Inner Surface Of Shell Research Articles

Structure and assembly of the α-carboxysome in the marine cyanobacterium Prochlorococcus.

Carboxysomes are bacterial microcompartments that encapsulate the enzymes RuBisCO and carbonic anhydrase in a proteinaceous shell to enhance the efficiency of photosynthetic carbon fixation. The self-assembly principles of the intact carboxysome remain elusive. Here we purified α-carboxysomes from Prochlorococcus and examined their intact structures using single-particle cryo-electron microscopy to solve the basic principles of their shell construction and internal RuBisCO organization. The 4.2 Å icosahedral-like shell structure reveals 24 CsoS1 hexamers on each facet and one CsoS4A pentamer at each vertex. RuBisCOs are organized into three concentric layers within the shell, consisting of 72, 32 and up to 4 RuBisCOs at the outer, middle and inner layers, respectively. We uniquely show how full-length and shorter forms of the scaffolding protein CsoS2 bind to the inner surface of the shell via repetitive motifs in the middle and C-terminal regions. Combined with previous reports, we propose a concomitant 'outside-in' assembly principle of α-carboxysomes: the inner surface of the self-assembled shell is reinforced by the middle and C-terminal motifs of the scaffolding protein, while the free N-terminal motifs cluster to recruit RuBisCO in concentric, three-layered spherical arrangements. These new insights into the coordinated assembly of α-carboxysomes may guide the rational design and repurposing of carboxysome structures for improving plant photosynthetic efficiency.

Bionic dual-scale structured films for efficient passive radiative cooling accompanied by robust durability.

Passive radiative cooling (PRC), as an energy-free cooling approach, is ingeniously harnessed for certain natural organisms to withstand extreme high-temperature climates, which has inspired numerous bionic designs. However, it is a great challenge to enhance the durability of the designed materials in practical scenarios while inheriting the natural biological principles. We demonstrate bionic dual-scale structured (BDSS) films for efficient passive radiative cooling accompanied by robust durability after discovering the excellent thermoregulatory properties of the inner surface of Hawaiian scallop shell. We found that the inner surface of the shell consists of large-scale triangular ridges scattered with small-scale terrace steps. This dual-scale structure can enhance the reflectivity of sunlight by efficient Mie scattering and increase the emissivity in the mid-infrared range by lengthening the propagation of photons, thereby decreasing the surface temperature. Underpinned by this finding, we developed a BDSS film that features a strong solar spectrum reflectivity of 0.95 and a high mid-infrared emissivity of 0.98, achieving a sub-ambient cooling of 10.8 °C under direct sunlight. Additionally, the designed films possess robust durability including excellent self-cleaning, flexibility, mechanical strength, chemical stability, and anti-ultraviolet radiation, which is promising for thermal thermoregulation in various harsh scenarios.

Electron probe microanalysis and gene expression analysis of melanization caused by summer atrophy virus in the Akoya pearl oyster (Pinctada fucata)

The Akoya pearl oyster, Pinctada fucata, is the major species used for pearl culture in Japan. However, a massive mortality of juvenile and mantle atrophy of adult P. fucata have occurred during summer in Japan's major pearl production areas since 2019, and the symptoms were named “summer atrophy,” where a brown substance was deposited on the inner surface of their shell and mainly at the edge of the mantle. Summer atrophy is caused by a non-enveloped virus with a diameter of <100 nm. This study aimed to reveal whether the deposits are melanin and determine the gene expression in the mantle with the deposition through an infectious experiment. The body fluid of diseased P.fucata containing the causative virus was inoculated into the adductor muscle of three-year-old P. fucata. P. fucata were sampled at 0 (before injection), 1, 3, 6, 10, 14, 21, and 35 days post-injection. First, an electron probe microanalyzer was used to observe the detailed structure and material composition of the deposits of experimentally and spontaneously diseased P. fucata. Protuberances and wrinkled structures differed from a normal inner surface shell. Cluster analysis of these elemental composition ratios revealed that the brown deposits formed a cluster with the melanin standard, a prismatic layer of Mytilus galloprovincialis. Therefore, the brown deposits were considered to be melanin. The gene expression of infected mantles was analyzed by quantitative PCR. RNA was extracted from the mantle and body fluids, and the gene expression of shell matrix protein genes (msi31 and msi60), tyrosinase genes involved in melanin formation (OT47 and pfty1), and superoxide dismutase (SOD), which is an indicator of reactive oxygen species, was analyzed. A general linear model was created using the presence of deposits as an objective variable, with virus gene copy numbers in the body fluid and mantle and expression levels of the above five genes as explanatory variables. Then, an optimal model was selected. As a result, OT47, msi60, and SOD were selected as explanatory variables. The results suggest that virus infection induced the up-regulation of SOD and tyrosinase, inducing the deposits on the inner surface of shells in summer atrophy. Melanization is known in many animals and plays a major role in immunity, particularly in invertebrates. In bivalves, melanization caused by bacterial diseases has been reported, but this is the first report of melanization caused by viral diseases.

