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1
Ma, Xueping, and Jed Day. "Revision of selected North American and Eurasian Late Devonian (Frasnian) species of Cyrtospirifer and Regelia (Brachiopoda)." Journal of Paleontology 77, no. 2 (March 2003): 267–92. http://dx.doi.org/10.1017/s0022336000043638.
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Study of the shell features of Givetian and Frasnian spiriferid brachiopods attributed to the genus Cyrtospirifer shows that the type species C. verneuili has micro-ornament consisting of fine concentric growth lines, radial capillae, with microspines arising from some capillae, spine bases appear to extend into the primary shell layer. Its dorsal interior features a pseudoseptum supporting the cardinalia. Micro-ornament of Cyrtospirifer varies widely and is a useful criterion for characterization of species of the genus. Most Frasnian species retained in the genus have micropustulate shells. Two late Givetian and Frasnian phylogenetic species groups of Cyrtospirifer are recognized based on similarities of shell form and external and internal shell features. Species of the verneuilisyringothyriformis group have transverse alate shells, and are the most abundant and widespread group in Frasnian deposits worldwide. The verneuiliformis group includes the oldest known species of Cyrtospirifer with narrow hinges and more inflated ventral valves where shell width is close to or equal to length. The oldest Cyrtospirifer originated in western Europe during the late Givetian, and subsequently migrated at different times during the Frasnian into other shelf areas of Eurasia, North America and China. The initial migration of Cyrtospirifer into tropical and subtropical shelf settings in North America coincided with the middle Frasnian eustatic sea level rise of Devonian Transgressive-Regressive (T-R) cycle IIc of Johnson and others. A second late Frasnian dispersal from western Canada to subtropical carbonate and clastic shelves in the southwestern and central U.S. coincided with the initial sea level rise of T-R cycle IId of Johnson and others. The Frasnian species Cyrtospirifer glaucus Crickmay, 1952a (middle Frasnian of western Canada) is the type species for Regelia Crickmay, 1952b, and is considered a valid genus, and is not a synonym of C. chemungensis (Conrad, 1842) as previously interpreted by some authors. Regelia differs from Cyrtospirifer in the absence of a delthyrial plate, complete in-filling of the delthyrial cavity by secondary shell material, its simpler rod-like teeth, and its fewer medial sinal shell plications. Species of Regelia are restricted to the middle to late Frasnian of North America.
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Chu, You-Hua. "Multiple Shell Planetary Nebulae." Symposium - International Astronomical Union 131 (1989): 105–16. http://dx.doi.org/10.1017/s0074180900137696.
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It has been shown in several independent investigations that the multiple-shell phenomenon is prevalent in planetary nebulae. Despite the common classification, the multiple shell planetary nebulae are a heterogeneous group of objects, as testified by the wide variety of their morphologies and physical structures. There are two types of double-shell structures that are seen frequently: one has an inner shell expanding supersonically into a faint, subsonically expanding halo, and the other has a bright attached envelope co-expanding with the inner shell. The physical structures and relative elemental abundances in the shells are reviewed, and their possible formation mechanisms are discussed.
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Buddawong, Tiranan, Somluk Asuvapongpatana, Chanyatip Suwannasing, Valainipha Habuddha, Chompoonut Sukonset, Chanyarak Sombutkayasith, Carmel McDougall, and Wattana Weerachatyanukul. "Calcineurin subunit B is involved in shell regeneration in Haliotis diversicolor." PeerJ 9 (January 12, 2021): e10662. http://dx.doi.org/10.7717/peerj.10662.
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Abalone shells are mainly composed of two major polymorphs of CaCO3 that are distributed in different layers of the shell. The process of shell biomineralization is controlled by genes and proteins expressed within the mantle epithelium. In this present paper, we conducted a shell regeneration experiment to study the role of HcCNA and HcCNB (individual subunits of calcineurin) in shell biomineralization in H. diversicolor. The results of qPCR showed that HcCNB is upregulated to a greater extent than HcCNA in the mantle after shell notching. In vivo study of the effects of rHcCNB injection showed a significantly higher percentage of regenerated shell length, but not area, in the injected group compared to the control group. In addition, SEM observation of the inner surface of the regenerated shells revealed three different zones including prismatic, nacreous, and a distinct transition zone. Changes in the crystal organization and ultrastructure are clearly evident in these three zones, particularly after 3 weeks of rHcCNB administration. We hypothesize that this is due to faster biomineralization rates in the rHcCNB treated group. Taken together, our results demonstrate that HcCNB participates in shell regeneration in H. diversicolor. As calcineurin subunits have also been implicated in shell formation in bivalves, these findings suggest that calcineurin subunits may play important roles in biomineralization in all conchiferans.
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Kutzner, M., C. Tidwell, S. E. Vance, and V. Radojević. "Inner-shell photoionization of group-IIBatoms." Physical Review A 49, no. 1 (January 1, 1994): 300–309. http://dx.doi.org/10.1103/physreva.49.300.
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Davies, David J., and Molly F. Miller. "Paleocommunity information retrieval vs. shell accumulation mode in Paleozoic carbonates: examples from the Lebanon Limestone (Middle Ordovician), Tennessee, U.S.A." Paleontological Society Special Publications 6 (1992): 81. http://dx.doi.org/10.1017/s2475262200006419.
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Compared to their terrigenous counterparts, carbonate shell accumulations have until recently been relatively little studied to determine either descriptive or genetic classifications of shell bed types, the preservation potential of each type, or their relative ability to preserve community-level information. A partial classification of Paleozoic carbonate shell-rich soft sediment accumulations is proposed using sedimentation patterns in the Lebanon limestone of the Stones River Group. Paleoecological information preserved therein is then contrasted by shell bed type. The Lebanon represents typical Ordovician shallow to moderate subtidal carbonate shelf deposits in outcrops flanking the Nashville Dome and peritidal deposits in the Sequatchie Anticline of Eastern Tennessee; shell beds alternate with shell poor sediments (micrites, wackestones and diagenetically enhanced dolomites and clay-rich partings).None of the analyzed shell beds was strictly biological in origin; most are sedimentological although >10% are combined sedimentological/diagenetic. While the majority are single simple shell beds, >20% are amalgamated. All are thin (1 shell to 15 cm) stringers that pinch and swell showing poor lateral continuity (outcrop scale, tens to hundreds of meters) likely enhanced by burial dissolution. These shell beds differ greatly in fabric (packing/sorting), clast composition, taphonomic signature, and intensity of time averaging; thus community information retrieval is biased in predictable patterns. Virtually no shell beds show common shell dissolution or encrustation from long-term sediment surface exposure or hardground formation. Five major categories of accumulation are herein proposed using a DESCRIPTIVE, non-genetic terminology modified from previous works of DJD, as well as a Genetic interpretation for each. These are easily distinguished in the field and are also discriminated by Q-mode cluster analysis.Categories include, in decreasing frequency of occurrence: 1. SHELL GRAVELS; Storm/“event” beds: Sharp bases; poorly sorted coarse basal bioclasts and/or intraclasts, often with no preferred orientation; clasts fine upward to comminuted shell material and micrite. Horizontal platy brachiopods often cap the beds. High diversity and a wide range in shell alteration is represented, from whole unaltered brachiopods to minor abraded fragments, indicating extreme time averaging and poor resolution of short-term community dynamics. 2. COMMINUTED SHELLY LS; Current/ripple concentrations: Small tidal channel fill and discrete ripple trough accumulations are composed of cross-stratified bioclastic deposits with local concentrations of rip-ups. Beds are not graded; typically clasts are abraded, rounded and concordant with cross-beds. Intense time averaging and mixing of discrete communities is inferred due to continual reworking in these background deposits. 3. SHELL/CEMENT LS; Early cementation beds: Intense early diagenetic alteration is inferred due to red discoloration and rapid intergranular cementation; some beds show diagenetic micritic rinds. Beds may be brecciated and show deep burial stylolitization cutting bioclasts and cement. They may represent zones of preferred early cementation rather than a change in shell accumulation rate. Many shells from some beds show little postmortem alteration; these units may preserve much of the original community structure. 4. DENSE SHELL PAVEMENTS; Subtidal surficial pavements: Single layers of shells, commonly concave down, overlie mudstones/wackestones with no basal erosion. No obrution deposits were noted. Bioclasts are typically disarticulated and reoriented, but are not substantially abraded, broken, or dissolved. Diversity is low. Only minor temporal and lateral community mixing with small environmental fluctuation is indicated. 5. VERTICALLY IMBRICATE SHELLY LS; High energy beach zones: Platy whole and major fragments of brachiopods are deposited in low diversity, high angle imbricate beds. Less postmortem reworking and time averaging is evident compared to types 1 and 2.Thus, the most common (physically reworked) shell bed types show the most intense loss of short-term paleocommunity information. There are surprisingly few insitu community pavements or obligate long-term accumulations. This pattern differs from some described Ordovician carbonates, which may contain common community beds or hardgrounds/hiatal accumulations. This implies a relatively low rate of net sediment accumulation on a shallow, periodically wave swept shelf, and no major flooding surfaces or other indications of significant sea level change. Delineation of the sequence stratigraphic position of these carbonates is enhanced from this type of integrated community/biostratinomic analysis.
