Revealing Nanomechanical Domains and Their Transient Behavior in Mixed-Halide Perovskite Films

Halide perovskites are a versatile class of semiconductors employed for high performance emerging optoelectronic devices, including flexoelectric systems, yet the influence of their ionic nature on their mechanical behavior is still to be understood. Here, a combination of atomic-force, optical, and compositional X-ray microscopy techniques is employed to shed light on the mechanical properties of halide perovskite films at the nanoscale. Mechanical domains within and between morphological grains, enclosed by mechanical boundaries of higher Young's Modulus (YM) than the bulk parent material, are revealed. These mechanical boundaries are associated with the presence of bromide-rich clusters as visualized by nano-X-ray fluorescence mapping. Stiffer regions are specifically selectively modified upon light soaking the sample, resulting in an overall homogenization of the mechanical properties toward the bulk YM. This behavior is attributed to light-induced ion migration processes that homogenize the local chemical distribution, which is accompanied by photobrightening of the photoluminescence within the same region. This work highlights critical links between mechanical, chemical, and optoelectronic characteristics in this family of perovskites, and demonstrates the potential of combinational imaging studies to understand and design halide perovskite films for emerging applications such as photoflexoelectricity.     

Inkjet printing of photocatalytically active TiO2 thin films from water based precursor solutions

In this work, aqueous chemical solution deposition route suited for inkjet printing is used for the synthesis of photocatalytically active TiO₂ coatings. Environmentally friendly precursor solutions with electromagnetic ink-jet printing, allows cheap and simple processing of TiO₂ films on glass. The hydrolysis reaction of water sensitive titanium alkoxide (Ti-alkoxide) precursor is controlled by adding complexing agents as citric acid and triethanolamine prior to water addition, and aqueous stable solutions are achieved. The pH of the solutions is brought to neutral to guarantee flexible processing, avoid damage to substrates and equipment. Solution parameters are adapted to obtain optimal gelation conditions and good jettability. The influence of processing parameters on the phase formation and surface morphology is studied by thermogravimetric analysis and differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The photocatalytic activity of the films is evaluated by the degradation of methyl orange.     

Nanometric Micelles with Photo‐Triggered Cytotoxicity

The development of a photo‐responsive micellar system capable of triggering cell death is reported. Precursors of the micelles are synthesized by connecting a lipophilic chain to a hydrophilic polyethylene glycol via a photo‐labile nitrobenzyl group. The resulting amphiphilic units are self‐assembled in water forming 12 nm micelles that are readily internalized into cells. Upon photo‐irradiation, micelles undergo cleavage and yield a cytotoxic nitrosobenzaldehyde derivative, which significantly inhibits the proliferation of MDA‐MB‐231 cells under standard in vitro conditions.     

Synthesis of ferronickel slag-based geopolymers

This paper deals with the synthesis of geopolymers utilizing ferronickel slag as raw material. The utilized slag is produced in the Greek plant LARCO during the pyrometallurgical treatment of laterites for the production of ferronickel, specifically at the step of the reductive smelting in electric arc furnaces. The performed work includes the optimization of the slag-based geopolymeric system through the study of the effect of the synthesis parameters on the mechanical properties of the produced materials. The structure of geopolymers was determined with X-ray diffractometry (XRD), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The obtained results showed that the ferronickel slag is an excellent raw material for the production of inorganic polymers using the geopolymerization technology. The materials produced under the optimum synthesis conditions were compact and rigid and presented high compressive strength (118 MPa), as well as extremely low water absorption (0.7–0.8%).     

Consumer behaviour in the mobile telecommunications’ market: The individual’s adoption decision of innovative services

Research in the adoption of innovative services in mobile communications markets has not offered a comprehensive explanation of how the individual makes a choice. This article proposes a theoretical framework for the analysis of the adoption decision of innovative mobile services such as mobile TV. The decision to adopt the service can be viewed as a choice based on two cognitive processes of reasoning and referencing, as postulated in behavioural decision making. The framework has both theoretical and practical value. From a theoretical perspective, it illustrates the manner in which referencing and reasoning influence the individual’s decision to adopt innovative services in the mobile telecommunications market. From a practical perspective the framework offers a market analysis tool which can generate useful insights for the vendors.     

Efficacy of different chemicals on shelf life extension of parsley stored at two temperatures

Four different chemical treatments, GA₃, 1‐MCP, essential oils and nano‐Cu, were applied immediately after harvest to Petroselinum crispum (Mill) plants. The efficacy of the above chemicals on shelf life extension of parsley stored at 5 °C and 20 °C was determined by analysing physiological and biochemical factors that determine quality standards of storage fresh parsley. Nonsprayed parsley revealed the highest loss of weight, ascorbic acid, pigments and an enhancement of CO₂ production and lipid peroxidation at 5 °C and 20 °C of storage. Nano‐Cu was more effective for delaying weight loss and revealed a better storage capacity. GA₃, 1‐MCP and essential oils sprays were more effective in ascorbic acid retention at 20 °C than at 5 °C, whereas all substances protect samples from lipid peroxidation. Essential oils were more clearly inhibitory towards both total viable counts and yeast infection. Our results suggest that GA₃, 1‐MCP, essential oils and Nano‐Cu exert their function through different mechanisms during ripening and could provide an effective and complementary means for maintaining high‐quality parsley leaves after harvest.