Types Of Structural Transformations Research Articles

Growth pathways of Cu shells on Au and AuCu seeds: interdiffusion, shape transformations, strained shells and patchy surfaces.

The growth of AuCu nanoparticles obtained by depositing Cu atoms on starting seeds of pure Au and on mixed AuCu seeds is studied by molecular dynamics simulations. Depending on the shape of the seed, its composition and the growth temperature, different growth pathways are observed, in which several types of structural transformations take place. The final growth structures comprise Au@Cu core@shell arrangements as well as Janus-like structures with patchy surfaces. The results of the growth simulations are rationalized in terms of the activation of different diffusion processes, both on the surface and inside the growing clusters. These diffusion processes regulate structural transitions between different motifs and the occurrence of dewetting phenomena. The simulation results show that depositon of Cu atoms on pure Au or mixed AuCu seed can be an effective tool for producing clusters with uncommon surface atom arrangements of potential interest for catalysis.

Cross-validation strategies in QSPR modelling of chemical reactions

ABSTRACT In this article, we consider cross-validation of the quantitative structure-property relationship models for reactions and show that the conventional k-fold cross-validation (CV) procedure gives an ‘optimistically’ biased assessment of prediction performance. To address this issue, we suggest two strategies of model cross-validation, ‘transformation-out’ CV, and ‘solvent-out’ CV. Unlike the conventional k-fold cross-validation approach that does not consider the nature of objects, the proposed procedures provide an unbiased estimation of the predictive performance of the models for novel types of structural transformations in chemical reactions and reactions going under new conditions. Both the suggested strategies have been applied to predict the rate constants of bimolecular elimination and nucleophilic substitution reactions, and Diels-Alder cycloaddition. All suggested cross-validation methodologies and tutorial are implemented in the open-source software package CIMtools (https://github.com/cimm-kzn/CIMtools).

ДИЗАЙН СУЧАСНОГО КОСТЮМА НА ОСНОВІ АСОЦІАТИВНИХ ТРАНСФОРМАЦІЙ ТЕКТОНІЧНОЇ СТРУКТУРИ НАРОДНОГО ОДЯГУ

Improving the design process of modern clothes and determining the sign-symbolic functions of costume, inspired by ethnic motives, by studying methods of the associative transformation of the folk costume tectonic structure based on the use of various types of structural transformations. System-informational, visual-analytical research methods are used in the work. Systematic and structural analyses of the artistic and compositional elements transformations in the shaping of a modern costume based on associative conversion is applied.Results. Based on the investigation, the interconnection between associative signs and structural building of modern women’s clothes, designed upon a folk costume construction basis, has been determined. The research of the most expressive elements of traditional clothes has been carried out with the purpose to determine symbolic functionality of a contemporary costume. Principles of project implementation of associative structural transformations of costume forms, spatial elements layout and order of their placement using different types of tectonic transformation have been determined, and classification of structural transformations has been developed. Scientific novelty lies in the development of modern costume designing methods based on the forms and structure of traditional folk clothes. This makes it possible to determine the variability of the use of relationships of morphological and associative transformations of the object and improving the design processes of new promising costume forms. The results of scientific work can be used in the practical activity of costume designers in order to develop promising collections of modern clothes for contests and exhibitions.The results allow to optimize the design process of modern clothing models.

