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The main goal of this research is to utilize sustainable and eco-friendly basalt materials for the fabrication of bio-based thermoplastic composites. This will help to keep up with ecologically balanced factors. There have been several studies on natural fiber reinforced with different polymer matrices during the past 10 years. As a result, the academics and experts expressed concern about the environmental imbalance. By keeping these points, an attempt was made to fabricate basalt fillers reinforced polylactic acid composites with the maximum weight ratio (30 wt %), and the tribological study is conducted for the fabricated composites. In this study, the Taguchi and analysis of variance (ANOVA) approaches have been used to analyze the coefficient of friction (COF) and specific wear rate (SWR) of polylactic acid composite reinforced with constant 30 wt% basalt fillers. The morphology, particle size, and elemental composition of the basalt fillers are examined using scanning electron microscopy, a particle size distribution analyzer, and energy-dispersive X-ray analysis, respectively. The tribology tests are conducted with Pin-on-Disk Tribometer following the ASTM G99 standard, following the L18 orthogonal array design, which was developed using the statistical program MINITAB-19. The selected parameters for the analysis are basalt (wt %), load (N), speed (rpm), and distance (m) under dry conditions. For PLA samples, the optimum parameters in response to COF is found to be 0 wt% basalt, 3 N load, 100 rpm speed, and 100 m distance; for the SWR output, the optimum parameters are 30 wt% basalt, 6 N load, 100 rpm speed, and 150 m distance. The consistent observation is that adding basalt fillers has not significantly reduced COF but has contributed more to SWR reduction with PLA composite. The best COF value for PLA samples is obtained with low sliding distance. The typical observation across all COF graphs is that the COF value first seems to be lower due to a smoothened polymer surface, rises throughout an experiment, and then stabilizes with very little variance. Regardless of the processing parameters, the depth of wear steadily increases with increasing load as observed in 2D depth profiles. The neat PLA polymer morphology that gives the illusion of deep grooves and many tracks dispersed over a single worn surface shows how the maximum parameter influence is more obvious on the surface of the sample. Overall, the results suggest that thermoplastic composites are feasible for the manufacturing of paper mill rollers. [ABSTRACT FROM AUTHOR]

Printed circuit board application shows how banana fiber-reinforced polymer composites can be used to make printed circuit boards (PCBs). The study looks into how well banana fiber works as a reinforcement material for polymer composites and how it could be used to make PCBs. The banana fabric is treated with alkali to improve its mechanical properties. It is then mixed with epoxy resin to make a composite material. The composite's mechanical, thermal, and electrical properties were characterized. The results showed that the banana fiber-reinforced composites exhibited comparable mechanical properties and thermal stability to the conventional substrates. The dielectric constant and loss tangent of the composite were also within the acceptable range for PCB applications. The paper concludes that banana fabric-incorporated polymer composites have great potential for PCB fabrication, especially in applications where environmental sustainability is a priority. The use of natural fibers like banana can reduce the environmental impact of PCB fabrication while also providing good mechanical and electrical properties. This study opens up new opportunities for the use of natural fiber-reinforced composites in the electronics industry. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANNs) have gained prominence as a reliable model for clustering, grouping, and analysis in various domains. In recent times, machine learning (ML) models such as ANNs have proved to be on par with traditional regression and statistical models in terms of performance and usability. This study focuses on the fabrication of multicomponents-reinforced composites (Boron carbide (B4C) and Graphite (Gr)) using the stir casting technique. The addition of Magnesium to the melt enhances the wettability of B4C and Gr particles within the matrix. The microstructure and mechanical properties of the resulting Al-Mg-metal matrix composites (MMCs) are analyzed. Scanning electron micrographs reveal that B4C and Gr particles were uniformly dispersed in the matrix. X-Ray diffraction analysis confirmed the dispersion of the strengthening. The mechanical properties, including hardness, tensile, compressive, and impact strength, increased with the increase in B4C and Gr wt.%. As the percentage of B4C and Gr reinforcement wt.% increased, the load on the matrix reduced and its load-bearing capacity improved. The strain field generation rate also increased with an increase in B4C and Gr in the matrix, resulting in enhanced mechanical properties. The ANN analysis further confirmed that B4C was the more significant contributor to the mechanical properties of the composites. [ABSTRACT FROM AUTHOR]

