Solid Density Research Articles

Cd(II) and As(V) removal from the multicomponent solutions in the presence of ionic polymers using carbonaceous adsorbents obtained from herbs

Abstract Biochars and activated carbons obtained from the nettle and the sage herbs were used for Cd(II), As(V), poly(acrylic acid) and polyethylenimine simultaneous adsorption from the multicomponent aqueous solutions. Electrokinetic studies proved that both activated carbons show acidic character of the surface. The point of zero charge of the sample obtained from the nettle herb occurs at pH 3.1, whereas that of the adsorbent obtained from the sage herb at pH 4.0. Cd(II) adsorption causes the decrease in the surface charge density and the zeta potential of both activated carbons, whereas As(V) addition results in the increase of solid surface charge density and its impact on the zeta potential value depends on adsorbent type. In case of the simultaneous presence of metals and polymers, the adsorbed macromolecules have greater influence on the surface charge density and the zeta potential values than the metal ions. Cd(II) and As(V) are well adsorbed on the examined activated carbons irrespective of the solution pH (changing in the range 3–9). Maximum adsorption were 218.27 mg/g for Cd(II) and 205.53 mg/g for As(V). The polymers presence causes a decrease (80–90 %) of both metal ions adsorbed amounts, whereas the poly(acrylic acid) and polyethylenimine adsorption mechanism in the presence of cadmium and arsenic ions depends on the adsorbent type and polymer-metal interactions.

Inner edges of planetesimal belts: collisionally eroded or truncated?

ABSTRACT The radial structure of debris discs can encode important information about their dynamical and collisional history. In this paper, we present a three-phase analytical model to analyse the collisional evolution of solids in debris discs, focusing on their joint radial and temporal dependence. Consistent with previous models, we find that as the largest planetesimals reach collisional equilibrium in the inner regions, the surface density of dust and solids becomes proportional to ∼r2 within a certain critical radius. We present simple equations to estimate the critical radius and surface density of dust as a function of the maximum planetesimal size and initial surface density in solids (and vice versa). We apply this model to Atacama Large Millimeter/submillimeter Array observations of seven wide debris discs. We use both parametric and non-parametric modelling to test if their inner edges are shallow and consistent with collisional evolution. We find that four out of seven have inner edges consistent with collisional evolution. Three of these would require small maximum planetesimal sizes below 10 km, with HR 8799’s disc potentially lacking solids larger than a few centimetres. The remaining systems have inner edges that are much sharper, which requires maximum planetesimal sizes ≳ 10 km. Their sharp inner edges suggest they could have been truncated by planets, which JWST could detect. In the context of our model, we find that the seven discs require surface densities below a Minimum Mass Solar Nebula, avoiding the so-called disc mass problem. Finally, during the modelling of HD 107146 we discover that its wide gap is split into two narrower ones, which could be due to two low-mass planets formed within the disc.

Binary mixtures of biomass and inert components in fluidized beds: Experimental and neural network exploration

In light of the little understanding of the hydrodynamics of multicomponent particle beds involving biomass, a detailed investigation has been performed, which combines well-known experimental and theoretical approaches, relying, respectively, on conventional pressure drop methods and artificial neural network (ANN) techniques. Specific research tasks related to this research includes: i. to experimentally investigate by means of visual observation the mixing and segregation behavior of selected binary mixtures by varying the biomass size and shape as well as the properties (size and density) of the granular solids in cold flow experiments; ii. to carry out a systematic experimental investigation on the effect of the biomass weight and volume fractions on the characteristic velocities (i.e., complete fluidization velocities and minimum slugging velocity) of the investigated binary mixtures in order to select the critical weight fraction of biomass in the mixtures beyond which the fluidization properties deteriorate (e.g., channelling, segregation, slugging); iii. to analyze the results obtained in about 80 cold flow experiments by means of ANN techniques in order to scrutinize the key factors that influence the behavior and the characteristic properties of binary mixtures. Experimental results suggest that the bed components’ density difference prevails over the size difference in determining the mixing/segregation behavior of binary fluidized bed, whereas the velocities of minimum and complete fluidization increased with the increase of the biomass weight fraction in the bed. The training of ANNs demonstrated good performances for both outputs (Umf and Ucf), in particular, best predictions have been obtained for Umf with a MAPE < 4% (R2 = 0.98), while for Ucf the best ANN returned a MAPE of about 7% (R2 = 0.93). The analysis on the importance of single input on ANN predictions confirms the importance of particle density of the bed components. However, unexpected results showed that morphological features of biomass have a limited importance on Ucf.