MECHANISMS OF INFLUENCE OF ORGANIZATIONAL AND ADMINISTRATIVE TRANSFORMATION ON THE DEVELOPMENT OF INDUSTRIAL ENTERPRISES

The scientific provisions on the use of transformation procedures in the organizational and managerial field of the enterprise activity are sufficiently substantiated in the scientific works of well-known foreign and domestic scientists. In addition to transformational models that offer a specific sequence of stages, general approaches to organizational transformations are recently developed in the theory and practice. These approaches describe the philosophy of the process. However, the theoretical basis for the emergence of the necessity and the prospect of organizational transformations, in particular in the form of restructuring, has certain gaps and inaccuracies, which often lead to a different interpretation of the necessity and procedural security of this process in the activities of industrial enterprises. The conducted analysis of theoretical and methodical aspects of transformation processes in the organizational and managerial sphere of activity of industrial enterprises allowed identifying and justifying the criteria for the success of organizational transformations and the specific sequence of stages of their implementation. The definition of content of the category "enterprise restructuring" is proposed in the context of organizational transformation. The scheme of the process of implementation of the corresponding organizational and managerial transformations, which involves the use of new tools and methods of organization of activity and enterprise management system in order to ensure optimization of economic activity, is constructed. The scientific novelty of the results is that the methodological provisions, which are in the article, allow us to determine possible directions and types of structural transformations; to choose the controlled factors that influence the size of the market value of the enterprise by types of transformations in the organizational and managerial sphere; to present the structural model of planning and implementation of enterprise restructuring, which is consistent with the idea of the process of structural changes of the enterprise in relation to adaptation to the external environment and application of the latest management concepts; to present a structural scheme for evaluating the effectiveness of the restructuring, aimed at the development of the enterprise. The developed approaches to determining the need for transformation processes of organizational and managerial transformation and a scheme for evaluating the effectiveness of restructuring can be used by specialists to make grounded decisions aimed at the development of industrial enterprises.

Industrial Policy for a European Industrial Renaissance. A Few Reflections

This paper raises and attempts to address three questions that add to the recent debate on industrial policies to promote a European “industrial renaissance”. We ask (i) What type of de-industrialisation represents a threat for Europe? (ii) What type of structural change can industrial policy steer in a context of increasing international fragmentation of production, both across European countries and worldwide? (iii) What type of industrial policy shall we advocate, that goes beyond the manufacturing sectors? With no pretence to provide all the answers or yet another wish list of policy tools, we argue that we are “doomed to choose” what type of structural transformation is Europe in need of, in a context of harsher global competition from the emerging countries; of staggering income polarisation within Europe itself; of relentless international fragmentation of production processes. First, we claim that industrial policy should target sectors and segments of value chains that support the manufacturing sector and not necessarily represent a hollowing out of the industrial base. Second, industrial policy should target structural transformation alongside large “missions” and learn from classical debates on industrialisation-led development. Interventions should therefore go beyond the traditional vertical versus horizontal tools distinction and complement a “mission oriented” plea with other tools, to avoid yet another “one size fits all” approach.

Reaction Pathway and Free Energy Profile for Prechemical Reaction Step of Human Butyrylcholinesterase-Catalyzed Hydrolysis of (−)-Cocaine by Combined Targeted Molecular Dynamics and Potential of Mean Force Simulations

Combined targeted molecular dynamics (TMD) and potential of mean force (PMF) simulations have been carried out to uncover the detailed pathway and determine the corresponding free energy profile for the structural transformation from the nonprereactive butyrylcholinesterase (BChE)-(-)-cocaine binding to the prereactive BChE-(-)-cocaine binding associated with the (-)-cocaine rotation in the binding pocket of BChE. It has been shown that the structural transformation involves two transition states (TS1(rot) and TS2(rot)). TS1(rot) is mainly associated with the deformation of the nonprereactive complex, whereas TS2(rot) is mainly associated with the formation of the prereactive complex. It has also been demonstrated that the A328W/Y332G mutation significantly reduces the steric hindrance for (-)-cocaine rotation in the binding pocket of BChE and, thus, decreases the free energy barrier for the structural transformation from the nonprereactive binding to the prereactive binding. The calculated relative free energy barriers are all consistent with available experimental kinetic data. The new mechanistic insights obtained and the novel computational protocol tested in this study should be valuable for future computational design of high-activity mutants of BChE. The general computational strategy and approach based on the combined TMD and PMF simulations may be also valuable in computational studies of detailed pathways and free energy profiles for other similar mechanistic problems involving ligand rotation or another type of structural transformation in the binding pocket of a protein.