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Jiménez-Berrocoso, Álvaro, Eduardo B. Olivero, and Javier Elorza. "New petrographic and geochemical insights on diagenesis and palaeoenvironmental stress in Late Cretaceous inoceramid shells from the James Ross Basin, Antarctica." Antarctic Science 18, no. 3 (August 24, 2006): 357–76. http://dx.doi.org/10.1017/s0954102006000411.
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New petrographic and geochemical insights from inoceramid bivalve shells of lower Campanian (Marambio Group, James Ross Basin, Antarctica) show that they suffered significant palaeoenvironmental stress just before their disappearance in the southern high latitudes. Inoceramid data have mainly been derived from shell fragments of the large form Antarcticeramus rabotensis Crame & Luther, collected at stratigraphical levels marking the early disappearance of inoceramids in the James Ross Basin (10 m.y. before the Cretaceous/Tertiary boundary in Antarctica). Cathodoluminescence studies and minor and trace element intra-shell variations in A. rabotensis shells, along with their whole shell geochemistry (major, minor, and trace elements, including REE), have revealed evidence of only weak diagenesis but significant palaeoenvironmental stress. The most relevant evidence of such adverse palaeoenvironmental conditions in A. rabotensis shells is reflected by marked growth interruptions in the normal shell layering, including the occurrence of a previously undetected inner aragonitic nacreous layer formed of alternating aragonitic and calcitic sublayers. The weak diagenesis produced characteristic geochemical intra-shell variations, which have subsequently been detected in the inoceramid shell microstructure, especially in the inner aragonitic nacreous layer.
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Butler, Aodhán D., Michael Streng, Lars E. Holmer, and Loren E. Babcock. "Exceptionally preserved Mickwitzia from the Indian Springs Lagerstätte (Cambrian Stage 3), Nevada." Journal of Paleontology 89, no. 6 (November 2015): 933–55. http://dx.doi.org/10.1017/jpa.2016.8.
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AbstractExceptionally preserved specimens of the Cambrian stem-group brachiopod Mickwitzia occidens Walcott, 1908 are described in detail from the Indian Springs Lagerstätte in Nevada, USA. Shell structure and preserved mantle setae from these specimens reveal a variable diagenetic (taphonomic) history and provide insight into the phylogenetic position of mickwitziids. Morphologic and morphometric comparison to M. monilifera (Linnarsson, 1869) from Sweden and M. muralensis Walcott, 1913 from British Columbia, Canada reveals clear species-level distinctions. Scanning electron microscopic analysis allows revision of the generic diagnosis. The Mickwitzia shell is characterized by the presence of inwardly pointing phosphatic cones and tangential setae-bearing tubes. The inwardly pointing cone structures are not consistent with setal bearing structures as previously thought, but rather represent endopunctae-like structures. Acrotretid-like shell structures and shell-penetrating setae in M. occidens strengthen the previously proposed close relationship between stem-group brachiopods and tommotiids, a group of small shelly fossils.
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Qian, Li Peng, Du Yuan, Guang Shun Yi, and Gan Moog Chow. "Critical shell thickness and emission enhancement of NaYF4:Yb,Er/NaYF4/silica core/shell/shell nanoparticles." Journal of Materials Research 24, no. 12 (December 2009): 3559–68. http://dx.doi.org/10.1557/jmr.2009.0432.
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Amorphous silica shells, used for functionalization of inorganic nanoparticles in bioapplications, were coated on chemically synthesized NaYF4:Yb,Er upconversion fluorescent nanoparticles via a reverse microemulsion method by using dual surfactants of polyoxyethylene (5) nonylphenylether and 1-hexanol, and tetraethyl orthosilicate as precursor. NaYF4:Yb,Er nanoparticles were equiaxed with a particle size of 11.1 ± 1.3 nm. The thickness of silica shell was ∼8 nm. NaYF4:Yb,Er/silica core/shell nanoparticles were well dispersed in solvents such as ethanol and deionized water. The emission intensities of NaYF4:Yb,Er/silica core/shell nanoparticles remained the same as that of uncoated nanoparticles after surface functionalization with an amine group using (3-aminopropyl)-trimethoxysilan. Silica, although providing a good barrier to the nonradiative relaxation between the upconversion nanoparticles and the environments, did not enhance the emission intensity of upconversion nanoparticles. To increase the emission intensity of NaYF4:Yb,Er/silica core/shell nanoparticles, an undoped NaYF4 shell (∼3-nm thick) was deposited on the upconversion nanoparticles before the silica coating. The total emission intensity of NaYF4:Yb,Er/NaYF4/silica core/shell/shell nanoparticles increased by 15 times compared to that without the intermediate NaYF4 shell. The critical shell thickness of NaYF4 was ∼3 nm, beyond which no further emission intensity enhancement was observed.
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Kehrwald, Natalie M., William D. McCoy, Jeanne Thibeault, Stephen J. Burns, and Eric A. Oches. "Paleoclimatic implications of the spatial patterns of modern and LGM European land-snail shell δ18O." Quaternary Research 74, no. 1 (July 2010): 166–76. http://dx.doi.org/10.1016/j.yqres.2010.03.001.
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AbstractThe oxygen isotopic composition of land-snail shells may provide insight into the source region and trajectory of precipitation. Last glacial maximum (LGM) gastropod shells were sampled from loess from Belgium to Serbia and modern land-snail shells both record δ18O values between 0‰ and − 5‰. There are significant differences in mean fossil shell δ18O between sites but not among genera at a single location. Therefore, we group δ18O values from different genera together to map the spatial distribution of δ18O in shell carbonate. Shell δ18O values reflect the spatial variation in the isotopic composition of precipitation and incorporate the snails' preferential sampling of precipitation during the warm season. Modern shell δ18O decreases in Europe along a N–S gradient from the North Sea inland toward the Alps. Modern observed data of isotopes in precipitation (GNIP) demonstrate a similar trend for low-altitude sites. LGM shell δ18O data show a different gradient with δ18O declining toward the ENE, implying a mid-Atlantic source due to increased sea ice and a possible southern displacement of the westerly jet stream. Balkan LGM samples show the influence of a Mediterranean source, with δ18O values decreasing northward.
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Mudaim, Sarifah, Sahrul Hidayat, and Risdiana. "Effect of Heating Temperature on the Chemical Structure and of Conductivity Carbon from Candlenut Shells (Aleurites Moluccana)." Materials Science Forum 1028 (April 2021): 302–7. http://dx.doi.org/10.4028/www.scientific.net/msf.1028.302.
