Nacre Research Articles

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Theme: Motherhood and Mothering. Ill. ©Stina Wirsén The Fox Hunter and the Mother of Pearl: Motherhood and Biology in the Works of Kitty Crowther This article examines the biological aspect of motherhood in Kitty Crowther’s writing, in particular L’enfant racine (2003; The Root Child) and Mère Méduse (2014; Mother Medusa). By paying attention to the intertextual relations and the metaphorical aspects ​​of the images, the analysis demonstrates how Crowther’s iconotext relates to a conflict-filled discourse about mothering and biology. The two works in focus activate dissimilar intertexts, which share references to fertility and pregnancy. L’enfant racine is based on folklore, such as the Czech fairy tale “Otesánek” and Queen Mab. In Mère Méduse the story of Poseidon’s/Neptune’s rape of Medusa in Roman-Greek mythology constitutes an implicit prehistory to the narrative. The two books build up different kinds of symbolism, where a common point is the depiction of parenthood as a more or less organic relationship. In L’enfant racine, it is a hen-chasing fox who lures the soon-to-be adoptive mother into a mysterious forest, and once she finds the child Root, he is literally bereft of his roots. In Mère Méduse, the central symbol is the mother’s living hair, forging an organic bond with the child. Added to this is a play with literal and figurative representations based on the properties of the jellyfish and the mussel’s defence against pebbles through the creation and enclosing of a pearl – in mother of pearl. Crowther’s iconotexts transform conventional symbolism, thus calling for a reflection on the words and images which are used in our culture to speak of motherhood.

Thalassotherapy as a multidirectional form of marine resources therapy

Thalassotherapy is a treatment that uses the natural gifts of the sea (climate, air, sea sand, algae, some species of sea fish, mother of pearl) and physical factors (hydrotherapy, heliotherapy, aerosol therapy, music therapy, kinesitherapy and others). It is mainly intended for people who are stressed, overtired and have sleep problems. Thalassotherapy is also used in the treatment of rheumatism, back pain, lung diseases, heart diseases and skin dermatoses, such as psoriasis or atopic dermatitis. These treatments are widely used in wellness centers as care and therapeutic treatments for problematic skin. In cosmetology, preparations of marine origin are also used in the form of masks, peeling creams intended for dry, oily, gray, mature or poorly nourished skin.

Investigations on compression behavior of fused filament fabricated hybrid biomimetic structures

The objective of this study is to design a biomimetic hybrid structure inspired by nacre, and conch shells and compare how the compressive characteristics change when key geometric design parameters are varied. Nacre, also known as mother of pearl, has a host of traits, suitable for survival, like its stiffness and strength. Conch, which is a common name for a number of sea snails, possesses a unique cross-lamellar structure which has a tough outer layer to resist penetration from the sharp-toothed attacks of predators, and a nacreous inner layer which can dissipate energy. A novel nacre–conch–nacre inspired sandwich core structure is designed and fabricated with fuse filament fabrication using acrylonitrile styrene acrylate filament according to the ASTM C365 standard for the flatwise compression test of sandwich core structures. Three key design parameters, namely the wall thickness, the thickness between two nacre walls, and the angle of conch were selected and varied to form nine different iterations of this design. An Abaqus finite element analysis was validated by experimental testing using an Instron 8801 servo-hydraulic universal testing machine. The results showed that conch-inspired structures’ compression properties depend on wall thickness and angle. The sample with 2 mm wall thickness and 45° conch angle had the highest compressive strength of 3.62 MPa, while the sample with 1 mm wall thickness and 50° conch angle had the lowest at 2.09 MPa. These findings suggest this structure could be used in lightweight armor, car, and aerospace parts.

Shocks within a Pacific island fishery: A historic study of events impacting the mother-of-pearl fishery in Papua New Guinea

Local, regional, and global events have potential to disturb fisheries systems embedded within international trade networks. Events associated with sudden and unexpected disturbances, or shocks, in fisheries systems are of particular concern because of their potential to adversely impact the livelihoods and well-being of coastal communities. For these communities in the Pacific region, export-oriented mother-of-pearl (MoP) fisheries have been, and remain, of great economic importance with additional dietary benefits. A lack of information and understanding of events associated with shocks in MoP production and trade, however, limits the ability to predict reactions and to develop appropriate responses to future economic, environmental, or political change. We conducted an integrated assessment of historic MoP export data from 1888 until present (2020) for the largest producer in the Pacific region, Papua New Guinea, to detect shocks and identify associated events. Absence of a trend in the frequency or magnitude of detected shocks and the range of associated events identified suggest that shocks are intrinsic to MoP fisheries systems, and that shocks occur due to varied, often multiple synchronous, events. Critically, legislated policy changes to gear restrictions, licensing, ports of export, size limits, and spatial limits were never associated with shocks, while changes to permitted taxa and export tariffs were implicated in triggering, or contributing to, shocks in MoP exports. The historical assessment of shocks undertaken in this study may aid management agencies in identifying potential risks and appropriate responses to build resilience in MoP fisheries systems, and in artisanal fisheries systems more broadly.