Collision-induced annealing of octanethiol self-assembled monolayers by high-kinetic-energy xenon atoms

Collisions with high-energy xenon atoms (1.3 eV) induce structural changes in octanethiol self-assembled monolayers on Au(111). These changes are characterized at the molecular scale using an in situ scanning tunneling microscope. Gas-surface collisions induce three types of structural transformations: domain boundary annealing, vacancy island diffusion, and phase changes. Collision-induced changes that occur tend to increase order and create more stable structures on the surface. We propose a mechanism where monolayer transformations are driven by large amounts of vibrational energy localized in the alkanethiol molecules. Because we monitor incremental changes over small regions of the surface, we can obtain structural information about octanethiol monolayers that cannot be observed directly in scanning tunneling microscopy images.

Primary recrystallization mechanisms in ceramic materials

Data on the mechanisms of primary recrystallization in covalent type ceramics under temperature-and-pressure treatment are generalized and discussed. There are three types of structural transformations governing nucleation during primary recrystallization. I. Formation of intragrain boundaries. As a result of plastic shears boundaries appear to be kinked due to dislocation pile-ups (materials based on 2H BN, 6H SiC). With deformation by total dislocations the boundaries arise as a result of dynamic recovery due to rebuilding of dislocation pile-ups (AlN, β-Si3N4, TiB2). II. Twinning. This structural transformation promotes the formation of recrystallization nuclei in the following cases: a) with insertion of lattice dislocations into the boundaries of strain-induced twins; b) with formation of annealing twins; c) with development of multiple twinning near grain boundaries (3C BN). III. Structural transformations in migrating boundaries: a) splitting of boundaries and ternary junctions (3C BN); b) local bulging of boundaries (3C BN); c) generation of high-angle and platelet twins (3C BN); d) plastic rotation of material microvolumes near grain boundaries (3C BN, SiC).

Atomic Structural Transformations on Clean Metal Surfaces

Two types of structural transformations which occur on clean, single-crystal surfaces have been investigated in atomic detail at Sandia National Laboratories. The restructuring of surfaces from ''bulk-terminated'' to ''reconstructed'' structures and the configuring of cluster nuclei between two-dimensional islands and one-dimensional chains have been examined by field ion microscopy, a technique which provides direct images of individual surface atoms. Observations of the bulk-terminated (unreconstructed) Pt (110) surface with the field ion microscope surface indicate that atoms in the topmost layer are aligned in rows adjacent to each other. The unreconstructed surface is produced by a process known as field evaporation (i.e. the removal of atoms by a high electric field at temperatures of 77K), which typically leaves a surface with the bulk-terminated structure. This metastable surface is found to transform to the equilibrium, reconstructed surface at temperatures above 300K.

Potassium Fixation by Clay Minerals during Hydrothermal Treatment

AbstractThe amount of K fixed in K- and Ca-saturated montmorillonite, vermiculite (trioctahedral), rectorite-type and IMII-ordered mica/montmorillonites was measured as a function of time (1–64 days), temperature (25o-300°C), pH (6.0, 9.7, and 10.7), and K-concentration (0.02 and 1.0 M) in solution. The amount of K fixed by the clays generally increased with increasing temperature, pH, and K-concentration and reached saturation in response to each experimental condition in 5 or 6 days. The K-montmorillonite and K-vermiculite fixed considerable amounts of K even at 25°C. Fixed K in montmorillonite increased with an increase of the layer charge which is also influenced significantly by the interlayer cation. In detail, the behavior in K-fixation was specific to each clay.The type of structural transformation with K-fixation was different for each clay. In montmorillonite, especially, the type of transformation was related to the cationic composition of the system; in K homoionic system, montmorillonite transformed rapidly into illite/montmorillonite with about 40% expandable layers at 300°C and in a mixed cation system with Ca and K, it reacted gradually to random illite/montmorillonites with increasing temperature. These data indicate that the cation-exchange process of a natural pore solution plays an important role in the gradual transformation of detrital montmorillonite to illite.

Brillouin-scattering at transitions of polymer films

Abstract The hypersonic behaviour of differently prepared polymer films has been investigated below and above the melting temperature. For partially crystallizing polymers a new type of structural transformation within the melt will be reported. For strongly oriented solid polyethylene a phase separating between the crystallizing and the non-crystallizing part has been found.