Aluminium MMCs are among the many metal composites and are regarded as progressive engineering materials in numerous industries because of their advantages compared to standard aluminium alloy. Among the reinforcements in MMCs, ceramic particles are preferred for their superior wear resistance, temperature resistance, and adhesion to their matrix, making them a popular choice. This research work has been carried out to synthesise ceramic particle-reinforced aluminium metal matrix composites and to evaluate their tribological properties at different temperatures (50–300℃). Al2618 alloy was selected as the matrix, and boron carbide (B4C) and graphite (Gr) were selected as reinforcements. Hybrid composites are prepared through stir casting by varying the wt.% of B4C and Gr reinforcement particles with a ratio of 3:2. Microstructural observation shows the uniform distribution of B4C and Gr particles throughout the matrix without any agglomeration, and it also exhibits excellent scanning electron microscope (SEM). X-ray diffraction analysis (XRD) was performed to verify the presence of different constituents in the developed material. Samples S4 (Al 2618 + 12 wt.% B4C—8 wt.% Gr) and S5 (Al 2618 + 15 wt.% B4C—10 wt.% Gr) exhibit enhanced wear resistance (16.45%) due to the incorporation of a higher quantity of Gr solid lubricants alongside B4C within the temperature range of 50 to 300℃. The thickness and stability of the glazed layer exhibited adequate resistance to wear. [ABSTRACT FROM AUTHOR]

This review article addresses the potential for biopolymer-based composites made from agricultural waste biomass to replace conventional materials in a sustainable and responsible manner. The composition and manufacturing method of biopolymer-based composites are described in the article, along with some of their distinctive qualities and benefits, such as their low cost, renewable nature, and biodegradability. The article also shows a number of real-world uses for these composites, including packaging, construction, vehicle parts, biofuels, soil amendments, and medical uses. Overall, the article highlights the potential of biopolymer-based composites made from agricultural waste biomass for lowering waste generation, decreasing dependency on non-renewable resources, and boosting sustainability in a variety of industries. [ABSTRACT FROM AUTHOR]