Modeling density effects on electronic configurations in warm dense plasmas

We present a method to calculate the shift of the K edge in warm dense aluminum. We use the average-atom model and show how to build the energy of an electronic configuration with integer subshell populations and by taking into account the interaction of the bound electrons with the free electrons. We successfully compare our calculation of the spectral opacity with the Henke table for aluminum at solid density and 300 K. We found a redshift of the K edge along the principal Hugoniot consistent with experimental data. We also compute the 2s and 2p edges. We obtain L edge redshifts similar to the K edge redshift.

Cooling Rates of Chondrules after Lightning Discharge in Solid-rich Environments

Among the several candidate models for chondrule formation, the lighting model has been recognized to be less likely than the other two major models, shock-wave heating and planetesimal collision. It might be because we have believed that the lightning model predicts cooling rates of chondrules that are too fast to reproduce their textures with the assumption that the discharge channels must be optically thin. However, the previous works revealed that the buildup of a strong electric field to generate the lightning in protoplanetary disks requires the enhancement of the solid density. Moreover, some properties of chondrules indicate their formation in environments with such a high solid density. Therefore, the discharge channels may be optically thick, and the lightning model can potentially predict the proper cooling rates of chondrules. In this study, we reinvestigate the cooling rates of chondrules produced by the lightning in the solid-rich environments considering the radiative transfer and the expansion of the hot channel. Chondrules must interact dynamically with the surrounding gas and dust via the drag force. We consider two limiting cases for the dynamics of chondrules: the drag force is ignored in the first case, and chondrules are completely coupled with their surroundings in the second case. In both cases, the lightning model predicts the proper cooling rates of chondrules under the optically thick conditions with high solid enhancement. Therefore, the lightning model is worth further investigation to judge its reliability as the source of chondrule formation.

Research on Preparation and Performance of Aerogel Rock Wool Thermal Insulation Composite Materials

Reasearch and experimental tests had been operated on the preparation process and performance of aerogel rock wool composite thermal insulation material respectively, including the effects of solid contents, thickness and density of the board on thermal conductivity of the aerogel rock wool composite material, and the morphology and energy spectrum of the material were analyzed. The results showed that aerogel was beneficial to reduce the thermal conductivity of aerogel rock wool composite, and the thermal insulation performance of ordinary rock wool was greatly improved.

A Portable Device for On‐Site Measurement of Sediment Concentration Through Volume‐Mass Replacement

AbstractTo enable on‐site and near‐real‐time sediment concentration measurements, a novel type of portable device with a constant volume sampling bottle was developed in this study. The device consisted of a sampling bottle, a measuring assembly, and a platform for auxiliary data management. Five representative soils and eight sediment concentrations were used to validate the device accuracy and application. Moreover, a novel concept of sediment effective density (SED) was proposed. Under SED, a linear regression was fit between the measured and actual sediment concentrations. The results revealed that the slopes of the fitting line were close to 1, and the R2 values were greater than 0.999 for five soils. Moreover, for total samples, the root mean square error (RMSE) and Nash–Sutcliffe efficiency coefficient (NSE) values were 5.59 g/L and 0.9996, respectively. Additionally, an average SED of 2.51 g/cm3 was calculated in this study. With an average soil SED of 2.51 g/cm3 and an average soil solid density of 2.65 g/cm3, the RMSE and NSE were 11.85 and 18.50 g/L and 0.9981 and 0.9954, respectively. This result demonstrated that the designed device accurately measured sediment concentration under various conditions. Furthermore, relative to the traditional oven‐drying method, the device could measure sediment concentration near‐real‐time and with high accuracy, which could be useful for researchers with excellent potential. It was recommended to measure the SED in a laboratory or runoff plot because the sediment sources could be identified and obtained. In a field or river, it was recommended to use 2.51 g/cm3 as the SED, which was more accurate than 2.65 g/cm3.

Solar-driven calcium looping in fluidized beds for thermochemical energy storage

Integration between Concentrated Solar Power (CSP) and Calcium Looping (CaL) is gaining consideration in the perspective of large shares of renewable energy sources, to smooth the variability of non-dispatchable energy input. The scope of this study is to investigate the CaL process for ThermoChemical Energy Storage (TCES), by performing a dedicated experimental campaign in fluidized bed under realistic process conditions suitable for CaL-CSP integration. Chemical deactivation of the limestone-based sorbent has been assessed by measuring the extent of Ca carbonation along iterated calcination/carbonation cycles, correlated with physico-chemical characterization of the sorbent at selected stages of the conversion. Properties that have been scrutinized were particle size distribution, bulk density, and particle size, density, and porosity of bed solids. The attainable values of energy storage density were evaluated as well.A remarkable finding of the experimental campaign is the pronounced synergistic deactivation of limestone when it is co-processed with silica sand. Chemical interaction of CaO with the silica sand constituents at the process temperatures has been scrutinized as possible responsible for the loss of reactive CaO toward CO2 uptake. Post-process of particle density data, together with N2-intrusion porosimetric analysis, and quantitative and qualitative XRD analyses, suggests that the sand/lime interaction induces a strong reduction of the total and reactive sorbent porosity and, in turn, of reactivity.Density-based classification to separate converted and unconverted limestone particles after the carbonation step has been evaluated with the goal of increasing process efficiency, by avoiding the circulation of streams with unreacted particles through the plant. For this purpose, the minimum fluidization velocity of calcined and carbonated particles has been measured after each reaction step at the relevant process temperature.

