of perovskite in the first sample was sup-posed to be due to reduction of some Pu(IV) to Pu(III) during experiment. Leach rates (7-day MCC-1 test, 90 °C) of the actinide elements from all the ceramics studied are at the level of 10-6-10-7 g/(m2·day).
Pressure induced phase transitions in AmCm alloy
Authors: Li Sa , Ahuja Rajeev , Johansson Borje
Published: April 2011

We have studied the crystal structure of the AmCm binary alloy under high pressure by means of first-principles self-consistent total-energy calculations using the generalized gradient approximation (GGA) for the density functional theory (DFT). The virtual crystal approximation (VCA) is used for the description of the alloy system. In the present study, we investigated the double hexagonal (P63/mmc) structure, the face centered cubic (Fm3m) structure, the face-centered orthorhombic (Fddd) structure and the primitive orthorhombic (Pnma) structure for the AmCm alloy. Antiferromagnetic calculations have been compared with ferromagnetic calculations for all these phases. Our results are in general good agreement with recent experiment performed by Lindbaum et al. [J. Phys.: Condens. Matter. 15, S2297 (2003)].
High Pressure Structural transitions in Cm metal
Authors: Ahuja Rajeev , Li Sa , Johansson Börje
Published: April 2011

The high pressure behaviour of Cm metal is investigated theoretically using ab initio electronic structure methods. Our calculations reproduce the structural phase transitions which are obsereved in recent experiment performed by Heatman et al. [Science 309, 110 (2005)]. Calculated transition pressures are in reasonable agreement with the experiment. Calculations performed in antiferromagnetic state is essential to reproduce the stability of Cm-III phase. Thus stability of Cm-III phase is related to the spin polarization of 5f electrons.
Theoretical study of protactinium at high pressure
Authors: Johansson Börje , Li Sa , Eyvaz Eyvaz , Ahuja Rajeev
Published: April 2011

We have studied the crystal structure of Pa metal under high pressure by means of first-principles calculations based on the density functional theory (DFT) using the generalized gradient approximation (GGA). The body centered tetragonal (bct) to orthorhombic (α-U) phase transition was calculated to take place at 29 GPa and with a volume change of 1.3%. The calculated c/a for the bct phase reaches the ideal c/a value (0.816) at around 50 GPa. A bulk modulus of 113 GPa was derived from a Murnaghan equation of state (EOS) fitting procedure. Our results are in general good agreement with recent experiment performed by Haire et al. [Phys. Rev. B 67, 134101 (2003)]. We have also calculated the phonon spectrum for fcc, bct and bcc Pa. The latter gives imaginary frequencies showing the low temperature instability of this crystallographic phase for Pa.
Behavior of Uranium(VI) during HEDPA Leaching for Aluminum Dissolution in Tank Waste Sludges
Authors: Powell Brian Anthony , Rao Linfeng , Nash Kenneth L. , Martin Leigh
Published: April 2011

Batch adsorption/dissolution experiments were conducted to examine the interactions between 233U(VI) and a synthetic aluminum oxyhydroxide (boehmite, γ-AlOOH) in 1.0M NaCl suspensions containing 1-hydroxyethane-1,1-diphosphonic acid (HEDPA). In the pH range 4 to 9, complexation of Al(III) by HEDPA significantly enhanced dissolution of boehmite. This phenomenon was especially pronounced in the neutral pH region where the solubility of aluminum, in the absence of complexants, is limited by the formation of sparsely soluble aluminum hydroxides. At high pH levels, dissolution of synthetic boehmite was inhibited by HEDPA, likely due to sorption of Al(III)/HEDPA complexes. Addition of HEDPA to equilibrated U(VI)-synthetic boehmite suspensions yielded an increase in the aqueous phase uranium concentration. The concentration of uranium continually increased over 59 days. Partitioning of uranium between the solid and aqueous phase was found to correlate well with HEDPA partitioning.
On-line Data Management for High-throughput Experimentation
Authors: Lippmaa Mikk , Meguro Shinya , Ohnishi Tsuyoshi , Koinuma Hideomi , Takeuchi Ichiro
Published: April 2011