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Candlenut Shells is one of the many commodities growing in Indonesia and experiencing rapid progress production development. The shell of candlenut has good characteristic that allow it to be used as carbon. activated carbon is one of material that can be applied for various application. In this paper, we reported the synthesis of activated carbon from candlenut shell in order to get high quality of carbon by controlling the heating temperature in synthesis. Variation of heating temperature in to produce carbon were 300, 400, 500, 600 and 700 °C . FTIR Spectroscopy was carried out to determine the functional groups on the carbon from candlenut shells. FTIR analysis during the carbonization process was indicated the change in functional group of chemical structure from the candlenut shell, which is shown by decreasing the absorption spectrum of some functional groups of the candlenut shell after the carbonization process. The carbonization process has formed aromatic C = C and reduction functional group OH (aromatic compounds), C-H (aromatic ring), C-O (vibration ether structure) dan C=O (Ester compounds). And results of carbonization of candlenut shells at various temperatures have an electrical conductivity value that increases with increasing carbonization temperature. The carbonization temperature that is raised to 700 °C causes carbon to be more conductive with an increased electrical conductivity value. XRF characterization results also showed that in addition to carbon elements in the cundlenut shells, other elements were also found such as calcium, magnesium, aluminum, potassium, strontium, manganese, iron and zinc. Ca and Mg are the largest content besides carbon.
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Liu, Xiao, Yufei Jiang, Lawrence Wu, and Dinghao Wu. "Natural Shell." International Journal of People-Oriented Programming 5, no. 1 (January 2016): 1–18. http://dx.doi.org/10.4018/ijpop.2016010101.
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Scripting is a widely-used way to automate the execution of tasks. Despite the popularity of scripting, it remains difficult to use for both beginners and experts: because of the cryptic commands for the first group, and incompatible syntaxes across different systems, for the latter group. The authors introduce Natural Shell, an assistant for enabling end-users to generate commands and scripts for various purposes. Natural Shell automatically synthesizes scripts for different shell systems based on natural language descriptions. By interacting with Natural Shell, new users can learn the basics of scripting languages without the obstacles from the incomprehensible syntaxes. On the other hand, the authors' tool frees more advanced users from manuals when they switch shell systems. The authors have developed a prototype system and demonstrate its effectiveness with a benchmark of 50 examples of popular shell commands collected from online forums. In addition, the authors analyzed the usage of Natural Shell in a lab study that involves 10 participants with different scripting skill levels. Natural Shell effectively assists the users to generate commands in assigned syntaxes and greatly streamlines their learning and using experience.
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Köhler, Frank, and Vince Kessner. "Mitochondrial and morphological differentiation in a previously unrecognized radiation of the land snail genus Parachloritis Ehrmann, 1912 on Timor (Pulmonata: Camaenidae)." Contributions to Zoology 83, no. 1 (January 20, 2014): 1–40. http://dx.doi.org/10.1163/18759866-08301001.
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The present work revises the taxonomy of one group of camaenid gastropods from Timor-Leste based on the study of a large number of recently collected ethanol preserved samples as well as historic museum material, including types. By employing comparative analyses of the variation in morphological features (shell, penial anatomy) and the differentiation in mitochondrial DNA sequences of the cytochrome c oxidase subunit 1 gene (COI) and the 16S rDNA (16S), altogether nineteen species are recognized from Timor-Leste and adjacent areas in the Lesser Sunda and Moluccas, such as West-Timor, Adonara, Leti and Sermata Islands (Indonesia). Four of these species were described previously and have mostly been placed within the genus Chloritis Beck, 1837 in the few historic treatments available. Fifteen species found to be new are formally described. In contrast to the previous taxonomic treatment, placement in the genus Parachloritis Ehrmann, 1912 is proposed on grounds of comparative shell morphology. Molecular phylogenetic analyses revealed that all examined species form a monophyletic group, which encompasses diverse shell forms. While most species have shells of the general chloritid type, which are of little taxonomic utility, highly distinct shell morphs (trochoid shells, dwarf forms) have originated within this radiation in independent lineages. Morphological change has occurred in some taxonomic lineages while the bulk of Parachloritis species has maintained an ancestral shell phenotype. This phenotypic stasis is attributed to stabilizing selection in species, which have maintained associations with ancestral habitats, while distinct shell forms have evolved as result of habitat shifts. Consequently, purely shellbased taxonomies are prone to errors due to misjudging the significance of shell characters. While some Parachloritis species uncovered here were found to be narrowly endemic, others had wide distributions that include more than one island. Narrow range endemism was predominantly found in dwarf species and in species that live in high altitudes.
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Bonatsos, Dennis, Andriana Martinou, I. E. Assimakis, S. K. Peroulis, S. Sarantopoulou, and N. Minkov. "Connecting the proxy-SU(3) symmetry to the shell model." EPJ Web of Conferences 252 (2021): 02004. http://dx.doi.org/10.1051/epjconf/202125202004.
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Proxy-SU(3) symmetry is an approximation scheme extending the Elliott SU(3) algebra of the sd shell to heavier shells. When introduced in 2017, the approximation had been justified by calculations carried out within the Nilsson model. Recently our group managed to map the cartesian basis of the Elliott SU(3) model onto the spherical shell model basis, proving that the proxy-SU(3) approximation corresponds to the replacement of the intruder orbitals by their de Shalit-Goldhaber partners, paving the way for using the proxy-SU(3) approximation in shell model calculations. The connection between the proxy-SU(3) scheme and the spherical shell model has also been worked out in the original framework of the Nilsson model, with identical results.
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Cook, Alex, Alexander Nützel, and Jiri Frýda. "Two Mississippian Caenogastropod limpets from Australia and their meaning for the ancestry of the Caenogastropoda." Journal of Paleontology 82, no. 1 (January 2008): 183–87. http://dx.doi.org/10.1666/06-028.1.
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Two new limpets with a caenogastropod-type larval shell are described from the Mississippian (Early Carboniferous) of Australia and assigned to Australoscutula n. gen. of the family Pragoscutulidae. This family has previously been reported only from the Early Devonian of Europe (Czech Republic, Prague Basin). Therefore, it survived the Late Devonian biotic crisis. the fact that one of the earliest certain caenogastropods has a patelliform shell is noteworthy given most other Middle to Late Paleozoic caenogastropods are high-spired or fusiform. Pragosutulidae are interpreted as an early patelliform caenogastropod offshoot derived from coiled ancestors. the Pragoscutulidae are the oldest gastropod limpets with well-preserved larval shells. Their teleoconch is entirely limpet-shaped without helicoid coiling. However, the helicoid turbiniform larval shells suggests that this group evolved from an ancestor with turbiniform or even high-spired adult shell. Moreover, the multi-whorled dextral larval shells show that Pragoscutulidae are Caenogastropoda and document that early Caenogastropoda displayed considerable disparity.
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PITTEL, S., B. THAKUR, and N. SANDULESCU. "THE DENSITY MATRIX RENORMALIZATION GROUP AND THE NUCLEAR SHELL MODEL." International Journal of Modern Physics E 17, supp01 (December 2008): 122–32. http://dx.doi.org/10.1142/s021830130801180x.
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We summarize recent efforts to develop an angular-momentum-conserving variant of the Density Matrix Renormalization Group method into a practical truncation strategy for large-scale shell model calculations of atomic nuclei. Following a brief description of the key elements of the method, we report the results of test calculations for 48 Cr and 56 Ni . In both cases we consider nucleons limited to the 2p-1f shell and interacting via the KB3 interaction. Both calculations produce a high level of agreement with the exact shell-model results. Furthermore, and most importantly, the fraction of the complete space required to achieve this high level of agreement goes down rapidly as the size of the full space grows.
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Stelbrink, Björn, Romy Richter, Frank Köhler, Frank Riedel, Ellen E. Strong, Bert Van Bocxlaer, Christian Albrecht, et al. "Global Diversification Dynamics Since the Jurassic: Low Dispersal and Habitat-Dependent Evolution Explain Hotspots of Diversity and Shell Disparity in River Snails (Viviparidae)." Systematic Biology 69, no. 5 (February 15, 2020): 944–61. http://dx.doi.org/10.1093/sysbio/syaa011.
