Comparison of Wood-Based Biocomposites with Polylactic Acid (PLA) Density Profiles by Desaturation and X-ray Spectrum Methods

Wood-plastic composites (WPCs) represent composite materials that employ shredded wood combined with a thermoplastic substance, such as polylactic acid (PLA), to establish structural cohesion within the product profile. This amalgamation of materials results in a robust structure designed to fulfill specialized roles under the influence of pressure and temperature. Given the nature of the constituent materials, the resultant product can be classified as a biocomposite. The creation of such biocomposites entails a rigorous process necessitating the fine-tuning of specific parameters and suitable technologies. The foundational materials employed in this process must be both natural and biodegradable. However, it is noteworthy that natural components like fibers exhibit anisotropic behavior, wherein their mechanical attributes are contingent on the direction of the applied force. Consequently, predicting their performance during biocomposite production proves challenging. The principal objective of this study was to conduct a comparative analysis of wood-based composites incorporating PLA thermoplastic binding agents. The intention was to discern variations in density profiles arising from distinct measurement methodologies. Two measurement methods were used for the measurement: X-ray and spectrum desaturation. Additionally, the study sought to investigate the impact of introducing PLA additives at 25% and 50% concentrations on the fabrication of WPC from wood chips. The properties of these composites were assessed by considering the inherent traits of the composite materials.

Novel and Facile Synthesis of Biodegradable Plastic Films from Cornmeal by Using the Microwave Polymerization Technique

Millions of tons of plastic are produced annually, but a major portion of plastic waste remains unrecycled. The uncycled plastic ultimately becomes a major source of solid trash and releases a variety of chemicals into our environment which can adversely affect the human health and marine life. In this study, a novel approach has been opted to synthesize a biodegradable plastic by using the microwave polymerization technique. In this novel approach, raw material (cornmeal), plasticizer (glycerin), and additive (vinegar) have been combined together to fabricate biodegradable plastic films from the microwave polymerization method. A number of rheological properties such as shear stress (Pa), shear rate (1/s), strain, and viscosity (Pa.s) of newly synthesized plastic were studied. These properties confirmed the presence of a shear thinning effect in the biodegradable plastic films on the basis of flow behavior of cornmeal. In order to check the water uptake ability and biodegradability of the cornmeal-based plastic films, water uptake and biodegradation tests were carried out. The fabricated films were neat, thin, and chewable and demonstrate promising characteristics. Therefore, these synthesized films can potentially become a suitable candidate in the packaging industry.

Lithium, Magnesium, and Zinc Centers N,N'-Chelated by an Amine-Amide Hybrid Ligand

The synthesis and structure of lithium, magnesium, and zinc complexes N,N'-chelated by a hybrid amine-amido ligand ([2-(Me₂NCH₂)C₆H₄NR]^-, abbreviated as L^NR, where R = H, SiMe₃, or Bn) are reported. The reaction of the least sterically demanding L^NH with various magnesium sources gives the hexameric imide [L^NMg]₆ (4) by the elimination of n-butane from L^NHMgⁿBu (2) or by the reaction of L^NHLi (1) with MeMgBr. [L^NH]₂Mg (3) is obtained through the addition of 0.5 equiv of ⁿBu₂Mg or Mg[N(SiMe₃)₂]₂ to L^NH₂ and with 1 equiv of ⁿBu₂Mg reacting to 2. Both L^NHMgN(SiMe₃)₂ (6) and isostructural L^NHZnN(SiMe₃)₂ (16) have been prepared using two different approaches: monodeprotonation of L^NH₂ by Zn/Mg[N(SiMe₃)₂]₂ in a 1:1 ratio or ligand substitution of 2 or L^NHZnEt (12) by 0.5 equiv of Sn[N(SiMe₃)₂]₂. The reactions of 2 or 3 with 1 provide the heterotrimetallic complex [L^NH]₄Li₂Mg (5). Benzyl- or trimethylsilyl-substituted anilines [L^N(SiMe₃)H (7) and L^N(Bn)H (8)] with 0.5 equiv of ⁿBu₂Mg allow the formation of homoleptic bis(amides) of the [L^N(R)]₂Mg type (10 and 11). Nevertheless, only the silylated secondary amine 7 is able to provide the heteroleptic n-butylmagnesium amide L^N(SiMe₃)MgⁿBu (9) upon reaction with an equimolar amount of ⁿBu₂Mg. Similarly, 12, [L^NH]₂Zn (13), L^N(R)ZnEt (17 and 18), and [L^N(R)]₂Zn [R = SiMe₃ (19) and Bn (20)] were prepared by the monodeprotonation of L^NH₂ or L^N(R)H using Et₂Zn in the corresponding stoichiometric ratio. L^NHZnI was prepared by the nucleophilic substitution of an ethyl chain in 12 by molecular iodine. A heterometallic complex, [L^NH]₄Li₂Zn (14), analogous to 5 was prepared from 12 or 13 with 1 or 2 equiv of 1, respectively.

