Chemical extraction of chitin from American lobster (Homarus americanus) shells optimized through response surface methodology.

Chitin extraction from the shells of American lobsters (Homarus americanus) was optimized through the use of response surface methodology (RSM). The demineralization step was optimized to minimize the ash content of shell samples and the deproteination step was optimized to minimize the protein content of the chitin product. At a laboratory scale, one set of optimized conditions for the demineralization step was 7.35 % w/w acetic acid at a 40 mL/g of powdered lobster shell ratio for 15 min; this lowered the ash content from 39.62 % to 0.41 ± 0.08 %. A set of optimized conditions for the deproteination step at a similar scale was 4 % w/w sodium hydroxide at a 43 mL/g demineralized shell ratio heated to 95 °C for 83 min. These conditions were indicated to entirely remove protein from the resultant chitin. Average yields under optimized conditions were 23.43 ± 1.75 % for demineralization and 30.33 ± 0.02 % for deproteination, though a demineralization reaction with larger biomass input had a higher yield at 40.31 %.

Ocean acidification, warming and feeding impacts on biomineralization pathways and shell material properties of Magallana gigas and Mytilus spp.

Molluscs are among the organisms affected by ocean acidification (OA), relying on carbon for shell biomineralization. Metabolic and environmental sourcing are two pathways potentially affected by OA, but the circumstances and patterns by which they are altered are poorly understood. From previous studies, mollusc shells grown under OA appear smaller in size, brittle and thinner, suggesting an important alteration in carbon sequestration. However, supplementary feeding experiments have shown promising results in offsetting the negative consequences of OA on shell growth. Our study compared carbon uptake by δ13C tracing and deposition into mantle tissue and shell layers in Magallana gigas and Mytilus species, two economically valuable and common species. After subjecting the species to 7.7 pH, +2 °C seawater, and enhanced feeding, both species maintain shell growth and metabolic pathways under OA without benefitting from extra feeding, thus, showing effective acclimation to rapid and short-term environmental change. Mytilus spp. increases metabolic carbon into the calcite and environmental sourcing of carbon into the shell aragonite in low pH and high temperature conditions. Low pH affects M. gigas mantle nitrogen isotopes maintaining growth. Calcite biomineralization pathway differs between the two species and suggests species-specific response to OA.

Porous Biphasic Calcium Phosphate Granules from Oyster Shell Promote the Differentiation of Induced Pluripotent Stem Cells.

Oyster shells are rich in calcium, and thus, the potential use of waste shells is in the production of calcium phosphate (CaP) minerals for osteopathic biomedical applications, such as scaffolds for bone regeneration. Implanted scaffolds should stimulate the differentiation of induced pluripotent stem cells (iPSCs) into osteoblasts. In this study, oyster shells were used to produce nano-grade hydroxyapatite (HA) powder by the liquid-phase precipitation. Then, biphasic CaP (BCP) bioceramics with two different phase ratios were obtained by the foaming of HA nanopowders and sintering by two different two-stage heat treatment processes. The different sintering conditions yielded differences in structure and morphology of the BCPs, as determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface area analysis. We then set out to determine which of these materials were most biocompatible, by co-culturing with iPSCs and examining the gene expression in molecular pathways involved in self-renewal and differentiation of iPSCs. We found that sintering for a shorter time at higher temperatures gave higher expression levels of markers for proliferation and (early) differentiation of the osteoblast. The differences in biocompatibility may be related to a more hierarchical pore structure (micropores within macropores) obtained with briefer, high-temperature sintering.

PU14, a Novel Matrix Protein, Participates in Pearl Oyster, Pinctada Fucata, Shell Formation.

