Distinct Valence Research Articles

Motivation to Think and Order Effects in Persuasion: The Moderating Role of Chunking

Two studies examined the hypothesis that chunking—defined as the degree to which information is grouped into explicitly labeled categories of distinct valence—moderates the impact of motivation to think on order effects in persuasion. Studies 1 and 2 examined motivation to think in terms of perceived personal relevance and need for cognition, respectively. In both studies, participants read arguments for and against a hypothetical exam policy. These arguments were presented in varying orders and in either a chunked or an unchunked format. Results were consistent with the predictions: Under chunked conditions, participants who were highly motivated to think were more susceptible to primacy effects than were those low in motivation to think. Under unchunked conditions, this pattern was reversed—those highly motivated to think were more susceptible to recency effects than those low in motivation to think.

(Bi0.4Sr0.45Co0.15)Sr2CoO5−δ: a new 1201-type oxygen dependent series of cobaltites

A new series of cobaltites (Bi0.4Sr0.45Co0.15)Sr2CoO5−δ (0.15≤δ≤0.55) related to the 1201-type structure, has been synthesized. The X-ray and neutron powder diffraction studies, coupled with transmission electron microscopy (TEM) observations, evidence an orthorhombic cell (Pnnn, a≈b≈2ap, c≈2c1201) for the lowest oxygenated phases, whereas a tetragonal cell (I4/mmm, a=b≈ap2, c≈2c1201) is observed for the highest ones. The main structural feature of this series deals with the ordering between Bi3+(Co3+) and Sr2+ within the rocksalt layer [(Bi/Co,Sr)O]∞ leading to the doubling of the c1201 parameter. The structural transition, observed versus oxygen content, is correlated to a specific oxygen arrangement around cobalt species. The XANES investigations carried out for two limit oxygen contents, 4.53 and 4.85, show two distinct formal cobalt valences. These materials have a semi-conducting behavior with negative magnetoresistance properties which are sensitive to their oxygen content. In particular, for the tetragonal phase, a spin glass like behavior (Tcusp=38.5 K) has been observed.

Tuning chemotactic responses with synthetic multivalent ligands

Background: Multivalent ligands have been used previously to investigate the role of ligand valency and receptor clustering in eliciting biological responses. Studies of multivalent ligand function, however, typically have employed divalent ligands or ligands of undefined valency. How cells respond to multivalent ligands of distinct valencies, which can cluster a signaling receptor to different extents, has never been examined. The chemoreceptors, which mediate chemotactic responses in bacteria, are localized, and clustering has been proposed to play a role in their function. Using multivalent ligands directed at the chemoreceptors, we hypothesized that we could exploit ligand valency to control receptor occupation and clustering and, ultimately, the cellular response. Results: To investigate the effects of ligand valency on the bacterial chemotactic response, we generated a series of linear multivalent arrays with distinct valencies by ring-opening metathesis polymerization. We report that these synthetic ligands elicit bacterial chemotaxis in both Escherichia coli and Bacillus subtilis. The chemotactic response depended on the valency of the ligand; the response of the bacteria can be altered by varying chemoattractant ligand valency. Significantly, these differences in chemotactic responses were related to the ability of the multivalent ligands to cluster chemoreceptors at the plasma membrane. Conclusions: Our results demonstrate that ligand valency can be used to tune the chemotactic responses of bacteria. This mode of regulation may arise from changes in receptor occupation or changes in receptor clustering or both. Our data implicate changes in receptor clustering as one important mechanism for altering cellular responses. Given the diverse events modulated by changes in the spatial proximity of cell surface receptors, our results suggest a general strategy for tuning biological responses.

Spin-singlet clusters in the ladder compound NaV2O5

The space group of alpha(')-NaV2O5 turns below T(c) = 34 K from Pmmn with all V sites equivalent, into Fmm2 with three independent vanadium sites per layer. This is incompatible with models of charge ordering into V4+ and V5+. Our structure determination indicates that the phase transition consists of a charge ordering with three distinct valence states, formally V4+, V4.5+, and V5+. The singlet formation is not associated with dimerization on the spin ladder, but with the formation of spin clusters. Finally, we ascribe the quadrupling of the c axis to the large polarizability of the V2O5 skeleton.

Effect of anion relaxation on charge transfer processes in organic conductors

A mixed Valence-Bond/Hartree-Fock (VB/HF) method was developped in order to calculate the coulombic and transfer extended Hubbard type parameters between conduction electrons in organic conductors. The coulombic terms are obtained by comparison of the differences in the energies of the distinct Valence Bond electronic configurations and the corresponding terms of an effective electronic Hamiltonian derived from the Pariser-Parr-Pople Hamiltonian [1–2]. The transfer integrals are directly identifiable with the extra-diagonal terms of the effective Hamiltonian matrix built onto the different VB configurations [3]. The present work proposes a model so as to incorporate the effect of anions relaxation in the calculation of the Hamiltonian matrix elements.

