Emulsifier Composition of Solid Lipid Nanoparticles (SLN) Affects Mechanical and Barrier Properties of SLN‐Protein Composite Films

Protein films can be applied to improve food quality and to reduce packaging waste. To overcome their poor water barrier properties, lipids are often incorporated. The function of incorporated lipid depends on the interface between filler and matrix. This study aimed to tailor the properties of a protein–lipid film by designing the oil/water interface to see if the concept of inactive/active filler is valid. Therefore, we varied the emulsifier stabilizing solid lipid nanoparticles (SLN) to promote (via β‐lactoglobulin) or to minimize (via Tween 20) interactions between particle surface and protein. SLN were incorporated into protein films and film properties were determined. Addition of SLN led to significantly decreased water vapor permeability (WVP) of protein films. However, WVP was mainly affected by the emulsifiers and not by the lipid. Protein‐stabilized SLN (BS) replaced a lacking protein in the protein network and therefore did not influence the mechanical properties of the films at ambient temperature. BS‐composite films were temperature sensitive, as lipid and sucrose palmitate melted at temperatures above 40 °C. Tween 20‐stabilized SLN (TS) led to reduced tensile strengths, probably due to perturbative effects of TS and plasticizing effects of Tween 20. Dynamic mechanical analysis showed that TS and Tween 20 increased film mobility. Melting of lipid and emulsifiers, and temperature‐dependent behavior of Tween 20 led to a strong temperature dependence of the film stiffness. By designing the interface, particles can be used to tailor mechanical properties of protein films. Tuned edible films could be used to control mass transfers between foods.     

Poly(lactic acid)/pulp fiber composites: The effect of fiber surface modification and hydrothermal aging on viscoelastic and strength properties

Poly(lactic acid) (PLA)/kraft pulp fiber (30 wt%) composites were prepared with and without a coupling agent (epoxidized linseed oil, ELO, 1.5 wt%) by injection molding. The non-annealed composite samples, along with lean PLA, were exposed to two hydro-thermal conditions: cyclic 50% RH/90% RH at 23 and 50°C, both up to 42 days. The aging effects were observed by size exclusion chromatography, differential scanning calorimetry, dynamic and tensile mechanical analysis, and fracture surface imaging. ELO temporarily accelerated the material's internal transition from viscous to an increasingly elastic response during the aging at 50°C. ELO also slowed down the tensile strength reduction of the composites at 50°C. These observations were explained with the hydrophobic ELO molecules' coupling and plasticizing effects at fiber/matrix interfaces. No effects were observed at 23°C.     

The effect of seasonal variation on automated land cover mapping from multispectral airborne laser scanning data

Multispectral airborne laser scanning (MS-ALS) sensors are a new promising source of data for automated mapping methods. Finding an optimal time for data acquisition is important in all mapping applications based on remotely sensed datasets. In this study, three MS-ALS datasets acquired at different times of the growing season were compared for automated land cover mapping and road detection in a suburban area. In addition, changes in the intensity were studied. An object-based random forest classification was carried out using reference points. The overall accuracy of the land cover classification was 93.9% (May dataset), 96.4% (June) and 95.9% (August). The use of the May dataset acquired under leafless conditions resulted in more complete roads than the other datasets acquired when trees were in leaf. It was concluded that all datasets used in the study are applicable for suburban land cover mapping, however small differences in accuracies between land cover classes exist.     

Immobilization of Trametes hirsuta laccase into poly(3,4-ethylenedioxythiophene) and polyaniline polymer-matrices