Structural uses in the vehicle, aerospace, and sporting goods industries are being supplanted by hybrid composites that utilized natural fibers as reinforcements. The main focus of this work is to fabricate and characterize the ramie, hemp, and kevlar fabric reinforced hybrid vinyl ester composites. The composite laminates were fabricated via economically feasible and flexible hand lay‐up technique. Overall six composites were prepared by varying the stacking sequence, including both hybrid and non‐hybrid composites. The prepared composites were subjected to physical analysis (density, void fraction), mechanical tests (tensile, flexural, interlaminar shear, and impact test), morphological analysis (scanning electron microscopy), and water absorption test. The hybrid composites exhibited lesser void percentage than the non‐hybrid composites. The mechanical properties were maximum for kevlar fabric skinned with core natural fabric reinforced composites (L‐5, L‐6) due to hybridization of highly strengthened kevlar fabrics. Moreover, the number fabric layers reinforced to achieve the standard thickness also affected the mechanical properties. All composite morphologies exhibited the same failure characteristics, including transverse interlaminar shear cracking, microbuckling, and fiber rip. The texture of the Kevlar yarns is uniform, but the texture of the natural fabric yarns is relatively less uniform. In comparison to the salt water medium, the percentage of water absorbed by composites in normal and distilled water was greater. This is due to the presence and accumulation of salt particles on the surface of the materials, which inhibits the action of water molecules, resulting in a drop in the proportion. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Artificial neural networks (ANNs) have recently gained popularity as useful models for grouping, clustering, and analysis in a wide range of fields. An ANN is a kind of machine learning (ML) model that has become competitive with traditional regression and statistical models in terms of useability. Lightweight composite materials have been acknowledged to be the suitable materials, and they have been widely implemented in various industrial settings due to their adaptability. In this research exploration, hybrid composite materials using Al2618 reinforced with B4C and Gr were prepared and then evaluated for hardness and wear behavior. Reinforced alloys have a higher (approximately 36%) amount of ceramic phases than unreinforced metals. With each B4C and Gr increase, the wear resistance continued to improve. It was found that microscopic structures and an appearance of homogenous particle distribution were observed with an electron microscope, and they revealed a B4C and Gr mixed insulation surface formed as a mechanically mixed layer, and this served as an effective insulation surface that protected the test sample surface from the steel disc. The ANN and Taguchi results confirm that load contributed more to the wear rate of the composites. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This review article discusses the environmental and economic effects of recycling, as well as sustainable thermoplastic polymer recycling technologies. Several researchers have utilized recycled thermoplastics as matrices in the production of a variety of natural and synthetic‐based composites, which is also the focus of this study. All of the industries (food and packaging, construction and building, transportation, and indoor usage) where recycled thermoplastics have a large market share (food and packaging, construction and building, transportation, and indoor usage) are covered in this review. The desirable properties of thermoplastic polymers, such as corrosion resistance, low density, and user‐friendliness, have caused plastic production to surpass aluminum and other metals in use over the past 60 years. Furthermore, recycling is one of the most important measures available to mitigate these effects and is one of the most dynamic segments of the plastics industry at present. Increased landfilling and incineration of plastics have a negative impact on the ecosystem, and the continued increase in the production of virgin fossil plastic also has a negative impact on the environment. Consequently, this continuous production could lead to the depletion of fossil fuel resources, an increase in environmental emissions during processing, and eventual incineration. Increasing numbers of nations are adopting the circular economy concept in an effort to avoid all of these problems. This concept emphasizes the reuse of products and resources, as well as the recycling of materials according to the waste hierarchy, rather than their cremation or disposal in the environment. [ABSTRACT FROM AUTHOR]

3D printing is a constantly expanding technology that represents one of the most exciting and disruptive production possibilities available today. This technology has gained global recognition and garnered considerable attention in recent years. However, technological breakthroughs, particularly in the field of material science, continue to be the focus of research, particularly in terms of future advancements. The 3D printing techniques are employed for the manufacturing of advanced multifunctional polymer composites due to their mass customization, freedom of design, capability to print complex 3D structures, and rapid prototyping. The advantages of 3D printing with multipurpose materials enable solutions in challenging locations such as outer space and extreme weather conditions where human involvement is not possible. Each year, numerous research papers are published on the subject of imbuing composites with various capabilities such as magnetic, sensing, thermal, embedded circuitry, self-healing, and conductive qualities by the use of innovative materials and printing technologies. This review article discusses the various 3D printing techniques used in the manufacture of polymer composites, the various types of reinforced polymer composites (fibers, nanomaterials, and particles reinforcements), the characterization of 3D printed parts, and their applications in a various industries. Additionally, this review discussed the limitations of 3D printing processes, which may assist future researchers in increasing the utility of their works and overcoming the shortcomings of previous works. Additionally, this paper discusses processing difficulties, anisotropic behavior, stimuli-responsive characteristics (shape memory and self-healing materials), CAD constraints, layer-by-layer appearance, and void formation in printed composites. Eventually, the promise of maturing technology is discussed, along with recommendations for research activities that are desperately required to realize the immense potential of operational 3D printing. [ABSTRACT FROM AUTHOR]

In this research work, the natural fiber reinforced hybrid epoxy composites were fabricated using the hand lay‐up method. The flax and kevlar are used as a reinforcement and epoxy as a binding material. This study aims to analyze the influence of stacking sequence and hybridization on the mechanical, water absorption, and morphological properties of polymer composites. The results reveal that the neat kevlar reinforced composite achieved a maximum tensile strength, modulus, and impact strength of 189.94 MPa, 2345.35 MPa and 37.16 kJ/m2 respectively with less water absorption behavior. Whereas, the hybrid composite with kevlar as an outer layers and flax as core layers was exhibited a maximum flexural strength, modulus, and inter laminar shear strength of 360.76, 37124.2, and 213.51 MPa, respectively. The water absorption percentage was more in neat natural flax reinforced epoxy composite due to its more hydrophilic nature. The scanning electron microscope analysis reveals the proper bonding and adhesion of both kevlar and flax fabrics with the epoxy matrix. [ABSTRACT FROM AUTHOR]