Control of Hole Distribution and Superconducting Properties in Bi_(2)Sr_(2)(Ca_(1-x)Y_(x))Cu_(2)O_(8+delta)

The dependence of H{sub irr} on the concentration and distribution of holes in the Bi{sub 2}Sr{sub 2}(Ca{sub 1{minus}x}Y{sub x})Cu{sub 2}O{sub 8+{delta}} (Bi-2212) system was investigated. Coulometric Cu(I)/(II) and Fe(II)/(III) titrations were applied to determine oxygen contents and distinct Cu and Bi valences and to thereby estimate the hole distribution among the SrO-Bi{sub 2}O{sub 2+{delta}}SrO and (Ca{sub 1{minus}x}Y{sub x})Cu{sub 2}O{sub 4} blocks. With increasing Y-substitution level, x, continuous increase in the oxygen content and decrease in the thickness of the SrO-Bi{sub 2}O{sub 2+{delta}}-SrO blocking block were observed. The extra oxygen taken in the structure only partially counteracts the trivalent-Y to divalent-Ca substitution, and consequently the hole concentration in both blocks was found to decrease. With increasing x and {delta}, H{sub irr} was not enhanced but rather depressed. This suggests that the thickness of the blocking block is not primary parameter in determining the H{sub irr}.

Environmental Monitoring of Chromium in Air, Soil, and Water

Historical uses of chromium have resulted in its widespread release into the environment. In recent years, a significant amount of research has evaluated the impact of chromium on human health and the environment. Additionally, numerous analytical methods have been developed to identify and quantitate chromium in environmental media in response to various state and federal mandates such as CERCLA, RCRA, CWA, CAA, and SWDA. Due to the significant toxicity differences between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium, it is essential that chromium be quantified in these two distinct valence states to assess the potential risks to exposure to each in environmental media. Speciation is equally important because of their marked differences in environmental behavior. As the knowledge of risks associated with each valence state has grown and regulatory requirements have evolved, methods to accurately quantitate these species at ever-decreasing concentrations within environmental media have also evolved. This paper addresses the challenges of chromium species quantitation and some of the most relevant current methods used for environmental monitoring, including ASTM Method D5281 for air, SW-846 Methods 3060A, 7196A and 7199 for soils, sediments, and waste, and U.S. EPA Method 218.6 for water.

Cerium intermetallic compounds with two inequivalent crystallographic sites

The low-temperature properties of five cerium intermetallic compounds, Ce 2Sn 5, CePtGe 2, Ce 5Ni 6In 11 and Ce 4− x Ru 4Ge 12+ x (with x = 0 and 1), which have two inequivalent cerium lattice sites, have been measured. The first three behave as trivalent systems at high temperatures (> 50 K) but at low temperatures they exhibit some unusual properties because of the different kinds of cerium-cerium interactions, including heavy fermion, intermediate valence and magnetic order. The Ce 4− x Ru 4Ge 12+ x system is unusual and displays a variety of behaviors such as heavy fermion, magnetic and non-magnetic atom disorder (MAD/NMAD) spin glass, and both tri- and tetravalency. The existence of independent trivalent and tetravalent cerium atoms in an intermetallic phase is unique and as far as we are aware this is the first time such a distinct valence situation has been reported for a cerium compound. Other cerium systems with multi-cerium sites reported by others are also briefly discussed.

Alcohol and human emotion: A multidimensional analysis incorporating startle-probe methodology.

The effect of alcohol intoxication on emotional response was investigated using a model of emotion that includes both arousal and valence dimensions. Thirty-six university students were exposed to multiple presentations of photographic slides selected to elicit distinctive emotional reactions ranging from very pleasant to very unpleasant; half of them received a moderate (approximately .75 ml/kg) dose of ethanol. The students' psychophysiological responses indicated that both general startle reactivity and autonomic indices specific to emotional arousal were diminished by alcohol. However, the affective modulation of startle, occurring with emotional states manipulated by slides with distinct valences, remained intact. These findings suggest that stress-response dampening by alcohol may involve a nonspecific attenuation of arousal reactions evident for positive as well as negative stimuli and that theories of motivation for drinking that are based on mood alteration may need refinement. Language: en

Alcohol and human emotion: a multidimensional analysis incorporating startle-probe methodology.