Closing the Carbon Loop in the Circular Plastics Economy

Today, plastics are ubiquitous in everyday life, problem solvers of modern technologies, and crucial for sustainable development. Yet the surge in global demand for plastics of the growing world population has triggered a tidal wave of plastic debris in the environment. Moving from a linear to a zero-waste and carbon-neutral circular plastic economy is vital for the future of the planet. Taming the plastic waste flood requires closing the carbon loop through plastic reuse, mechanical and molecular recycling, carbon capture, and use of the greenhouse gas carbon dioxide. In the quest for eco-friendly products, plastics do not need to be reinvented but tuned for reuse and recycling. Their full potential must be exploited regarding energy, resource, and eco efficiency, waste prevention, circular economy, climate change mitigation, and lowering environmental pollution. Biodegradation holds promise for composting and bio-feedstock recovery, but it is neither the Holy Grail of circular plastics economy nor a panacea for plastic littering. As an alternative to mechanical downcycling, molecular recycling enables both closed-loop recovery of virgin plastics and open-loop valorization, producing hydrogen, fuels, refinery feeds, lubricants, chemicals, and carbonaceous materials. Closing the carbon loop does not create a Perpetuum Mobile and requires renewable energy to achieve sustainability. This article is protected by copyright. All rights reserved.

Microperforated Compostable Packaging Extends Shelf Life of Ethylene-Treated Banana Fruit

Plastic packaging preserves the quality of ethylene-treated bananas by generating a beneficial modified atmosphere (MA). However, petroleum-based plastics cause environmental pollution, due to their slow decomposition. Biodegradable packaging may help resolve this controversy, provided it shows adequate preservation efficacy. In this study, we tested the compostable biodegradable polyester packaging of ethylene-treated bananas in comparison with commercially available petroleum-based plastic alternatives. When compostable packaging was used in a non-perforated form, it caused hypoxic fermentation, manifested as impaired ripening, off-flavor, and excessive softening. Micro-perforation prevented fermentation and allowed MA buildup. Furthermore, no water condensation was observed in the biodegradable packages, due to their somewhat higher water vapor permeability compared to conventional plastics. The fruit weight loss in biodegradable packaging was higher than in polypropylene, but 3–4-fold lower than in open containers. The control of senescence spotting was the major advantage of microperforated biodegradable packaging, combined with the preservation of acceptable fruit firmness and flavor, and low crown rot incidence. Optimal biodegradable packages extended the shelf life of bananas by four days compared with open containers, and by two days compared with the best commercial plastic package tested. Microperforated biodegradable packages combined the advantage of improved sustainability with superior fruit preservation.

New Trends in Bioremediation Technologies Toward Environment-Friendly Society: A Mini-Review

Today's environmental balance has been compromised by the unreasonable and sometimes dangerous actions committed by humans to maintain their dominance over the Earth's natural resources. As a result, oceans are contaminated by the different types of plastic trash, crude oil coming from mismanagement of transporting ships spilling it in the water, and air pollution due to increasing production of greenhouse gases, such as CO₂ and CH₄ etc., into the atmosphere. The lands, agricultural fields, and groundwater are also contaminated by the infamous chemicals viz., polycyclic aromatic hydrocarbons, pyrethroids pesticides, bisphenol-A, and dioxanes. Therefore, bioremediation might function as a convenient alternative to restore a clean environment. However, at present, the majority of bioremediation reports are limited to the natural capabilities of microbial enzymes. Synthetic biology with uncompromised supervision of ethical standards could help to outsmart nature's engineering, such as the CETCH cycle for improved CO₂ fixation. Additionally, a blend of synthetic biology with machine learning algorithms could expand the possibilities of bioengineering. This review summarized current state-of-the-art knowledge of the data-assisted enzyme redesigning to actively promote new research on important enzymes to ameliorate the environment.

