Готові списки джерел за темами / Ionic aggregation

Добірка наукової літератури з теми "Ionic aggregation"

Автор: Grafiati
Опубліковано: 22 червня 2024

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Зміст

  1. Статті в журналах
  2. Дисертації
  3. Книги
  4. Частини книг
  5. Тези доповідей конференцій
  6. Звіти організацій

Статті в журналах з теми "Ionic aggregation":

1

Williams, Claudine E., Thomas P. Russell, Robert Jerome, and Jacques Horrion. "Ionic aggregation in model ionomers." Macromolecules 19, no. 11 (November 1986): 2877–84. http://dx.doi.org/10.1021/ma00165a036.

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2

Ghadamghahi, Maryam, Davood Ajloo, and Mahmood Moalem. "Kinetic studies on the self-aggregation of a non ionic porphyrin in the presence and absence of ionic liquid by molecular dynamics simulation." Journal of Porphyrins and Phthalocyanines 16, no. 10 (October 2012): 1082–93. http://dx.doi.org/10.1142/s1088424612500915.

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Aggregation kinetics of a porphyrin derivative in the absence and presence of different concentrations, below and above the critical micelle concentration (CMC) of three ionic liquids (ILs); 1-octyl-3-methylimidazolium, 1-dodecyl-3- methyl imidazolium and 1-octadecyl-3-methylimidazolium chloride was studied using molecular dynamics simulation. Effect of IL, with different chain lengths on the aggregation of a porphyrin derivative, 5,10,15,20-tetrakis(2,5-dihydroxyphenyl)porphyrin, was investigated. The low amount of each ionic liquid (below CMC) observed to favors the formation of aggregates; further increasing ionic liquid concentration leads to the destabilization of aggregates. The compared calculated rate constants also support these results. Aggregation of imidazolium ILs proved to take place with longer alkyl chains that favors aggregation.
3

Szilagyi, Istvan, Tamas Szabo, Anthony Desert, Gregor Trefalt, Tamas Oncsik, and Michal Borkovec. "Particle aggregation mechanisms in ionic liquids." Phys. Chem. Chem. Phys. 16, no. 20 (2014): 9515–24. http://dx.doi.org/10.1039/c4cp00804a.

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4

KUBISA, PRZEMYSLAW, and TADEUSZ BIEDRON. "Aggregation of ionic endgroups in polymers." Polimery 41, no. 07/08 (July 1996): 398–405. http://dx.doi.org/10.14314/polimery.1996.398.

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5

Akhter, M. Salim, and Sadiq M. Alawi. "Aggregation of ionic surfactants in formamide." Colloids and Surfaces A: Physicochemical and Engineering Aspects 173, no. 1-3 (November 2000): 95–100. http://dx.doi.org/10.1016/s0927-7757(00)00631-2.

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6

Schulz, Peter S., Karola Schneiders, and Peter Wasserscheid. "Aggregation behaviour of chiral ionic liquids." Tetrahedron: Asymmetry 20, no. 21 (November 2009): 2479–81. http://dx.doi.org/10.1016/j.tetasy.2009.10.010.

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7

Hossain, M. Tofazzal, and Yoichi Aso. "Buffer’s ionic strength on the chaperone-like activity (CLA) of silkworm small heat shock protein: sHSP19.9 and sHSP20.8." Journal of the Bangladesh Agricultural University 12, no. 2 (July 12, 2016): 241–49. http://dx.doi.org/10.3329/jbau.v12i2.28678.

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Small heat-shock proteins (sHSPs), an abundant and ubiquitous family of molecular chaperones, can effectively prevent irreversible aggregation of non-native proteins by forming soluble complex. The CLA of sHSPs is usually determined by the capacity to suppress thermally or chemically induced protein aggregation. Various factors can effectively influence the CLA, and among them the ionic strength of the preparation and working buffer is an important factor. The study deals with the effect of ionic strength of buffer on the CLA of two silkworm sHSPs: namely sHSP19.9 and sHSP20.8 against the thermally-induced aggregation of BLC, a non-native protein. The study clearly revealed that sHSP19.9 required high ionic strength (more NaCl concentration) in reaction buffer to prevent irreversible aggregation of BLC. On the other hand, such high ionic strength condition is not necessary for sHSP20.8 but it influences the activity in some context.J. Bangladesh Agril. Univ. 12(2): 241-249, December 2014
8

Cheng, Shijing, Mingqiang Zhang, Tianyu Wu, Sean T. Hemp, Brian D. Mather, Robert B. Moore, and Timothy E. Long. "Ionic aggregation in random copolymers containing phosphonium ionic liquid monomers." Journal of Polymer Science Part A: Polymer Chemistry 50, no. 1 (October 14, 2011): 166–73. http://dx.doi.org/10.1002/pola.25022.

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9

Borah, Priyanka, та Venkata S. K. Mattaparthi. "Effect of Ionic Strength on the Aggregation Propensity of Aβ1-42 Peptide: An In-silico Study". Current Chemical Biology 14, № 3 (28 грудня 2020): 216–26. http://dx.doi.org/10.2174/2212796814999200818103157.