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Abstract The Viviparidae, commonly known as River Snails, is a dominant group of freshwater snails with a nearly worldwide distribution that reaches its highest taxonomic and morphological diversity in Southeast Asia. The rich fossil record is indicative of a probable Middle Jurassic origin on the Laurasian supercontinent where the group started to diversify during the Cretaceous. However, it remains uncertain when and how the biodiversity hotspot in Southeast Asia was formed. Here, we used a comprehensive genetic data set containing both mitochondrial and nuclear markers and comprising species representing 24 out of 28 genera from throughout the range of the family. To reconstruct the spatiotemporal evolution of viviparids on a global scale, we reconstructed a fossil-calibrated phylogeny. We further assessed the roles of cladogenetic and anagenetic events in range evolution. Finally, we reconstructed the evolution of shell features by estimating ancestral character states to assess whether the appearance of sculptured shell morphologies was driven by major habitat shifts. The molecular phylogeny supports the monophyly of the three subfamilies, the Bellamyinae, Lioplacinae, and Viviparinae, but challenges the currently accepted genus-level classification in several cases. The almost global distribution of River Snails has been influenced both by comparatively ancient vicariance and more recent founder events. In Southeast Asia, Miocene dispersal was a main factor in shaping the modern species distributions. A recurrent theme across different viviparid taxa is that many species living in lentic waters exhibit sculptured shells, whereas only one strongly sculptured species is known from lotic environments. We show that such shell sculpture is habitat-dependent and indeed evolved several times independently in lentic River Snails. Considerably high transition rates between shell types in lentic habitats probably caused the co-occurrence of morphologically distinct shell types in several lakes. In contrast, directional evolution toward smooth shells in lotic habitats, as identified in the present analyses, explains why sculptured shells are rarely found in these habitats. However, the specific factors that promoted changes in shell morphology require further work. [biogeographical analyses; fossil-calibrated phylogeny; fossil-constrained analyses; Southeast Asia; stochastic character mapping.]
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Collins, Katie S., James S. Crampton, and Michael Hannah. "Identification and independence: morphometrics of Cenozoic New ZealandSpissatellaandEucrassatella(Bivalvia, Crassatellidae)." Paleobiology 39, no. 4 (2013): 525–37. http://dx.doi.org/10.1666/12048.
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Fossil bivalve shells are well-suited for landmark/semilandmark morphometric analysis because they preserve both traces of the internal anatomy and the whole shell outline. Utilizing landmarks and semilandmarks, we have characterized internal and external shape variation in a monophyletic clade of Cenozoic New Zealand and Australian crassatellid bivalves, to test the contiguity in morphospace of species-level taxa and to quantitatively examine the “Concept of Independent Entities” of Yonge (1953). Thirteen species from two genera (SpissatellaFinlay 1926 andEucrassatellaIredale 1924) are investigated.Spissatellan. sp. C is confirmed as forming a contiguous group separate toS. trailliandS. clifdenensis. Shell outline and internal anatomy are found to covary in shape, refuting the “Concept of Independent Entities” in the study group.
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Gordynets, S., L. Charniauskaya, J. Yakhnovets, S. Kosyanenko, and A. Kiselev. "INFLUENCE OF DETERGENTS AND DISINFECTANTS ON THE QUALITY INDICATORS OF EDIBLE HEN EGGS WASHED AND DISINFECTED." Topical issues of processing of meat and milk raw materials, no. 14 (December 14, 2020): 258–69. http://dx.doi.org/10.47612/2220-8755-2019-14-258-269.
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The article presents the results of evaluating the effect of detergent and various disinfectants used for sanitary treatment of the surface of egg shells of hen edible on their quality and safety indicators. Four disinfectants belonging to different groups of drugs were selected for research: «SUNWAY DES» (peroxide), «Silversil Des» (silver-containing), «Lanex» (quaternary-ammonium compounds), «Catelon 502» (containing peracetic acid). A decrease of the mass of all samples of eggs during the whole storage period (35 days) 5,6–6,6% of initial, was increasing the height of the air chamber eggs 2,3–2,9 times, with the largest increase was in specimens treated by «Silvercel Des» and «Lanex». The decrease in egg density in
salt solution was at the same level in all
experimental samples. There was a decrease in the yolk index by 7,7% in the control sample and by 16,3–19,0% in the experimental samples, but the yolk shell did not break in all cases. By the end of
the shelf eggs life, the shell thickness and elastic deformation met the requirements. According to microbiological indicators, all egg samples during 33 days of storage met the requirements of the technical normative legal acts. Organoleptic evaluation of eggs at 16 and 35 days of storage allowed us to establish that the best, closest in organoleptics to the eggs of the control group, were the eggs of the 1st experimental group, and the worst, according to the conclusion of the majority of tasters, were the eggs of the 3rd experimental group. Based on a comprehensive analysis of the research, it was found that «SUNWAY DES» and «Catelon 502» disinfectants can be recommended for disinfecting the surface of the egg shell of edible hen eggs.
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Jackson, Donald C., Sarah E. Taylor, Vivian S. Asare, Dania Villarnovo, Jonathan M. Gall, and Scott A. Reese. "Comparative shell buffering properties correlate with anoxia tolerance in freshwater turtles." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 292, no. 2 (February 2007): R1008—R1015. http://dx.doi.org/10.1152/ajpregu.00519.2006.
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Freshwater turtles as a group are more resistant to anoxia than other vertebrates, but some species, such as painted turtles, for reasons not fully understood, can remain anoxic at winter temperatures far longer than others. Because buffering of lactic acid by the shell of the painted turtle is crucial to its long-term anoxic survival, we have tested the hypothesis that previously described differences in anoxia tolerance of five species of North American freshwater turtles may be explained at least in part by differences in their shell composition and buffering capacity. All species tested have large mineralized shells. Shell comparisons included 1) total shell CO2 concentration, 2) volume of titrated acid required to hold incubating shell powder at pH 7.0 for 3 h (an indication of buffer release from shell), and 3) lactate concentration of shell samples incubated to equilibrium in a standard lactate solution. For each measurement, the more anoxia-tolerant species (painted turtle, Chrysemys picta; snapping turtle, Chelydra serpentina) had higher values than the less anoxia-tolerant species (musk turtle, Sternotherus odoratus; map turtle, Graptemys geographica; red-eared slider, Trachemys scripta). We suggest that greater concentrations of accessible CO2 (as carbonate or bicarbonate) in the more tolerant species enable these species, when acidotic, to release more buffer into the extracellular fluid and to take up more lactic acid into their shells. We conclude that the interspecific differences in shell composition and buffering can contribute to, but cannot explain fully, the variations observed in anoxia tolerance among freshwater turtles.
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Schriver, Kenneth E., John L. Persson, Eric C. Honea, and Robert L. Whetten. "Electronic shell structure of group-IIIA metal atomic clusters." Physical Review Letters 64, no. 21 (May 21, 1990): 2539–42. http://dx.doi.org/10.1103/physrevlett.64.2539.
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Zyryanova, Olga V. "Composite operators in functional renormalization group approach." Modern Physics Letters A 32, no. 28 (September 4, 2017): 1750153. http://dx.doi.org/10.1142/s021773231750153x.
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The gauge dependence problem of the effective action for general gauge theories in the framework of a modified functional renormalization group approach proposed recently is studied. It is shown that the effective action remains gauge-dependent on-shell.
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Magee, M. R., K. Maguire, R. Kotak, and S. A. Sim. "Exploring the diversity of double-detonation explosions for Type Ia supernovae: effects of the post-explosion helium shell composition." Monthly Notices of the Royal Astronomical Society 502, no. 3 (January 25, 2021): 3533–53. http://dx.doi.org/10.1093/mnras/stab201.