On a modified Korteweg–de Vries equation for electrostatic structures in relativistic degenerate electron–positron plasma

In this paper, the propagation of acoustic solitons in an electron–positron (e–p) degenerate plasma with the relativistically degenerate electrons and positrons is studied. Moreover, we considered stationary positive ions for neutralizing the plasma background. Using the reductive perturbation method, we obtained a modified Korteweg–de Vries equation. By applying a Jacobi elliptic function expansion method, we have proposed the exact analytical solitary, kink, and periodic solutions for the nonlinear wave structures. Also, using the phase plane analysis three equilibrium points have been perceived two of them should be centers and the last is a saddle for quantum acoustic waves. The numerical and computational results show that firstly some of them should be discarded by physical values and then these solutions have been influenced by the plasma parameters such as the electron degenerate density parameter (ne0) and the ion-to-electron density ratio (δ) which peaked out in white dwarf stars. It is found that both the amplitude and the width of the nonlinear structures are affected by the mentioned parameters. This investigation is useful for the relativistically degenerate plasma media in ultra-dense astrophysical environments (such as neutron stars, white dwarfs, etc.), inertia fusion science, experiments involving the interaction of laser and solid density plasma, and inertial confinement fusion in which the relativistic effects play a major role.

Evolution of mixing length empirical equation for recouping of heat from industrial waste flue gases using air‐quarry dust/iron ore

AbstractIndustry processes require large amounts of energy inputs and often generate high temperatures exit gases that can potentially serve as secondary sources of energy. Waste heat recovery offers an opportunity for energy conservation that deserves more attention in the current global effort. Recovery of such waste heat can result in substantial reductions in net energy demand. Based on these objectives, this report describes the result of an experimental study that used solid particles in a vertical riser to recover gas energy from hot air through co‐current contact with solid particles. To study the hydrodynamic aspects of the riser section, this study utilized a fabricated experimental apparatus similar to the vertical duct used in the cement industry. The purpose of this study is to collect hydrodynamic data because there is limited information available about these aspects in the literature. A metallic fluid particle heat exchanger has been investigated through experiments. Various sizes of quarry dust and iron ore particles are studied in the present study. An empirical correlation is used to fit the mixing length (LA) determined at different parametric levels (gas velocity, particle size, solid feed rate, and solid density). Experimental correspondence for mixing length or LA is given as . The constructed experimental setup demonstrates a suspension preheater (SP) used in modern cement plants, but the correlation can be extended to a variety of other industries where waste heat recovery is feasible.

Two-Dimensional Plasmons in Laterally Confined 2D Electron Systems.

The collective oscillations of charge density (plasmons) in conductive solids are basic excitations that determine the dynamic response of the system. In infinite two-dimensional (2D) electron systems, plasmons have gapless dispersion covering a broad spectral range from subterahertz to infrared, which is promising in light-matter applications. We discuss the state-of-the-art physics of 2D plasmons, especially in confined 2D electron systems in stripe and disk geometry, using the simplest approach for conductivity. When the metal gate is placed in the vicinity of the 2D electron system, an analytical description of the plasmon frequency and damping can be easily obtained. We also analyze gated plasmons in the disk when it was situated at various distances from the gate, and discuss in detail the nontrivial behavior of the damping. We predict that it is not a simple sum of the radiative and collisional dampings, but has a nonmonotonic dependence on the system parameters. For high-mobility 2D systems, this opens the way to achieve the maximal quality factor of plasma resonances. Lastly, we discuss the recently discovered near-gate 2D plasmons propagating along the laterally confined gate, even without applied bias voltage and having gapless dispersion when the gate has the form of a stripe, and discrete spectrum when the gate is in the form of disk. It allows for one to drive the frequency and spatial propagation of such plasmons.

