bluuebunny/crossref_metadata_2025 huggingface dataset:
Controllable Multicolor Upconversion Luminescence by Tuning the NaF Dosage
Authors: Li Hao , Wang Leyu
Published: October 2013

Multicolor upconversion (UC) luminescence of NaYF4:Yb3+/Er3+ nanoparticles (NPs) was successfully tuned by simply controlling the NaF dosage. Unlike UC nanocrystals previously reported in the literature with multicolor emission obtained by varying the rare‐earth dopants, the current work developed a new approach to tune the UC emission color by controlling the NaF concentration without changing the ratio and dosage of rare‐earth ions. TEM and powder XRD were used to characterize the shape, size, and composition of the UC luminescent nanocrystals. The luminescence images, emission spectra, and multicolor emission mechanism of the NPs have also been demonstrated. As a result of the excellent ability of this new method to manipulate color emission, this will open up new avenues in the areas of bioprobes, light‐emitting devices, color displays, lasers, and so forth. To demonstrate their biological applications, the water‐stable, biocompatible, and bioconjugatable NaYF4:Yb3+/Er3+@poly(acrylic acid) NPs were synthesized by this developed strategy and applied in targeted‐cell UC luminescence imaging.
Quantified pathologic response assessed as residual tumor burden is a predictor of recurrence‐free survival in patients with rectal cancer who undergo resection after neoadjuvant chemoradiotherapy
Authors: Agarwal Atin , Chang George J. , Hu Chung‐Yuan , Taggart Melissa , Rashid Asif , Park In J. , You Y. Nancy , Das Prajnan , Krishnan Sunil , Crane Christopher H. , Rodriguez‐Bigas Miguel , Skibber John , Ellis Lee , Eng Cathy , Kopetz Scott , Maru Dipen M.
Published: October 2013

BACKGROUND

The current study was conducted to determine whether quantified pathologic response assessed as a percentage of residual tumor cells is predictive of recurrence‐free survival (RFS) in patients with rectal cancer.

METHODS

The authors studied 251 patients with rectal adenocarcinoma who were treated with neoadjuvant chemoradiation and radical resection. Quantified pathologic response was defined as an estimated percentage of residual cancer cells in relation to the tumor bed: complete, no residual cancer cells; near‐complete, ≤ 5% residual cancer cells; major, > 5%, and < 50% residual cancer cells; and minor, ≥ 50% residual cancer cells. The reproducibility of quantified pathologic response between 2 pathologists was assessed using tumors from 55 randomly selected patients who did not demonstrate a complete response.

RESULTS

Pathologic response was complete in 21% of patients, near‐complete in 20% of patients, major in 37% of patients, and minor in 22% of patients. Nineteen percent of patients had ypT0N0 disease, 27% had ypT1‐2N0 disease, 21% had ypT3‐4N0 disease, and 33% had N+ disease. The 5‐year RFS rates by category of quantified pathologic response were as follows: complete, 95%; near‐complete, 88%; major, 69%; and minor, 61% (P < .001). Major and minor response, high histologic grade, and perineural invasion were found to be significant predictors of decreased RFS on multivariate analysis. The 5‐year RFS rates for patients with ypT3‐4 or N+ disease were better for those with a near‐complete response (94%) compared with those with a major (64%) or minor (61%) response (P < .02). Moderate to substantial agreement was observed between the 2 pathologists (κ = 0.72).

CONCLUSIONS

Quantified pathologic response is a predictor of RFS in patients with rectal adenocarcinoma and stratifies patients with high pathologic stage disease. Cancer 2013;119:4231–4241. © 2013 American Cancer Society.
Hot corrosion behavior of slip‐cast alumina‐chrome refractory crucible against molten glass
Authors: Nath M. , Dana K. , Gupta S. , Tripathi H. S.
Published: October 2013

Alumina‐chrome bodies were prepared by slip casting route. Slip casted bodies were sintered in the temperature range of 1550–1650 °C in reducing atmosphere with 2 h soaking time at peak temperature. Highly dense alumina‐chrome body with bulk density 4.24 g/cc and almost zero apparent porosity were obtained at 1650 °C. The hot corrosion test of alumina‐chrome crucible against borosilicate glass was carried out in static condition at 1200 °C for 4 h. The study of the glass–refractory interface after static corrosion test was done by scanning electron microscopy, energy dispersive X‐ray spectroscopy analysis and X‐ray diffraction (XRD) analysis. The XRD pattern of glass–refractory interface does not show formation of any new phases. Elemental mapping of glass–refractory interface indicates corrosion up to a depth of 70 µm has taken place in the form of ion migration.
Retarding the corrosion of iron by inhomogeneous magnetic fields
Authors: Sueptitz R. , Tschulik K. , Uhlemann M. , Eckert J. , Gebert A.
Published: October 2013

The influence of a magnetic field yielding high magnetic flux densities and high flux density gradients on the free corrosion behavior of iron in a low concentrated acidic solution with and without chloride ions is studied by long time exposure experiments and electrochemical impedance spectroscopy (EIS). A decrease of the corrosion rate in electrode surface regions of high magnetic flux density is detected. This decrease of the dissolution rate is significantly stronger in the presence of chloride ions. The observed effects are discussed on the basis of the magnetically induced forces acting on the ions present in the solution, the surface coverage fraction of adsorbed species, and the stability of these adsorbed species.
D‐Methionine as a biofilm dispersal signaling molecule enhanced tetrakis hydroxymethyl phosphonium sulfate mitigation of Desulfovibrio vulgaris biofilm and biocorrosion pitting
Authors: Xu D. , Li Y. , Gu T.
Published: October 2013