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ABSTRACT The detonation of a helium shell on top of a carbon–oxygen white dwarf has been argued as a potential explosion mechanism for Type Ia supernovae (SNe Ia). The ash produced during helium shell burning can lead to light curves and spectra that are inconsistent with normal SNe Ia, but may be viable for some objects showing a light-curve bump within the days following explosion. We present a series of radiative transfer models designed to mimic predictions from double-detonation explosion models. We consider a range of core and shell masses, and systematically explore multiple post-explosion compositions for the helium shell. We find that a variety of luminosities and time-scales for early light-curve bumps result from those models with shells containing 56Ni, 52Fe, or 48Cr. Comparing our models to SNe Ia with light-curve bumps, we find that these models can reproduce the shapes of almost all of the bumps observed, but only those objects with red colours around maximum light (B − V ≳ 1) are well matched throughout their evolution. Consistent with previous works, we also show that those models in which the shell does not contain iron-group elements provide good agreement with normal SNe Ia of different luminosities from shortly after explosion up to maximum light. While our models do not amount to positive evidence in favour of the double-detonation scenario, we show that provided the helium shell ash does not contain iron-group elements, it may be viable for a wide range of normal SNe Ia.
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Bieler, Rüdiger, Timothy M. Collins, Rosemary Golding, and Timothy A. Rawlings. "A novel and enigmatic two-holed shell aperture in a new species of suspension-feeding worm-snail (Vermetidae)." PeerJ 7 (February 28, 2019): e6569. http://dx.doi.org/10.7717/peerj.6569.
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Shell aperture modifications are well known in terrestrial and aquatic gastropods, with apertural lip thickening and tooth development common in species with terminal (determinate) shell growth. In contrast, secondary shell openings are rare in snails and are largely limited to slit shells, keyhole limpets, and abalone of the Vetigastropoda. When such features occur in other groups, they are noteworthy and raise interesting questions concerning the functional/adaptive significance of these shell modifications. Here we report on one such modification in a newly described species of vermetid snail. Members of the worm-snail family Vermetidae are sessile, suspension-feeding caenogastropods found in warm temperate to tropical marine environments worldwide. As juveniles, vermetids permanently cement their shells to hard substrata and subsequently produce irregularly coiled polychaete-like shell tubes with indeterminate growth and typically a simple circular shell aperture. In one previously studied group (genusCupolaconcha), the aperture can be covered by a shell dome with a central slit that retains its widest opening in the center of the aperture. Vermetid specimens collected in the barrier reefs of Belize and the Florida Keys show an extreme aperture modification previously unknown in Gastropoda, in which the shell opening is covered by an apertural dome that leaves two equal-sized circular holes, each corresponding to the inflow and outflow water exchange currents of the animal’s mantle cavity. The function of this perforated apertural dome is unknown, and it is in some ways antithetical to the suspension feeding habit of these snails. Further field and laboratory-based studies will be needed to clarify the functional significance and trade-offs of this unique morphology. The new taxon, which is not closely related to the previously described dome-building cladeCupolaconcha, is described and named asVermetus biperforatusBieler, Collins, Golding & Rawlings n. sp.
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Sari, Rima Parwati, Sri Agus Sudjarwo, Retno Pudji Rahayu, Widyasri Prananingrum, Syamsulina Revianti, Hansen Kurniawan, and Aisah Faiz Bachmid. "The effects of Anadara granosa shell-Stichopus hermanni on bFGF expressions and blood vessel counts in the bone defect healing process of Wistar rats." Dental Journal (Majalah Kedokteran Gigi) 50, no. 4 (December 30, 2017): 194. http://dx.doi.org/10.20473/j.djmkg.v50.i4.p194-198.
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Background: Bone damage can be caused by various factors with treatment usually involving graft materials being applied to the defective area. Moreover, in the bone defect healing process, blood vessels are also considered to be an important energy source for cell proliferation. One of the angiogenic factors playing an important role in blood vessel formation is basic fibroblast growth factor (bFGF). Furthermore, synthesized hydroxyapatite derived from Anadara granosa (AG) shells constitutes one of the potential materials for use in bone graft. The gold sea cucumber genus Stichopus hermanni (SH) possesses the ability to stimulate endothelial progenitor cells inducing bFGF. Purpose: This study aims to investigate the effects of AG shells and SH on bFGF expressions and blood vessel counts within the bone healing process. Methods: Twenty four male Wistar rats were divided into three groups, namely: a control group (C), a treatment group was administered with blood cockle shell (AG), and a treatment group with blood cockle shell and golden sea cucumber (AG+SH). Defects were made on their femurs measuring half the diameter of a circular, no. 018. bur These rats were subsequently sacrificed on day 7 after surgery. The expressions of bFGF were measured by means of IHC technique, while the number of blood vessels was quantified using HE technique. The resulting data was subjected to statistical analysis using an Anova test followed by an LSD test (p < 0.05). Results: The one-way Anova test results combined with those of an LSD test showed there to be significant differences in bFGF expressions and blood vessel counts between the control group (K) and the treatment group (AG) as well as between the treatment group (AG) and the treatment group (AG+SH). Conclusions: A combination of Anadara granosa shell and Stichopus hermanni can increase the expression of bFGF and the number of blood vessels on day 7 during the bone healing process in Wistar rats.
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Nguyen, Van, Jianxiu Hao, and Weihong Wang. "Ultraviolet Weathering Performance of High-Density Polyethylene/Wood-Flour Composites with a Basalt-Fiber-Included Shell." Polymers 10, no. 8 (July 27, 2018): 831. http://dx.doi.org/10.3390/polym10080831.
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In this study, high-density polyethylene (HDPE)/wood-flour composites with a basalt fiber (BF)-reinforced shell were prepared by coextrusion. After exposing these composites to ultraviolet weathering for 2000 h, their performances were examined from their measurements of color, surface morphology, and chemical properties. As a control, UV326 was also added to the shell formula. The weathered surface was characterized by scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that the shells filled with 8% and 12% BF exhibited low lightness and color change in comparison to those filled with UV326 for a limited duration. The composite shells with the combined BF and UV326 exhibited the least discoloration and surface cracks. FTIR spectra revealed that the oxidation of the composites increases with the duration of exposure to the assessment of the carbonyl group concentration on the surface. The combination of BF and UV326 revealed a synergistic effect on the alleviation of the photooxidation of wood-plastic composite shell layers, verifying the UV-shielding effect.
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Chousalkar, K. K., and J. R. Roberts. "Effects of Australian strains of infectious bronchitis virus on internal and external quality of hen eggs." Animal Production Science 49, no. 2 (2009): 162. http://dx.doi.org/10.1071/ea08167.
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The effects of two Australian strains of infectious bronchitis virus (IBV-T and N1/88) on the internal and external quality of eggs were studied in unvaccinated Isa Brown hens in full lay. Overall, there was no decline in egg production in either of the infected groups. However, there were some long-lasting negative effects on the egg internal quality of T-infected hens. Negative effects on internal quality in the N1/88-infected group were relatively short term. Yolk colour score was lower only in T-infected hens. Egg shell quality was affected only in terms of loss of egg shell colour. IBV infection resulted in paler egg shells in both the infected groups. Paler egg shells may not be regarded well by consumers. The egg shape index was lower in both infected groups.
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Pavlovski, Zlatica, Dusko Vitorovic, Zdenka Skrbic, and Milos Lukic. "The effect of oviposition and time of marble addition to feed on quality of table eggs." Biotehnologija u stocarstvu 21, no. 3-4 (2005): 97–105. http://dx.doi.org/10.2298/bah0504097p.
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Investigation of the effect of oviposition and time of addition of marble was carried out on 360 Shaver layer hens divided into three groups. During six week trial (from age of 72 to 78 weeks) hens were fed standard diet according to recommendations for Shaver genotype where main source of Calcium was limestone. First group of hens was control and they were fed standard mixture, second group of hens received additionally each morning 2g of ground marble distributed over the feed, and third group of hens received 2 g of ground marble twice a day - Ig in the morning (8 a.m) and Ig in the afternoon (1 p.m). At the end of each week period quality of fresh laid eggs was investigated. Following egg quality characteristics were measured: egg mass (g), shell mass (g), shell thickness (um), shell deformation (um), shell breaking force (kg) and Haugh units were calculated. Obtained results have shown that oviposition had no significant effect on investigated traits. Addition of large particles of marble had positive effect on strength of egg shell. Compared to control group, morning addition of 2g of marble per hen or addition of Ig.in the morning and Ig in the afternoon caused statistically highly significant increase of egg shell strength expressed through greater breaking force and lower value of shell deformation as well as higher values of shell mass and thickness. Compared to control and trial group I, quality of egg white expressed through Haugh units was significantly lower in trial group III.
