Showing papers on "Valency published in 2014"

A New Water Oxidation Catalyst: Lithium Manganese Pyrophosphate with Tunable Mn Valency

Abstract: The development of a water oxidation catalyst has been a demanding challenge for the realization of overall water-splitting systems. Although intensive studies have explored the role of Mn element in water oxidation catalysis, it has been difficult to understand whether the catalytic capability originates mainly from either the Mn arrangement or the Mn valency. In this study, to decouple these two factors and to investigate the role of Mn valency on catalysis, we selected a new pyrophosphate-based Mn compound (Li2MnP2O7), which has not been utilized for water oxidation catalysis to date, as a model system. Due to the monophasic behavior of Li2MnP2O7 with delithiation, the Mn valency of Li2-xMnP2O7 (x = 0.3, 0.5, 1) can be controlled with negligible change in the crystal framework (e.g., volume change ∼1%). Moreover, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, ex-situ X-ray absorption near-edge structure, galvanostatic charging–discharging, and cyclic voltammetry analysi...

Three-dimensional valency mapping in ceria nanocrystals.

Abstract: Using electron tomography combined with electron energy loss spectroscopy (EELS), we are able to map the valency of the Ce ions in CeO2–x nanocrystals in three dimensions. Our results show a clear facet-dependent reduction shell at the surface of ceria nanoparticles; {111} surface facets show a low surface reduction, whereas at {001} surface facets, the cerium ions are more likely to be reduced over a larger surface shell. Our generic tomographic technique allows a full 3D data cube to be reconstructed, containing an EELS spectrum in each voxel. This possibility enables a three-dimensional investigation of a plethora of material-specific physical properties such as valency, chemical composition, oxygen coordination, or bond lengths, triggering the synthesis of nanomaterials with improved properties.

Mixed valency and site-preference chemistry for cerium and its compounds: A predictive density-functional theory study

Abstract: Cerium and its technologically relevant compounds are examples of anomalous mixed valency, originating from two competing oxidation states---itinerant ${\mathrm{Ce}}^{4+}$ and localized ${\mathrm{Ce}}^{3+}$. Under applied stress, anomalous transitions are observed but not well understood. Here we treat mixed valency as an ``alloy'' problem involving two valences with competing and numerous site-occupancy configurations. We use density-functional theory with Hubbard U (i.e., DFT+U) to evaluate the effective valence and predict properties, including controlling the valence by pseudoternary alloying. For Ce and its compounds, such as $(\mathrm{Ce},\mathrm{La}{)}_{2}(\mathrm{Fe},\mathrm{Co}{)}_{14}\mathrm{B}$ permanent magnets, we find a stable mixed-valent $\ensuremath{\alpha}$ state near the spectroscopic value of ${\ensuremath{ u}}_{s}=3.53$. Ce valency in compounds depends on its steric volume and local chemistry. For La doping, Ce valency shifts towards $\ensuremath{\gamma}$-like ${\mathrm{Ce}}^{3+}$, as expected from steric volume; for Co doping, valency depends on local Ce-site chemistry and steric volume. Our approach captures the key origins of anomalous valency and site-preference chemistry in complex compounds.

Coarse-grained simulations of an ionic liquid-based capacitor: I. Density, ion size, and valency effects.

Abstract: We introduce a hierarchy of generic coarse-grained models of ionic liquids of increasing complexity. We use them in molecular dynamics simulations to study the differential capacitance of a capacitor consisting of an ionic liquid between two planar electrodes. The primary goal is to explain the complex dependence of the differential capacitance Cd on the electrode potential U in simple terms, e.g. in terms of the size and valency of the ions. For this purpose we introduce the symmetric model A, which qualitatively reproduces the Cd(U) dependence predicted by the mean-field theory but also reveals strong quantitative deviations. We further introduce size asymmetry in model A by increasing the cation size. In model B we vary the cation valency, keeping the sizes of both ions constant. We show that simultaneous increases in size and valency may compensate for each other, leading to a Cd(U) very similar to that for the symmetric case. We interpret distinct features in Cd(U) on the basis of the density profiles of the ions and charge density profiles. We focus on the first two ion layers at the electrode, and demonstrate that the polarization of the ionic liquid proceeds through replacement of one ion type by the other, in contrast to the simple increase in ion concentrations typical for dilute systems. The understanding gained for the simple models serves as a reference for interpretation of complex effects of ion size, valency and shape. This is carried through in part II (a separate article) where we show how the planar shape of ions in model C brings new features to the Cd(U) curve and also to the polarization mechanism.

