Synthetic Materials Research Articles

A polylactic acid-carbon nanofiber-based electro-conductive sensing material and paper-based colorimetric sensor for detection of nitrates.

Plastics are ubiquitous in today's lifestyle, and their indiscriminate use has led to the accumulation of plastic waste in landfills and oceans. The waste accumulates and breaks into micro-particles that enter the food chain, causing severe threats to human health, wildlife, and the ecosystem. Environment-friendly and bio-based degradable materials offer a sustainable alternative to the vastly used synthetic materials. Here, a polylactic acid and carbon nanofiber-based membrane and a paper-based colorimetric sensor have been developed. The membrane had a surface area of 3.02 m2 g-1 and a pore size of 18.77 nm. The pores were evenly distributed with a pore volume of 0.0137 cm3 g-1. The membrane was evaluated in accordance with OECD guidelines and was found to be safe for tested aquatic and terrestrial models. The activated PLA-CNF membrane was further used as a bio-based electrode for the electrochemical detection of nitrates (NO3-) in water samples with a detection limit of 0.046 ppm and sensitivity of 1.69 × 10-4 A ppm-1 mm-2, whereas the developed paper-based colorimetric sensor had a detection limit of 156 ppm for NO3-. This study presents an environment-friendly, low-carbon footprint disposable material for sensing applications as a sustainable alternative to plastics.

Inorganic polymers as drug carriers: opportunities and challenges

Innovative methods and significant developments in designing new synthetic inorganic materials have been used to overcome limitations of current drug delivery systems. Inorganic polymers are widely used in the field of biomedicine, imaging, tissue engineering and drug delivery because of their bioactivity, biocompatibility, and stability. A few of the more well-known wholly inorganic polymers are portland cement, silicon dioxide, polyanionic glasses (including titania- and aluminosilicate glasses), poly(sulphur nitride), polycrystalline diamond, graphite, poly(sulphur nitride), and alumi¬num-silicate materials. Inorganic polymers, especially those possessing significant porosity, are good potential candi¬dates for the delivery of several drugs (anticancer, antibiotics, and anti-inflammatories), providing advantages such as encapsulation, controlled delivery, and improved targeting of drugs. Choosing a suitable drug carrier with a selec¬tive targeting potential also seems to be a very promising way for improving stability as well as selectivity. Despite all the advances, developing homogeneous inorganic polymers with narrow molecular weight distributions is a multidis¬ciplinary challenge. The current keynote speech provides a review of the opportunities and challenges of using inor¬ganic polymers as drug carriers.

Overview of biodegradable polymers: synthesis, modification and application

Biodegradable polymeric represents a growing field. Owing to their wide-ranging properties, both synthetic and natural polymeric materials perform a vital and ubiquitous role in everyday life. Amended natural polymeric materials such as starch, cellulose, lignin, chitosan, cottonseed shell (CTS), and cotton gin trash (CGT) have enhanced properties, while synthetic Biodegradable polymeric materials such as poly (vinyl alcohol) (PVA), biodegradable plastics, biodegradable foams. Bioplastics are a kind of polymers able to be degraded by different microorganisms to small molecules (e.g., H2O, CO2, and CH4). Bioplastics are observed to solve waste materials and biodegradability is just a new material to be exploited at the end of its life in specific terms. They should be used for applications that require cheap methods to dispose of items after it has fulfilled their job (e.g., for food packaging, agriculture, or medical products).

Modulating the Transmission of Light Using Asymmetric Janus Particles

AbstractThe ability to manipulate the absorption, scattering, or reflectivity of light using synthetic materials has inspired innovations in nano‐ and micro‐materials for applications ranging from geoengineering to display optics. Asymmetric materials, like Janus particles, offer one solution to meet the needs of such technologies, as composition and geometry can be optimized to maximize directional optical properties in response to magnetic and/or electric fields, light, or electrostatic charge. In this work, a gram‐scale synthesis is applied to generate Janus matchstick particles comprising a gold head with a silica rod. Conditions are explored and optimized to elicit rotation of these matchstick particles under an alternating current (AC) electric field with varying field strength and frequency to maximize particle alignment. While only modest changes in transmission (≈8%) are observed over the visible spectral region with a bare silica rod, the application of an absorbing element increased transmission changes up to ≈23% demonstrating their utility as color‐changing materials. Experimental results are supported by theory and computation and highlight an important first step in activating directional optical effects in these materials which can be optimized for future adaptive technologies.

