Types Of Shells Research Articles

Optimization of Placuna Placenta Collagen Serum on Adolescent Skin

Placuna placenta has a unique character among other types of shells due to its thin and wide shell shape. The protein contained in Placuna placenta is 71% which can be used as skin nutrition. Its application to the skin can be done through collagen serum preparations. The aim of this study was to optimize the Placuna Placenta serum collagen in adolescent skin. The current research was done through an experimental study of a post-test control design in the form of a post-only controlled group design with five treatment groups with each group consisting of five skins of adolescent arms. The negative control group was given a serum base that was applied to the skin of the adolescent arm. The positive control group was given serum product x®. The test group was given Placuna Placenta shell collagen serum with the concentrations of 10%, 15% and 20%. The results showed that collagen serum can irritate the skin. In addition, the optimization of the serum collagen concentration of Placuna Placenta in adolescent skin is at a concentration of 15%. It can be summed up that optimizing the use of collagen serum on adolescent skin is a challenge in the formulation because it is beneficial for adolescent skin nutrition.

Improvement of Impact Energy Absorption of Curved Thin Chopped Tape CFRP Shell by Adding Submicron Glass Fiber into Matrix

The effect of the addition of submicron glass fibers into the matrix of curved thin shell of CFRP in thickness direction on the energy absorption during out-of-plane impact was investigated with four types of specimens. Four types of CFRP shells were prepared in which each shape was: (a) flat plate (b) half-cylinder (c) low wide elliptical half-cylinder (d) high wide elliptical half-cylinder. The results showed that improvement of impact energy absorption was obtained for thin shell specimen with curved geometry as well as that for flat plate by adding submicron glass fiber into the matrix. This study found that design with half-cylinder CFRP shell is rather effective to utilize the result of modification with submicron glass fibers previously added into the matrix where the impact energy absorption was improved.

On the diagnostic features of the gas-discharge visualization for the assessment of medicines

The therapeutic efficiency of medicines containing the same active ingredient depends on the production technology, as well as the excipients included in the tablet and the type of shell. In this work, we consider some of the possibilities of using the gas-discharge visualization method based on the phenomenon of channeling electrons through a liquid medium to study aqueous solutions of medicines. The study was carried out on the example of the passage of kilovolt electrons through drops of solutions of the beta-blocker bisoprolol, produced by various pharmacological companies. We studied bisoprolol preparations without excipients and bisoprolol preparations with excipients. The obtained differences in the characteristics of the gas-discharge luminescence for the studied medicines open up prospects for assessing the quality and pharmacological efficiency of medicines, and, subsequently, for the individualization of medicines therapy.

Thermally vibrational analyses of functionally graded graphene nanoplatelets reinforced funnel shells with different complex shapes surrounded by elastic foundation

The paper investigates nonlinear dynamic behavior of functionally grade graphene nanoplatelets reinforced (FG-GPLRC) shell with radius as a high-order function using the classical thin shell theory (CTST) and the Von Karman-Donnell geometrical nonlinearity assumption. Different from cylindrical or conical shells, variations of radius are formulated as quadratic or/and cubic functions, generating three types of funnel shells. To verify the computation, the fundamental frequencies are compared with the previous literatures and Finite Element Analysis. The effects of various parameters including geometries, materials, temperature are considered. Obtained results of the shell promisingly make a significant contribution to various fields of engineering.

Design and Performance Prediction of a Compact MmNi4.6Al0.4 based Hydrogen Storage System

The present work is focused on the design and numerical prediction of hydrogen storage performance of a compact MmNi4.6Al0.4 based hydrogen storage unit. Two types of shell and tube reactors capable of holding the same amount of metal alloy are compared for hydriding performance using a 3-D numerical model realized in COMSOL Multiphysics 5.3. The first configuration is an Embedded Cooling Tube (ECT) model where the alloy is contained in the shell and Heat Transfer Fluid (HTF) flows through the tubes; whereas in the second configuration, the alloy is contained in the tubes, which is termed as tube bundle (TB), and HTF flows over the tube bundle inside a shell. The TB configuration showed marginally better initial hydriding rate as compared to the ECT configuration and yielded 1.17 times higher alloy-to-container weight ratio. Based on the TB configuration design methodology, a metal hydride based hydrogen storage unit of 100 kg alloy capacity was proposed, where 4 tube bundle modules of 25 kg alloy capacity each could be arranged in parallel. A parametric study was conducted on the 25 kg reactor module to analyse the effects of various operating parameters viz. supply pressure, HTF temperature and convective heat transfer coefficient on hydrogen storage behaviour. Numerical study predicted that the MH module could store 307.5 g of hydrogen in 600 s, when subjected to 30 bar supply pressure at 298 K HTF temperature, whereas 292.5 g of hydrogen could be discharged at 1 bar, in 1000s, at 303 K HTF temperature.

