Conglomerate Structure Research Articles

STRUCTURE, OPTICAL PROPERTIES AND PHOTOCATALYTIC ACTIVIYY OF UNDOPED, La2O3-DOPED ZnO NANOCOMPOSITES

La-doped ZnO nanocomposites with di­ffe­rent content of La2O3 (1–5%) were obtained by the Pechini method from their nitrate solutions. The solutions of Zn2+ and La3+ nitrates were preliminary obtained by dissolving of zinc and lanthanum oxides with a content of the main component of 99.99% in nitric acid. The influence of lanthanum doping the on the microstructure, morphology, optical pro­perties and photocatalytic activity of the ZnO nanopowders were examined. The properties of the nanopowders were studied by using X-ray phase analysis, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy. The samples were subjected to X-ray powder diffraction using a DRON-3 diffractometer (Cu-K radiation) at room temperature. The scan angle was 0.05–0.1 ° in the range 2 = 15–90 °. X-ray phase ana­lysis confirms the formation of single phase of La2O3-doped ZnO powders on diffractograms. Raman light scattering and photoluminescence spectra were recorded using a Horiba Jobin‑Yvon T64000 spectrometer equipped with a CCD detector at room temperature in the inverse scattering geometry. According to SEM results, the powders characterized a conglomerate structure. The undoped ZnO has an average particle size of 43 nm, while the average particle size of La3+-doped ZnO ranges from 64 to 80 nm. It was established that the morphology of powder particles primarily depends on the content of La3+ in the material. An increase in the amount of La3+ in zinc oxide leads to an increase in the specific surface area (from 3.8 to 11.8 m2/g). In the photoluminescence spectra of ZnO powders, with increasing La2O3 concentration, bands at 400 nm are observed due to the appearance of impurities that cause of interstitial zinc and zinc vacancy defects and their broade­ning with a shift to the long-wave region. Photocatalytic properties of ZnO pow­ders doped with lanthanum oxide were in­vestigated using Methyl Orange as a model dye under Osram Ultra-Vitalux lamp (300 W) irradiation. A present result indicates that the obtained powders are potential candidate for the practical application in photocatalysis.

Dual‐board governance and board independence: Conglomerate affiliate versus standalone firms

AbstractWe argue that the corporate board of an exchange‐listed firm cannot make an independent business decision if it has an affiliation with a conglomerate group. This is because the corporate board of a conglomerate‐affiliated firm (CAF) has high moral hazard exposure due to its accountability to the superior parent board at the apex of the conglomerate structure. Based on a sample of 304 listed firms from 18 countries, we find a CAF board is less independent than a standalone board with no superior reporting body. A firm's affiliation with the conglomerate per se affects its board independence, regardless of the parent shareholding level. The additional analysis finds that the lack of board independence significantly impacts a CAF's financial performance, although the market impact is insignificant.

Quantifying the Microdistribution of Different Fluid Types in the Multiscale Pore Throat Structure of Low-Permeability Conglomerates

