Cadmium Chalcogenide Nano‐Heteroplatelets: Creating Advanced Nanostructured Materials by Shell Growth,Substitution, and Attachment

The current direction in the evolution of 2D semiconductor nanocrystals involves the combination of metal and semiconductor components to form new nanoengineered materials called nano‐heteroplatelets. This Review covers different heterostructure architectures that can be applied to cadmium chalcogenide nanoplatelets, including variously shaped shell, metal nanoparticle decoration, and doped and alloy systems. Here, for the first time a complete classification of nano‐heteroplatelet types is provided with recommended notations and a systematization of the existing knowledge and experience concerning heterostructure formation techniques, addressing the morphology, optoelectronic and magnetic properties, and novel features of different heterostructures. This Review is also devoted to possible applications of these heterostructures and of one‐component nanoplatelets in multiple fields, including light‐emitting devices and biological imaging.     

Bond graph modelling of chemoelectrical energy transduction

Energy‐based bond graph modelling of biomolecular systems is extended to include chemoelectrical transduction thus enabling integrated thermodynamically compliant modelling of chemoelectrical systems in general and excitable membranes in particular. Our general approach is illustrated by recreating a well‐known model of an excitable membrane. This model is used to investigate the energy consumed during a membrane action potential thus contributing to the current debate on the trade‐off between the speed of an action potential event and energy consumption. The influx of Na+ is often taken as a proxy for energy consumption; in contrast, this study presents an energy‐based model of action potentials. As the energy‐based approach avoids the assumptions underlying the proxy approach it can be directly used to compute energy consumption in both healthy and diseased neurons. These results are illustrated by comparing the energy consumption of healthy and degenerative retinal ganglion cells using both simulated and in vitro data.Inspec keywords: molecular biophysics, biochemistry, bioelectric potentials, biomembrane transport, sodium, neurophysiology, eyeOther keywords: energy‐based bond graph modelling, chemoelectrical energy transduction, biomolecular systems, integrated thermodynamically compliant modelling, chemoelectrical systems, excitable membranes, membrane action potential, energy consumption, healthy neurons, diseased neurons, healthy retinal ganglion cells, degenerative retinal ganglion cells, Na     

Alternative Local Melting-Solidification of Suspended Nanoparticles for Heterostructure Formation Enabled by Pulsed Laser Irradiation

Phase formation by pulsed laser irradiation of suspended nanoparticles has recently been introduced as a promising synthesis technique for heterostructures. The main challenge still lingers regarding the exact mechanism of particle formation due to the non-equilibrium kinetic by-products resulting from the localized alternative, fast, high-temperature nature of the process. Here, the authors analyze the bond breaking/formation of copper or copper (II) interfaces with ethanol during the absorption of pulses for Cu-CuO-Cu₂O formation applicable as an electrocatalyst in ethanol oxidation fuel cells. This study includes but is not limited to, a comprehensive discussion of the interaction between nano-laser pulses and suspension for practical control of the synthesis process. The observed exponential and logarithmic changes in the content of heterostructures for the CuO-ethanol and Cu-ethanol samples irradiated with different fluences are interpreted as the dominant role of physical and chemical reactions, respectively, during the pulsed laser irradiation of suspensions synthesis. It is also shown that the local interface between dissociated ethanol and the molten sphere is responsible for the oxidative/reductive interactions resulting in the formation of catalytic-augmented Cu³⁺ by-product, thanks to the reactive bond force field molecular dynamics studies confirmed by ab-initio calculations and experimental observations.     

EVALUATION OF UV DOSE IN FLOW-THROUGH REACTORS FOR FRESH APPLE JUICE AND CIDER

High absorptivity and turbidity interfere with the UV disinfection of apple cider. Three different configurations of flow-through UV reactors were evaluated to overcome this interference. Two approaches were employed: use of an extremely thin film UV reactor and increasing the turbulence within a UV reactor. Multiple-lamp UV reactors including the thin-film laminar flow “CiderSure” (8 lamps) and turbulent flow “Aquionics” (12 lamps) and annular single-lamp “UltraDynamics” reactor were studied. UV disinfection performance in laminar and turbulent flow reactors was compared by evaluation of UV dose delivery. UV fluence rate (irradiance) distribution was calculated using the multiple point source summation method. E. coli K12 was used as a target bacterium in a bioassay, and the log reduction per one pass was determined for each UV reactor. Finally, the UV decimal reduction dose (D₁₀) was calculated by dividing the average UV fluence by log bacterial reduction per pass. Variations of the UV decimal dose were observed with various designs of UV systems. The least inactivation of E. coli K12 but the highest UV decimal reduction dose, ranging from 90 to 150 mJ/cm², was observed in the Aquionics UV reactor in apple cider with apparent absorption coefficient (a) of 5.7 mm^-1. The lower value of UV decimal reduction dose of 7.3-7.8 mJ/cm² was required for inactivation of E. coli K12 in malate buffer and apple juice in the annular single-lamp UltraDynamics reactor. However, the decimal reduction dose for E. coli K12 in apple cider was significantly higher, about 20.4 mJ/cm². Similar UV decimal reduction doses from 25.1 to 18.8 mJ/cm² for inactivation of E. coli K12 were observed in the thin-film 'CiderSure' UV reactor in apple cider with identical absorption coefficient. Mathematical modeling of UV irradiance can improve the evaluation of UV dose delivery and distribution within the reactors.     

