857 research outputs found

    Luminescent coordination polymers based on Ca²⁺ and octahedral cluster anions [{M₆Clⁱ₈}Clᵃ₆}²⁻ (M = Mo, W) : synthesis and thermal stability studies

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    Luminescent coordination polymers (CPs) based of inexpensive stable precursors are attractive materials for applications. Here we report the synthesis and evaluation of the stability and photophysical characteristics of the first examples of phosphorescent CPs based on octahedral molybdenum and tungsten cluster anions. Specifically 1D CP trans-[{Ca(OPPh₃)₄}{{M₆Clⁱ₈}Clᵃ₆}]∞ (M = Mo, W) can be obtained either directly at increased temperature or via intermediate phases [cis-Ca(OPPh₃)₄(H₂O)₂][{M₆Clⁱ₈}Clᵃ₆]∙2CH₃CN that are stable at room-temperature, but convert to the titled CP at temperatures above 100 °C

    Complexes of non-lacunary Keggin- and Dawson-type polyoxometalates with Pb(ii): formation of 1D coordination polymers with different bonding modes

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    © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.A new coordination polymer based on Keggin-type [SiW12O40]4- and Pb2+ ions, {Pb2(μ2-DMF)2(DMF)8(SiW12O40)} (1a), was prepared by a reaction between H4[SiW12O40] and Pb(NO3)2 in N,N-dimethylformamide (DMF). Varying the crystallization conditions, a complex with a slightly different coordination mode of the {Pb2} unit and solvate composition, {Pb2(μ2-DMF)2(DMF)8(SiW12O40)}·DMF (1b), can be obtained. The complex containing Well-Dawson polyoxoanions, {(Pb(μ2-DMF)3(DMF)6)(Pb(DMF)5)(P2W18O62)}·0.5DMF·1.3H2O (2), was prepared by a similar strategy

    Studies of run-away electron beams and hard x-ray emission in ISTTOK tokamak

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    The paper describes measurements of fast run-away electron beams emitted from a plasma torus in the ISTTOK tokamak, which were performed by means of a new Cherenkov-type detector equipped with four radiators made of aluminium-nitrate (AlN) crystals of 10 mm in diameter and 2.5 mm in thickness each. The measuring head was fixed to a movable support, which enabled the radiators to be placed in chosen positions along the minor radius of ISTTOK. The radiators were coated with molybdenum (Mo) layers of different thicknesses since the main aim of this study was to estimate an energy spectrum of the recorded electrons. Attention was also paid to measurements of hard X-rays emitted from ISTTOK and to their correlations with run-away electrons. The investigated correlations showed that the both emissions are strongly coupled.Описано виміри швидких втікаючих електронних пучків, що випускається з плазмового тора в токамаці ISTTOK, що було виконано за допомогою нових черенковських детекторів, оснащених чотирма радіаторами з нітратуалюмінію (AIN) із кристалами діаметром 10 і товщиною 2,5мм кожний. Вимірювальна головка була встановлена на рухливій підставі,що дозволило розміщати радіатори в обраних позиціях по малому радіусі ISTTOK. Радіатори були покриті молібденовими (Мо) шарами різної товщини ,оскільки основною метою даного дослідження було оцінити енергетичний спектр електронів, що регіструються. Увага була також приділена виміру твердого рентгенівського випромінювання з ISTTOK і його кореляції з втікаючими електронами. Досліджені кореляції показали, що обоє випромінювання сильно зв’язані.Описываются измерения быстрых убегающих электронных пучков, испускаемых из плазменного тора в токамаке ISTTOK, которые были выполнены с помощью новых черенковских детекторов, оснащенных четырьмя радиаторами из нитратаалюминия (AIN) с кристаллами диаметром 10 и толщиной 2,5 мм каждый. Измерительная головка была установлена на подвижном основании, что позволило размещать радиаторы в выбранных позициях по малому радиусу ISTTOK. Радиаторы были покрыты молибденовыми (Мо) слоями различной толщины, поскольку основной целью данного исследования было оценить энергетический спектр регистрируемых электронов. Внимание было также уделено измерению жесткого рентгеновского излучения из ISTTOK и его корреляции с убегающими электронами. Исследованные корреляции показали, что оба излучения сильно связаны

    The Rift Valley fever accessory proteins NSm and P78/NSm-GN are distinct determinants of virus propagation in vertebrate and invertebrate hosts.: Role of NSm-related proteins in RVFV infection

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    International audienceRift Valley fever virus (RVFV) is an enzootic virus circulating in Africa that is transmitted to its vertebrate host by a mosquito vector and causes severe clinical manifestations in humans and ruminants. RVFV has a tripartite genome of negative or ambisense polarity. The M segment contains five in-frame AUG codons that are alternatively used for the synthesis of two major structural glycoproteins, GN and GC, and at least two accessory proteins, NSm, a 14-kDa cytosolic protein, and P78/NSm-GN, a 78-kDa glycoprotein. To determine the relative contribution of P78 and NSm to RVFV infectivity, AUG codons were knocked out to generate mutant viruses expressing various sets of the M-encoded proteins. We found that, in the absence of the second AUG codon used to express NSm, a 13-kDa protein corresponding to an N-terminally truncated form of NSm, named NSm', was synthesized from AUG 3. None of the individual accessory proteins had any significant impact on RVFV virulence in mice. However, a mutant virus lacking both NSm and NSm' was strongly attenuated in mice and grew to reduced titers in murine macrophages, a major target cell type of RVFV. In contrast, P78 was not associated with reduced viral virulence in mice, yet it appeared as a major determinant of virus dissemination in mosquitoes. This study demonstrates how related accessory proteins differentially contribute to RVFV propagation in mammalian and arthropod hosts

    Replicating viral vector platform exploits alarmin signals for potent CD8<sup>+</sup> T cell-mediated tumour immunotherapy.

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    Viral infections lead to alarmin release and elicit potent cytotoxic effector T lymphocyte (CTL &lt;sup&gt;eff&lt;/sup&gt; ) responses. Conversely, the induction of protective tumour-specific CTL &lt;sup&gt;eff&lt;/sup&gt; and their recruitment into the tumour remain challenging tasks. Here we show that lymphocytic choriomeningitis virus (LCMV) can be engineered to serve as a replication competent, stably-attenuated immunotherapy vector (artLCMV). artLCMV delivers tumour-associated antigens to dendritic cells for efficient CTL priming. Unlike replication-deficient vectors, artLCMV targets also lymphoid tissue stroma cells expressing the alarmin interleukin-33. By triggering interleukin-33 signals, artLCMV elicits CTL &lt;sup&gt;eff&lt;/sup&gt; responses of higher magnitude and functionality than those induced by replication-deficient vectors. Superior anti-tumour efficacy of artLCMV immunotherapy depends on interleukin-33 signalling, and a massive CTL &lt;sup&gt;eff&lt;/sup&gt; influx triggers an inflammatory conversion of the tumour microenvironment. Our observations suggest that replicating viral delivery systems can release alarmins for improved anti-tumour efficacy. These mechanistic insights may outweigh safety concerns around replicating viral vectors in cancer immunotherapy
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