NaCu6Se4: A Layered Compound with Mixed Valency and Metallic Properties

Abstract: A new ternary compound NaCu6Se4 was synthesized from the reaction of Cu in a molten sodium polyselenide flux. The compound crystallizes in trigonal space group R3m with a = 4.0465(3) A and c = 41.493(5) A. The crystal structure contains flat two-dimensional slabs of (1)/∞[Cu6Se4] with a unique structural arrangement, separated by Na cations. The compound contains mixed valency and has a high conductivity of ∼3 × 10(3) S cm(-1) at room temperature, and exhibits increasing conductivity with decreasing temperature, indicating metallic behavior. A small positive thermopower (4-11 μV K(-1) from 300 to 500 K) and Hall effect measurements indicate p-type transport with a carrier concentration of ∼2.8(3) × 10(21) cm(-3) and a hole mobility of ∼8.75 cm(2) V(-1) s(-1) at 300 K. NaCu6Se4 exhibits temperature-independent Pauli paramagnetism.

Synergetic Properties of Chinese Verb Valency

Abstract: This paper analyses the 500 most frequent verbs in contemporary Chinese and investigates their synergetic properties. The results show that the rank-frequency distributions of both valency and polysemy abide by a power-law distribution and that valency and polysemy of these verbs abide by the Good distribution and the positive negative binomial distribution respectively. Statistical analysis indicates that the greater valency a verb has, the greater polysemy, frequency and polytextuality can be expected. To find a suitable unit of measurement, strokes, a feature of the Chinese writing system, and pinyin, a phonemic transcription system of Chinese, are introduced in the present study to measure word length. These two types of word length correlate highly with each other, and both exhibit some inverse interrelations with other linguistic variables like verb valency, polysemy, frequency and polytextuality. Finally, based on these findings, we present a synergetic model (control cycle) of Chinese verb...

Arc-transitive graphs of valency 8 have a semiregular automorphism

Abstract: One version of the polycirculant conjecture states that every vertex-transitive graph has a non-identity semiregular automorphism that is, a non-identity automorphism whose cycles all have the same length. We give a proof of the conjecture in the arc-transitive case for graphs of valency 8, which was the smallest open valency.

Bivalent Verb Classes in the Languages of Europe: A Quantitative Typological Study

Abstract: The aims of this study are twofold: to propose methods for measuring (dis)similarities in the organization of valency class systems across languages, and to test them on a sample of European languages in order to reveal areal and genetic patterns. The data were gathered for 29 languages using a questionnaire containing 130 contextualized uses of bivalent predicates. The properties under study include (i) lexical range of transitives, (ii) lexical range of valency frames defined in terms of the “locus” of non-transitivity (whether A or P arguments are encoded by oblique devices), (iii) overall complexity of valency class systems, and (iv) lexical distribution of verbs among valency classes. In case of the simpler properties (i)–(iii), maps with quantified isoglosses and pairwise comparison of languages based on Hamming distance are used. For (iv) these methods are inapplicable (valency classes cannot be equated across languages), and I propose a distance metric based on entropy and pairwise mutual information between distributions. The distance matrices are analyzed using the NeighborNet algorithm as implemented in SplitsTree. I argue that more holistic properties of valency class systems are indicative of large areal effects: e.g., many western European languages (Germanic, Romance, Basque and some Balkan languages) are lexically “most transitive” in Europe. Low-level areal signal is clearly discernible in the data on more subtle aspects of the organization of valency classes. The findings imply that distributions of verbs into valency classes can develop quickly and are transferable in contact situations, despite drastic dissimilarities in argument-coding devices.