The volumes of different fluid types and the pore throat structure in low-permeability reservoirs are crucial parameters for understanding flow mechanisms and predicting production performance. The previously applied methods for distinguishing different fluid types are mainly based on T2 spectra under saturated, centrifugal, and heat-treated conditions. However, for rocks with different mineral compositions and pore structures, the critical temperature between capillary-bound fluid (CAF) and clay-bound fluid (CLF) differs from 60 to 100 °C. Moreover, the alteration of temperature can cause the transformation of clay minerals and a change in a nanopore structure. Herein, an improved method that integrates nuclear magnetic resonance (NMR) tests (n-dodecane-saturated, centrifugal, and spontaneous imbibition treatment conditions) and multicycle mercury intrusion porosimetry, was proposed for quantitatively evaluating the microdistributions of different fluid types, classifying the pore throat system, and analyzing the relationship between pore throat structure and different fluid types in low-permeability conglomerates. Based on the fractal characteristics and mercury intrusion/extrusion characteristics of pore throats at different scales, the pore throat system in these conglomerates was divided into macropore throats (>1 μm), mesopore throats (0.2–1 μm), and micropore throats (<0.2 μm). Macropore throats are connected to intergranular pores (>100 ms); mesopore throats are mostly connected to intergranular pores and intragranular dissolved pores (>10 ms); and micropore throats are connected to intragranular dissolved pores (<10 ms) and clay-related pores (<3 ms). The proportions of movable fluid, CAF, and CLF in the low-permeability conglomerates are 20.4–57.4%, 6.67–32.2%, and 36.0–47.4%, respectively. The movable fluids are mainly distributed in macropore throats and mesopore throats. CAF mainly exists in the micropore throats (pore throat radius <0.2 μm and pore size <10 ms). CLF is mainly distributed in pores with T2 < 3 ms, that is clay-related pores. The improved method of fluid typing is suitable for low-permeability or tight clastic reservoirs (excluding shale).

Pattern Formation in Two-Component Monolayers of Particles with Competing Interactions.

Competing interactions between charged inclusions in membranes of living organisms or charged nanoparticles in near-critical mixtures can lead to self-assembly into various patterns. Motivated by these systems, we developed a simple triangular lattice model for binary mixtures of oppositely charged particles with additional short-range attraction or repulsion between like or different particles, respectively. We determined the ground state for the system in contact with a reservoir of the particles for the whole chemical potentials plane, and the structure of self-assembled conglomerates for fixed numbers of particles. Stability of the low-temperature ordered patterns was verified by Monte Carlo simulations. In addition, we performed molecular dynamics simulations for a continuous model with interactions having similar features, but a larger range and lower strength than in the lattice model. Interactions with and without symmetry between different components were assumed. We investigated both the conglomerate formed in the center of a thin slit with repulsive walls, and the structure of a monolayer adsorbed at an attractive substrate. Both models give the same patterns for large chemical potentials or densities. For low densities, more patterns occur in the lattice model. Different phases coexist with dilute gas on the lattice and in the continuum, leading to different patterns in self-assembled conglomerates ('rafts').

Design and application of a novel 3D printing method for bio-inspired artificial reefs

Morphological complexity and diversity are key design features for forming artificial reefs that can support marine communities. Towards this end, 3D Printing (3DP) has become a unique fabrication method in the field. In the current study, we develop a novel approach to ceramic 3DP and investigate new morphologies to form marine habitats using additive manufacturing (AM) with eco-friendly materials. A large Paste Based Extrusion (PBE) 3D printer was used in addition to adapted, ceramic materials to develop a Gravity-Stimulated Printing Design method (GSPD) to fabricate bio-inspired reef designs. This approach used a direct parametric design-tool that generates and controls a specific machine tool-path of the printer, bypassing the slicer program. The developed parametric design-tool led to highly complex shapes that assembled a spatial conglomerate structure with the variety and uniqueness of each part. A reef forming prototype made from 87 printed parts was created and installed in a coral reef environment at the northern tip of the Red Sea in the Gulf of Eilat/Aqaba. After two years, we observed abundant marine organisms settling and recruiting at a depth of 12 m to form a new reef. This study demonstrates the environmental potential of AM, specifically in ceramic 3D printing. Our results indicate that the GSPD method can be used for large-scale production of highly complex eco-friendly artificial marine habitats. Using our design approach, we can facilitate morphological complexity in ceramic AR construction that support a diversity of coral reef residents.

