Shell Surface Research Articles

Unraveling the role of Fe5C2 in CH4 formation during CO2 hydrogenation over hydrophobic iron catalysts

The production of value-added hydrocarbons by CO2 hydrogenation over iron (Fe) catalysts is an emerging platform reaction in CO2 utilization. However, CH4 forming in all hydrogenation reactions is undesirable. We focus on the role of Fe5C2 active species in CH4 formation during CO2 hydrogenation catalysis. Thus, Fe5C2 was manipulated by covering a hydrophobic shell to clarify the pathway of CH4 formation. By a combination of TPSR, in situ spectroscopies and DFT calculations, the variation in the mechanism of CH4 formation with the content of hydrophobic shell has been revealed. Meanwhile, the enhancement of H2O retention on the hydrophobic shell surface of Fe5C2 was found to inhibit the activation of CO2 by increasing energy barriers of C-C coupling reactions. Deep insights into the tunable role of Fe5C2 in the formation of CH4 can help for the further design of high performance catalysts for this reaction.

Imbricated shell sculpture in benthic bivalves.

Molluscan shells display a high diversity of external sculpture. Sculptural elements may be symmetrical, where both edges of an element are morphologically similar, or asymmetrical, where one edge is steeper than the other. Asymmetrical sculpture can be ratcheted, with the leading edges (those in the direction of locomotion or growth) less steep than the trailing edges, or imbricated (leading edges steeper than trailing edges). While the ratcheted sculpture is better known, the diversity of imbricated sculpture has remained largely unexplored. In a survey of extant benthic shell-bearing molluscs, we document imbricated sculpture primarily in epifaunal bivalves or on the exposed sectors of shells of semi-infaunal bivalves. Imbricated sculpture is particularly widespread in pteriomorphian bivalves, but it is absent in the subclade Mytiloidea as well as in highly mobile Pectinidae. It also occurs in many carditid bivalves (Archiheterodonta) and in phylogenetically scattered euheterodonts. In several infaunal bivalves including species of Cardites (Carditidae), Hecuba (Donacidae), and Chione (Veneridae), comarginal elements on the posterior sector are imbricated whereas anterior comarginal ridges are ratcheted. Imbricated sculpture in bivalves tends to be concentrated on the upper (left) valves of pectinids or on the posterior sector of both valves in archiheterodonts and euheterodonts. Imbricated sculpture is uncommon in gastropods, even in epifaunal species, but does occur in the collabral ridges in some Vasidae and a few other groups. Expression of imbricated sculpture does not depend on shell mineral composition or microstructure. The ecological distribution and within-shell pattern of expression of imbricated sculpture point to the likelihood that this type of asymmetrical sculpture is both widespread and potentially functional. Additionally, we present a potential methodology whereby shell sculpture categories (symmetrical, ratcheted, and imbricated) may be quantified by comparing the lengths of corresponding leading and trailing edges across the shell surface.

The Effect of Storage Periods on the Internal and External Quality Characteristics of White and Brown-Shell Table Eggs in Saudi Arabia

Background: The eggs of hens are an essential source of protein, a food that meets human needs and provides the body with amino acids, metallic elements and vitamins that promote its health. The research aims to study the influence of storage period and strain and the interaction between them on components and internal and external quality traits of commercially produced brown and white-shell eggs. Methods: A total of 180 eggs were randomly collected from both types. It was kept for 0, 15 and 30 days at temperatures ranging from 5±2°C to a humidity level of 60%. All eggs were broken to measure the egg coefficient, egg weight, egg weight loss and depth of the air chamber. shell thickness, shell density, shell cleanliness, shell surface area, shell weight relative to shell area unit, egg specific density, Haugh unit values, yolk color, presence of flesh and blood spots, white weight, shell weight, yolk weight, shell integrity, white weight percentage, percentage of shell weight, yolk weight ratio and yolk weight ratio. Result: White eggs weighed more than brown eggs and storage periods had a significant (P less than 0.05) effect on the Haugh unit, specific density, air chamber depth and shell thickness. It has a positive effect on shell density and shell weight for both brown and white-shelled eggs. The storage period also led to a significant increase in weight loss, a significant decrease in white, yolk and shell and significant changes in all parts of the egg because the shell color changed.

