Solution-Mediated Inversion of SnSe to Sb2Se3 Thin-Films

New facile and controllable approaches to fabricating metal chalcogenide thin films with adjustable properties can significantly expand the scope of these materials in numerous optoelectronic and photovoltaic devices. Most traditional and especially wet-chemical synthetic pathways suffer from a sluggish ability to regulate the composition and have difficulty achieving the high-quality structural properties of the sought-after metal chalcogenides, especially at large 2D length scales. In this effort, and for the first time, we illustrated the fast and complete inversion of continuous SnSe thin-films to Sb2Se3 using a scalable top-down ion-exchange approach. Processing in dense solution systems yielded the formation of Sb2Se3 films with favorable structural characteristics, while oxide phases, which are typically present in most Sb2Se3 films regardless of the synthetic protocols used, were eliminated. Density functional theory (DFT) calculations performed on intermediate phases show strong relaxations of the atomic lattice due to the presence of substitutional and vacancy defects, which likely enhances the mobility of cationic species during cation exchange. Our concept can be applied to customize the properties of other metal chalcogenides or manufacture layered structures

ZnO Nanorods via Spray Deposition of Solutions Containing Zinc Chloride and Thiocarbamide

In this work we present the results on formation of ZnO nanorods prepared by spray of aqueous solutions containing ZnCl2and thiocarbamide (tu) at different molar ratios. It has been observed that addition of thiocarbamide into the spray solution has great impact on the size, shape and phase composition of the ZnO crystals. Obtained layers were characterized by scanning electron microscopy (SEM) equipped with energy selected backscattered electron detection system (ESB), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). Small addition of thiocarbamide into ZnCl2solution (ZnCl2:tu = 1:0.25) supports development of significantly thinner ZnO nanorods with higher aspect ratio compared to those obtained from ZnCl2solution. Diameter of ZnO rods decreases from 270 to 100 nm and aspect ratio increases from ∼2.5 to 12 spraying ZnCl2and ZnCl2:tu solutions, respectively. According to XRD, well crystallized (002) orientated pure wurtzite ZnO crystals have been formed. However, tiny ‘spot’—like formations of ZnS were detected on the side planes of hexagonal rods prepared from the thiocarbamide containing solutions. Being adsorbed on the side facets of the crystals ZnS inhibits width growth and promotes longitudinalc-axis growth

Literary works for the promotion of emotional responsivity in younger preschoolers

Kvalifikācijas darba temats: “Literārie darbi jaunākā pirmsskolas vecuma bērnu emocionālās atsaucības sekmēšanai” Darba autore: Olga Volobujeva. Pētījuma mērķis: pētīt jaunākā pirmsskolas vecuma bērnu emocionālās atsaucības veidošanos literāro darbu iepazīšanas procesā. Pētījuma hipotēze: literārie darbi rosina emocionālās atsaucības veidošanas, ja pedagogs: •izvēlas bērnu attīstības pakāpei un interesēm piemērotu tekstu; •piedāvā daudzveidīgas darbības iespējas pēc iepazīšanās ar literāro darbu; •nodrošina labvēlīgu, atbalstošu un drošu vidi grupā. Kvalifikācijas darbs sastāvs no divām daļām, kurās ir ietvertas vairākas apakšnodaļas. Teorētiskajā daļā tiek apskatīts emociju jēdziens dažādu pedagogu, psihologu skatījumā un emocionālās atsaucības veidošanās jaunākā pirmsskolas vecuma bērniem, sniegts psihiskās attīstības raksturojums. Analizēti literārie darbi kā bērnu emocionālās atsaucības veicinātāji. Empīriskajā daļā aprakstīts pētījums par jaunākā pirmsskolas vecuma bērnu emocionālās atsaucības sekmēšanu, izmantojot literāros darbus, dramatizācijas rotaļas, kā arī tiek analizēti iegūtie rezultāti. Darba apjoms: 53 lpp., 4tabulas, 8 attēli, 5 pielikumi, 57 izmantotais avots un literatūra. Atslēgas vārdi: pirmsskola, emocijas, emocionālā atsaucība, literārie darbi.The title of the thesis is "Literary Works for the Promotion of Emotional Responsiveness in Younger Preschoolers". The author is Olga Volobujeva. The aim of the research: to research the development of emotional responsiveness in younger preschool children in the process of getting acquainted with literary works. Research hypothesis: literary works encourage emotional responsiveness if the educator: • chooses texts appropriate to the development and interest of the children; • offers a variety of activities after reading a literary work; • provides a favorable, supportive and secure environment for the group. The thesis consists of two parts, each of which contains several subdivisions. The theoretical part deals with the notion of emotions as represented in the works of various educators and psychologists, and the formation of emotional responsiveness in preschoolers, as well as the characteristics of psychological development. Literary works as promoters of children's emotional responsiveness are analyzed. The empirical part describes the research on the development of emotional responsiveness of preschoolers using literary works and dramatization games, and analyzes the results obtained. The size of the thesis: 53 pages, 4tables, 8 pictures, 5 supplements, 57 references and literature sources list. Keywords: preschool, emotions, emotional responsiveness, literary works