Biocorrosion is also known as microbiologically influenced corrosion (MIC). It is often caused by sulfate reducing bacteria (SRB) biofilms. More effective biocide treatment methods are desired due to environmental regulations and increasing costs. Recently, several publications revealed that some D‐amino acids are signaling molecules for bacterial biofilm dispersal. In this work, tetrakis hydroxymethyl phosphonium sulfate (THPS) was combined with D‐methionine for the mitigation of Desulfovibrio vulgaris (ATCC 7757) biofilm in the full ATCC 1249 medium and a modified medium with only four ingredients, i.e., magnesium sulfate, sodium lactate, ferrous ammonium sulfate hexahydrate, and yeast extract at concentrations 1/4 of those in the full medium, as well as MIC pitting of C1018 carbon steel. D‐Methionine alone even at a concentration of 1000 ppm w/w and 50 ppm (active concentration) THPS alone were both found ineffective. However, a synergistic biocide combination consisting of 50 ppm THPS and 100 ppm D‐methionine was highly effective and even better than 500 ppm THPS used alone. Although D‐methionine alone has no biocidal effects, its biofilm dispersal effect can convert sessile cells to planktonic cells under a biocide stress. This is very useful in biofilm treatment because planktonic cells are much easier to treat than sessile cells using biocides.
Critical characteristics of corrosion product film obtained by fluid structure interaction
Authors: Zhu X. L. , Lu X. F. , Ling X.
Published: October 2013

The critical characteristics of corrosion product film (CPF) were investigated, and the mechanism of flow‐accelerated corrosion (FAC) was discussed by improving the multiple reference frame method (MRF) using the space temporary coordinate system. The improved MRF was used to accomplish fluid structure interaction (FSI) numerical simulation for FAC testing machine with a pre‐filming specimen. The new numerical method for the simulation of the critical characteristics of the CPF was proposed by coupling FSI and contact analysis in COMSOL Multiphysics software based on Hertz theory, which was used to calculate the critical characteristics of the specimen. The results reveal that the deformation and stress of the CPF increased with increasing temperature and flow velocity. The critical flow velocity was higher than the pre‐filming flow velocity and increased with increasing temperature. The calculation results are consistent with those of the linear polarization experiment.
Microstructural evolution and corrosion behavior of Al25Ti25Ga25Be25 equi‐molar composition alloy
Authors: Fazakas É. , Wang J. Q. , Zadorozhnyy V. , Louzguine‐Luzgin D. V. , Varga L. K.
Published: October 2013

The microstructure of light element containing Al25Ti25Ga25Be25 equi‐molar composition alloy was investigated by X‐ray diffractometry and scanning electron microscopy, while the corrosion behavior was tested in 1 M sulfuric acid solution (H2SO4) at ambient temperature (298 K). The results show that the alloy displays good general corrosion resistance. The influence of the microstructure and morphology of the constituent phases is also evaluated.
Corrosion performance of Zn–Mg–Al coated steel in accelerated corrosion tests used in the automotive industry and field exposures
Authors: LeBozec N. , Thierry D. , Peltola A. , Luxem L. , Luckeneder G. , Marchiaro G. , Rohwerder M.
Published: October 2013

The corrosion performance of Zn–Mg(1–2%)–Al(1–2%) (ZMA) coatings has been compared to zinc–iron alloy (galvannealed, GA) and zinc–aluminum coating (Zn–5Al, Galfan) as well as to conventional zinc coatings produced by hot‐dip galvanization (HDG) and electrogalvanization (EG). For this purpose, cosmetic samples (painted and uncoated) and hem‐flange panels were produced. Their corrosion performance was compared in three different accelerated corrosion tests, as regularly used by the automotive industry, e.g., VDA621‐415, N‐VDA (VDA233‐102), and Volvo STD 423‐0014. As can be concluded from our results, the behavior of ZMA coatings was strongly dependent on the testing conditions as well as on the configuration of the samples. The advantageous effect of ZMA coating was more pronounced in open situations than in confined ones, irrespective of the testing conditions. ZMA coatings provided a significant improvement in comparison to conventional coatings in tests involving a significant salt load such as VDA621‐415 or neutral salt spray especially on cosmetic configurations. By contrast, the beneficial effect of ZMA coatings was less obvious in tests with lower salt load (VDA233‐102, Volvo STD423‐0014), particularly when considering cosmetic corrosion on painted samples and corrosion in confinement. Interestingly, no significant differences were observed between samples with varying Al and Mg content in the metallic coating (1–2% each). The results were compared to data from field exposure at stationary sites.
Galvanic corrosion behavior of NiC filled conductive silicone rubber coupled to AZ31 magnesium alloys
Authors: Zhou H. , Xia Z. D. , Li Z. , Guo F.
Published: October 2013

The galvanic corrosion behaviors of NiC filled conductive silicon rubber (CSR) with different resistivity coupled to magnesium alloys were investigated in 3.5% sodium chloride solution at different temperatures. Such investigations were carried out by means of electrochemical measurement, weight‐loss determination, and surface characterization. The results indicated that the changes of CSRs' resistivity and the temperature of the electrolyte would affect the Tafel slope, cathodic corrosion current, and linear polarization resistance of the cathodic branch of the polarization curve. The lower the resistivity, the larger the average galvanic corrosion current density and the average galvanic corrosion rate of Mg alloys at the same temperature. The corrosion morphology revealed that the greater the corrosion current density, the more serious the corrosion on the surface of Mg alloys.
Influence of irregularities in the electrolyte on the cathodic protection of steel: A numerical and experimental study
Authors: Montoya R. , Nagel V. , Galván J. C. , Bastidas J. M.
Published: October 2013