The structure of the eggshell and eggshell membranes of Crocodylus niloticus.

The macro- and microstructure, elemental composition, and crystallographic characteristics of the eggshell and eggshell membranes of the Crocodylus niloticus egg was investigated using optical and electron microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) and computerised tomography. The translucent ellipsoid egg is composed of two basic layers, the outer calcified layer referred to as the shell and an inner organic fibre layer, referred to as the shell membrane. The outer inorganic calcite shell is further divided into an external, palisade and mammillary layers with pore channels traversing the shell. The external layer is a thin layer of amorphous calcium and phosphorus, the underlying palisade layer consist of irregular wedge-shaped crystals composed calcite with traces of magnesium, sodium, sulphur and phosphorus. The crystals are mostly elongated, orientated perpendicular to the shell surface ending in cone-shaped knobs, which forms the inner mammillary layer. The elemental composition of the mammillae is like that of the palisade layer, but the crystal structure is much smaller and orientated randomly. The highest number of mammillae and shell pores are found at the equator of the egg, becoming fewer towards the egg poles. The shell thickness follows the same pattern, with the thickest area located at the equator. The eggshell membrane located right beneath and embedded in the mammillary layer of the shell; it is made up of unorganised fibre sheets roughly orientated at right angles to one another. Individual fibres consist of numerous smaller fibrils forming open channels that run longitudinally through the fibre.

Numerical simulation on hydrodynamic lubrication performance of bionic multi-scale composite textures inspired by surface patterns of subcrenata and clam shells

Inspired by the surface of shells in natural world, six bionic multi-scale composite surface textures were designed. Numerical simulation was carried out to investigate the mechanism for influences of the texture geometric parameters and service conditions on lubrication characteristics. The results revealed that the bionic surface enhanced the load-carrying capacity and reduced the friction coefficient. Groove combinations offered a better lubrication performance than wavy combinations. The texture geometric parameters showed significant influence on the frictional characteristics. For all texture shapes, the load-carrying capacity increased approximately linearly with the rotational speed and decreased with the water film thickness. The results would help guide effective texture design to improve the lubrication performance of axial piston pump friction pairs under marine environments.

The unique fibrilar to platy nano- and microstructure of twinned rotaliid foraminiferal shell calcite

Diversification of biocrystal arrangements, incorporation of biopolymers at many scale levels and hierarchical architectures are keys for biomaterial optimization. The planktonic rotaliid foraminifer Pulleniatina obliquiloculata displays in its shell a new kind of mesocrystal architecture. Shell formation starts with crystallization of a rhizopodial network, the primary organic sheet (POS). On one side of the POS, crystals consist of blocky domains of 1 μm. On the other side of the POS crystals have dendritic-fractal morphologies, interdigitate and reach sizes of tens of micrometers. The dendritic-fractal crystals are twinned. At the site of nucleation, twinned crystals consist of minute fibrils. With distance away from the nucleation-site, fibrils evolve to bundles of crystallographically well co-oriented nanofibrils and to, twinned, platy-blade-shaped crystals that seam outer shell surfaces. The morphological nanofibril axis is the crystallographic c-axis, both are perpendicular to shell vault. The nanofibrillar calcite is polysynthetically twinned according to the 60°/[100] (= m/{001}) twin law. We demonstrate for the twinned, fractal-dendritic, crystals formation at high supersaturation and growth through crystal competition. We show also that c-axis-alignment is already induced by biopolymers of the POS and is not simply a consequence of growth competition. We discuss determinants that lead to rotaliid calcite formation.

