Shell Form Research Articles

Phylogenetic assessment of endangered and look-alike Pigtoe species in a freshwater mussel diversity hotspot.

The Green River in Kentucky in the eastern United States is a freshwater mussel biodiversity hotspot, with 71 known species. Among them, the endangered Pleurobema plenum coexists with other morphologically similar species in the genera Fusconaia and Pleurobema, known colloquially as "pigtoes." Identification of species in these genera is challenging even for mussel experts familiar with them. In our study, the correct identification of these species by experts ranged from 57% to 83%. We delineated taxonomic boundaries among seven species and tested for cryptic biodiversity among these look-alike mussels utilizing mitochondrial and nuclear DNA sequence variation. Phylogenetic analysis of combined (1215 bp) mitochondrial DNA cytochrome oxidase I (COI) and NADH dehydrogenase 1 (ND1) genes showed five well-diverged groups that included F.flava, F.subrotunda, P.cordatum, and P.plenum as distinct clades, with P.sintoxia and P.rubrum grouped into a single clade. While our mitochondrial DNA analyses did not distinguish P.sintoxia and P.rubrum as phylogenetically distinct species, the typical shell forms of these two nominal taxa are very distinct. Further phylogenetic analysis using nuclear ribosomal transcribed spacer region subunit I (ITS1) DNA sequences also showed that P.sintoxia and P.rubrum were not distinct lineages. No cryptic species were detected in the Fusconaia and Pleurobema samples analyzed from the Green River. The highest haplotype diversity (h), average number of nucleotide differences (k), and nucleotide diversity (π) were observed for F.subrotunda at both the COI (h=0.896, k=3.805, π=0.00808) and ND1 (h=0.984, k=6.595, π =0.00886) markers, with similarly high genetic diversity in the other taxa. Our results give managers confidence that cryptic taxa do not occur within or among these morphologically similar species in the Green River, and populations appear genetically diverse, indicative of large and healthy populations.

Stability of shallow shells with local changes in strength characteristics

The authors deal with the structures of buildings in the form of shallow shells with some damage. The derivation of equations is given taking into account the geometric nonlinearity of the work of a thin-walled structure. A technique for solving systems of equations using the Bubnov - Galyorkin method is given. The work of the structure with various ways of fixing the edges is simulated. Damage is specified by changing the modulus of elasticity in an arbitrary section of the structure. The influence of the shape and location of the defect on the value of the critical load is investigated. The results of the studies carried out are given in a dimensionless form and illustrated by graphs, which makes it convenient to use them in engineering calculations. Recommendations are given for correcting the shape and thickness of coating structures in the form of shallow shells in order to maintain their bearing capacity in the event of defects. The proposed method can be used to determine and investigate the stress-strain state of structures in the form of shallow shells, taking into account the geometric nonlinearity of work in the presence of defects in them. The constructed graphs of the dependence of the critical load on various parameters make it possible to evaluate the operation of structures, taking into account changes in various factors at various stages of the structure's operation. The use of varying characteristics of the reduction in the modulus of elasticity, which appears because of the occurrence of a defect, shows results that are close to real conditions.

Complex Building Forms Roofed with Transformed Shell Units and Defined by Saddle Surfaces.

