Operando STM study of the interaction of imidazolium-based ionic liquid with graphite

Understanding interactions at the interfaces of carbon with ionic liquids (ILs) is crucially beneficial for the diagnostics and performance improvement of electrochemical devices containing carbon as active materials or conductive additives in electrodes and ILs as solvents or additives in electrolytes. The interfacial interactions of three typical imidazolium-based ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (AMImTFSI) ILs having ethyl (C2), butyl (C4) and octyl (C8) chains in their cations, with highly oriented pyrolytic graphite (HOPG) were studied in-situ by electrochemical scanning tunneling microscopy (EC-STM). The etching of HOPG surface and the exfoliation of graphite/graphene flakes as well as cation intercalation were observed at the HOPG/C2MImTFSI interface. The etching also takes place in C4MImTFSI at −1.5 V vs Pt but only at step edges with a much slower rate, whereas C8MIm+ cations adsorbs strongly on the HOPG surface under similar conditions with no observable etching or intercalation. The EC-STM observations can be explained by the increase in van der Waals interaction between the cations and the graphite surface with increasing length of alkyl chains

A mutagenicity and cytotoxicity study on Limonium effusum aqueous extracts by Allıum, ames and MTT tests

Nowadays plants or plant extracts have become very important for alternative medicine. Plants and their extracts have many therapeutical advantages but some of them are potentially toxic, mutagenic, carcinogenic and teratogenic. Root, stem and leaf parts of Limonium effusum were used in this study and this species is an endemic species for Turkey. Mutagenic and cytotoxic effects of root, stem and leaf aqueous extracts were observed with Allium, Ames and MTT tests. Allium root growth inhibition test and mitotic index studies showed that aqueous extracts have dose-dependent toxic effects. Chromosome aberration studies indicated that especially sticky chromosome, anaphase-telophase disorder and laggard chromosome anomalies were highly observed. Ames test performed with Limonium effusum root aqueous extracts, showed weak mutagenic effects in Salmonella typhimurium TA98 strain with S9. MTT test based on mitochondrial activity indicated that most of the aqueous extracts have cytotoxic effects. This study aimed to determine the possible mutagenic and cytotoxic effects of L. effusum aqueous extracts by using bacterial, plant and mammalian cells. This research showed that some low concentrations of the L. effusum extracts have inhibited cytotoxic effects but high concentrations have induced cytotoxicity. On the other hand only a weak mutagenic activity was identified by Ames test with TA98 S9(+).В настоящее время растения или экстракты растений стали очень важными для альтернативной медицины. Растения и их экстракты имеют много терапевтических преимуществ, однако некоторые из них являются потенциально токсичными, мутагенными, канцерогенными и тератогенными. Корни, стебли и листья Limonium effusum, эндемичного вида Турции, были изучены в этой работе. Мутагенные и цитотоксические эффекты водных экс-трактов корней, стеблей и листьев Limonium effusum были изучены с помощью Allium-теста, теста Эймса и МТТ-теста. Тест на ингибирование роста корней лука и определение митотического индекса показали, что водные экстракты имеют дозозависимый токсичный эффект. При изучении хромосомных аберраций обнаружено большое количество таких аномалий, как слипшиеся хромосомы, нарушения анафазы-телофазы и отставшие хромосомы. Тест Эймса, проведенный на водных экстрактах корней Limonium effusum, показал слабо выраженный мутагенный эффект по отношению к Salmonella typhimurium, штамм TA98 с S9. МТТ-тест, основанный на митохондриальной активности, показал, что большинство экстрактов имели цитотоксические эффекты. Цель этого исследования изучить возможные мутагенные и цитотоксические эффекты водных экстрактов L. effusum с использованием бактериальных, растительных клеток и клеток млекопитающих. Определенные низкие концентрации экстрактов L. effusum ингибировали цитотоксические эффекты, а высокие концентрации индуцировали цитотоксичность. Слабая мутагенная активность была определена только при помощи теста Эймса с TA98 S9(+)