This paper shows how the last algebraic matricial form can be obtained when the finite element method is used to approximate the potential distribution of a cathodic protection system that includes low conductivity irregularities in the electrolyte away from, close to and directly on the cathode. In order to study the influence of the resistivity of these irregularities on the possibilities of steel protection, five conductivities were analysed. The numerical results, validated with COMSOL® Multiphysics, show the importance of considering irregularities in the domain in order to prevent systems from becoming unprotected. The experimental data agrees with the theoretical data.
The effect of a nickel alloy coating on the corrosion of furnace wall tubes in a waste wood fired power plant
Authors: Alipour Y. , Henderson P. , Szakálos P.
Published: October 2013

The use of waste wood as a fuel in power plants is becoming more widespread in Europe, because it is a renewable energy source with a lower cost than forest fuel. However it is more corrosive than coal and corrosion problems have arisen in the furnace wall area of a low NOx heat and power boiler. The furnace walls are made of a low alloy steel which has been coated in some parts with a nickel alloy to reduce corrosion. In this work, furnace tubes coated with a nickel alloy were compared to the uncoated tubes of the low alloy steel 16Mo3 after 3 years of exposure in the boiler. The nickel alloy coating and uncoated material were also compared with more controlled testing on a corrosion probe lasting for about 6 weeks. The corrosion rates were measured and the samples were chemically analysed by SEM/EDS/WDS and XRD methods. The corrosive environment was also modelled with Thermo‐Calc software. The corrosion rates measured from the probe and tube samples of 16Mo3 agreed well with each other, implying linear corrosion rates. The results also showed that the use of nickel alloy coatings changes the corrosion mechanism, which leads to a dramatic reduction in the corrosion rate. The results are discussed in terms of the corrosion mechanisms and thermodynamic stability of the corrosion products.
Air‐Spun PLA Nanofibers Modified with Reductively Sheddable Hydrophilic Surfaces for Vascular Tissue Engineering: Synthesis and Surface Modification
Authors: Ko Na Re , Sabbatier Gad , Cunningham Alexander , Laroche Gaétan , Oh Jung Kwon
Published: October 2013

Polylactide (PLA) is a class of promising biomaterials that hold great promise for various biological and biomedical applications, particularly in the field of vascular tissue engineering where it can be used as a fibrous mesh to coat the inside of vascular prostheses. However, its hydrophobic surface providing nonspecific interactions and its limited ability to further modifications are challenges that need to be overcome. Here, the development of new air‐spun PLA nanofibers modified with hydrophilic surfaces exhibiting reduction response is reported. Surface‐initiated atom transfer radical polymerization allows for grafting pendant oligo(ethylene oxide)‐containing polymethacrylate (POEOMA) from PLA air‐spun fibers labeled with disulfide linkages. The resulting PLA‐ss‐POEOMA fibers exhibit enhanced thermal stability and improved surface properties, as well as thiol‐responsive shedding of hydrophilic POEOMA by the cleavage of its disulfide linkages in response to reductive reactions, thus tuning the surface properties.

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New $ \mathcal{N} $ = 1 dualities from orientifold transitions Part I: field theory
Authors: García-Etxebarria Iñaki , Heidenreich Ben , Wrase Timm
Published: October 2013

Abstract

We report on a broad new class of$ \mathcal{N} $= 1 gauge theory dualities which relatethe worldvolume gauge theories of D3 branes probing different orientifolds of the sameCalabi-Yau singularity. In this paper, we focus on the simplest example of these newdualities, arising from the orbifold singularity$ {{\mathbb{C}}^3}/{{\mathbb{Z}}_3} $. We present extensive checks of theduality, including anomaly matching, partial moduli space matching, matching of discretesymmetries, and matching of the superconformal indices between the proposed duals. Wethen present a related duality for thedP1singularity, as well as dualities for the$ {{\mathbb{F}}_0} $andY4,0singularities, illustrating the breadth of this new class of dualities. In a companion paper, we show that certain infinite classes of geometries which include$ {{\mathbb{C}}^3}/{{\mathbb{Z}}_3} $anddP1all exhibit such dualities, and argue that their ten-dimensional origin is the SL(2,$ \mathbb{Z} $) self-duality oftype IIB string theory.
Que veut dire Bachelard par « rationalisme appliqué » ?
Authors: Tiles Mary
Published: October 2013

Bachelard s’intéresse au processus d’acquisition de la connaissance, qui comprend l’activité des sujets connaissant. Il ne conçoit pas le raisonnement comme identique à la logique mais comme résultant du déploiement des mathématiques dans l’organisation à la fois théorique et expérimentale, et c’est pourquoi il traite de la science comme des mathématiques appliquées. L’application en question est matérielle et technique; il s’intéresse à la rationalité inhérente au matérialisme technique et à la concrétude inhérente au rationalisme appliqué.
Förderung der Lebenskompetenz und Resilienz in Kindertageseinrichtung und Grundschule
Authors: Fröhlich-Gildhoff Klaus , Rönnau-Böse Maike
Published: October 2013