Chapter 2. Special valency behavior of Czech deverbal nouns

Abstract: This chapter provides an in-depth analysis of the valency properties of Czech deverbal nouns. It focuses on the forms of complementation they take. These can be typical, related to those of the source verbs, or special, without any relationship to them. We present an overview of these special shifts in valency. Special forms of participants have an impact on the syntactic behavior of the noun and its meaning. We argue that it is not always a plain shift in meaning but sometimes only a slight meaning nuance. Such nouns with special forms of participants require creating a new valency frame; they represent a separate category on the boundary between syntactic and lexical derivation.

EngVallex - English Valency Lexicon

Abstract: EngVallex is the English counterpart of the PDT-Vallex valency lexicon, using the same view of valency, valency frames and the description of a surface form of verbal arguments. EngVallex contains links also to PropBank and Verbnet, two existing English predicate-argument lexicons used, i.a., for the PropBank project. The EngVallex lexicon is fully linked to the English side of the PCEDT parallel treebank, which is in fact the PTB re-annotated using the Prague Dependency Treebank style of annotation. The EngVallex is available in an XML format in our repository, and also in a searchable form with examples from the PCEDT.

First-principles study of valence and structural transitions in EuO under pressure

Abstract: The electronic structure of EuO under pressure is studied using the self-interaction corrected local spin density approximation. EuO, which at ambient conditions crystallizes in the NaCl (B1) structure, is predicted to undergo an isostructural insulator to metal transition at 48 GPa. This transition is associated with a change of valence from a divalent to an intermediate valent state, with the resulting effective valency of 2.35. The pressure range between 48 and 70 GPa is characterized by the competition between an intermediate valent B1 structured phase and a CsCl (B2) structured phase where both the divalent and intermediate valence configurations are in play. Eventually, at pressures above 70 GPa, the intermediate valent B2 phase prevails. The effective Eu valence in the B2 intermediate valence phase is around 2.28, i.e., a decrease in effective valence occurs. This scenario is in line with the reentrant valence behavior observed in recent pressure experiments.

Anionogenic mixed valency in KxBa1-xO2-δ.

Abstract: We have synthesized members of an isostructural solid solution series KxBa1-xO2-δ (x < 0.41, δ < 0.11) containing mixed-valent dioxygen anions. Synthesis in liquid ammonia solution allows a continuous range of compounds to be prepared. X-ray and neutron diffraction show that KxBa1-xO2-δ adopts the tetragonal rocksalt-derived structure of the end members KO2 and BaO2, without any structural phase transition down to 5 K, the lowest temperature studied here. We identify four oxygen-oxygen stretching modes above 750 cm(-1) in the measured Raman spectra, unlike the spectra of KO2 and BaO2 which both contain just a single mode. We use density functional theory calculations to show that the stretching modes in KxBa1-xO2-δ arise from in-phase and anti-phase coupling of the stretching of nearest-neighbor oxygen dimers when the valence state of the dimers lies between -1 and -2 because of mixed cation coordination. This coupling is a direct signature of a novel type of anionogenic mixed valency.

Valency classes in Xârâcùù (New Caledonia)

Abstract: This article provides an overview of valency classes and valency alternations in Xârâcuu1 and tries to describe the main developments which are still perceivable and which explain the great variety and some of the specificities found in Xârâcuu verb classes. Xârâcuu is spoken by about 6000 people living in the Canala and Thio areas of the Mainland of New Caledonia, and belongs to the Southern subgroup of New Caledonian, itself one of the main subgroups of Oceanic, which is part of the Austronesian language family.

Chapter 1. Contribution of valency to the analysis of language

Abstract: The main criteria used for the valency of verbs in the framework of Functional Generative Description (FGD) are introduced, leading to the recognition of three classes of verbal modifications : inner participants (IPs), obligatory free modifications (FMs), and quasivalency modifiers (QMs). The sources of surface deletions of valency modifications are presented. For an analysis of noun valency, word formation is taken into consideration. The criteria proposed for the valency of verbs are applied in order to determine the valency of deverbal nouns. Conversion of the verbal valency frame into the valency frame of the noun is accompanied by formal changes in the morphemic form of inner participants. The behavior of specific noun modifiers is studied with regard to their position in the corresponding valency frame (VF).