Greatly improvement of Cr(VI) reduction by introducing foreign electrons and suppressing oxidization toward the reductant decimeter-sized zero-valent iron plate

A large-sized zero-valent iron plate (LSZVIP) with excellent reaction efficiency and cycle performance for heavy-metal ion removal from wastewater is desirable. However, it has yet to be achieved due to its relatively low specific surface area and non-crystal oxide shells produced during treatment, preventing its core electrons from transporting to the shell surface for heavy-metal ion reduction. Therefore, we proposed a novel mechanism to address the challenges in this paper by earthing the iron plate and stirring the treated solution to trigger an insulator-to-metal transition in the non-crystal oxides shell, thereby removing the barrier to electron transport in the oxide shells. Furthermore, earthing of the iron plate allows electrons from the earth to participate in hexavalent chromium (Cr(VI)) reduction, thereby eliminating the production of oxide shells during the reduction. With the stirring and earthing strategy, an acceptable Cr(VI)-reduction performance is obtained over the decimeter-sized zero-valent iron plate (DSZVIP). The residence time of earthing DSZVIP in the 1st cycle is 25 min and 80 min in the 10th cycle by stirring at 350 rotations per minutes (rpm) to achieve 100% Cr(VI)-reduction. This study provides a novel and applicable method for treating heavy-metal wastewater on a large scale.

An Eco-Friendly Modification of a Walnut Shell Biosorbent for Increased Efficiency in Wastewater Treatment

Herein, we report the performance of some low-cost biosorbents developed by environment-friendly modification of walnut shells. Two types of biosorbents were prepared by ecological modification of walnut shell surfaces: (1) biosorbents obtained by hot water treatment (WSH2O) and (2) biosorbents produced by mercerization (WSNaOH). Different techniques were used to evaluate the morphological, elemental, and structural modification of the biosorbents, by comparison with raw materials. These characterization techniques involved scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis, and Fourier-transform infrared spectroscopy (FTIR). The biosorbents were employed for the removal of methylene blue (MB) and crystal violet (CV) cationic dyes (as model organic pollutants) from aqueous solutions. The kinetic adsorption data mainly followed the pseudo-first-order model. The maximum adsorption capacities of the produced biosorbents ranged from 102 to 110 mg/g and were observed at 330 K. Equilibrium data for adsorption were fitted to Langmuir and Freundlich isotherm models. The calculated values of thermodynamic parameters suggested that the investigated adsorption processes were exergonic (ΔG < 0) and exothermic (ΔH < 0). In addition, a possible valorization of the cost-effective and eco-friendly spent biosorbents was tested by performing secondary adsorption of the anionic dyes.

Electromagnetic alternators with composite amorphous alloy shell for improving characteristics

In this study, a magnetic casing encapsulating a generator is used to improve the electromagnetic and power characteristics of the generator. Two types of two-pole AC generators are proposed: one is a bare-bonded (NC) type and the other is an iron-based amorphous alloy material covering the generator casing. In this study, Fe-Si-B amorphous thin strips were annealed between 300 and 380 °C and soaked for 60 min to observe and analyze the structural changes and the evolution of properties under different temperature conditions. After the thin strip is annealed at 400 °C, α-Fe dendrites begin to appear, and at 450 °C, a large number of α-Fe dendrites are formed. The demagnetization rate of the permanent magnet area near the bottom of the pole piece is the highest for the generator with an amorphous alloy shell because the magnetic flux leakage from the side frame of the pole piece changes the magnetic flux path, thereby affecting the demagnetization performance. In this study, three amorphous alloys, HB1-M, HB1, and SA1, were used as the cladding permanent magnet generator shell, and annealing and non-annealing procedures were conducted to observe the influence on the magnetic power of the generator. The magnetic flux on the surface of the amorphous shell was measured by a magnetic fluxmeter. For experiments with an amorphous shell, the results show that the annealed center point magnetic flux densities were approximately HB1-M (15 mT), HB1 (12 mT), and SA1 (10 mT), and the marginal non-annealed amorphous thin strip could reach ∼7–5 mT. The measured generator harmonic component of SA1 is higher than the voltage and current harmonics, reflecting that the magnetization direction of the magnetic shell in the demagnetization region is covered by the magnetic flux density. Because of central flame annealing, the magnetic shell is paramagnetic, and it helps to reduce the noise by at least 5 dB. The generator current harmonic characteristic of the HB1-M material is smaller than that of the HB1 and SA1 materials. In this study, a composite amorphous material was used to cover the generator casing; it was verified that HB1-M + HB1 + SA1 has the lowest noise characteristics for the generator. The generator noise of the composited material (HB1-M + HB1 + SA1) can be reduced to below 69 dB, which is ∼7–9 dB lower than that of a single amorphous material.