Biomineralization is a widespread biological process, involved in the formation of shells, teeth, and bones. Shell matrix proteins have been widely studied for their importance during shell formation. In 2015, our group identified 72 unique shell matrix proteins in Pinctada fucata, among which PU14 is a matrix protein detected in the soluble fraction that solely exists in the prismatic layer. However, the function of PU14 is still unclear. In this study, the full-length cDNA sequence of PU14 was obtained and functional analyses of PU14 protein during shell formation were performed. The deduced protein has a molecular mass of 77.8 kDa and an isoelectric point of 11.34. The primary protein structure contains Gln-rich and random repeat units, which are typical characteristics of matrix protein and indicate its potential function during shell formation. In vivo and in vitro experiments indicated PU14 has prismatic layer functions during shell formation. The tissue expression patterns showed that PU14 was mainly expressed in the mantle tissue, which is consistent with prismatic layer formation. Notching experiments suggested that PU14 responded to repair and regenerate the injured shell. After inhibiting gene expression by injecting PU14-specific double-stranded RNA, the inner surface of the prismatic layer changed significantly and became rougher. Further, in vitro experiments showed that recombinant protein rPU14 impacted calcite crystal morphology. Taken together, characterization and functional analyses of a novel matrix protein, PU14, provide new insights about basic matrix proteins and their functions during shell formation.

Phosphorus Co-Existing in Water: A New Mechanism to Boost Boron Removal by Calcined Oyster Shell Powder.

The removal of boron (B) from water by co-precipitation with hydroxyapatite (HAP) has been extensively studied due to its low cost, ease of use and high efficiency. However, there is no explicit mechanism to express how resolved B was trapped by HAP. Thus, in this work, the process of removing B from water was studied using a low-cost calcium (Ca) precipitation agent derived from used waste oyster shells. The results showed that the removal rate of B in the simulated wastewater by calcined oyster shell (COS) in the presence of phosphorus (P) is up to more than 90%, as opposed to virtually no removal without phosphate. For B removal, the treated water needs to be an alkaline solution with a high pH above 12, where B is removed as [CaB(OH)4]+ but is not molecular. Finally, the synergistic mechanism of co-precipitation between HAP and dissolved B, occlusion co-precipitation, was explained in detail. The proposed method discovered the relationship between Ca, P and B, and was aimed at removing B without secondary pollution through co-precipitation.

The Pleistocene-Holocene aquatic molluscs as indicators of the past ecosystem changes in Transbaikalia (Eastern Siberia, Russia).

Data on the historical change of the Transbaikalian malacofauna in the Neopleistocene and Holocene is presented. Aquatic mollusc shells from archaeological excavations of the ancient settlements dating from the Neolithic period to Medieval and also from a drill hole of the Neopleistocene alluvial deposits were collected. In total eight species of bivalve molluscs from the families Margaritiferidae, Unionidae, Lymnocardiidae, Glycymerididae [marine], and two gastropod species from families Viviparidae and Planorbidae were identified. These species were aged using radiocarbon dating. It was found that the species ranged in age from more than 50.000 to 2.080-1.210 years BP. Five species inhabited the Transbaikal region which are locally extirpated today. Their disjunctive ranges in the past included southern Europe and Western and Eastern Siberia to Transbaikalia and in the east to Far East and Primorye Territory of Russia. A remarkable finding is that of the bivalve genus Monodacna, which was found very far from its native range, the Ponto-Caspian region. The time of existence and extirpation of the thermophilic species of genera Monodacna, Planorbis, Lanceolaria and Amuropaludina corresponds to cycles of the warming and cooling in Pleistocene and Holocene according to regional climate chronological scales. These species can be used as palaeoclimate indicators. Change of the regional malacofaunal species composition is connected with the natural climatochron cycles in the Pleistocene and Holocene resulting in evidence for succession. In the course of this succession, these stenothermal species became extirpated on a regional level, decreasing their global ranges.

Calcarea carbonica treatment rescues lipopolysaccharide-induced inflammatory response in human mononuclear cells via downregulation of inducible cyclooxygenase pathway.