To Pay or to Get Paid: Enriching a Valency Lexicon with Diatheses

Abstract: Valency lexicons typically describe only unmarked usages of verbs (the active form); however, verbs prototypically enter different surface structures. In this paper, we focus on the so-called diatheses, i.e., the relations between different surface syntactic manifestations of verbs that are brought about by changes in the morphological category of voice, e.g., the passive diathesis. The change in voice of a verb is prototypically associated with shifts of some of its valency complementations in the surface structure. These shifts are implied by changes in morphemic forms of the involved valency complementations and are regular enough to be captured by syntactic rules. However, as diatheses are lexically conditioned, their applicability to an individual lexical unit of a verb is not predictable from its valency frame alone. In this work, we propose a representation of this linguistic phenomenon in a valency lexicon of Czech verbs, VALLEX, with the aim to enhance this lexicon with the information on individual types of Czech diatheses. In order to reduce the amount of necessary manual annotation, a semi-automatic method is developed. This method draws evidence from a large morphologically annotated corpus, relying on grammatical constraints on the applicability of individual types of diatheses.

Valency Frames in a Hungarian Corpus

Abstract: In this paper, we investigate the relationship between the number of frames, the length and the frequency of verbs in Hungarian, based on data gathered from the short business news sub-corpus of the Szeged Dependency Treebank. We hypothesize that the most frequent verbs have the most valency frames, the shortest verbs are the most frequent ones and the shortest verbs have the most valency frames. We extend our investigations to full valency frames as well, where arguments and adjuncts are treated in the same way. We also compare the valency frames gathered from the treebank to those found in a valency lexicon constructed on a theoretical basis. Our results support the above hypotheses in the case of valency frames and full valency frames as well.

Valenz, Konstruktion und Lernerwörterbuch

Abstract: The contribution covers three related topics: 1. addressees of valency dictionaries and possible situations of dictionary use; 2. the value of constructions in language learning with a discussion of the construction grammar of Adele Goldberg; 3. a short presentation of two valency entries for an English learner dictionary of German.

Mekanisme penaikan valensi bahasa bali dialek nusa penida (bbdnp)

Abstract: This article will be concerned with verbal construction in BBDNP. The construction discussed about causatives verb formation. Causativation is related to valency changes of verb. The concept of valence referes to the number of argument that a head may take, in this case the head is the predicate of a clause. Causativation can increase the valence of a verb. Causative processes involve affixes which will be attached on a particular verb. According to this article, affixes of valenecy changes are causative suffix {-ang} and causative suffix {-in}. Both of them mark the BBDNP base, such as a verb, an adjective, a precategorial even state verb. In other side, suffix {-a} can decrease valence of the verb.

Three dimensional valency mapping in CeO$_{2-x}$ nanocrystals

Abstract: Using electron tomography in combination with spatially resolved electron energy-loss spectroscopy at high energy resolution, we are able to map the valency of the Ce ions in CeO$_{2-x}$ nanocrystals. Our three-dimensional results show a clear facet-dependent reduction shell at the surface of ceria nanoparticles; {111} surface facets show a low surface reduction, whereas at {001} surface facets the cerium ions are more likely to be reduced over a larger surface shell. The novelty of this generic tomographic technique is that it allows a full three dimensional datacube to be reconstructed, containing a full electron energy-loss spectrum in each voxel. The ability to extract an electron energy-loss spectrum in each point of a reconstructed datacube, enables the three-dimensional investigation of a plethora of material-specific physical properties such as valency, chemical composition, oxygen coordination or bond lengths. These experiments will trigger the synthesis of nanomaterials with improved properties and the design of nanostructures with novel functionalities.