In diesem Beitrag wird ein Überblick über die Projekte der Förderung der seelischen Gesundheit – operationalisiert durch das Resilienz- und Lebenskompetenzkonzept – in Kindertageseinrichtungen am Freiburger Zentrum für Kinder- und Jugendforschung und die zugrundelegenden theoretischen Konstrukte gegeben. Anschließend werden Forschungsdesign und Ergebnisse der Studie „Prävention zur Verhinderung von Exklusion – Förderung der seelischen Gesundheit in Einrichtungen der Kindertagesbetreuung in Quartieren mit besonderen Problemlagen“ referiert. Es konnte gezeigt werden, dass mittels eines Mehrebenen-Ansatzes im Setting Kita der Selbstwert der Kinder gesteigert und z. T. kognitive Entwicklungsparameter positiv verändert werden konnten. Die Eltern berichteten über steigende Erziehungssicherheit und die pädagogischen Fachkräfte über eine erhöhte Arbeitszufriedenheit.
Zusammenhang von motorischen Fähigkeiten, Intelligenz und sozial-emotionalem Verhalten bei 3 – 6jährigen – eine Pilotstudie
Authors: Schwarz Rolf
Published: October 2013

Die Entwicklung sozial-emotionaler Kompetenz hängt eng mit Delinquenz, Schulreife/-erfolg sowie psychischer und physischer Gesundheit zusammen. Diese fundamentale Bedeutung wird gleichzeitig von einer hohen Zahl auffälliger Kinder in der BRD konterkariert. Da Bewegungsumfang und -intensität in ausreichender Quantität und Qualität die notwendige Grundlage für eine allgemein positive Entwicklung für Kinder darstellen, erhalten bewegungspädagogische Anteile innerhalb präventiver Programme zu sozial-emotionalem Verhalten einen möglicher Weise hohen Stellenwert. Gleichwohl stellt der empirisch geprüfte Zusammenhang zwischen motorischen Fähigkeiten und sozial-emotionalem Verhalten im Kindergartenalter ein erhebliches Forschungsdesiderat dar. Im Beitrag werden erste querschnittliche Zusammenhänge sowie Varianzen auf Grundlage der BeBi-Studie 3 – 6 („Bewegung und Bildung bei 3 – 6jährigen“) vorgestellt. Die Ergebnisse zeigen geschlechterspezifische Unterschiede bei sozial-emotionalen Auffälligkeiten zu Lasten der Jungen. Betroffen sind vor allem motorisch schwache Kinder. Die Motorik allgemein steht nur in geringem Zusammenhang mit Verhaltensauffälligkeiten und korreliert stärker mit dem IQ. Insbesondere der SED-Anteil der Intelligenz (Arbeitsgedächtnis) zeigt sich als möglicher Prädiktor für das Auftauchen von sozial-emotionalen Abweichungen.
[11C]5-HTP and microPET are Not Suitable for Pharmacodynamic Studies in the Rodent Brain
Authors: Visser Anniek KD , Ramakrishnan Nisha K , Willemsen Antoon TM , Di Gialleonardo Valentina , de Vries Erik FJ , Kema Ido P , Dierckx Rudi AJO , van Waarde Aren
Published: October 2013

The PET tracer [11C]5-hydroxytryptophan ([11C]5-HTP), which is converted to [11C]5-hydroxytryptamine ([11C]5-HT) by aromatic amino acid decarboxylase (AADC), is thought to measure 5-HT synthesis rates. But can we measure these synthesis rates by kinetic modeling of [11C]5-HTP in rat? Male rats were scanned with [11C]5-HTP (60 minutes) after different treatments. Scans included arterial blood sampling and metabolite analysis. 5-HT synthesis rates were calculated by a two-tissue compartment model (2TCM) with irreversible tracer trapping or Patlak analysis. Carbidopa (inhibitor peripheral AADC) dose-dependently increased [11C]5-HTP brain uptake, but did not influence 2TCM parameters. Therefore, 10 mg/kg carbidopa was applied in all subsequent study groups. These groups included treatment with NSD 1015 (general AADC inhibitor) or p-chlorophenylalanine (PCPA, inhibitor of tryptophan hydroxylase, TPH). In addition, the effect of a low-tryptophan (Trp) diet was investigated. NSD 1015 or Trp depletion did not affect any model parameters, but PCPA reduced [11C]5-HTP uptake, and the k3. This was unexpected as NSD 1015 directly inhibits the enzyme converting [11C]5-HTP to [11C]5-HT, suggesting that trapping of radioactivity does not distinguish between parent tracer and its metabolites. As different results have been acquired in monkeys and humans, [11C]5-HTP-PET may be suitable for measuring 5-HT synthesis in primates, but not in rodents.
Hypothesis of Lipid-Phase-Continuity Proton Transfer for Aerobic ATP Synthesis
Authors: Morelli Alessandro M , Ravera Silvia , Calzia Daniela , Panfoli Isabella
Published: October 2013