The immobilization of Trametes hirsuta laccase (ThL) in the poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) matrices was carried out in order to study the catalytic effect of ThL in different biocathode structures in a biofuel cell application. By using 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) as a mediator compound, the immobilized ThL in both polymer matrices, exhibited catalytic activity for the reduction of oxygen into water. The amount of ThL was adjustable in the PEDOT matrix by controlling the working parameters, such as the charge density used in the electropolymerization of EDOT monomer and the ThL concentration used in the electropolymerization electrolyte. In the PEDOT biocathode structure, the utilization of porous material as the PEDOT supporting template was studied in order to improve the current density generated per unit area/volume. Reticulated vitreous carbon foam (RVC foam) was chosen as the PEDOT supporting template material and the biocathodes were manufactured by in situ entrapment of ThL into PEDOT films polymerized on the RVC foam. These biocathodes possessed a high cathodic open circuit potential and produced a large current density, reaching 1 mA cm⁻³ at 0.45 V when 19.5 μg ml⁻¹ of ThL was used in the electrolyte. The performance of these biocathodes was extremely sensitive to variations in pH and the optimal working pH was around 4.2. The biocathode reserved 80%, 50%, and 30% of the catalytic activity after storage in a +4 °C buffer solution for 1 day, 1 week, and 1 month, respectively. The PANI matrix was prepared in a form of printable ink where ThL was in situ entrapped in the PANI matrix during the laccase activated polymerization of aniline using a chemical batch reactor method. Different amounts of the ThL-containing printable PANI ink were then applied on carbon paper and the performance of the ink was subsequently electrochemically characterized. In this way, not only two different polymer matrices, but also two different matrix manufacturing procedures could be compared.     

Poly(propylene) composite with hybrid nanofiller: Dynamic properties

Mechanical, impact, and relaxation properties of in situ synthesized carbon nanotubes‐polyaniline (CNT‐PANi) hybrid nanoparticle‐filled poly(propylene) (PP) composites with or without an amphiphilic dispersing agent were investigated using tensile testing, notched Charpy impact testing, and dynamical mechanical testing methods. The reference material was MWCNT filled PP composite. Ethyl gallate (EG) was the dispersing agent which realizes high conductivity in PP composites with hybrid filler. Measured properties showed quite similar behavior of CNT‐PANi hybrid and neat CNT filled composites. Addition of 20% EG in PP did not cause essential differences compared to the neat PP. When the dispersing agent was added in filler containing PP composites, remarkable effects were observed, especially in PP‐hybrid composites. Mechanically, these materials had improved tensile properties, but they were brittle compared to the materials without dispersing agent. Dynamic mechanical analysis showed improvement in storage modulus, and in loss modulus the α transition was well observable. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Glass transition and water plasticization effects on crispness of a snack food extrudate

Abstract

A crispy snack model, composed of maltodextrin, wheat flour, salt, and water, with a clearly measurable glass transition was designed and produced by extrusion. The material was used to investigate effects of glass transition and water plasticization on mechanical properties and sensory crispness. Water sorption and the glass transition temperature range were determined gravimetrically and using differential scanning calorimetry (DSC) for samples stored at 0 to 85% relative humidity (RH), respectively. Mechanical properties were determined for extradates rehumidified at 0 to 76% RH. Three sensory panels evaluated crispness intensities of extrudates rehumidified at 33 to 76% RH by either breaking samples with fingers (Finger Task), biting using the incisor teeth (Bite Task), or biting and chewing (Bite‐and‐Chew Task). The extrudate was plasticized by water, as observed from a typical decrease of Tg with increasing water content. Changes in mechanical properties and loss of crispness occurred at an intermediate water activity level coinciding with the extent of plasticization depressing the Tg to below ambient temperature. The changes in mechanical properties and sensory crispness intensities with increasing water activity had sigmoid shapes following the Fermi's model. Loss of crispness as a result of water plasticization is likely to apply to a number of low‐moisture food materials, although various mechanical and sensory properties do not necessarily change in unison as the materials undergo a glass transition.     