Can relic shells be an effective settlement substrate for oyster reef restoration?

Acute storms (e.g. hurricanes) are major stressors to eastern oysters (Crassostrea virginica) through burying oysters and settlement substrate. Subsequently, managers use many restoration efforts, of which one approach is bag‐less dredging. This resurfaces relic shells as settlement substrate; however, buried shells turn black in anoxic sediments potentially influencing spat settlement. This study compared three shell types: sun‐cured white shell utilized in oyster reef restoration and two representative black shell types for bag‐less dredging. Settlement was significantly higher on sun‐cured white shell suggesting that restoration activities resurfacing black shells may not provide suitable substrate and alternative methods of providing substrate should be prioritized.

Pyrolysis of walnut shell residues in a fixed bed reactor: Effects of process parameters, chemical and functional properties of bio-oil

In the present work the products and characteristics of bio-yields obtained from pyrolysis of different types of walnut shells (WS) by using a fixed bed pyrolyzer. The different walnut shells considered are paper (PSW), thin (TSW), medium (MSW) and hard (HSW) shelled walnut. The biomass samples were pyrolyzed at various temperatures, particle sizes, heating and sweep gas flow rates. The results revealed that the maximum bio-oil 44.7, biochar 37.6 and gas 40.4 wt% yields have been obtained for HSW, MSW and HSW at a pyrolysis temperature of 550, 375 and 750 °C respectively at heating rate 0.33 K/sec, particle size 0.5–1.5 mm with swept gas flow rate 1.6 × 10−6 m3/s. The higher heating value (HHV) of bio-oil obtained from different walnut shells are ranged from 26 to 27.3 MJ/kg. Comprehensive physiochemical characteristics such as density, viscosity, flash point, pour point and water content of bio-oils have been obtained. Chemical composition analysis of bio-oils revealed that the pyrolytic bio-oil composition is predominated by oxygenated compounds such as carbonyl, methoxy, phenols and carboxyl groups determined by GC-MS, FTIR, 1H NMR and 13C NMR. The pyrolysis gas mainly contained CH4 CO, H2, CO2, and light hydrocarbons. Based on these results and structural analysis of the bio-oil, it can be concluded that the bio-oil obtained from WS may be used as a feedstock for furnaces, as a fuel, as a lubricant after modifications and value-added products via pyrolysis.

Dynamic analysis of coupled composite laminated shells with elastic boundary condition using a domain decomposition method

In this paper, the free and forced vibration behavior of coupled composite laminated shell are investigated by using a domain decomposition method under the elastic boundary condition. The coupled shell structure is combined in the form of a double curved shell-cylindrical shell-double curved shell, and the double curved shells at both ends are combined with the cylindrical shell upside down (figure 1). The double curved shell contains the elliptical, paraboloidal and hyperbolical shells. multi-segment partitioning technique is employed to establish the theoretical model based on the first-order shear deformation theory (FSDT). Regardless of the shell types and boundary conditions, the displacement functions of each shell are expended by the orthogonal ultraspherical polynomials in the meridional direction, and by the standard Fourier series in the circumferential direction. The boundary and continue conditions are generalized by the artificial spring technology. The convergence study and numerical comparison with finite element method (FEM) demonstrates that the proposed method has good reliability and accuracy to analyze the dynamic characteristics of the coupled composite laminated shell. The effects of material properties, geometric dimension, boundary condition and external force on the coupled composite laminated shell structure are proposed with some numerical results.

X-Ray Photoelectron Spectroscopy on Microbial Cell Surfaces: A Forgotten Method for the Characterization of Microorganisms Encapsulated With Surface-Engineered Shells.