Jewellery Workshops on Elephantine

The settlement of Elephantine in southern Egypt is one of the few places where a local jewellery production made from different materials can be documented. In particular, semiproducts and production waste suggest the manufacture of bracelets and beads from stone and faience from the late Old Kingdom onwards. The production waste also allows for the reconstruction of the way hippopotamus ivory was cut into bracelets. A jewellery workshop can be identified as one of the functions of a large building dating to the Thirteenth Dynasty. Here, raw materials from the surrounding desert regions, i.e., amethyst and ostrich eggshells, were processed into beads, pendants, and scarabs. Various stages of a production line show how the ostrich eggshells were made into beads. The raw material and an unfinished scarab indicate the manufacture of amethyst objects. Semiproducts in the neighbouring houses show that in that area, pendants were also cut from mother of pearl.

Silk imitates mother of pearl for a tough, eco-friendly material

Silk imitates mother of pearl for a tough, eco-friendly material

Influence of production method on the profitability of mabé pearl farming using traditional and research-informed nucleus implanting practices with the winged pearl oyster, Pteria penguin

Mabé pearl culture has become a significant addition to traditional rural livelihood activities in Tonga and in other south Pacific countries. Mabé pearl culture is a low-cost, low-tech alternative to round pearl culture, can be undertaken by local people with minimal training, and has considerable potential for value adding through production of jewellery and handicraft items. Mabé pearls are produced by attaching hemispherical nuclei to the inner shell surface of pearl oysters where subsequent coverage with nacre (mother of pearl) produces commercial pearls after a culture period of around 12 months. Traditionally, local mabé pearl farmers attempt to maximise pearl output by implanting four high-profile nuclei into each oyster. Recent research has indicated that fewer nuclei, and those with lower profile, may improve the overall quality of resulting mabé pearls and this has been adopted as best-practice by Tongan mabé pearl farmers. This study reports an economic comparison of these two nucleus implanting arrangements. Results showed that annual returns were not dissimilar with the traditional implanting method (four high-profile nuclei) generating USD 6977 per annum, while the recommended best-practice method (two low-profile, one high-profile nuclei) generated USD 6795 per annum. While the traditional method may generate potentially higher annual returns, there are two key considerations that favour the best-practice method: (1) reduced labour commitment that provides opportunity to engage in other livelihood activities; and (2) the production of a higher grade of pearls is more supportive of developing high value export markets for Tongan mabé pearls.

Pearl and Mother of Pearl in Hispania: Exploitation and Trade of Marine Luxury Products

This article analyses the exploitation of luxury products such as pearls and mother of pearl, a seldom-examined facet of maritime archaeology. This issue will be approached from an archaeology of production perspective, taking into account the whole chaine operatoire, including harvesting the resource, marketing it, and mounting it in different supports. We shall also examine the meaning of these resources and some extravagant practices for which they were used during antiquity. We shall pay special attention to the artisans, as well as the production methods used to process these resources and assemble them. The study will focus on the Roman period, and Hispania will be used as case study. The Iberian Peninsula is surrounded by plentiful seas, but this specific issue had been paid no specific attention to date. An unpublished catalogue of jewels decorated with pearls and other ornaments is presented, which confirms the importance of these resources in ancient Roman markets.

The mother of all techniques

Iridescent mother of pearl sports a complex structure that eludes standard imaging techniques. Now, a nanotomographic method provides high resolution 3D insight into the topological defects underpinning this composite material.

The Inrō Collection in the Náprstek Museum

Small several-compartment cases called inrō were a supplement to Japanese men‘s clothing during the Edo period and were used to store various small items (especially personal stamps). Decorated with various techniques, such as decorating with gold, nacre (mother of pearl), and inlaying with metals, they gradually became a decorative accessory for Japanese clothing. In the 19th century inrō became favorite collector’ items in Europe. This article deals with inrō collection in the Naprstek Museum, its origin, but also with the techniques of inrō production.

Nacre Is a Liquid-Crystal Thermometer of the Oceans.

Nacre, or mother of pearl, is a biomaterial with a layered structure. In a recent geological study, researchers found that the width of the nacre layers depends on the formation temperature, which is determined by the ocean water temperature. A linear dependence of layer width with respect to temperature is understandable within the transient liquid-crystalline nature of incipient nacre. Thus, developing nacre is a liquid-crystal thermometer recording its formation temperature. A more complete understanding of nacre formation is of interest not only for biology and geology, in terms of biomineralization and paleoclimatology, but also for materials science: for reproducing nacre or fabricating synthetic analogues and also potentially for developing new classes of layered materials with layer spacings tunable by pH and temperature.