OBJECTIVE: Prolonged use of nonsteroidal anti-inflammatory drugs is associated with severe side effects and toxicity. Therefore, we studied the anti-inflammatory role of Calcarea carbonica which had minimal toxicity at the low doses. METHODS: THP-1 human mononuclear cells were treated with C. carbonica to evaluate the 50% cytotoxicity concentration (CC50) and 50% effective concentration (EC50). Cell survival was evaluated in lipopolysaccharide-stimulated C. carbonica-treated cells. Nitric oxide (NO) and tumor necrosis factor-α (TNF-α) were measured to evaluate the anti-inflammatory activity of C. carbonica. Cyclooxygenase-2 (COX-2) protein expression was determined by Western blotting analysis, and the interaction of C. carbonica with the COX-2 protein was evaluated using molecular docking simulation. RESULTS: The CC50 and EC50 of C. carbonica were found to be 43.26 and 11.99 µg/mL, respectively. The cell survival assay showed a 1.192-fold (P = 0.0129), 1.443-fold (P = 0.0009) and 1.605-fold (P = 0.0004) increase in cell survival at 24, 48 and 72 h after initiating C. carbonica treatment, respectively. C. carbonica-treated cells showed a reduction in NO levels by 2.355 folds (P = 0.0001), 2.181 folds (P = 0.0001) and 2.071 folds (P = 0.0001) at 24, 48 and 72 h, respectively. The treated cells also showed a reduction in TNF-α levels by 1.395 folds (P = 0.0013), 1.541 folds (P = 0.0005) and 1.550 folds (P = 0.0005) at 24, 48 and 72 h, respectively. In addition, a 1.193-fold reduction (P = 0.0126) in COX-2 protein expression was found in C. carbonica-treated cells. The molecular docking showed interaction of C. carbonica with the phenylalanine 367 residue present in active site of Cox-2. CONCLUSION: C. carbonica exhibited anti-inflammatory properties in lipopolysaccharide-stimulated cells by significantly reducing NO production and TNF-α level through downregulation of the COX-2 protein. This effect is probably mediated through interaction of C. carbonica with the phenylalanine 367 residue present in active site of Cox-2.

Thermal stable characteristics of acid- and pepsin-soluble collagens from the carapace tissue of Chinese soft-shelled turtle (Pelodiscus sinensis).

The carapace from the Chinese soft-shelled turtle (Pelodiscus sinensis) is used as a traditional Chinese medicine. Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from turtle carapace were isolated and characterized to screen novel collagen material in this study. Yields of 1.0% and 2.8% were obtained for ASC and PSC which contained glycine as the major amino acid and had high imino acid content. Both collagens had maximum ultraviolet absorption peaks of 220 nm. SDS-PAGE revealed that the structure of both collagens was similar, belonging to type I collagen. Relative viscosities of collagens were decreased as the temperature increased. Collagens showed minimum solubility at pH 8 and maximum solubility at a salt concentration of 3%. The denaturation temperature (Td) of PSC was higher whereas the melting temperature was lower than that of ASC. Both ASC and PSC appeared to be spongy like microstructure with fibrillar pores shown by scanning electron microscopy. The results suggest that collagens isolated from turtle carapace has high thermal stability with potential uses as new substitute for mammalian collagen in medicinal, food or biomaterial fields. However, their biological or pharmacological activities are needed to be further studied.

Bioshell calcium oxide (BiSCaO) for cleansing and healing Pseudomonas aeruginosa-infected wounds in hairless rats.