Semihollow Core-Shell Nanoparticles with Porous SiO2 Shells Encapsulating Elemental Sulfur for Lithium-Sulfur Batteries.

Lithium-sulfur batteries have shown great promise as next-generation high energy density power sources, but their commercial applications are hindered by short battery cycle life arising from the dissolution and shuttling of polysulfides. To address this shortcoming, we prepared two types of semihollow core-shell nanoparticles in which (1) elemental sulfur is encapsulated within a porous silica shell (S@SiO2) and (2) elemental sulfur is encapsulated within a porous silica shell where the inner surface of the shell is decorated with small Au nanoparticles (S@Au@SiO2). These core-shell nanoparticles, both ∼300 nm in diameter, were generated from analogous zinc sulfide-based core-shell nanoparticles (ZnS@SiO2 and ZnS@Au@SiO2, respectively) by converting the ZnS cores to elemental sulfur upon treatment with Fe(NO3)3. With a high surface area and strong host-polysulfide interaction, the SiO2 shells effectively trap the polysulfides; moreover, the internal void space of these nanostructures accommodates the volume expansion of the sulfur core upon lithiation. By decorating ∼5-7 nm Au nanoparticles evenly on the inner surface of the porous SiO2 shells (i.e., S@Au@SiO2), electron transport is enhanced, with consequently enhanced sulfur conversion kinetics at high current rates. Studies of battery performance showed that the S@SiO2 cathode can deliver an initial capacity of 1153 mA h g-1 under 0.2 C and retain 816 mA h g-1 after 100 cycles. More importantly, the Au-decorated S@Au@SiO2 cathode can deliver a high capacity of 500 mA h g-1 under 5 C.

Microscopic evolution of solid-hydrogen shells under the ultrafast dynamic compression

Starting from the same initial structure, solid-hydrogen shells were dynamically compressed at different implosion velocities by performing large-scale molecular dynamic simulations to explore their microscopic evolution under the ultrafast dynamic compression. The ultrafast dynamic compression is revealed to prohibit the solid shell from the structural phase transition, while the phase transition is first initiated at the inner surface of the shell. A faster compression generates a higher pressure in the shell at a given convergence ratio by preventing the hydrogen atoms from ejecting out of the solid-hydrogen shell to release pressure. These results provide a glimpse of the microscopic scenario of the solid-hydrogen shell at early times during the ultrafast dynamic compression, suggesting that the implosion velocity must be carefully determined to mitigate the growth of hydrodynamic instabilities on the inner surface of the solid-hydrogen shell.

Relation between Biofilm and Virulence in Vibrio tapetis: A Transcriptomic Study.

Marine pathogenic bacteria are able to form biofilms on many surfaces, such as mollusc shells, and they can wait for the appropriate opportunity to induce their virulence. Vibrio tapetis can develop such biofilms on the inner surface of shells of the Ruditapes philippinarum clam, leading to the formation of a brown conchiolin deposit in the form of a ring, hence the name of the disease: Brown Ring Disease. The virulence of V. tapetis is presumed to be related to its capacity to form biofilms, but the link has never been clearly established at the physiological or genetic level. In the present study, we used RNA-seq analysis to identify biofilm- and virulence-related genes displaying altered expression in biofilms compared to the planktonic condition. A flow cell system was employed to grow biofilms to obtain both structural and transcriptomic views of the biofilms. We found that 3615 genes were differentially expressed, confirming that biofilm and planktonic lifestyles are very different. As expected, the differentially expressed genes included those involved in biofilm formation, such as motility- and polysaccharide synthesis-related genes. The data show that quorum sensing is probably mediated by the AI-2/LuxO system in V. tapetis biofilms. The expression of genes encoding the Type VI Secretion System and associated exported proteins are strongly induced, suggesting that V. tapetis activates this virulence factor when living in biofilm.