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Kamadjaja, Michael JK, Bambang AS Tumali, Harry Laksono, Nike Hendrijantini, Melinda L. Ariani, Natasia, and Tata P. Mawantari. "Effect of Socket Preservation Using Crab Shell-Based Hydroxyapatite in Wistar Rats." Recent Advances in Biology and Medicine 6 (2020): 1. http://dx.doi.org/10.18639/rabm.2020.1116232.
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Tooth extraction can cause 1.5-2 mm (vertical) and 40-50% (horizontal) alveolar bone resorption to occur for 6 months after extraction and will continue if it is not treated. Alveolar bone resorption will affect the retention, stability, and comfort in the use of dentures because adequate alveolar bone volume and structure of alveolar ridge are very important to obtain optimal function and prosthetic reconstruction. Currently, there are techniques and materials that can be used to minimize bone resorption. Preservation of alveolar ridges with crab shell-based hydroxyapatite can minimize bone resorption because it has good biocompatibility, osteoconduction, and osteoinduction. The aim of this study is to prove the effectiveness of hydroxyapatite from crab shells in increasing the area of bone trabeculae, transforming growth factor-beta 1(TGF-β1), and alkaline phosphatase (ALP). This laboratory research is an experimental laboratory work with a post-test group design. Crab shell-based hydroxyapatite gel (Portunus pelagicus) was given after the post-tooth socket extraction of the left lower central incisor of Wistar rats, observing the area of trabeculae, TGF-β1, and ALP on the 14th day and 28th day. Hydroxyapatite is made from the calcination process of crab shells using a furnace at 1000°C for 2 h followed by sifting to powder. The powder is added with carrageenan and distilled water so that it becomes a gel preparation. The results of this study were analyzed using the One-way ANOVA test with IBM SPSS version 20. The area of trabeculae, TGF-β1, and ALP between the control group and the treatment group showed p<0.05, which means there were significant differences between the groups. The study showed that hydroxyapatite from the crab shell (P. pelagicus) can increase the area of trabeculae, TGF-β1, and ALP in the post-extraction socket of Wistar rat’s teeth.
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Eyink, Gregory L. "Renormalization group and operator product expansion in turbulence: Shell models." Physical Review E 48, no. 3 (September 1, 1993): 1823–38. http://dx.doi.org/10.1103/physreve.48.1823.
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Nardoni, S., P. Lungonelli, R. Papini, L. Mugnaini, and F. Mancianti. "Shell mycosis in a group of Hermann's tortoises (Testudo hermanni)." Veterinary Record 170, no. 3 (November 3, 2011): 76.2–76. http://dx.doi.org/10.1136/vr.100261.
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Lima Neto, G. B., F. Durret, T. F. Laganá, R. E. G. Machado, N. Martinet, J. C. Cuillandre, and C. Adami. "NGC 4104: A shell galaxy in a forming fossil group." Astronomy & Astrophysics 641 (September 2020): A95. http://dx.doi.org/10.1051/0004-6361/201936098.
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Context. Groups are the most common association of galaxies in the Universe and they are found in different configuration states, such as loose, compact, and fossil groups. Aims. We studied the galaxy group MKW 4s, dominated by the giant early-type galaxy NGC 4104 at z = 0.0282, with the aim of understanding the evolutionary stage of this group and to place it within the framework of the standard ΛCDM cosmological scenario. Methods. We obtained deep optical data with CFHT/Megacam (g and r bands) and we applied both the GALFIT 2D image fitting program and the IRAF/ELLIPSE 1D radial method to model the brightest group galaxy (BGG) and its extended stellar envelope. We also analysed the publicly available XMM-Newton and Chandra X-ray data. From N-body simulations of dry-mergers with different mass ratios of the infalling galaxy, we were able to constrain the dynamical stage of this system. Results. Our results show a stellar shell system feature in NGC 4104 and an extended envelope that was reproduced by our numerical simulations of a collision with a satellite galaxy taking place about 4−6 Gyr ago. The initial pair of galaxies had a mass ratio of at least 1:3. Taking into account the stellar envelope contribution to the total r band magnitude and the X-ray luminosity, MKW 4s falls into the category of a fossil group. Conclusions. Our results show that we are witnessing a rare case of a shell elliptical galaxy in a forming fossil group.
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Born, Gregory, and Isaiah Shavitt. "A unitary group formulation of open-shell electron propagator theory." International Journal of Quantum Chemistry 20, S15 (June 19, 2009): 63. http://dx.doi.org/10.1002/qua.560200807.
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Attiaoui, Anis, Stephan Wirth, André-Pierre Blanchard-Dionne, Michel Meunier, J. M. Hartmann, Dan Buca, and Oussama Moutanabbir. "Extreme IR absorption in group IV-SiGeSn core-shell nanowires." Journal of Applied Physics 123, no. 22 (June 14, 2018): 223102. http://dx.doi.org/10.1063/1.5021393.
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Judd, B. R. "Applicability of the Lie group F4to the atomic f shell." Journal of Physics B: Atomic, Molecular and Optical Physics 28, no. 7 (April 14, 1995): L203—L207. http://dx.doi.org/10.1088/0953-4075/28/7/001.
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Johnston, Roy L. "Closed-shell three-connected clusters: topological and group-theoretical aspects." Journal of the Chemical Society, Faraday Transactions 87, no. 20 (1991): 3353. http://dx.doi.org/10.1039/ft9918703353.
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Tröster, A. "Wilsonʼs momentum shell renormalization group from Fourier Monte Carlo simulations." Computer Physics Communications 182, no. 9 (September 2011): 1837–41. http://dx.doi.org/10.1016/j.cpc.2010.11.005.
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Tan, Suo Kui, Xiao Ping Song, Song Ji, Hong Zhao, Min Wu, and Hong Yan Guo. "Electrorheological Properties of Ni-Group Nano Particles and Multilayer Compound Polar Molecule Modify." Advanced Materials Research 476-478 (February 2012): 1749–52. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.1749.
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This paper emphasis has researched the ER properties of Ni group core-shell nano particles modifier with Urea，SDBS and other polar molecule，analysis the relationship among ER properties and polar molecule type ，compound modifier under different electric field or magnetic field. It is found that the shear stress increasing with adding polar molecule, compound polar molecule modify can marked advance the properties of Ni group core-shell particles ER fluid.
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Ji, Yinghui, Xue Yang, Dong Yang, and Rongqing Zhang. "PU14, a Novel Matrix Protein, Participates in Pearl Oyster, Pinctada Fucata, Shell Formation." Marine Biotechnology 23, no. 2 (March 10, 2021): 189–200. http://dx.doi.org/10.1007/s10126-020-10014-3.
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AbstractBiomineralization 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.
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Kumagi, Hitoshi, and Kazuhisa Yano. "Synthesis and Characterization of Au-Loaded Core/Shell Mesoporous Silica Spheres Containing Propyl Group in the Shell." Chemistry of Materials 22, no. 17 (September 14, 2010): 5112–18. http://dx.doi.org/10.1021/cm1010899.
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Püntener, Christian, Jérémy Anquetin, and Jean-Paul Billon-Bruyat. "The comparative osteology of Plesiochelys bigleri n. sp., a new coastal marine turtle from the Late Jurassic of Porrentruy (Switzerland)." PeerJ 5 (June 28, 2017): e3482. http://dx.doi.org/10.7717/peerj.3482.