BACKGROUND: Scallop shell powder is called bioshell calcium oxide (BiSCaO), which is known to possess deodorizing properties and broad antimicrobial activity against various pathogenic microbes, including viruses, bacteria, spores, and fungi. OBJECTIVE: This study aims to investigate the applications of BiSCaO suspension cleansing in clinical situations, for instance for the prevention and treatment of infections in chronic wounds in healing-impaired patients, without delaying wound healing. METHODS: The bactericidal activities of 1000 ppm BiSCaO suspension; 500 ppm hypochlorous acid; 1000 ppm povidone iodine; and saline were compared to evaluate in vivo disinfection and healing of Pseudomonas aeruginosa-infected wounds in hairless rats. RESULTS: Cleansing of the infected wounds with BiSCaO suspension daily for 3 days significantly enhanced wound healing and reduced the in vivo bacterial counts, in comparison to hypochlorous acid, povidone iodine, and saline. Furthermore, histological examinations showed significantly advanced granulation tissue and capillary formation in the wounds cleansed with BiSCaO suspension than in those cleansed with the other solutions. CONCLUSIONS: This study suggested that the possibility of using BiSCaO suspension as a disinfectant for infected wounds and limiting disinfection to 3 days may be sufficient to avoid the negative effects on wound repair.

Determination of four nitrofuran metabolites in gelatin Chinese medicine using dispersive solid phase extraction and pass-through solid phase extraction coupled to ultra high performance liquid chromatography-tandem mass spectrometry.

This study established a validated analytical method for the first time on the determination of nitrofuran metabolites, including semicarbazide (SEM), 1-aminohydantoin (AHD), 3-amino-2-oxazolidinone (AOZ) and 3-amino-5-morpholinomethyl-2-oxazolinone (AMOZ) in gelatin Chinese medicine. A C18 column with the mobile phase consisting of acetonitrile and 5 mmol/L ammonium acetate in water was used to separate these nitrofuran metabolites. The limit of detection of SEM, AHD, AOZ and AMOZ were found to be 0.2 µg/kg, 0.3 µg/kg, 0.2 µg/kg and 0.2 µg/kg, whereas their limit of quantification were 0.6 µg/kg, 0.8 µg/kg, 0.6 µg/kg and 0.5 µg/kg. These nitrofuran metabolites exhibited a good linear standard curve (regression coefficients above 0.99) with a concentration range of 2 µg/L to 100 µg/L. Regarding extraction procedure, gelatin Chinese medicine was pre-treated with pepsin and then extracted using 5% formic acid (v/v) in acetonitrile. The resultant extract was purified through dispersive solid phase extraction using 1000 mg anhydrous sodium sulfate, 300 mg octadecyl carbon silica gel sorbent absorbent and 500 mg ethylenediamine-N-propyl carbon silica gel absorbent, and then further purified on Oasis PRiME HLB cartridges. The matrix effect was effectively eliminated after the clean-up procedure as confirmed by comparing the ratio of standard curves prepared by standards dissolved in both matrix solvent and 5 mmol/L ammonium acetate in water: acetonitrile (95:5, v/v). The recoveries of these nitrofuran metabolites under the 1 µg/kg, 2 µg/kg and 10 µg/kg spiking levels were between 77.4% and 95.6%. These metabolites after the extraction were stable at 4 °C for 24 h. The validated method was used to analyze the residue level of these nitrofuran metabolites in 25 gelatin Chinese medicines. Results showed that only one Colla Corii Asini sample contained SEM (2.52 µg/kg) and AOZ (6.27 µg/kg), whereas one Testudinis Carapacis et Plastri sample had SEM (1.27 µg/kg) and AMOZ (9.53 µg/kg).

A Classification Method of Oracle Materials Based on Local Convolutional Neural Network Framework.

The classification of materials of oracle bone is one of the most basic aspects for oracle bone morphology. However, the classification method depending on experts' experience requires long-term learning and accumulation for professional knowledge. This article presents a multiregional convolutional neural network to classify the rubbings of oracle bones. First, we detected the "shield grain" and "tooth grain" on the oracle bone rubbings, then complete the division of multiple areas on an image of oracle bone. Second, the convolutional neural network is used to extract the features of each region and we complete the fusion of multiple local features. Finally, the classification of tortoise shell and animal bone was realized. Utilizing the image of oracle bone provided by experts, we conducted an experiment; the result show our method has better classification accuracy. It has made contributions to the progress of the study of oracle bone morphology.

