29 research outputs found

    Fast Ionic Conductivity in the Most Lithium-Rich Phosphidosilicate Li14SiP6.

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    Solid electrolytes with superionic conductivity are required as a main component for all-solid-state batteries. Here we present a novel solid electrolyte with three-dimensional conducting pathways based on "lithium-rich" phosphidosilicates with ionic conductivity of σ > 10-3 S cm-1 at room temperature and activation energy of 30-32 kJ mol-1 expanding the recently introduced family of lithium phosphidotetrelates. Aiming toward higher lithium ion conductivities, systematic investigations of lithium phosphidosilicates gave access to the so far lithium-richest compound within this class of materials. The crystalline material (space group Fm3m), which shows reversible thermal phase transitions, can be readily obtained by ball mill synthesis from the elements followed by moderate thermal treatment of the mixture. Lithium diffusion pathways via both tetrahedral and octahedral voids are analyzed by temperature-dependent powder neutron diffraction measurements in combination with maximum entropy method and DFT calculations. Moreover, the lithium ion mobility structurally indicated by a disordered Li/Si occupancy in the tetrahedral voids plus partially filled octahedral voids is studied by temperature-dependent impedance and 7Li NMR spectroscopy

    The Temporal Dynamics of Voluntary Emotion Regulation

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    Background: Neuroimaging has demonstrated that voluntary emotion regulation is effective in reducing amygdala activation to aversive stimuli during regulation. However, to date little is known about the sustainability of these neural effects once active emotion regulation has been terminated. Methodology/Principal Findings: We addressed this issue by means of functional magnetic resonance imaging (fMRI) in healthy female subjects. We performed an active emotion regulation task using aversive visual scenes (task 1) and a subsequent passive viewing task using the same stimuli (task 2). Here we demonstrate not only a significantly reduced amygdala activation during active regulation but also a sustained regulation effect on the amygdala in the subsequent passive viewing task. This effect was related to an immediate increase of amygdala signal in task 1 once active emotion regulation has been terminated: The larger this peak postregulation signal in the amygdala in task 1, the smaller the sustained regulation effect in task 2. Conclusions/Significance: In summary, we found clear evidence that effects of voluntary emotion regulation extend beyond the period of active regulation. These findings are of importance for the understanding of emotion regulation i

    Changes in Prefrontal-Limbic Function in Major Depression after 15 Months of Long-Term Psychotherapy

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    Neuroimaging studies of depression have demonstrated treatment-specific changes involving the limbic system and regulatory regions in the prefrontal cortex. While these studies have examined the effect of short-term, interpersonal or cognitive-behavioural psychotherapy, the effect of long-term, psychodynamic intervention has never been assessed. Here, we investigated recurrently depressed (DSM-IV) unmedicated outpatients (N = 16) and control participants matched for sex, age, and education (N = 17) before and after 15 months of psychodynamic psychotherapy. Participants were scanned at two time points, during which presentations of attachment-related scenes with neutral descriptions alternated with descriptions containing personal core sentences previously extracted from an attachment interview. Outcome measure was the interaction of the signal difference between personal and neutral presentations with group and time, and its association with symptom improvement during therapy. Signal associated with processing personalized attachment material varied in patients from baseline to endpoint, but not in healthy controls. Patients showed a higher activation in the left anterior hippocampus/amygdala, subgenual cingulate, and medial prefrontal cortex before treatment and a reduction in these areas after 15 months. This reduction was associated with improvement in depressiveness specifically, and in the medial prefrontal cortex with symptom improvement more generally. This is the first study documenting neurobiological changes in circuits implicated in emotional reactivity and control after long-term psychodynamic psychotherapy

    Exploring the effects of target-language extramural activities on students’ written production

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    Frequent engagement in English extramural activities (i.e., activities that take place outside the classroom) has been found to have a positive impact on EFL learners’ vocabulary knowledge and reading comprehension. In the present study, we aim to extend our knowledge of the possible impact of extramural activities into the realm of second-language writing. Specifically, we investigate the relationship among a number of English extramural activities and two aspects of writing development: lexical diversity and noun phrase complexity. The data are drawn from the Swedish Learner English Corpus (SLEC) which includes texts produced by Swedish secondary school students. The corpus also includes information on how many hours per week students (i) engage in conversations in English, (ii) communicate in English while playing computer/video games, (iii) read in English, (iv) spend time on social media with English content, (v) and watch TV shows or movies in English. The results show that reading in English leads to higher frequency of adjectival modification, whereas conversing in English and watching TV programs positively impact lexical diversity. The results of the study have implications for discussions about the role of L2 classroom instruction vis-à-vis learners’ extramural activities