Core-Shell Microcapsules from Unpurified Legume Flours

Plant-based ingredients are key building blocks for future sustainable advanced materials. Functionality is typically higher for highly purified plant-based ingredients, but this is at the expense of their sustainability value. Here, a method is introduced for creating a soft functional material, with structural elements ranging from the nanometer to the millimeter scale, directly from legume flours. Globulins from soy and pea flours are extracted in their native state at acidic pH and mixed with gum arabic, resulting in liquid-liquid phase separation into a dilute phase and a viscoelastic complex coacervate. Interfacial tensions of the coacervates, determined via AFM-based probing of capillary condensation, are found to be very low (γ = 48.5 and 32.3 μN/m for, respectively, soy and pea), thus promoting the deposition of a shell of coacervate material around oil droplets. Despite the complex nature of the starting material, the dependence of interfacial tensions on salt concentrations follows a scaling law previously shown to hold for model complex coacervates. Curing of the coacervate material into a strong and purely elastic hydrogel is shown to be possible via simple heating, both in bulk and as a shell around oil droplets, thus providing proof of principle for the fabrication of precise core-shell microcapsules directly from legume flours.

Rice bran-based bioplastics: Effects of the mixing temperature on starch plastification and final properties

The agro-food industry produces huge amounts of wastes and by-products with high levels of carbohydrates and proteins, basic food groups that, properly treated, can be employed for the development of bioplastics. These high added-value products represent an alternative to traditional polymers. In this research work, rice bran was mixed with glycerol and water obtaining homogeneous blends which then are processed into bioplastics via injection moulding. The mixing temperature aids starch plastification and thus, affects the properties of the final specimens. In this way, the mechanical characterization revealed improvements for the highest temperature (110 °C) used which, at the same time, exhibited poor physical integrity during water immersion. Although the mechanical properties of the dried system obtained at 80 °C are slightly inferior to those obtained for the non-dried 110 °C system, these specimens are considered more adequate since they exhibited higher physical integrity and, consequently, better operating conditions.

Solution-Blown Poly(hydroxybutyrate) and ε-Poly-l-lysine Submicro- and Microfiber-Based Sustainable Nonwovens with Antimicrobial Activity for Single-Use Applications

Antimicrobial nonwovens for single use applications (e.g., diapers, sanitary napkins, medical gauze, etc.) are of utmost importance as the first line of defense against bacterial infections. However, the utilization of petrochemical nondegradable polymers in such nonwovens creates sustainability-related issues. Here, sustainable poly(hydroxybutyrate) (PHB) and ε-poly-l-lysine (ε-PLL) submicro- and microfiber-based antimicrobial nonwovens produced by a novel industrially scalable process, solution blowing, have been proposed. In such nonwovens, ε-PLL acts as an active material. In particular, it was found that most of ε-PLL is released within the first hour of deployment, as is desirable for the applications of interest. The submicro- and microfiber mat was tested against C. albicans and E. coli, and it was found that ε-PLL-releasing microfibers result in a significant reduction of bacterial colonies. It was also found that ε-PLL-releasing antimicrobial submicro- and microfiber nonwovens are safe for human cells in fibroblast culture. Mechanical characterization of these nonwovens revealed that, even though they are felt as soft and malleable, they possess sufficient strength, which is desirable in the end-user applications.

Investigation of Mechanical and Physical Properties of Big Sheep Horn as an Alternative Biomaterial for Structural Applications

This paper investigates the physical and mechanical properties of bighorns of Deccani breed sheep native from Karnataka, India. The exhaustive work comprises two cases. First, rehydrated (wet) and ambient (dry) conditions, and second, the horn coupons were selected for longitudinal and lateral (transverse) directions. More than seventy-two samples were subjected to a test for physical and mechanical property extraction. Further, twenty-four samples were subjected to physical property testing, which included density and moisture absorption tests. At the same time, mechanical testing included analysis of the stress state dependence with the horn keratin tested under tension, compression, and flexural loading. The mechanical properties include the elastic modulus, yield strength, ultimate strength, failure strain, compressive strength, flexural strength, flexural modulus, and hardness. The results showed anisotropy and depended highly on the presence of water content more than coupon orientation. Wet conditioned specimens had a significant loss in mechanical properties compared with dry specimens. The observed outcomes were shown at par with results for yield strength of 53.5 ± 6.5 MPa (which is better than its peers) and a maximum compressive stress of 557.7 ± 5 MPa (highest among peers). Young's modulus 6.5 ± 0.5 GPa and a density equivalent to a biopolymer of 1.2 g/cc are expected to be the lightest among its peers; flexural strength 168.75 MPa, with lowest failure strain percentage of 6.5 ± 0.5 and Rockwell hardness value of 60 HRB, seem best in the class of this category. Simulation study identified a suitable application area based on impact and fatigue analysis. Overall, the exhaustive experimental work provided many opportunities to use this new material in various diversified applications in the future.

