Search results for "klusteri"
showing 10 items of 88 documents
Towards Atomically Precise Supported Catalysts from Monolayer‐Protected Clusters: The Critical Role of the Support
2020
Abstract Controlling the size and uniformity of metal clusters with atomic precision is essential for fine‐tuning their catalytic properties, however for clusters deposited on supports, such control is challenging. Here, by combining X‐ray absorption spectroscopy and density functional theory calculations, it is shown that supports play a crucial role in the evolution of monolayer‐protected clusters into catalysts. Based on the acidic nature of the support, cluster‐support interactions lead either to fragmentation of the cluster into isolated Au–ligand species or ligand‐free metallic Au0 clusters. On Lewis acidic supports that bind metals strongly, the latter transformation occurs while pre…
Motivators, barriers and strategies of weight management: A cross-sectional study among Finnish adults.
2018
Abstract Background Weight management (WM) is an ongoing global challenge. The purpose of this study was to analyze motivators, barriers, and strategies of WM among Finnish adults. Methods Data were collected in the ‘KULUMA’ (Consumers at the Weight Management Market) project among 667 community-dwelling adults in Eastern and Central Finland (Kuopio and Jyvaskyla). The self-reported questionnaire collected background information and responses to motivators, barriers, and strategy items. Principal component analysis (PCA) was used to extract components of motivators, barriers, and strategies of WM, along with K-means clustering to categorize the participants. Results About 55% of the respond…
Patterns of Eating and Physical Activity Attitudes and Behaviors in Relation to Body Mass Index
2016
The aim of the study was to identify and characterize the patterns of the psychological and behavioral characteristics, in relation to body mass index. In addition, the study examined the associations between the patterns and demographic characteristics, exercise, eating habits, and healthrelated psychological variables. Participants were 361 Greek adults, randomly selected and completed self-reported questionnaires. The surveys examined demographic characteristics, healthrelated psychological variables (attitudes and intentions toward exercise and healthy eating, perceived behavioral control, health locus of control, general health, self-control, and body image) and the behaviors of exerci…
Prospects and challenges for computer simulations of monolayer-protected metal clusters
2021
Precise knowledge of chemical composition and atomic structure of functional nanosized systems, such as metal clusters stabilized by an organic molecular layer, allows for detailed computational work to investigate structure-property relations. Here, we discuss selected recent examples of computational work that has advanced understanding of how these clusters work in catalysis, how they interact with biological systems, and how they can make self-assembled, macroscopic materials. A growing challenge is to develop effective new simulation methods that take into account the cluster-environment interactions. These new hybrid methods are likely to contain components from electronic structure t…
A study on the fragmentation of sulfuric acid and dimethylamine clusters inside an atmospheric pressure interface time-of-flight mass spectrometer
2022
Abstract. Sulfuric acid and dimethylamine vapours in the atmosphere can form molecular clusters, which participate in new particle formation events. In this work, we have produced, measured, and identified clusters of sulfuric acid and dimethylamine using an electrospray ionizer coupled with a planar-differential mobility analyser, connected to an atmospheric pressure interface time-of-flight mass spectrometer (ESI–DMA–APi-TOF MS). This set-up is suitable for evaluating the extent of fragmentation of the charged clusters inside the instrument. We evaluated the fragmentation of 11 negatively charged clusters both experimentally and using a statistical model based on quantum chemical data. Th…
Reducing Power Consumption of Wireless Networks Through Collaborative DMC Mobile Clusters
2017
Reducing the energy consumption of the wireless network is significantly important to the economic and ecological sustainability of the ICT industry, as high energy consumption may limit the performance of wireless networks and is one of the main network costs. To solve energy consumption problem, especially on the terminal side, a scheme known as distributed mobile cloud (DMC) is considered to be a potential solution. Multiple mobile terminals (MTs) can cooperative to take advantage of good quality links among the MTs to save energy when receiving from the Base Station (BS). In this paper, we aim to find the optimal transmit power to further reduce the energy consumption of DMC. From simul…
[Cu32(PET)24H8Cl2](PPh4)2: A Copper Hydride Nanocluster with a Bisquare Antiprismatic Core
2020
Atomically precise coinage metal (Au, Ag and Cu) nanoclusters (NCs) have been the subject of immense interest for their intriguing structural, photophysical and catalytic properties. However, the synthesis of Cu NCs is highly challenging because of low reduction potential and high reactivity of copper, demonstrating the need for new synthetic methods using appropriate ligand combinations. By designing a diamine-assisted synthetic strategy, here we report the synthesis and total structure characterization of a box-like dianionic Cu NC, [Cu32(PET)24H8Cl2](PPh4)2 co-protected by 2-phenylethanethiolate (PET), hydride and chloride ligands. Its crystal structure comprises a rare bisquare antipris…
Enhanced Surface Ligands Reactivity of Metal Clusters by Bulky Ligands for Controlling Optical and Chiral Properties.
2021
Surface ligands play critical roles in determining the surface properties of metal clusters. However, modulating the properties and controlling the surface structure of clusters through surface‐capping agent displacement remain a challenge. In this work, a silver cluster, [Ag 14 (SPh(CF 3 ) 2 ) 12 (PPh 3 ) 4 (DMF) 4 ] ( Ag 14 ‐DMF , where HSPh(CF 3 ) 2 is 3,5‐bis(trifluoromethyl)benzenethiol, PPh 3 is triphenylphosphine and DMF is N,N‐Dimethylformamide), with weakly coordinated DMF ligands on the surface silver sites, was synthesized by using a mixed ligands strategy (bulky thiolates, phosphines and small solvents). The as‐prepared Ag 14 ‐DMF is a racemic mixture of chiral molecules. Owing …
Towards Evidence-Based Academic Advising Using Learning Analytics
2018
Academic advising is a process between the advisee, adviser and the academic institution which provides the degree requirements and courses contained in it. Content-wise planning and management of the student’ study path, guidance on studies and academic career support is the main joint activity of advising. The purpose of this article is to propose the use of learning analytics methods, more precisely robust clustering, for creation of groups of actual study profiles of students. This allows academic advisers to provide evidence-based information on the study paths that have actually happened similarly to individual students. Moreover, academic institutions can focus on management and upda…
Klusterointi radiotaajuuspaikannuksessa
2017
Mobiililaitteiden tarkalla paikantamisella on tärkeä rooli nykyisissä ja tulevissa langattomiin verkkoihin perustuvissa sovelluksissa. GPS-paikannus on yleisesti käytetty, mutta se suoriutuu kehnosti sisätiloissa ja saattaa ruuhkahuippujen aikana olla kykenemätön suorittamaan kaikkia paikannuspyyntöjä tehokkaasti. Mobiiliverkossa paikannus voidaan suorittaa kolmiomittauksen avulla, joka vaatii kuitenkin aktiivisen puhelun. Paikkatieto mahdollistaa verkko-operaattoreille ajantasaisen statistiikan keräämisen muuttuvassa radioverkkoympäristössä. Se auttaa myös parantamaan tilannetietoisuutta onnettomuuksien ja pelastusoperaatioiden aikana. Langattomien verkkojen massiivista dataa ei vielä ole …