The Effect of Gradual Fluorination on the Properties of FnZnPc Thin Films and FnZnPc/C60 Bilayer Photovoltaic Cells

Motivated by the possibility of modifying energy levels of a molecule without substantially changing its band gap, the impact of gradual fluorination on the optical and structural properties of zinc phthalocyanine (F_nZnPc) thin films and the electronic characteristics of F_nZnPc/C₆₀ (n = 0, 4, 8, 16) bilayer cells is investigated. UV–vis measurements reveal similar Q‐ and B‐band absorption of F_nZnPc thin films with n = 0, 4, 8, whereas for F₁₆ZnPc a different absorption pattern is detected. A correlation between structure and electronic transport is deduced. For F₄ZnPc/C₆₀ cells, the enhanced long range order supports fill factors of 55% and an increase of the short circuit current density by 18%, compared to ZnPc/C₆₀. As a parameter being sensitive to the organic/organic interface energetics, the open circuit voltage is analyzed. An enhancement of this quantity by 27% and 50% is detected for F₄ZnPc‐ and F₈ZnPc‐based devices, respectively, and is attributed to an increase of the quasi‐Fermi level splitting at the donor/acceptor interface. In contrast, for F₁₆ZnPc/C₆₀ a decrease of the open circuit voltage is observed. Complementary photoelectron spectroscopy, external quantum efficiency, and photoluminescence measurements reveal a different working principle, which is ascribed to the particular energy level alignment at the interface of the photoactive materials.     

Dielectric function and degradation process of poly(triarylamine) (PTAA)

We investigated the optical properties and the degradation process of the organic p-type semiconductor poly(triarylamine) (PTAA) in the mid infrared region. The dielectric function of PTAA was determined in the spectral region of 700 up to 6000 cm⁻¹ by modeling ellipsometric measurements. Due to degradation at 65 °C, PTAA thin films developed carbonyl and hydroxyl features in the infrared spectra. Degradation under 85% RH additionally led to absorption signals of water. A degradation of the bare gold substrates was also observed. For bare gold films, morphology changed upon degradation and adsorption of hydrocarbons from the ambience took place.     

Implementing polarization shift keying over satellite – system design and measurement results

Polarization shift keying (PolSK) is a digital modulation technique using the state of polarization of an electromagnetic wave as the signalling quantity. PolSK comes from fibre communications, where the channel offers two orthogonal states of polarization. This article develops on the idea to adapt this technology to satellite communications, where similar channel conditions exist. For this purpose, a digital PolSK modem was implemented on a programmable logic board. A proposal for constellation design as well as thoughts on synchronization of PolSK over satellite is presented. The modem was used to demonstrate a 16‐state Polarization Shift Keying link over a commercial satellite in K_u band. Measurements have been conducted in a back‐to‐back setup on intermediate frequency and on a K_u band transponder simulator to assess the impact of path‐length differences, carrier recovery and non‐linearity. Copyright © 2015 John Wiley & Sons, Ltd.     

Resistant starch—An accessible fiber ingredient acceptable to the Western palate

Dietary fiber intakes in Western societies are concerningly low and do not reflect global recommended dietary fiber intakes for chronic disease prevention. Resistant starch (RS) is a fermentable dietary fiber that has attracted research interest. As an isolated ingredient, its fine particle size, relatively bland flavor, and white appearance may offer an appealing fiber source to the Western palate, accustomed to highly refined, processed grains. This review aims to provide a comprehensive insight into the current knowledge (classification, production methods, and characterization methods), health benefits, applications, and acceptability of RS. It further discusses the present market for commercially available RS ingredients and products containing ingredients high in RS. The literature currently highlights beneficial effects for dietary RS supplementation with respect to glucose metabolism, satiety, blood lipid profiles, and colonic health. An exploration of the market for commercial RS ingredients indicates a diverse range of products (from isolated RS2, RS3, and RS4) with numerous potential applications as partial or whole substitutes for traditional flour sources. They may increase the nutritional profile of a food product (e.g., by increasing the fiber content and lowering energy values) without significantly compromising its sensory and functional properties. Incorporating RS ingredients into staple food products (such as bread, pasta, and sweet baked goods) may thus offer an array of nutritional benefits to the consumer and a highly accessible functional ingredient to be greater exploited by the food industry.     

Solubility and absorption rate of carbon dioxide into non-respiring foods. Part 3: Cooked meat products

The solubility and diffusion of carbon dioxide into cooked meat products (cooked ham and meat sausage with different pH-levels) was determined at different starting pressures and gas to product volume ratios by monitoring pressure changes over time in a closed chamber at constant temperatures (0, 4, and 8 °C). Good correlation of the CO₂ solubility between the packaging parameters (gas to product volume ratio and initial partial pressure) and the meat products water content was found. The solubility of CO₂ followed Henry’s law and the initial partial pressure of CO₂ influenced the solubility mostly. Only small variations in the diffusion constants and absorption rates were found within the experimental design. A pH difference of 0.5 in the two meat sausage types did not influence either solubility or diffusion significantly.     