Making Biodegradable Seedling Pots from Textile and Paper Waste-Part B: Development and Evaluation of Seedling Pots

This study evaluates the efficacy of using textile waste blended with paper waste to form biodegradable seedling pots. A bio-composite blend of cotton (20% cotton, 40% newspaper, and 40% corrugated cardboard) and polycotton (20% polycotton, 40% newspaper, and 40% corrugated cardboard) with an optimum strength was formed into seedling pots. The appreciated seedling pots (untreated blends of cotton and polycotton) were compared with the commercial pots (cardboard seed starter pot and Jiffy pot) in terms of mechanical properties (tensile strength and compressive strength), biodegradability (soil burial test and anaerobic digestion), and seed germination. The untreated blends of cotton and polycotton pots demonstrated a comparable optimum strength, while the Jiffy pot and cardboard seed starter pot obtained the least tensile and compressive strengths, respectively. The anaerobic biodegradability assay suggests that the cotton blend pot, polycotton blend pot, and cardboard seed starter pot can degrade anaerobically because of high biogas and methane generation potential. A 100% seed germination was observed from the four seedling pots tested. Thus, the results demonstrate the efficacy of utilizing textile waste and paper waste to develop seedling pots with desirable strength and biodegradability compared to the commercial pots.

Amine-Catalyzed Chain Polymerization of Ethyl Glyoxylate from Alcohol and Thiol Initiators

Polyacetals have significant potential as degradable polymers, but aldehyde polymerizations are generally difficult to control. Here we show that polymerization of ethyl glyoxylate can be initiated from alcohols or thiols by activation with triethylamine to afford poly(ethyl glyoxylate) with controllable molecular weights and relatively low dispersities (Đ = 1.3-1.4), as evidenced by MALDI-TOF mass spectrometry. Stabilization against depolymerization by chain-capping with benzyl chloroformate was found to proceed without side reactions observed from chain-capping with tolyl isocyanate. The use of the stronger base DBU leads to competing side reactions that limit polymer molecular weight.

A Review on Natural Fiber Bio-Composites, Surface Modifications and Applications

Increased environmental concerns and global warming have diverted focus from eco-friendly bio-composites. Naturals fibers are abundant and have low harvesting costs with adequate mechanical properties. Hazards of synthetic fibers, recycling issues, and toxic byproducts are the main driving factors in the research and development of bio-composites. Bio-composites are degradable, renewable, non-abrasive, and non-toxic, with comparable properties to those of synthetic fiber composites and used in many applications in various fields. A detailed analysis is carried out in this review paper to discuss developments in bio-composites. The review covers structure, morphology, and modifications of fiber, mechanical properties, degradable matrix materials, applications, and limitations of bio-composites. Some of the key sectors employing bio-composites are the construction, automobile, and packaging industries. Furthermore, bio-composites are used in the field of medicine and cosmetics.

Investigating the adsorption of anisotropic diblock copolymer worms onto planar silica and nanocellulose surfaces using a quartz crystal microbalance

We report physical adsorption of highly anisotropic copolymer worms with either anionic or cationic charge onto planar silica, cellulose nanocrystal or cellulose nanofibril surfaces using a quartz crystal microbalance with dissipation monitoring.

Insight Into the Prospects for the Improvement of Seed Starch in Legume-A Review

In addition to proteins and/or oils, mature seeds of most legume crops contain important carbohydrate components, including starches and sugars. Starch is also an essential nutritional component of human and animal diets and has various food and non-food industrial applications. Starch is a primary insoluble polymeric carbohydrate produced by higher plants and consists of amylose and amylopectin as a major fraction. Legume seeds are an affordable source of not only protein but also the starch, which has an advantage of being resistant starch compared with cereal, root, and tuber starch. For these reasons, legume seeds form a good source of resistant starch-rich healthy food with a high protein content and can be utilized in various food applications. The genetics and molecular details of starch and other carbohydrate components are well studied in cereal crops but have received little attention in legumes. In order to improve legume starch content, quality, and quantity, it is necessary to understand the genetic and molecular factors regulating carbohydrate metabolism in legume crops. In this review, we assessed the current literature reporting the genetic and molecular basis of legume carbohydrate components, primarily focused on seed starch content. We provided an overview of starch biosynthesis in the heterotrophic organs, the chemical composition of major consumable legumes, the factors influencing starch digestibility, and advances in the genetic, transcriptomic, and metabolomic studies in important legume crops. Further, we discussed breeding and biotechnological approaches for the improvement of the starch composition in major legume crops. The information reviewed in this study will be helpful in facilitating the food and non-food applications of legume starch and provide economic benefits to farmers and industries.