Bioavailability and prebiotic potential of Carapax Trionycis, a waste from soft-shelled turtle processing.

BACKGROUND: Carapax Trionycis is the shell of the soft-shelled turtle. It is rich in minerals, amino acid, peptides, and other nutrients. Current processing and consumption of soft-shelled turtle leads to the waste of huge quantities of Carapax Trionycis in the form of spent materials. In this study, the bioavailability, prebiotic activity, and physicochemical properties of Carapax Trionycis using different processing methods were investigated. The vinegar-quenched Carapax Trionycis (V-CT), fine powders (D0.18, D0.10), and superfine powders (D0.05, D0.025) of Carapax Trionycis were prepared by the vinegar-quenching method, common grinding, and the superfine grinding method. RESULTS: The average particle sizes of D0.18, D0.10, D0.05, and D0.025 were 147.82, 77.35, 36.65, and 2.24 µm, respectively. Superfine grinding changed the surface morphology of Carapax Trionycis and promoted the release of active ingredients. D0.025 had the highest polypeptide (8.15%), polysaccharide (1.21%), total free amino acid (232.36 mg 100 g-1 ) and water-soluble extract content (10.74%), and showed the highest calcium release rate (55.64%) after in vitro digestion. The apparent permeability (PAPP ) of the resulting Carapax Trionycis samples in the dialysis tubing model and the everted intestinal sac model increased significantly with the decrease in the Carapax Trionycis particle sizes. Furthermore, the five Carapax Trionycis samples significantly stimulated the growth of the tested probiotics and increased lactic acids production after 48 h fermentation compared to the control. The Carapax Trionycis powder prepared by superfine grinding displayed better prebiotic activity than other samples as it significantly induced a greater proliferation of probiotic bacteria and higher production of lactic acid, as well as greater release of free calcium. CONCLUSIONS: The results showed that Carapax Trionycis superfine powder D0.025 had the highest active ingredient content, calcium bioavailability, and prebiotic activity. Our approach of developing Carapax Trionycis superfine powder as natural calcium supplement or potential prebiotic would therefore broaden the scope of soft-shelled turtle processing waste utilization in an eco-friendly, cost-effective, and sustainable approach in the future. © 2020 Society of Chemical Industry.

Purification, characterization and antibacterial activities of red color-related protein found in the shell of kuruma shrimp, Marsupenaeus japonicus.

The well-known red color change plays a significant role in consumer acceptability of crustacean species. In this study, we described the purification of the red color-related protein named MjRCP75 from the shell of Marsupenaeus japonicus. It was a homogeneous monomer with molecular mass of 75 kDa and rich in α-helix conformation. The α-helix content decreased within the increasing of heating temperature and was transformed dominantly to ß types. Identification and structural analysis revealed that MjRCP75 belonged to hemocyanin family. The released pigment from heated MjRCP75 showed a λmax at 483 nm in acetone. MjRCP75 showed clearly antibacterial activity against Escherichia coli, Staphylococcus aureus, and Vibrio parahaemolyticus. These findings identify MjRCP75 as the red color-related protein in M. japonicus shell and reveal its involvement in antibacterial activities.

Quantifying spatial variability in shell midden formation in the Farasan Islands, Saudi Arabia.