A novel method and description of creating diversified complex original building forms roofed with a number of transformed folded shell units developed on the basis of a novel reference polyhedral network and arranged according to a reference surface with the negative Gaussian curvature is presented. For that purpose, specific reference polyhedral networks is are defined as a complex material deliberately composed of many regular tetrahedrons that are arranged regularly to obtain original attractive complex general building forms. The proposed method is a significant extension of the previous method for shaping roof structures with the positive Gaussian curvature and fills existing gaps in current scientific knowledge. The extended method enables the designer to significantly increase the variety of the created complex shell roof forms and plane-walled folded elevation forms of buildings and to define the shapes of their rod structural systems. It allows one to overcome the existing significant geometric and material limitations related to shape transformations of nominally flat rectangular folded steel sheets into different shell forms. The developed extension is based on formation of a set of properly connected tetrahedra as a material determining different (a) inclination of elevation walls to the vertical, and (b) distribution of many individual warped roof shells in accordance with the properties of a regular surface with negative Gaussian curvature. A number of the adopted specific sets of division coefficients (parameters) is used for determining the entire network and its complete tetrahedra. The presented description makes it possible to adopt appropriate assumptions and data and then employ the innovative method to obtain the expected characteristics of the unconventional building form shaped. The presented three different special forms created with the help of the novel method and the appropriately selected diversified values of the division coefficients of pairs of the vertices of a polyhedral reference network, a polygonal eaves network and points of a reference surface confirm the innovative scientific nature of the obtained results. The method has to be computationally aided due to the complexity of mathematical operations and the need to visualize the designed forms.

Silicon Cutting Waste Derived Silicon Nanosheets with Adjustable Native SiO2 Shell for Highly‐Stable Lithiation/Delithiation

Silicon is an excellent candidate for the next generation of ultra-high performance anode materials, with the rapid iteration of the lithium-ion battery industry. High-quality silicon sources are the cornerstone of the development of silicon anodes, and silicon cutting waste (SCW) is one of them while still faces the problems of poor performance and unclear structure-activity relationship. Herein, a simple, efficient, and inexpensive purification method is implemented to reduce impurities in SCW and expose the morphology of nanosheets therein. Furthermore, HF is used to modulate the abundant native O in SCW after thermodynamic and kinetic considerations, realizing the mechanical support for the internal Si in the form of an amorphous SiO2 shell. Afterward, SCNS@SiO2 -2.5 with a 1.0nm thick SiO2 shell exhibits a reversible capacity of 1583.3 mAhg-1 after 200 cycles at 0.8 Ag-1 . Ultimately, the molecular dynamics simulations profoundly reveal that the amorphous SiO2 shell is transformed into the extremely ductile Lix SiOy shell to ditch stress and relieve strain during the lithiation/delithiation process.

The Role of Dual-Mobility Components in Total Hip Arthroplasty.

Dual mobility (DM) refers to a now widely available option for total hip articulation. DM implants feature a small inner head, a hard bearing, that connects via a taper fit onto the femoral trunnion. This head freely rotates but is encased inside a larger, outer polyethylene head that articulates with a smooth acetabular component. DM acetabular components are available in the form of a monoblock shell or as a liner that is impacted into a modular shell, providing a metal articulation for the polyethylene outer head. DM is designed to increase hip stability by providing the arthroplasty construct with a higher jump distance, head-to-neck ratio, and range of motion prior to impingement. The use of DM in total hip arthroplasty continues to increase in the United States for both primary and revision arthroplasty. Surgeons should be aware of the potential benefits and pitfalls. Long-term data are lacking, especially for modular DM implants. Points of concern include a potential for accelerated polyethylene wear, intraprosthetic dislocation, and modular backside fretting corrosion.

CEVİZ KABUĞUNUN DOĞAL BİYOSORBENT OLARAK ÇİNKO GİDERİMİNDE KULLANILMASININ ARAŞTIRILMASI

Heavy metal contamination is a primary concern worldwide and it is discharged from the industrial wastewater to a large amount of heavy metal receiving environments. In recent years, the effective use of agricultural by-products is definitely a major challenge in waste management. The fact that agricultural residues are more easily obtained and cheaper than commercial adsorbents makes it attractive. In this study, removal of zinc from industrial wastewater using natural and thermally modified (biochar) walnut shells as biosorbent was investigated. It was tried to remove zinc in aqueous solutions with different concentrations by using walnut shells at different rates. The effects of initial concentration, contact time, adsorbent dosage. In addition, adsorption isotherms and kinetics were also studied. With the modified form of the walnut shell, up to 98% zinc removal efficiency was obtained. Also, adsorption was observed to be consistent with pseudo-second kinetics and Freundlich isotherm. The results showed that the modified walnut shell in zinc removal was a potential adsorbent. The adsorption of zinc, onto walnut shells was found to fit Freundlich isotherm. The results obtained in the tests with wastewater showed the potential use of walnut shells for the removal of zinc.