Role of the solid electrolyte composition on the performance of a polymeric memristor

The role of the solid electrolyte composition on the properties of an electrochemically controlled conducting polymer–electrolyte junction (organic memristor) was investigated, with the purpose of optimizing its memory properties and non-linear characteristics. Along with electrical measurements, SEM imaging and FTIR characterization were performed in order to correlate the results with the film morphology and differences in the vibrational spectra, respectively. Best results were obtained with a slightly acidic nature of the electrolyte dopant which allows to avoid the secondary doping of the structures and shifts the reduction potentials to negative values. The first achievement simplifies the technology of the memristor fabrication, while the second one allows to work in the pulse mode without any dc offset of the input signal as well as to fabricate complex networks of such elements without any risk to exclude some elements from the process of the formation of signal transfer pathways.     

A parallel solution to the HIP game based on genetic algorithms

In this piece of research, genetic algorithms are put forward for solving the HIP game. The proposed parallel approach manipulates candidate solutions via mutation and selection; no crossover has been employed. The population is limited to one candidate solution per generation, thus keeping the computational complexity of the approach to a minimum. It is shown that the proposed approach is superior to the approaches reported in the literature: Solutions are more speedily provided, whereas the frequency of finding a solution is significantly higher; furthermore, considerably more complex instances of the HIP game are successfully solved. © 2009 Wiley Periodicals, Inc.     

Synthesis,characterization and antibacterial activity studies of poly-{styrene-acrylic acid} with silver nanoparticles

This work reports the preparation and characterization of copolymer poly-{styrene-acrylic acid} with monomeric ratio of styrene/acrylic acid of 9:1 using benzoyl peroxide as initiator and furthermore filled with nanosilver (25 ppm and 50 ppm) in water/acetone (1:40 v/v). The nanosilver emulsion was obtained from chemical reduction using NaBH₄ as reducing agent and sodium citrate as the stabilizer. The preparation of nanosilver emulsion was monitored by the appearance of a Plasmon Resonant Absorption band in a UV–visible spectrophotometer and the particles sizes were observed through TEM. Microbiological studies were performed to investigate the antimicrobial activity of this new material against the microorganisms Escherichia coli (ATCC-25922) and Staphylococcus aureus (ATCC-6538), used as reference strains. The antimicrobial activity of the poly-{styrene-acrylic acid} filled with nanosilver was confirmed by the presence of an inhibition halo of the bacterial growth in seeded culture media, but was not found with the poly(styrene-acrylic acid) alone. The present work suggests that silver ions are released from the polymeric matrix to the culture media and have the ability to tune the Ag⁺ ions released by controlling the amount of Ag nanoparticles embedded in the composite.     

Structural and morphological investigation of magnetic nanoparticles based on iron oxides for biomedical applications

The present work reports the synthesis, characterization and properties of magnetic iron oxide nanoparticles for biomedical applications, correlating the nanoscale tunabilities in terms of size, structure, and magnetism. Magnetic nanoparticles in different conditions were prepared through thermal decomposition of Fe(acac)₃ in the presence of 1,2 hexadecanodiol (reducing agent) and oleic acid and oleylamine (ligands) in a hot organic solvent. The 2,3-dimercaptosuccinic acid (DMSA) was exchanged onto the nanocrystal surface making the particles stable in water. Nanoparticles were characterized by X-ray diffraction (XRD) measurements, small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Preliminary tests of incorporation of these nanoparticles in cells and their magnetic resonance image (MRI) were also carried out. The magnetization characterizations were made by isothermal magnetic measurements.     

Non-visual game design and training in gameplay skill acquisition – A puzzle game case study

This paper reports the results of a study on the design and evaluation of the game and techniques which allow puzzles to be played in the absence of visual feedback. We have demonstrated that a camera-mouse can be used successfully for blind navigation and target location acquisition within a game field. To gradually teach the players the sequential learning method was applied. Blind exploration of the gamespace was augmented with sticky labels and overview sound cues, verbal and non-verbal, which can significantly reduce the cognitive load and facilitate mental matching and integration. The full-sticky labels technique does not require fine motor skills and allows a user to gain control over the game with a minimum level of skills. With the vertical sticky labels technique training was focused on the development of accurate head movements only on a horizontal plane. With practice, the players can use the non-sticky labels technique. After 240 trials (3–4 h), the cumulative experience of the blindfolded players was increased 22.5–27 times compared to the initial 10 trials.