Shell Charge Research Articles

CLAY-STARCH NANOCOMPOSITE COATINGS ON PAPER SUBSTRATE - A PROMISING FRONTIER IN ENVIRONMENTALLY FRIENDLY PACKAGING MATERIAL

The growing concern for environmental sustainability has created an urgent need for the development of innovative and environmentally friendly packaging materials. Among the various options available, clay-starch nanocomposites have emerged as a promising avenue for improving the barrier properties and mechanical strength of paper substrates. In this scientific paper the importance of clay-starch nanocomposite coatings on paper substrate and highlight the role of computer simulations, especially molecular dynamics, in elucidating their structural and functional properties. It has been shown that phyllosilicates with a layer charge < 0.4 electrons per stoichiometric unit can intercalate starch in the interlayer space, forming a barrier for water vapor in the covering layer. Phyllosilicates with a shell charge of >0.4 electrons per stoichiometric unit were not able to intercalate starch. Thus, clay-starchnanocomposites can provide limited water vapor transfer rates and can be recommended asa promising material for dry food packaging.

Quasinormal modes and echo effect of a cylindrical anti–de Sitter black hole spacetime with a thin shell

This paper investigates the quasinormal mode (QNM) vibrations of a rotating cylindrical black hole (or black string) spacetime that is surrounded by a thin shell rotating synchronously with the black string's axis. The existence of the thin shell leads to a piecewise metric of the black hole spacetime beyond the horizon, which is divided into two stationary spacetime parts by the radius of the thin shell. As a result, the potential function $V(r)$ of the QNM equation is also discontinuous. To solve the QNM equation with the discontinuous potential function, we propose two methods, the matrix method and the generalized Horowitz-Hubeny method. We find that the influence of the thin shell can reduce the QNM frequency of the black string while alleviating their amplitude decay rate. Our suggested method can be easily applied to other QNM calculations of black hole spacetime with discontinuous potential function, thus facilitating investigations into more intricate and realistic black hole spacetimes, such as those with accretion disks. Additionally, the finite difference method is employed to investigate the spacetime too. This analysis discloses a substantial gap in the potential function when the thin shell's mass and charge achieve sufficiently high values, resulting in the outer spacetime nearing gravitational collapse and extreme black hole scenarios. Within this gap, the QNM wave displays oscillations, producing an echo effect. Moreover, it is established that the closeness of the spacetime to the collapse threshold and charge extremality have positive correlation with the beat interval of this echo.

An Electron Model Based on the Fine Structure Constant

In previous publications, the author has proposed a model of the electron’s internal structure, wherein a positively-charged negative mass outer shell and a negatively-charged positive mass central core are proposed to resolve the electron’s charge and mass inconsistencies. That model is modified in this document by assuming the electron’s radius is exactly equal to the classical electron radius. The attributes of the internal components of the electron’s structure have been recalculated accordingly. The shape of the electron is also predicted, and found to be slightly aspherical on the order of an oblate ellipsoid. This shape is attributed to centrifugal force and compliant outer shell material. It is interesting to note that all of the electron’s attributes, both external and internal, with the exception of mass and angular moment, are functions of the fine structure constant a, and can be calculated from just three additional constants: electron mass, Planck’s constant, and speed of light. In particular, the ratios of the outer shell charge and mass to the electron charge and mass, respectively, are 3/2a. The ratios of the central core charge and mass to the electron charge and mass, respectively, are 1-(3/2a). Attributes of the electron are compared with those of the muon. Charge and spin angular momentum are the same, while mass, magnetic moment, and radius appear to be related by the fine structure constant. The mass of the electron outer shell is nearly equal to the mass of the muon. The muon internal structure can be modeled exactly the same as for the electron, with exactly the same attribute relationships.

The fragmentation and its mechanism of the uncoupled charge structure with segmental explosive

Charge structure, which can instantly release much energy, is a significant research point in explosive protection and warhead. The distribution of the fragment velocity from uncoupled charge structures with segmental shaped explosive were studied. Numerical calculation research was carried out based on the CEL method. The X-ray photographic images of fragmentation were obtained from explosion experiment, which provided experimental support for numerical simulation research. The results show that the fragmentation and velocity distribution of the charge structure with segmental explosive show obvious segmental characteristics compared with the traditional cylindrical shell charge. The explosive loadings of the shell under uncoupled conditions is not only determined by the detonation wave and the static pressure of the detonation products but by the impact dynamic pressure of the detonation products at low pressure and high speed and the static pressure generated by the detonation products expansion and convergence, leading to the significant difference among the coupled side, the uncoupled side and the transition area. In this paper, the fragmentation and velocity distribution of the charge with segmental explosive was obtained, the uncoupled explosive driving mechanism was investigated and verified. The conclusion provides a foundation for exploring and establishing the uncoupled explosive driving theory.