Dynamics of commitment and contribution quality in collaborative communities

It is well-known that commitment is an important ingredient for contributions of high quality. With the internet heading towards being an actionable social space, rather than a collection of web-sites, the issue of quality becomes crucial for sharing knowledge and action in collaborative scenarios. We propose a case study for the investigation of the influence of time, user feedback and interface complexity on contribution quality. We plan to exploit different online user groups across two different temporal phases for the evaluation

Residual Stress State of X65 Pipeline Girth Welds before and after Local and Furnace Post Weld Heat Treatment

This research investigated the effects of global (in other words, furnace-based) and local post weld heat treatment (PWHT) on residual stress (RS) relaxation in API 5L X65 pipe girth welds. All pipe spools were fabricated using identical pipeline production procedures for manufacturing multipass narrow gap welds. Nondestructive neutron diffraction (ND) strain scanning was carried out on girth welded pipe spools and strain-free comb samples for the determination of the lattice spacing. All residual stress measurements were carried out at the KOWARI strain scanning instrument at the Australian Nuclear Science and Technology Organization (ANSTO). Residual stresses were measured on two pipe spools in as-welded condition and two pipe spools after local and furnace PWHT. Measurements were conducted through the thickness in the weld material and adjacent parent metal starting from the weld toes. Besides, three line-scans along pipe length were made 3 mm below outer surface, at pipe wall midthickness, and 3 mm above the inner surface. PWHT was carried out for stress relief; one pipe was conventionally heat treated entirely in an enclosed furnace, and the other was locally heated by a flexible ceramic heating pad. Residual stresses measured after PWHT were at exactly the same locations as those in as-welded condition. Residual stress states of the pipe spools in as-welded condition and after PWHT were compared, and the results were presented in full stress maps. Additionally, through-thickness residual stress profiles and the results of one line scan (3 mm below outer surface) were compared with the respective residual stress profiles advised in British Standard BS 7910 “Guide to methods for assessing the acceptability of flaws in metallic structures” and the UK nuclear industry's R6 procedure. The residual stress profiles in as-welded condition were similar. With the given parameters, local PWHT has effectively reduced residual stresses in the pipe spool to such a level that it prompted the thought that local PWHT can be considered a substitute for global PWHT.</jats:p

Dynamic connectivity algorithms for Monte Carlo simulations of the random-cluster model

We review Sweeny's algorithm for Monte Carlo simulations of the random cluster model. Straightforward implementations suffer from the problem of computational critical slowing down, where the computational effort per edge operation scales with a power of the system size. By using a tailored dynamic connectivity algorithm we are able to perform all operations with a poly-logarithmic computational effort. This approach is shown to be efficient in keeping online connectivity information and is of use for a number of applications also beyond cluster-update simulations, for instance in monitoring droplet shape transitions. As the handling of the relevant data structures is non-trivial, we provide a Python module with a full implementation for future reference.Comment: Contribution to the "XXV IUPAP Conference on Computational Physics" proceedings; Corrected equation 3 and error in the maximal number of edge level

A20 Prevents Inflammasome-Dependent Arthritis by Inhibiting Macrophage Necroptosis Through Its ZnF7 Ubiquitin-Binding Domain

Deficiency in the deubiquitinating enzyme A20 causes severe inflammation in mice, and impaired A20 function is associated with human inflammatory diseases. A20 has been implicated in negatively regulating NF-κB signalling, cell death and inflammasome activation; however, the mechanisms by which A20 inhibits inflammation in vivo remain poorly understood. Genetic studies in mice revealed that its deubiquitinase activity is not essential for A20 anti-inflammatory function. Here we show that A20 prevents inflammasome-dependent arthritis by inhibiting macrophage necroptosis and that this function depends on its zinc finger 7 (ZnF7). We provide genetic evidence that RIPK1 kinase-dependent, RIPK3-MLKL-mediated necroptosis drives inflammasome activation in A20-deficient macrophages and causes inflammatory arthritis in mice. Single-cell imaging revealed that RIPK3-dependent death caused inflammasome-dependent IL-1β release from lipopolysaccharide-stimulated A20-deficient macrophages. Importantly, mutation of the A20 ZnF7 ubiquitin binding domain caused arthritis in mice, arguing that ZnF7-dependent inhibition of necroptosis is critical for A20 anti-inflammatory function in vivo

Negatively Charged In-Plane and Out-Of-Plane Domain Walls with Oxygen-Vacancy Agglomerations in a Ca-Doped Bismuth-Ferrite Thin Film.