Soil nutrient status and revegetation practices of downhill skiing areas in Finnish Lapland — a case study of Mt. Ylläs

Ski slope construction is one of the major anthropogenic factors responsible for ecosystem degradation in mountain areas in Finnish Lapland. Mt. Ylläs has been used as a downhill skiing slope for about 30 years. Until 1992, the ski slopes were kept in their natural condition: there was no removal of vegetation and soil above the tree line. After 1992, Mt. Ylläs went through an extensive construction, the ski slopes were machine-graded and machine-levelled, which caused damage to both vegetation and soil. The aim of the study presented here was to examine nutrient status of various soils on the machine-graded and machine-levelled ski slopes in relation to their potential use as a substrate for revegetation practices.Soil organic matter and nutrient status were analysed in three sites on the slopes of Mt. Ylläs in the tree line zone (transit zone between wooded vegetation and treeless alpine vegetation): (1) reference site on the undisturbed area between the ski-runs (Control); (2) disturbed site on the ski-run area (DSP — ‘DiSturbed Podzol’, DSL — ‘DiSturbed Leptosol’ and DSB — ‘DiSturbed Bare soil’); and (3) Revegetation study Plots established on the ski-runs (RP). The analysis of element concentrations and their relative proportions allow us to conclude that only DSP and DSL can be considered as potentially appropriate for unassisted ecosystem recovery on the ski-runs. Presence of native plant species on these patches supports our conclusion. As a recommendation for revegetation of ski-runs, we propose implementation of substrate composed of upper layer of initial soil. Such substrate can be collected during the construction work on ski slopes or on building sites in the area with similar soils. Uncomposted substrate or at least short period of composting is preferable.     

Effect of accelerated aging on properties of biobased polymer films applicable in printed electronics

The growing interest in sustainable, lightweight, bendable roll-to-roll manufactured printed electronics applied to packaging, textiles or medical healthcare has led to the need for materials that can withstand various environmental conditions. In this work, the studied materials were polyethylene terephthalate (PET), typically used as a substrate for printed electronics, and it was compared to biobased polymeric substrates bio-PET, polylactic acid (PLA), cellulose acetate propionate (CAP) and regenerated cellulose film Natureflex™. Films were exposed for 500 h to heat (50.5°C); heat and humidity (50 RH%); heat, humidity, and light (UV-A 300–400 nm, 42 W/m²) and temperature cycles in the range of −45°C to 65°C. Changes in film transparency and mechanical properties were analyzed. The main findings were that during the exposure to only elevated temperature and temperature with humidity, the analyzed properties were retained in all film materials. UV-A caused less or no changes in Natureflex™, bio-PET and PLA. The most stable in thermal cycling was Natureflex™, CAP, and PET. These results may open new possibilities for biopolymers in printed electronics applications.     

Carboxylate Analogues of Aryl‐Urea‐Substituted Fatty Acids That Target the Mitochondria in MDA‐MB‐231 Breast Cancer Cells to Promote Cell Death

Selective targeting of the tumor cell mitochondrion is a viable approach for the development of anticancer agents because the organelle is functionally different from the mitochondria of normal cells. We recently developed a novel aryl‐urea fatty acid, 16({[4‐chloro‐3‐(trifluoromethyl)phenyl]carbamoyl}amino)hexadecanoic acid ( 1 ) that was found to disrupt mitochondria and to activate apoptosis in MDA‐MB‐231 breast cancer cells. However, there is currently little information on the structural requirements for the activity of compound 1 analogues. The present study evaluated the role of the carboxylic acid group on the anticancer activity of 1 . Bioisosteric replacement of the carboxylate in 1 maintained activity. Thus, like 1 , the sulfonic acid analogue 1‐SA and the oxo‐thiadiazole analogue 1‐OT were also found to target the mitochondrion and to activate cell killing capacity. The hydroxamic acid analogue 1‐HA also killed MDA‐MB‐231 cells, but its onset of action was slower than that of 1‐SA and 1‐OT . In contrast, replacement of the carboxylate with non‐bioisosteric amido and methylamido groups produced analogues that minimally altered mitochondrial function and showed little capacity to decrease tumor cell viability. These findings suggest that the carboxylate moiety in the novel mitochondrially targeted agent 1 is an important determinant of the kinetics and efficacy of anticancer cell activities of compound 1 analogues. Further development of carboxylate‐modified analogues of aryl‐urea fatty acids as potential anticancer agents could now be warranted.