Thermal stability study of nitrogen functionalities in a graphene network

Catalyst-free vertically aligned graphene nanoflakes possessing a large amount of high density edge planes were functionalized using nitrogen species in a low energy N+ ion bombardment process to achieve pyridinic, cyanide and nitrogen substitution in hexagonal graphitic coordinated units. The evolution of the electronic structure of the functionalized graphene nanoflakes over the temperature range 20-800^{\circ}C was investigated in situ, using high resolution x-ray photoemission spectroscopy. We demonstrate that low energy irradiation is a useful tool for achieving nitrogen doping levels up to 9.6 at.%. Pyridinic configurations are found to be predominant at room temperature, while at 800^{\circ}C graphitic nitrogen configurations become the dominant ones. The findings have helped to provide an understanding of the thermal stability of nitrogen functionalities in graphene, and offer prospects for controllable tuning of nitrogen doping in device applications.Comment: Corresponding author: [email protected]

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Electrocatalytic Hydrogen Evolution Reaction on Edges of a Few Layer Molybdenum Disulfide Nanodots

The design and development of inexpensive highly efficient electrocatalysts for hydrogen production, underpins several emerging clean-energy technologies. In this work, for the first time, molybdenum disulfide (MoS2) nanodots have been synthesized by ionic liquid assisted grinding exfoliation of bulk platelets and isolated by sequential centrifugation. The nanodots have a thickness of up to 7 layers (4 nm) and an average lateral size smaller than 20 nm. Detailed structural characterization established that the nanodots retained the crystalline quality and low oxidation states of the bulk material. The small lateral size and reduced number of layers provided these nanodots with an easier path for the electron transport and plentiful active sites for the catalysis of hydrogen evolution reaction (HER) in acidic electrolyte. The MoS2 nanodots exhibited good durability and a Tafel slope of 61 mVdec-1 with an estimated onset potential of -0.09 V vs RHE, which are considered among the best values achieved for 2H phase. It is envisaged that this work may provide a simplistic route to synthesize a wide range of 2D layered nanodots that have applications in water splitting and other energy related technologies. KEYWORDS: MoS2 nanosheets, hydrogen evolution reaction, electrocatalysis, edges, nanodots, ionic liquid exfoliation, water splittingComment: Corresponding author: [email protected]. in ACS Applied Materials and Interfaces, 201

A new integrated model for multitasking during web searching

Investigating multitasking information behaviour, particularly while using the web, has become an increasingly important research area. People s reliance on the web to seek and find information has encouraged a number of researchers to investigate the characteristics of information seeking behaviour and the web seeking strategies used. The current research set out to explore multitasking information behaviour while using the web in relation to people s personal characteristics, working memory, and flow (a state where people feel in control and immersed in the task). Also investigated were the effects of pre-determined knowledge about search tasks and the artefact characteristics. In addition, the study also investigated cognitive states (interactions between the user and the system) and cognitive coordination shifts (the way people change their actions to search effectively) while multitasking on the web. The research was exploratory using a mixed method approach. Thirty University students participated; 10 psychologists, 10 accountants and 10 mechanical engineers. The data collection tools used were: pre and post questionnaires, pre-interviews, a working memory test, a flow state scale test, audio-visual data, web search logs, think aloud data, observation, and the critical decision method. Based on the working memory test, the participants were divided into two groups, those with high scores and those with lower scores. Similarly, participants were divided into two groups based on their flow state scale tests. All participants searched information on the web for four topics: two for which they had prior knowledge and two more without prior knowledge. The results revealed that working memory capacity affects multitasking information behaviour during web searching. For example, the participants in the high working memory group and high flow group had a significantly greater number of cognitive coordination and state shifts than the low working memory group and low flow group. Further, the perception of task complexity was related to working memory capacity; those with low memory capacity thought task complexity increased towards the end of tasks for which they had no prior knowledge compared to tasks for which they had prior knowledge. The results also showed that all participants, regardless of their working memory capacity and flow level, had the same the first frequent cognitive coordination and cognitive state sequences: from strategy to topic. In respect of disciplinary differences, accountants rated task complexity at the end of the web seeking procedure to be statistically less significant for information tasks with prior knowledge compared to the participants from the other disciplines. Moreover, multitasking information behaviour characteristics such as the number of queries, web search sessions and opened tabs/windows during searches has been affected by the disciplines. The findings of the research enabled an exploratory integrated model to be created, which illustrates the nature of multitasking information behaviour when using the web. One other contribution of this research was to develop new more specific and closely grounded definitions of task complexity and artefact characteristics). This new research may influence the creation of more effective web search systems by placing more emphasis on our understanding of the complex cognitive mechanisms of multitasking information behaviour when using the web