Construction of a geoecological map of dust particles transfer from the surface of the Shymkent lead (plumbum) factory dump

The study of horizontal migration of heavy metals is relevant for Shymkent city. In 1934, lead processing began, and sludge waste was stored on the territory of the lead factory. Ameliorative or other structures capable of reducing dust emissions have not been built around the lead dump, allowing lead dust to freely spread over long distances from the SPZ (sanitary protection zone). In this article, the horizontal migration of lead dust was studied based on climatic and calculated data by building a physical model; in addition, a geoecological map was built. This work has practical significance for further ecological and geochemical assessment of soils for the content of heavy metal concentrations, since it visually characterizes the spread of lead dust along the wind rose. To build a geoecological map of the transfer of impurities, we are faced with the task of determining the rate of settling of hovering particles and their distributions depending on the masses of particles and wind speed. To determine the rate of deposition of lead particles in the atmosphere, we need to study the shape of lead, background meteorological situation, particle diameter, solid particle density, medium density and dynamic viscosity of the medium. The removal of dust particles from the surfaces of ash and slag dumps of industrial facilities into the atmosphere under the influence of wind erosion, followed by their deposition on the soil, is one of the most common ways of polluting the territories of industrial facilities. As a result of the calculations, the surface concentration of dust particles was derived and a geoecological map was compiled. Keywords: geoecological map, lead dumps, assessment of dust emissions, horizontal migration of heavy metals, physical model of transport and scattering.

Ultrafast time-resolved 2D imaging of laser-driven fast electron transport in solid density matter using an x-ray free electron laser.

High-power, short-pulse laser-driven fast electrons can rapidly heat and ionize a high-density target before it hydrodynamically expands. The transport of such electrons within a solid target has been studied using two-dimensional (2D) imaging of electron-induced Kα radiation. However, it is currently limited to no or picosecond scale temporal resolutions. Here, we demonstrate femtosecond time-resolved 2D imaging of fast electron transport in a solid copper foil using the SACLA x-ray free electron laser (XFEL). An unfocused collimated x-ray beam produced transmission images with sub-micron and ∼10fs resolutions. The XFEL beam, tuned to its photon energy slightly above the Cu K-edge, enabled 2D imaging of transmission changes induced by electron isochoric heating. Time-resolved measurements obtained by varying the time delay between the x-ray probe and the optical laser show that the signature of the electron-heated region expands at ∼25% of the speed of light in a picosecond duration. Time-integrated Cu Kα images support the electron energy and propagation distance observed with the transmission imaging. The x-ray near-edge transmission imaging with a tunable XFEL beam could be broadly applicable for imaging isochorically heated targets by laser-driven relativistic electrons, energetic protons, or an intense x-ray beam.

Finite-temperature Thomas–Fermi–Dirac-Weizsäcker model in the warm dense matter regime

The Thomas–Fermi–Dirac-Weizsäcker model for finite temperature is presented. Starting with the free energy density, consistent expressions for the Helmholtz free energy, total energy, pressure and virial theorem are derived. The exchange and correlation terms are cast in a form that is suitable for derivation of their contributions to energy and pressure. The Euler–Lagrange equation is written in Schrödinger-like form and solved in spherical symmetry in a Wigner–Seitz cell. The challenges associated with its numerical solution are discussed and a viable approach to obtain a non-negative solution is proposed. The model is benchmarked for two materials, Al and Cu, by comparing the pressure at solid density in the temperature range , as well as the cold pressure curves.

Probing bulk electron temperature via x-ray emission in a solid density plasma

Bulk electron temperatures are calculated for thin Cu targets irradiated by the petawatt class Vulcan laser, from the Kα yield obtained using highly oriented pyrolytic graphite crystals. Cu-Kα emission studies have been used to probe the bulk electron temperature. A 30–80 eV core temperature extends homogeneously over distances up to ten times the laser focal spot size. Energy shifting has been observed due to different ionization states produced for different temperatures in the plasma. Polarization dependencies of plasma temperature are observed through the production of x-rays in different targets. 2D PIC simulations were performed to measure the polarization dependency of bulk electron temperature, which supports our experimental results. This paper could be of importance in understanding the different behavior of laser coupling at different polarizations and their role in x-ray production.

