Compatibilization of Starch/Synthetic Biodegradable Polymer Blends for Packaging Applications: A Review

The health and environmental concerns of the usage of non-biodegradable plastics have driven efforts to explore replacing them with renewable polymers. Although starch is a vital renewable polymer, poor water resistivity and thermo-mechanical properties have limited its applications. Recently, starch/synthetic biodegradable polymer blends have captured greater attention to replace inert plastic materials; the question of ‘immiscibility’ arises during the blend preparation due to the mixing of hydrophilic starch with hydrophobic polymers. The immiscibility issue between starch and synthetic polymers impacts the water absorption, thermo-mechanical properties, and chemical stability demanded by various engineering applications. Numerous studies have been carried out to eliminate the immiscibility issues of the different components in the polymer blends while enhancing the thermo-mechanical properties. Incorporating compatibilizers into the blend mixtures has significantly reduced the particle sizes of the dispersed phase while improving the interfacial adhesion between the starch and synthetic biodegradable polymer, leading to fine and homogeneous structures. Thus, Significant improvements in thermo-mechanical and barrier properties and water resistance can be observed in the compatibilized blends. This review provides an extensive discussion on the compatibilization processes of starch and petroleum-based polymer blends.

DISCA: high-throughput cryo-ET structural pattern mining by deep unsupervised clustering

Cryo-electron tomography directly visualizes heterogeneous macromolecular structures in complex cellular environments, but existing computer-assisted sorting approaches are low-throughput or inherently limited due to their dependency on available templates and manual labels. We introduce a high-throughput template-and-label-free deep learning approach that automatically discovers subsets of homogeneous structures by learning and modeling 3D structural features and their distributions. Diverse structures emerging from sorted subsets enable systematic unbiased recognition of macromolecular complexes in situ.

Scanning probe microscopic study of P(VDF-TrFE) based ferroelectric nanocomposites

Ceramic and polymer based nanocomponents combine the properties of their constituents, e.g. flexibility, elasticity, polymer reprocessability, hardness typical of glass, wear resistance and high light refraction index. This helps improving many properties of the materials in comparison with the source components. Since recently researchers have been manifesting interest to the properties of complex composite compounds. This is primarily caused by the unique properties of their structures as compared with conventional materials having homogeneous composition. Secondly, this interest is caused by the fact that these compounds may prove to be much cheaper than homogeneous structures provided the physical properties of the composite in a preset range of parameters (temperature, applied field frequency etc.) are identical to those of the respective homogeneous materials. For example, polyvinyl idenfluoride (PVDF) type ferroelectric polymers and copolymers on its basis have found wide application for functional elements of various electromechanic devices in advanced electronics due to their relatively good piezoelectric and pyroelectric properties. The strong random polarization and the formation of polar non-centrosymmetric crystals provide for the high piezoelectric and pyroelectric activity in these crystals. Scanning probe microscopy has been used for study of ferroelectric nanocomposites having different compositions. The matrix specimen for study of local polarization switching at a nanoscale level was vinyl idenfluoride and trifluoroethylene P(VDF-TrFE) copolymer possessing sufficiently high crystallinity. The composite fillers were barium titanate BaTiO3 and deuterized triglycinsulfate DTGS ferroelectric powders and zirconate-titanate lead barium BPZT ceramic powder. We show these materials to show good promise for use in memory cells.

Highly symmetric aperiodic structures -INVITED

The symmetries of periodic structures are severely constrained by the crystallographic restriction. In particular, in two and three spatial dimensions, only rotational axes of order 1, 2, 3, 4 or 6 are possible. Aperiodic tilings can provide perfectly ordered structures with arbitrary symmetry properties. Random tilings can retain part of the aperiodic order as well the rotational symmetry. They offer a more flexible approach to obtain homogeneous structures with high rotational symmetry, and might be of particular interest for applications. Some key examples and their diffraction are discussed.

