ELECTROCATALYTIC PROPERTIES OF MIXED-VALENCE MOLYBDENUM OXIDE THIN-FILM MODIFIED MICROELECTRODES

A compact blue conducting mixed-valence Mo (VI,V) oxide film was grown on the surface of a carbon fibre (CF) microelectrode by cycling the potential between +0.20 and similar to 0.70 V SCE in freshly prepared Na2MoO4 solution in H2SO4 (pH 2). The thicknes

VALENCE STATE EQUILIBRIA BETWEEN COBALT AND MANGANESE IONS AND MAGNETIC-PROPERTIES OF LACO0.9MN0.1O3

According to the thermodynamic equilibria between the low spin state Co(III) (t2g6e(g)0) ion and the high spin state Co3+ (t2g4e(g)2) ion and between the cobalt and manganese ions with different valence state and spin state, an approximate semiempirical f

SPIN AND VALENCE STATE EQUILIBRIA OF COBALT AND MAGNETIC-PROPERTIES OF LACOO3

On the basis of the spin and valence state equilibria and superexchange interaction of the various cobalt ions in LaCoO3, an approximate semiempirical formula has been proposed and used to calculate magnetic susceptibilities of LaCoO3 over a wide temperature range (100-1200 K). The results indicate that there are thermodynamic equilibria between the low spin state Co(III) (t2g6e(g)0) ion, the high spin state Co3+ (t2g4e(g)2) ion, the Co(II) (t2g6e(g)1) ion and the Co(IV) (t2g5e(g)0) ion in LaCoO3. The energy difference between the low spin state Co(III) and the high spin state Co3+ is about 0.006 eV. The content of the low spin state Co(III) ion is predominant in LaCoO3 and the content of the high spin state Co3+ ion varies with temperature, reaching a maximum at about 350 K, then decreasing gradually with increasing temperature. At low temperature the contents of the Co(II) ion and the Co(IV) ion in LaCoO3 are negligible, while above 200 K the contents of both the Co(II) ion and the Co(IV) ion increase with increasing temperature; however, the content of the Co(II) ion always is larger than that of the Co(IV) ion at any temperature. These calculated results are in good agreement with experimental results of the Mossbauer effect, magnetic susceptibility and electrical conductivity of LaCoO3.

THE VALENCE CHANGE FROM RE3+ TO RE2+ (RE-EQUIVALENT-TO-EU, SM, YB) IN SRB4O7-RE PREPARED IN AIR AND THE SPECTRAL PROPERTIES OF RE2+

A valence change from RE3+ to RE2+ (RE=Eu, Sm, Yb) was observed in samples of SrB4O7: RE prepared by solid state reaction at high temperature in air. The phosphors SrB4O7: RE2+ show efficient luminescence at room temperature. The broad band d-f emissions of Eu2+ and Yb2+ are at 367 and 360 nm respectively. The sharp line f-f emissions of the Sm2+ ion (5D0-F-7(J)) are in the range 680-780 nm. The probable reasons for the valence change of Eu, Sm and Yb in this host are discussed.

VALENCE AND MAGNETIC-PROPERTIES OF YSR2-XCAXV3O9-Y

Compounds YSr22-xCaxVO9-y have an orthorhombic symmetry. XPS results show that the vanadium ions exist in the mixing valence in the system. Temperature dependence of magnetic susceptibility represents the Curie-Weiss law. The valence state of vanadium obviously affects the magnetic properties of YSr2-xCaxV3O9-y. The system exhibits a paramagnetic behavior from 300K to 1073K.

MAGNETIC-PROPERTIES OF LANTHANUM MANGANITE AND VALENCE EQUILIBRIA OF MANGANESE

The paramagnetic susceptibility of lanthanum manganite has been measured over a wide temperature range (100-1073 K). On the basis of the thermodynamic equilibria between the various manganese ions with different valence and spin states and the magnetic interactions between the various manganese ions, a semiempirical formula has been proposed to calculate the paramagnetic susceptibilities of lanthanum manganite at different temperatures. The results indicate that most of the discrepancies between the calculated and experimental reciprocal susceptibilities of lanthanum manganite are less than 10% and that the relative contents of the various manganese ions in lanthanum manganite vary with temperature. The relative content of the trivalent manganese ion with a high spin state is dominant over the whole temperature range, while be relative content of the tetravalent manganese ion with a high spin state decreases monotonously with increasing temperature. At 300 K the calculated relative content of the tetravalent manganese ion in lanthanum manganite is about 34%, which is in good agreement with the experimental result (30%). There are some divalent manganese ions present in lanthanum manganite from low temperature to high temperature. The ratio of the relative contents of the tetravalent and divalent manganese ions in the compound varies with temperature. Above 750 K the relative content of the tetravalent manganese ion is less than that of the divalent manganese ion. The variation in the electrical resistivity of lanthanum manganite with temperature has also been interpreted reasonably.