The increasing number of subsidiaries and stock price crash risk: evidence from the Chinese stock market

PurposeWith the development of the economy, an increasing number of listed companies form subsidiaries in China. Though the increase in the number of subsidiaries affects the hierarchical structure and risk of conglomerates, few studies relate the hierarchical relationship between the parent company and its subsidiaries to its capital market performance at the conglomerate level. Therefore, this study aims to investigate the relationship between the number of subsidiaries and crash risk.Design/methodology/approachUsing a sample of all the A-share companies in the Shanghai and Shenzhen stock markets from 2007 to 2015, this study conducts multivariate regression analyses between the number of subsidiaries and the stock price crash risk.FindingsThis study finds an inversed U relationship between the number of subsidiaries and the stock price crash risk, and the above inversed U relationship is steeper in conglomerates with stronger managerial power and less finance distress.Originality/valueThis research has an incremental contribution to the agency problem and governance effect of the parent–subsidiary system in conglomerates. To the best of the authors’ knowledge, this is the first study to show a significant quadratic relationship between the future crash risk and the number of subsidiaries. This paper provides new evidence that the number of subsidiaries has an incremental ability to predict future firm-specific crash risk above other predictors identified by previous research.

EFFECT OFTHE COMPACTION PROCESS ON THE CONGLOMERATE STRUCTURE AT PRODUCTION OF CONSTRUCTION MATERIALS

Formulation of the problem. The process of densification of mixtures of construction products that are being formed or molded is an important stage in the formation of a macrostructure, since during this period, granular and other components of the composite that fill it are relatively firmly fixed in a viscous medium. A large number of publications are devoted to the study of this issue, but many aspects of the effect of compaction on the structure of a conglomerate are not yet known, and the results obtained have not been systematized. Introduction. Preliminary compaction of the mixture reduces the fragmentation of particles, transferring bonds from point to interfacial along the contact boundaries. With the approach of particles to very small distances, repulsive forces arise and increase. Ultimately, the resultant force acts, which, at a certain optimal distance of particles from one another, provides the initial cohesion of the raw product. Fixation occurs both directly by adjoining the components, including with the possibility of intergrowth (for example, crystals), and through interlayers of a completely hardened or gradually hardening binder. In conglomerate materials, contact through interlayers at the compaction stage is more typical than direct contact or coalescence of particles under the influence of surface energy, chemical bonds, or other, including complex, factors. Objective. The aim of the work was to establish the features in the formation of the structure of the conglomerate from the preliminary compaction of the mixture, as well as its influence on the functional and technological characteristics. Methods. Solving the problem of the optimal structure of a conglomerate requires identifying the relationship between the type, concentration, composition of raw materials, the method of compaction and the resulting functional characteristics of the product. Results. Optimization of the structure while maintaining the level of desired properties corresponds to achieving the highest quality in a material or product. Technology by this criterion becomes progressive. To reduce the water penetration of cement concretes, it is necessary to provide optimal conditions for cement hydration and the creation of a dense conglomerate with a minimum number of pores. In connection with the relevance of creating building materials and products from materials of the construction environment (soil blocks) and reducing energy consumption during molding and pressing, it is necessary to continue the development of technologies and equipment designs to obtain the optimal conglomerate structure with minimal water penetration. Conclusion. Studies of the effect of compaction of raw materials on the structure of conglomerates are ongoing, but already these results indicate that the rate and form of conglomerate formation change significantly at optimal values of pre-compacted raw materials.

SiO2/Al2O3/C grafted 3-n propylpyridinium silsesquioxane chloride-based non-enzymatic electrochemical sensor for determination of carcinogenic nitrite in food products