Mechanical property characterizations of woven natural fiber-reinforced polymers 3D printed through a laminated object manufacturing process

ABSTRACT The mechanical properties of woven natural fiber reinforced polymers additively manufactured through Laminated Object Manufacturing (LOM) technology are investigated in this paper. The benefits of both the material and manufacturing process were combined into a sustainable practice, as a potential alternative to traditional synthetic composite materials made from nonrenewable crude oil with limited end-of-life alternatives. Woven jute fiber reinforcements are used to strengthen both synthetic and bio- thermoplastic polymers in creating highly biodegradable composite structures. Such materials, as one of the prospective alternatives for synthetic composites, can be used in many engineering fields such as automobile panels, construction materials, and commodity and recreational products including sports and musical instruments. A LOM 3D printer prototype was designed and built by the authors. All woven jute/polymer biocomposite test specimens made using the built prototype in this study had their mechanical (both tensile and flexural) properties assessed using ASTM test standards and then compared to similar values measured from pure polymer specimens. Improved mechanical characteristics were identified and analyzed. Finally, SEM imaging was performed to identify the polymer infusion and fiber-matrix bonding conditions.

Fabrication and characterization of mycelium-based composites from Lentinus squarrosulus and Pleurotus ostreatus with improved physico-mechanical properties for versatile applications

This study explores the potential of fungal mycelium-based plate-like composites as sustainable and cost-effective alternatives for synthetic materials. Locally available lignocellulosic waste and fungi isolated locally were used to fabricate mycelium composites. The medium primarily consists of Albizia sawdust and the fungi Lentinus squarrosulus and Pleurotus ostreatus were used. All the composites identified here were subjected to analyses based on scanning electron microscopy, moisture content, dry density, water absorption, flammability, thermal stability, and compression strength following ASTM and ISO standards. The mycelium plates produced with L. squarrosulus mycelium (ASL) exhibited lower dry density and less water absorption. The ASL mycelium plates exhibited a soft and foamy appearance, whereas the P. ostreatus material (ASP) appeared dense mycelium growth only in the top and bottom parts of the plate. The UL-94 rating demonstrated that both samples exhibited superior flame retardancy properties (rated as V1) compared to commercially used expanded polystyrene (EPS). These variations were due to the difference between mycelium density. Therefore, these new bio-composites have the potential to replace conventional packaging or interior construction materials.

Morphometric and histopathological evaluation of modified Elnady's plastinated tissue compared to non-plastinated tissue: Highlighting its relevance for teaching and research.

The present study aims to evaluate the morphometric and histopathological properties of Modified Elnady's plastinated tissue after a period compared to non-plastinated tissue. The plastination technique is utilized in research and teaching due to the potential health risks associated with prolonged exposure to formalin. The tissues and organs are permanently dried during plastination and can be used for further anatomical, histopathological and surgical educational purposes. This method involves drying tissue and allowing synthetic materials like glycerin to permeate it. The study compared non-plastinated and plastinated tissue post-plastination to determine if structural alterations differed from those linked to plastination. The study examined the histopathological examination of dogs' skin, muscles, liver, lung, and intestine using formalin-fixed organs for paraffin embedding and previously plastinated organs for a plastinated group. The study examined non-plastinated and plastinated tissues, their histological composition and biometric parameters revealing typical structures in the non-plastinated group. Plasmodiumted tissues exhibited a compacted appearance, volume changes, nuclear clarity, and cytoplasmic hypereosinophilia, with statistical differences between the two groups. The study reveals that plastinated tissues, after 5 years of plastination, maintain their histological architecture well, with some exceptions. Plastinated tissues can be utilized in future microscopic and immunological studies and will be beneficial for teaching and research.