A single crystal of l-phenylalanine l-phenylalanininum malonate (LPPMA) was synthesized by slow evaporation and was subjected to nonlinear optical examination and physio-chemical characterization. Studies on single X-ray diffraction confirm the arrangement of monoclinic space group P21 which is a vital criterion for the NLO phenomenon. The assessment of functional groups and diverse vibration modes responsible for the characteristics of the material was performed with an FTIR analysis. The UV-visible spectral examination found the wavelength of UV-cutoff at 233 nm and various optical parameters were evaluated. The mechanical strength and different criteria associated with it were assessed. The electric field response of the material was examined in terms of the dielectric constant, dielectric loss, ac conductivity and activation energy. The spectra of emission were detailed. The efficacy of second harmonic generation was studied. The parameters of nonlinearity were investigated to analyse the third-order acentric optical response in the LPPMA by Z-scan procedure. [ABSTRACT FROM AUTHOR]

The continuous demands for reducing environmental impact and energy consumption are the major driving factors for the development of natural fiber (NF)‐reinforced composites (NFRCs). The huge demand for sustainable materials in industries leads to the usage of NFs in product developments. These NFs are more attractive due to their lightweight, cost‐effectiveness, ease of availability, and environmentally friendly aspects. Green composites are the best alternatives in place of petroleum‐based composites which meet the current industrial requirements. In recent years, researchers are more focused on the development of NF composites as a potential candidate in real‐life applications due to economic advantages. This review gives a brief overview of NFs introduction, types, economic aspects, and the recent developments in NFRCs with an analysis of mechanical, thermal, and dielectric properties. Moreover, the water absorption behavior, applications, and challenges in using NFs are also studied in this review. Additionally, this review will motivate the researchers for further developments and exist as foundation literature for upcoming researchers. [ABSTRACT FROM AUTHOR]

The main challenging things in railway vehicles are to reduce the consumption of energy for transportation and to decrease the emission of harmful gasses by limiting the consumption of fuel sources. These drawbacks can be overcome by lightweight structures designed for the vehicle bodies and frameworks. The composite materials with fiber reinforcements are the preferred choice for manufacturing lightweight structures to reduce the overall weight of the rail vehicle. The fiber reinforced polymer (FRP) materials possess light‐weightiness, high strength, high stiffness value and are more durable in nature. The researchers are continuously putting their efforts into new innovations in concern towards the replacement of existing conventional materials by FRP composites in railway applications. This review focuses on the overview of FRP composites, the role of composites in past rail vehicles, the rail vehicle component selection and methodology and FRP composites used for various railway components manufacturing with their challenges. Also, this review included the data of FRP composites used in various countries for different railway components applications. Hence, this review is beneficial for the upcoming researchers as a foundation literature to work on railway vehicle applications using variety of FRP materials. Moreover, the challenges are quoted in this review through the comprehensive analysis of literature and hence it provides the information in the form of research gap, so that it would be helpful for the researchers to overcome all the challenges in their upcoming research works. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of Co(II) and Ni(II) mixed ligand complexes are derived from isoniazid, 9-fluorenoneandoxalate. The metal complexes were characterized on the basis of elemental analysis, IR, UV-visible, CV, PXRD, and molar conductance analytical data, viz., all the metal complexes were suggested in an octahedral geometry, respectively. The mixed ligand complexes are formed in the 1:1:2:1 (M:L1:L2:L3) ratios, as found from the elemental analyses, and originate to have the formula [M(L1)(L2)2(L3)]. Where M = Co(II), Ni(II), L1 = isoniazid, L2 = 9-fluorenone, and L3 = oxalate. The molar conductance data reveals that the complexes are non-electrolytes. The cyclic voltammogram of the Co(II) complex revealed that the quasi-reversible single electron transfer process and Ni(II) complex corresponding to a one-electron transfer process were observed during controlled potential electrolysis. IR spectra show that the ligands are coordinated to the metal ions through N and O donor sites of isoniazid-N, 9-fluorenone-O and oxalate-O. Magnetic moment values and UV-visible spectra were used to infer the coordinating of the geometrics of these complexes found to be octahedral. The PXRD patterns suggest that all the complexes are crystalline phases. The metal chelates have been screened for antimicrobial, antioxidant and anti-inflammatory activities, and our findings have been reported, explained and compared with some known antibiotics. [ABSTRACT FROM AUTHOR]