Informing Artisanal Pearl and Pearl-Shell Handicraft Production for the Cruise Tourism Market Through Analysis of Intended Purchase Behavior

The production and vending of handicrafts by the indigenous peoples of cruise destinations in the Pacific region has unrealized potential. Handicraft sector development strategies are constrained by the limited information guiding what products to produce, which product attributes are important, and appropriate pricing for the cruise tourism market. Using structured interviews, we evaluate cruise passenger preferences and intended purchase behavior towards a range of mabé pearl and motherof-pearl (MoP) handicrafts. Our study is conducted in a newly emergent cruise destination, Papua New Guinea, where cruise passenger demand for handicrafts, purchased as souvenirs, goes largely unmet. The majority of cruise passengers expressed both interest and willingness in purchasing mabé pearl and MoP handicrafts, though preferences were found to exist for specific products and product attributes. Latent factor analysis revealed cruise passenger preferences could be summarized by the importance an individual assigned to a handmade product, a product with accompanying information, or the aesthetic appeal of a product. The importance assigned to these factors was found independent of cruise ship and passenger demographics, but partly explained by purchase intent (i.e., purchase for self or others). Factoring these results into handicraft development strategies will help maximize local economic benefits from pearl industries and cruise tourism in Papua New Guinea, but also throughout the Pacific region.

Sliding Avalanches Between Nacreous Tablets.

Nacre, also known as mother of pearl, possesses extraordinary mechanical properties resulting from its intriguing hierarchical brick-and-mortar microstructures. Despite prior studies, interactions between nanoasperities during sliding still need to be elucidated. In this study, we measure slip events between nanograins of microlayers at high temporal resolution during torsion-induced sliding. We model the slips as avalanches caused by interactions of atoms on nanograin surfaces, from which power laws and scaling functions describing statistics and dynamics of slip events are studied. The largest avalanche occurs when nanograins leave each other after the maximum contact. The agreement between measurements and predictions shows that avalanches act essentially in the inhomogeneous sliding of nacreous tablets. Further insights into nanofriction provided in this work may lead to the development of nanoscale tribological systems.

RICERCHE STORICO-ARCHEOLOGICHE DELL’UNIVERSITÀ CATTOLICA DI MILANO SUL DELTA DELL’INDO (2010-2018)

RICERCHE STORICO-ARCHEOLOGICHE DELL’UNIVERSITÀ CATTOLICA DI MILANO SUL DELTA DELL’INDO (2010-2018)

Layered nanocomposites by shear-flow-induced alignment of nanosheets.

Biological materials, such as bones, teeth and mollusc shells, are well known for their excellent strength, modulus and toughness1-3. Such properties are attributed to the elaborate layered microstructure of inorganic reinforcing nanofillers, especially two-dimensional nanosheets or nanoplatelets, within a ductile organic matrix4-6. Inspired by these biological structures, several assembly strategies-including layer-by-layer4,7,8, casting9,10, vacuum filtration11-13 and use of magnetic fields14,15-have been used to develop layered nanocomposites. However, how to produce ultrastrong layered nanocomposites in a universal, viable and scalable manner remains an open issue. Here we present a strategy to produce nanocomposites with highly ordered layered structures using shear-flow-induced alignment of two-dimensional nanosheets at an immiscible hydrogel/oil interface. For example, nanocomposites based on nanosheets of graphene oxide and clay exhibit a tensile strength of up to 1,215±80 megapascals and a Young's modulus of 198.8±6.5gigapascals, which are 9.0 and 2.8 times higher, respectively, than those of natural nacre (mother of pearl). When nanosheets of clay are used, the toughness of the resulting nanocomposite can reach 36.7±3.0megajoules per cubic metre, which is 20.4 times higher than that of natural nacre; meanwhile, the tensile strength is 1,195±60megapascals. Quantitative analysis indicates that the well aligned nanosheets form a critical interphase, and this results in the observed mechanical properties. We consider that our strategy, which could be readily extended to align a variety of two-dimensional nanofillers, could be applied to a wide range of structural composites and lead to the development of high-performance composites.

AVALIAÇÃO DE CONCHAS DO MEXILHÃO Perna perna VISANDO AO APROVEITAMENTO NO DESIGN E ARTESANATO

Este trabalho visou avaliar conchas do mexilhão Perna perna, cultivadas e não cultivadas, para uso em design e artesanato. As amostras vieram de descartes em locais específicos em Niterói, no Rio de Janeiro. Registrou-se a superioridade das conchas cultivadas quanto à simetria, qualidade do nácar e padronização no formato e tamanho. O uso desse resíduo oferece uma oportunidade para o desenvolvimento comunitário, além de ser uma alternativa de mitigação válida para reduzir o impacto do descarte de conchas na natureza.Palavras-chave: resíduos sólidos, madrepérola, sustentabilidade.