V. S. PODSHIVALOV’S ESSAYS IN THE MAGAZINE ‘PLEASANT AND USEFUL PASTIME’

The article discusses the essays written by V. S. Podshivalov, the editor of the Moscow University magazine Pleasant and Useful Pastime and a supporter of N. M. Karamzin. The aim of this paper is to study the poetics of the essays and to show their significance in the context of the magazine. Podshivalov’s essays serve as material for researching the problem of the formation of sentimental aesthetics on the Enlightenment basis. The structure and methodology of the article are determined by the task of complex analysis of the text in the aspects of composition, rhetorical devices, themes and literary connections. The essays can be viewed as manifestos of sentimentalism. In his writings, Podshivalov develops a sentimental personality concept. All the essays are shown to be similar in terms of composition, developing a cumulative model where homogeneous structures of motives are gradually added. These structures are usually grouped into triads based on the repetition of key words. Series of such structures are, in turn, compared with each other on the principle of antithesis. The subject matter of the essays is related to the didactic literature of the Enlightenment: they concern traditional themes such as kindness, charity or, conversely, miserliness, cruelty. Satirical types of a miser, a hypocrite or an unfair critic are exposed by contrasting them with sentimental values (a sensitive heart, privacy and a close circle of friends). Podshivalov combines two traditions: Enlightenment didacticism and sentimentalism, transferring didactic issues to the sentimental conceptual sphere. The essays contain reminiscences from the works of N. M. Karamzin published around the same time as the first parts of the magazine. References to Karamzin in the university publication strengthened his moral and literary authority. The aesthetic effect of the essays is achieved by combining two contrasting elements – simplicity of content and complexity of form.

DESIGN OF ETHNOCULTURAL DIVERSITY IN THE CONTEXT OF ETHNOSOCIAL DYNAMICS

The author substantiates the idea of the influence of ethnosocial processes on the dynamics and design of eth-nocultural diversity. It is determinedby the quantitative and qualitative composition of interacting ethnosocial subjects as carriers of ethnocultures, as well as their place in the interethnic community. The expansion and com-plication of ethnocultural diversity makes it relevant to form a more complex management mechanism than in homogeneous structures, otherwise it becomes a threat to the successful development of a community at different levels of its organization.

Green Route for the Removal of Pb from Aquatic Environment

Aim and Objective: Wastewater treatment/remediation is a very important process that has a great environmental and economic impact. Therefore, it is crucial to innovate different methods to remove pollutants of different sources from wastewater. This work was conducted in order to study the removal of lead (Pb+2) from wastewater using microspheres of composites of sodium alginate, cellulose and chitosan, as well as using a cost-effective green route through composites of sodium alginate and dried water hyacinth. Materials and Methods: Molecular modeling at B3LYP/6-31g(d,p) was utilized to study sodium alginate, cellulose and chitosan. Sodium alginate was cross-linked with calcium chloride to form microspheres, then both sodium alginate/cellulose and sodium alginate/chitosan were also crosslinked as 50/50 to form microspheres. The roots of the aquatic plant water hyacinth in dry form were added to the cross-linked sodium alginate for up to 70%. SEM and FTIR were employed to study the surface of the prepared microspheres and their structures respectively. Atomic absorption spectroscopy was used to study the levels of Pb. Results: Molecular modeling indicated that the blending of such structures enhances their ability to bind with surrounding molecules owing to their ability to form hydrogen bonds. SEM results indicated that homogeneous structures of cellulose and chitosan are deformed when blended with sodium alginate, and FTIR confirmed the proper formation of the desired blends. Microspheres from sodium alginate showed the ability to remove Pb+2 from wastewater. SEM indicated further deformation in the morphology with the roughness of sodium alginate/water hyacinth microspheres, while FTIR confirmed the uniform matrices of the microspheres. The removal of Pb+2 was enhanced because of the addition of dried water hyacinth's roots. Conclusion: Modeling, experimental and kinetic data highlight sodium alginate/water hyacinth root as a green route to remediate Pb+2 from wastewater.

Reduction of Homogeneous Pseudo-Kähler Structures by One-Dimensional Fibers

We study the reduction procedure applied to pseudo-Kähler manifolds by a one dimensional Lie group acting by isometries and preserving the complex tensor. We endow the quotient manifold with an almost contact metric structure. We use this fact to connect pseudo-Kähler homogeneous structures with almost contact metric homogeneous structures. This relation will have consequences in the class of the almost contact manifold. Indeed, if we choose a pseudo-Kähler homogeneous structure of linear type, then the reduced, almost contact homogeneous structure is of linear type and the reduced manifold is of type C5⊕C6⊕C12 of Chinea-González classification.