Expression of a functional recombinant vascular endothelial growth factor 165 (VEGF165) in Arabidopsis thaliana

Objective

Targeting the protein of interest to a particular tissue to achieve high-level expression is an important strategy to increase expression efficiency. The use of the plant seed oil body as a bioreactor can not only increase the amount of target protein, but also reduce the cost of downstream processing.

Methods

VEGF165 was expressed in Arabidopsis thaliana seeds via oilbody fusion technology. The pKO-VEGF165 vector was construted and transformed into A. thaliana seeds. T3 transgenic seeds was detected by SDS-PAGE and western blot methods. The cell activity was tested by MTT methods.

Result

The phaseolin promoter was used to drive seed-specific expression of the VEGF165 gene in transgenic A. thaliana. The coding region of VEGF165 was fused to the Arabidopsis oleosin sequence to target the protein to the oil bodies in the seeds of transgenic plants. The T-DNA region of recombinant plasmid pKO-VEGF165 was shifted to A. thaliana seeds via the floral-dip method. Protein was analyzed by electrophoresis and protein hybridization analyses. Finally, MTT assays showed that the oleosin-VEGF165 fusion protein played a part in the proliferation of HUVEC cells in vitro.

Conclusion

Oleosin-VEGF165 was successfully expressed and it had stimulated HUVEC cell proliferation activity.

Acetate-Inducing Metabolic States Enhance Polyhydroxyalkanoate Production in Marine Purple Non-sulfur Bacteria Under Aerobic Conditions

Polyhydroxyalkanoates (PHAs) are a family of biopolyesters that a variety of microorganisms accumulate as carbon and energy storage molecules under starvation conditions in the presence of excess carbon. Anoxygenic photosynthetic bacteria exhibit a variety of growth styles and high PHA production activity. Here, we characterized PHA production by four marine purple non-sulfur bacteria strains (Rhodovulum sulfidophilum, Rhodovulum euryhalinum, Rhodovulum imhoffii, and Rhodovulum visakhapatnamense) under different growth conditions. Unlike the well-studied PHA-producing bacteria, nutrient limitation is not appropriate for PHA production in marine purple non-sulfur bacteria. We found that marine purple non-sulfur bacteria did not accumulate PHA under aerobic conditions in the presence of malate and pyruvate. Interestingly, PHA accumulation was observed upon the addition of acetate under aerobic conditions but was not observed upon the addition of reductants, suggesting that an acetate-dependent pathway is involved in PHA accumulation. Gene expression analysis revealed that the expression of isocitrate dehydrogenase in the tricarboxylic acid (TCA) cycle decreased under aerobic conditions and increased with the addition of acetate, indicating that TCA cycle activity is involved in PHA production under aerobic conditions. We also found that expression of PdhR_rs, which belongs to the GntR family of transcription regulators, in Rhodovulum sulfidophilum was upregulated upon the addition of acetate. Taken together, the results show that the changes in the metabolic state upon the addition of acetate, possibly regulated by PdhR, are important for PHA production under aerobic conditions in marine purple non-sulfur bacteria.

Use of a convolutional neural network for the classification of microbeads in urban wastewater

Scientists are on the lookout for a practical model that can serve as a standard for sorting out, identifying, and characterizing microplastics which are common occurrences in water sources and wastewaters. The microbeads (MBs) used in cosmetics and discharged into the sewer systems after use cause substantial microplastics pollution in the receiving waters. Today, the use of plastic microbeads in cosmetics is banned. The existing use cases are to be discontinued within a few years. Yet, there are no restrictions regarding the use of microbeads in a number of industries, cleaning products, pharmaceuticals and medical practices. In this context, the determination and classification of MBs which had so far been discharged to water sources and which continue to be discharged, represent crucial problems. In this work, we examined a new approach for the classification of MBs based on microscopic images. For classification purposes, Convolutional Neural Network (CNN) -a Deep Learning algorithm- was employed, whereas GoogLeNet architecture served as the model. The network is built from scratch, and trained then after tested on a total of 42928 images containing MBs in 5 distinct cleansers. The study performed with the CNN which achieved a classification performance of 89% for MBs in wastewater.