The basic processes harvesting chemical energy for life are driven by proton (H+) movements. These are accomplished by the mitochondrial redox complex V, integral membrane supramolecular aggregates, whose structure has recently been described by advanced studies. These did not identify classical aqueous pores. It was proposed that H+ transfer for oxidative phosphorylation (OXPHOS) does not occur between aqueous sources and sinks, where an energy barrier would be insurmountable. This suggests a novel hypothesis for the proton transfer. A lipid-phase-continuity H+ transfer is proposed in which H+ are always bound to phospholipid heads and cardiolipin, according to Mitchell's hypothesis of asymmetric vectorial H+ diffusion. A phase separation is proposed among the proton flow, following an intramembrane pathway, and the ATP synthesis, occurring in the aqueous phase. This view reminiscent of Grotthus mechanism would better account for the distance among the Fo and F1 moieties of FoF1–ATP synthase, for its mechanical coupling, as well as the necessity of a lipid membrane. A unique active role for lipids in the evolution of life can be envisaged. Interestingly, this view would also be consistent with the evidence of an OXPHOS outside mitochondria also found in non-vesicular membranes, housing the redox complexes.
The mutational landscape of phosphorylation signaling in cancer
Authors: Reimand Jüri , Wagih Omar , Bader Gary D.
Published: October 2013

Somatic mutations in cancer genomes include drivers that provide selective advantages to tumor cells and passengers present due to genome instability. Discovery of pan-cancer drivers will help characterize biological systems important in multiple cancers and lead to development of better therapies. Driver genes are most often identified by their recurrent mutations across tumor samples. However, some mutations are more important for protein function than others. Thus considering the location of mutations with respect to functional protein sites can predict their mechanisms of action and improve the sensitivity of driver gene detection. Protein phosphorylation is a post-translational modification central to cancer biology and treatment and frequently altered by driver mutations. Here we used our ActiveDriver method to analyze known phosphorylation sites mutated by single nucleotide variants (SNVs) in The Cancer Genome Atlas Research Network (TCGA) pan-cancer dataset of 3,185 genomes and 12 cancer types. Phosphorylation-related SNVs (pSNVs) occur in ~90% of tumors, show increased conservation and functional mutation impact compared to other protein-coding mutations and are enriched in cancer genes and pathways. Gene-centric analysis found 150 known and candidate cancer genes with significant pSNV recurrence. Using a novel computational method, we predict that 29% of these mutations directly abolish phosphorylation or modify kinase target sites to rewire signaling pathways. This analysis shows that incorporation of information about protein signaling sites will improve computational pipelines for variant function prediction.
How does the metabolism of tumour cells differ from that of normal cells
Authors: Amoêdo Nívea Dias , Valencia Juan Perez , Rodrigues Mariana Figueiredo , Galina Antonio , Rumjanek Franklin David
Published: October 2013

Tumour cells thrive in environments that would be hostile to their normal cell counterparts. Survival depends on the selection of cell lines that harbour modifications of both, gene regulation that shifts the balance between the cell cycle and apoptosis and those that involve the plasticity of the metabolic machinery. With regards to metabolism, the selected phenotypes usually display enhanced anaerobic glycolysis even in the presence of oxygen, the so-called Warburg effect, and anabolic pathways that provide precursors for the synthesis of lipids, proteins and DNA. The review will discuss the original ideas of Otto Warburg and how they initially led to the notion that mitochondria of tumour cells were dysfunctional. Data will be presented to show that not only the organelles are viable and respiring, but that they are key players in tumorigenesis and metastasis. Likewise, interconnecting pathways that stand out in the tumour phenotype and that require intact mitochondria such as glutaminolysis will be addressed. Furthermore, comments will be made as to how the peculiarities of the biochemistry of tumour cells renders them amenable to new forms of treatment by highlighting possible targets for inhibitors. In this respect, a case study describing the effect of a metabolite analogue, the alkylating agent 3BP (3-bromopyruvate), on glycolytic enzyme targets will be presented.
Band-gap energy of heteropoly compounds containing Keggin polyanion-[PVxMo12-xO40]−(3+x) relates to counter-cations and temperature studied by UV-VIS diffuse reflectance spectroscopy
Authors: Sasca Viorel , Popa Alexandru
Published: October 2013

The band gap energy (absorption edge energies) of the pure H3[PMo12O40]·13H2O and H4[PVMo11O40]·13H2O, respectively, supported on SiO2 and SiC and some of its NH4+ and Cs+ salts were determined by different methods. The influence of the counter-cations and the temperature on band gap energy was studied. In this purpose, the diffuse reflectance spectra of above mentioned compounds were registered at different temperatures, and it were transposed in the curves of the Kubelka-Munk function vs. wavelength. The band gap energies were determined by processing of low field energy of the ligand-metal charge transfer band (O2− → Mo6+ and O2− → V5+) usually observed between 200 and 400 nm on these curves. In this aim, the Tauc's relation was adapted for Kubelka-Munk function use and it was plotted for n = 1/2 (direct transition) and 2 (indirect transition) vs. wave energy (photon energy). The intersection of the curves’ tangent drawn to their point of inflection with horizontal axis gives the band gap energy. The other method for calculation of band gap energy was the differential calculus on the Kubelka-Munk function vs. wave energy curve where the x value corresponding to curves’ maximum is the found value. The comparison between experimental band gap values and literature data showed their partial fit. The higher temperature produces the band gap energy diminution as a result of a stronger interaction between Keggin Units, which occurs especially by the crystallization water loss. The Keggin Units isolation one from another by voluminous counter-ion or their spreading on a support leads to a weaker interaction between them and as a consequence, the increasing of absorption edge energy. A linear correlation of the crystallites size with band gap energy was observed.
Natural triple excitations in local coupled cluster calculations with pair natural orbitals
Authors: Riplinger Christoph , Sandhoefer Barbara , Hansen Andreas , Neese Frank
Published: October 2013