Encapsulation of single microbial cells by surface-engineered shells has great potential for the protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV light, extreme pH values, and antimicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors, and the human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon microbial growth, ultimately breaking a shell. Therewith, the danger of creating a “super-bug,” resistant to all known antimicrobial measures does not exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms, and X-ray diffraction. It is amazing that X-ray Photoelectron Spectroscopy (XPS) is forgotten as a method to characterize encapsulated yeasts and bacteria. XPS was introduced several decades ago to characterize the elemental composition of microbial cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be easily pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in microbial cell surfaces. Models exist to transform these compositions into well-known, biochemical cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic acid, peptidoglycan, and hydrocarbon like components. Moreover, elemental surface compositions of many different microbial strains and species in freeze-dried conditions, related with zeta potentials of microbial cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of microbial cell surface XPS. Despite the merits of microbial cell surface XPS, XPS has seldom been applied to characterize the many different types of surface-engineered shells around yeasts and bacteria currently described in the literature. In this review, we aim to advocate the use of XPS as a forgotten method for microbial cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.

Preparation and Characterization of Core-Shell Structure Hard Carbon/Si-Carbon Composites with Multiple Shell Structures as Anode Materials for Lithium-Ion Batteries

Novel core-shell structure hard carbon/Si-carbon composites are prepared, and their electrochemical performances as an anode material for lithium-ion batteries are reported. Three different types of shell coating are applied using Si-carbon, Si-carbon black-carbon and Si-carbon black-carbon/graphite nanosheets. It appears that the use of n-Si/carbon black/carbon composite particles in place of n-Si for the shell coating is of great importance to achieve enhanced electrochemical performances from the core-shell composite samples, and additional wrapping with graphite nanosheets leads to a more stable cycle performance of the core-shell composites.

On the elastic buckling of cross-ply composite closed cylindrical shell under hydrostatic pressure

This paper focuses on the elastic buckling of cross-ply composite closed cylindrical shell subjected to hydrostatic pressure. The analytical model for buckling of composite cylindrical shell is derived by using the First Order Shear Deformation Theory (FOSDT) and considering the pressure stiffness. Several types of shells including thin, thick, long, and short shells are investigated. Two composite materials i.e. Carbon/Epoxy and Glass/Epoxy and several layup configurations are employed. The results of the derived FOSDT-based model are compared with those obtained from a Shell Buckling Equation (SBE) used in earlier studies and the Classical Shell Theory (CST). For verification, the results of the derived FOSDT-based model are compared with the results found in literature and also with the results obtained from finite element analysis. The difference among the results of the SBE and FOSDT, and the CST and FOSDT increases with the increase of the thickness in the case of all layup configurations and materials. For thin shells, the difference between the results of the CST and FOSDT almost vanishes, while for thin and large shells, the difference between the results of the SBE and FOSDT is still significant.

Numerical investigation on the shell and tube heat exchanger with baffle leakage zones blocked

A novel type of shell and tube heat exchanger with modified fold helical baffles and twisted oblate tubes (STHXsFBTB) is proposed to seal the leakage areas in the shell center of the shell and tube heat exchanger with fold helical baffles (STHXsFB). The thermal and hydraulic properties of STHXsFB and STHXsFBTB for water chiller systems are investigated by numerical simulation. The influences of the configuration factors (screw pitch and tube diameter ratio, length width ratio and cutting ratio) on the thermal and hydraulic properties of STHXsFBTB are studied. Compared with STHXsFB, the heat transfer coefficient (h) of STHXsFBTB increases by 3.88%–8.05%, while the pressure loss (△P) decreases by 6.50%–7.38%, and the comprehensive heat transfer performance (Nu·f−1/3) increases by 6.38%–10.35%. Moreover, as screw pitch and tube diameter ratio, length width ratio and cutting ratio increase, both h and Nu·f−1/3 decrease. The influences of the length-width ratio and the cutting ratio on thermal and hydraulic properties of STHXsFBTB are tremendous, while the screw pitch and tube diameter ratio has a negligible effect. When the screw pitch and tube diameter ratio is 10, the length width ratio is 1.5 and cutting ratio is 0.35, the optimum configuration of STHXsFBTB is obtained.

Numerical and Experimental Investigation on Post-buckling Behavior of Stiffened Cylindrical Shells with Cutout subject to Uniform Axial Compression

In this paper, post buckling behavior of thin steel and aluminum cylindrical shells with rectangular cutouts under axial loading was studied experimentally and also using the finite element method. Riks method is used for analyzing the cylindrical shells. The effect of longitudinal and circumferential stiffeners (ribs and stringer) was studied on the buckling load and the post buckling behavior as the stiffeners used individually and in combination with each other. It was shown that by adding stringer, the buckling load improves and the rib has a positive effect on the post buckling behavior of the structure. Some tests were performed by ZwickRoell tensile/compression testing machine and it was carried out for both types of steel and aluminum shells with and without stiffeners. Comparing the experimental results with the FEA results shows good agreement. Nonlinear analysis of cylindrical steel and aluminum shells with cutout have demonstrated that, in some cases, a local buckling called snap-back can be seen in the load-displacement path. Snap-back which is a decrease in the amount of both load and displacement indicates this local buckling. This phenomenon is because of appearing mode shapes sequentially during the numerical buckling analysis of shells. Although these local buckling happened, the structure is still endured the higher loads.