Zein film functionalized with gold nanoparticles and the factors affecting its mechanical properties

In this article, we report a simple method to synthesize biodegradable zein films functionalized with gold nanoparticles (AuNPs) with significantly improved mechanical properties, as an environmentally benign substitute to biologically hazardous polymers. Zein-coated AuNPs were synthesized using the zein protein as a reducing agent and characterized with IR, UV, CD, ζ-potential, and TEM measurements. The zein protein interaction with the negatively charged surface of AuNPs provides excellent strength to the zein thin film. For the first time, FT-IR spectral studies suggested the strong interaction between AuNPs and zein protein, which was further supported by the higher binding constant (K_b) value. The films were characterized for mechanical properties with spectroscopic and physical experimental investigations. The surface morphology of AuNP-doped zein film was explored by AFM and SEM, which suggested that the AuNPs prevent the buckling of zein film and increase the strength as well as flexibility of the film.

A green chemical approach to substitute biologically hazardous polymer.

Melt Viscoelastic Assessment of Poly(Lactic Acid) Composting: Influence of UV Ageing

This study is devoted to the degradation pathway (bio, photo degradation and photo/bio) of Poly(Lactic acid) PLA polymers by means of melt viscoelasticity. A comparison was made between three PLA polymers with different microstructures (L, D stereoisomers). Biodegradability was determined during composting by burying the polymer films in compost at 58 °C. Melt viscoelasticity was used to assess the molecular evolution of the materials during the composting process. Viscoelastic data were plotted in the complex plane. We used this methodology to check the kinetics of the molecular weight decrease during the initial stages of the degradation, through the evolution of Newtonian viscosity. After a few days in compost, the Newtonian viscosity decreased sharply, meaning that macromolecular chain scissions began at the beginning of the experiments. However, a double molar mass distribution was also observed on Cole–Cole plots, indicating that there is also a chain recombination mechanism competing with the chain scission mechanism. PLA hydrolysis was observed by infra-red spectroscopy, where acid characteristic peaks appeared and became more intense during experiments, confirming hydrolytic activity during the first step of biodegradation. During UV ageing, polymer materials undergo a deep molecular evolution. After photo-degradation, lower viscosities were measured during biodegradation, but no significant differences in composting were found.

Mitigation measures to avert the impacts of plastics and microplastics in the marine environment (a review)

The increasing demand for and reliance on plastics as an everyday item, and rapid rise in their production and subsequent indiscriminate disposal, rise in human population and industrial growth, have made the material an important environmental concern and focus of interest of many research. Historically, plastic production has increased tremendously to over 250 million tonnes by 2009 with an annual increased rate of 9%. In 2015, the global consumption of plastic materials was reported to be > 300 million tonnes and is expected to surge exponentially. Because plastic polymers are ubiquitous, highly resistant to degradation, the influx of these persistent, complex materials is a risk to human and environmental health. Because microplastics are principally generated from the weathering or breakdown of larger plastics (macroplastics), it is noteworthy and expedient to discuss in detail, expatiate, and tackle this main source. Macro- and microplastic pollution has been reported on a global scale from the poles to the equator. The major problem of concern is that they strangulate and are ingested by a number of aquatic biota especially the filter feeders, such as molluscs, mussels, oysters, from where it enters the food chain and consequently could lead to physical and toxicological effects on aquatic organisms and human being as final consumers. To this end, in order to minimise the negative impacts posed by plastic pollution (macro- and microplastics), a plethora of strategies have been developed at various levels to reduce and manage the plastic wastes. The objective of this paper is to review some published literature on management measures of plastic wastes to curb occurrence and incidents of large- and microplastics pollution in the marine environments.