In this work, the extension of the previously developed domain based local pair-natural orbital (DLPNO) based singles- and doubles coupled cluster (DLPNO-CCSD) method to perturbatively include connected triple excitations is reported. The development is based on the concept of triples-natural orbitals that span the joint space of the three pair natural orbital (PNO) spaces of the three electron pairs that are involved in the calculation of a given triple-excitation contribution. The truncation error is very smooth and can be significantly reduced through extrapolation to the zero threshold. However, the extrapolation procedure does not improve relative energies. The overall computational effort of the method is asymptotically linear with the system size O(N). Actual linear scaling has been confirmed in test calculations on alkane chains. The accuracy of the DLPNO-CCSD(T) approximation relative to semicanonical CCSD(T0) is comparable to the previously developed DLPNO-CCSD method relative to canonical CCSD. Relative energies are predicted with an average error of approximately 0.5 kcal/mol for a challenging test set of medium sized organic molecules. The triples correction typically adds 30%–50% to the overall computation time. Thus, very large systems can be treated on the basis of the current implementation. In addition to the linear C150H302 (452 atoms, >8800 basis functions) we demonstrate the first CCSD(T) level calculation on an entire protein, Crambin with 644 atoms, and more than 6400 basis functions.
Properties of axisymmetric Bernstein modes in an infinite-length non-neutral plasma
Authors: Hart Grant W. , Spencer Ross L.
Published: October 2013

We have observed axisymmetric Bernstein modes in an infinite-length particle-in-cell code simulation of a non-neutral plasma. The plasmas considered were in global thermal equilibrium and there were at least 50 Larmor radii within the plasma radius. The density of the plasma in the simulation is parameterized by β, the ratio of the central density to the density at the Brillouin limit. These modes have m = 0 and kz=0, where the eigenfunctions vary as ei(mθ+kzz). The modes exist both near the Coriolis-shifted (by the plasma rotation) upper-hybrid frequency, ωuh=ωc2−ωp2, and near integer multiples (2, 3, etc.) of the Coriolis-shifted cyclotron frequency (called the vortex frequency, ωv=ωc2−2ωp2). The two modes near ωuh and 2ωv are the main subject of this paper. The modes observed are clustered about these two frequencies and are separated in frequency at low plasma density roughly by δω≈10(rL/rp)2ωp2/ωc. The radial velocity field of the modes has a J1(kr) dependence in the region of the plasma where the density is nearly constant. For any given density, there are three classes of modes that exist: (1) The fundamental mode is slightly above the upper-hybrid frequency, (2) the upper branch is above the higher of ωuh and 2ωv, and (3) the lower branch is below the lower of ωuh and 2ωv, with similar values of k for both the upper and the lower frequency branches. The modes are fully kinetic and the resulting pressure tensor has significant anisotropy, including off-diagonal terms. A Vlasov analysis of these modes considering only particle resonances up to 2ωv produces a radial mode differential equation whose solution agrees well with the simulations, except at high density (β greater than about 0.9) where higher-order resonances become important.
Adsorption-desorption characteristics of water on silico-alumino-phosphate-34 molecular sieve for cooling and air conditioning
Authors: Chen H. J. , Cui Q. , Li Q. G. , Zheng K. , Yao H. Q.
Published: October 2013

SAPO (silico-alumino-phosphate) molecular sieves might be promising for adsorption refrigeration driven by low-grade heat source due to their weak polar frameworks. The SAPO-34 molecular sieve was synthesized using a hydrothermal method. Its crystal phase, morphology, and microstructure were characterized by X-ray diffraction, scanning electron microscopy, and N2 sorption isotherms, respectively. Vacuum gravimetric method and thermo-balance were applied to analyze the water adsorption and desorption performance, respectively. Results show that the synthesized molecular sieve has characteristic diffraction peaks of SAPO-34, regular crystal grains, a microporous structure with size of 0.4–0.6 nm, and a specific surface area of 545.8 m2/g. Water adsorption strength on SAPO-34 is between that on 13X molecular sieve and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake reaches 0.35 kg/kg, 25% higher than that on 13X. Dubinin-Astakhov equation is able to well fit SAPO-34 water uptake isotherm to some extent, with a correlation coefficient R of 96.3%. Water is completely desorbed from SAPO-34 at 155 °C, which is lower than that of 13X by 145 °C. Correlation of SAPO-34 structure to its adsorption/desorption behavior would provide fundamentals in developing high efficiency adsorbent for adsorption refrigeration system.
Heterogeneous nucleation in multi-component vapor on a partially wettable charged conducting particle. I. Formulation of general equations: Electrical surface and line excess quantities
Authors: Noppel M. , Vehkamäki H. , Winkler P. M. , Kulmala M. , Wagner P. E.
Published: October 2013

Thermodynamics is applied to formulate general equations for internal energies and grand potential for a system consisting of a dielectric liquid nucleus of a new phase on a charged insoluble conducting sphere within a uniform macroscopic one- or multicomponent mother phase. The currently available model for ion-induced nucleation assumes complete spherical symmetry of the system, implying that the seed ion is immediately surrounded by the condensing liquid from all sides. We take a step further and treat more realistic geometries, where a cap-shaped liquid cluster forms on the surface of the seed particle. To take into account spontaneous polarization of surface layer molecules we introduce the electrical surface and line excess quantities.
Heterogeneous nucleation in multi-component vapor on a partially wettable charged conducting particle. II. The generalized Laplace, Gibbs-Kelvin, and Young equations and application to nucleation
Authors: Noppel M. , Vehkamäki H. , Winkler P. M. , Kulmala M. , Wagner P. E.
Published: October 2013

