Browsing by Subject "Dissolution"

Now showing 1 - 9 of 9
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    The effect of cucurbit[n]uril on the solubility, morphology, and the photophysical properties of nonionic conjugated polymers in an aqueous medium
    (2010) Tuncel, D.; Artar, M.; Hanay, S. B.
    The effects of cucurbit[n]uril on the dissolution and the photophysical properties of nonionic conjugated polymers in water are described. For this purpose, a fluorine-based polymer, namely, poly[9,9-bis{6(N,N-dimethylamino) hexyl}fluorene-co-2,5-thienylene (PFT) was synthesized and characterized by spectroscopic techniques including 1D and 2D NMR, UV-vis, fluorescent spectroscopy, and matrix-assisted laser desorption mass spectrometry (MALDI-MS). For the first time, it was demonstrated that a nonionic conjugated polymer can be made soluble in water through an inclusion complex formation with CB8. The structure of the complex was elucidated by NMR experiments including 1H and selective 1D-NOESY. This complex emits green and is highly fluorescent with fluorescent quantum yield of 35%. In contrast, CB6 or water-soluble CB7 although they are chemically identical to CB8 do not have any effect on the dissolution and photophysical properties of PFT. By preparing a protonated version of PFT, the optical properties of PFT in methanol, protonated PFT and PFT@CB8 in water have been studied and compared. It was also observed that the morphology of the polymer PFT was affected by the presence of CB8. Thus CB8-assisted self-assembly of polymer chains leads to vesicles formation; these structures were characterized by DLS, AFM, SEM, and TEM fluorescent optical microscopy.
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    Electrospinning of cyclodextrin/linalool-inclusion complex nanofibers: fast-dissolving nanofibrous web with prolonged release and antibacterial activity
    (Elsevier, 2017-09) Aytac Z.; Yildiz, Z. I.; Kayaci-Senirmak, F.; Tekinay, T.; Uyar, Tamer
    The volatility and limited water solubility of linalool is a critical issue to be solved. Here, we demonstrated the electrospinning of polymer-free nanofibrous webs of cyclodextrin/linalool-inclusion complex (CD/linalool-IC-NFs). Three types of modified cyclodextrin (HPβCD, MβCD, and HPγCD) were used to electrospin CD/linalool-IC-NFs. Free-standing CD/linalool-IC-NFs facilitate maximum loading of linalool up to 12% (w/w). A significant amount of linalool (45–89%) was preserved in CD/linalool-IC-NFs, due to enhancement in the thermal stability of linalool by cyclodextrin inclusion complexation. Remarkably, CD/linalool-IC-NFs have shown fast-dissolving characteristics in which these nanofibrous webs dissolved in water within two seconds. Furthermore, linalool release from CD/linalool-IC-NFs inhibited growth of model Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria to a great extent. Briefly, characteristics of liquid linalool have been preserved in a solid nanofiber form and designed CD/linalool-IC-NFs confer high loading capacity, enhanced shelf life and strong antibacterial activity of linalool.
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    Fast-dissolving, prolonged release, and antibacterial cyclodextrin/limonene-inclusion complex nanofibrous webs via polymer-free electrospinning
    (American Chemical Society, 2016) Aytac Z.; Yildiz, Z. I.; Kayaci-Senirmak, F.; S. Keskin, N. O.; Kusku, S. I.; Durgun, Engin; Tekinay, T.; Uyar, Tamer
    We have proposed a new strategy for preparing free-standing nanofibrous webs from an inclusion complex (IC) of a well-known flavor/fragrance compound (limonene) with three modified cyclodextrins (HPβCD, MβCD, and HPγCD) via electrospinning (CD/limonene-IC-NFs) without using a polymeric matrix. The experimental and computational modeling studies proved that the stoichiometry of the complexes was 1:1 for CD/limonene systems. MβCD/limonene-IC-NF released much more limonene at 37, 50, and 75 °C than HPβCD/limonene-IC-NF and HPγCD/limonene-IC-NF because of the greater amount of preserved limonene. Moreover, MβCD/limonene-IC-NF has released only 25% (w/w) of its limonene, whereas HPβCD/limonene-IC-NF and HPγCD/limonene-IC-NF released 51 and 88% (w/w) of their limonene in 100 days, respectively. CD/limonene-IC-NFs exhibited high antibacterial activity against E. coli and S. aureus. The water solubility of limonene increased significantly and CD/limonene-IC-NFs were dissolved in water in a few seconds. In brief, CD/limonene-IC-NFs with fast-dissolving character enhanced the thermal stability and prolonged the shelf life along with antibacterial properties could be quite applicable in food and oral care applications.
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    Insight on tricalcium silicate hydration and dissolution mechanism from molecular simulations
    (American Chemical Society, 2015) Manzano, H.; Durgun, Engin; Arbeloa, I. L.; Grossman, J. C.
    Hydration of mineral surfaces, a critical process for many technological applications, encompasses multiple coupled chemical reactions and topological changes, challenging both experimental characterization and computational modeling. In this work, we used reactive force field simulations to understand the surface properties, hydration, and dissolution of a model mineral, tricalcium silicate. We show that the computed static quantities, i.e., surface energies and water adsorption energies, do not provide useful insight into predict mineral hydration because they do not account for major structural changes at the interface when dynamic effects are included. Upon hydration, hydrogen atoms from dissociated water molecules penetrate into the crystal, forming a disordered calcium silicate hydrate layer that is similar for most of the surfaces despite wide-ranging static properties. Furthermore, the dynamic picture of hydration reveals the hidden role of surface topology, which can lead to unexpected water tessellation that stabilizes the surface against dissolution.
