Atomistic Origin of Lattice Softness and Its Impact on Structural and Carrier Dynamics in Three Dimensional Perovskites

The soft lattices of lead-halide perovskites (LHPs) are responsible for their unique material properties, including polaron formation, defect tolerance, anharmonic vibration, and large electrostrictive response, which result in exotic carrier...

ZnO nanowires growth direction and parameters affecting their surface morphology

ZnO nanowires (or nanorods) have been widely studied due to their unique material properties and remarkable performance in electronics, optics, and photonics. This chapter presents a review of the current research of ZnO nanowires (or nanorods) synthesized by hydrothermal method. We discussed the mechanism of its nucleation and growth taking the effect of different parameters on its growth direction and their final morphology into account. A mixture of zinc nitrate and hexamine as precursor is the most popular. We reported the effect of precursor type and concentration, pH of the growth solution, bath temperature, substrate type and seeded layer, and duration time.

Janus acoustic metascreen with nonreciprocal and reconfigurable phase modulations

Integrating different reliable functionalities in metastructures and metasurfaces has become of remarkable importance to create innovative multifunctional compact acoustic, optic or mechanical metadevices. In particular, implementing different wave manipulations in one unique material platform opens an appealing route for developing integrated metamaterials. Here, the concept of Janus acoustic metascreen is proposed and demonstrated, producing two-faced and independent wavefront manipulations for two opposite incidences. The feature of two-faced sound modulations requires nonreciprocal phase modulating elements. An acoustic resonant unit cell with rotating inner core, which produces a bias by a circulating fluid, is designed to achieve high nonreciprocity, leading to decoupled phase modulations for both forward and backward directions. In addition, the designed unit cell consisting of tunable phase modulators is reconfigurable. A series of Janus acoustic metascreens including optional combinations of extraordinary refraction, acoustic focusing, sound absorption, acoustic diffusion, and beam splitting are demonstrated through numerical simulations and experiments, showing their great potential for acoustic wavefront manipulation.

How chain dynamics affects crack initiation in double-network gels

Double-network gels are a class of tough soft materials comprising two elastic networks with contrasting structures. The formation of a large internal damage zone ahead of the crack tip by the rupturing of the brittle network accounts for the large crack resistance of the materials. Understanding what determines the damage zone is the central question of the fracture mechanics of double-network gels. In this work, we found that at the onset of crack propagation, the size of necking zone, in which the brittle network breaks into fragments and the stretchable network is highly stretched, distinctly decreases with the increase of the solvent viscosity, resulting in a reduction in the fracture toughness of the material. This is in sharp contrast to the tensile behavior of the material that does not change with the solvent viscosity. This result suggests that the dynamics of stretchable network strands, triggered by the rupture of the brittle network, plays a role. To account for this solvent viscosity effect on the crack initiation, a delayed blunting mechanism regarding the polymer dynamics effect is proposed. The discovery on the role of the polymer dynamic adds an important missing piece to the fracture mechanism of this unique material.

Synthesis, Properties, and Selected Technical Applications of Magnesium Oxide Nanoparticles: A Review

In the last few decades, there has been a trend involving the use of nanoscale fillers in a variety of applications. Significant improvements have been achieved in the areas of their preparation and further applications (e.g., in industry, agriculture, and medicine). One of these promising materials is magnesium oxide (MgO), the unique properties of which make it a suitable candidate for use in a wide range of applications. Generally, MgO is a white, hygroscopic solid mineral, and its lattice consists of Mg2+ ions and O2− ions. Nanostructured MgO can be prepared through different chemical (bottom-up approach) or physical (top-down approach) routes. The required resultant properties (e.g., bandgap, crystallite size, and shape) can be achieved depending on the reaction conditions, basic starting materials, or their concentrations. In addition to its unique material properties, MgO is also potentially of interest due to its nontoxicity and environmental friendliness, which allow it to be widely used in medicine and biotechnological applications.

Plasma excited molecular beam epitaxy－proposal and achievements through R&D of compound semiconductor materials and devices－

This paper reviews 35 years of brief history on plasma-excited molecular beam epitaxy, focusing on special values added to conventional Molecular Beam Epitaxy (MBE) through usage of plasma-excited molecular beams. These include low temperature surface cleaning, low temperature growth, selected area re-growth and impurity doping. These technologies are extremely important to realize nano-scale low-dimensional device structures. InN and In-rich InGaN are also highlighted as unique material systems, which plasma-excited MBE process is inevitable to grow. Future prospect of this technology will also be included from the device application viewpoints.