A One-Year Systematic Study to Assess the Microbiological Profile in Oysters from a Commercial Harvesting Area in Portugal.

As filter-feeding animals farmed in water bodies exposed to anthropogenic influences, oysters can be both useful bioremediators and high-risk foodstuffs, considering that they are typically consumed raw. Understanding the dynamic of bacterial and viral load in Pacific oyster (Crassostrea gigas) tissues, hemolymph, outer shell surface biofilm, and farming water is therefore of great importance for microbiological risk assessment. A one-year survey of oysters collected from a class B production area (Canal de Mira, on the Portuguese western coast) revealed that these bivalve mollusks have a good depurating capacity with regard to bacteria, as Salmonella spp. and viable enterococci were not detected in any oyster flesh (edible portion) samples, despite the fact that these bacteria have regularly been found in the farming waters. Furthermore, the level of Escherichia coli contamination was clearly below the legal limit in oysters reared in a class B area (>230-≤4600 MPN E. coli/100 g). On the contrary, norovirus was repeatedly detected in the digestive glands of oysters sampled in autumn, winter, and spring. However, their presence in farming waters was only detected during winter.

Assembling Near-Infrared Dye on the Surface of Near-Infrared Silica-Coated Copper Sulphide Plasmonic Nanoparticles.

Functionalization of colloidal nanoparticles with organic dyes, which absorb photons in complementary spectral ranges, brings a synergistic effect for harvesting additional light energy. Here, we show functionalization of near-infrared (NIR) plasmonic nanoparticles (NPs) of bare and amino-group functionalized mesoporous silica-coated copper sulphide (Cu2-xS@MSS and Cu2-xS@MSS-NH2) with specific tricarbocyanine NIR dye possessing sulfonate end groups. The role of specific surface chemistry in dye assembling on the surface of NPs is demonstrated, depending on the organic polar liquids or water used as a dispersant solvent. It is shown that dye binding to the NP surfaces occurs with different efficiency, but mostly in the monomer form in polar organic solvents. Conversely, the aqueous medium leads to different scenarios according to the NP surface chemistry. Predominant formation of the disordered dye monomers occurs on the bare surface of mesoporous silica shell (MSS), whereas the amino-group functionalized MSS accepts dye predominantly in the form of dimers. It is found that the dye-NP interaction overcomes the dye-dye interaction, leading to disruption of dye J-aggregates in the presence of the NPs. The different organization of the dye molecules on the surface of silica-coated copper sulphide NPs provides tuning of their specific functional properties, such as hot-band absorption and photoluminescence.

Encapsulins: structure, properties, application in biotechnology

In 1994 a new class of prokaryotic compartments was discovered, collectively called “encapsulins” or “nanocompartments”. Encapsulin shell protomer proteins self-assemble to form icosahedral structures of various diameters (24-42 nm). Inside of nanocompartments shells, one or several cargo proteins, diverse in their functions, can be encapsulated. In addition, non-native cargo proteins can be loaded into nanocompartments, and shell surfaces can be modified via various compounds, which makes it possible to create targeted drug delivery systems, labels for optical and MRI imaging, and to use encapsulins as bioreactors. This review describes a number of approaches to the application of encapsulins in various fields of science, including biomedicine and nanobiotechnologies.