Design of sandwich-walled cylindrical shell structure with initial imperfections

Sandwich-walled cylindrical shell has been built with lattice-like stiffeners by adding another layer of skin in the inner surface of shell. Taking advantage of high mechanical property of lattice-like stiffeners, such as high specific stiffness, high specific strength etc., sandwich-walled cylindrical shell is studied for high load-carrying capacity in this paper. In this study, major parameters of sandwich-walled cylindrical shell is discussed for the effect of load-carrying capacity, and the imperfection sensitivity analysis of sandwich-walled cylindrical shells is carried out based on the eigenmode-shape imperfection approach and the single perturbation load approach. Comparing with the traditional stiffened cylindrical shell, the sandwich-walled cylindrical shell has a higher load-carrying efficiency. The reason of phenomenon is high bending stiffness of lattice-like stiffeners. And then, the optimization design of sandwich-walled cylindrical shells is carried out. It is results that optimum design of sandwich-walled cylindrical shell improved knockdown factor and load-carrying capacity. It can be concluded that sandwich-walled cylindrical shell is a potential structure to be more efficient structure in the future aerospace and aircraft designs.

Влияние формы и размеров носка оправки прошивного стана на образование внутренних дефектов на гильзах и применение непрерывнолитых заготовок для производства труб диаметром менее 121 мм

The research of the influence of the shape and size of the tip of the piercing mill mandrel on the formation of internal defects of the axial fracture area located in the deformation zone of the piercing mill was carried out. Premature axial degradation leads to the formation of defects on the inner surface of shells and pipes. If billets are pierced with higher reduction, it is proposed to use mandrels with the enlarged diameter and tip sphere radius (enlarged tip area). This technical solution was tested in the pipe-rolling unit TPA-140 of “SinTZ” (Kamensk-Uralsky) in the production of an experimental batch of pipes with a diameter of 108 mm from continuously cast billets with a diameter of 156 mm. The study of experimental samples obtained by interrupted rolling showed that using mandrels with the enlarged diameter and the tip sphere radius provides “healing” (sealing) of billet axial fracture. Metallographic studies were conducted to determine the nature of the formed layer of intact (“healthy”) metal in front of the mandrel tip. It was found that this layer was formed by means of back-up forces from the mandrel. The research shows the possibility of using continuously cast billets for the production of pipes with diameters of less than 121 mm.

Development of the CD Symcap platform to study gas-shell mix in implosions at the National Ignition Facility

Surrogate implosions play an important role at the National Ignition Facility (NIF) for isolating aspects of the complex physical processes associated with fully integrated ignition experiments. The newly developed CD Symcap platform has been designed to study gas-shell mix in indirectly driven, pure T2-gas filled CH-shell implosions equipped with 4 μm thick CD layers. This configuration provides a direct nuclear signature of mix as the DT yield (above a characterized D contamination background) is produced by D from the CD layer in the shell, mixing into the T-gas core. The CD layer can be placed at different locations within the CH shell to probe the depth and extent of mix. CD layers placed flush with the gas-shell interface and recessed up to 8 μm have shown that most of the mix occurs at the inner-shell surface. In addition, time-gated x-ray images of the hotspot show large brightly radiating objects traversing through the hotspot around bang-time, which are likely chunks of CH/CD plastic. This platform is a powerful new capability at the NIF for understanding mix, one of the key performance issues for ignition experiments.

Alteration of shell nacre micromorphology in blue mussel Mytilus edulis after exposure to free-ionic silver and silver nanoparticles

This study describes the morphology of inner shell surface (ISS) of the blue mussel Mytilus edulis Linnaeus after short-term exposures to radiolabeled silver in free-ionic ( 110mAg +) and engineered nanoparticulate ( 110mAgNPs, <40 nm) phases. Radiolabeled silver in starting solutions was used in a similar low concentration (∼15 Bq mL −1) for both treatments. After exposure experiments radiolabeled silver was leached from the ISS using HCl. It concentration for shells from both treatments was ∼0.5 Bq mL −1. Whole ISS of young individuals and prismatic layer of adults showed no evidence of any major alteration process after silver uptake. However, the nacre portion of adult mussels exposed to both treatments revealed distinct doughnut shape structures (DSS) formed by calcium carbonate micrograins that covered the surface of aragonite tablets. Scanning electron microscope (SEM) imaging revealed the existence of only minor differences in DSS morphology between mussels exposed to Ag + and AgNPs. From literature survey, DSS were also found in bivalves exposed to Cd 2+. The DSS occurring in a specimen of a field-collected bivalve is also shown. Formation of distinctive DSS can be explained by a disturbance of the shell calcification mechanism. Although the occurrence of DSS is not exclusively associated with metal bioavailability to the mussels, the morphology of DSS seems to be linked to the speciation of the metal used in the uptake experiments.