The present experimental investigation focuses on the development of Areca/Sisal/Carbon reinforced epoxy hybrid composites under various stacking sequences and involves the assessment of their mechanical and morphological properties to evaluate their use in some railway interior applications. Nine different combinations of laminates were prepared by using the manual hand layup technique. Mechanical experiments such as tensile, flexural, impact, inter‐laminar shear strength and hardness tests were performed and the results envied the positive values which suggest the use of composites prepared in the study to be employed in some railway interior parts. The morphology of the composites was scrutinized using scanning electron microscopy and exposed the proper agglomeration of fibers in the matrix which in turn has influenced better mechanical properties. The experimental results convey that the hybridization of natural and synthetic fibers in polymer matrix would be an exciting prospect to be utilized in some railway interior applications. [ABSTRACT FROM AUTHOR]

In recent days, natural fiber reinforced polymer composite is more popular due to its extensive properties suitable for various potential applications. The attention towards natural fibers is because of low cost, biodegradable, recyclability, nonabrasive, combustible, lightweight, and nontoxic properties. However, there is a need for furthermore fundamental knowledge for the raw materials processing and fabrication of composite structures, which is still challenging in current days. Natural fiber sources exist all over the world, which is obtained from animals, plants and minerals. The quality of the natural fibers depends on the extraction methods and different processing techniques. These natural fibers surface characteristics could be enhanced by selecting suitable surface treatment and chemical treatment. These fiber treatments reduce the water intake percentage, improve the adhesive nature, and enhance the overall performance of resulting polymer composites. Among all the chemical treatments, alkaline treatment (NaOH) is the most preferred chemical treatment because of its effectiveness and its low cost. This review article proposes the natural fibers detailed classification, composition, structure, properties, and extraction methods, chemical and surface treatments. We also summarize the previous research work findings on the fibers treatment, properties of natural/natural hybrid polymer composites and natural/synthetic hybrid polymer composites with applications. [ABSTRACT FROM AUTHOR]

The continuous delivery of E‐waste from petroleum‐based products creates ecological and environmental problems due to non‐biodegradable polymers, which release harmful chemicals and toxic gases. This results in biodegradable polymers/fibers appearance, which are biocompatible and degrade in the surrounding environments without causing any environmental pollution and these relieve environmental burden. However, the bio‐based materials are unable to meet certain properties in the way of flexibility, dielectric properties, electrical properties, water and gas vapor barrier properties. The current day's research focus is towards the implementation of biodegradable composites properties by introducing different nanostructures. The biopolymers/biofibers are used as raw material in concern with environmental aspects. Nowadays researchers are supplementing a new form of materials known as nanofillers in various biopolymer‐based composites in a small amount. This nanofillers will act as additives and helps in enhancing the different properties such as mechanical, thermal, flame retardancy and water absorption behavior of the nano composite materials as well as maintaining the optimum density of them. The nanocomposites applications are extended in various sectors for the reason of higher surface area, aspect ratio, and superior properties. This review outlines the types of biofibers/biopolymers and their characterization, types of nanofillers, and their characterization, and summarizes the various functional properties of nanocomposites with their applications. [ABSTRACT FROM AUTHOR]