Substrate selection for oyster reef restoration: Differences in oyster settlement and recruitment on fresh and old oyster shells

The lab and field experiments of 2019 examined the effects of oyster shell type and biofilm on oyster settlement and recruitment. Results from the lab experiment indicated that both shell type and biofilm significantly affected the densities of settled oysters. There were higher settlement and recruitment of oyster spats on the fresh oyster shell with biofilm than on the old oyster shell with biofilm (<italic>P</italic><0.05), but differences in the densities of settled spat were not evident between these two shells without biofilm (<italic>P</italic>>0.05). Biofilm significantly increased the attractiveness of the fresh shell to oyster larvae (<italic>P</italic><0.05), but had little influence on the old shell (<italic>P</italic>>0.05). The field experiment of 2019 found the contrast patterns. Oyster shell type had no influence on the densities of settled oysters, while biofilm significantly increased the biological acceptability of the old shell. The field experiment of 2020 examined the effects of oyster shell and tidal zone on the densities of settled oysters and barnacles. Two-way ANOVA found that shell types significantly affected the densities of settled oyster spats, while tidal zone had little effect on oyster settlement. At each of the two tidal levels (0.6 m and 1.1 m), there were consistently greater densities of settled oyster spats on the fresh shell than on the old shell on the 15 d, 45 d and 70 d(<italic>P</italic><0.05). Results from two-way ANOVA demonstrated that neither shell types or biofilm had significant effect on the shell height of settled oysters. Settled spats measured on 45 d and 70 d had significantly greater size than those on 15 d(<italic>P</italic><0.05). Results from two-way ANOVA found that oyster shell had no influence on barnacle settlement, while tidal zone significantly affected barnacle settlement. Higher densities of settled barnacles were found on the fresh shell than on the old shell in the 0.6 m tidal zone on 15 d(<italic>P</italic><0.05), whereas the difference disappeared at each of the two tidal levels on the 45 d and 70 d (<italic>P</italic>>0.05). The study indicated that there were generally higher oyster settlement and recruitment on the fresh shell than on the old shell, and the evident differences extended to the recruitment season. Therefore, it concluded that the fresh shell were more preferable substrate for oyster reef restoration than the old shell.

Performance evaluation of biomass pretreated by demineralization and torrefaction for ash deposition and PM emissions in the combustion experiments

Biomass combustion is a promising method in combustion facilities to reduce CO2 emissions. Biomass fuel has unfavorable characteristics, such as low temperature ash minerals and high particulate matter (PM) emission in the combustion facility, which influences operation and creates environmental issues. In this work, different types of empty fruit bunch (EFB) and palm kernel shell (PKS) biomass samples, such as raw biomass, demineralized biomass, and its biomass pretreated by torrefaction were studied to identify their char combustion characteristics by thermogravimetric analysis (TGA) and their ash deposition behaviors and PM emissions in a drop tube furnace (DTF) experiment. Regarding the char combustion characteristic results obtained by TGA, demineralization pretreatment did not clearly influence the char combustion reactivity compared to that of raw biomass, but torrefaction pretreatment lowered the char combustion reactivity at low temperatures. In the DTF experiments, torrefaction pretreatment led to increasing ash deposition and PM emissions during biomass combustion. However, demineralization pretreatment clearly lowered the amount of ash deposition and PM emissions because potassium (K), chlorine (Cl), and sulfur (S) were significantly removed by demineralization pretreatment. In particular, scanning electron microscopy with dispersive X-ray spectroscopy (SEM-EDX) analysis results showed that the demineralized biomass samples having low K, Cl, and S components emitted relatively large PM compared to untreated biomass. Therefore, demineralization pretreatment might be a good method to produce cleaner biomass fuel.