Overview of the Development and Modern Landscape of Marine Pearl Culture in the South Pacific

Natural marine pearls were a rare and valuable by-product of a fishery targeting pearl oyster shells for their mother-of-pearl (MOP). This fishery developed around the world throughout the 18th century and increased significantly through the 19th century in Australia and the Pacific islands. Overfishing of the MOP resource led to the development of pearl oyster spat (juvenile) collection techniques to assist stock replenishment. Although the MOP industry eventually ceased in the 20th century, spat collection provided a basis for pearl culture industries in the Pacific, that used nucleated pearl culture techniques developed in Japan. Today, French Polynesia is the largest producer of cultured round pearls in the South Pacific using the endemic black-lip pearl oyster Pinctada margaritifera. The successful French Polynesian pearl industry was a catalyst for development of pearl culture in other Pacific island countries such as the Cook Islands and Fiji. As well as significant export income, pearl culture offers livelihood opportunities (upstream and downstream) to coastal communities at a number of levels, including collection of pearl oyster spat (juveniles) for on-selling to pearl farms, and jewelry and MOP shell craft production. Despite being compatible with local lifestyles, round pearl culture has significant barriers to entry, including high initial investment, high operational costs, and requirement for a high level of technical skills. Alternatively, significant opportunities for coastal communities exist from production of mabé pearls (half pearls) because although not as valuable as high-grade round pearls, they are cheaper to produce, demand fewer technical skills, and pearls can be produced by local people with minimum training. Diversification of round pearl farms into mabé pearl production, or the establishment of stand-alone mabé pearl farms, is increasingly prevalent in Pacific pearl-producing nations, motivated by risk minimization, a broader market base, and a much simpler and less costly industry entry pathway.

Giant cells and osteoclasts present in bone grafted with nacre differ by nuclear cytometry evaluated by texture analysis.

Nacre (mother of pearl) is a natural biomaterial used to prepare orthopedic devices. We have implanted screws and plates made with nacre in five sheeps. Bone were harvested after two months and embedded in poly(methyl methacrylate). Blocks were saws and the thick slabs were grinded, polished and surface stained. Sections were photographed at an ×1000 magnification. Giant cells were found in contact with nacre in eroded areas and true osteoclasts were found at distance in the neighboring bone in Howship lacunae. A texture analysis of the nuclei of giant cells and osteoclasts was done using the run-length method of the MaZda freeware. The size of the nuclei was reduced in osteoclast and their mean gray level appeared reduced. Texture analysis revealed that chromatin had a completely different pattern in giant cells when compared to osteoclasts. Giant cells had a fine repartition of the chromatin with large clear areas around prominent nucleoli. On the contrary, osteoclast nuclei had chromatin blocks evenly dispersed in the nuclei. This reflects the different origin of these cells expressing different functions.

La explotación de ostras perlíferas en Costa Rica (América Central) desde la conquista hasta inicios del siglo XXI:: historia, conquiliología y algunas reflexiones

Costa Rica had an important, high quality pearl industry at international level. Additionally, there was intense exploitation of the nacre shell (mother of pearl) during the XIX century. The fame of our pearls as well as their trade significantly decreased during the first quarter of the XX century, it all but ended possibly due to overexploitation and lack of trade caused by the decrease of their value brought about by the cultured pearls industry. Costa Rican pearls were intensely extracted from the Santa Elena, Culebra and El Coco bays as well from the Nicoya gulf. The most abundant pearl producing species in the region is Pinctada mazatlanica as well as some populations of Pteria sterna. Nowadays, Pinctada mazatlanica is extracted in an artisanal fashion in Santa Elena’s bay both as food and for its pearls. However, there is no clear data about the importance of the current market, so specialized studies (biological and economical) aiming to determine if this market could be reestablished sustainably for the local populations are recommended.

Inside Back Cover: Laser imaging polarimetry of nacre (J. Biophotonics 10/2018)

Nacre, or mother of pearl, is a complex self‐assembled biomaterial that has high resistance against breakage. It is made of micronsized aragonite‐crystal tablets embedded in organic matter, in a brick‐and‐mortar type of structure. Analysis of the transformation of polarized light passing through this natural structure reveals the great uniformity of the layered arrangement of bivalve nacre (left image), and quite distinctly, the non‐uniform columnar structure of gastropod nacre (right image).Further details can be found in the article by Joshua A. Jones, Rebecca A. Metzler, Anthony J. D'Addario et, al. (e201800026). image