The composite industry was attracted by natural fiber reinforced polymer materials for various valuable engineering applications due to its ecofriendly nature, less cost, and enhanced mechanical and thermal properties. This present work aimed at incorporating sisal and kevlar woven fabrics with the epoxy matrix and studying the effect of Pongamia pinnata shell powder on the sisal/kevlar hybrid composite. Six different laminates were prepared using hand layup method with filler percentage varying 2, 4, and 6 wt%. The prepared laminates cut according to the ASTM standards for performing different mechanical tests. Results reveal that the reduction of void percentage was observed at higher filler contents, while the incorporation of kevlar fabric enhances the impact strength by 279%, tensile strength by 89.77%, and tensile modulus value by 2% in comparison with pure natural fabric laminate L‐1. The flexural strength and interlaminar shear strength were higher for 2% filler composites, while the highest flexural modulus and hardness values were observed for 6% filler‐filled composites. The water absorption percentage was maximum for sisal laminate L‐1 and minimum for kevlar laminate L‐2. The fractured tensile and flexural specimens were analyzed by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

The use of bio‐fiber‐based hybrid composites in various commercial engineering applications is increasing day by day due to their biodegradability and versatile characteristics. Hence, in the present research investigation, an attempt has been made to scrutinize the mongrelizing possessions under different laminate stacking arrangement concerning Phoenix pusilla fibers (PPFs)/E‐glass woven/carbon woven fabric‐reinforced epoxy composite laminates through the studies of density, void fraction, and different mechanical strength behavior evaluation of five resulting diverse hybrid composite laminates. The hybrid laminates were prepared by manual hand lay‐up technique. The scrutinization of physical and mechanical properties and the study of fractured surfaces specify noteworthy improvement in density, void fraction, tensile properties, flexural properties, and microhardness properties of PPFs/E‐glass/carbon fabrics‐reinforced hybrid epoxy composites. The overall results conferred that the composite laminates fabricated in the present study could be potentially used in medium load structural applications. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) is an excellent membrane-forming polymer and can be modified with potato starch and methyl acrylate monomers to obtain copolymers with improved physical and chemical properties. The study presents the synthesis of poly(vinyl alcohol)-g-starch-poly(methyl acrylate) PVA-g-St-g-PMA copolymers using microwave irradiation technique and potassium persulfate initiator. Solution casting and solvent evaporation methods were adopted for the fabrication of polyvinyl alcohol-g-starch-acrylamide composite membranes. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal analysis. The modified nanocomposite membranes were showed very promising results with the parameters permeability and selectivity. The nanocomposite membranes exhibited the advantages of easy handling and reuse. [ABSTRACT FROM AUTHOR]

Here, we report the fabrication of nZVI by the wet chemical technique in the presence of ethanol using ferric iron and sodium borohydride as the reducing agents under ambient conditions. The obtained nZVI particles are mainly in a zero-valent oxidation state and do not undergo significant oxidation for several weeks. The structural and morphological parameters of nZVI were investigated by using UV, XRD, SEM, EDX, TEM, and DLS analysis. The optical nature, bandgap energy, and absorption edge were all revealed by the UV–visible spectrum. The phase development and crystallinity of nZVI particles were shown by the XRD pattern. The morphological investigation revealed that the nanoparticles were spherical with an average size of 34–110 nm by using ImageJ software, and the elemental analysis was analyzed using EDX. Furthermore, the catalytic treatment performance of domestic wastewater was evaluated in terms of pH, COD (chemical oxygen demand) solubilization, total solids (TS), volatile solids (VS), phosphorous, and total nitrogen (TN) reduction under aerobic and anaerobic operating conditions. The effluent was subjected to a process evaluation with a different range (100–500 mg/L) of nZVI dosages. The COD solubilization and suspended solids reduction were significantly improved in the anaerobic condition in comparison to the aerobic condition. Furthermore, the effect of nZVI on phosphorous (PO43−) reduction was enhanced by the electrons of iron ions. The high concentration of nZVI dosing has a positive impact on COD solubilization and phosphorous removal regardless of the aeration condition with 400 mg/L of nZVI dosage. [ABSTRACT FROM AUTHOR]