Manufacturing and Applications of Cellulosic Films in Packaging: An Alternative for Plastic Films

Background: Different synthetic materials are constantly being utilized as raw materials for packaging, which might have several drawbacks, like plastic, some of which have poor lifespans. Plastic can get damaged, scratched, or fractured over time, easily take in tastes and fragrances, and significantly affect the environment and health. Excessive plastic waste may lead to environmental pollution and related consequences. Plastics that contaminate food have also been linked to health problems like high blood pressure, heart palpitations, headaches, nausea, diarrhea, and flushing. Objective: The present review entails the hazards associated with the usage of plastic as a packaging material and highlights the necessity to reduce its use and promote alternatives and sustainable production. Thus, the present review portrays the need for biopolymers, types of plant polymers, methods of cellulose extraction and derivatization, the manufacturing process of cellulosic films and thereby use as film and coatings for food preservation. The current review also summarizes different quality control tests for effective utilization as an alternative to synthetic polymers. Conclusion: Different polymers derived from agricultural products are excellent candidates for creating packaging materials. Similar to polysaccharides, these polymers, including nanocomposites, films, composites, etc., are helpful in a wide range of applications. Cellulose, one of the most widespread polysaccharides in the world, offers a variety of appealing special qualities. It appears reasonable and must be considered that cellulose can be used effectively as a raw material for packaging. In this review, we explore how cellulose is used in the packaging industry to make composites, coating materials, and edible and non-edible films.

Exploring the role of surface and porosity in CO2 capture by CaO-based adsorbents through response surface methodology (RSM) and artificial neural networks (ANN)

In this study, synthetic CaCO3 materials were utilized as precursors for CaO-based CO2 sorbents. The investigation examined how various operating parameters—such as synthesis temperature (ST), stirring rate (SR), and surfactant percentage (SP)—impact the properties of the adsorbents. Samples were firstly characterized by X-ray diffraction and Scanning Electron Microscopy (SEM), which revealed that the prevalence of calcite or aragonite crystal phases in the synthetic CaCO3 precursors can be tuned by adequately choosing the dose of surfactant (Triton-X100®), so that it can be used as a crystal habit and growth modifier. The calcination process applied to the CaCO3 precursors leads to the formation of partially sinterized cubic crystals of CaO, accompanied by minor quantities (< 5 %) of additional compounds like Ca(OH)2 or CaSO4. Specific surface area (SBET) and porosity were determined by measuring the N2 adsorption isotherms. A CaCO3 sample with an unprecedented value of SBET as large as 116 m2/g was prepared operating under optimal conditions. SBET and pore volumes were successfully correlated with the CO2 uptake capacity of the samples. SBET is more influential for experiments carried out under diluted CO2 atmosphere. When pure CO2 is used, the influence of meso- and micropore volumes (Vme and Vmi) is clearly predominant, which suggests that in this latter case diffusion through the porous texture of the samples plays a more remarkable role. A double-way approach through Response Surface Methodology (RSM) and the use of Artificial Neural Networks (ANNs) has been used to analyze the CO2 uptake capacity of the samples. Within the operational interval, excellent results were obtained for pure and diluted CO2 flow, and RSM and ANNs have demonstrated to be a very efficient tool to correlate the behavior of the CaO-based materials as CO2 sorbents with the surface area and pore volumes of the samples. Valuable information on (i) the importance of the different factors under study; (ii) their influence on the surface and porosity of the CaO-derived sorbents; and (iii) the subsequent CO2 capture performance of the sorbents has been obtained. The results suggest that four parameters have a statistically significant influence on CO2 uptake. These parameters are SR, the square of SR, its interaction with SP, and the square of SP. Additionally, the study assessed the stability of the CaO-based sorbents over 11 consecutive calcination-carbonation cycles. By adequately choosing the synthesis strategy and conditions, an almost negligible shrinkage effect can be achieved, resulting in a more sustained uptake capacity throughout the cycles.

Characterization of Novel Natural Cellulose Fiber from Ficus Macrocarpa Bark for Lightweight Structural Composite Application and Its Effect on Chemical Treatment.