The excessive uptake of nitrite is perilous and detrimental for human health that prone to cancer disease. Herein, described the synthesis of SiO2/Al2O3/C material through the sol–gel procedure followed by grafting with 3-n propylpyridinium silsesquioxane chloride organic ligand for enhancing electrochemical activity. H-NMR, 13C NMR, and 29Si studies were performed for confirmation of surface functionalization through the grafting technique. The surface morphology was evaluated through SEM and TEM techniques. The material showed an irregular and flakes-like structure that exhibited more compactness and conglomerate structure with no segregation in phase was observed after grafting. The elemental composition was confirmed from EDX analysis. The electrochemical measurements were performed with cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and chronoamperometry. The prepared hybrid inorganic–organic composite Si/C/Al/SiPy+Cl- was applied for the modification of the glassy carbon (GC) electrode and assessed as a sensor for nitrite determination. The sensor showed the low limit of detection (0.01 μM), low limit of quantification (0.08 μM), wide linear response range (0.2–280 μM), and high sensitivity (410 μA·μM−1). It gave a quick response time of <1 s in the presence of 70 μM nitrite. The fabricated sensor showed high sensitivity, chemical stability, and insignificant interference from co-existing species present in sausage meat and food industry discharges. The repeatability of the sensor was evaluated as 2.5 % R.S.D.; for n = 10 at 50 μM nitrite.

Investigation of the structure of cement conglomerates

This article describes the structural studies of a cement conglomerate, its evolution from the moment of formation to the loss of operational properties. Physical and chemical phenomena and interactions of various elements of cement stone are considered. The study of its rheology includes creating a virtual model and monitoring the formation of the structure of cement pastes by acoustic emission (AE). The results of combined experimental studies to determine the residual life of cement stone samples using AE and tensometry methods are presented. The authors created a complex for monitoring the stress-strain state of artificial conglomerates, which includes both internal and acoustic sensors.

О причинах разрушения железобетонных изделий и конструкций для энергетического строительства

The problems of operating concrete and reinforced concrete products are connected with the specifics of this structural material. The multi-scale structure of this material is a strict hierarchical multi-level system, which reflects the state, properties and defects of each level. This determines the deformation range of the entire conglomerate capillary-porous structure. Operational factors in the destruction of reinforced concrete constructions include: static load from suspensiondevices, wires and other equipment; dynamic effects from wind and rolling stock; ambient temperature and humidity; aggressive effects of soil and atmosphere; electro corrosion caused by leakage currents. This paper considers factors that are capable of causing defects thus leading to the destruction and loss of operational characteristics of reinforced concrete products and power plant constructions. In order to reveal the nature of premature destruction, literature data on structures, which are most frequently subject to destruction, were analysed.

Carbonate sludge as a nanostructured material for environmental engineering

The behaviour features of carbonate sludge which are a waste of water treatment process were studied in aqueous and oil environment. Based on the analysis of images of carbonate sludge particles in liquid media made by laser scanning confocal microscopes, the existence of nanostructures of various chemical compositions having several hundred nanometers in size, both single and forming porous conglomerate structures with a developed surface was revealed. The existence of such fragmentation of fine carbonate sludge powder particles in liquid media suggests that the mechanism of action of sludge additives is similar to that of nanoparticles. It was shown that the waste of the water treatment can be used as a cheap and environmentally friendly nanostructured material for industrial and environmental engineering, in particular, to improve the properties of hydrocarbon fuels. If necessary, the effect of carbonate sludge can be enhanced by changing its composition at the coagulation stage or by adding other nanoparticles. The data on the composition and texture characteristics of used sludge were given.

Rheometric flows of concentrated suspensions of solid particles

Publications on experimental and theoretical studies of the rheological properties of concentrated suspensions of solid particles have been analyzed. According to the currently accepted ideas, the rheology of suspensions is considered as a result of contact interaction of their constituent particles caused by the action of external forces, the formation and destruction of various types of conglomerate structures. A new rheological model of a highly concentrated suspension of solid particles in a Newtonian fluid is proposed, which describes both a continuous and discontinuous increase in the effective viscosity with a uniform increase in shear stresses. Accurate analytical formulas are obtained for the velocity profiles of suspensions in rotational viscometers “cone-plane” and “cylinder-cylinder”, as well as in a slit viscometer. The proposed model is modified to take into account the non-Newtonian properties of a dispersion medium, which exhibits pseudoplastic properties at low strain rates, and dilatant properties at large strain rates. The effective viscosity of such a suspension is presented as the sum of the contributions from the dispersion medium and the solid particles of the dispersed phase. To describe the rheology of the dispersion phase, the Ellis model was used. The velocity profiles in a pressure driven flat channel are obtained numerically by the finite element method. It is shown that, depending on the parameters of the model, the velocity profiles in a flat channel can take various complex forms.