Ring-Opening Polymerization Reactions of ε-Caprolactone and Lactides Initiated by (Benzimidazolylmethyl)amino Magnesium(II) Alkoxides

Reactions of (benzimidazolylmethyl)amine ligands N-((1H-benzo[s]imidazol-2-yl)methyl)-2,6-dimethylaniline (L1), N-((1H-benzo[d]imidazol-2-yl)methyl)-2,6-diisopropylaniline (L2), and N-((1H-benzo[d]imidazol-2-yl)methyl)-2,4,6-trimethylaniline (L3) with Mg(nBu)2 in the presence of either benzyl alcohol (BnOH) or tert-butyl alcohol (t-BuOH) afforded the respective MgII alkoxides [Mg(L1)(OBn)]2 (1), [(Mg(L2)(OBn)]2 (2), [Mg(L3)(OBn)]2 (3), [Mg(L2)(t-BuO)]2 (4). Complexes 1–4 formed efficient catalysts for the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL), d,l-lactide (d,l-LA) and l-lactide (l-LA) at 110°C. The catalytic activities of these complexes in the ROP reactions were influenced by the steric effect of the ligands. Kinetic studies showed pseudo-first-order dependency on monomer. Polycaprolactone and polylactides of moderate weight-average molecular weights of 15285 and 5200 g mol−1 and fairly narrow polydispersity indexes from 1.24 to 1.58 were produced.

Graphene Oxide Filled Lignin/Starch Polymer Bionanocomposite: Structural, Physical, and Mechanical Studies

In this study, graphene oxide (GO) was investigated as a potential nanoreinforcing agent in starch/lignin (ST/L) biopolymer matrix. Bionanocomposite films based on ST/L blend matrix and GO were prepared by solution-casting technique of the corresponding film-forming solution. The structures, morphologies, and properties of bionanocomposite films were characterized by Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), ultraviolet-visible (UV-vis), SEM, and tensile tests. The experimental results showed that content of GO have a significant influence on the mechanical properties of the produced films. The results revealed that the interfacial interaction formed in the bionanocomposite films improved the compatibility between GO fillers and ST/L matrix. The addition of GO also reduced moisture uptake (Mu) and water vapor permeability of ST/L blend film. In addition, TGA showed that the thermal stability of bionanocomposite films was better than that of neat starch film. These findings confirmed the effectiveness of the proposed approach to produce biodegradable films with enhanced properties, which may be used in packaging applications.

Class I Polyhydroxyalkanoate Synthase from the Purple Photosynthetic Bacterium Rhodovulum sulfidophilum Predominantly Exists as a Functional Dimer in the Absence of a Substrate

Polyhydroxyalkanoates (PHAs) are a family of biopolyesters that accumulate as carbon and energy storage compounds in a variety of micro-organisms. The marine purple photosynthetic bacterium Rhodovulum sulfidophilum is capable of synthesizing PHA. In this study, we cloned a gene encoding a class I PHA synthase from R. sulfidophilum (phaC_Rs ) and synthesized PhaC_Rs using a cell-free protein expression system. The specific activity of PhaC_Rs increased linearly as the (R)-3-hydroxybutyryl-coenzyme A (3HB-CoA) concentration increased and never reached a plateau, even at 3.75 mM 3HB-CoA, suggesting that PhaC_Rs was not saturated because of low substrate affinity. Size exclusion chromatography and native polyacrylamide gel electrophoresis analyses revealed that PhaC_Rs exists predominantly as an active dimer even in the absence of 3HB-CoA, unlike previously characterized PhaCs. The linear relationship between the PhaC_Rs activity and 3HB-CoA concentrations could result from a low substrate affinity as well as the absence of a rate-limiting step during PHA polymerization because of the existence of predominantly active dimers.

OsMPH1 regulates plant height and improves grain yield in rice

Plant height is a major trait affecting yield potential in rice. Using a large-scale hybrid transcription factor approach, we identified the novel MYB-like transcription factor OsMPH1 (MYB-like gene of Plant Height 1), which is involved in the regulation of plant height in rice. Overexpression of OsMPH1 leads to increases of plant height and grain yield in rice, while knockdown of OsMPH1 leads to the opposite phenotypes. Microscopy of longitudinal stem sections indicated that a change in internode cell length resulted in the change in plant height. RNA sequencing (RNA-seq) analysis of transgenic rice lines showed that multiple genes related to cell elongation and cell wall synthesis, which are associated with plant height and yield phenotypes, exhibited an altered expression profile. These results imply that OsMPH1 might be involved in specific recognition and signal transduction processes related to plant height and yield formation, providing further insights into the mechanisms underlying the regulation of plant height and providing a candidate gene for the efficient improvement of rice yield.