The interaction of oxygen vacancies and ferroelectric domain walls is of great scientific interest because it leads to different domain-structure behaviors. Here, we use high-resolution scanning transmission electron microscopy to study the ferroelectric domain structure and oxygen-vacancy ordering in a compressively strained Bi0.9Ca0.1FeO3-δ thin film. It was found that atomic plates, in which agglomerated oxygen vacancies are ordered, appear without any periodicity between the plates in out-of-plane and in-plane orientation. The oxygen non-stoichiometry with δ ≈ 1 in FeO2-δ planes is identical in both orientations and shows no preference. Within the plates, the oxygen vacancies form 1D channels in a pseudocubic [010] direction with a high number of vacancies that alternate with oxygen columns with few vacancies. These plates of oxygen vacancies always coincide with charged domain walls in a tail-to-tail configuration. Defects such as ordered oxygen vacancies are thereby known to lead to a pinning effect of the ferroelectric domain walls (causing application-critical aspects, such as fatigue mechanisms and countering of retention failure) and to have a critical influence on the domain-wall conductivity. Thus, intentional oxygen vacancy defect engineering could be useful for the design of multiferroic devices with advanced functionality

Negatively Charged In-Plane and Out-Of-Plane Domain Walls with Oxygen-Vacancy Agglomerations in a Ca-Doped Bismuth-Ferrite Thin Film.

The interaction of oxygen vacancies and ferroelectric domain walls is of great scientific interest because it leads to different domain-structure behaviors. Here, we use high-resolution scanning transmission electron microscopy to study the ferroelectric domain structure and oxygen-vacancy ordering in a compressively strained Bi0.9Ca0.1FeO3-δ thin film. It was found that atomic plates, in which agglomerated oxygen vacancies are ordered, appear without any periodicity between the plates in out-of-plane and in-plane orientation. The oxygen non-stoichiometry with δ ≈ 1 in FeO2-δ planes is identical in both orientations and shows no preference. Within the plates, the oxygen vacancies form 1D channels in a pseudocubic [010] direction with a high number of vacancies that alternate with oxygen columns with few vacancies. These plates of oxygen vacancies always coincide with charged domain walls in a tail-to-tail configuration. Defects such as ordered oxygen vacancies are thereby known to lead to a pinning effect of the ferroelectric domain walls (causing application-critical aspects, such as fatigue mechanisms and countering of retention failure) and to have a critical influence on the domain-wall conductivity. Thus, intentional oxygen vacancy defect engineering could be useful for the design of multiferroic devices with advanced functionality

Synthesis of Mesoporous Silica@Co–Al Layered Double Hydroxide Spheres: Layer-by-Layer Method and Their Effects on the Flame Retardancy of Epoxy Resins

Hierarchical mesoporous silica@Co–Al layered double hydroxide (m-SiO2@Co–Al LDH) spheres were prepared through a layer-by-layer assembly process, in order to integrate their excellent physical and chemical functionalities. TEM results depicted that, due to the electrostatic potential difference between m-SiO2 and Co–Al LDH, the synthetic m-SiO2@Co–Al LDH hybrids exhibited that m-SiO2 spheres were packaged by the Co–Al LDH nanosheets. Subsequently, the m-SiO2@Co–Al LDH spheres were incorporated into epoxy resin (EP) to prepare specimens for investigation of their flame-retardant performance. Cone results indicated that m-SiO2@Co–Al LDH incorporated obviously improved fire retardant of EP. A plausible mechanism of fire retardant was hypothesized based on the analyses of thermal conductivity, char residues, and pyrolysis fragments. Labyrinth effect of m-SiO2 and formation of graphitized carbon char catalyzed by Co–Al LDH play pivotal roles in the flame retardance enhancement