Trifling with Catastrophe in King Lear

Abstract: King Lear 's characters call upon spherical objects both big and small to make sense of and give order to their world. Yet the play insists repeatedly that this reflex is limited, and even catastrophic. King Lear dramatizes the vanishing of all forms of protective shells, delivering us in act IV, scene vi to a Dover Cliff that is neither Dover nor Cliff. But at Dover Cliff, King Lear posits a different relationship to the spheres. Thinking through Peter Sloterdijk's "Spherology," Isabelle Stengers's "Cosmopolitical Proposal," and Edgar's stage trick or "trif[ling]," we might see King Lear situating an alternative way of living in catastrophic times—not imposed from above but felt from below, where one might bear "free and patient thoughts" if only for a trifling amount of time.

FORM-FINDING ANALYSIS OF HANGING MEMBRANE USING HORIZONTAL MEMBRANE STRESS DISTRIBUTION BY FINITE ELEMENT STRESS ANALYSIS

This paper proposes a simple method to obtain equilibrium membrane forms under the self-weight. The horizontal component of the membrane forces determined by the finite element analysis of an initial shell form is given as the known membrane stress distribution in the form-finding analysis. The form of the hanging membrane can be obtained by modifying the nodal z coordinates to be in equilibrium for the self-weight while maintaining the horizontal membrane stress distribution. Several numerical examples are presented to demonstrate the effectiveness of the proposed method.

Strategi Model Bisnis Startup Pupuk Berbasis Inovasi Limbah Ternak dan Cangkang Telur di Kabupaten Jember

The scarcity of fertilizers provides an opportunity for startup businesses to provide alternative organic fertilizers. PTC Organic is one of the pioneering business startups in producing alternative fertilizers that utilize livestock waste as the main ingredient in the form of egg shells, chicken bones, and beef bones that involve a series of processes so that they become available nutrients for plants. The research method used is descriptive-analytic using the Bussiness Model Canvas (BMC) method and SWOT analysis. The objectives of this research are 1) to map out the current PTC Organic business model using BMC, (2) to develop alternative business development strategies using the SWOT method. Internal and external factors include seven aspects of internal factors (Product, Price, Promotion, Business Location, Process, People, and Physical Evidence) and four aspects of external factors (Industrial Competitors, Suppliers, New Entrants, and Buyers). The results obtained are the position of Organic PTC is very profitable, namely in Quadrant I (0.3, 0.22). So anaggressive strategy in creating innovation and product development is necessary for the sustainability of PTC Organic's business.

Interactive Exploration of Tension-Compression Mixed Shells

Achieving a pure-compression stress state is considered central to the form-finding of shell structures. However, the pure-compression assumption restricts the geometry of the structure's plan in that any free boundary edges cannot bulge outward. Allowing both tension and compression is essential so that overhanging leaves can stretch out toward the sky. When performing tension-compression mixed form-finding, a problem with boundary condition (BC) compatibility arises. Since the form-finding equation is hyperbolic, boundary information propagates along the asymptotic lines of the stress function. If conflicting BC data is prescribed at either end of an asymptotic line, the problem becomes ill-posed. This requires a user of a form-finding method to know the solution in advance. By contrast, pure-tension or pure-compression problems are elliptic and always give solutions under any BCs sufficient to restrain rigid motion. To solve the form-finding problem for tension-compression mixed shells, we focus on the Airy's stress function, which describes the stress field in a shell. Rather than taking the stress function as given, we instead treat both the stress function and the shell as unknowns. This doubles the solution variables, turning the problem to one that has an infinity of different solutions. By enforcing equilibrium in the shell interior and prescribing the correct matching pairs of BCs to both the stress function and the shell, a stress function and shell can be simultaneously found such that equilibrium is satisfied everywhere in the shell interior and thus automatically has compatible BCs by construction. The problem of a potentially over-constrained form-finding is thus avoided by expanding the solution space and creating an under-determined problem. By varying inputs and repeatedly searching for stress function-shell pairs that fall within the solution space, a user is allowed to interactively explore the possible forms of tension-compression mixed shells under the given plan of the shell.