Past testate amoeba communities in landslide mountain fens (Polish Carpathians): The relationship between shell types and sediment

Landslide mountain fens formed in landslide depressions are dynamic environments as their development is disturbed by a number of factors, for example, landslides, slopewash, and surface run-off. These processes lead to the accumulation of mineral material and wood in peat. Disturbed peatlands are interesting archives of past environmental changes, but they may be challenging for providing biotic proxy-based quantitative reconstructions. Here we investigate long-term changes in testate amoeba communities from two landslide mountain fens – so far an overlooked habitat for testate amoeba investigations. Our results show that abundances of testate amoebae are extremely low in this type of peatlands, therefore not suitable for providing quantitative depth-to-water table reconstructions. However, frequent shifts of dominant testate amoeba species reflect dynamic lithological situation of the studied fens. We observed that high and stable mineral matter input into the peatlands was associated with high abundances of species producing agglutinated (xenosomic) as well as idiosomic shells which prevailed in the testate amoeba communities in both analyzed profiles. This is the first study that explores testate amoebae of landslide mountain fens in such detail, providing novel information about microbial communities of these ecosystems.

Kinetic and thermodynamic analysis of thermo-oxidative degradation of seashell powders with different particle size fractions: compensation effect and iso-equilibrium phenomena

The issue of accumulated seashell waste has been increasingly addressed in the studies of its applicability as a secondary source of calcium carbonate. In this work, the mechanism of the thermo-oxidative degradation of two types of mollusk shells (Dosinia exoleta—DE and oyster Ostrea edulis—OE) was investigated using simultaneous thermal analysis. Physicochemical characterization of raw and calcined materials was performed by XRD and SEM techniques. Results show that increasing powder particle size and heating rate affect the degradation of investigated shells differently and have a significant contribution to released quantities of CO2. It was proposed that the calcination rate of DE powders is determined by the strain-induced collapse of CO2-deficient calcite at its interface with crystalline CaO rods-like structure, with simultaneous expulsion of CO2. A much higher CO2 concentration was identified during the degradation of OE powders, favoring the carbonation reaction and, consequently, increasing the temperature and activation energy of the investigated reaction. Under elevated CO2 concentration, the CaO aggregation step is enhanced by slower reaction kinetics at lower temperatures since both CO2 desorption and structural transformations are probably hindered. The proposed mechanism leads to a meaningful correlation between thermodynamic quantities (enthalpy–entropy compensation) in the form of an iso-kinetic relationship.

Progress on Modified Calcium Oxide Derived Waste-Shell Catalysts for Biodiesel Production

The dwindling of global petroleum deposits and worsening environmental issues have triggered researchers to find an alternative energy such as biodiesel. Biodiesel can be produced via transesterification of vegetable oil or animal fat with alcohol in the presence of a catalyst. A heterogeneous catalyst at an economical price has been studied widely for biodiesel production. It was noted that various types of natural waste shell are a potential calcium resource for generation of bio-based CaO, with comparable chemical characteristics, that greatly enhance the transesterification activity. However, CaO catalyzed transesterification is limited in its stability and studies have shown deterioration of catalytic reactivity when the catalyst is reused for several cycles. For this reason, different approaches are reviewed in the present study, which focuses on modification of waste-shell derived CaO based catalyst with the aim of better transesterification reactivity and high reusability of the catalyst for biodiesel production. The catalyst stability and leaching profile of the modified waste shell derived CaO is discussed. In addition, a critical discussion of the structure, composition of the waste shell, mechanism of CaO catalyzed reaction, recent progress in biodiesel reactor systems and challenges in the industrial sector are also included in this review.

Preliminary structural design for extraterrestrial buildings

The adventurous human nature had recently expanded to extraterrestrial habitation. Public billion-dollar companies such as SpaceX and Blue Origin are investing extra ordinary capitals in space exploration. Australian Space Agency had also joined the space competition in 2018 in a so-called Mars mission. Although might sound far reaching, the idea of building human habitats on Mars requires well evaluated engineering design in the first stage as the cost of transporting equipment and materials as light as a kilogram to another planet is a massive financial burden. Throughout this passage, the effect of gravity, atmospheric pressure, and radiation on extra terrestrial buildings will be discussed. Following that a cylindrical structure as the most stable type of shell against internal pressure will be analyzed.

The use of shells in the architecture of the concert halls

Abstract This paper deals with the use of the shells in the architecture of concert halls through research on the historical development of the concert building’s space. These elements are widely applied in civil engineering and architecture due to the good operational qualities, very rich spectrum of forms, the simplicity of production and its technical efficiency. The article considers two types of shells: conoid and truncated cone to choose the most optimal form for covering the concert hall.