Based on the results of a previous paper [M. Noppel, H. Vehkamäki, P. M. Winkler, M. Kulmala, and P. E. Wagner, J. Chem. Phys. 139, 134107 (2013)], we derive a thermodynamically consistent expression for reversible or minimal work needed to form a dielectric liquid nucleus of a new phase on a charged insoluble conducting sphere within a uniform macroscopic one- or multicomponent mother phase. The currently available model for ion-induced nucleation assumes complete spherical symmetry of the system, implying that the seed ion is immediately surrounded by the condensing liquid from all sides. We take a step further and treat more realistic geometries, where a cap-shaped liquid cluster forms on the surface of the seed particle. We derive the equilibrium conditions for such a cluster. The equalities of chemical potentials of each species between the nucleus and the vapor represent the conditions of chemical equilibrium. The generalized Young equation that relates contact angle with surface tensions, surface excess polarizations, and line tension, also containing the electrical contribution from triple line excess polarization, expresses the condition of thermodynamic equilibrium at three-phase contact line. The generalized Laplace equation gives the condition of mechanical equilibrium at vapor-liquid dividing surface: it relates generalized pressures in neighboring bulk phases at an interface with surface tension, excess surface polarization, and dielectric displacements in neighboring phases with two principal radii of surface curvature and curvatures of equipotential surfaces in neighboring phases at that point. We also re-express the generalized Laplace equation as a partial differential equation, which, along with electrostatic Laplace equations for bulk phases, determines the shape of a nucleus. We derive expressions that are suitable for calculations of the size and composition of a critical nucleus (generalized version of the classical Kelvin-Thomson equation).
Chemical sputtering of graphite by low temperature nitrogen plasmas at various substrate temperatures and ion flux densities
Authors: Bystrov K. , Morgan T. W. , Tanyeli I. , De Temmerman G. , van de Sanden M. C. M.
Published: October 2013

We report measurements of chemical sputtering yields of graphite exposed to low temperature nitrogen plasmas. The influence of surface temperature and incoming ion energy on the sputtering yields has been investigated in two distinct ion flux density regimes. Sputtering yields grow consistently with increasing temperatures in experiments with low flux density (Γi≈1020 m−2s−1−1021 m−2s−1) and high flux density (Γi≈1023 m−2s−1). Moreover, empirical fitting of the data suggests that the temperature of 670 °C is optimal for chemical sputtering at high flux density. Negative biasing of the samples was used to vary the ion energy in the low flux density regime. The sputtering yield in this case increases from 0.07 atoms/ion for Ei = 1.5 eV to 0.19 atoms/ion for Ei = 35 eV. After taking into account the dependence of the yields on temperature and ion energy, we evidenced a flux dependence of sputtering, similar to that found for chemical sputtering of carbon by hydrogen.
Origins of electrochemical performance of olivine phosphate as cathodes in Li-ion batteries: Charge transfer, spin-state, and structural distortion
Authors: Bhowmik Arghya , Sarkar Tanmay , Kumar Varanasi Arun , Waghmare Umesh V. , Dixit Bharadwaj Mridula
Published: October 2013

We use first-principles density functional theory based calculations and topological analysis of the electronic charge density in lithiated and delithiated forms of olivine phosphates (LiMPO4), an important class of cathode materials for Li-ion batteries, to determine the electronic mechanisms that govern their electrochemical potential and related properties. While electron charge transfer from Li to oxygen is known to be responsible for electrochemical properties of Li-transition metal oxides commonly used as cathodes in Li-ion batteries, the electrochemical performance of olivine phosphates involves two additional mechanisms: the spin state of transition metal (M) as stabilized by the Hund's rule and structural distortion. LiNiPO4 exhibits the highest electrochemical potential among M = Mn, Fe, Co, and Ni, owing to the largest charge transfer to oxygen orbitals located at the Fermi energy. The lowest electrochemical potential of LiFePO4 is associated with extra stability of the high-spin d5 state in its delithiated form. While the electrochemical potential for LiMnPO4/LiFePO4/LiNiPO4 or LiFePO4/LiCoPO4/LiNiPO4 generally correlates with the charge transfer from Li to oxygen, that of LiMnPO4 and LiCoPO4 shows anti-correlation. This is because the electrochemical potential of LiMnPO4 is reduced by the energy lowering structural distortion of MnPO4. We confirm the local stability of the delithiated structures of the four phosphates through calculation of phonons, supporting the possibility of their fully charged state.
A unifying mode-coupling theory for transport properties of electrolyte solutions. I. General scheme and limiting laws
Authors: Contreras Aburto Claudio , Nägele Gerhard
Published: October 2013