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Background During the Late Jurassic, several groups of eucryptodiran turtles inhabited the shallow epicontinental seas of Western Europe. Plesiochelyidae are an important part of this first radiation of crown-group turtles into coastal marine ecosystems. Fossils of Plesiochelyidae occur in many European localities, and are especially abundant in the Kimmeridgian layers of the Swiss Jura Mountains (Solothurn and Porrentruy). In the mid-19th century, the quarries of Solothurn (NW Switzerland) already provided a large amount of fossil turtles, most notably Plesiochelys etalloni, the best-known plesiochelyid species. Recent excavations in the Porrentruy area (NW Switzerland) revealed new fossils of Plesiochelys, including numerous well-preserved shells with associated cranial and postcranial material. Methods/results Out of 80 shells referred to Plesiochelys, 41 are assigned to a new species, Plesiochelys bigleri n. sp., including a skull–shell association. We furthermore refer 15 shells to Plesiochelys etalloni, and 24 shells to Plesiochelys sp. Anatomical comparisons show that Plesiochelys bigleri can clearly be differentiated from Plesiochelys etalloni by cranial features. The shell anatomy and the appendicular skeleton of Plesiochelys bigleri and Plesiochelys etalloni are very similar. However, a statistical analysis demonstrates that the thickness of neural bones allows to separate the two species based on incomplete material. This study furthermore illustrates the extent of intraspecific variation in the shell anatomy of Plesiochelys bigleri and Plesiochelys etalloni.
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Wall-Palmer, Deborah, Mona Hegmann, Erica Goetze, and Katja T. C. A. Peijnenburg. "Resolving species boundaries in the Atlanta brunnea species group (Gastropoda, Pterotracheoidea)." ZooKeys 899 (December 12, 2019): 59–84. http://dx.doi.org/10.3897/zookeys.899.38892.
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Atlantid heteropods are a family of holoplanktonic marine gastropods that occur primarily in tropical and subtropical latitudes. Atlantids bear a delicate aragonitic shell (<14 mm) and live in the upper ocean, where ocean acidification and ocean warming have a pronounced effect. Therefore, atlantids are likely to be sensitive to these ocean changes. However, we lack sufficiently detailed information on atlantid taxonomy and biogeography, which is needed to gain a deeper understanding of the consequences of a changing ocean. To date, atlantid taxonomy has mainly relied on morphometrics and shell ornamentation, but recent molecular work has highlighted hidden diversity. This study uses an integrated approach in a global analysis of biogeography, variation in shell morphology and molecular phylogenies based on three genes (CO1, 28S and 18S) to resolve the species boundaries within the Atlanta brunnea group. Results identify a new species, Atlanta vanderspoeli, from the Equatorial and South Pacific Ocean, and suggest that individuals of A. brunnea living in the Atlantic Ocean are an incipient species. Our results provide an important advance in atlantid taxonomy and will enable identification of these species in future studies of living and fossil plankton.
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A. N. Stringer, I., Karl E. C. Brennan, Melinda L. Moir, G. R. Parrish, Jonathan D. Majer, and G. H. sherley. "Population structure, growth and longevity of Placostylus hongii (Pulmonata: Bulimulidae) on Tawhiti Rahi Island, Poor Knights Islands, New Zealand." Pacific Conservation Biology 9, no. 4 (2003): 241. http://dx.doi.org/10.1071/pc040241.
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Placostylus hongii, a threatened snail species, was studied on Tawhiti Rahi Island in the Poor Knights Islands group off the east coast of northern New Zealand between 1998 and 2000. Most live snails and empty shells were adults (83% and 85% respectively) and the low proportion of empty adult shells (36%) compared with live adult snails found in an area last burnt in the late 1950s suggests that the population there is still recovering. Growth was measured using snails recaptured with the aid of harmonic radar transponders attached to their shells. Increase in shell length varied from 6 to 25 mm per year in juveniles with shells >38 mm long, but it slowed when juveniles approached maturity (adult shell length 55-89 mm). The juvenile period is greater than three years and growth in shell length virtually stops when a thick aperture lip develops. This lip continues to thicken at 0.1-0.4 mm per year and can reach a maximum thickness of 15.5 mm, indicating that adults may live 10 years and possibly more than 30 years. A comparison of our data with two previous studies on the same population and on Aorangi Island, in the Poor Knights Islands group, confirms that these snails are slow developing, have low recruitment of adults, and that populations are probably maintained by a pool of long-lived adults. Our results indicate that following predator control on the mainland, the recovery of a snail population is likely to be slow. Once a population has recovered it could be maintained by intensively controlling rodents for periods of greater than three years (to allow recruitment of adults into the population) alternating with longer periods without control.
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Ferdynanto, Reyhan Alvaryan, Priska Evita Setia Dharmayanti, Putu Tahlia Krisna Dewi, and Widyasri Prananingrum. "The effect of various concentrations of HA-TCP derived from cockle shell synthesis on scaffold porosity." Dental Journal (Majalah Kedokteran Gigi) 51, no. 3 (September 30, 2018): 114. http://dx.doi.org/10.20473/j.djmkg.v51.i3.p114-118.
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Background: Porosity is an important property that must be possessed by scaffold due to its role in new bone growth. Hydroxyapatite is a scaffold material with a composition resembling that of bone that can be synthesized from cockle shell (Anadara granosa). Purpose: This research aimed to determine the effects of various HA-TCP concentrations (wt%) derived from cockle shell synthesis on scaffold porosity. Methods: HA-TCP was synthesized from cockle shells using a hydrothermal method at 200o C with a 12-hour sintering process period. An XRD test was subsequently carried out to determine the composition of hydroxyapatite (HA) and tricalcium phosphate (TCP) compounds. Eighteen scaffold samples (n=6) were then produced using a freeze dry method and divided into three groups, namely; Group 1 (K1) treated with 5% HA-TCP, Group 2 (K2) treated with 25% HA-TCP and Group 3 (K3) treated with 50% HA-TCP. Thereafter, a scaffold porosity test was conducted using liquid displacement method. Scaffold porosity was observed by means of an SEM image. A One-Way ANOVA test was subsequently performed, followed by an LSD Post-Hoc test (p <0.05). Results: The results of the XRD test showed that the percentage of HA was 51.5%, while TCP was 16.8%. The porosity of the scaffolds was within the range of 67.24% - 80.17%. The highest porosity was found in Group 1, while the lowest occurred in Group 3. There were significant differences in all groups. Conclusion: The concentration of HA-TCP derived from the synthesis of cockle shells affects the porosity of scaffold. The lower the concentration of HA-TCP, the higher the scaffold porosity.
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Burdíková, Zuzana, Martin Čapek, Pavel Ostašov, Jiří Machač, Radek Pelc, Edward A. D. Mitchell, and Lucie Kubínová. "Testate Amoebae Examined by Confocal and Two-Photon Microscopy: Implications for Taxonomy and Ecophysiology." Microscopy and Microanalysis 16, no. 6 (November 19, 2010): 735–46. http://dx.doi.org/10.1017/s1431927610094031.
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AbstractTestate amoebae (TA) are a group of free-living protozoa, important in ecology and paleoecology. Testate amoebae taxonomy is mainly based on the morphological features of the shell, as examined by means of light microscopy or (environmental) scanning electron microscopy (SEM/ESEM). We explored the potential applications of confocal laser scanning microscopy (CLSM), two photon excitation microscopy (TPEM), phase contrast, differential interference contrast (DIC Nomarski), and polarization microscopy to visualize TA shells and inner structures of living cells, which is not possible by SEM or environmental SEM. Images captured by CLSM and TPEM were utilized to create three-dimensional (3D) visualizations and to evaluate biovolume inside the shell by stereological methods, to assess the function of TA in ecosystems. This approach broadens the understanding of TA cell and shell morphology, and inner structures including organelles and endosymbionts, with potential implications in taxonomy and ecophysiology.