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Background: Aggregation of misfolded proteins under stress conditions in the cell might lead to several neurodegenerative disorders. Amyloid-beta (Aβ1-42) peptide, the causative agent of Alzheimer’s disease, has the propensity to fold into β-sheets under stress, forming aggregated amyloid plaques. This is influenced by factors such as pH, temperature, metal ions, mutation of residues, and ionic strength of the solution. There are several studies that have highlighted the importance of ionic strength in affecting the folding and aggregation propensity of Aβ1-42 peptide. Objective: To understand the effect of ionic strength of the solution on the aggregation propensity of Aβ1-42 peptide, using computational approaches. Materials and Methods: In this study, Molecular Dynamics (MD) simulations were performed on Aβ1-42 peptide monomer placed in (i) 0 M, (ii) 0.15 M, and (iii) 0.30 M concentration of NaCl solution. To prepare the input files for the MD simulations, we have used the Amberff99SB force field. The conformational dynamics of Aβ1-42 peptide monomer in different ionic strengths of the solutions were illustrated from the analysis of the corresponding MD trajectory using the CPPtraj tool. Results: From the MD trajectory analysis, we observe that with an increase in the ionic strength of the solution, Aβ1-42 peptide monomer shows a lesser tendency to undergo aggregation. From RMSD and SASA analysis, we noticed that Aβ1-42 peptide monomer undergoes a rapid change in conformation with an increase in the ionic strength of the solution. In addition, from the radius of gyration (Rg) analysis, we observed Aβ1-42 peptide monomer to be more compact at moderate ionic strength of the solution. Aβ1-42 peptide was also found to hold its helical secondary structure at moderate and higher ionic strengths of the solution. The diffusion coefficient of Aβ1-42 peptide monomer was also found to vary with the ionic strength of the solution. We observed a relatively higher diffusion coefficient value for Aβ1-42 peptide at moderate ionic strength of the solution. Conclusion: Our findings from this computational study highlight the marked effect of ionic strength of the solution on the conformational dynamics and aggregation propensity of Aβ1-42 peptide monomer.
10

Ogawa, Taku, Nobuhiro Yanai, Saiya Fujiwara, Thuc-Quyen Nguyen, and Nobuo Kimizuka. "Aggregation-free sensitizer dispersion in rigid ionic crystals for efficient solid-state photon upconversion and demonstration of defect effects." Journal of Materials Chemistry C 6, no. 21 (2018): 5609–15. http://dx.doi.org/10.1039/c8tc00977e.

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Статті в журналах Дисертації

Дисертації з теми "Ionic aggregation":

1

Endeward, Burkhard, Marcelino Bernardo, Hans Thomann, and P. Brandt. "Ionic aggregation in metallocene olefin polymerization catalysts." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194837.

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2

Endeward, Burkhard, Marcelino Bernardo, Hans Thomann, and P. Brandt. "Ionic aggregation in metallocene olefin polymerization catalysts: a PFG NMR study." Diffusion fundamentals 3 (2005) 19, S. 1, 2005. https://ul.qucosa.de/id/qucosa%3A14310.

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3

Chakraborty, Gulmi. "Studies on the Aggregation characteristics of selected surfactants and surface active ionic liquids." Thesis, University of North Bengal, 2017. http://ir.nbu.ac.in/handle/123456789/2620.

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4

Ding, Hao. "Influence of solution ionic strength on aggregation of novel water soluble phosphines and two phase catalysis." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-10042006-143900/.

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5

Metzman, Jonathan Seth. "Nanoparticle Encapsulation and Aggregation Control in Anti-reflection Coatings and Organic Photovoltaics." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85580.

