Harnessing the Excellent Mechanical,Barrier and Antimicrobial Properties of Zinc Oxide (ZnO) to Improve the Performance of Starch-based Bioplastic

ABSTRACT

The inherent properties of starch which are poor mechanical properties and its hydrophilicity that leads to poor long-term water absorption, fostered the incorporation of additives into starch-based bioplastic to enhance its mechanical and barrier properties. Zinc oxide (ZnO) nanoparticle as a lightweight material that is biocompatible, nontoxic, cost-effective and exhibit strong antibacterial activity can be considered as nano reinforcement of starch-based bioplastic. The present work studied the reinforcing effect of ZnO on the physical, mechanical and antibacterial properties of starch-based bioplastic. Bioplastic was prepared by melt-mixing starch and glycerol (3:1, w/w) with ZnO (1%, 2%, 3%, 4% and 5%, w/w). Bioplastic density and water contact angle increased with the increase of ZnO concentration. Bioplastic with the addition of 4% ZnO showed the lowest moisture content of 3.45%. Moreover, the decomposition temperature of bioplastic with ZnO increased slightly which indicated the higher stability. Mechanical properties evaluation showed that bioplastic with addition of ZnO had higher tensile strength than that without ZnO where 4% ZnO exhibited the highest tensile strength of 10.29 MPa with elongation of 5.69%. Cross-section microstructure after tensile test showed that ZnO was fairly dispersed in starch matrix that implied the increase of the mechanical properties of bioplastic. FTIR spectra exhibited that the intermolecular interaction in bioplastics occurred through C–H, C=O, C–O–H and O–H groups. In addition, biodegradability tests of bioplastic showed that the growth of microbes decreased in the presence of ZnO due to the nature of ZnO as an antibacterial compound. The results showed that ZnO played a key role in reinforcing the physical, mechanical and antibacterial properties of starch-based bioplastic.     

How orangutans (Pongo pygmaeus) innovate for water.

We report an observational field study that aimed to identify innovative processes in rehabilitant orangutans’ (Pongo pygmaeus) water innovations on Kaja Island, Central Kalimantan, Indonesia. We tested for the basic model of innovating (make small changes to old behavior), 4 contributors (apply old behavior to new ends, accidents, independent working out, social cross-fertilization), development, and social rank. Focal observations of Kaja rehabilitants’ behavior over 20 months yielded 18 probable innovations from among 44 water variants. We identified variants by function and behavioral grain, innovations by prevalence, and innovative processes by relations between innovations, other behaviors, and social encounters. Findings indicate innovating by small changes and some involvement of all 4 contributors; midrank orangutans were the most innovative; and rehabilitants’ adolescent age profile, orphaning, and intense sociality probably enhanced innovativeness. Important complexities include: orangutan innovating may favor certain behavioral levels and narrowly defined similarities, and it may constitute a phase-like process involving a succession of changes and contributors. Discussion focuses on links with great ape cognition and parallels with innovating in humans and other nonhuman species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Possible application of biohydrogen technologies as electricity sources in Indonesian remote areas

A prototype system for hydrogen gas production from a biological system of facultative fermentation has been applied for electricity power supply. The prototype was designed for application in remote or isolated areas in Indonesia. The fermentation system, which was designed to be as simple as possible, includes the preparation of the microbial seed, the substrate material, the vessel and other required equipment, gas capture and purification, a converter, and transportation. The model experiment in the field undergoes several modifications depending on the biomass sources in the actual location, i.e., some areas have agroforestry, sugarcane, soy sauce and palm sugar wastes. The light intensity and temperature followed the natural conditions. The results indicated that a cultivation scale of 5–25 L per substrate does not affect the result, i.e., a hydrogen production of approximately 60–70% of the total gas produced. The hydrogen gas produced was converted into electricity sources to power fans and house lamps. However, the hydrogen power is not yet sustainable due to the batch fermentation system, the biomass supply and the local electrical system, which is conventional (not a grid system). We propose to merge the electrical system in those areas, i.e., combining the source of electrical power from wind, solar, biomass, ocean current and fossil fuel-based generators. The model of the electricity pool system is important for Indonesia because, geographically, Indonesia consists of more than seventeen thousand islands, where the electricity supply remains unstable.     

Dynamic aspect-based rating system and visualization

User Modeling and User-Adapted Interaction - With an increasing number of product reviews available online, it has become impractical for potential customers to perceive all the available reviews...     

Supermolecular morphology of polypropylene filled with nanosized silica

The supermolecular morphology of injection‐molded SiO₂/polypropylene (PP) nanocomposites was investigated via thin sections analyzed under polarized light and the systematic development of an appropriate etching technique, which allowed the study of the supermolecular morphologies with light microscopy (LM) and high‐resolution field emission scanning electron microscopy (FESEM). In parallel, information regarding the dispersion, distribution state, and morphology of SiO₂ particles was investigated via transmission electron microscopy (TEM) and scanning electron microscopy (SEM) of the ion‐polished and fractured surfaces of SiO₂‐filled PP. The TEM/SEM results demonstrated an almost homogeneous dispersion and distribution of SiO₂ particle agglomerates in the PP matrix. With polarized transmitting LM, reflecting LM, and FESEM, the spherulitic structure of the nanocomposites could be visualized to obtain information on the nanoparticle influence on the crystallization and structural behavior. The size and size distribution of the spherulites analyzed with transmitting light (thin sections) and reflecting light (etched specimens) showed an excellent correlation. With increasing filler loading, the mean size of the spherulites decrease as did the degree of crystallinity. This was a clear indication that the particles acted as nucleation agents and, on the other hand, hindered the arrangement of the molecules during the crystallization. As a result, the particles were most likely located in three areas: the center of the spherulites, the areas between the highly crystalline branches, and the spherulite boundaries. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39655.     

