Conch Shell (Turbinella pyrum) Powder: A Potential Marine Biological Source of Calcium and Some Trace Minerals for Growing Crossbred Calves.

The present study was conducted to evaluate the effect of feeding conch shell (Turbinella pyrum) powder (either fresh or calcined) as a marine organic source of calcium (Ca) supplemented in the diet of crossbred calves on voluntary intake, growth performance, and blood biochemistry in growing crossbred Jersey calves. A growth trial of 90 days was conducted on 15 Jersey crossbred female calves (Av. weight, 70.68 ± 2.90 kg; Av. age, 197.73 ± 12.40 days), equally divided into three groups of 5 animals each, i.e., control (T0), treatment 1 (T1), and treatment 2 (T2). All animals were fed total mixed ration (TMR) prepared with a concentrate mixture, chaffed paddy straw, and green fodder at the ratio of 40:30:30 on DM basis. Calves under the control group were fed with TMR containing a standard mineral mixture having dicalcium phosphate (DCP) as a Ca source. Calves under T1 group were supplemented with TMR containing fresh conch shell powder (FCSP), and T2 calves were fed with TMR containing conch shell calcined powder (CSCP) as Ca source. We observed 11.66% increase (p < 0.01) in Ca concentration in CSCP compared to FCSP. The concentration of minerals like Mg, Co, Mn, and Fe was enhanced in CSCP compared to the FCSP. However, the calcination process of fresh conch shell powder (FCSP) reduced the concentration of Cu, and Zn. The Ca/P ratio was estimated as 2.11, 2.06, and 2.10 in T0, T1, and T2 diets, which could be considered ideal for calf ration. Calves under T1, and T2 groups consumed significantly (p < 0.001) greater amounts (g/kg W0.75) of DM and CP compared to T0. However, increased voluntary intake did not translate into increased body weight gain (kg), and feed conversion ratio (kg DMI/kg gain) in T1 and T2 groups in comparison to T0. We observed similar blood glucose, urea, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine transaminase (ALT) concentration among the three treatments. Ca, and P levels in blood plasma were also identical among the three groups. The digestibility of Ca was increased significantly (p = 0.01) in FCSP (T1)- and CSCP (T2)-treated calves compared to control (T0) calves. Similarly, T1 and T2 enhanced P digestibility compared to T0. This first report with short-term experimentation depicted some promising scope for the use of locally available conch shell powder (fresh or calcined form) as a potential source of Ca for feeding to livestock, because these new sources of Ca did not affect intake, digestibility of Ca and P, growth performance, blood chemistry, and liver enzymes negatively in weaned crossbred calves.

Multiscale hierarchical assembly strategy and mechanical prowess in conch shells (Busycon carica).

Seashells are natural body armors with superior mechanical strength and ultra-high toughness compared with their major constituent counterparts. What building blocks and architecture render seashells such mechanical prowess? In this study, micro/nanoscale structural and mechanical characterization of conch shells (Busycon carica) has been carried out. Here we show direct evidence that the previously claimed single-crystal third-order lamellae--the basic building blocks in conch shells are essentially assembled with aragonite nanoparticles of the size ranging from 20 to 45 nm. The nanoparticle-constructed third-order lamellae are not brittle, but ductile. The three-order crossed-lamellar architecture interlocks cracks via crack deflection along the interfaces in a three-dimensional manner, thus confining the damage in a small region. The findings advance the understanding of the mystery of conch shell's mechanical robustness, provide additional design guidelines for developing bioinspired nanomaterials, and lay a constitutive foundation for modeling the deformation behavior of seashells.

Comparative Study of Fire Resistance and Anti-Ageing Properties of Intumescent Fire-Retardant Coatings Reinforced with Conch Shell Bio-Filler.

Conch shell bio-filler (CSBF) was prepared by washing, ultrasonicating, and pulverizing of conch shells and then was applied in waterborne intumescent fire-retardant coatings. The influence of CSBF on fire resistance and anti-ageing properties of intumescent fire-retardant coatings were studied by using different analytical methods. The fire protection and smoke density tests showed that when the mass fraction of CSBF was 3%, the resulting FRC3 coating had the optimum synergistic flame-retardant and smoke-suppression effects concomitant with a flame-spread rating of 10.7, equilibrium backside temperature of 152.4 °C at 900 s, and smoke-density rating value of 10.4%, which were attributed to the establishment of a more dense and stable intumescent char layer against heat and mass transfer. Thermogravimetric analysis indicated that the presence of CSBF increased the thermal stability and char-forming performance of the coatings, and the char residue of FRC3 rose to 34.6% at 800 °C from 28.6% of FRC0 without CSBF. The accelerated ageing test suggested that the incorporation of CSBF reduced the migration and decomposition of the flame retardants and the yellowing, blistering, and powdering phenomenon, thus improving the structural stability of the coating, resulting in better durability of flame retardancy and smoke-suppression performance.