Numerical simulation and experimental study of the damage law of EFP warhead charging of cylindrical shells under different angles

In this paper, LS-dyna software was used to simulate the charging process of cylindrical shell when EFP has different angles, and some interesting phenomena and laws were found. Cylindrical elastic wave σr was generated when the cylindrical shell was impacted by EFP. The cylindrical elastic wave σr was correlated with the time required for the cylindrical shell charge to be successfully detonated. When the EFP warhead penetration Angle θ ranges from 0° to 10°, the σr increases linearly with (cosθ)-1/2. With the increase of θ, the tangential velocity vy had an obvious effect on the impact of EFP on the cylindrical shell, and the linear relationship between the elastic wave σr and (cosθ)-1/2 does not change. When the θ was greater than 45°, EFP could not successfully impact and detonate the cylindrical shell charge. The EFP velocity was measured by velocity measurement method with an error of 1.3%. The experimental results have strong similarity with the simulation results, indicating that the parameters of the numerical simulation model have good reliability.

Coherent vibrational dynamics of Au144(SR)60 nanoclusters.

The coherent vibrational dynamics of gold nanoclusters (NCs) provides important information on the coupling between vibrations and electrons as well as their mechanical properties, which is critical for understanding the evolution from a metallic state to a molecular state with diminishing size. Coherent vibrations have been widely explored in small-sized atomically precise gold NCs, while it remains a challenge to observe them in large-sized gold NCs. In this work, we report the coherent vibrational dynamics of atomically precise Au144(SR)60 NCs via temperature-dependent femtosecond transient absorption (TA) spectroscopy. The population dynamics of Au144(SR)60 consists of three relaxation processes: internal conversion, core–shell charge transfer and relaxation to the ground state. After removing the population dynamics from the TA kinetics, fast Fourier transform analysis on the residual oscillation reveals distinct vibrational modes at 1.5 THz (50 cm−1) and 2 THz (67 cm−1), which arise from the wavepacket motions along the ground-state and excited-state potential energy surfaces (PES), respectively. These results are helpful for understanding the physical properties of gold nanostructures with a threshold size that lies in between those of molecular-like NCs and metallic-state nanoparticles.

Highly Soluble Supertetrahedra upon Selective Partial Butylation of Chalcogenido Metalate Clusters in Ionic Liquids

AbstractSupertetrahedral clusters have been reported in two generally different types so far: one type possessing an organic ligand shell, no or low charges, and high solubility, while the other cluster type is ligand‐free with usually high charges and low or no solubility in common solvents. The latter is a tremendous disadvantage regarding further use of the clusters in solution. However, as organic substituents usually broaden the HOMO–LUMO gaps, which cannot be overcompensated by the (limited) cluster sizes, a full organic shielding comes along with drawbacks regarding opto‐electronic properties. We therefore sought to find a way of generating soluble clusters with a minimum number of organic substituents. Here, we present the synthesis and full characterization of two salts of [Sn10O4S16(SBu)4]4− that are high soluble in CH2Cl2 or CH3CN, which includes first NMR and mass spectra obtained from solutions of such salts with mostly inorganic supertetrahedral clusters. The optical absorption properties of this new class of compounds indicates nearly unaffected band gaps. The synthetic approach and the spectroscopic findings were rationalized and explained by means of high‐level quantum chemical studies.

Computer simulation of MEFP forming and the impact initiation of shell-covered cylindrical charge

In order to obtain the MEFP with smaller divergence angle for the apply in the destruction of unexploded ordnance, LS-DYNA numerical simulation software was used to simulate the formation process and motion state of the projectile formed by the integrated MEFP warhead. The influence of the parameters of the liner (thickness, radius of curvature) and the initiation mode (single and multi-point initiation) on the formation characteristics of MEFP were studied. After the optimization design of warhead, the simulation model of MEFP interact with shell-covered cylindrical charge was established to estimate the damage power. The optimized MEFP has small divergence angle and can detonate the shell charge with a thickness of 10 mm.