This study investigates Ficus Macrocarpa tree bark fibers (FMB) as a sustainable alternative reinforcement for polymer composites. The Industrial Revolution marked the evolution of polymer composites with synthetic material reinforcement, leading to environmental concerns. Natural fibers have recently gained prominence as efficient alternatives for polymer composites. Despite numerous natural fibers being considered, ensuring a sustainable raw material source remains crucial. In this study, fibers were extracted from FMB and subjected to alkali treatment to evaluate their impact on physical, chemical, and thermal properties. Initially, the extracted fibers measured 253.80±15 μm in diameter, reduced to 223.27±12 μm post-alkali treatment. Chemical analysis showed an increase in cellulose content to 59.7wt.%, a 23.34% improvement over untreated fibers (48.4wt.%). The crystalline index for untreated and treated fibers measured 80.20% and 84.75%, respectively, with no noticeable changes in the cellulose phase. Additionally, the crystalline size increased to 3.21nm. Thermogravimetric analysis demonstrated enhanced stability of treated fibers up to 378.87ºC, while the kinetic activation energy remained constant at 64.76 kJ/mol for both the treated and the untreated fibers. The alkali treatment further improved surface roughness to 39.26, confirmed by scanning electron microscopic images. These findings highlight the potential of cellulose fibers from Ficus Macrocarpa bark as a sustainable and environmentally friendly replacement for synthetic fibers in polymer composites. The enhanced physical properties and excellent thermal stability make them a promising choice for eco-conscious materials.

Classification of geologic materials used in the Sukhothai Historical Park of Thailand using a portable X-ray fluorescence analyzer and petrographic analysis

The Sukhothai Historical Park, designated as a world heritage site in Thailand, encompasses the remnants of the Sukhothai Kingdom and serves as a valuable locus for geological and geoarchaeological investigations. Situated in the Sukhothai province, the region is characterized by diverse lithologies, including slate, phyllite, and laterite, as well as red bricks (synthetic materials), utilized in the construction of various ancient structures. Petrographic analysis using polarized light microscopy reveals the phyllites as the primary dimension stones, exhibiting foliated and mylonitic textures with small quartz augen. A portable X-ray fluorescence analyzer was employed for geochemical analysis and the analysis of major oxides and trace elements. The resulting data facilitated the classification of protoliths and comparison with rocks from an abandoned quarry near Saritphong Dam in the western part of the historical park. Notably, phyllites utilized in several prominent structures within the park; Wat Saphan Hin, Wat Pa Daeng 2, Wat Thap Sakae, Wat Chetuphon, Wat Sri Chum, and Wat Mangkorn Temples, exhibited similar characteristics to those in the Wat Khao Noi old quarry, as confirmed by Rubidium (Rb) and Strontium (Sr) values. The SiO2/Al2O3 and FeO/K2O ratios were pivotal in identifying the protoliths of the studied phyllites as shales. In summary, the primary dimension stones for Sukhothai Historical Park originated from the western mountain within the park, with laterites sourced from foothill areas. The presence of quartz pebbles in red bricks suggests local sediment utilization, and quartz additions were employed to enhance structural strength. This comprehensive geoarchaeological study sheds light on the geological composition of the Sukhothai Historical Park, providing valuable insights into the selection and utilization of construction materials in this historically significant site.

Impact of Hazardous Chemical Compounds on the Reproductive System Reported in Sanitary Products

Abstract: A particular group of routine essentials, feminine hygiene items, might expose women to plasticizers and antimicrobial agents. The entire world produces and uses a vast amount of chemicals, some of which may be harmful to reproductive health. The majority of chemicals and work environments have not been investigated for their potential to harm reproductive systems up to this point. The Republic of Korea and other recently industrialized nations have accumulated chemicals and other toxicants quickly, endangering well-being, especially their reproductive systems. (UTC) Women frequently utilize feminine hygiene products (FHPs) as personal care products. ( 2 )According to a broad review, sanitary pads have an impact on endometriosis, vaginal microflora, and vulvar or vaginal skin. Female health has also been found to be impacted by social contexts, such as the use of hygiene products or puberty education. (temp) Chemicals that are dangerous now or in the future are included in the category of sanitary products. Infertility, ovarian cancer, skin rashes, and skin darkening are just a few of the problems that can arise from using sanitary products that contain hazardous chemicals and harm the reproductive system. menstrual cycle imbalance. Sanitary products contain a variety of substances, including VOC, furans, phthalates, bisphenols, and dioxin. Jppd Diapers and sanitary pads are composed of synthetic plastic materials, which may leak when being used. In the present study, the quantities of phthalates (DBP, DEHP, DEP, and BBP) and volatile organic compounds (VOCs) (methylene chloride, toluene, and xylene) in sanitary pads and diapers were measured.

