24 research outputs found
Correction: Substituent interference on supramolecular assembly in urea gelators: synthesis, structure prediction and NMR
Correction for ‘Substituent interference on supramolecular assembly in urea gelators: synthesis, structure prediction and NMR’ by Francesca Piana et al., Soft Matter, 2016, 12, 4034–4043
Substituent interference on supramolecular assembly in urea gelators: synthesis, structure prediction and NMR
Eighteen N-aryl-N?-alkyl urea gelators were synthesised in order to understand the effect of head substituents on gelation performance. Minimum gelation concentration values obtained from gel formation studies were used to rank the compounds and revealed the remarkable performance of 4-methoxyphenyl urea gelator 15 in comparison to 4-nitrophenyl analogue 14, which could not be simply ascribed to substituent effects on the hydrogen bonding capabilities of the urea protons. Crystal structure prediction calculations indicated alternative low energy hydrogen bonding arrangements between the nitro group and urea protons in gelator 14, which were supported experimentally by NMR spectroscopy. As a consequence, it was possible to relate the observed differences to interference of the head substituents with the urea tape motif, disrupting the order of supramolecular packing. The combination of unbiased structure prediction calculations with NMR is proposed as a powerful approach to investigate the supramolecular arrangement in gel fibres and help understand the relationships between molecular structure and gel formation
Static secondary ion mass spectrometry investigation of corrosion inhibitor Irgamet ® 39 on copper surfaces treated in power transformer insulating oil
Substituent interference on supramolecular assembly in urea gelators: synthesis, structure prediction and NMR
Eighteen N-aryl-N'-alkyl urea gelators were synthesised in order to understand the effect of head substituents on gelation performance. Minimum gelation concentration values obtained from gel formation studies were used to rank the compounds and revealed the remarkable performance of 4-methoxyphenyl urea gelator 15 in comparison to 4-nitrophenyl analogue 14, which could not be simply ascribed to substituent effects on the hydrogen bonding capabilities of the urea protons. Crystal structure prediction calculations indicated alternative low energy hydrogen bonding arrangements between the nitro group and urea protons in gelator 14, which were supported experimentally by NMR spectroscopy. As a consequence, it was possible to relate the observed differences to interference of the head substituents with the urea tape motif, disrupting the order of supramolecular packing. The combination of unbiased structure prediction calculations with NMR is proposed as a powerful approach to investigate the supramolecular arrangement in gel fibres and help understand the relationships between molecular structure and gel formation
A surface analytical chemistry approach to copper corrosion and its inhibition with benzotriazole derivatives in oil-filled power transformers
In this thesis is discussed the possible application of surface analytical chemistry techniques to the study of copper corrosion and its inhibition in insulating oils. In particular, the techniques investigated were X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SSIMS). XPS was used, in combination with energy-dispersive spectroscopy (EDX), to study the formation and migration of the corrosion by-product copper sulfide on both copper conductors and paper insulation, as a consequence of their exposure to corrosive insulating oils. Its surface atomic sensitivity allowed the study of the influence of variables such as concentration of corrosive species, oxygen, time and copper-paper proximity on the corrosion process. This ultimately led to the formulation of a new bifurcated mechanism to explain how copper sulfide might contaminate the insulating system of power transformers filled with corrosive oils. Additionally, XPS could also be used to study the inhibitor layer formed by the benzotriazole derivative Irgamet®39 on copper immersed in oil. The corrosion inhibitor was detected as a local enrichment of nitrogen on copper substrates, solely induced by the presence of its surface-active tolyltriazole moiety. Remarkably, it was possible to identify a correlation between the amount of corrosion inhibitor present in the oil and that effectively protecting copper, while estimating the thickness of the protection layer and the optimal amount of corrosion inhibitor to be used in real-life applications. SSIMS was used to increase the understanding of the copper inhibition process in oil by means of tolyltriazole. Thanks to its surface molecular sensitivity it was possible to obtain a new insight on the surface chemistry of the inhibitor, while investigating the effect of local temperature changes on the metal coverage and its stability under vacuum with the help of ion imaging. Moreover, it was also possible to estimate the energy of desorption of the tolyltriazole molecules from the copper surface. Finally, SSIMS ion imaging was shown to be a potentially valuable asset in forensic investigations, being able to track the distribution of corrosion inhibitor and by-products in decommissioned or failed power transformers
Praxis Beneficiorum D. Petri Rebuffi ... : cui apposuimus bullam coenae Domini, bullam ieiuniorum ac supplicationum ... P. Pauli III multis in locis restituta omnia & hac editione aliquot additamentis ... ex postrema auctoris recognitione locupletata ; accesserunt etiam nunc recens additiones ad regulas Cancellariae cum interpretationibus D. Petri Rebuffi, cura D. Audomari Rebuffi ... excultae ; his etiam adiecta est practica Cancellariae ... D. Hieronymi Pauli Barchin ...
Al colofó: 1594Marca de l'impr. a port.Sign.: a-c8, d6, A-Z8, Aa-Ss8, Tt4Text a dos col., post. impr. i reclamsFrisos i capll.IndexRef.: CCPB000024711-1, CCBE S. XVI, R, 41
Acquisition of new members/support for Amnesty International
In this Bachelor’s thesis, a group of students were subjected to a presentation during the autumn of 2010 then a survey in order to prove whether Amnesty International could acquire new members/support between the ages of 18 to 28 through in-school awareness creation. The idea is that a single member of the organisation could acquire a bunch of new members from within the university through a simple awareness creation campaign. The conducted survey proved that a large number of students had no idea what Amnesty International was. The thesis highlights which product Amnesty could sell to this age group then further underlines reasons why the selected product works best with this target group.
The theory part of this thesis covers acquisition of new members who are referred to as new customers in addition to background information about Amnesty International. Also, the Universal Declaration of Human Rights is mentioned in this thesis for Amnesty International’s overall purpose is upholding these rights. As this study is conducted in Finland, the dominant culture of the age range is Finnish; because of this, Finnish cultural and communication are highlighted in the theory part which serve as reasons to why the selected product was chosen for this particular group and also the best way to approach individuals from this culture. Finally, video interviews were conducted to support findings for this thesis
Static secondary ion mass spectrometry investigation of corrosion inhibitor Irgamet®39 on copper surfaces treated in power transformer insulating oil
Static secondary ion mass spectrometry was used to study the corrosion inhibitor Irgamet®39 on the surface of copper treated in insulating oils and the effect of temperature changes, by means of temperature programmed desorption experiments under vacuum, on metal coverage. Four commercial oils, both corrosive and non-corrosive, showed no significant influence on the stability of the tolyltriazole layer and the energy of its main desorption event from copper was calculated around 100 kJ mol?1. Finally, an example of ion imaging as diagnostic tool to track the distribution of corrosion inhibitor and by-products in decommissioned or failed power transformers is described