Numerical simulation of jet formation and penetration characteristics in multi-point initiation mode

In order to explore the application feasibility and effective gain of shaped charge jet under multi-point initiation system, the jet forming characteristics of 40 mm diameter shaped charge under multi-point initiation mode were analyzed, and the influence rules of the number of initiation points and initiation radius on jet parameters were obtained. The simulation results of jet penetrating cylindrical shell covered charge show that the multi-point initiation system can effectively improve the jet tip velocity and the length of the jet, which can effectively improve the impact initiation ability of the shell charge.

Understanding contact electrification at liquid\u2013solid interfaces from surface electronic structure

The charge transfer phenomenon of contact electrification even exists in the liquid–solid interface by a tiny droplet on the solid surface. In this work, we have investigated the contact electrification mechanism at the liquid–solid interface from the electronic structures at the atomic level. The electronic structures display stronger modulations by the outmost shell charge transfer via surface electrostatic charge perturbation than the inter-bonding-orbital charge transfer at the liquid–solid interface, supporting more factors being involved in charge transfer via contact electrification. Meanwhile, we introduce the electrochemical cell model to quantify the charge transfer based on the pinning factor to linearly correlate the charge transfer and the electronic structures. The pinning factor exhibits a more direct visualization of the charge transfer at the liquid–solid interface. This work supplies critical guidance for describing, quantifying, and modulating the contact electrification induced charge transfer systems in triboelectric nanogenerators in future works.

Вплив діаметра електродних порошкових дротів на механічні характеристики електродугових покриттів

The influence of the diameter of the electrode flux-cored wires on the mechanical characteristics of the electric arc coatings is carried out in the work. Electric arc coatings were obtained on the original equipment, developed and manufactured at the Institute of Physics and Mechanics. GV Karpenko NAS of Ukraine. For spraying, model flux-cored wires of basic doping systems Fe – Cr – C and Fe – Cr – B with a diameter of 1.6 and 2.4 mm were used. The influence of the diameter of flux - cored wires on the structure, electric arc coatings from model flux - cored wires of different diameters is investigated. The dependence of porosity, microhardness, adhesion to the steel base, abrasive wear resistance of electric arc coatings sprayed from flux-cored wires with different amounts of charge on the thickness of the lamellae in the coating structure has been established. The influence of the thickness of the lamellae in the structure of coatings sprayed from flux-cored wires with different amounts of charge (depending on their diameter 1.6 and 2.4 mm) on their abrasive wear resistance was determined. It was found that the thickness of the lamellae in the coatings of all analyzed alloying systems increased with increasing volume of molten metal at the ends of flux-cored wires with the corresponding formation of droplets of larger diameter during its dispersion by air jet. shell charge and high arc current. It is shown that the amount of oxide phase in the structure of coatings doubles with increasing spray distance of flux-cored wires from 80 to 120 mm. More oxide phase (40… 100%) was found in coatings formed of flux-cored wires with a diameter of 2.4 mm with a higher filling factor of its shell charge compared to coatings formed of flux-cored wires with a diameter of 1.6 mm with lower filling. This is due to the larger volume of the charge in the powder wires of larger diameter, the cavities between the powders in which are filled with air, which intensively oxidizes the melt droplets inside the powder wires and at their ends during spraying. It is established that the porosity and microhardness of coatings from the developed flux-cored wires increase with the increase of the thickness of the lamellae in their structure and, accordingly, the diameter of the flux-cored wires. The increase in micro hardness is due to less evaporation and burnout of alloying elements from the droplets forming the coating, and the increase in porosity is caused by intensive spraying of droplets when hitting the sprayed surface, which contributes to micro cavities between the lamellae of the coating. It was found that with increasing the thickness of the lamellae in the structure of coatings of flux-cored wires 250H21VFGS and flux-cored wires 50HN2R5GS their adhesion to the steel base decreased slightly due to the occurrence of tensile stresses in coatings, which cause micro cracks or cracks. At the same time, the adhesion of 50X6MG2C flux-cored wire coatings to steel increased due to the higher carbon content of large lamellae and favorable conditions for the formation of high-carbon martensite, which has the lowest coefficient of thermal expansion and causes the lowest residual tensile stresses. It was found that the abrasive and gas-abrasive wear resistance of coatings from flux-cored wires 250Х21ВФГС decreased, and from flux-cored wires 50ХН2Р5ГС increased due to the increase in the thickness of the lamellae in their structure using a larger diameter.