Antimicrobial enzymes: Applications and future potential in the food industry

Antimicrobial enzymes are ubiquitous in nature, playing a significant role in the defense mechanisms of living organisms against infection by bacteria and fungi. Hydrolytic antimicrobial enzymes function by degrading key structural components of the cell walls of bacteria and/or fungi, whereas antimicrobial oxidoreductases exert their effects by the generation in situ of reactive molecules. The potential of these enzymes in food preservation is still far from realized at present.     

Vacuolar and extracellular maturation of Saccharomyces cerevisiae proteinase A

The vacuolar aspartyl protease proteinase A (PrA) of Saccharomyces cerevisiae is encoded as a preproenzyme by the PEP4 gene and transported to the vacuole via the secretory route. Upon arrival of the proenzyme proPrA to the vacuole, active mature 42 kDa PrA is generated by specific proteolysis involving the vacuolar endoprotease proteinase B (PrB). Vacuolar activation of proPrA can also take place in mutants lacking PrB activity (prb1). Here an active 43 kDa species termed pseudoPrA is formed, probably by an autocatalytic process. When the PEP4 gene is overexpressed in wild-type cells, mature PrA can be found in the growth medium. We have found that prb1 strains overexpressing PEP4 can form pseudoPrA extracellularly. N-terminal amino acid sequence determination of extracellular, as well as vacuolar pseudoPrA showed that it contains nine amino acids of the propeptide, indicating a cleavage between Phe67 and Ser68 of the preproenzyme. This cleavage site is in accordance with the known substrate preference for PrA, supporting the notion that pseudoPrA is formed by autoactivation. When a multicopy PEP4 transformant of a prb1 mutant was grown in the presence of the aspartyl protease inhibitor pepstatin A, a significant level of proPrA was found in the growth medium. Our analyses show that overexpression of PEP4 leads to the secretion of proPrA to the growth medium where the zymogen is converted to pseudoPrA or mature PrA in a manner similar to the vacuolar processing reactions. Amino acid sequencing of secreted proPrA confirmed the predicted cleavage by signal peptidase between Ala22 and Lys23 of the preproenzyme.     

Use of the selective agar medium CREAD for monitoring the level of airborne spoilage moulds in cheese production

It was investigated if a selective medium for common cheese spoiling moulds (CREAD) could give more relevant information than a general mould medium in hygienic air-sampling in cheese factories. A total of 126 air-samples were taken in six Nordic cheese factories using the general mould medium DG18 and CREAD. The level and genera of air-borne mould was determined. Identification to species-level was performed for a selection of samples. In five cheese factories the mycobiota was dominated by Penicillium spp. and in one cheese factory by Cladosporium spp. The concentration of air-borne moulds varied between the cheese factories ranging from 1 to 270 cfu/m3 on DG18 with a median value of 17. The number of mould colonies was in general lower at CREAD. Identification indicated that CREAD supported growth of common spoilage moulds for cheese, such as Penicillium palitans and P. commune. The mycobiota on DG18 also consisted of moulds not commonly associated with spoilage of cheese, such as Cladosporium spp., P. brevicompactum and P. chrysogenum. Contamination of cheese with mould is periodically a problem in production of semi-hard cheese and the level of air-borne mould is therefore routinely monitored in cheese factories. A clear correlation between the total number of moulds in air and mould growth on products is not always found. The conclusion from the investigation is that it is recommended to use a selective medium for cheese spoilage moulds, such as CREAD in hygienic monitoring.     

Adsorption of arsenic from water using activated neutralized red mud

In this paper activated seawater-neutralized red mud, herein referred to as activated Bauxsol (AB), is used as a novel adsorbent for removing inorganic arsenic (As) from water. The adsorption of As onto AB is studied as a function of contact time, particle size, pH, initial As concentration, AB dosage, and temperature. Kinetic data indicate that the process pseudoequilibrates in 3 and 6 h for As(V) (arsenate) and As(III) (arsenite), respectively, and follows a pseudo-first-order rate expression. Within the range tested, the optimal pH for As(V) adsorption is 4.5, and close to 100% removal can be achieved irrespective of the initial As(V) concentration. Desorption of As(V) is greatest at pH 11.6 where a maximum of 40% can be achieved. In contrast, the optimum pH for As(III) removal is 8.5, and the removal efficiency changes with the initial As(III) concentration. The adsorption data fit the Langmuir isotherm and its linearized form well, with thermodynamic data indicating the spontaneous and endothermic nature of the process. The FITEQL (V.4) and PHREEQC (V.2) computer programs are used to predict As(V) adsorption at various pH values (based on diffuse double layer models). The modeling results fit the experimental results very well and indicate that surface complexation modeling is useful in describing the complex AB surface during the adsorption process. This study shows that As(III) needs to be oxidized to As(V) for a favorable removal using AB and that AB can be a very efficient unconventional adsorbent for removing As(V) from water.