We discuss visualization and data dependency issues related to managing sample characterization data from high-throughput experiments. We are developing software for on-line storage, sharing, and visualization of data from combinatorial or high-throughput experiments. The system is based on a centralized database and a Web interface that can be accessed from any networked computer. The greatest challenge facing us is the variety of data types and formats that such a system has to support so that data from many different sources, i.e. from synthesis and characterization instruments, could be combined. In order to minimize the software development effort, we have developed generalized extensible markup language (XML) schema for storing and processing experimental data. The use of a standard data format like XML, together with the relevant schema definitions can be used to implement storage, processing, visualization and other tools that are generic and thus greatly simplify the task of managing high-throughput experiments.
An SEM Study Of The Effect of Altering the Reaction pH on Fluoride Catalysed Silica Sol-Gel Templating Of Self-Assembling Peptide Fibrils
Authors: Meegan Jonathan , Aggeli Amalia , Ansell Richard J , Brown Andy P , Brydson Rik
Published: April 2011

The templating of hydrolysed silane species by self-assembling peptide fibrils has been extensively studied at the Centre for Self Organising Molecular Systems based in the University of Leeds . In this paper we present an SEM based study of the pH effects on the peptide fibril templates and the fluoride catalysed templating chemistry and the resulting silica nanotubes.
Adhesion Properties between Swollen Hydrogels in Air
Authors: Sakasegawa Daisuke , Sato Takaya , Goto Motoaki , Suzuki Atsushi
Published: April 2011

Adhesion between swollen hydrogels was studied using a simple tack-evaluation technique by a point contact in air at room temperature. The hydrogel used here was poly(sodium acrylate) (PSA) gel physically cross-linked by aluminum ions. The adhesion force and the separation energy showed a power-law increase with separation velocity, normal force, and waiting period　prior to separate. Effects of the degrees of protonation in PSA as well as of dehydration on the adhesive properties are also presented. The results are discussed in terms of the surface molecular interaction and the bulk elastic and viscous properties.
Nano-Thermometry: Transmission Electron Microscopy of Femtosecond Laser Irradiated Co/Si Multilayer Thin Foils
Authors: Picard Yoosuf , Yalisove Steven M.
Published: April 2011

Pre-thinned foils composed of amorphous silicon and polycrystalline cobalt were irradiated using femtosecond pulse-length lasers at fluences sufficient for ablation (material removal). The resultant ablated hole and surrounding vicinity was studied using transmission electron microscopy to determine modifications to the structure. Evidence of cobalt silicide formation was observed within a 3 micron radius of the laser hole edge by use of selected area electron diffraction (SAED). In addition, elongated grains of crystalline silicon was observed within 500 nm of the laser hole edge, indicating melting of the amorphous silicon and heat dissipation slow enough to allow recyrstallization. This initial work demonstrates the use of pre-designed nanostructured multilayer systems as a method for nanoscale profiling of heat dissipation following pulsed laser irradiation.
Poly(methyl phenyl siloxane) in Random Nanoporous Glasses: Comparison of coated and uncoated confining surfaces
Authors: Schöenhals Andreas , Goering Harald , Schick Christoph
Published: April 2011

The effect of a nanometer confinement on the molecular dynamics of poly(methyl phenyl siloxane) (PMPS) was studied by dielectric spectroscopy (DS) and temperature modulated DSC (TMDSC). As confining hosts random nanoporous glasses with nominal pore sizes of 2.5 nm – 20 nm have been used. Epically it is focused on the influence of a surface treatment on the dynamical behavior. DS and TMDSC experiments show that for PMPS in 7.5 nm pores the molecular dynamics is faster than in the bulk which originates from an inherent length scale of the underlying molecular motions. There is no influence of the surface treatment on the glassy dynamics for this pore size.

At a pore size of 5 nm the temperature dependence of the relaxation times changes from a Vogel / Fulcher / Tammann like behavior to an Arrhenius one where the apparent activation energy depends on pore size. For silanized pores a higher value (102 kJ / mol) is found than for natives pores (73 kJ / mol). For a pore size of 2.5 nm the activation energy is independent of the surface treatment. The value of ca. 40 kJ / mol points to a real localized process.

The increment of the specific heat capacity at the glass transition depends strongly on pore size and vanishes at a finite length scale which can be regarded as minimal length scale for glass transition to appear. The actual value depends on surface treatment. From this difference the thickness of an immobilized boundary layer of about 1 nm is estimated for uncoated pores.