In situ self-assembly of molybdenum disulfide/Mg–Al layered double hydroxide composite for enhanced photocatalytic activity

In this work, in situ growth of thin layer and highly catalytic activity molybdenum disulfide (MoS2) was successfully synthesized by spatial confinement effect of Mg–Al layered double hydroxide (Simplified as LDH below). Due to the unique spatial confinement effect and electropositivity of the LDH layer, MoS2 will controllable in situ grows along the surface of LDH layer, the MoS2 synthesized in LDH tends to monolayer or thin layer instead of growing into a flower-like structure, this new strategy is different from vapor deposition, exfoliation and laser irradiation to prepare thin layer MoS2. Meanwhile, the conglomerate structure of LDH is opened and converted to thin layer by the growth of MoS2, too. The rich defects carried by thin layer LDH also help to improve the catalytic ability of MoS2. MoS2/LDH can absorb the light from ultraviolet to visible light region, The prepared MoS2/LDH composite was used as a photocatalytic material, and was found to be the best photocatalyst degrading about 96% of the MB solution (20 mg/L) after 180 min.

Effect of Bank Holding Company Structure on Farmers’ Financial Welfare in Nigeria

This study examines the impact of bank holding structure on the financial welfare of farmers. We used an expost facto research design and studied all the 18 deposit money banks in Nigeria. We used dummy variable to measure bank conglomerate structure for the period between 2001 and 2018. We also identified the features of financial holding companies based on firms’ specific variables including portfolio condition, competitive standing, equity characteristics and sizes. Based on our analysis, bank holding structures significantly and positively affect banks’ propensity to create risk assets to farmers (coefficient=0.34; p-value less 5%). This implies that ring fencing banks leads to increase in credit availability to farmers and consequently their welfare advancement in Nigeria. Banks with holding structure have competitive advantage and this competiveness benefits farmers significantly (coefficient=0.05; p-value &lt; 0.05). Our analysis also shows that banks with holding structures diversify into non-interest source of revenue, which yields positive and significant effect on farmers’ financial welfare (coefficient= 2.05). Thus, diversifying conglomerating banks can outperform their peers in terms of risk asset making for farmers to extent that relative to non conglomerate banks, up to 2.05% of credit is allocated to farmers for every unit change in bank market due to holding structures. Variation in deposit demands, and gross assets were found to advance loans to farmers. However, default risks and liquidity risk of conglomerate banks limits their credit availability to farmers, which implies that conglomerate banks are highly sensitive to liquidity and default risks. We also found that conglomerate banks allocates risks asset to farmers based on the national economic growth level. Thus, as the economy improves conglomerate banks’ desire to make risk assets to farmers also increases. We recommend that regulators should improve economic growth in order to draw banks into lending to farmers. Conglomerate banks should be protected from default shocks and liquidity risks in order to encourage them to lend more to farmers.

France

France is home to numerous banks and insurers which are very active at a global scale. Four Global Systemically Important Banks (G-SIBs) are incorporated in France as well as multiple number of large insurers. Assets of banking system exceed GDP by 2.7 times. Four G-SIBs dominate France’s financial landscape, also taking into account bancassurance (i.e., banking and insurance companies working under financial conglomerate structure) business model they have. Global presence and diversification, integration of banking and insurance activities defined the perimeter and scope of systemic risk assessment (including stress testing) of FSAP. This technical note contributes to the FSAP’s assessment of systemic risk with a comprehensive set of stress testing exercises. The assessment is based on stress tests, which simulate the health of banks, insurers under severe yet plausible (counterfactual) adverse scenarios. Scenarios include global and regional financial market turmoil (shocks to term and risk premiums), a major slowdown of economic activity in Euro Area (EA) and France due to secular stagnation and trade shocks. The analyses include simulations based on solvency and liquidity scenarios.