Mechanical properties and self-healing capacity of ultra high performance Fibre Reinforced Concrete with alumina nano-fibres: Tailoring Ultra High Durability Concrete for aggressive exposure scenarios

The effects of alumina nano-fibres are investigated in this paper on the mechanical performance of Ultra High Performance Fibre Reinforced Cementitious Concrete and their efficacy in enhancing the durability of the cementitious composite when exposed to extremely aggressive conditions, with main reference to the stimulated autogenous crack sealing and self-healing capacity. A tailored characterization of the flexural and tensile behaviour of the composite has been first of all performed, also with the purpose of validating an experimental and analytical approach for the identification of the tensile stress vs. strain/crack opening constitutive relationship, which makes use of a purposely conceived indirect tensile test methodology, called Double Edge Wedge Splitting test. Secondly the crack sealing and self-healing capacity have been investigated, considering the recovery of both mechanical flexural performance and durability properties (water permeability) and cross analysing the results for a thorough validation. Microstructural investigations have complemented the aforementioned experimental programme to confirm the efficacy of alumina nano-fibres in enhancing the durability performance of the investigated composites. Superior performance of the mix with alumina nano-fibres with respect to parent companion ones has been highlighted and explained through both a nano-scale reinforcing effects which helps in controlling the cracking process since its very onset as well as through their hydrophilic nature which is likely to foster cement and binder hydration reactions, which can usefully stimulate crack sealing and performance healing recovery at both the macroscopic and mesoscopic fibre-matrix interface) level

A Novel Thermochemical Metal Halide Treatment for High-Performance Sb2Se3 Photocathodes

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The Interaction Pathway in the Mechano-Ultrasonically Assisted and Carbon-Nanotubes Augmented Nickel–Aluminum System

The influence of mechano-ultrasonic activation (MUA) and nano-additives (carbon nanotubes-CNT) on the interaction pathway of nickel–aluminum powder mixture at high heating rates was investigated. The optimum conditions of the mechano-ultrasonic activation, along with the phase and structure formation peculiarities of nickel–aluminum and nickel–aluminum–carbon nanotubes mixtures by thermal analysis method, the so-called high-speed temperature scanner (HSTS), were found out. The optimum duration of mechanical and ultrasonic activation aiming to achieve homogeneous distribution in the agitated mixtures was determined. A shift in characteristic temperatures of MUA mixtures by the influence of both heating rate and ultrasound on the Ni + Al interaction pathway for the mechano-activated (1, 3, 5 min) and 1 wt% CNT containing mixtures was observed. The formation patterns of NiAl + Ni3Al mixture or pure NiAl phase was manifested according to the interaction mechanism (depending on solid–liquid or solid–solid state of intermediates). The effective activation energy values for the Ni + Al exothermic reactions of all studied systems were determined by the isoconversional method of Kissinger