We develop a general method for calculating conduction-diffusion transport properties of strong electrolyte mixtures, including specific conductivities, steady-state electrophoretic mobilities, and self-diffusion coefficients. The ions are described as charged Brownian spheres, and the solvent-mediated hydrodynamic interactions (HIs) are also accounted for in the non-instantaneous ion atmosphere relaxation effect. A linear response expression relating long-time partial mobilities to associated dynamic structure factors is employed in our derivation of a general mode coupling theory (MCT) method for the conduction-diffusion properties. A simplified solution scheme for the MCT method is discussed. Analytic results are obtained for transport coefficients of pointlike ions which, for very low ion concentrations, reduce to the Deby-Falkenhagen-Onsager-Fuoss limiting law expressions. As an application, an unusual non-monotonic concentration dependence of the polyion electrophoretic mobility in a mixture of two binary electrolytes is discussed. In addition, leading-order extensions of the limiting law results are derived with HIs included. The present method complements a related MCT method by the authors for the electrolyte viscosity and shear relaxation function [C. Contreras-Aburto and G. Nägele, J. Phys.: Condens. Matter 24, 464108 (2012)], so that a unifying scheme for conduction-diffusion and viscoelastic properties is obtained. We present here the general framework of the method, illustrating its versatility for conditions where fully analytic results are obtainable. Numerical results for conduction-diffusion properties and the viscosity of concentrated electrolytes are presented in Paper II [C. Contreras Aburto and G. Nägele, J. Chem. Phys. 139, 134110 (2013)].
A unifying mode-coupling theory for transport properties of electrolyte solutions. II. Results for equal-sized ions electrolytes
Authors: Aburto Claudio Contreras , Nägele Gerhard
Published: October 2013

On the basis of a versatile mode-coupling theory (MCT) method developed in Paper I [C. Contreras Aburto and G. Nägele, J. Chem. Phys. 139, 134109 (2013)], we investigate the concentration dependence of conduction-diffusion linear transport properties for a symmetric binary electrolyte solution. The ions are treated in this method as charged Brownian spheres, and the solvent-mediated ion-ion hydrodynamic interactions are accounted for also in the ion atmosphere relaxation effect. By means of a simplified solution scheme, convenient semi-analytic MCT expressions are derived for the electrophoretic mobilities, and the molar conductivity, of an electrolyte mixture with equal-sized ions. These expressions reduce to the classical Debye-Falkenhagen-Onsager-Fuoss results in the limit of very low ion concentration. The MCT expressions are numerically evaluated for a binary electrolyte, and compared to experimental data and results by another theoretical method. Our analysis encloses, in addition, the electrolyte viscosity. To analyze the dynamic influence of the hydration shell, the significance of mixed slip-stick hydrodynamic surface boundary conditions, and the effect of solvent permeability are explored. For the stick boundary condition employed in the hydrodynamic diffusivity tensors, our theoretical results for the molar conductivity and viscosity of an aqueous 1:1 electrolyte are in good overall agreement with reported experimental data for aqueous NaCl solutions, for concentrations extending even up to two molar.
Phase field method for nonequilibrium dynamics of reversible self-assembly systems
Authors: Freed Karl F.
Published: October 2013

Phase field methods are extended to describe the nonequilibrium dynamics of reversible self-assembly systems, an extension that is complicated by the mutual coupling of many non-conserved order parameters into a set of highly nonlinear partial differential equations. Further complications arise because the sum of all non-conserved order parameters equals a conserved order parameter. The theory is developed for the simplest model of reversible self-assembly in which no additional constraints are imposed on the self-assembly process since the extension to treat more complex self-assembly models is straightforward. Specific calculations focus on the time evolution of the cluster size distribution for a free association system that is rapidly dropped from one ordered state to a more ordered state within the one-phase region. The dynamics proceed as expected, thereby providing validation of the theory which is also capable of treating systems with spatial inhomogeneities.
The asymmetric simple exclusion process with an open boundary
Authors: Tracy Craig A. , Widom Harold
Published: October 2013

We consider the asymmetric simple exclusion process confined to the nonnegative integers with an open boundary at 0. The point 0 is connected to a reservoir where particles are injected and ejected at prescribed rates subject to the exclusion rule. We derive formulas for the transition probability as a function of time from states where initially there are m particles to states where there are n particles.
Combinatorial search of superconductivity in Fe-B composition spreads
Authors: Jin Kui , Suchoski Richard , Fackler Sean , Zhang Yi , Pan Xiaoqing , Greene Richard L. , Takeuchi Ichiro
Published: October 2013

We have fabricated Fe-B thin film composition spreads in search of possible superconducting phases following a theoretical prediction by Kolmogorov et al. [Phys. Rev. Lett. 105, 217003 (2010)]. Co-sputtering was used to deposit spreads covering a large compositional region of the Fe-B binary phase diagram. A trace of superconducting phase was found in the nanocrystalline part of the spread, where the film undergoes a metal to insulator transition as a function of composition in a region with the average composition of FeB2. The resistance drop occurs at 4 K, and a diamagnetic signal has also been detected at the same temperature. From the field-dependent resistive transition behavior, we estimate the upper critical field to be approximately 2 T.
Repulsive interactions between dislocations and overgrown v-shaped defects in epitaxial GaN layers
Authors: Weidlich P. H. , Schnedler M. , Eisele H. , Dunin-Borkowski R. E. , Ebert Ph.
Published: October 2013

The spatial distribution and the projected line directions of dislocations intersecting a cross-sectional (101¯0) cleavage plane of a GaN(0001) epitaxial layer is mapped using scanning tunneling microscopy. The data is correlated with the spatial positions of v-shaped defects. The dislocations are found to be bent away from the inclined semipolar facets of v-shaped defects, due to a strain-induced repulsive interaction. The dislocation distribution is characterized by agglomerations and intersecting bundles of dislocations with parallel projected line directions, stabilized by many body effects in the repulsive strain interactions.