scholarly journals Atomic-Scale Investigation on the Evolution of Tio2-Anatase Prepared by a Sonochemical Route and Treated with NaOH

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 685
Author(s):  
Berenice Victoria Dimas ◽  
Isaías Hernández Pérez ◽  
Vicente Garibay Garibay Febles ◽  
Lucía Díaz Barriga Díaz Barriga Arceo ◽  
Raúl Suárez Suárez Parra ◽  
...  

To date, the formation mechanisms of TiO2, as well as its heterostructures, have not been clarified. Moreover, detailed research on the transition from a tetragonal anatase phase to the monoclinic phase of the TiO2(B) phase and their interface structure has been quite limited until now. In the present study, we report on the sonochemical synthesis of TiO2-anatase with a crystallite size of 5.2 ± 1.5 nm under different NaOH concentrations via the hydrothermal method. The use of alkaline solution and the effect of the temperature and reaction time on the formation and structural properties of TiO2-anatase nanopowders were studied. The effects of NaOH concentration on the formation and transformation of titanate structures are subject to thermal effects that stem from the redistribution of energy in the system. These mechanisms could be attributed to three phenomena: (1) the self-assembly of nanofibers and nanosheets, (2) the Ostwald ripening process, and (3) the self-development of hollow TiO2 mesostructures.

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 310
Author(s):  
Hao Kong ◽  
Bin Liu ◽  
Guozheng Yang ◽  
Yun Chen ◽  
Gang Wei

Studying the interactions between biomolecules and material interfaces play a crucial role in the designing and synthesizing of functional bionanomaterials with tailored structure and function. Previously, a lot of studies were performed on the self-assembly of peptides in solution through internal and external stimulations, which mediated the creation of peptide nanostructures from zero-dimension to three-dimension. In this study, we demonstrate the self-assembly behavior of the GNNQQNY peptide on the surface of mica and highly oriented pyrolytic graphite through tailoring the self-assembly conditions. Various factors, such as the type of dissolvent, peptide concentration, pH value, and evaporation period on the formation of peptide nanofibers and nanoribbons with single- and bi-directional arrays are investigated. It is found that the creation of peptide nanoribbons on both mica and HOPG can be achieved effectively through adjusting and optimizing the experimental parameters. Based on the obtained results, the self-assembly and formation mechanisms of peptide nanoribbons on both material interfaces are discussed. It is expected that the findings obtained in this study will inspire the design of motif-specific peptides with high binding affinity towards materials and mediate the green synthesis of peptide-based bionanomaterials with unique function and application potential.


2016 ◽  
Vol 18 (47) ◽  
pp. 32534-32540 ◽  
Author(s):  
Zhan-Wei Li ◽  
You-Liang Zhu ◽  
Zhong-Yuan Lu ◽  
Zhao-Yan Sun

A vast collection of fascinating supracolloidal fullerene-like cages has been achievedviathe self-assembly of soft three-patch particles designed to mimic non-planar sp2hybridized carbon atoms in fullerenes, through the rational design of patch configuration, size, and interaction.


2019 ◽  
Author(s):  
Armando Díaz-Valle ◽  
José Marcos Falcón-González ◽  
Mauricio Carrillo-Tripp

AbstractIn order to rationally design biopolymers that mimic biological functions, first, we need to elucidate the molecular mechanisms followed by nature. For example, the viral capsid is a macromolecular complex formed by self-assembled proteins which, in many cases, are biopolymers with an identical amino acid sequence. Specific protein-protein interactions drive the capsid self-assembly process, leading to several distinct protein interfaces. Following the hot-spot hypothesis, we propose a conservation-based methodology to identify those interface residues that are crucial elements on the self-assembly and thermodynamic stability of the capsid. We validate our predictions by computational free energy calculations using an atomic-scale molecular model of an icosahedral virus. Our results show that a single mutation in any of the hot-spots significantly perturbs the quaternary interaction, decreasing the absolute value of the binding free energy, without altering the tertiary structure. Our methodology can lead to a strategy to rationally modulate the capsid’s thermodynamic properties.