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Nanoparticles present a myriad of physical, optical, electrical, and chemical properties that provide valuable functionality to thin-film technologies. In order to successfully exploit these aspects of nanoparticles, appropriate dispersion and stability measures must be implemented. In this dissertation, different types of nanoparticles are coated with polymer and metallic layers to enable their effectiveness in both anti-reflection coatings (ARCs) and organic photovoltaics (OPVs). Ionic self-assembled multilayers (ISAMs) fabrication of poly(allylamine hydrochloride) (PAH) and silica nanoparticles (SiO2 NPs) results in highly-transparent, porous ARCs. However, the ionic bonding and low contact area between the film constituents lack sufficient mechanical and chemical stability necessary for commercial application. Chemical stability was established in the film by the encapsulation of SiO2 NPs by a photo-crosslinkable polyelectrolyte, diazo-resin (DAR) to make modified silica nanoparticles (MSNPs). UV-irradiation induced decomposition of the diazonium group and the development of covalent bonds with polyanions. Crosslinked MSNP/poly(styrene sulfonate) (PSS) ISAMs exhibited excellent anti-reflectivity (transmittance >98%, reflectance <0.2% in the visible range) and chemical stability against dissolution in a ternary solvent. Mechanical stability was also achieved by the incorporation of two additional PAH and poly(acrylic acid) (PAA) layers to create PAH/PAA/PAH/SiO2 NP interlayer ISAM ARCs. Thermal crosslinking of PAH and PAA facilitates the formation of covalent amide bonds between the two polyelectrolytes, as confirmed by FTIR. Since PAH and PAA are both weak polyelectrolytes, adjustment of the solution pH causes significant variations in the polymer chain charge densities. At low PAA pH, the decreased chain charge densities caused large SiO2 NP encapsulation thicknesses in the film with great mechanical stability, but poor anti-reflection (≤97% transmittance). At high PAA pH, the high chain charge densities induced thin encapsulation layers, insufficient mechanical stability, but excellent anti-reflection. At trade-off between the two extremes was founded at a PAA pH of 5.2 with excellent anti-reflection (less than 99% transmittance) and sufficient mechanical stability. The normal force required for scratch initiation was increased by a factor of seven for films made from a pH of 5.2 compared to those made from a pH of 6.0. Organic photovoltaics (OPVs) are an attractive area of solar cell research due to their inexpensive nature, ease of large-scale fabrication, flexibility, and low-weight. The introduction of the bulk heterojunction greatly improved charge transport and OPV performance by the blending of the active layer electron donor and acceptor materials, poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), into an interpenetrating network with high interfacial area between adjacent nanodomains. However, constrained active layer thicknesses restrict the total optical absorption and device performance. The localized surface plasmon resonance (LSPR) of plasmonic nanoparticles, such as anisotropic silver nanoplates (AgNPs), provides large local field enhancements and in coupling with the active layer, substantial optical absorption improvements can be realized. AgNPs were first integrated into the hole-transport layer (PEDOT:PSS) by ISAM deposition. Here, PEDOT:PSS was used as a negatively-charged ISAM layer. Encapsulation of the AgNPs by PAH (ENPs) provided a positive surface charge and allowed for the creation of ENP/PEDOT:PSS ISAMs. Stability against acidic etching by PEDOT:PSS was imparted to the AgNPs by coating the edges with gold (AuAgNPs). The AuAgNP ISAMs substantially improved the optical absorption, but were ineffective at increasing the device performance. The dispersion effects of functionalized polymer coatings on AgNPs were also deeply investigated. Functionalized AgNPs were dispersed in methanol and spin-coated onto the active layer. When the AgNPs possessed hydrophilic properties, such as unfunctionalized or functionalized by poly(ethylene glycol) methyl ether thiol (PEG-SH), they formed large aggregates due to unfavorable interactions with the hydrophobic P3HT:PCBM layer. However, the hydrophobic functionalization of AgNPs with thiol-terminated polystyrene (PS-SH) (PS-AgNPs) resulted in excellent dispersion, optical absorption enhancements, and device performance improvements. At a PS-AgNP concentration of 0.57 nM, the device efficiency was increased by 32% over the reference devices.
Ph. D.
Investigations are presented on the quality of distribution or dispersion of functional inorganic (composed of silicon dioxide or silver) particles that have dimensions of less than 100 nanometers, called nanoparticles. The nanoparticle surfaces were covered with polymer layers, where polymers are organic materials with repeating molecular structures. The study of these nanoparticle distribution effects were first examined in anti-reflection coatings (ARCs). ARCs induce transparency of windows or glasses through a reduction in the reflection of light. Here, the ARCs were fabricated as self-assembled thin-films (films with thicknesses ranging from 1 to 2000 nanometers). The self-assembly process here was carried out by immersing a charged substrate (microscope slide) into a solution with an oppositely-charged material. The attraction of the material to the substrate leads to thin-film growth. The process can continue by sequentially immersing the thin-film into oppositely-charged solutions for a desired number of thin-film layers. This technique is called ionic self-assembled multilayers (ISAMs). ARCs created by ISAM with charged polymers (polyelectrolytes) and silicon dioxide nanoparticles (SiO2 NPs) can lead to highly-transparent films, but unfortunately, they lack the stability and scratch-resistance necessary for commercial applications. In this dissertation, we address the lack of stability in the ISAM ARCs by adding additional polyelectrolyte layers that can develop strong, covalent bonds, while also examining nanoparticle dispersive properties. First, SiO2 NP surfaces were coated in solution with a polyelectrolyte called diazo-resin, which can form covalent bonds by UV-light exposure of the film. After tuning the concentration for the added diazo-resin, the coated SiO2 NPs were used to make ARCs ISAM films. The ARCs had excellent nanoparticle dispersion, high levels of transparency, and chemical stability. Chemically stability entails that the integrity of the film was unaffected by exposure to polar organic solvents or strong polyelectrolytes. In a second method, two additional v polyelectrolyte layers were added into the original polyelectrolyte/SiO2 NP design. Here, heating of the film to 200 oC temperatures induced strong covalent bonding between the polyelectrolytes. Variation of the solution pH dramatically changed the polyelectrolyte thickness, the nanoparticle dispersion, the scratch-resistance, and the anti-reflection. An optimum trade-off was discovered at a pH of 5.2, where the anti-reflection was excellent (amount of transmitted light over 99%), along with a substantially improved scratch-resistance. A change of pH from 6.0 (highest tested pH) to 5.2 (optimal) caused a difference in the scratch-resistance by a factor of seven. In these findings, we introduce stability enhancing properties from films composed purely of polyelectrolytes into nanoparticle-containing ISAM films. We also show that a simple adjustment of solution parameters, such as the pH value, can cause substantial differences in the film properties. Nanoparticle dispersion properties were next investigated in organic photovoltaics (OPVs) OPVs use semiconducting polymers to convert sunlight into usable electricity. They have many advantages over traditional solar cells, including their simple processing, low-cost, flexibility, and lightweight. However, OPVs are limited by their total optical absorption or the amount of light that can potentially be converted to electricity. The addition of plasmonic nanoparticles into an OPV device is a suitable way to increase optical absorption without changing the other device properties. Plasmonic nanoparticles, which are composed of noble metals (such as silver or gold), act as “light antennas” that concentrate incoming light and radiate it around the particle. In this dissertation, we investigate the dispersion and stability effects of polymer or metallic layers on silver nanoplates (AgNPs). The stability of the AgNPs was found to be greatly enhanced by coating the nanoparticle edges with a thin gold layer (AuAgNPs). AuAgNPs could then be introduced into a conductive, acidic layer of the OPVs (PEDOT:PSS) to increase the overall light absorption, which otherwise would be impossible with uncoated AgNPs. Next, the AgNPs were distributed on top of the photoactive layer or the layer that is responsible for absorbing light. Coating the AgNPs with a polystyrene polymer layer (PS-AgNPs) allowed for excellent dispersion on this layer and contrastingly, dispersion of the uncoated AgNPs was poor. An increased amount PS-AgNPs added on top of the photoactive layer progressively increased the optical absorption of the OPV devices. However, trends were quite different for the power conversion efficiency or the ratio of electricity power to sunlight power in the OPV device. The greatest PCE enhancements (27 – 32%) were found at a relatively low coverage level (using a solution concentration of 0.29 to 0.57 nM) of the PS-AgNPs on the photoactive layer.
6