The effect of alcohol intoxication on emotional response was investigated using a model of emotion that includes both arousal and valence dimensions. Thirty-six university students were exposed to multiple presentations of photographic slides selected to elicit distinctive emotional reactions ranging from very pleasant to very unpleasant; half of them received a moderate (approximately .75 ml/kg) dose of ethanol. The students' psychophysiological responses indicated that both general startle reactivity and autonomic indices specific to emotional arousal were diminished by alcohol. However, the affective modulation of startle, occurring with emotional states manipulated by slides with distinct valences, remained intact. These findings suggest that "stress-response dampening" by alcohol may involve a nonspecific attenuation of arousal reactions evident for positive as well as negative stimuli and that theories of motivation for drinking that are based on mood alteration may need refinement.

Gating charge differences between two voltagegated K + channels are due to the specific charge content of their respective S4 regions

Voltage-gated ion channels that differ in their primary amino acid sequence in the putative voltage sensor, the S4 region, show distinct voltage-sensing characteristics. In this study, we directly compared two voltage-gated K + channels, the mammalian RCK1 with the Drosophila Shab11, and correlated the specific amino acid content of their respective S4 regions with the distinct voltagesensing properties they exhibit. We find that specific differences in the charge content of the S4 region are sufficient to account for the distinct gating valence of each channel. However, differences in residues inside the S4 region are not sufficient to account for each channel's characteristic voltage range of activation.

Valence studies on various superconducting bismuth and lead cuprates and related materials

The oxygen contents and metal valences have been determined in various (Bi, Pb) 2Sr 2(Ca, Y)Cu 2O z , Bi 2Sr 2Ca 2Cu 3O z and Pb 2(Ba, Y, Ca) 3Cu 3O z samples by a two-step coulometric titration method. The first titration experiment, which consists of the reactions of Cu(III), Bi(V) and Pb(IV) with CuCl followed by an anodic oxidation of the excess Cu(I), reveals the oxygen content of the sample. In the second experiment the valences of bismuth and lead are distinguished from the Cu-valence by taking advantage of the reaction with Fe(II). By performing the first experiment without adding CuCl it was even possible to evaluate the distinct valence values for crystallographically different copper atoms when the sample contained both Cu(III) and Cu(I) in separate layers. The applicability of the employed analysis procedures as well as the results obtained for the studied materials are discussed.

Influence of WCl 6-based catalytic systems on polypentenamer microstructure

The microstructure of polypentenamer resulting from cyclopentene polymerization initiated by two types of WCl 6-based catalytic systems has been determined from the 13C NMR spectrum. Ternary catalysts containing organoaluminium compounds as cocatalysts ( e.g. WCl 6-epichlorohydrini-Bu 3Al) lead mostly to polypentenamers of predominant trans configuration. However the nature of the activator affects the polymer microstructure; this microstructure was correlated with the reducing ability of the organoaluminium compound and the electron donor, and the acceptor ability of the activator. In contrast, the binary catalyst containing organotin as cocatalyst (WCl 6-Ph 4Sn) yields essentially polypentenamer of mainly cis configuration at −20 °C, the cis content falling at higher temperature. Analysis of double-bond pair sequences in the polymer obtained with the above catalysts showed a non-Bemoullian distribution for cis contents greater than 30%. Determination of the oxidation states of W in the active species by ceriometric titrations indicated different valency states for the two types of catalyst; the different microstructures of the polymer were correlated with these distinct valencies of the W atom. The above results are interpreted in terms of a metallacarbene-metallacy do butane mechanism; the main stereochemical features of the ringopening polymerization of cyclopentene using the two types of catalyst are outlined. The essential role of the oxidation state of the W atom for reaction stereochemistry is pointed out.

Sunset and Flowers: The Sexual Dimension of Foi Spatial Organization

This paper analyzes the structure of Foi ideology concerning space and motion. It is argued that to describe Foi spatiality one must not only consider how they symbolically construe cardinality; one must also examine the kinds of motion that link their various points of spatial orientation. This motion is not merely geographic, but also encompasses the social movements represented by marriage, death, and widow remarriage. It is demonstrated that Foi rituals of maiden and widow marriage encompass their spatial orientation and are phrased in the idioms of motion between cardinal points. These cardinal points thus have distinct sexual valences in Foi thought, since their marriage rituals are basically denotative of intersexual definition and mediation.

An algorithm for the construction of the graphs of organic molecules

A description and a formal proof of an efficient computer implemented algorithm for the construction of graphs is presented. This algorithm, which is part of a program for the automated analysis of organic compounds, constructs all of the non-isomorphic, connected multi- graphs based on a given degree sequence of nodes and which arise from a relatively small “catalog” of certain canonical graphs. For the graphs of the more common organic molecules, a catalog of most of the canonical graphs is known, and the algorithm can produce all of the distinct valence isomers of these organic molecules.