Search results for "composition"
showing 10 items of 2675 documents
No carrier-added nucleophilic aromatic radiofluorination using solid phase supported arenediazonium sulfonates and 1-(aryldiazenyl)piperazines
2012
Abstract This Letter concerns the investigation of a solid phase based method for no carrier-added nucleophilic [ 18 F]fluorination of aromatic compounds via de-diazofluorination. Initial screening of reaction conditions was conducted using soluble analogues, that is, substituted benzenediazonium tosylates and 1-(phenyldiazenyl)piperazines in solution. This was followed by translation of the principle conditions to solid phase bound analogues. A variety of substituted aryldiazonium cations were immobilised using a sulfonate functionalised ion exchange resin and labelled with [ 18 F]fluoride ion by Balz–Schiemann like thermal decomposition in the presence of no carrier-added [ 18 F]fluoride …
Effect of heating of organo-montmorillonites under different atmospheres
2009
Abstract We studied the influence of heating on the behaviour of two organo-montmorillonites paying particular attention to the possible degradation effects of the organic modifier under different atmospheres. Hoffmann elimination and anucleophilic substitution on the nitrogen led to rapid degradation of the modifier. As confirmed by deconvoluted FTIR spectra, the presence of oxygen accelerated the degradation rate. The degradation products of the modifier (α-olefins transforming into various carboxyl compounds if oxygen is present) initially increased the basal spacing, followed by a collapse of the particle layers when the decomposition products migrated toward the surface and eventually …
Análise de divulgação de risco no Relatório Anual de Governança corporativa utilizando fuzzy-set qualitative comparative analysis
2016
ABSTRACT This paper explores the necessary and sufficient conditions of good Corporate Governance practices for high risk disclosure by firms in their Corporate Governance Annual Report. Additionally, we explore whether those recipes have changed during the financial crisis. With a sample of 271 Spanish listed companies, we applied fuzzy-set qualitative comparative analysis to a database of financial and non-financial data. We report that Board of Directors independence, size, level of activity and gender diversity, CEO duality, Audit Committee independence, being audited by the Big Four auditing firms and the presence of institutional investors are associated with high risk disclosure. The…
Investigating the impacts of team type and design on virtual team processes
2017
While much is known about virtual team processes and outcomes, the literature relies on a variety of team configurations and types (including student versus organizational samples, short-term versus long-term teams, functional versus project-based teams, and teams with various task types) yet has not systematically examined how these differences impact team processes. This is important because much of the virtual teams research has been based on student samples, which are easier to access and control, with the implicit assumption that the findings from student samples will generalize to organizational virtual teams. This manuscript reviews the last 15 years of research on virtual teams and …
Student commitment to social responsibility: Systematic literature review, conceptual model, and instrument
2021
Purpose: This study aims to carry out a systematic literature review on empirical manifestations of the student commitment to social responsibility in order to propose a conceptual model that systematizes the underlying patterns in these manifestations and an instrument that makes it measurable. Design/methodology/approach: Four macro-processes were deployed: identify (locate the relevant literary space; the initial sample comprised 52 studies which later resulted in a sample of 24 studies), describe (narrative synthesis of the studies), deepen ( grouping patterns, validation, and characterization of the relevant literary space), and disseminate (preparation/refinement of the report). Findi…
Work engagement-team performance relationship : shared job crafting as a moderator
2016
The aims of this study were twofold: first, to investigate whether both individual and team work engagement are associated with team members' perceived team performance, and, second, to explore whether shared job crafting within teams moderates the relationship between work engagement and team members' perceived team performance. Data were collected from 1,074 Finnish educational sector employees working in 102 teams. Multilevel analysis revealed that both individual and team work engagement were associated with high levels of perceived team performance. The association between work engagement (both individual and team) and perceived team performance, however, varied across teams. The varia…
New light on an old debate: Does the RCN-PtCl2 bond include any back-donation? RCN←PtCl2 backbonding: Vs. the IR ν CN blue-shift dichotomy in organon…
2019
For a series of organonitrile [RCN (R = Me, CF3, Ph, CH3Ph, CF3Ph)] ligands, the nature of the N-Pt bond in the related cis-/trans-(RCN)2PtCl2 complexes has been computationally investigated by Density Functional Theory. A fragment based bond analysis has been performed in the canonical Kohn-Sham molecular orbitals framework, and it has been ultimately assessed that this bond is characterized both by N→Pt σ and by N←Pt π contributions. Voronoi Deformation Density charges further confirms the occurrence of N←Pt π interactions. Moreover, the Energy Decomposition Analysis-Natural Orbital for Chemical Valence (EDA-NOCV) method shows that the strength of the N←Pt π interaction is not negligible …
Chemical composition of essential oils from Pantelleria Island autochthonous and naturalized spices and evaluation of their individual and combined a…
2019
In this study, the antimicrobial activity of the essential oils (EOs) from Origanum majorana L. and Rosmarinus officinalis L. growing in Pantelleria (Sicily, Italy) were tested alone and in combination against some prokaryotic and eukaryotic food-borne pathogens. The chemical composition of the EOs as well as the minimum inhibitory concentrations (MIC) against the most sensitive strains were also determined. Both EOs showed interesting antimicrobial effects against all bacteria and yeasts tested. MIC was in the range 1.25–2.50 µl/ml. Interestingly, O. majorana was particularly rich in thymol acetate, while carvacrol was present at very low percentages. Also R. officinalis EOs composition wa…
An assessment of factors controlling N
2016
Management of plant residues plays an important role in maintaining soil quality and nutrient availability for plants and microbes. However, there is considerable uncertainty regarding the factors controlling residue decomposition and their effects on greenhouse gas (GHG) emissions from the soil. This uncertainty is created both by the complexity of the processes involved and limitations in the methodologies commonly used to quantify GHG emissions. We therefore investigated the addition of two soil residues (durum wheat and faba bean) with similar C/N ratios but contrasting fibres, lignin and cellulose contents on nutrient dynamics and GHG emission from two contrasting soils: a low-soil org…
A comparison of the effects of ?-ketotriazole, MCPA and carbaryl on the plasma membrane Mg2+-ATPase activity and lipid composition of rice shoots (Or…
1993
The effect of γ-ketotriazole, MCPA and carbaryl on the lipid composition and ATPase activity associated with plasma membrane fractions from rice (Oryza sativa cv Bahia) shoots was investigated. With γ-ketotriazole and MCPA treatments the relative amount of δ5-avenasterol (%) was reduced in the plasma membrane, whereas with γ-ketotriazole a reduction was also found in the sitosterol content, expressed as a percentage of the total free sterol composition. The fatty acyl chain length of phosphatidylcholine fractions from MCPA-treated plants was also reduced. The plasma membrane Mg2+-ATPase activity was only stimulated in MCPA-treated plants. No changes were observed in lipid composition or ATP…