ANXIETY DISORDERS AND THE FREQUENCY OF NEGATIVE THOUGHTS: A COMPARATIVE STUDY IN CHILDREN WITH AND WITHOUT SPECIAL LEARNING DISABILITIES

Special Learning Disabilities (SLD) are often accompanied by negative thoughts of self-assessment, deficits in social interactions and psycho-emotional problems as well, which hinder the development and the smooth integration of children diagnosed with SLD into their environment. This research attempts to investigate the association of negative self-assessment thoughts and anxiety disorders with Special Learning Disabilities in a sample of sixty Greek-speaking children in 4th, 5th and 6th grades with and without SLD, including their parents. The tools used for this purpose are the Children’s Automatic Thoughts Scale (CATS), and the Spence Children’s Anxiety Scale (SCAS-CH) self-report questionnaire, which assess anxiety disorders. Parents were asked to answer the corresponding Spence Children’s Anxiety Scale-Parents Edition (SCAS-P) symptom-monitoring questionnaire. According to the results compared to their normal development peers, children with SLD had a higher incidence of negative thoughts, which is more likely to lead to symptoms of anxiety disorders; their parents in fact were able to perceive the severity or frequency of these symptoms in their children. In addition, the frequency of negative thoughts and symptoms related to anxiety disorders seemed to be influenced by the student’s condition (with or without SLD), but not by gender and age.   Article visualizations

Donor-acceptor graphene-based hybrid materials for managing photoinduced electrontransfer reactions

Graphene research and in particular the topic of chemical functionalization has been exploded in the last decade. The main aim is to induce solubility and thereby enhance processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. In this frame, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets, soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. Some donor-acceptor hybrid materials with photo- and/or electro-active components were prepared and characterized, while their charge-transfer properties were evaluated. However, it was obvious that the highly defected framework of graphene oxide cannot be really utilized in applications that are governed by charge-transfer processes, for example in solar cells. The alternative route for solubilizing and modifying graphene by exfoliating graphite is the current method of choice for the realization of novel hybrid materials and further boost their direct applicability in artificial photosynthesis and the construction of photovoltaic devices. In this review article, the routes for obtaining donor-acceptor graphene-based hybrid materials for managing charge-transfer phenomena, mainly, but not exclusively, with porphyrins and phthalocyanines are presented. Earlier examples and studies performed on graphene oxide modified with organic electron donors are also given

Towards an Integrated Model for Breast Cancer Etiology: The Crucial Role of the Number of Mammary Tissue-Specific Stem Cells

Perinatal events and conditions, notably birth weight, are associated with breast cancer risk in offspring, and correlates of mammary gland mass are predictors of breast cancer risk. These findings may be interpreted as indicating that high levels of estrogens and components of the insulin-like growth factor system during pregnancy favour the generation of mammary tissue-specific stem cells, and that the number of these cells, which is positively associated with mammary gland mass, is an important determinant of breast cancer risk. Perinatal events and conditions may also affect risk for other malignancies, but the evidence in the case of breast cancer is prominent, possibly because estrogens and the insulin-like growth factor system are both involved in breast cancer etiology and affect birth weight

Enhancing Cryptosporidium parvum recovery rates for improved water monitoring

AbstractWater monitoring is essential to ensure safe drinking water for consumers. However existing methods have several drawbacks, particularly with regard to the poor recovery of Cryptosporidium due to the inability to efficiently elute Cryptosporidium oocysts during the established detection process used by water utilities. Thus the development of new inexpensive materials that could be incorporated into the concentration and release stage that would control Cryptosporidium oocysts adhesion would be beneficial. Here we describe improved filter performance following dip-coating of the filters with a “bioactive” polyacrylate. Specifically 69% more oocysts were eluted from the filter which had been coated with a polymer than on the naked filter alone

Controllable selective exfoliation of high-quality graphene nanosheets and nanodots by ionic liquid assisted grinding

Bulk quantities of graphene nanosheets and nanodots have been selectively fabricated by mechanical grinding exfoliation of natural graphite in a small quantity of ionic liquids. The resulting graphene sheets and dots are solvent free with low levels of naturally absorbed oxygen, inherited from the starting graphite. The sheets are only two to five layers thick. The graphene nanodots have diameters in the range of 9-29 nm and heights in the range of 1-16 nm, which can be controlled by changing the processing time.Comment: * Corresponding authors: [email protected]; [email protected]