Inducing ferromagnetism in surface stabilised intrinsic CdSe nanoparticles by a simple process

In this letter, we report a simple process to derive in situ surface stabilised intrinsic CdSe nanoparticles (NPs) showing room temperature ferromagnetism (RTFM). The observed RTFM is primarily attributed to the lattice strain (ε) in the NPs supported by an effective core (CdSe)-shell (surface layer) charge transfer mechanism. The synthesis method allows precise control over particle morphology and dispersity, and is highly convenient in tuning the magnetic properties for pertinent applications. Highlights Magnetic CdSe nanoparticles were synthesized by a facile process. In situ formed graphitic-carbon layer on the surface stabilises the nanoparticles. The process permits precise control over particle morphology and dispersity. The technique is also convenient in tuning the magnetic properties. Monodispersed magnetic CdSe nanoparticles have potential applications in modern optoelectronics.

Insight into the Bonding and Aggregation of Alkyllithiums by Experimental Charge Density Studies and Energy Decomposition Analyses.

In this Article, the organolithiums [((-)-sparteine)LitBu] (1), [(ABCO)LitBu]2 (2), and [(ABCO)2(LiiPr)4] (3) are investigated by means of experimental and theoretical charge density determination to elucidate the nature of the Li-C and Li-N bonds. Furthermore, the valence shell charge concentrations (VSCCs) in the nonbonding region of the deprotonated Cα-atom will provide some insight on the localization of the carbanionic lone pair. Analysis of the electron density (ρ(rBCP)), Laplacian (∇2ρ(rBCP)), and the energy decomposition (EDA) confirmed that the Li-C/N bond exhibits astonishingly similar characteristics, to reveal an increasingly polar contact with decreasing aggregate size. This explains former observations on the incorporation of halide salts in organolithium reagents. Furthermore, it could be shown that the bonding properties of the iPr group are similar to those of the tBu substituent. The accuracy of fit to all previously determined properties in organolithiums is remarkable.

Peculiarity of Electric Properties of Oxygen‐Implanted Silicon at Early Precipitation Stages

The evolution of the defect structure and electric properties of the oxygen‐implanted silicon samples subjected by thermal treatment in the temperature range from 700 to 1100 °C is investigated using transmission electron microscopy (TEM) and space charge spectroscopy. It is established that embedded positive charge of oxygen precipitates (OPs) decreases inversely proportional to their size. This fact gives evidence about localization of the charge in thin nonstoichiometric shell of OP. Annealing at 700 °C results in the formation of nanosized defects and in an inhomogeneous electric structure of the implanted region: the embedded positive charge is localized in the near‐surface vacancy‐rich part of the implanted region, whereas the strongly compensated layer is formed in self‐interstitial‐rich deepest part of the implanted region.

Bayesian Network Resource for Meta-Analysis: Cellular Toxicity of Quantum Dots.

A web-based resource for meta-analysis of nanomaterials toxicity is developed whereby the utility of Bayesian networks (BNs) is illustrated for exploring the cellular toxicity of Cd-containing quantum dots (QDs). BN models are developed based on a dataset compiled from 517 publications comprising 3028 cell viability data samples and 837 IC50 values. BN QD toxicity (BN-QDTox) models are developed using both continuous (i.e., numerical) and categorical attributes. Using these models, the most relevant attributes identified for correlating IC50 are: QD diameter, exposure time, surface ligand, shell, assay type, surface modification, and surface charge, with the addition of QD concentration for the cell viability analysis. Data exploration via BN models further enables identification of possible association rules for QDs cellular toxicity. The BN models as web-based applications can be used for rapid intelligent query of the available body of evidence for a given nanomaterial and can be readily updated as the body of knowledge expands.

Core–Shell Charge Transfer in Plasmonic Fe@Ag Nanoparticles on MgO Film

In this work we report the interfacial charge transfer between the Fe core and Ag shell in self-organized nanoparticles on MgO films on Mo(001). Predeposited Fe nanoparticles organize in a square n...

