Influence of the structure of polymer fiber composites on the analysis of the zeta potential

This article addresses the questions about the influence of surface area, roughness, and sample mounting on the zeta potential analysis. A series of knitted yarns and fabrics of cotton and modacryl and their blends represent a real‐life model system to study these effects. The combination of the natural cotton and the man‐made modacryl makes possible to study the effect of the different origin for surface and interfacial charge and the surface area‐weighted contributions to the average zeta potential of a chemically heterogeneous composite material. In our study, two measuring cells of the SurPASS electrokinetic analyzer were used, namely the Cylindrical Cell and the Adjustable Gap Cell. Comparison of the results obtained in two different measuring cells was related to the measured material. We used the Cylindrical Cell for both the zeta potential analysis of yarn and knitted fabrics and compared these results with data obtained for knitted fabrics using the Adjustable Gap Cell. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46227.     

Recent Developments and Trends in Powder Injection Molding

Injection molding is a productive and widely used technology for shaping plastics. The use of this shaping technique to metal and ceramics powders is termed powder injection molding (PIM). This process combines a certain quantity of a polymer with a metallic or ceramic powder to form a feedstock that can be molded. After shaping, the polymeric binder is extracted and the powder is sintered. When proper powder size or/and its distribution are used, sintered densities of 95% or more, often to near-theoretical densities, are reached and the mechanical properties are, therefore, generally superior to those of traditional PM parts.     

Predicting the duration of emotional experience: Two experience sampling studies.

The authors present 2 studies to explain the variability in the duration of emotional experience. Participants were asked to report the duration of their fear, anger, joy, gratitude, and sadness episodes on a daily basis. Information was further collected with regard to potential predictor variables at 3 levels: trait predictors, episode predictors, and moment predictors. Discrete-time survival analyses revealed that, for all 5 emotions under study, the higher the importance of the emotion-eliciting situation and the higher the intensity of the emotion at onset, the longer the emotional experience lasts. Moreover, a reappearance, either physically or merely mentally, of the eliciting stimulus during the emotional episode extended the duration of the emotional experience as well. These findings display interesting links with predictions within N. H. Frijda's theory of emotion, with the phenomenon of reinstatement (as studied within the domain of learning psychology), and with the literature on rumination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Introduction of functional groups on polyethylene surfaces by a carbon dioxide plasma treatment

Poly(ethylene) (PE) films were treated with a carbon dioxide (CO₂) plasma to study the formation of oxygen-containing functional groups at the surface. Modified and nonmodified films were characterized by X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. During the CO₂ plasma treatment, the PE surface is etched and oxidized, yielding films with a very hydrophilic surface. The oxygen incorporation at the surface is fast and can be described by a combination of a zero-order incoraporation and a first-order etching process. Several oxygen functionalities such as carboxylic acid (approximately 14% of the oxygen persent), ketone/aldehyde (25%), and hydroxyl/epoxide (5–9%) groups were introduced at the surface by the plasma treatment. This was shown by using derivatization reactions for specific functional groups followed by XPS analysis. The wettability of the plasma-treated surface decreased when the films were stroed for prolonged periods of time in air. This aging process could not be completely reversed by immersion of the films in water. © 1995 John Wiley & Sons, Inc.     

Contamination with storage fungi of human food from Cameroon

In a mycological study, a total of 95 human food samples were investigated to evaluate the incidence of fungal contamination in Cameroon by conventional identification method and partly confirmed by DNA sequencing. The isolated fungal spp. were further studied to determine their toxigenic potentials. The investigation revealed the predominance of Aspergillus and Penicillium with 96% of samples contaminated with at least one species of these fungi, whereas the incidence of co-contamination of samples was 85%. Aspergillus flavus and Aspergillus parasiticus (Flavi section) were the most predominant species contaminating mainly maize and peanuts. In addition, P. crustosum and P. polonicum were the most common contaminants belonging to the genus Penicillium. On the other hand, A. ochraceus (Circumdati section) registered a low incidence rate of 5%, including other members of the Aspergillus group. Other members of the genera Rhizopus and Alternaria spp. were also registered in the study. A majority of fungal strains of A. ochraceus, A. parasiticus, P. crustosum and P. polonicum isolated were toxigenic, producing the mycotoxins tested for, while none was detected in cultures of A. fumigatus. The high incidence rate of fungi contamination coupled with their potentials in producing mycotoxins gives a strong indication that the samples tested may likely be contaminated with various mycotoxins. There is need for further study to assess the incidence of mycotoxins contamination in similar food samples.     

The role of wingbeat frequency and amplitude in flight power

Body-mounted accelerometers provide a new prospect for estimating power use in flying birds, as the signal varies with the two major kinematic determinants of aerodynamic power: wingbeat frequency and amplitude. Yet wingbeat frequency is sometimes used as a proxy for power output in isolation. There is, therefore, a need to understand which kinematic parameter birds vary and whether this is predicted by flight mode (e.g. accelerating, ascending/descending flight), speed or morphology. We investigate this using high-frequency acceleration data from (i) 14 species flying in the wild, (ii) two species flying in controlled conditions in a wind tunnel and (iii) a review of experimental and field studies. While wingbeat frequency and amplitude were positively correlated, R² values were generally low, supporting the idea that parameters can vary independently. Indeed, birds were more likely to modulate wingbeat amplitude for more energy-demanding flight modes, including climbing and take-off. Nonetheless, the striking variability, even within species and flight types, highlights the complexity of describing the kinematic relationships, which appear sensitive to both the biological and physical context. Notwithstanding this, acceleration metrics that incorporate both kinematic parameters should be more robust proxies for power than wingbeat frequency alone.