FACTOR-ANALYSIS SPECTROPHOTOMETRY FOR THE SIMULTANEOUS DETERMINATION OF VALENCE STATES OF METALS

Two M(n+)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol systems for the simultaneous determination of the valence states of Cr and Fe using factor analysis were studied. (1) At pH 4.0, Cr(III) and Cr(VI) react with the reagent to form stable complexes and a slight difference in the wavelengths of maximum absorption (lambda(max.)) between the two complexes is observed when the sodium lauryl sulfate, which also acts as a solubilizing and sensitizing agent, is added, viz., 590 nm for Cr(III) and 593 nm for Cr(VI) complexes. (2) In the presence of ethanol, both Fe(II) and Fe(III) form 1:2 complexes with the reagent at pH 2.5-3.5 and the lambda(max.) of the Fe(II) and Fe(III) complexes is at 557 and 592 nm, respectively. In the target transformation factor analysis, the K coefficients calculated from the standard mixtures by classical least-squares analysis and a non-zero intercept added to each wavelength are used as the target vector instead of the pure component standards; this can decrease the analysis errors introduced by the interaction between the two species and by deviations from Beer's law.

PREPARATION, STRUCTURE AND INFLUENCE OF VALENCE STATE ON LASR2-XCAXV3O9+/-Y

New compounds LaSr2-xCa-(x)V3O9+/-y (x = 0.0, 0.67, 1.0, 1.33 and 2.0) have been synthesized with a simple new method X ray powder diffraction results indicate that they are single compound. Their lattice constants are calculated. The structure of LaSr2-xCa(x)V39+/-y changed from cubic to orthorhombic and back to cubic with the increase of calcium content. The results of weight gain in TG and XPS curves show that vanadium with lower valent state is oxidized to higher valent state at higher temperature. The oxygen content of new compounds are calculated from the weight gain. It is shown that V3+ and V4+ may coexist in LaSr2-xCa(x)V3O9+/-y. These compounds show that low resistivity.

DYNAMIC PROCESS OF VALENCE CHANGE OF EUROPIUM ION IN EUROPIUM DIFLUORIDE AT HIGH-TEMPERATURE

The dynamic process of the ionic valence changing from Eu~(2+) to Eu~(3+) in EuF_2 at high temperature has been investigated by ESCA, high,temperature X-ray diffraction, high temperature spectrum, high temperature magnetic Isusceptibility and Mssbauer spectrum. It has been shown that the formed Eu~(3+) exists in different compounds when EuF_2 is heated to high temperature in different atmospheres. In air, Eu~(3+) exists in the form of hexagonal EuOF, in nitrogen, in the form of orthogonal EuF_3 and non-hexa...

情绪干扰下焦虑水平对执行抑制的影响机制——事件相关电位研究

Behavioral inhibition model suggests the generation of anxiety is related with over-inhibition. For knowing about anxiety better, we used event-related potential (ERP) technique to explore the underlying mechanism of executive inhibition under the emotional distracter in high and low trait-anxious groups. Firstly, we set up the Chinese affective picture system (CAPS) as the stimuli of subsequent experiments. Secondly, we screened the high and low trait-anxious participants using the State-Trait Anxiety Inventory. In the first ERP study, a modified oddball paradigm was used with the positive, neutral and negative pictures as novel stimuli and the potentials evoked by three types pictures were analyzed. In the second ERP study, the same paradigm with higher task load was employed to examine the interaction of anxious level and emotion. Main results as follows: 1. CAPS consisted of 852 pictures was assessed via three dimensionalities, valence, arousal and dominance. The standard deviation of scores on valence and dominance was more than the standard deviation of scores on dimension of arousal. Scatter plot showed that the score distributing on the dimension of valence and arousal was wide in CAPS. 2. In both high and low trait-anxiety groups, the amplitudes of N2 and P3 of negative pictures were greater and smaller respectively as compared with neutral and positive pictures, which suggested all participants no matter what anxious level required more inhibition processing to negative information than others. 3. With increasing of task load, the P3 amplitudes of negative pictures in high anxious group were reduced relative to neutral pictures. In addition, in high anxious group, the P3 amplitudes of positive pictures had the same changes as those of negative ones. Whereas, the reduced P3 of positive pictures were not observed in low anxious group. The results showed the high anxious participants employed the same inhibitory strategy to the positive distracter as the negative distracter, which possibly the over-inhibition processing was involved in this group. 4. Dipole source analysis found cingulate may be involved in executive inhibition processing. In sum, as for the inhibition, high and low anxious group both is sensitive to negative information. However, in the high load situation, due to the shortness of cognitive resources, the high anxious individual represents the general sensitivity to all emotional information. These results gave the electrophysiological evidence for over-inhibition in high trait-anxiety group.