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    Phase separation in liquid crystalline mesophases of [Co(H 2O)6]X2: P65 Systems (X = NO3-, Cl-, or ClO4-)
    (2007) Albayrak, C.; Gülten, G.; Dag, Ö.
    Transition-metal aqua complex salts [M(H2O)6]X 2 (where M is Mn(II), Co(II), Ni(II), Zn(II), or Cd(II) and X is NO3-, Cl-, or ClO4-) can be dissolved in triblock poly(ethylene oxide) - poly(propylene oxide) - poly(ethylene oxide) copolymers (Pluronics, such as P65) to form homogeneous liquid crystalline (LC) mesophases. However, the [Co-(H2O) 6]X2:P65 LC mesophases slowly undergo phase separation into a disordered ion-free phase and an ordered ion-rich LC mesophase. The phase separation also takes place in the two-salt systems [Co(H2O) 6](NO3):[Co(H2O)6]-(ClO 4)2:P65 in which the ion-free disordered domains separate out from the initially ordered homogeneous mesophase. The phase separation results in a physical mixture of a hexagonal nitrate-rich and cubic perchlorate-rich LC and disordered ion-free domains in the mixed salt systems. The driving force in the phase separation in the [Co(H2O) 6]-X2:P65 system is Co(II)-catalyzed aerobic oxidation of P65 into ester and/or other oxidation products. The separation of ions in the [Co(H2O)6](NO3)2:[Co(H 2O)6](ClO4)2:P65 system is related to the mesostructures of the two-salt systems that are different, hexagonal in the [Co(H2O)6](NO3)2:P65 system and cubic in the [Co(H2O)6](ClO4)2:P65 system. There is no visible phase separation in the other transition-metal salt:P65 systems. The phase separation in the [Co-(H2O) 6]X2:P65 systems can also be eliminated by keeping the mesophase under a N2 atmosphere. © 2007 American Chemical Society.
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    A porosity difference based selective dissolution strategy to prepare shape-tailored hollow mesoporous silica nanoparticles
    (Royal Society of Chemistry, 2015) Yildirim, A.; Bayındır, Mehmet
    This article reports a general method to prepare hollow mesoporous silica nanoparticles with tailored morphology. The method is based on selective dissolution of porous cores of solid silica shell/porous silica core nanoparticles under mild conditions without the need for corrosive or toxic etchants. First, core-shell nanospheres or nanorods are prepared in a one-pot reaction. Then, mesoporous cores of the nanoparticles are selectively dissolved by incubating them in phosphate buffered saline (PBS) at 65 °C for one day. Surprisingly, shells of the resulting hollow particles contain both small and large mesopores which makes the particles very suitable for adsorption and desorption of a wide range of molecules. In addition, we proposed a mechanism for selective dissolution of porous cores of the core-shell nanoparticles.
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    The prosopography of English monastic orders at the dissolution: evidence from the national archives assessed
    (Liverpool University Press, 2019) Thornton, David E.
    This paper evaluates a number of series of document at The National Archives as evidence for the prosopography of monastic orders in England and Wales during the second half of the 1530s. In particular, the testimony of the acknowledgments of the Oath of Supremacy in 1534 (TNA, E 25), the certificates of the suppression commissioners in 1536, the deeds of surrender from 1538–40 (TNA, E 322), and the various types of document which outline monastic pensions are assessed in so far as they record the identity and numbers of monks, regular canons and nuns at the time of the Dissolution. The paper demonstrates that, despite the importance of these various primary sources, none when taken alone completely and accurately describe the religious personnel of individual monasteries, and concludes with a call for a fresh examination and publication of the relevant documents.
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    Quantitative phase evolution during mechano-synthesis of Ti-Ni-Cu shape memory alloys
    (Elsevier, 2012-05-29) Amini, R.; Alijani, F.; Ghaffari, M.; Alizadeh, M.; Okyay, Ali Kemal
    Ti-41Ni-9Cu shape memory alloy was synthesized by mechanical alloying of pure elemental Ti, Ni, and Cu powders using high-energy ball milling. The qualitative and quantitative phase analyses of the as-milled powders were done by X-ray diffraction (XRD) using Rietveld refinement and the alloys microstructure was studied by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Concerning the results, by milling evolution, the dissolution of the primary materials occurred at different rates and a considerable amount of the amorphous phase as well as B19′-martensite and B2-austenite was created. The formation of Ni solid solution was also evidenced prior to its dissolution. It was found that at sufficient milling time, the mechano-crystallization of the amorphous phase occurred and at the end of milling, the B19′-martensite is the dominant phase of the structure.
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    The wars of Yugoslav dissolution and Britain's role in the making of international policy
    (1999) Osmancavusoglu, Emel G.
    This study is a chronological examination of British politics and diplomacy concerning the Former Yugoslavia from the explosion of war in 1991 right up to the signing of the Dayton Peace Agreement in December 1995. As such, it serves as a case study of British diplomacy during that period. All in all, British policy towards the Yugoslav dissolution wars was evaluated as unsuccessful both in terms of achieving a stable peace in the region and containing the conflict. The major aim of this study is to analyse the basic considerations and main motives behind the British policy in dealing with the wars of Yugoslav dissolution. The study attempts to look at the question whether or not any particular responsibility for the inadequate international response to the Yugoslav crisis can be attributed to Britain. The study argues that Britain’s Conservative government, rather than attempting to lead international community to take more robust stance against Serbian genocidal war in Bosnia and Hercegovina, used its diplomatic skills to subdue discussion of using force whenever the issue arose and severely hampered a collective response to the crisis. As a result, it is argued that Major government’s unwillingness to go beyond humanitarian intervention, despite pressure from the US, from the media and public and from two main opposition parties, reinforced its image of weakness and incompetence and thus did have important political implications both at home and abroad.