Study on wear properties of 7075 aluminum alloy by laser alloying imitating shell surface structure with different unit spacing

Based on observation of shell surface structures of wear-resistant organisms in the nature, Al–Ni "soft-hard interphase" nonsmooth bionic "shell" surface were prepared by adding alloy element Ni into the surface of 7075 Al alloy through laser alloying. Thereby, the wear resistance of 7075 Al alloy materials was significantly improved.By laser alloying and adding alloying element Ni to the surface of 7075 aluminum alloy, the "soft and hard alternating" non smooth bionic surface with different Al Ni unit spacing were prepared. Therefore, the wear resistance of 7075 aluminum alloy material is significantly improved.When the unit spacing was 3 mm, the wear resistance of bionic samples was optimized. In comparison with the untreated samples, the weight loss due to wear declined by 82.14% in the treated samples. Moreover, the stress distribution in the wear process of bionic samples was simulated by ABAQUS finite element simulation software. Together with the microstructure and phase changes of alloyed layers, the wear resistance mechanism of bionic alloyed samples was further analyzed.

Organic Rankine cycle turbogenerator cooling – Optimization of the generator water jacket heat exchange surface

Discharge of excess heat from the micro-turbine electric generator is an important issue for the micro-turbine operation and should be considered during the design process. The manuscript is intended to present a new tool for rapid shape optimization of the heat exchanging surface of the ORC (Organic Rankine Cycle) micro-turbine electric generator. The optimization of the water jacket geometry of a 10 kWe ORC micro-turbine generator is performed by making use of a modified, with respect to the models presented in the literature, 0D heat transfer model of the finned heat exchange surface of the cooling water jacket, and a genetic algorithm. As a result of optimization, an apparent reduction in fin size and increased fin density at the finned wall surface is achieved, yielding a significant increase of the heat transfer coefficient and a temperature decrease of the electric generator stator. The temperature at the shell surface tangential to the electric generator stator was found to decrease by over 6°C. A considerable reduction of temperature gradients around the water jacket wall is also reported.The results of optimization from the 0D model are verified by numerical simulation using a full 3D CFD model of fluid flow and conjugate heat transfer (CHT) in Ansys CFX for the original and optimized geometries. The CFD CHT model was first validated using experiment-based correlations for heat transfer in liquid flow over a circular cylinder pipe for a wide range of Reynolds numbers.The obtained temperature decrease in the optimized ORC electric generator stator for the nominal operating point of the ORC generator is found similar for both 0D and 3D models. The temperatures calculated in the 0D model at the shell surface tangential to the electric generator stator deviate from respective CFD values by 0.5–1.5°C. Another operational case beyond the nominal operating point has been analysed making use of the 3D CFD method as well, showing that the optimized geometry is characterized by an improved heat exchange performance not only for the nominal operating point.

Magnetic Fe3O4@MIL-100(Fe) core-shells decorated with gold nanoparticles for enhanced catalytic reduction of 4-nitrophenol and degradation of azo dye