The effectiveness of Max-half-Mchart over Max-Mchart in simultaneously monitoring process mean and variability of individual observations

Control charts are widely used in industrial environments for the simultaneous or separate monitoring of the process mean and process variability. The Max-Mchart is a multivariate Shewhart-type simultaneous control chart that is used when monitoring subgroups. While this sampling design allows the computation of the generalized variance (GV) used to calculate the process variability, a GV chart cannot be plotted for individual observations. Hence, we cannot compute the single statistic in the Max-Mchart. This study aims to overcome the aforementioned issue. To this end, first, we develop a new Max-Mchart for individual observations by utilizing the statistic in the dispersion control chart. Second, instead of the standard normal distribution, we propose a new transformation using a half-normal distribution to calculate the statistic for the process mean and process variability. Thus, the proposed chart is called the Max-Half-Mchart, whose control limit is calculated using the bootstrap approach. An evaluation based on the average run length values shows the robustness of the Max-Half-Mchart for the simultaneous monitoring of the process mean and process variability. The single statistic in the Max-Half-Mchart is more consistent with the statistic in Hotelling's T² and the dispersion chart than that of the Max-Mchart.     

Hygrothermal effects of glass fiber reinforced unsaturated polyester resin composites aged in steady and fluctuating conditions

This paper presents the water uptake and its effect on the tensile properties and the translaminar fracture toughness of glass fiber reinforced unsaturated polyester composites (GFRUPs) aged in distilled and saltwater at a temperature of 50 °C, in steady and fluctuating conditions. In both conditions, the GFRUPs aged in distilled water absorbed more water than in saltwater. The tensile strength of GFRUP tends to decrease with the immersion time in both aging media, but the decrease of tensile strength in saltwater is worse than that in distilled water. In steady condition, the translaminar fracture toughness increases after 7 days immersion and then tends to decrease beyond that immersion time. While in fluctuating condition, the translaminar fracture toughness increases until 15 days immersion and then gradually decreases up to 30 days immersion. Overall, the degradation of mechanical properties in the fluctuating condition is lower than in the steady condition.     

Nano-scale phase transformation in Ti-implanted austenitic 301 stainless steel

Phase-transformation behaviours were investigated for austenitic 301 stainless steel during implantation at room temperature with 300 keV Ti ions to fluences of 8 x 10(19) to approximately 3 x 10(21) ions m(-2) by means of transmission electron microscopy. The cross-sectional specimen was prepared using a focused ion beam. Plan observation of the implanted specimen showed that phase transformation from gamma-phase to alpha-phase was induced by implantation to a fluence of 3 x 10(20) Ti ions m(-2). The nucleation of the irradiation (implantation)-induced phase increased with the increase of the dose. The orientation relationship between the gamma matrix and the induced alpha martensitic phase was identified as (011)alpha//(111)gamma and [11-1]alpha//[10-1], close to the Kurdjumov-Sachs relationship. Cross-sectional observation after implantation to a fluence of 5 x 10(20) ions m(-2) showed that phase transformation mostly nucleated near the surface and occurred in the higher the concentration gradient of the implanted ion, i.e. a higher stress concentration takes place and this stress introduced by the implanted ions acts as a driving force for the transformation.     

Bioactivities of nostocine a produced by a freshwater cyanobacterium Nostoc spongiaeforme TISTR 8169

A freshwater cyanobacterium, Nostoc spongiaeforme TISTR 8169, synthesizes and releases a violet pigment, nostocine A, into medium. We examined the bioactivity of nostocine A to several model organisms breeding with N. spongiaeforme in the natural environment. To microalgae, nostocine A exhibited growth inhibitory activity comparable to paraquat, and the activity tended to be stronger to green algae than to cyanobacteria. Nostocine A also exhibited strong inhibitory activity to the root elongation of barnyard grass, strong antifeedant activity to cotton ballworm, and acute toxicity to mice resulting in its classification as a dangerous poison. The results suggest that nostocine A may act as a toxin or an allelochemical to breeding organisms in nature. In a laboratory culture of N. spongiaeforme, the production of nostocine A was enhanced at higher temperature, 30 degrees C, and more intense light, 30 W/m2, than the basal conditions, 25 degrees C and 10 W/m2. Cultivation of cells with H2O2 at 1 or 2 mM also enhanced the production of nostocine A, indicating that nostocine A may be synthesized and released when the cells are exposed to oxidative stress, possibly occurring at higher temperature and more intense light. LC-MS and electron spin resonance analyses revealed that nostocine A, reduced previously by NaBH4, immediately recovered to its original form upon exposure to air and the generation of superoxide radical anions occurred at this re-oxidation step. These results suggest that the adverse effects of nostocine A on various organisms may be related to the function of nostocine A in generating toxic reactive oxygen species, which occurs in the cells of target organisms.