Knowles-Van, Cappellen Victoria Leilani. "The effects of ionic strength and aggregation on crystal growth kinetics : an application of photon correlation spectroscopy." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/20786.

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7

Madenci, Dilek. "Study of the aggregation behaviour of egg yolk lecithin/bile salt mixtures by increasing the ionic strength." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4918.

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This thesis describes a study of the aggregational behaviour of egg yolk lecithin (EYL), a natural lecithin, and bile salt mixtures especially with respect to an increase of the ionic strength of the solvent. Mixtures of two amphiphiles with very different spontaneous curvature as EYL lecithin and bile salt form mixed micelles and vesicles in aqueous solution. Their properties have been well-studied under physiological conditions, i.e. 150 mM electrolyte concentration and pH 7- 8, while other conditions are still hardly explored. Upon increasing ionic strength the formed structures and the transitional pathways (micelles, coexistence of micelles and vesicles, and vesicles) change the generated structures completely from those observed under physiological conditions. We quantitatively determined these structures formed in a broad range of electrolyte concentrations with various scattering techniques, x-ray, light and neutron scattering and calorimetry. With calorimetry, phase diagrams in the EYL and bile salt concentration phase plane were determined at various ionic strength ranging from physiological salt concentration to up to 1000 mM. Additionally a new electrochemical approach using functionalised electrodes, i.e. sensitive and selective to bile salt, and thus to control the bile salt concentration in solution (concentrations below the critical micellar concentration (cmc)) was attempted, since bile salt removal or injection drives the micelle-to-vesicle or the vesicle-to-micelle transition, respectively, of the mixed aggregational system of EYL/bile salt. Although this control was not achieved within the framework of this thesis, promising results show directions for future experiments.
8

Gauthier, Mario. "The effects of matrix glass transition temperature and polarity, and ionic group spacers on ion aggregation in styrene ionomers /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75935.

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Matrix glass transition temperature depression through internal plasticization of a styrene-sodium methacrylate ionomer resulted in enhanced clustering at low plasticization levels (up to ca. 20 mole%). At higher plasticization levels, ion aggregation was strongly disrupted. Matrix polarity effects were studied by nitrating the styrene units of the same ionomer. A sample with a relaxed dielectric constant comparable to acrylate polymers showed no decrease in clustering. Similarly, plasticization with nitrobenzene resulted in typical nonpolar diluent behavior. Polarity was, therefore, not a significant parameter affecting ion aggregation. New styrene copolymers with substituents R = $-$(CH$ sb2$)$ sb{ rm n}$COOMe (n = 1, 5, 10) or R = $-$O(CH$ sb2$)$ sb{ rm n}$COOMe (n = 1, 4, 10) in the para- position were synthesized, to form a systematic investigation of ionic group spacing effects on the dynamic mechanical properties of ionomers. The results were rationalized in terms of bulkiness and rigidity of the units supporting the ionic groups, and polymer backbone immobilization efficiency. Ion solvation effects were also suggested for the ether derivatives.
9

Buell, Alexander Kai. "On the kinetics of protein misfolding and aggregation." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/270324.

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Protein (mis)folding into highly ordered, fibrillar structures, amyloid fibrils, is a hallmark of several, mainly neurodegenerative, disorders. The mechanism of this supra-molecular self-assembly reaction, as well as its relationship to protein folding are not well understood. In particular, the molecular origin of the metastability of the soluble state of proteins with respect to the aggregated states has not been clearly established. In this dissertation, it is demonstrated, that highly accurate kinetic experiments, using a novel biosensing method, can yield fundamental insight into the dynamics of proteins in the region of the free energy landscape corresponding to protein aggregation. First, a section on Method development describes the extension and elaboration of the previously established kinetic assay relying on quartz crystal microbalance measurements for the study of amyloid fibril elongation (Chapter 3). This methodology is then applied in order to study in great detail the origin of the various contributions to the free energy barriers separating the soluble state of a protein from its aggregated state. In particular, the relative importance of residual structure, hydrophobicity (Chapter 4) and electrostatic interactions (Chapter 5) for the total free energy of activation are discussed. In the last part of this thesis (Chapter 6), it is demonstrated that this biosensing method can also be used to study the binding of small molecules to amyloid fibrils, a very useful feature in the framework of the quest for potential inhibitors of amyloid formation. In addition, it is shown that Thioflavin T, to-date the most frequently employed fluorescent label molecule for bulk solution kinetic studies, can in the presence of potential amyloid inhibitor candidates be highly unreliable as a means to quantify the effect of the inhibitor on amyloid formation kinetics. In summary, the work in this thesis contributes to both the fundamental and the applied aspects of the field of protein aggregation.
10

Andreiuk, Bohdan. "Self-assembly of ionic fluorescent dyes inside polymer nanoparticles : engineering bright fluorescence and switching." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF027/document.