Autoradiographic study on the distribution of 241Am in the shell of the freshwater zebra mussel Dreissena polymorpha

Autoradiography was used to identify α-track distributions in a series of shell sections from live mussels Dreissena polymorpha Pallas and dissected shells of dead mussels obtained from laboratory experiments using relatively high concentrations of 241Am in the exposure media, a required condition for successful use of this autoradiographic technique. A comparable distribution of α-tracks was recorded on autoradiographs from both live and dead shells suggesting that metabolism does not lead to any sizable changes in the process of 241Am adsorption (present in the extrapallial fluid) onto the inner surface of shell. Autoradiographs showed a preferential accumulation of 241Am in the organic periostracum, whereas the outer and inner shell layers were characterized by a relatively low α-tracks density. No α-tracks were observed in the central part of the shell in any of the samples. These observations will be useful for the development of a general model to explain bioaccumulation and biosorption processes of radionuclides into mollusk shells.

Multimode short-wavelength perturbation growth studies for the National Ignition Facility double-shell ignition target designs

Detailed multimode two-dimensional simulations of short-wavelength perturbations imposed on the material interfaces of a recently proposed indirect-drive double-shell ignition target [Amendt et al., Phys. Plasmas 9, 2221 (2002)] are presented. In this work, the effect of roughness imposed only on the surfaces of the inner shell is studied. Realistic perturbations are adopted from a measured spectrum of a glass capsule (as a surrogate for the high-Z inner shell). It is found that perturbing the inner surface of the inner shell shows minimal degradation in capsule performance. On the other hand, when roughness is imposed on the outer surface of the inner shell, the growth of large Legendre mode number perturbations (l&amp;gt;200) leads to shell breakup. Further analysis reveals a new pathway for the Rayleigh–Taylor (RT) instability. L-shell radiation (&amp;gt;8 keV) from the high-Z hohlraum wall ablates the outer surface of the high-Z inner shell, promoting large outward expansion which is reversed by the converging outer shell. The classic conditions for RT instability are met: low density material pushing onto the higher density inner shell. It is shown that this effect can be controlled by tamping the outward expansion of the inner shell with a variety of materials. Simulations with separate CH and Ti tampers demonstrate that the redesigned capsule can withstand perturbations with high mode number content without exhibiting shell breakup. Furthermore, the outstanding question of determining the cutoff mode number (lc) is addressed by performing simulations with successively larger maximum l, reaching values beyond 1000, and calculating the mix width of the pusher/tamper interface for the CH-tamped case. These numerical studies suggest that the mix width approaches a constant value close to 40% of the shell width at peak compression. While not a proof that lc has been found, this result suggests that a mix-relevant mode number may be within reach of current simulation capabilities.

Theory of laser-induced adiabat shaping in inertial fusion implosions: The decaying shock

The evolution of a decaying shock driven by a laser prepulse in inertial confinement fusion (ICF) capsules is investigated including the effects of mass ablation and residual ablation pressure. The adiabat (entropy) profile left behind by a decaying shock is calculated and compared with the results of one-dimensional simulations. It is found that the adiabat shape follows a simple power law of the areal density α=αinn(mshell/m)δa, where αinn is the shell inner surface adiabat, mshell is the initial total shell areal density, and m is the local shell areal density. The power law index δa varies from 1.12 for prepulses in the 100 ps range to 1.20 for prepulses in the 300 ps range. This adiabat profile accurately reproduces the simulation results to within a few percent. A simple procedure aimed at designing a laser pulse inducing the maximum adiabat ratio between the outer- and inner-shell surface is also developed. ICF capsules with a shaped adiabat are expected to benefit from improved hydrodynamic stability while maintaining the same one-dimensional performance as flat adiabat shells.

Deceleration phase of inertial confinement fusion implosions

A model for the deceleration phase and marginal ignition of imploding capsules is derived by solving a set of ordinary differential equations describing the hot-spot energy balance and the shell dynamics including the return shock propagation. It is found that heat flux leaving the hot spot goes back in the form of internal energy and PdV work of the material ablated off the inner-shell surface. Though the hot-spot temperature is reduced by the heat conduction losses, the hot-spot density increases due to the ablated material in such a way that the hot-spot pressure is approximately independent of heat conduction. For hot-spot temperatures exceeding approximately 7 keV, the ignition conditions are not affected by heat conduction losses that are recycled into the hot spot by ablation. Instead, the only significant internal energy loss is due to the hot-spot expansion tamped by the surrounding shell. The change of adiabat induced by the shock is also calculated for marginally igniting shells, and the relation between the in-flight and stagnation adiabats is in general agreement with the numerical fit of LASNEX simulations by Herrmann et al. [Nucl. Fusion 41, 99 (2001)] and the self-similar solution of Kemp et al. [Phys. Rev. Lett. 15, 3336 (2001)]. The minimum kinetic energy required for ignition is also calculated from the same model and shown to be in good agreement with the numerical fit of LASNEX simulations. It is also found that mass ablation leads to a significant reduction of the deceleration phase Rayleigh–Taylor instability growth rates and to the suppression of short wavelength modes.