Роль региональных холдингов в развитии инновационных процессов: кузбасская специфика

Innovative activity in the form of innovative projects aimed at upgrading production potential is a cornerstone for technological advancement of the largest integrated enterprises – regional versatile holdings – which have played a key role in economic development of the Kemerovo region over the last decade. Regional holdings, being conglomerate structures, form innovative processes in various industries of production, and produce various needs for the sphere of innovatics, with some of them being satisfied by other market participants. It forms close interactions in the innovative sphere and leads to the inevitable perception of the methods applied in innovation management accepted at large holdings by all participants of innovative processes, in particular, in case they carry out a part (stage) of process or a major innovative project for a holding as a customer. The degree and forms of impact of innovative activities of holdings on the innovatics of other participants as well as the directions of their interaction seem various; however, participation of large and authoritative holding structures in such projects has become a peculiar trigger giving boost to a new quality of innovative activity at the enterprises. The synergy effect resulting from such an interaction is sure to make a positive impact on innovative development of Kuzbass regional economy.

Revealing the Role of Structural Features in Bulk Mechanical Performance of Ternary Molecular Solids of Isoniazid.

Mechanical performance in ternary (3n) molecular solids has been rarely studied, and hence it is an interesting topic of investigation in the direct compression method of tableting. The structural features of 3n-eutectic (3n-Eu: INZ-ADP-NIC) and 3n-cocrystal (3n-Co: INZ:SUC:NIC) were explored to understand the bonding area-bonding strength (BA-BS) interplay. Higher compressibility and lower values of the Heckel parameter of 3n-Co as compared to 3n-Eu suggested its better deformation behavior, with BA being the predominant factor. The higher tensile strength and Walker analysis indicated a higher compressibility coefficient ( W) and lower pressing modulus ( L) for 3n-Eu, which was consistent with its better tabletability over 3n-Co. The higher compressibility and plastic energy, and higher value of L of 3n-Co, were attributed to the facile propagation (⟨-1' 0' 5'⟩) of the shearing molecular slip (-1 0 5) when subjected to the external mechanical stress. Thus, the overall higher tableting performance of 3n-Eu over 3n-Co was found due to the predominant BS and limited contribution of BA. The latter was the dominant factor in 3n-Co. Cohesive interactions, like the 3D mechanically interlocked structure of conglomerates of 3n-Eu, contributed toward the higher BS. Moreover, the prediction of better tabletability solely based on crystallographic feature slip planes (0D/1D/2D H-bonded layer (h k l) ⊥ vdW interactions) is warranted in pharmaceutical molecular solids. Eutectics with varying microstructural variants ( nLα + nLβ + nLγ) may open up the opportunity to manipulate the physicomechanical performance.

Rock fabric and pore structure of the Shahejie sandy conglomerates from the Dongying depression in the Bohai Bay Basin, East China