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L’encapsulation dans des nanomatériaux de polymères de colorants ioniques à l’aide de contre-ions hydrophobes volumineux apparaît être une méthode très efficace pour générer des nanoparticules (NPs) fluorescentes ultra-brillantes pour la bioimagerie. Nous avons d’abord étendu cette approche par contre-ions aux colorants cyanine opérant dans la gamme du bleu au proche infra-rouge. A partir de NPs chargés en cyanines, une methode de code-barre multicolore pour le traçage cellulaire à long terme a été développé. Ensuite, le rôle des contre-ions hydrophobes volumineux dans l’auto-assemblage des colorants cationiques à l’intérieur des NPs de polymères a été étudié en testant une large collection d’anions. Nous avons montré qu’une forte hydrophobicité du contre-ion augmente l’encapsulation du colorant, régule son clustering et empêche l’agrégation de nanoparticules, alors qu’une grande taille empêche l’auto-inhibition de fluorescence. Enfin, nous avons introduit les contre-ions à base d’aluminates et de barbiturates, qui sur-performent les tetraphénylborates fluorés. Ce travail procure une base solide au concept d’émission et d’encapsulation augmentées par contre-ions pour la préparation de NPs chargés en colorants fluorescents
Encapsulation of ionic dyes with help of bulky hydrophobic counterions into polymer nanomaterials emerged as powerful method for generating ultrabright fluorescent nanoparticles (NPs) for bioimaging. Here, this counterion-based approach is extended to cyanine dyes, operating from blue to near-infrared range. Based on cyanine-loaded NPs, a multicolour cell barcoding method for long-term cell tracking is developed. Second, the role of bulky hydrophobic counterion in self-assembly of cationic dyes inside polymeric NPs is studied by testing a large library of anions. We show that high hydrophobicity of a counterion enhances dye encapsulation, prevents particle aggregation and tunes dye clustering, while large size prevents dyes from self-quenching. Third, counterions based on aluminates and barbiturates are shown to outperform fluorinated tetraphenylborates. This work provides a solid basis for counterion-enhanced encapsulation and emission concept in preparation of dye-loaded fluorescent NPs
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Книги з теми "Ionic aggregation":

1

Jolivet, Jean-Pierre. Metal Oxide Nanostructures Chemistry. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190928117.001.0001.

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This much-anticipated new edition of Jolivet's work builds on the edition published in 2000. It is entirely updated, restructured and increased in content. The book focuses on the formation by techniques of green chemistry of oxide nanoparticles having a technological interest. Jolivet introduces the most recent concepts and modelings such as dynamics of particle growth, ordered aggregation, ionic and electronic interfacial transfers. A general view of the metal hydroxides, oxy-hydroxides and oxides through the periodic table is given, highlighting the influence of the synthesis conditions on crystalline structure, size and morphology of nanoparticles. The formation of aluminum, iron, titanium, manganese and zirconium oxides are specifically studied. These nanomaterials have a special interest in many technological fields such as ceramic powders, catalysis and photocatalysis, colored pigments, polymers, cosmetics and also in some biological or environmental phenomena.

Частини книг з теми "Ionic aggregation":

1

Wang, Jianji, and Huiyong Wang. "Aggregation in Systems of Ionic Liquids." In Structure and Bonding, 39–77. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-38619-0_2.

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2

Zhou, Ting, and Guiying Xu. "Aggregation Behavior of Ionic Liquid-Based Gemini Surfactants and Their Interaction with Biomacromolecules." In Ionic Liquid-Based Surfactant Science, 127–49. Hoboken, NJ: John Wiley & Sons, Inc, 2015. http://dx.doi.org/10.1002/9781118854501.ch6.

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3

Magny, B., I. Iliopoulos, and R. Audebert. "Aggregation of Hydrophobically Modified Polyelectrolytes in Dilute Solution: Ionic Strength Effects." In Macromolecular Complexes in Chemistry and Biology, 51–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78469-9_4.

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4

Espinosa-Marzal, Rosa M., and Zachary A. H. Goodwin. "Colloidal Interactions in Ionic Liquids—The Electrical Double Layer Inferred from Ion Layering and Aggregation." In ACS Symposium Series, 123–48. Washington, DC: American Chemical Society, 2023. http://dx.doi.org/10.1021/bk-2023-1457.ch007.

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Kalugin, Oleg N., Anastasiia V. Riabchunova, Iuliia V. Voroshylova, Vitaly V. Chaban, Bogdan A. Marekha, Volodymyr A. Koverga, and Abdenacer Idrissi. "Transport Properties and Ion Aggregation in Mixtures of Room Temperature Ionic Liquids with Aprotic Dipolar Solvents." In Springer Proceedings in Physics, 67–109. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61109-9_5.