Study of a converging short pressure pulse generated in a cylindrical polymer shell by an electron beam

This paper presents experimental and theoretical results from an investigation of the excitation and propagation of converging pressure waves in cylindrical shells made of polymethyl methacrylate (PMMA) producing spalling phenomena in the inner surface of the shell. It is found that fracture of the inner surface of a cylindrical shell requires a greater load as compared to the fracture of the rear side of a planar plate of the same material. The reasons for the observed phenomena are analyzed. The experimental results are compared with the results of a numerical simulation that takes into account phenomena occurring in the nonlinear region of elastoplastic deformation of polymer materials used as a base and in composite materials.

A New Approach to Stress Analysis of Various Wound Vessels

As the width of windings of wound pressure vessels increases, the vessels are categorized as filament-wound, ribbon-wound, thin plate-wound, and finally the conventional multilayered vessels. The filament-wound vessel is one of the wound vessels with small winding width. A multilayered vessel can be regarded as one where the winding width is very great. Based on winding width, the other types of wound vessels are structurally situated between the filament-wound vessel and the multilayered vessel. As the winding width increases, the stress state in the windings gradually changes from purely biaxial to triaxial, and the windings are able to carry more axial load. Therefore, the windings and the inner shell of any wound vessel should mechanically behave in a state between that of the filament-wound and nonwound multilayered vessels, depending on winding width. By utilizing an analysis technique, analogous to mathematical interpolation, a new approach for calculating stresses for various wound vessels has been developed. The technique uses the stresses in the filament-wound vessel and of the multilayered vessel with the same dimensions, and compensates for the winding width through the use of a weighting factor. Comparisons between theoretical analyses and experiments are given for flat steel ribbon-wound vessels. The results show that the calculated stresses at the inside surface of inner shell are in very good agreement with published experimental data.

On the So‐called Mantle Muscle Scars on Shells of the Margaritiferidae (Mollusca, Pelecypoda), with Observations on Mantle‐Shell Attachment in the Unionoida and Trigonioida

Mantle attachment scars on the inner surface of shells of the Margaritiferidae have been traditionally regarded as sites of mantle muscle attachment; however, the actual occurrence of muscle tissue at points of attachment has never been verified. Mantle attachment scars occur on shells of seven examined species of margaritiferids. Gross and histological investigation of the mantle of five species reveals that mantle attachment involves modification of mantle epithelial cells and associated connective fibers within the mantle. The connective fibers within the mantle do not appear to have contractile properties, but along with the attachment cells probably provide support for the mantle. Mantle‐shell attachment scars similar to those of margaritiferids also occur in shells of recent trigonids, thus strengthening arguments for a phylogentic link between the Unionoida and Trigonioida.

Deformations of the inner shell surface ofVenerupis pullastra(Montagu) (Lamellibranghia) as a result of infection by a trematod metacercaria with a note of Parasitism Leading to Parasitic Castration

Abstract Brown patches and erosion pits were found on the inner surface of shells of Venerupis pullastra. The deformations were apparently caused by metacercariae of the trematode genus Gymnophallus. The brown calcified material seemed to be the result of unsuccessful attempts by the host to encapsulate the parasites, using calcium taken from the shell. The shells were classified into four categories according to the degree of deformation. 45.5% of the shells were deformed. Infection was found to commence when the shells were between one and two years old. 15% of the three year old shells were affected. Infection increased rapidly after the third year and reached 75% by the ninth year. Only the older specimens showed severe deformations. Infection did not affect growth of the host's shell. Two females out of 516 individuals showed probable parasitic castration caused by another type of cercariae.

アコヤガイの物質代謝に関する研究-III

Among various kinds of tissue, the rate of respiration was the highest in the gills and very low in such tissues as the adductor muscle and outer epithelium adhering to the inner surface of shell (Table 1). The amount of oxygen consumption of the gills, measured at 25°C., was higher in winter than in summer (Table 2). The respiration of excised gill piece was blocked by cyanide, azide, αα'-dipyridil, salicylaldoxime and iodoacetate, and stimulated by methylene blue and 2, 4-dinitrophenol (Table 3, Fig. 1 & 2). The inhibition by salicylaldoxime seems to suggest that a copper enzyme might play an important role in the respiratory system of the gills as well as an iron enzyme, cytochrome oxidase, which has been previously proven by the writer.