In this contribution, the metal-organic framework Fe3O4@MIL-100(Fe) have been successfully synthesized via in situ single-step hydrothermal route, where Fe3O4 not only acts as a core but also provide Fe(III) for uniform growth of MIL-100(Fe) shell around Fe3O4 microspheres. Compared with Fe3O4, both surface area and pore volume of Fe3O4@MIL-100(Fe) is significantly enhanced while the magnetism is slightly affected. The synthesis procedure is facile since it eliminates the need of the functionalization of Fe3O4 core with mercaptoacetic acid (MAA), addition of external iron source and repeated cycles of growth and washing. The as-prepared MIL-100(Fe) were decorated with gold nanoparticles (Au NPs) by deposition-reduction method for the first time and applied for fast detection and reduction of 4-Nitrophenol (4-NP) and azo dye to reduce their environmental and health issues. With N2 physisorption, XRD, TEM, SEM, VSM and FT-IR characterization, the metallic Au NPs were identified to be highly dispersed in the Fe3O4@MIL-100(Fe) cages without affecting the magnetism. For Au/Fe3O4@MIL-100(Fe), complete reduction of 4-NP and azo dye occurred within 16 min with reaction rate constant (k) of 0.25 and 0.2 min−1, respectively superior to Fe3O4 core and Fe3O4@MIL-100(Fe), which is attributed to well dispersive Au NPs, texture, and core shell surface of Fe3O4@MIL-100(Fe). Furthermore, the excellent reusability of Au/Fe3O4@MIL-100(Fe) makes it attractive to be used for multiples cycles in catalysis.

Integrated research of corrugation of the inner surface of a cylindrical shell by local plastic deformation

A number of simulations of the corrugation of the inner surface of a cylindrical shell with different depth of notches are carried out, using a working tool lead of a different shape. A study of the stress-strain state and damageability of the material during the local formation of corrugations by a tool of various geometry is carried out. Keywords: corrugation, internal notches, stresses, deformations, damageability, average stresses. yakovlev-ss-science@yandex.ru

Manufacturing of riffle mesh on internal surface of cylindrical shell

A new method for obtaining of responsible purposes products with applied corrugations on the inner surface of a cylindrical shell using the mandrelling method and local plastic change is presented. The technological process and the advantages of the new method are described. Schemes of the process and an example of its implementation are given.

Encapsulins: Structure, Properties, and Biotechnological Applications.

In 1994 a new class of prokaryotic compartments was discovered, collectively called "encapsulins" or "nanocompartments". Encapsulin shell protomer proteins self-assemble to form icosahedral structures of various diameters (24-42 nm). Inside of nanocompartments shells, one or several cargo proteins, diverse in their functions, can be encapsulated. In addition, non-native cargo proteins can be loaded into nanocompartments, and shell surfaces can be modified via various compounds, which makes it possible to create targeted drug delivery systems, labels for optical and MRI imaging, and to use encapsulins as bioreactors. This review describes a number of strategies of encapsulins application in various fields of science, including biomedicine and nanobiotechnologies.

Effect of disinfectants on hatchability and safety of ducklings

High contamination of incubation eggs of waterfowl and, as a consequence, penetration of microorganisms through the shell leads to embryonic mortality, poults weakness, high mortality in the first day of life, so it is important to sanitize eggs immediately after their collection. This article presents the results of using 1.6% hydrogen peroxide solution as a disinfectant for treating incubation duck eggs. The results of microbiological research of washes from the surface of incubation duck eggs, setter air, otoscopy, hatchability and safety of day-old growing are also reflected. During the study, it was found that pre-hatching treatment of duck eggs with 1.6% hydrogen peroxide solution reduced the degree of contamination on the shell surface, hatchability of eggs in the experimental group was higher by 3.1% than in the control group, safety - by 3.6%, respectively.

Investigation of natural vibrations of thin-walled structures interacting with fluid

The problem of studying the dynamics of elements of hydro-technical structures interacting with fluid is considered in the article. On the basis of Lagrange’s variational principles, the basic equations are obtained that characterize the dynamics of complex, multiply connected structurally non-homogeneous shell systems interacting with flowing fluid. Dynamic equations of a cylindrical shell are obtained. To determine the fluid pressure on the shell surface, a boundary value problem based on the laws of hydroelasticity was used. A software package was developed for studying the dynamic characteristics of complex, multiply connected structurally non-homogeneous shell structures, as well as programs for studying the dynamic characteristics of a composite structure using the orthogonal sweep method. Dynamic characteristics are determined for different levels of water filling.