Biocomposite thermoplastic polyurethanes containing evolved bacterial spores as living fillers to facilitate polymer disintegration

The field of hybrid engineered living materials seeks to pair living organisms with synthetic materials to generate biocomposite materials with augmented function since living systems can provide highly-programmable and complex behavior. Engineered living materials have typically been fabricated using techniques in benign aqueous environments, limiting their application. In this work, biocomposite fabrication is demonstrated in which spores from polymer-degrading bacteria are incorporated into a thermoplastic polyurethane using high-temperature melt extrusion. Bacteria are engineered using adaptive laboratory evolution to improve their heat tolerance to ensure nearly complete cell survivability during manufacturing at 135 °C. Furthermore, the overall tensile properties of spore-filled thermoplastic polyurethanes are substantially improved, resulting in a significant improvement in toughness. The biocomposites facilitate disintegration in compost in the absence of a microbe-rich environment. Finally, embedded spores demonstrate a rationally programmed function, expressing green fluorescent protein. This research provides a scalable method to fabricate advanced biocomposite materials in industrially-compatible processes.

Hybrid Materials for Vascular Applications: A Preliminary In Vitro Assessment

The production of biomedical devices able to appropriately interact with the biological environment is still a great challenge. Synthetic materials are often employed, but they fail to replicate the biological and functional properties of native tissues, leading to a variety of adverse effects. Several commercial products are based on chemically treated xenogeneic tissues: their principal drawback is due to weak mechanical stability and low durability. Recently, decellularization has been proposed to bypass the drawbacks of both synthetic and biological materials. Acellular materials can integrate with host tissues avoiding/mitigating any foreign body response, but they often lack sufficient patency and impermeability. The present paper investigates an innovative approach to the realization of hybrid materials that combine decellularized bovine pericardium with polycarbonate urethanes. These hybrid materials benefit from the superior biocompatibility of the biological tissue and the mechanical properties of the synthetic polymers. They were assessed from physicochemical, structural, mechanical, and biological points of view; their ability to promote cell growth was also investigated. The decellularized pericardium and the polymer appeared to well adhere to each other, and the two sides were distinguishable. The maximum elongation of hybrid materials was mainly affected by the pericardium, which allows for lower elongation than the polymer; this latter, in turn, influenced the maximum strength achieved. The results confirmed the promising features of hybrid materials for the production of vascular grafts able to be repopulated by circulating cells, thus, improving blood compatibility.

Studies on the SYNTHETIC Method of 2,5-Dihydroxyterephthalaldehyde

 2,5-Dihydroxyterephthalendehyde (Dha) can be used as an intermediate in organic chemistry and synthetic materials, which can participate in a variety of chemical reactions. Through these reactions, a variety of valuable compounds can be synthesized. However, the existing synthesis methods are cumbersome, difficult to operate, and have low yields. Referring to the reported Dha synthesis process, we successfully synthesized Dha using inexpensive 1,4-dimethoxybenzene with simple steps. The correct structure was proved by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (1H-NMR) hydrogen spectroscopy, and nuclear magnetic resonance (13C CP-MAS NMR) carbon spectroscopy, which provides a valuable reference for the synthesis of Dha.

Potential benefits of adipose–derived SVF and MSCs to regenerate damaged tissues from alloplastic synthetic materials

Recent advancements in Plastic Surgery and Regenerative MedicineQuery have revolutionized tissue repair, remodeling, and regeneration. A promising approach involves Mesenchymal Stem cells and from the adipose–derived Stromal Vascular Fraction, aimed at improving tissue healing post the use of synthetic materials. This integration shows potential in mitigating adverse effects of synthetic materials like dermal fillers, offering new clinical interventions for tissue repair and regeneration. This article explores the benefits, complications, and applications of these technologies in Plastic Surgery and Cosmetic Medicine, focusing on their mechanisms of action and future perspectives.  Level of evidence: Not ratable

Heterogeneous and Cooperative Rupture of Histidine-Ni2+ Metal-Coordination Bonds on Rationally Designed Protein Templates.

