Preparation and structural characterization of thin-film CdTe/CdS heterojunctions

The structural characteristics of CdTe/CdS thin-film heterojunctions are investigated. The studied heterojunctions were obtained by successive thermal evaporation under vacuum onto unheated SnO2 coated glass substrates of CdS and CdTe films, respectively. The morphological and structural studies of the above mentioned heterojunction component films, in comparison with those of CdS and CdTe films, deposited separately, onto glass substrates, were carried out using transmission electron microscopy, X-ray diffraction and atomic force microscopy techniques

Electrospinning Polyaniline for Sensors

Polyaniline is a conductive polymer (organic metal) with multiple uses as a sensor for mineral acids, ammonia, VOCs etc. The yield of the electrochemical reactions being proportional to the surface area, it is expected that polyaniline nanofibers to provide great opportunities for applications in electronic nanodevices. This article reviews electrospinning configurations (classic, coaxial, with 2 collectors, with rotary collector, with liquid collector etc.) used to obtain 3D structures of electrospun polyaniline, alone or mixed with other polymers, which are used in sensors.publishedVersionPeer reviewe

Structural insights on the selective interaction of the histidine-rich piscidin antimicrobial peptide Of-Pis1 with membranes

Of-Pis1 is a potent piscidin antimicrobial peptide (AMP), recently isolated from rock bream (Oplegnathus fasciatus). This rich in histidines and glycines 24-amino acid peptide displays high and broad antimicrobial activity and no significant hemolytic toxicity against human erythrocytes, suggesting low toxicity. To better understand the mechanism of action of Of-Pis1 and its potential selectivity, using NMR and CD spectroscopies, we studied the interaction with eukaryotic and procaryotic membranes and membrane models. Anionic sodium dodecyl sulfate (SDS) and lipopolysaccharide (LPS) micelles were used to mimic procaryotic membranes, while zwitterionic dodecyl phosphocholine (DPC) was used as eukaryotic membrane surrogate. In an aqueous environment, Of-Pis1 adopts a flexible random coil conformation. In DPC and SDS instead, the N-terminal region of Of-Pis1 forms an amphipathic α-helix with the non-polar face in close contact with the micelles. Slower solvent exchange and higher pKas of the histidine residues in SDS than in DPC suggest that Of-Pis1 interacts more tightly with SDS. Of-Pis1 also binds tightly and structurally perturbs LPS micelles. Of-Pis1 interacts with both Escherichia coli and mammalian cell membranes, but only in the presence of Escherichia coli membranes it populates the helical conformation. Furthermore, ligand-based NMR experiments support a tighter and more specific interaction with bacterial than with eukaryotic membranes. Overall, these data clearly show the selective interaction of this broadly active AMP with bacterial over eukaryotic membranes. The conformational information is discussed in terms of Of-Pis1 amino acid sequence and composition to provide insights useful to design more potent and selective AMPs

Dual-Mode Propellant Properties and Performance Analysis of Energetic Ionic Liquids

Imidazole-based energetic ionic liquids capable of dual-mode chemical monopropellant or bipropellant and electric electrospray rocket propulsion are investigated. A literature review of ionic liquid physical properties is conducted to determine an initial set of ionic liquids that show favorable physical properties for both modes, followed by numerical and analytical performance simulations. Of the ionic liquids considered in this study, [Bmim][dca], [Bmim][NO₃], and [Emim][EtSO₄] meet or exceed the storability properties of hydrazine and their electrochemical proper ties are comparable to [Emim][Im], the current state-of-the-art electrospray propellant. Simulations show that these liquids do not perform well as chemical monopropellants, having 10-22% lower specific impulse due to their lack of oxidizing species. The ionic liquids show acceptable bipropellant performance when burned with standard oxidizers, having specific impulse 6-12% lower than monomethylhydrazine and nitrogen tetroxide combination. Considering these ionic liquids as a fuel component in a binary monopropellant mixture with hydroxyl ammonium nitrate shows 1-3% improved specific impulse over some green monopropellants, while retaining a higher molecular weight, reducing the number of electrospray emitters required to produce a given thrust level. More generally, ionic liquids with oxidizing anions perform well as chemical monopropellants while retaining high molecular weight desirable for electrospray propulsion mission