How a riparian landscape finds form and comes alive

If we consider riparian areas as landscapes it means that we consider them as entities whose survival depends on ecological as well as on cultural sustainability. Ecological sustainability requires people’s understanding of the role of both diversity and connectivity of riparian areas. Cultural sustainability requires people’s attention and care towards diversity and connectivity. It is argued that interaction between ecological and cultural sustainabilities governs riparian management, and that we still have to promote such an interaction.     

Electrical simulations of doped multilayer organic light‐emitting diodes (OLEDs) under temperature stress for high current densities

Abstract— This work aims at explaining and predicting the influence of the thickness of organic materials, dye doping, and space‐charge effects on charge‐carrier transport at different operating temperatures for high current densities (50 ≤ J ≤ 7000 mA/cm²). For the purpose of determining these influences, current‐voltage characteristics for typical electrically doped multilayer organic light‐emitting diodes (OLEDs) have been simulated. The results of the simulations concur with experimental data.     

The viscosity of diesel oil and mixtures with straight vegetable oils: Palm, cabbage palm, cotton, groundnut, copra and sunflower

The feed back experience of using straight vegetable oil (SVO) as a fuel in the existing diesel engines evidences the need for fitting several physical properties, among them the fuel viscosity. An empirical modelling is proposed in order to interpolate viscosity to any kind of diesel oil/SVO blend. This model is fitted on an experimental viscosity database on blends, varying the SVO mass proportion in the blend, the blend temperature between cloud point and 353 K, and including six vegetable oils varying the fatty acids composition. Extrusion rheology was also checked by varying the pressure drop. Measurements show that blends behave Newtonian.     

A comparison of variate pre-selection methods for use in partial least squares regression: A case study on NIR spectroscopy applied to monitoring beer fermentation

This work investigates four methods of selecting variates from near-infrared (NIR) spectra for use in partial least squares (PLS) regression models to predict biomass and chemical changes during beer fermentation. The fermentation parameters studied were ethanol concentration, specific gravity (SG), optical density (OD) and dry cell weight (DCW). The four selection methods investigated were: Simple, where a fingerprint region is chosen manually; CovProc, a covariance procedure where variates are introduced based on the magnitude of the first PLS vector coefficients; CovProc–SavGo, a modification to CovProc where the window size of a Savitzky-Golay filter applied to the spectra is also optimised; and genetic algorithm (GA), where variates are selected based on the frequency of appearance in 8-variate multiple linear regression models found from repeated execution of the GA routine. The analysis found that all four methods produced good predictive models. The GA approach produced the lowest standard error in prediction (SEP) based on leave-one-out cross-validation (LOO-CV), although this advantage was not reflected in the standard error in validation values, SEV, where all four models performed comparably. From this work, we would recommend using the Simple approach if a suitable fingerprint region can be identified, and using CovProc otherwise.     

PNIPAM: a thermo-activated nano-material for use in optical devices

In this paper we describe the use of thermo-activated PNIPAM nano-material in optical switching devices. In other publications, the PNIPAM is used either as a carrier for crystalline colloidal array self-assemblies or as micro-particles that serve as pigment bags. In this publication we use a simpler-to-fabricate pure PNIPAM solution in a semi-dilute regime. The PNIPAM devices produced are transparent at temperatures below a critical temperature of 32°C and become diffusing above this temperature. We show that at 632 nm the transmission through the devices is about 75% in the transparent state while the additional attenuation achieved in the diffusing state is of the order of 38 dB. The experimental fall and rise times obtained are large (about 300 ms and 5 s, respectively) due to the non-optimised thermal addressing scheme. In addition, spectral measurements taken in the infrared spectrum (700–1,000 nm) demonstrate that the cell response is flat over a large portion of the infrared spectrum in both the transparent and the diffusing states.     

Electro-conductive porous ceramics prepared by chemical vapor infiltration of TiN

Using pressure-pulsed chemical vapor infiltration (PCVI) method, TiN was partially infiltrated at 850 °C from gas system of TiCl₄ (1%)–N₂ (10%)–H₂ into the highly porous carbon substrates prepared by the carbonization of cotton-wool, filter paper, and wood at 1,000 °C in Ar for 4 h. After 10,000 pulses of PCVI, electro-conductive porous ceramics having the three-dimensionally continuous current paths were obtained, which had the porosity of 80% and more, the resistivity of 10⁻⁵–10⁻⁶ Ω m, and the average pore sizes of 10–40 μm. The geometric surface area per unit volume of the sample was higher than that of the conventional foil-type current collector for lithium-ion battery. The surface area showed the highest value for the sample obtained from carbonized wood substrate.     

Polyglyceryl amines as surfactants I: Symmetrical polyglyceryl amines and aqueous solution properties

The synthesis and aqueous micellar properties of three series of homologous symmetrical polyglyceryl alkyl amines are described. They are synthesized from nucleophilic opening of the appropriate oxirane in nearly quantitative yields. Surface tension measurements indicate that these molecules have wide-ranging amphiphilic properties. Surface tension curves show that diglyceryl amines have a different behavior from the tetra (TGA) and octa (OGA) glyceryl amines. They appear more hydrophilic although they contain fewer hydroxy groups. Moreover, only TGA and OGA show a relation between alkyl chain number and the surface tension at the critical micelle concentration, which is attributed to the polar-head structural differences.     

Identification of thrust force models for vibratory drilling

Among the scientific problems in drilling, determining thrust forces for any drill geometry and any workmaterial remains an issue. This question is especially critical in the context of the self-vibratory drilling (SVD) technology, since thrust force governs the trajectory of cutting lips. In order to predict the dynamical behaviour of the self-vibratory drilling head (SVDH), a numerical simulator has been developed in the laboratory. In order to predict the relevant behaviour of the SVD operations, a good accuracy of the thrust force model is highly necessary. The aim of the paper is to propose an experimental methodology to identify a thrust force model for one pair “drill–workmaterial” depending on the uncut chip thickness. This methodology proposes to divide cutting edges into several parts in order to define the local contribution of this part to the macroscopic thrust force. Local models are identified during the penetration of the drill. From a limited number of experiments with various feeds, it becomes possible to identify all the coefficients of an accurate thrust force model.     

Volatile compounds produced by Bacillus species alkaline fermentation of bambara groundnut (Vigna subterranean (L.) Verdc) into a dawadawa-type African food condiment using headspace solid-phase microextraction and GC × GC–TOFMS

The reports on the volatile compounds of a dawadawa-type African food condiment produced from the alkaline fermentation of bambara groundnut (Vigna subterranea (L.) Verdc.) using Bacillus starter cultures are limited. Volatile compounds were isolated from dawadawa-type condiments using headspace solid phase microextraction and analysed by comprehensive gas chromatography coupled to time of flight mass spectrometry. Acids, aldehydes and alcohols accounted for over 70% of the volatile compounds produced in the Bacillus fermented samples. B. subtilis subsp. subtilis SFBA3 produced the highest content of acids (4969.60 µg kg^?1), while the highest content of aldehydes (2811.90 µg kg^?1) and alcohols (1247.60 µg kg^?1) was detected with Bacillus cereus PALB7 and Bacillus licheniformis OALB2, respectively. Sulphur-containing compounds concentration (85.80 µg kg^?1) was highest for Bacillus amyloliquefaciens SFBA2. Maximum 2-methyl butanoic acid and 3-methyl butanoic acid concentrations, indicative of typical dawadawa aroma, were produced by B. subtilis subsp. subtilis SFBA3.