Reversible phase transitions in emulsified nanostructured lipid systems

Aqueous submicron-sized dispersions of the binary monolinolein/water system, which are stabilized by means of a polymer, internally possess a distinct nanostructure. Taking this as our starting point, we were able to demonstrate for the first time that the internal structure of the dispersed particles can be tuned by temperature in a reversible way. Upon increasing the temperature, the internal structure undergoes a transition from cubic via hexagonal to fluid isotropic, the so-called L2 phase, and vice versa. Intriguingly, in addition to the structural changes in topology, the particles expel (take up) water to (from) the aqueous continuous phase when increasing (decreasing) the temperature in a reversible way. At each temperature, the internal structure of the dispersed particles corresponds very well to the structure observed in nondispersed binary monolinolein with excess water. This agreement is independent of any thermal history (including phase transitions), which proves that the structures in the dispersed particles actually are in thermodynamic equilibrium with the surrounding water phase.     

Structural diversity and similar bioactivity in synthetic bicyclononanes

Simple syntheses of diverse bicyclo[3.3.1]nonanes and related compounds as the minimal substructure of bioactive natural products via Michael, aldol, and alkylation reactions from diketones are described herein. The structures of the synthesized compounds were determined by infrared spectroscopy, NMR (¹H and ¹³C), and electrospray ionization–high-resolution mass spectrometry. We also show the in vitro antimicrobial activity against Gram-positive and Gram-negative bacteria. The qualitative analysis has revealed that the new synthesized compounds 5, 6, 9, and 11 present antibacterial properties.     

Striking Features of DPH Electronic Spectra as a Function of Multicomponent Solvent Nature

1,6-Diphenyl-1,3,5-hexatriene is one of the most used fluorescent labels in cell membrane fluidity studies. However, its solubility in aqueous biological media is low and an initial solubilizing step is necessary. In this study, the authors present spectroscopic and computational results in order to explain the striking displacement observed in electronic spectra (absorption and fluorescence) in different solvents. The experimental results were correlated with those obtained by molecular dynamics simulations of multicomponent solutions, which revealed non-homogenous microscopic regions formation in the ternary aqueous DPH solutions.     

Physico-chemical properties investigation of softwood surface after treatment with organic anhydride

Wood originating from a softwood species was subjected to chemical treatment by reaction with succinic anhydride in N, N-dimethylformamide at different concentration values. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis were used to study changes that occurred on a softwood surface. The extent of chemical treatment on softwood was evaluated by determining the weight percent gain values. Thermal properties of modified softwood and the water absorption were also evaluated. The chemical treatment with succinic anhydride influenced the thermal stability of the softwood samples with increasing anhydride concentration levels.      

On the interception of lightning flashes by power transmission lines

The design of the lightning protection system LPS of transmission lines is based on the well known electro-geometrical model. The electro-geometrical model assumes that the first point on a power transmission line that will come within striking distance of the tip of a down-coming stepped leader channel is the strike point of the lightning flash. The model neglects almost all of the physics associated with the lightning attachment.Nowadays, as it is possible to use modern hardware and software tools and several different numerical methods, it is feasible to apply the physics of the discharge process to the study of lightning attachment. Such models take into account the movement of the downward and the resulting upward leaders from different points on the structures under consideration.In this paper, a procedure based on lightning physics was used to analyze the lightning attachment phenomena in EHV transmission lines of 230 kV and 500 kV and the results were compared with the predictions of the electro-geometrical method.     

Thermodynamic study of triclosan adsorption from aqueous solutions on activated carbon

The change in the thermodynamic properties of triclosan adsorption on three activated carbons with the different surface chemistry was studied through immersion calorimetry and equilibrium data; the amount adsorbed of triclosan (Q) during calorimetry was determined and correlated with the energy associated with adsorbate–adsorbent interactions in the adsorption process. It was noted that triclosan adsorption capacity decreases with an increase in oxygenated surface groups. For an activated carbon oxidized with HNO₃ (OxAC), the amount adsorbed was 8.50?×?10^?3 mmol g^?1, for a activated carbon without modification (GAC) Q?=?10.3?×?10^?3 mmol g^?1 and for a activated carbon heated at 1073 K (RAC1073) Q?=?11.4?×?10^?3 mmol g^?1. The adsorbed amounts were determined by adjusting the isotherms to the Sips model. For the activated carbon RAC1073, the immersion enthalpy (ΔH_imm) was greater than those of the other two activated carbons due to the formation of interactions with the solvent (ΔH_immOxAC?=?? 27.3 J g^?1?<?ΔH_immGAC?=?? 40.0 J g^?1?<?ΔH_imm RAC1073?=???60.7 J g^?1). The changes in the interaction enthalpy and Gibbs energy are associated with adsorbate–adsorbent interactions and side interactions such as the adsorbate–adsorbate and adsorbate–solvent interactions.