Perceptual evaluation of stadium façades

The study aims to evaluate 16 stadiums having different façade features in a comparative manner from a perceptual point of view. Therefore, the 16 stadiums constructed between 2011 and 2021 in Turkey were classified according to their facade and roof, shell forms and shell colors. The semantic differentiation scale consisting of adjective pairs of likability, complexity, impressiveness, familiarity and environmental compatibility that were found valid and reliable in previous studies was used to evaluate the selected stadiums. The means and standard deviations values were determined. Thereafter, the One-Way Analysis of Variance method was used in order to examine the impact of variables like gender and profession. The study concluded that stadiums with a circular shape and a neutral color whose covers are separete from façade, are more popular and evaluated more positively. Besides, women have a more negative approach than men and architects have a more positive approach than lay-persons (not-architect).

Full Mitochondrial Genomes Reveal Species Differences between the Venerid Clams Ruditapes philippinarum and R. variegatus.

In natural sea areas along the coast of China, venerid clams Ruditapes philippinarum and R. variegatus exhibit similar adult shell forms and are especially difficult to distinguish as spat and juveniles. This study used comparative mitochondrial genome analysis to reveal differences between these species. The results showed that: (1) the mitochondrial genomes of R. philippinarum and R. variegatus share a large number of similar gene clusters arranged in consistent order, yet they also display noncommon genes, with both gene rearrangements and random losses found; (2) the 13 protein-coding genes in R. philippinarum as well as two-fold and four-fold degenerate sites in R. variegatus have an evident AT bias; (3) the Ka/Ks ratio of the mitochondrial ATP8 gene was significantly higher in R. philippinarum than in R. variegatus, and an analysis of selection pressure revealed that the mitochondrial NADH dehydrogenase subunit 2 gene and NADH dehydrogenase subunit 6 gene of R. variegatus were under great selective pressure during its evolution; and finally, (4) the two species clustered into one branch on a phylogenetic tree, further affirming their phylogenetic closeness. Based on these results, we speculate that the species differences between R. variegatus and R. philippinarum are largely attributable to adaptive evolution to the environment. The present findings provide a reference for the development of germplasm identification.

Performance bounds of magnetic traps for neutral particles

Knowledge of the fundamental limitations on a magnetic trap for neutral particles is of paramount interest to designers as it allows for the rapid assessment of the feasibility of specific trap requirements or the quality of a given design. In this paper, performance limitations are defined for convexity of magnetic trapping potential and bias field using a local approximation in the trapping center. As an example, the fundamental bounds are computed for current supporting regions in the form of a spherical shell, a cylindrical region, and a box. A Pareto-optimal set considering both objectives is found and compared with known designs of the Baseball trap and Ioffe-Pritchard trap. The comparison reveals a significant gap in the performance of classical trap designs from the fundamental limitations. This indicates a possibility of improved trap designs and modern techniques of shape synthesis are applied in order to prove their existence. The topologically optimized traps perform almost two times better as compared to conventional designs. Last, but not least, the developed framework might serve as a prototype for the formulation of fundamental limitations on plasma confinement in a wider sense.