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Schejter, Laura, Mariana Escolar, and Claudia Bremec. "Variability in epibiont colonization of shells of Fusitriton magellanicus (Gastropoda) on the Argentinean shelf." Journal of the Marine Biological Association of the United Kingdom 91, no. 4 (September 27, 2010): 897–906. http://dx.doi.org/10.1017/s0025315410001359.
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An inventory of the main epibiont organisms on living specimens, on empty shells and on pagurized shells of Fusitriton magellanicus collected in Zygochlamys patagonica fishing grounds off Argentina is provided here. Additionally, considering that the presence of the thick, hairy periostracum could be an inhibitor of boring and encrusting species, we analyse the presence of a periostracum in living F. magellanicus in relation to the presence of epibionts. More than 70% of all shells bore encrusting organisms (of at least 30 taxa) but only a small proportion of shells was heavily fouled, the majority of living, empty and pagurized shells being lightly or moderately fouled. Polychaetes were the most common epibiont group (present on more than 60% of shells) while sponges and ascidians were responsible for the majority of the heavily fouled living gastropods. In general, specimens had a moderate level of encrustation and, simultaneously, a low or medium coating of periostracum. Hairy gastropods (only 14% of the sampled specimens) had few or no epibionts. A relationship between the size of the shell and the level of encrustation was only found in living gastropods. Fusitriton magellanicus is the second species in importance (after the Patagonian scallop) for the provision of a hard settlement substrate in the shelf-break frontal area of the Argentine Sea.
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Fithria, Risha Fillah, Ririn Lispita Wulandari, Devi Nisa Hidayati, Pia Annisa, and Nilam Eka Putri. "ANTITHROMBOCYTOPENIA ACTIVITY OF PEANUT SHELL (Arachis hypogea L.) EXTRACT AND INFUSA ON HEPARIN INDUCED BALB/C MICE." Jurnal Tumbuhan Obat Indonesia 12, no. 1 (July 29, 2019): 1–9. http://dx.doi.org/10.22435/jtoi.v12i1.1266.
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ABSTRACT
Certain group of people empirically use peanut shell stew in the treatment of thrombocytopenia due to dengue fever. The active compounds suspected to play a role in the activity of thrombocytopenia from peanut shell are flavonoids. Flavonoids can be extracted using heat and cold methods. This study aims to determine the antithrombocytopenia activity of peanut shell extract and infusa on heparin induced Balb/C mice. This study is an experimental research with randomized matched pre and postest control group design. Peanut shell extraction was done in a cool way by maseration using 70% ethanol solvent, and hot way by infundation using aquadest solvent. Forty-eight Balb/C mice were divided into 8 groups consisting of control group CMC Na 0.5 mL/20gBW/day, control group aquadest 0,5mL/20gBW/day, 3 groups of peanut shell ethanol extract (0.019, 0.038, and 0.076) g/20gBW/day, and 3 groups of peanut shell infusa (0.026, 0.052; 0.104) g/20gBW/day. All treatments were given orally. The decrease of platelet count in Balb/C mice using 26 UI/20gBW subcutan heparin induction. The measurement of the platelet count is performed by taking blood samples in the lateral veins of the tail. Platelet counts data before and after treatment was tested with dependent T-test. Differences in platelet increases across the groups were tested by 2 way anova and continued with a LSD test with 95% confidence level. The results showed that peanut shell ethanol extract had better antitrombocytopenia activity than peanut shell infusa.
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Rodrigues, Felipe Barta, Michelle Rezende Duarte, Rosa Cristina Corrêa Luz de Souza, Abílio Soares-Gomes, and Edson Pereira Silva. "Holocene crustaceans from the Tarioba shell mound, Rio das Ostras, Rio de Janeiro, Brazil." Check List 12, no. 2 (March 28, 2016): 1865. http://dx.doi.org/10.15560/12.2.1865.
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Crustacean remains from the Tarioba shell mound (Sambaqui da Tarioba) archaeological site were investigated in order to produce a reference inventory of this taxonomic group. Information on past crustacean diversity is important for establishing baselines on biodiversity, as well as recovering paleoenvironmental information and comprehension of evolutionary change patterns for the Brazilian coast. The archaeological site was excavated by delayering the soil by artificial 10 cm sections which revealed five archaeological stratigraphic layers. A sample of mollusk shells for each of these layers was used for dating based on the C14 method. The results show an occupation period of 550 yr for the Tarioba shell mound, with dates ranging between 4,070 cal BP (beginning of occupation) and 3,520 cal BP (occupation ending) and record nine species of crustaceans from the shell mound. However, a reduction of biodiversity over time was found that was not statically significant. Therefore, it seems that patterns of composition, richness and distribution of crustaceans have been stable in the last 4,070 years BP.
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Ni'mah, Yatim Lailun, Harmami Harmami, Ita Ulfin, Suprapto Suprapto, and Clarissa Welny Saleh. "Water-soluble chitosan preparation from marine sources." Malaysian Journal of Fundamental and Applied Sciences 15, no. 2 (April 16, 2019): 159–63. http://dx.doi.org/10.11113/mjfas.v15n2.971.
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Water-soluble chitosan (WSC) has been derived from different marine sources such as squid pen, shrimp, mussel, and crab shells. Chitosan was obtained by deacetylation of chitin. Degradation of chitosan by hydrogen peroxide would produce WSC. Demineralization process was optimized by varying incubation time and temperature to minimize the mineral content in chitin. WSC that obtained was characterized by Fourier-transform infrared spectroscopy (FTIR) to calculate the deacetylation degree. Deacetylation degree of WSC was also studied by titrimetric method. The ash content of chitin from marine sources was measured to obtain the optimum demineralization incubation time. The optimum incubation time for demineralization process was 12 hours and stirred at 50 rpm. Recovery and deacetylation degree of WSC were found to be varied and depended on the source of WSC. Each sample of WSC from shrimp shell, mussel shell, squid pen and crab shell has the degree of deacetylation of 64.18%, 35.03%, 58.04% and 53.91% respectively. The presence of amine group was confirmed from FTIR spectra ofsynthesized WSC.
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King, R. B. "Group-theoretical structure of the atomic f shell: connection with the non-Euclidean heptakisoctahedral (didodecahedral) group." Molecular Physics 104, no. 20-21 (October 20, 2006): 3261–68. http://dx.doi.org/10.1080/00268970601075287.
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Kamadjaja, Michael Josef Kridanto, Alya Nisrina Sajidah Gatia, Agtadilla Novitananda, Lintang Maudina, Harry Laksono, Agus Dahlan, Bambang Agustono Satmoko Tumali, and Muhammad Dimas Aditya Ari. "Evaluation of osteogenic properties after application of hydroxyapatite-based shells of Portunus pelagicus." Dental Journal (Majalah Kedokteran Gigi) 54, no. 3 (August 11, 2021): 119. http://dx.doi.org/10.20473/j.djmkg.v54.i3.p119-123.
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Background: After tooth extraction, the socket leaves a defect on the alveolar bone. The administration of shell crab-derived hydroxyapatite maintains bone dimensions that are important for achieving successful prosthodontic treatment. Purpose: The aim of the study was to determine the osteogenic properties, such as the number of osteoclasts, osteoblasts and osteocytes, after the application of hydroxyapatite-based shell crab in the post-extraction sockets of Wistar rats. Methods: There were two groups: the control group (K) and the treatment group (T). Wistar rats were randomly divided into control and treatment groups. After tooth extraction, hydroxyapatite gel derived from Portunus pelagicus shells was applied to the tooth sockets of Wistar rats. Observations and calculations of osteoclasts, osteoblasts and osteocytes were carried out on the 14th and 28th days under a light microscope with 400 times magnification. Statistical analysis was performed using one-way ANOVA. Results: There was a significant difference (p<0.05) between the K14 and P14 groups, K28 and P28 groups, K14 and K28 groups, and P14 and P28 groups. The results indicated that there were significant differences between groups of variables. Conclusion: The application of shell crab-derived hydroxyapatite (Portunus pelagicus) was able to decrease the number of osteoclasts and increase the number of osteoblasts and osteocytes.