Metal-coordination bonds, a highly tunable class of dynamic noncovalent interactions, are pivotal to the function of a variety of protein-based natural materials and have emerged as binding motifs to produce strong, tough, and self-healing bioinspired materials. While natural proteins use clusters of metal-coordination bonds, synthetic materials frequently employ individual bonds, resulting in mechanically weak materials. To overcome this current limitation, we rationally designed a series of elastin-like polypeptide templates with the capability of forming an increasing number of intermolecular histidine-Ni2+ metal-coordination bonds. Using single-molecule force spectroscopy and steered molecular dynamics simulations, we show that templates with three histidine residues exhibit heterogeneous rupture pathways, including the simultaneous rupture of at least two bonds with more-than-additive rupture forces. The methodology and insights developed improve our understanding of the molecular interactions that stabilize metal-coordinated proteins and provide a general route for the design of new strong, metal-coordinated materials with a broad spectrum of dissipative time scales.

Release of fibrous microplastics from functional polyester garments through household washing

The global increase of the amount of microplastics in aquatic systems is an ever-growing problem. Household laundering of synthetic textiles has been identified as one significant reason for the release of fibrous microplastics (FMP), although a high proportion of the waste water generated by the washing process is filtered by wastewater treatment plants, e.g., in Germany, before it enters the environment. The washing of garments made of synthetic materials is considered particularly and was investigated during this study. Therefore, 11 fleece garments, one mixed batch and three non-raised garments were washed several times and under different conditions in houshold washing machines. However, this study utilizing different functional polyester garments showed that mechanical raised textiles (e.g., fleece) do not generally have higher emission values than non-raised textiles, such as sports shirts and sports pants. During the washing process, the release of FMP can be influenced by different washing parameters, always aiming for a good washing result. The experiments showed, that the release of FMP into the aquatic environment can be reduced by the washing habits—especially a high washing machine load and a shortened washing time were found to be effective.

Micro/nano fillers for value‐added polymer composites: A comprehensive review

AbstractThe need for new sustainable engineering materials using polymer composites is evolving every day. Researchers are in a race to develop value‐added products from natural renewable sources and discarded waste materials. Studies indicate several hurdles while trying to provide ecologically friendly materials for product manufacturing over the years. Natural materials are more readily available, biodegradable, more affordable, have less processing health hazards, and are more environmentally friendly than synthetic materials. As the price of commercial polymers decreased, the incorporation of fillers became increasingly necessary for technical reasons.. The market for polymers can actually be expanded by appropriately combining fillers and polymers to produce a wide range of qualities in these two components. This review provides an overview on a variety of organic and inorganic fillers which were incorporated into the polymer composites and their influence on the physical, chemical, mechanical, thermal, and electrical properties of polymer composites by various characterization methods and their In fact, it is possible to achieve a wide range of qualities in these two components by appropriately combining polymers and fillers, which expands the market for which polymers may be employed.application scopes. This review aims to thoroughly examine and assess various polymer and filler combinations, with a particular emphasis on their potential suitability for a range of engineering and industrial applications. These encompass microelectronics, biomedical fields, flexible electronics, flame retardant uses, food packaging, automotive and aerospace sectors, as well as applications within the construction industry for structural and semi‐structural purposes.Highlights New polymer composite engineering materials with long‐term sustainability Value‐added product development from renewable resources and discarded waste materials. Provide information to select appropriate reinforcements for composite manufacturing. Diverse discussion on the application of fillers and their composites.

Family behavior and Dirac bands in armchair nanoribbons with 4–8 defect lines

Bottom-up synthesis from molecular precursors is a powerful route for the creation of novel synthetic carbon-based low-dimensional materials, such as planar carbon lattices. The wealth of conceivable precursor molecules introduces a significant number of degrees-of-freedom for the design of materials with defined physical properties. In this context, a priori knowledge of the electronic, vibrational and optical properties provided by modern ab initio simulation methods can act as a valuable guide for the design of novel synthetic carbon-based building blocks. Using density functional theory, we performed simulations of the electronic properties of armchair-edged graphene nanoribbons (AGNR) with a bisecting 4–8 ring defect line. We show that the electronic structures of the defective nanoribbons of increasing width can be classified into three distinct families of semiconductors, similar to the case of pristine AGNR. In contrast to the latter, we find that every third nanoribbon is a zero-gap semiconductor with Dirac-type crossing of linear bands at the Fermi energy. By employing tight-binding models including interactions up to third-nearest neighbors, we show that the family behavior, the formation of direct and indirect band gaps and of linear band crossings in the defective nanoribbons is rooted in the electronic properties of the individual nanoribbon halves on either side of the defect lines, and can be effectively through introduction of additional ‘interhalf’ coupling terms.