Nonlinear dynamic analisys of reservoir shell with modelled shape imperfections

The nonlinear dynamic analysis of imperfect reservoir shell with a variable thickness of wall under pressure was executed. The finite-element model of reservoir in the form of a cylindrical shell in the software NASTRAN was built. The shell wall in the form of the three-cornered finite-element net was presented. Shape imperfection as a lower buckling form of perfect shell (Buckling) was modelled. Value of amplitude of imperfection was set proportionally to a minimum thickness of shell wall. The limits on the radial and tangential displacements of top edge nodes were entered, the nodes of lower edge were fastened. Excitation as external pressure, which linearly depended on time and uniform distributed on all shell elements was presented. The modal analysis of shell with modelled shape imperfections by using computational procedure of task on natural vibrations (Normal Modes) by the Lanczos method was executed. The nonlinear dynamic analysis (Nonlinear Direct Transient) of imperfect reservoir shell under pressure by N’yumark method was executed. Influence of amplitude of modelled imperfection on the shell stress-strain for different time intervals of excitation, the conditionally critical values of dynamic loading and corresponding of shell deformation forms were investigated.
 It was discovered that a modelled shell shape imperfection as a lower buckling form of perfect shell under static pressure in the dynamic analysis of shell under the same type of the loading was effeсtive. Influence of modelled shape imperfections amplitude on the stress-strain state of shell for different time interval of excitation, the conditionally critical values of dynamic loading and appropriate forms of shell deformation was considerable. Presented imperfection model in the modal analysis of shell was not effective. The increase of amplitude of shell imperfection led to insignificant decrease of natural frequencies and amplitudes of appropriate natural forms with the same amount of the semiwaves in the circular direction. In our opinion presented model of shell shape imperfection can be effective in the modal analysis of shell with the stress-strain state from the previous action of static pressure and for the estimation of design reliability of reservoir shell in the case of the dynamic loadings using the Bolotin probabilistic approach.

The numerical analysis of the melting process in a modified shell-and-tube phase change material heat storage system

Thermal energy storage plays a major role in applying thermal energy sources such as waste heat and solar energy. As an efficient storage technique, the development of latent heat storage systems is a key factor for the successful application of thermal energy. This work presents thermal characteristics of a shell-and-tube phase change material (PCM) latent energy storage system with shell and tube forms of octagonal and three-lobe, respectively. The nano-enhanced paraffin wax was employed PCM, and the transient performance of the system was examined using the enthalpy-porosity method. The PCM temperature, melted fraction, and the Nusselt and Bejan numbers were adopted as system evaluation indexes, and sensitivity analysis was made to unveil the effect of copper nanoparticle (NP) concentration, the tube orientation angle and the eccentricity on system performance. The obtained results demonstrate that between the studied parameters, altering the eccentricity has the most effect on system characteristics; in the case of the above-located tube (denoted by case1), the melting time was reduced by 62 % compared to the base case. Changing the tube inclination angle and NP concentration does not show a significant effect on profiles of PCM temperature and melted fraction and mainly affect the Be number; using the case of 60° tube inclination angle and NP concentration of 4 % shows a slight improvement of temperature and melted fraction and reduces the average Be number.

Circular Economy Policy of Shrimp Waste as an Effort to Implement Green Economy

This study aims at determining the conditions and characteristics of shrimp waste, the economic value of the potential for shrimp waste, as well as the policy direction for implementing the Circular Economy of Shrimp Waste as a Green Economy Alternative in the Bulak Banteng Kenjeran Coastal Area, Surabaya City. The research method used is descriptive qualitative and quantitative with the process hierarchy analysis technique (AHP). The data collection method was carried out by distributing questionnaires and in-depth interviews with selected respondents. The results showed that the characteristics of shrimp waste in the form of shrimp heads and shells were still not used for economic value activities, and people dumped them in gutters around homes and at sea. The priority policy directions that can be applied to the Circular Economy of Shrimp Waste as an Alternative to a Green Economy are; 1) providing innovation and technology for economic-based shrimp waste processing with a total CR (consistency ratio) value of 1.878; 2) to improve environmental health by not disposing of shrimp waste around the house, the total value of CR is 1.127; and, 3) the government provides a shrimp processing industry for fishermen with a total CR value of 0.094. Each policy priority can be carried out in synergy so that shrimp waste can be handled properly.