Reinforcement of natural rubber latex using lignocellulosic nanofibers isolated from spinifex grass

Reinforcement of natural rubber (NR) using nanofillers often results in an enhancement of the tensile strength, but at the expense of elongation at break and toughness. In this study, with the objective of strengthening NR without compromising its compliance, we investigate the reinforcement efficiency of a series of cellulose nanofibers (CNF) with variations in residual hemicellulose, lignin and therefore surface chemistry. Different types of high aspect ratio CNF isolated from Triodia pungens (T. pungens), an Australian arid grass commonly known as spinifex, were added at 0.1-2 wt% loadings into a pre-vulcanized NR latex. CNF/NR nanocomposites then were benchmarked against NR nanocomposites incorporating a well-known wood-derived CNF. It was found that the presence of residual lignin and hemicellulose, and the pretreatment with a deep eutectic solvent, a mixture of choline chloride and urea (CCU), could increase the compatibility of CNF with the NR matrix, while still enabling stability and handling of the colloidal latex mixture. Incorporation of 0.5 and 0.1 wt% of the sodium hydroxide treated CNF and choline chloride/urea treated CNF into the NR latex showed respectively 11 and 17% enhancement in tensile stress, and importantly without compromising viscoelastic properties; while addition of 0.1 wt% wood-derived CNF resulted in 18% decrease in both tensile stress and strain coupled with more pronounced latex stiffening.

Development and Characterization of Polymer Eco-Composites Based on Natural Rubber Reinforced with Natural Fibers

Natural rubber composites filled with short natural fibers (flax and sawdust) were prepared by blending procedure and the elastomer cross-linking was carried out using benzoyl peroxide. The microbial degradation of composites was carried out by incubating with Aspergillus niger recognized for the ability to grow and degrade a broad range of substrates. The extent of biodegradation was evaluated by weight loss and cross-linking degree study of composites after 2 months incubation in pure shake culture conditions. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) have proved to be precious and valuable instruments for morphological as well as structural characterization of the composites before and after incubation with Aspergillus niger.

Uncertainty in the Life Cycle Greenhouse Gas Emissions from U.S. Production of Three Biobased Polymer Families

Interest in biobased products has been motivated, in part, by the claim that these products have lower life cycle greenhouse gas (GHG) emissions than their fossil counterparts. This study investigates GHG emissions from U.S. production of three important biobased polymer families: polylactic acid (PLA), polyhydroxybutyrate (PHB) and bioethylene-based plastics. The model incorporates uncertainty into the life cycle emission estimates using Monte Carlo simulation. Results present a range of scenarios for feedstock choice (corn or switchgrass), treatment of coproducts, data sources, end of life assumptions, and displaced fossil polymer. Switchgrass pathways generally have lower emissions than corn pathways, and can even generate negative cradle-to-gate emissions if unfermented residues are used to coproduce energy. PHB (from either feedstock) is unlikely to have lower emissions than fossil polymers once end of life emissions are included. PLA generally has the lowest emissions when compared to high emission fossil polymers, such as polystyrene (mean GHG savings up to 1.4 kg CO2e/kg corn PLA and 2.9 kg CO2e/kg switchgrass PLA). In contrast, bioethylene is likely to achieve the greater emission reduction for ethylene intensive polymers, like polyethylene (mean GHG savings up to 0.60 kg CO2e/kg corn polyethylene and 3.4 kg CO2e/kg switchgrass polyethylene).

Involvement of ethylene-responsive microRNAs and their targets in increased latex yield in the rubber tree in response to ethylene treatment

The rubber tree is an economically important plant that produces natural rubber for various industrial uses. The application of ethylene contributes to increased latex production in rubber trees; however, the molecular biology behind the effects of ethylene on latex yield remains to be elucidated. Recently, the intersection between microRNA (miRNA) regulation and phytohormone responses has been revealed. Insight into the regulation of miRNAs and their target genes should help to determine the functional importance of miRNAs as well as the role of miRNAs in signaling under ethylene stimulation in the rubber tree. In this study, hbr-miR159 and hbr-miR166 were down-regulated in bark under ethylene treatment. The ethylene also down-regulated ATHB15-like (Class III Homeodomain Leucine Zipper, HD-ZIP III) which have been extensively implicated in the regulation of primary and secondary vascular tissue pattern formation. The strong negative-regulation of ARF6/ARF8 caused by hbr-miR167 involved in an attenuation of vascular development and may gradually lead to bark dryness syndrome in the long term ethylene treatment. The negative correlation of hbr-miR172 and its target REF3 in the inner soft bark under ethylene treatment results in dramatic increases in latex yield in the ethylene-sensitive clone of the rubber tree. The overall results suggested that the differential expression of HD-ZIP III, miR167/ARF6, ARF8, and miR172/REF3 and related genes may play possible roles in the response to ethylene treatment, resulting in longer latex flow and increased latex yield.