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Driess, Matthias, Robert E. Mulvey, and Matthias Westerhausen. "Cluster Growing Through Ionic Aggregation: Synthesis and Structural Principles of Main Group Metal-Nitrogen, Phosphorus and Arsenic Rich Clusters." In Molecular Clusters of the Main Group Elements, 391–424. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527602445.ch3f.

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7

"Structure Aggregation." In Encyclopedia of Ionic Liquids, 1209. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-33-4221-7_300022.

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Rogers, Michael A. "Self-assembled Fibrillar Networks of Low Molecular Weight Oleogelators." In Edible Nanostructures, 144–78. The Royal Society of Chemistry, 2014. http://dx.doi.org/10.1039/bk9781849738958-00144.

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Self-assembly into nanofibers, although a recently harnessed technology exploited in various industrial applications, occurs naturally in food and biological materials. Proteins, such as gelatin, bovine serum albumin, and β-lactoglobulin, as well as polysaccharides including chitin have most commonly been shown to aggregate into nano-fibers when exposed to appropriate acidic and/or ionic environments. These complex environments lead to protein denaturation and unfolding, followed by aggregation via hydrophobic agglomeration due to the exposed hydrophobic core and secondary hydrogen bonding and disulfide interchanges. The electrostatic, hydrophobic and ionic parameters involved in aggregation are extremely well understood in aqueous environments. However, the underlying principles governing self-assembly into fibrillar networks cannot be extrapolated or applied to hydrophobic environments. In hydrophobic environments, such as vegetable oils, low solubility of proteins and most polysaccharides is an impediment to fibril formation. The insolubility of biological macromolecules has turned the attention of researchers to small amphiphilic molecules capable of aggregating to length scales that are in orders of magnitude greater than their molecular size/volume. These molecules are capable of immobilizing oil via surface tension and capillary forces within a continuous three-dimensional gel network.
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Padinhattath, Sachind Prabha, Baiju Chenthamara, Jitendra Sangwai, and Ramesh L. Gardas. "Ionic Liquids in Advanced Oil Dispersion." In Ionic Liquids for Environmental Issues, 272–92. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781839169625-00272.

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The poor biodegradability and increased toxicity of conventional chemical dispersants have necessitated the use of environmentally benign dispersants. Ionic liquids (ILs), popularly known as green solvents, have emerged as an alternative eco-friendly dispersant in recent years. This chapter summarises and evaluates IL-based formulations for crude oil dispersion. Experimental and computational studies on ILs in the formation of water-in-oil (W/O) or oil-in-water (O/W) emulsions, their aggregation and micellization behaviour, demulsification, toxicological profile, and surface, interface and transport properties are discussed in detail. This chapter aims to understand molecular-level interactions of ILs with oil, explore their potential applications for oil spill remediation and provide relevant information for researchers to develop various eco-friendly IL-based systems.
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Griffin, M. C. A., J. C.Price, and W. G.Griffin. "The heat-induced aggregation of β-lactoglobulin A: photon correlation spectroscopy studies." In Gums and stabilisers for the Food industry 6, 525–29. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780199632848.003.0066.

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Abstract The heat-induced aggregation of P-lacto globulin A &lt;P-LG-A) has been investigated using photon correlation spectroscopy (PCS). A quench technique will be described which makes it possible to ‘freeze’ the aggregation process after a chosen time interval. PCS measurements on the quenched samples of heat-aggregated P-LG-A reveal that a maximum in hydrodynamic radius occurs at a critical temperature which is itself dependent on the ionic environment of the protein. Kinetic studies using the quench technique indicate that two aggregation processes may be brought into play by heat-treatment of P-LG-A solutions and the role of temperature in controlling the predominance of one process over the other results in the observed maximum.

Тези доповідей конференцій з теми "Ionic aggregation":

1

Mattedi, S., M. Martin-Pastor, M. Iglesias, Muhammed Hasan Aslan, Ahmet Yayuz Oral, Mehmet Özer, and Süleyman Hikmet Çaglar. "Structural and Aggregation Study of Protic Ionic Liquids." In INTERNATIONAL CONGRESS ON ADVANCES IN APPLIED PHYSICS AND MATERIALS SCIENCE. AIP, 2011. http://dx.doi.org/10.1063/1.3663104.

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2

sohrabi, Beheshteh, ajin Jalali, and Ali Sharifi. "The ionic liquids counterion effect on their aggregation behavior." In The 17th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2013. http://dx.doi.org/10.3390/ecsoc-17-f005.

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3

Lv, Xiaoxing, Kai Yue, Qingchun Lei, and Xinxin Zhang. "A Molecular Dynamics Simulation of Au Nanoparticles Aggregation in Ionic Solution." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17373.