Interface‐Tailored Relaxor Ferroelectric Nanocomposites with Ultrahigh‐Insulation Shell of Fluorinated Aromatic Polythiourea for High‐Capacitance Energy Storage Applications

AbstractThe strategy of interface engineering plays a prominent role in obtaining desirable dielectric performance of polymer nanocomposites. In this study, ultrahigh‐insulation BaTiO3@fluorinated aromatic polythiourea (BT@ArPFTU) nanoparticles (NPs), which are successfully synthesized via microwave‐initiated polymerization, are served as novel nanofillers to prepare poly(vinylidenefluoride‐trifluoroethylenechlorotrifuoroethylene)‐based (P(VDF‐TrFE‐CTFE)‐based) nanocomposites for capacitor applications. The ArPFTU coating shell forms a strong interface with 30‐nm thickness between BT and the matrix. It not only contributes to the suppression of current density at the interfaces, the regulation of interfacial charge distribution and tolerating high electric‐field strength, but also favors the improvement in dielectric constant and electric polarization due to interfacial polarization, as confirmed by finite element simulations and experimental results. In addition, the direct observation of electric‐polarization enhancement at the interfaces in the P(VDF‐TrFE‐CTFE)/BT@ArPFTU nanocomposites is well probed by piezoelectric force microscopy. Remarkably, with small loading of BT@ArPFTU NPs, relaxor ferroelectric nanocomposites display an unprecedented discharged energy density of 23.1 J cm−3 and the charge–discharge efficiency of 65%, which is much larger than that of other types of BT‐based polymer nanocomposites and commercial biaxially oriented polypropylene of 0.71 J cm−3. This systematic study further paves a new avenue to design high‐performance polymer nanocomposites by interfacial architecture for capacitor application.

Characteristics of Nanochitosan from Soft Shell Crab Culture Waste in TarakanUsing The Ionic Gelation Method

Crab that is undergoing a molting process produces solid waste in the form of shells that can disturb the environment. One of the appropriate technologies that can be utilized in dealing with this waste is the manufacture of nanochitosan. The purpose of this study was to obtain nano-sized chitosan from soft shell crab culture waste by determining the quality of chitosan through analysis of water content, ash, nitrogen, Fourier Transform InfraRed (FTIR) and Particle Size Analyzer (PSA). The material used in this research is crab shells from soft shell crab culture waste. The method used in this research is descriptive quantitative. The results showed that the yield of chitosan produced was 4.67%. The quality of chitosan produced showed 8% water content, 1.5% ash and 4.83% nitrogen. In the FTIR spectra of nanochitosan powder, peaks appear which confirm the bond in chitosan, while in nanochitosan gel it is dominated by the absorption band of H-O which indicates the presence of water as a solvent. The value of the degree of deacetylation of the chitosan nanoparticles produced was 78.43%. The particle size of chitosan by ionic gelation method was 468.1±21.63 nm. The high speed of the magnetic stirrer is able to reduce the chitosan to a stable nano size and prevent agglomeration.

Review: Sculpture on a Grand Scale: Jack Christiansen’s Thin Shell Modernism

Review: <i>Sculpture on a Grand Scale: Jack Christiansen’s Thin Shell Modernism</i>

An integrated form-finding and automated fabrication approach for exploring sustainable shell structures

Latest advances in computational design and automated fabrication provide opportunities for form-finding and precise development of shell structures in an integrated design to fabrication context. Implementation of these techniques cannot be completed without considering the negative effect of construction in the environment and the urgent need for environmental impact reduction through reusability and recyclability. This paper deepens into this direction by presenting a form-finding/automated fabrication approach of shell forms in combination with a recycle material implementation. The process starts by examining form-finding possibilities of funicular forms by producing a series of case studies based on a number of controlled parameters, physical attributes and static performance criteria. Then, an alternative use of construction materials is presented, in order to achieve sustainable properties, and adequate static performance of both, the overall structure and the individual structural components. In order to achieve this, cylindrical samples of different recycle material combinations are produced, tested under compression and their implementation is discussed. The suggested integrated form-finding to automated fabrication approach offers the opportunity for a holistic sustainable approach towards shell structures development, aiming at shape and performance viability through the selection of recycle materials.