During the past decade, over 3000 shell middens or shell matrix deposits have been discovered on the Farasan Islands in the southern Red Sea, dating to the period c. 7,360 to 4,700 years ago. Many of the sites are distributed along a palaeoshoreline which is now 2-3 m above present sea level. Others form clusters with some sites on the shoreline and others located inland over distances of c. 30 m to 1 km. We refer to these inland sites as 'post-shore' sites. Following Meehan, who observed a similar spatial separation in shell deposition in her ethnographic study of Anbarra shellgathering in the Northern Territory of Australia, we hypothesise that the shoreline sites are specialised sites for the processing or immediate consumption of shell food, and the post-shore sites are habitation sites used for a variety of activities. We test this proposition through a systematic analysis of 55 radiocarbon dates and measurement of shell quantities from the excavation of 15 shell matrix sites in a variety of locations including shoreline and post-shore sites. Our results demonstrate large differences in rates of shell accumulation between these two types of sites and selective removal of shoreline sites by changes in sea level. We also discuss the wider implications for understanding the differential preservation and visibility of shell-matrix deposits in coastal settings in other parts of the world extending back into the later Pleistocene in association with periods of lowersea level. Our results highlight the importance of taphonomic factors of post-depositional degradation and destruction, rates of shell accumulation, the influence on site location of factors other than shell food supply, and the relative distance of deposits from their nearest palaeoshorelines as key variables in the interpretation of shell quantities. Failure to take these variables into account when investigating shells and shell-matrix deposits in late Pleistocene and early Holocene contexts is likely to compromise interpretations of the role and significance of shell food in human evolutionary and socio-cultural development.

Crab Shell Extract Improves Sperm Parameters and Antioxidant Status in Testes of Diabetic Rats.

Crab shell (CS), which contains antioxidant compounds, has been used as a promising nutritional and medical compound in traditional medicine. Oxidative stress plays a critical role in the development of diabetes. This study aims to investigate the effects of CS extract (CSE) on sperm parameters, antioxidant status, and histopathology changes of testes in diabetic rats. In this experimental study, 40 Wistar male rats were investigated in five groups (n = 8/group): diabetic rats treated with different CS concentrations (i.e., 100, 200, and 400 mg/kg), diabetic group, and nondiabetic control. To induce diabetes, a single dose (60 mg/kg) of streptozotocin (STZ) was injected intraperitoneally; three days later, treatment with CSE was begun and conducted for 14 days. The fasting blood glucose, testes weight, and viability, number, and motility of sperm were assessed. In addition, the levels of ferric reducing antioxidant power (FRAP) and nitric oxide (NO) were estimated in the testes. Testes were examined using histological analysis. The results of this study revealed that sperm number, motility, and serum testosterone levels of CSE-treated diabetic rats increased significantly (p = .000) compared with the untreated diabetic group in a dose-depended manner while the number of immotile sperm decreased significantly (p = .017). CS also reduced the testicular level of nitric oxide and fasting blood glucose; however, it led to significant growth in the FRAP levels of testes (p = .002). Our results suggest that CSE improves sperm parameters and protects the testicular tissue against the oxidative stress damage induced by diabetes.

Controlling risks of P water pollution by sorption on soils, pyritic material, granitic material, and different by-products: effects of pH and incubation time.

Batch experiments were used to test P sorbent potential of soil samples, pyritic and granitic materials, mussel shell, mussel shell ash, sawdust, and slate waste fines for different pH and incubation times. Maximum P sorption varied in a wide range of pH: < 4 for pyritic material, 4-6 for forest soil, > 5 for slate fines, > 6 for shell ash, and pH 6-8 for mussel shell. P sorption was rapid (< 24 h) for forest soil, shell ash, pyritic material, and fine shell. On the opposite side, it was clearly slower for vineyard soil, granitic material, slate fines, pine sawdust, and coarse shell, with increased P sorption even 1 month later. For any incubation time, P sorption was > 90% in shell ash, whereas forest soil, pyritic material, and fine shell showed sorption rates approaching 100% within 24 h of incubation. These results could be useful to manage and/or recycle the sorbents tested when focusing on P immobilization or removal, in circumstances where pH changes and where contact time may vary from hours to days, thus aiding to diminish P pollution and subsequent eutrophication risks, promoting conservation and sustainability.

Recovery of phosphorus rich krill shell biowaste for uranium immobilization: A study of sorption behavior, surface reaction, and phase transformation.