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Due to unique and tunable optical properties, gold nanoparticles (GNPs) are becoming more widely used in biological and biomedical applications. However, nanoparticles in fluid tend to lose the specific function because of aggregation in the transport process of use. Therefore, it is necessary to investigate the aggregation behavior for having a good understanding of aggregation mechanism and inhibiting GNPs aggregation. A MD simulation in this study was performed to investigate the physical aggregation behavior of GNPs in biological media. By analyzing the aggregation proportion of GNPs in different conditions and the changes in center-to-center distance between GNPs with the time, the effects of the hydrophilic/hydrophobic characteristics of GNPs, velocity of ionic solution, size of GNPs, initial distance between two GNPs, and surface charge were discussed. The simulation results indicate that the aggregation proportion of GNPs with hydrophilic modification is 62.5%, which is less than 87.5% in the model without surface modification, while the final aggregation proportion of GNPs with hydrophobic modification increased to 100%. When the velocity of the NaCl aqueous solution is 0.1 m/s, the final aggregation proportion of GNPs is 87.5%, which is similar with the model without flow velocity. But the final aggregation proportion increased to 100% when the velocity is 1m/s. Under the same conditions, the GNPs of 1 nm diameter aggregated at 0.16 ns, but the GNPs of 1.5 nm and 2 nm diameters aggregated at 0.6 ns and 0.8 ns, respectively. For the GNPs of 1 nm diameter, the GNPs can only get close to each other very slowly when the distance between the surfaces of GNPs is within the range of 0.8–1.2 nm, whereas the GNPs will aggregate quickly when the distance is close enough. GNPs can retain stable by modified with appropriate negative charge. But ions in the solution will weaken this effect.
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Vijayaraghavan, Prasant, and Vishnu-Baba Sundaresan. "Investigating the Effect of Thermoelectric Processing on Ionic Aggregation in Thermoplastic Ionomers." In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3953.

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Ionomers are a class of polymers which contain a small fraction of charged groups in the polymer backbone. These ionic groups aggregate (termed ionic aggregates) to form temporary cross-links that break apart over the ionic dissociation temperature and re-aggregate on cooling, influencing the mechanical properties of these polymers. In addition to enhanced mechanical properties, some ionomers also exhibit self-healing behavior. The self-healing behavior is a consequence of weakly bonded ionic aggregates breaking apart and re-aggregating after puncture or a ballistic impact. The structure and properties of ionomers have been studied over the last several decades; however, there is a lack of understanding of the influence of an electrostatic field on ionic aggregate morphology. Characterizing the effect of temperature and electric field on the formation and structure of these ionic aggregates will lead to preparation of ionomers with enhanced structural properties. This work focuses on Surlyn 8940 which a poly-ethylene methacryclic acid co-polymer in which a fraction of the carboxylic acid is terminated by sodium. In this work, Surlyn is thermoelectrically processed over its ionic dissociation temperature in the presence of a strong electrostatic field. Thermal studies are performed on the ionomer to study the effect of the thermoelectric processing. It is shown that the application of a thermoelectric field leads to increase in the ionic aggregate order in these materials and reduction in crystal size distribution. Thermal Analysis is performed using a Differential Scanning Calorimeter and the resulting thermogram analysis shows that thermoelectric processing increases the peak temperature and onset temperature of melting by 4 C and 20 C respectively. The peak width at half maximum of the melting endotherm is reduced by 10 C due to thermoelectric processing. This serves as a measure of the increased crystallinity. A parametric study on the effect of field duration and field strength is also performed.
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Kumar, Harsh, Jasmeet Kaur, and Pamita Awasthi. "An analysis of the aggregation behaviour of an ionic liquid into water+ carbohydrate solutions – A review." In DIDACTIC TRANSFER OF PHYSICS KNOWLEDGE THROUGH DISTANCE EDUCATION: DIDFYZ 2021. AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0081213.

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6

Turton, David A., Johannes Hunger, Alexander Stoppa, Glenn Hefter, Andreas Thoman, Markus Walther, Richard Buchner, and Klaas Wynne. "Terahertz dynamics of ionic liquids from a combined dielectric relaxation, terahertz, and optical Kerr effect study: evidence for mesoscopic aggregation." In OPTO, edited by Laurence P. Sadwick and Creidhe M. M. O'Sullivan. SPIE, 2010. http://dx.doi.org/10.1117/12.840185.

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7

Biggs, Simon, Michael Fairweather, Timothy Hunter, Qanitalillahi Omokanye, and Jeffrey Peakall. "Engineering Properties of Nuclear Waste Slurries." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16378.

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The type of particulate systems encountered in legacy nuclear waste slurries is highly complicated, with the aggregation and flow behaviour being at times very variable. However, deconstructing the complex overall slurry activity to singular particle-particle interactions can lead to a greater understanding of the mechanisms involved with particle aggregation, and so to predictions of their settling and flow in nuclear systems. Of particular importance to legacy waste is the role of salts in controlling the attraction of particles (and so in dictating the rheological properties of the system) as sludge may contain a variety of specific ions and generally have high ionic conductivity [1]. In this paper, particle-particle interactions are characterised using a number of complimentary methods, and their influence on resulting flow and bed compression is measured. The methods used to characterise the particle-particle interactions under various salt and pH conditions were electroacoustic analysis (zeta potential) and atomic force microscopy (AFM). Following on from the analysis of particle-particle properties, bulk sediment behaviour was investigated using shear and compressive yield stress measurements, vital parameters in dictating flow and dewatering performance, respectively. Together, these techniques enable the characterisation of a range of particulate systems that may be encountered in legacy wastes, and results point to a number of important factors that can help explain the observed variability in industrial slurry behaviour.
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Selak, M. A., M. Chignard, and J. B. Smith. "CHARACTERIZATION OF A NEUTROPHIL CPYMOTRYPSIN-LIKE ENZYME THAT ACTIVATES PLATELETS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643157.

