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.     

Effect of microcrystalline cellulose on characteristics of cassava starch-based bioplastic

ABSTRACT

The vast consumption of conventional plastics has a significant effect on the environment that encourages the utilization of natural resources as the raw materials to substitute the petroleum-based plastics. Poor mechanical and moisture barrier properties of starch-based bioplastics causing the development of modified starch-based bioplastics by incorporating reinforcing material. Microcrystalline cellulose (MCC) as a filler of thermoplastic starch shows strong reinforcing ability and high surface area besides its renewability, biodegradability, and affordability compared to nanocellulose. This study aimed to investigate the effect of MCC on the physical, mechanical, and biodegradability properties of starch-based bioplastic. Bioplastic was prepared by melt-mixing starch and glycerol (3:1, w/w) with MCC (5%, 10%, 15%, and 20%, w/w). Density and water contact angle of bioplastic increased with the increase of MCC concentration. Conversely, the moisture content decreased with the increase of MCC concentration. Mechanical properties evaluation showed that bioplastic with the addition of MCC had higher tensile strength than that without MCC where 20% MCC exhibited the highest tensile strength of 16.7 MPa with elongation of 1.31% and Young’s modulus of 1.5 GPa. In addition, the decomposition temperature of bioplastic with MCC slightly increased which indicated the higher stability. Cross-section micrograph after tensile test showed that the visible inhomogeneous starch granules decreased with the increase of MCC concentration. FTIR spectra exhibited that the intermolecular interaction in bioplastics occurred through C-H, C = O, C-O-C, C-O-H, and O-H groups. In addition, biodegradability tests of bioplastic showed that the growth of microbes increased in the presence of MCC and microbes covered the bioplastic more than 60% in 21 days. The results showed that MCC performed an important role to enhance the physical, mechanical, and biodegradability 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)     

Annealing processing technique divergently affects starch crystallinity characteristic related to resistant starch content: a literature review and meta-analysis

Annealing is one of starch physical modification techniques that can increase resistant starch (RS) content. However, the effect of annealing on RS varies based on botanical sources. Starch crystal type and relative crystallinity are two important characteristics of starch. This study aimed to compare the influence of annealing on starch crystallinity and different starch crystal type (A, B and C) and investigate its effect on RS content by literature meta-analysis study. The literature review was carried out using 22 research articles and 101 data points. The result showed relative crystallinity increase from the highest changes to the lowest, respectively; C-type crystal (18.98%) followed by B (13.60%) and A-type crystal (8.17%). Meta-analysis study results showed a significant increase of RS content on starches with A-type crystal (SMD = 6.46; 95% CI: 3.22–9.70; P < 0.01) and a positive relationship between the degree of crystallinity and RS content after annealing modification.     

Synthesis,characterization, and gas separation performances of polysulfone and cellulose acetate-based mixed matrix membranes

ABSTRACT

The combination of polymeric and inorganic fillers inside mixed matrix membranes (MMMs) becomes a hot research topic due to the gas permeability-selectivity trade-off in polymeric membranes. Until recently, the problem of voids hampers the real application of MMMs, hence deep understanding on polymer-particle compatibility is required. This study focuses on the synthesis and characterization of polysulfone and cellulose acetate-based MMMs that combined with ZIF-8 and TiO₂ particles. ZIF-8 dispersed more uniform than TiO₂. The crystallinity of MMMs was higher than pure polymeric membrane. In addition, micro voids in MMMs resulted a slight decrease in CO₂/N₂ selectivity (from 15 to 12).     

High-throughput fabrication of carbonized electrospun polyacrylonitrile/poly(acrylic acid) nanofibers with additives for enhanced electrochemical sensing

Lightweight, polyacrylonitrile-derived electrodes with different additives were fabricated using high-throughput nozzle-free electrospinning. The electrospun precursor nanofibers (PNFs) containing iron oxide, gold nanoparticles, or reduced graphene oxide (rGO) were subjected to oxidative stabilization and carbonization to obtain a carbon-rich conductive nanofiber structure. Scanning electron microscopy showed that the carbon nanofibers contracted between 11 and 55% while the Fourier-transform infrared spectroscopy confirmed that the carbon nanofibers were thermally stable. Thermogravimetric and differential scanning calorimetry results revealed that the cross-linking of the chain molecules and cyclization were completed. Next, cyclic voltammetry results indicated that the electroactivity of the modified screen-printed carbon electrodes was decreased by 85% due to the presence of carbon glue. The modified device presented significant enhanced electrochemical responses with the inclusions of nanoparticles, with rGO showing a 2.13 times higher electroactive surface area, followed by iron oxide (two times) and gold nanoparticles (1.37 times) than the equivalent PNFs.     

Analysis of quality standards for industrial collaborative robots based on user-centered design framework

Industrial collaborative robots have become increasingly important in recent years due to their ability to work safely and efficiently alongside humans. As a result, there is a growing need for evaluation standards to ensure the quality of collaborative robots. However, existing studies only consider system-centered and technical aspects of collaborative robots, and there is a lack of research on user-centered quality evaluation. In this study, we identified 21 user requirements based on a user-centered design framework and confirmed the limitations of existing quality standards by reviewing the standard clauses for collaborative robots. It was found that user needs to be related to performance, safety, and even usability and enjoyment are already being expressed according to the user-centered design framework, but the quality standards for these needs only present design principles or do not consider them at all. This study provides information on the quality attributes that need to be fulfilled to satisfy user requirements and suggests the need and direction for further research on the user-centered evaluation of collaborative robots. Accordingly, the user's perception and experience of collaborative robots are expected to improve.