2016 ◽  
Vol 22 (49) ◽  
pp. 17843-17856 ◽  
Author(s):  
Balaram Pradhan ◽  
V. M. Vaisakh ◽  
Geetha G. Nair ◽  
D. S. Shankar Rao ◽  
S. Krishna Prasad ◽  
...  

2020 ◽  
Vol 11 (SPL4) ◽  
pp. 1820-1825
Author(s):  
Al-Khafaji Enas

Fatty amines or primary alkyl-amines like hexylamine, Octylamine, Decylamine, Dodecylamine, Tetradecylamine, Hexadecylamine, and Octadecylamine have been used widely in nanoparticles formation, preparation and for stabilization issue; due to their low toxicity and easily utility. The most common use of fatty amines in many research work that has been reviewed is as capping and stabilizing agent for the nanoparticles, and that is related to their abilities to stabilize nanoparticles and reduce Ostwald ripening after nanoparticles formation. Moreover, Fatty amines surfactants have been reported in many research works to assist the formation of monodisperse size because they can be adsorbed on the surface of nanoparticles which limit variability in nanoparticles size and also they can form a coat around nanoparticles that prevent agglomeration or aggregation of nanoparticles. Also, other uses that have been addressed for fatty amines as they served as hydrophobic part due to hydrocarbon chain tail. These tails for fatty amines especially those with long hydrocarbon chain more than 12 carbons like; Dodecylamine C12, tetradecylamine C14, hexadecylamine C16 and octadecylamine C18 can be fabricated and conjugated with other molecules or polymers for many nanoparticles synthesis which can help in the self-assembly of nanoparticles. Moreover, due to their high boiling point; they used as solvents and reaction catalyst facilitate the formation of nanoparticles. Finally, fatty amines surfactant used as the ligating compound also assist the formation of nanoparticles.


Author(s):  
M. Kessel ◽  
R. MacColl

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.


Author(s):  
Xiaorong Zhu ◽  
Richard McVeigh ◽  
Bijan K. Ghosh

A mutant of Bacillus licheniformis 749/C, NM 105 exhibits some notable properties, e.g., arrest of alkaline phosphatase secretion and overexpression and hypersecretion of RS protein. Although RS is known to be widely distributed in many microbes, it is rarely found, with a few exceptions, in laboratory cultures of microorganisms. RS protein is a structural protein and has the unusual properties to form aggregate. This characteristic may have been responsible for the self assembly of RS into regular tetragonal structures. Another uncommon characteristic of RS is that enhanced synthesis and secretion which occurs when the cells cease to grow. Assembled RS protein with a tetragonal structure is not seen inside cells at any stage of cell growth including cells in the stationary phase of growth. Gel electrophoresis of the culture supernatant shows a very large amount of RS protein in the stationary culture of the B. licheniformis. It seems, Therefore, that the RS protein is cotranslationally secreted and self assembled on the envelope surface.