Latviešu literārā biedrība un skolotāja Pētera Zēvalda savāktais jaunvārdu un mazāk zināmo vārdu krājums (1874)

This research is a part of the analysis of the collection of articles of the Latvian Literary Society (Lettisch-literärische Gesellschaft) Magazin, herausgegeben von der Lettisch-Literärischen Gesellschaft (so-called “Magazin”) with special emphasis to the materials important in the history of Latvian language, especially, of the development of terminology in Latvian. This paper deals with the almost forgotten author Pēteris Zēvalds (Peter Seewald) (ca. 1838/1839–1910), a schoolteacher in Jelgava (Mitau) and active contributor of “Magazin” from 1865 to 1877. In 12 sequels (published in eight issues of “Magazin”), he collected 2198 words and expressions from his native place, now Birzgale parish, originally, from the private manor in Linde parish (aus Privatgut Lindenschen Gemeinde in Kurland)). This paper provides a more detailed analysis of two other word collections (both published in 1874 in issue 3 of XV volume of “Magazin”) of Zēvalds. They contained current lexis, including a lot of new terms. The first one is created as a successive excerpt of neologisms and lesser-known words (in Latvian-German comparison) from the weekly newspaper “Baltijas Vēstnesis” (using numbers 44th, 48th, 49th un 51st from 1872 and successive first 49 from 1873, excl. number 9th). There are 467 numbered entries or 495 words in total. Most of the words in Zēvalds’s collection are related to terminological lexis. They can be divided into four groups (indicating the serial number used in the original): (1) terms currently used in the same form or with minor changes of ending (7. greizsirdība, 29. pilnvare, 41. māksla, 33. cēlons, 69. veicināšana, 88. pirmvaloda, 237. izvilktne (= atvilktne), 275. viels); (2) terms which have a different correspondence in modern Latvian (32. valodas=iztirzāšana (= valodniecība), Sprachforschung; 49. lietuve (= lejkanna), Gieskanne; 54. rakstiens (=raksts, dokuments), Schriftstück; 183. atvēles=zīme (= atļauja), Erlaubnißschein; 187. jūras=pāržmauga (= jūrasšaurums), Meerenge); (3) words, that could still be considered as potential terms (11. tiesas=laulība, Zivilehe; 37. sauljumte, Sonnenschirm) and (4) those, which, from the moment of fixation, can be considered occasional words (43. spīdgans, Sternschnuppen, Meteor; 387. muldu=valsts, Reich der Träume; 409. tulpete (= runas=vieta), Katheder, Rednerbühne). Zēvalds’s collection is a unique material that allows identifying the perception of the interested reader about the lexical neologisms in one newspaper. Zēvalds’s second collection of words contains the technical expressions from legal country house purchase agreements. There are 83 numbered entries (in German-Latvian comparison) from the legal contract written in German with a lot of additional conditions and long pay-outs delay. This list (at least the part containing legal terms and terminological word-groups) can be regarded as the first term bulletin in Latvian. The possible addressee of this term list is the parish pastors to whom farmers sought advice on such matters. Publications of the teacher Pēteris Zēvalds is a small but interesting episode in the history of the Latvian language, which has not earned attention so far but provides researchers with interesting material about the lexical development in the 70s of XIX century.

Brillouin and Raman Micro-Spectroscopy: A Tool for Micro-Mechanical and Structural Characterization of Cortical and Trabecular Bone Tissues

Human bone is a specialized tissue with unique material properties, providing mechanical support and resistance to the skeleton and simultaneously assuring capability of adaptation and remodelling. Knowing the properties of such a structure down to the micro-scale is of utmost importance, not only for the design of effective biomimetic materials but also to be able to detect pathological alterations in material properties, such as micro-fractures or abnormal tissue remodelling. The Brillouin and Raman micro-spectroscopic (BRmS) approach has the potential to become a first-choice technique, as it is capable of simultaneously investigating samples’ mechanical and structural properties in a non-destructive and label-free way. Here, we perform a mapping of cortical and trabecular bone sections of a femoral epiphysis, demonstrating the capability of the technique for discovering the morpho-mechanics of cells, the extracellular matrix, and marrow constituents. Moreover, the interpretation of Brillouin and Raman spectra merged with an approach of data mining is used to compare the mechanical alterations in specimens excised from distinct anatomical areas and subjected to different sample processing. The results disclose in both cases specific alterations in the morphology and/or in the tissue chemical make-up, which strongly affects bone mechanical properties, providing a method potentially extendable to other important biomedical issues.

SOME COMMENTS ABOUT THE INFLUENCE OXUS CIVILIZATION IN THEARABIAN GULF

It is known that the Oxus civilization in the Bronze Age, with its unique material culture, interacted with a number of cultural countries: the Indian Valley, Iran, Mesopotamia, Elam and other regions. As a result of these relationships, interactions and interactions are formed. Archaeologists turn to archaeological and written sources to shed light on the historiography of this period. This research is devoted to the history of cultural relations between the Oxus civilization and the countries of the Arabian Gulf in the Bronze Age. The article highlights cultural ties based on an analysis of stamp seals and unique artifacts.Key words: Dilmun, Magan, marine shell, Arabian Gulf, Bahrain, Mesopotamia, Harappa, Gonur, Afghanistan

Silica Microspheres-in-Pores Composite Monoliths with Fluorescence and Potential for Water Remediation

Water pollution is a severe worldwide issue. Constructing advanced porous composite materials has been an efficient route to water remediation via adsorption. In this study, a unique microspheres-in-pores monolithic structure was fabricated. An emulsion-templated polymer monolith was first prepared and silica microspheres were subsequently formed in the porous polymer. A silica precursor was modified with a fluorescent dye and co-condensed with other precursors to fabricate porous composites with fluorescent properties, which were enhanced by the presence of Ag nanoparticles in the polymer matrix. This unique material showed good promise in water remediation by removing organic dyes and heavy metal ions from wastewater via a flowing filter or monolithic column separation.