Effect of Shell Material on the Detonation of an Explosive Charge

The effect of shell material (copper and silicon carbide) on the detonation of a cylindrical explosive charge was analyzed. The wave patterns in the detonation products and the shells are substantially different, which is due to different sound velocities and the rapid destruction of the ceramic under explosive loading. The wave pattern at the explosive/ceramic interface was found to be affected by desensitization of the explosive due to its loading by an advancing wave from the shell side, resulting in a decrease in pressure, blurring of the detonation front, and an increase in particle velocity. Throughout the process, there is a continuous increase in the time of explosive decomposition near the interface between the explosive and the ceramic shell. An extended region with a constant pressure close to the Chapman–Jouguet pressure was observed on the axis of symmetry behind the detonation front of the explosive charge in the ceramic shell.

Structure of [60]fullerene with a mobile lithium cation inside.

The structure of crystalline [60]fullerene with a lithium cation inside (Li+@C60) was determined by synchrotron radiation X-ray diffraction measurements to understand the electrostatic and thermal properties of the encapsulated Li+ cation. Although the C60 cages show severe orientation disorder in [Li+@C60](TFPB−)·C4H10O and [Li+@C60](TFSI−)·CH2Cl2, the Li+ cations are rather ordered at specific positions by electrostatic interactions with coordinated anions outside the C60 cage. The Li+@C60 molecules in [Li+@C60](ClO4−) with a rock-salt-type cubic structure are fully disordered with almost uniform spherical shell charge densities even at 100 K by octahedral coordination of ClO4− tetrahedra and show no orientation ordering, unlike [Li+@C60](PF6−) and pristine C60. Single-bonded (Li+@C60−)2 dimers in [Li+@C60−](NiOEP)⋅CH2Cl2 are thermally stable even at 400 K and form Li+–C bonds which are shorter than Li+–C bonds in [Li+@C60](PF6−) and suppress the rotational motion of the Li+ cations.

Controlling the Growth of Staphylococcus epidermidis by Layer-By-Layer Encapsulation.

Commensal skin bacteria such as Staphylococcus epidermidis are currently being considered as possible components in skin-care and skin-health products. However, considering the potentially adverse effects of commensal skin bacteria if left free to proliferate, it is crucial to develop methodologies that are capable of maintaining bacteria viability while controlling their proliferation. Here, we encapsulate S. epidermidis in shells of increasing thickness using layer-by-layer assembly, with either a pair of synthetic polyelectrolytes or a pair of oppositely charged polysaccharides. We study the viability of the cells and their delay of growth depending on the composition of the shell, its thickness, the charge of the last deposited layer, and the degree of aggregation of the bacteria which is varied using different coating procedures-among which is a new scalable process that easily leads to large amounts of nonaggregated bacteria. We demonstrate that the growth of bacteria is not controlled by the mechanical properties of the shell but by the bacteriostatic effect of the polyelectrolyte complex, which depends on the shell thickness and charge of its outmost layer, and involves the diffusion of unpaired amine sites through the shell. The lag times of growth are sufficient to prevent proliferation for daily topical applications.

Unmasking the Mechanism of Structural Para- to Ferroelectric Phase Transition in (NH4)2SO4.

New nontoxic and biocompatible ferroelectric materials are a subject undergoing intense study. One of the most promising research branches is focused on H-bonded organic or hybrid ferroelectrics. The engineering of these materials is based on mimicking the phase transition mechanisms of the well-known inorganic ferroelectrics. In our study, a coupled experimental and theoretical methodology was used for a precise investigation of the ferroelectric phase transition mechanism in ammonium sulfate (AS). A series of single-crystal X-ray diffraction measurements were performed in the temperature range between 273 and 163 K. The detailed inspection of the obtained static structural data, in the above-mentioned temperature range, allowed us to reveal dynamical effects at the ferroelectric phase transition. Accurate analysis of all geometrical features within the obtained crystal structures was carried out. The results were discussed in the view of previously discovered physical properties. X-ray studies were complemented by the use of quantum theory of atoms in molecules calculations and Hirshfeld surface analysis. Valence shell charge concentration analysis allowed us to find the subtle changes between charge density distribution within SO42- in para- and ferroelectric phases. H-bond interactions, geometrically classified in both AS phases, were all confirmed by the appropriate critical points. The interaction energies were estimated for the structures at 273, 233, 213, 183, and 163 K. Correlation between the geometrical approach and the results of theoretical calculations enabled us to discover the differences in interaction equilibrium between the AS phases. The mechanism of the phase transition originates from the disruption of the vibrational lattice mode between sulfate anions. Our studies resolved the problem, which was under discussion for more than 60 years.