1970 ◽  
Vol 6 (1) ◽  
pp. 202-214
Author(s):  
Олена Савченко

У статті розглядається рефлексивна компетентність як інтегративне особистісне утворення, що формується в ході набуття суб’єктом рефлексивного досвіду при застосуванні різних форм рефлексивної активності, спрямованих на розв’язання визначених рефлексивних задач. У структурі рефлексивної компетентності оцінно-мотиваційний компонент виконує наступні функції: оцінку форм рефлексивної активності та її результатів, прогнозування можливих змін у процесі розв’язування проблемно-конфліктних ситуацій, визначення пріоритетних завдань подальшого розвитку себе як суб’єкта рефлексивної активності. На когнітивному рівні функціонує система критеріїв оцінювання власних форм рефлексивної активності, яка характеризується ступенем когнітивної складності, що відображає рівень диференціації та інтеграції системи. Функціонування оцінно-мотиваційного компонента на метакогнітивному рівні забезпечує система здібностей до прогнозування власної активності. Особистісний рівень представлений системою життєвих задач на саморозвиток, які стимулюють суб’єкта докладати зусилля щодо розвитку в себе певних якостей, формування певних вмінь та знань. Розрізненість елементів компонента є індикатором незавершеності процесу формування його внутрішньої структури, низький рівень інтеграції окремих складових не дозволяє системі ефективно компенсувати недорозвинені елементи. Найбільшу вагу у внутрішній структурі оцінно-мотиваційного компонента має показник сформованості системи здібностей до прогнозування власної активності, що підтверджує системотвірну функцію структур метакогнітивного рівня. In the article the reflective competence is seen as an integrative personal formation which develops in the process of acquiring of the reflective experience, when the subject is using various forms of the reflective activity for the solving of specific reflective tasks. In the structure of the reflective competence the value-motivational component performs such functions: an evaluation of forms of the reflective activity and its results, a prediction of the possible changes in the process of solving of the problem-conflict situations, a determining of the priorities for further development of himself as a subject of the reflective activity. The system of the criteria of an evaluating of the reflective activity`s forms functions on the cognitive level of the reflective competence. The level of the cognitive complexity is the basic feature of this system. The predictive abilities` system, that allows to form the expectations of the activity`s results, presents the value-motivational component on the metacognitive level. The system of the life tasks for the self-development, which stimulates the subject to make efforts to develop his own qualities, to form specific skills and knowledge, functions on the personal level. The fragmentation of the elements is an indicator of the incompleteness of the formation of the internal structure of the value-motivational component. The low level of integration of the separate elements does not allow effectively to compensate the functioning of the unformed elements of the system. The index of the formation of the abilities to predict his own activity has the greatest meaning in the internal structure of the value-motivational component. These data confirm the hypothesis about the system-forming function of the metacognitive structures that unite other structures. Thus the development of the predictive abilities will promote the increase of the abilities to the prediction of the others` behavior. An adequate assessment of other people significantly reduces the inconsistency of his own expectations and estimations of others. The development of the predictive abilities creates favorable conditions for the formation of the life tasks for the self-development to increase their value in the system of other tasks


MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3507-3520
Author(s):  
Chunhui Dai ◽  
Kriti Agarwal ◽  
Jeong-Hyun Cho

AbstractNanoscale self-assembly, as a technique to transform two-dimensional (2D) planar patterns into three-dimensional (3D) nanoscale architectures, has achieved tremendous success in the past decade. However, an assembly process at nanoscale is easily affected by small unavoidable variations in sample conditions and reaction environment, resulting in a low yield. Recently, in-situ monitored self-assembly based on ion and electron irradiation has stood out as a promising candidate to overcome this limitation. The usage of ion and electron beam allows stress generation and real-time observation simultaneously, which significantly enhances the controllability of self-assembly. This enables the realization of various complex 3D nanostructures with a high yield. The additional dimension of the self-assembled 3D nanostructures opens the possibility to explore novel properties that cannot be demonstrated in 2D planar patterns. Here, we present a rapid review on the recent achievements and challenges in nanoscale self-assembly using electron and ion beam techniques, followed by a discussion of the novel optical properties achieved in the self-assembled 3D nanostructures.


2018 ◽  
Author(s):  
Claudia Contini ◽  
Russell Pearson ◽  
Linge Wang ◽  
Lea Messager ◽  
Jens Gaitzsch ◽  
...  

<div><div><div><p>We report the design of polymersomes using a bottom-up approach where the self-assembly of amphiphilic copolymers poly(2-(methacryloyloxy) ethyl phosphorylcholine)–poly(2-(diisopropylamino) ethyl methacrylate) (PMPC-PDPA) into membranes is tuned using pH and temperature. We study this process in detail using transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS), and stop-flow ab- sorbance disclosing the molecular and supramolecular anatomy of each structure observed. We report a clear evolution from disk micelles to vesicle to high-genus vesicles where each passage is controlled by pH switch or temperature. We show that the process can be rationalised adapting membrane physics theories disclosing important scaling principles that allow the estimation of the vesiculation minimal radius as well as chain entanglement and coupling. This allows us to propose a new approach to generate nanoscale vesicles with genus from 0 to 70 which have been very elusive and difficult to control so far.</p></div></div></div>


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