Dealing with affective needs in e-learning: Contrasting two cases in two cultures.

This chapter presents and contrasts descriptions of two cases of online affective support provided to support students engaged in higher level learning tasks. The cases are set in different cultures, centre upon different intended learning outcomes, and follow different tutorial styles. One (Eastern) tutor acted as a “shepherd leader” in response to needs arising in the Confucian Heritage Culture as the teacher promoted critical thinking, according to the Western model. The other (Western) tutor provided Rogerian facilitation of reflective learning journals, kept by students seeking to develop personal and professional capabilities. In both styles, affective support features strongly. The cultural and pedagogical comparisons between the cases have proved useful to the writers. These distinctions together with the similarities between the two online styles emerge in the comparisons. Keywords: affective needs, asynchronous discussion, Confucian Heritage Culture, constructivism, critical thinking, facilitation, reflection, reflective learning journals, Rogerian, shepherd leadership, social-constructivist, student-centred, support.

Dynamics of learner affective development in early FLL

Affective learner factors were first considered as a cause of success in language learning. This was followed by a change in approach and recently authors (e.g., Edelenbos, Johnstone, & Kubanek, 2006) have considered them an important outcome, especially in early foreign language learning (FLL). Current research into affective learner factors in early FLL tries to catch the developmental aspects too, and studies are emerging that take a contextual view as well. This paper describes a study on affective characteristics of young FL learners that combines the developmental and contextual perspectives. Using the case study methodology the author analyses the affective profiles of three young learners of English as a foreign language who were followed for 4 years. The analyses are done taking into account their immediate language learning environment, home support, out-of-school exposure to English and language achievement. The findings suggest that affective learner factors contribute to the dynamic complexity of early FLL.

MyRoom: A user-centred model of affective responsive architecture

Can my immediate physical environment affect how I feel? The instinctive answer to this question must be a resounding “yes”. What might seem a throwaway remark is increasingly borne out by research in environmental and behavioural psychology, and in the more recent discipline of Evidence-Based Design. Research outcomes are beginning to converge with findings in neuroscience and neurophysiology, as we discover more about how the human brain and body functions, and reacts to environmental stimuli. What we see, hear, touch, and sense affects each of us psychologically and, by extension, physically, on a continual basis. The physical characteristics of our daily environment thus have the capacity to profoundly affect all aspects of our functioning, from biological systems to cognitive ability. This has long been understood on an intuitive basis, and utilised on a more conscious basis by architects and other designers. Recent research in evidence-based design, coupled with advances in neurophysiology, confirm what have been previously held as commonalities, but also illuminate an almost frightening potential to do enormous good, or alternatively, terrible harm, by virtue of how we make our everyday surroundings. The thesis adopts a design methodology in its approach to exploring the potential use of wireless sensor networks in environments for elderly people. Vitruvian principles of “commodity, firmness and delight” inform the research process and become embedded in the final design proposals and research conclusions. The issue of person-environment fit becomes a key principle in describing a model of continuously-evolving responsive architecture which makes the individual user its focus, with the intention of promoting wellbeing. The key research questions are: What are the key system characteristics of an adaptive therapeutic single-room environment? How can embedded technologies be utilised to maximise the adaptive and therapeutic aspects of the personal life-space of an elderly person with dementia?.

Affective and Experiential Influences on English Skills of Heritage Spanish Speakers

Gemstone Team GABS (Grammar Acquisition in Bilingual Students)