The pore structure of sandy conglomerates, which is primarily controlled by the rock fabric, is a key topic in the microscopic physical study of reservoirs and is also of great significance for sandy conglomerate reservoir evaluation. This study focuses on the rock fabric and pore structure characteristics of sandy conglomerates of the upper submember of the fourth member of the Eocene Shahejie Formation (Es4U) in the Dongying depression, Bohai Bay Basin, East China. This study incorporates integrated approaches of casting thin-sections, scanning electron microscopy (SEM), X-ray diffraction, high-resolution core scanning image acquisition, grain size analysis, physical property tests and mercury injection. The sandy conglomerates mainly consist of pebbly sandstone and gravel sandstone; feldspar and rock fragments are dominant rock components, followed by quartz, with ranging from 25.8% to 37.7% (averaged 31.8%), 21.8% to 46.9% (averaged 31.1%) and 17.0% to 34.4% (averaged 28.0%), respectively. The pore types mainly include primary pores, secondary interparticle (interP) pores and secondary intraparticle (intraP) pores, in addition to some microcracks and intercrystalline pores. Rock textures are divided into two types according to sorting features and roundness: uniform and uneven. Porosity values are between 2.2% and 16.5% and exhibit positive correlations with quartz content and grain size and negative correlations with the content of rock fragments, interstitial material, gravel distribution uniformity, sorting coefficient and maximum particle size. In contrast, the relationships between displacement pressure and these rock fabric parameters show very different trends. The different relationships suggest that rock fabric is closely related to pore structure. In particular, sandy conglomerate samples have a relatively high compositional maturity and uniform rock texture and exhibit a better pore structure. Four typical samples were chosen to verify the relationship between rock fabric and pore structure in the logging profile of Well YN22-22. The results strongly suggest that the rock fabric can be used to indicate the effectiveness of the reservoir in the study area.

Observation of Nucleation and Growth Mechanism of Bismuth Nano/Microparticles Prepared by Hot-Injection Method

The growth mechanisms of the nanomaterials such as Bismuth (Bi) are investigated since the understanding of the factors that affect the kinetics is fundamental to tune the crystal growth and thus to achieve new types of nanostructures and new material properties. It is concluded that Bi nano/microparticles are grown in following: classical nucleation growth theory and then most possibly unclassical oriented attachment via two kinds of effective and noneffective collisions with mass transfer. Polycrystalline Bi nano/micropowders having variety forms such as nanocrystal, nanoplate, and nano/microparticle have been synthesized successfully in a non-coordinating solvent by using hot-injection method. The X-ray powder diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), Fourier transform infrared (FTIR) spectroscopy, and energy dispersive X-ray (EDX) techniques are used to characterize the nanopowders. It is achieved that Bi particles synthesized during the reaction are accumulated via hit and stick mechanism and taken out of the solution as a conglomerate wet powder without need to centrifuge the solution. The Bi is formed in hexagonal phase with preferred orientation of (012) plane along with the XRD peak shape factor of ~0.44 which indicates more Lorentzian than Gaussian character. The average diameter of the synthesized nanocrystals is about 1.86 nm. The unit cell parameters calculated by Rietveld refinement are a=4.5474 Å and c=11.8612 Å in hexagonal phase. It is observed that hexagonal nanoplates are completely surrounded by nanocrystals. Twinkling of the spherical Bi nano/microparticles attached by nanoplates is observed under a white light illumination. All the steps from nucleation to the conglomerate structure formed are visualized and respectively proved experimentally.

Three-dimensional numerical reconstruction method for irregular structures of granular geomaterials

Granular geomaterials are comprised of many geometrically irregular and randomly distributed particles on multi-scales that strongly affect their physical and or mechanical properties. However, providing an accurate representation or characterization of the complex structures of granular geomaterials remains a challenge. In this study, we propose a novel computerized method to numerically represent a three-dimensional (3D) irregular granular structure based on a natural conglomerate sample. To represent the 3D granular structure, the reconstruction algorithm incorporates a two-point probability function along both the principal and diagonal directions, as well as a linear-path function along the principal directions of the model, and a multithread parallel computing algorithm is used to accelerate the 3D reconstruction process of the irregular structures. To validate the accuracy of the proposed algorithm, the characteristics and mechanical properties of the reconstructed 3D granular structure are analyzed and compared with those of the prototype conglomerate sample. This comparison shows that the proposed algorithm improves the reconstruction efficiency of previous algorithms, and the reconstruction model exhibits greater similarity to the natural conglomerate structure than previous reconstruction models. This proposed computational method can also be used to reconstruct other granular structures.