Increased generation of shrimp shell from exploitation of krill results in emerging biowaste pollution, in addition, uranium pollution has drawn public concern due to the rapid development of nuclear power, uranium mining, and nuclear fuel processing. In this study, krill shells were recovered and used as a potential natural biosorbent for uranium immobilization, thereby enabling both uranium decontamination and krill shell reutilization. Interaction of uranium with krill shell surface and their transformation were investigated by using batch sorption experiments, scanning electron microscopy, and transmission electron microscopy. Krill shell had high uranium sorption ability. Uranium was transformed into a nano-scale precipitate. The mapping of phosphorus and uranium was related to the nano-scale precipitate, indicating that sorption of uranium was dependent on phosphorus. Surface chemisorption between phosphate in krill shell and uranium as well as the formation of the nano-scale precipitate were interpreted as the mechanism of uranium immobilization. Thus, natural krill shell waste has potential for extensive use as a promising and cost-effective sorbent for uranium immobilization and krill shell reutilization.

Versatile acid base sustainable solvent for fast extraction of various molecular weight chitin from lobster shell.

Deep eutectic solvent (DES) prepared from choline chloride and four organic acid were evaluated for the extraction of chitin from lobster shell. It was found that the purity of chitins extracted with DESs was related to acid used. Purity of chitin extracted with choline chloride-malonic acid was the highest. Chitins extracted through DES treatment results in various molecular weight, which is associated with type of acid and temperature used during the treatment. For instance, chitin produced by malonic acid at 50 °C and 100 °C results in molecular weight of 312 KDa and 199 KDa respectively, whereas it extracted with malic acid at 100 °C results in 91 KDa. The physicochemical properties of chitins were characterized by FTIR, XRD, TG and SEM. Moreover, the CaCO3 was successfully converted into levulinic acid calcium salt which could be used as calcium supplement.

One-pot production of chitin with high purity from lobster shells using choline chloride-malonic acid deep eutectic solvent.

For the first time in this study, chitin was solely extracted from lobster shells through a fast, easy and eco-friendly method using deep eutectic solvents (DESs), consisting of mixtures of choline chloride-thiourea (CCT), choline chloride-urea (CCU), choline chloride-glycerol (CCG) and choline chloride-malonic acid (CCMA). The physiochemical properties of the isolated chitins were compared with those of the chemically prepared one and commercial one from shrimp shells. Results showed that CCT, CCU and CCG DESs had no important effect on the elimination of proteins and minerals, while chitin obtained by CCMA DES showed a high purity. The yield (20.63±3.30%) of chitin isolated by CCMA DES was higher than that (16.53±2.35%) of the chemically prepared chitin. The chitin obtained by CCMA DES could be divided into two parts with different crystallinity (67.2% and 80.6%), which also had different thermal stability. Chitin from lobster shells showed porous structure, which is expected to be used for adsorption materials and tissue engineering.

Temporal variability in shell mound formation at Albatross Bay, northern Australia.

We report the results of 212 radiocarbon determinations from the archaeological excavation of 70 shell mound deposits in the Wathayn region of Albatross Bay, Australia. This is an intensive study of a closely co-located group of mounds within a geographically restricted area in a wider region where many more shell mounds have been reported. Valves from the bivalve Tegillarca granosa (Linnaeus, 1758) were dated. The dates obtained are used to calculate rates of accumulation for the shell mound deposits. These demonstrate highly variable rates of accumulation both within and between mounds. We assess these results in relation to likely mechanisms of shell deposition and show that rates of deposition are affected by time-dependent processes both during the accumulation of shell deposits and during their subsequent deformation. This complicates the interpretation of the rates at which shell mound deposits appear to have accumulated. At Wathayn, there is little temporal or spatial consistency in the rates at which mounds accumulated. Comparisons between the Wathayn results and those obtained from shell deposits elsewhere, both in the wider Albatross Bay region and worldwide, suggest the need for caution when deriving behavioural inferences from shell mound deposition rates, and the need for more comprehensive sampling of individual mounds and groups of mounds.