The effects of input-enhanced and output-enhanced grammar instruction on the learning of English verb tenses and relative clauses

Abstract: The present study investigated whether different types of form-focused instruction, input-enhanced or output-enhanced, might be effective in improving low-proficiency learners' English knowledge about specific linguistic forms. The participants were 111 first-year Korean university students enrolled in an English conversation course. They were assigned to three groups; 35 students in the input-enhanced group (TIE), 33 in the output-enhanced group (DICT), and 45 in the control group (CG). English verb tenses and relative clauses were selected as the target structures. Pre- and post-tests were conducted to measure the effectiveness of different types of form-focused instruction on the acquisition of the target forms. Pre- and post-questionnaires were administered to examine the extent of the students' perceptions and attitudes towards the English instruction that they received. The study discovered that both input-enhanced and output-enhanced instruction were more effective than traditional grammar instruction in developing grammatical knowledge about verb tenses, while output-enhanced instruction was more effective than input-enhanced and traditional grammar instruction with respect to the learning of relative clauses. The results of the questionnaires indicated that learners who performed the TIE task and the dictogloss task showed positive changes in their perceptions about the English instruction that they received; only those in the dictogloss task showed positive changes in their attitudes towards the instruction. Based on the results, the limitations of the study and the pedagogical implications are provided.

Variation in verb cluster interruption

Abstract: Except for finite verbs in main clauses, verbs in Standard Dutch cluster together in a clause-final position. In certain Dutch dialects, non-verbal material can occur within this verb cluster (Verhasselt 1961; Koelmans 1965, among many others). These dialects vary with respect to which types of elements can interrupt the verb cluster, varying from particles to various types of arguments and adverbs (Barbiers, van der Auwera, Bennis, Boef, de Vogelaer & van der Ham 2008). A study amongst forty Dutch dialect speakers reveals an ordered ranking of grammatical types, reflecting their acceptability in a verb cluster. I argue that this ranking directly follows from syntactic principles: The syntactic size and position of the intervening element affect its acceptance in a verb cluster. Potentially, these principles interact with a preference of performance dubbed ‘minimize domains’ (Hawkins 1994, 2003, 2004), which requires both the higher verb and the intervening element to be adjacent to the main verb, leading to two conflicting structures.

Investigating iron ion distribution in (Y3 − xCax)3Fe5)12 garnets as a function of Ca2+ content

Abstract: Ferrite garnets have special physical properties associated with the valence of obtained ions. These properties can be studied only by precise structural analysis and the determining the ions’ valency.

What Makes the Strengths of Construction Grammar

Abstract: The paper starts with a sketch of the strengths of Construction Grammar. Then it has two sections for illustration of how CG widens the scope of grammar studies,maintaining that CG helps solve hard grammar nuts like lexico-semantic attribution,verb valency( vicious circle),agentivity-patientivity issues with existential constructions,semantic issues with VO constructions,parts of speech and so on. This is followed by elaboration of how CG replenishes other grammars( eg. Generative Grammar) which is exemplified by instances of complementation between interpretations by light verb and by"quantitative-relation construction",and is also exemplified by the powerful "BE-to construction"analysis of Goldberg in contrast to Word Grammar and Functional Grammar among other things.

Verb Sense Classification

Abstract: This document addresses the verb sense disambiguation (VSD) problem, a sub-problem of word sense disambiguation (WSD), for European Portuguese. It aims at developing a set of modules of an existing Natural Language Processing (NLP) system, which will enable it to choose adequately the precise sense that a verb features in a given sentence, from among other, potential different meanings. This paper presents various methods used in supervised classification that can be adopted on VSD, and it discusses the main problems found for this task, briefly describing the techniques previously used to address it, as well as the new Machine Learning (ML) techniques that will be integrated in the STRING system. These ML techniques were tested in several scenarios to determine the impact of different features. The baseline accuracy of 63.86% results from the most frequent sense (MFS) for each verb lemma in a set of 24 verbs. Among the ML techniques tested, the best method was the Naive Bayes algorithm, which achieved an accuracy of 67.71%, a gain of 3.85% above

Crystal Structure of Yb2CuGe6 and Yb3Cu4Ge4 and the Valency of Ytterbium.

Abstract: Single crystals of Yb2CuGe6 (I) and Yb3Cu4Ge4 (II) are prepared by melting of the elements in a Y/Cu/Ge molar ratio of 3:2:6 and 3:3:6, resp., in an indium flux (alumina crucible in evacuated silica tube, 850 °C, 2 d, slow cooling).