Modern, archaeological, and paleontological DNA analysis of a human-harvested marine gastropod (Strombus pugilis) from Caribbean Panama.

Although protocols exist for the recovery of ancient DNA from land snail and marine bivalve shells, marine conch shells have yet to be studied from a paleogenomic perspective. We first present reference assemblies for both a 623.7 Mbp nuclear genome and a 15.4 kbp mitochondrial genome for Strombus pugilis, the West Indian fighting conch. We next detail a method to extract and sequence DNA from conch shells and apply it to conch from Bocas del Toro, Panama across three time periods: recently-eaten and discarded (n = 3), Late Holocene (984-1258 before present [BP]) archaeological midden (n = 5), and mid-Holocene (5711-7187 BP) paleontological fossil coral reef (n = 5). These results are compared to control DNA extracted from live-caught tissue and fresh shells (n = 5). Using high-throughput sequencing, we were able to obtain S. pugilis nuclear sequence reads from shells across all age periods: up to 92.5 thousand filtered reads per sample in live-caught shell material, 4.57 thousand for modern discarded shells, 12.1 thousand reads for archaeological shells, and 114 reads in paleontological shells. We confirmed authenticity of the ancient DNA recovered from the archaeological and paleontological shells based on 5.7× higher average frequency of deamination-driven misincorporations and 15% shorter average read lengths compared to the modern shells. Reads also mapped to the S. pugilis mitochondrial genome for all but the paleontological shells, with consistent ratios of mitochondrial to nuclear mapped reads across sample types. Our methods can be applied to diverse archaeological sites to facilitate reconstructions of the long-term impacts of human behaviour on mollusc evolutionary biology.

Dynamic self-strengthening of a bio-nanostructured armor - conch shell.

Bio-nanowire structured armors - conch shells, which are often collected as art pieces, possess a special function - an unusual resilience against high speed predatory attacks. Under high-strain-rate compression (strain rate ~103 s-1) conch shells highlight significantly high fracture strength vis-à-vis under quasi-static loading (strain rate ≤ 10-2/s). The dynamic fracture strength reaches a strikingly high value of 600 MPa, 67% enhancement with reference to that of quasi-static loading with the fracture strength 360 MPa. Upon dynamic impact loading, conch shells ingeniously activated a new defense mechanism - intra-lamella fracture, which differs from the inter-lamella fracture damage under quasi-static loading. The lengthy third-order lamellae with a length of hundreds of micrometers were pulverized into rods with the length ranging from 0.4 µm and 2.5 µm upon dynamic loading, whereas the third-order lamellae in the quasi-statically fractured segments maintained the length of hundreds of micrometers. Multiple energy-dissipating mechanisms - intra-lamella fracture, nanoparticle rotation and dislocation enabled nanoparticle deformation in a synergistical fashion contribute to the high strain rate fracture strength of conch shells. This dynamic self-strengthening strategy provides a new guideline for designing dynamically robust materials.

Hierarchically Enhanced Impact Resistance of Bioinspired Composites.

An order of magnitude tougher than nacre, conch shells are known for being one of the toughest body armors in nature. However, the complexity of the conch shell architecture creates a barrier to emulating its cross-lamellar structure in synthetic materials. Here, a 3D biomimetic conch shell prototype is presented, which can replicate the crack arresting mechanisms embedded in the natural architecture. Through an integrated approach combining simulation, additive manufacturing, and drop tower testing, the function of hierarchy in conch shell's multiscale microarchitectures is explicated. The results show that adding the second level of cross-lamellar hierarchy can boost impact performance by 70% and 85% compared to a single-level hierarchy and the stiff constituent, respectively. The overarching mechanism responsible for the impact resistance of conch shell is the generation of pathways for crack deviation, which can be generalized to the design of future protective apparatus such as helmets and body armor.