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Communication between neutrophils and platelets was previously investigated by measuring platelet aggregation, serotonin release and changes in cytosolic free calcium subsequent to specific stimulation of neutrophils by fMet-Leu-Phe (FMLP) in a suspension of both cell types. The addition of the chemotactic peptide was shown to elicit secondary platelet activation as a consequence of primary stimulation of neutrophils. Cell-free supernatants from FMLP-stimulated neutrophils were capable of inducing platelet activation thus demonstrating that a factor released bv neutrophils was responsible for the observed platelet responses. After eliminating classical platelet agonists as the acitive agent, it was shown that an enzyme termed neutroohilin induced platelet calcium mobilization, secretion and aggregation. The current studies were conducted to characterize the mediator released bv neutrophils. Neutrophilin bound bo cation exchange resins but failed to bind to anion exchangers. The biological activity associated with neutroohilin was unaffected by leupeptin, only very weakly diminished by N-bosyl-Lvs-chloromethvl ketone and was strongly inhibited by N-tosvl-Phe-chloromethvl ketone, aloha-l-antitrvpsin, soybean trypsin inhibitor and Z-Glv-Leu-Phe-chloromethvl ketone. Neutroohilin was released from stimulated neutrophils only after cytochalasin B treatment, as was beta-glucuronidase, suggesting that both enzymes are located in azurophilic granules. Neutroohilin-induced platelet activation was inhibited bv antiserum to human catheosin G in a dose-deoendent manner but was unaffected by antiserum to human elastase or alpha-fetoprotein. The inhibitor sensitivity, immunological cross-reactivity, ionic properties and probable subcellular localization indicate that neutrophilin is a cationic chymotrvosin-like enzyme related, if not identical to, catheosin G. Neutroohilin-induced platelet activation could explain different pathological events in which platelets and neutroohils are known to be involved.
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Romanin, Vincent D., and Sonia Fereres. "A Meta-Analysis of the Specific Heat Enhancement of Nanofluids." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37951.

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The ability to engineer enhanced thermal properties by adding small amounts of nanoparticles to liquids is especially attractive in the case of heat transfer fluids, which find applications in many types of power and heat generation. The specific heat capacity of nanofluids is an important parameter in the design of these systems, especially in the case of thermal energy storage. As with many nanofluid properties, the nature and extent of the modification of the specific heat capacity with the addition of nanoparticles is not well established, and many publications report conflicting experimental data. In contrast to thermal conductivity enhancements, it is yet unclear whether the specific heat capacity of a nanoparticle suspension can increase with respect to the base fluid value. In order to help determine the magnitude, nature, and theory of specific heat capacity modification with the addition of nanoparticles, published experimental heat capacity data for nanofluids was compiled and analyzed to investigate any trends or biases in the data. The objective of this meta-analysis is twofold: 1) to clarify in what cases an enhancement of specific heat capacity can be expected, and 2) to understand the mechanisms responsible for this behavior. It is hypothesized that reported anomalous specific heat enhancements are related to the ionic nature of the base fluid and, therefore, to particle-fluid interactions. Theories of nanofluid heat capacity are discussed in the context of the compiled data. Other factors are also discussed, including the effect of the heat capacity measurement technique, nanofluid synthesis methods, aggregation and dispersion and the characterization thereof, and the effect of base fluid, nanoparticle size, shape, and material. Finally, recommendations are made for improving the reliability and consistency in synthesizing and characterizing nanofluids and their thermal properties.
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Lamsal, Buddhi, and Bibek Byanju. "Processing opportunities and challenges for plant-based proteins." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/cjmp7212.

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With demand for nutritious and functional protein-rich ingredients rising, there are opportunities to acquire protein from new/ emerging sources, as well as from coproducts of agro-food industry. Some of these sources include plants/ seeds and oilseeds, microalgae, fungi, cell/ microbial, and insect protein; however, each of these may have their own unique challenges in terms of extraction, nutritional profile, bioactivity, techno-functional properties, safety, allergenicity as well as in food and feed applications. Some of the challenges for plant/seed proteins are that they have relatively lower extraction yields and relatively inferior functional/ nutritional aspects, including off-flavor and digestibility. Protein quality in defatted meals is also impacted by harsh oil removal process, which is further exacerbated by the downstream protein extraction and isolation conditions (pH, ionic strength, temperature etc.) resulting in protein denaturation, aggregation, and potential loss of functionality. Also, plant proteins have other issues such as off-flavors, astringency/ taste, allergenicity, and antinutritional factors that reduce mineral bioavailability and protein absorption. Various food processing techniques can be used to reduce/ remove these aspects of protein ingredients; fermentation, germination, heating, enzymatic, or acidic treatment, membrane separation etc. have been employed to improve protein purity and quality. The choice of processing technology, even for oil removal from oilseed, impacts protein extraction and quality. For example, protein recovered from meal/ fibers of aqueous oil extraction were of better quality than from desolventized meals. Emerging physical and biochemical processes, such as high-power sonication, extrusion, high-pressure processing, microwave, pulsed electric field, enzymatic pretreatment (pectinase, proteinase, carbohydrase), and fermentation are reported to increase protein extraction efficiency, removing/ reducing allergenicity, and modify functional characteristics. This presentation will discuss such processing challenges and opportunities for plant-based proteins for extraction and downstream isolation, as well as their impact on important functional characteristics.

Звіти організацій з теми "Ionic aggregation":

1

Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova, and Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604286.bard.

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The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.

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