    Exploiting features of adenovirus replication to support mammalian kinase production

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    Faced with the current wealth of genomic data, it is essential to have robust and reliable methods of converting DNA sequences into their functional gene products. We demonstrate here that when conditions are established that take advantage of the replication-associated virus amplification, the virus-induced shutdown of host protein synthesis as well as the activation of signalling pathways that normally occur during virus replication, adenovirus biology can be exploited to generate a potent kinase expression system. Residual virus in the protein production has always been a limitation for adenovirus systems and we describe a DNA intercalator/ultraviolet light treatment that eliminates residual adenovirus in protein preparations that has no deleterious effect on enzyme activity. The use of mammalian cells in combination with adenovirus generated a variety of active enzymes which could not be produced in Escherichia coli or baculovirus-infected insect cells. Thus, the utility of adenovirus-mediated enzyme expression as a versatile alternative to established protein production technologies is demonstrated

    Synthesis and Characterization of the Lithium-Rich Phosphidosilicates Li<sub>10</sub>Si<sub>2</sub>P<sub>6</sub> and Li<sub>3</sub>Si<sub>3</sub>P<sub>7</sub>

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    The lithium phosphidosilicates Li<sub>10</sub>Si<sub>2</sub>P<sub>6</sub> and Li<sub>3</sub>Si<sub>3</sub>P<sub>7</sub> are obtained by high-temperature reactions of the elements or including binary Li–P precursors. Li<sub>10</sub>Si<sub>2</sub>P<sub>6</sub> (<i>P</i>2<sub>1</sub>/<i>n</i>, <i>Z</i> = 2, <i>a</i> = 7.2051(4) Å, <i>b</i> = 6.5808(4) Å, <i>c</i> = 11.6405(7) Å, β = 90.580(4)°) features edge-sharing SiP<sub>4</sub> double tetrahedra forming [Si<sub>2</sub>P<sub>6</sub>]<sup>10–</sup> units with a crystal structure isotypic to Na<sub>10</sub>Si<sub>2</sub>P<sub>6</sub> and Na<sub>10</sub>Ge<sub>2</sub>P<sub>6</sub>. Li<sub>3</sub>Si<sub>3</sub>P<sub>7</sub> (<i>P</i>2<sub>1</sub>/<i>m</i>, <i>Z</i> = 2, <i>a</i> = 6.3356(4) Å, <i>b</i> = 7.2198(4) Å, <i>c</i> = 10.6176(6) Å, β = 102.941(6)°) crystallizes in a new structure type, wherein SiP<sub>4</sub> tetrahedra are linked via common vertices and which are further connected by polyphosphide chains to form unique <sub>∞</sub><sup>2</sup>[Si<sub>3</sub>P<sub>7</sub>]<sup>3–</sup> double layers. The two-dimensional Si–P slabs that are separated by Li atoms can be regarded as three covalently linked atoms layers: a defect α-arsenic type layer of P atoms sandwiched between two defect wurzite-type Si<sub>3</sub>P<sub>4</sub> layers. The single crystal and powder X-ray structure solutions are supported by solid-state <sup>7</sup>Li, <sup>29</sup>Si, and <sup>31</sup>P magic-angle spinning NMR measurements

    Rapid Crystallization and Kinetic Freezing of Site-Disorder in the Lithium Superionic Argyrodite Li6PS5Br

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    Lithium argyrodite superionic conductors are currently being investigated as solid electrolytes for all-solid-state batteries. Recently, in the lithium argyrodite Li6PS5X (X = Cl, Br, I), a site-disorder between the anionsS2–and X–has been observed, which strongly affects the ionic transport and appears to be a function of the halide present. In this work, we show how such disorder in Li6PS5Br can be engineered viathe synthesis method. By comparing fast cooling (i.e. quenching) to more slowly cooled samples, we find that anion site-disorder is higher at elevated temperatures, and that fast cooling can be used to kinetically trap the desired disorder, leading to higher ionic conductivities as shown by impedance spectroscopy in combination with ab-initiomolecular dynamics. Furthermore, we observe that after milling, a crystalline lithium argyrodite can be obtained within one minute of heat treatment. This rapid crystallization highlights the reactive nature of mechanical milling and shows that long reaction times with high energy consumption are not needed in this class of materials. The fact that site-disorder induced viaquenching is beneficial for ionic transport provides an additional approach for the optimization and design of lithium superionic conductors.</p
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