Feasibility of Using Poisons to Suppress the Positive Temperature Reactivity Coefficient in Hydride-Moderated Reactors

Metal hydrides are being seriously considered for advanced nuclear reactor or microreactor applications due to their solid physical state and high hydrogen density. Using hydrides for autonomous applications poses several research and development challenges, one of which relates to neutron upscattering in the thermal energy regime. These hydrides, including zirconium hydride and yttrium hydride, result in a positive temperature coefficient of reactivity for several advanced reactor designs. In this study, we consider one such design that exhibits positive feedback from metal hydrides and thoroughly investigate the neutronic aspects of the core. Temperature reactivity coefficients for four fuels and two hydride moderator configurations are studied, and the total temperature coefficients are found to be positive for all designs, showing that this issue cannot be resolved simply by material variations. Accordingly, five epi-thermal absorbers were evaluated to demonstrate the feasibility of the excess positive feedback suppression in the core instigating from neutron energy spectrum shift. Following which, two promising burnable poison candidates are selected to investigate further throughout the core discharge. Promising results are shown for this core design, which can be extended to other hydride-moderated remote special-purpose reactor designs.

A material-sparing simplified buoyancy method for determining the true density of solids

True density is an important physical property of powdered materials, especially in the context of powder compaction. Currently available methods for true density determination either require a significant amount of materials or are laborious. Hence, a material-sparing and efficient method for true density determination is of value. In this work, we detail a simplified buoyancy-based method capable of fast determination of true density with accuracy comparable to helium pycnometry. This miniaturized method only uses a few milligrams of a powder with data collection process expedited by centrifugation in a laboratory centrifuge. This method can be easily adapted in a laboratory since determination of true density only requires a balance, a micropipette, a laboratory centrifuge, and standard stock liquids of low and high densities. Hence, it is a useful addition to the materials characterization tool kit critical for pharmaceutical formulation development.

A zinc-conducting chalcogenide electrolyte

A solid-state zinc-ion battery can fundamentally eliminate dendrite formation and hydrogen evolution on the zinc anode from aqueous systems. However, enabling fast zinc ion + conduction in solid crystals is thought to be impossible. Here, we demonstrated a fluorine-doping approach to achieving fast Zn2+ transport in mesoporous ZnyS1-xFx. The substitutional doping of fluoride ion with sulfide substantially reduces Zn2+ migration barrier in a crystalline phase, while mesopore channels with bounded dimethylformamide enable nondestructive Zn2+ conduction along inner pore surface. This mesoporous conductor features a high room-temperature Zn2+ conductivity (0.66 millisiemens per centimeter, compared with 0.01 to 1 millisiemens per centimeter for lithium solid-state electrolyte) with a superior cycling performance (89.5% capacity retention over 5000 cycles) in a solid zinc-ion battery and energy density (0.04watt-hour per cubic centimeter) in a solid zinc-ion capacitor. The universality of this crystal engineering approach was also verified in other mesoporous zinc chalcogenide materials, which implies various types of potential Zn2+-conducting solid electrolytes.

Modeling of Physical and Compressive Test Properties of Tigernut Using Response Surface Approach

The Engineering data of tiger nut cultivated in Africa is of high importance in facilitating the design of machineries for its effective and efficient cultivation, processing, handling, storage, and postharvest activities in general. This study is aimed at determining and modeling of the physical and compressive test properties of tiger nuts as influenced by size, moisture level and loading pattern. Applying Standard procedures and a 3,4,3 response surface factorial design, the Tiger nuts were cleaned of all foreign materials and sorted into three different sizes of 6mm, 9mm and 12mm, and conditioned into four different moisture levels of 7%, 10%, 13% and 16% respectively. The results shows that the arithmetic mean diameter (AMD) ranged from 7-14.867 (mm), geometric mean diameter (GMD) ranged from 6.982-14.853 (mm), sphericity (S) ranged from 0.931-1.011, surface area (SA) ranged from 153.216 -693.382 (mm2) and the aspect ratio (AR) ranged from 0.926-1.106. The mass (M) of 1000 tiger nut ranged from 201-1061 (g), volume (V) ranged from 25-96 (cm3), bulk density (BD) ranged from 0.634-0.979 (g/cm3), solid density (SD) ranged from 0.712-0.989 (g/cm3) and porosity (P) ranged from 11.08-21.45. The angle of repose ranged (AOR) from 20.58o-28.85o while the coefficient of friction (CF) on galvanized steel and stainless-steel surfaces ranged from 0.222-0.352 and 0.201-0.02 respectively. It was observed that, as sizes and moisture level increases, AMD, GMD, S, SA, AR, M, V, BD, SD and CF all increases respectively while both P and AOR decreases as the size and moisture level increases. It was revealed that the maximum compressive stress ranged from 0.26392-2.12026 (MPa), compressive strain at maximum compressive stress ranged from 1.20168-4.58292 (mm/mm). Energy at maximum compressive stress ranged from 0.02298-0.50274 (J), the compressive load at maximum compression stress ranged from 27.5937-232.257 (N), the extension at maximum compressive stress ranged from 0.30271-4.01056 (mm). The compressive stress at break ranged from 0.20376-1.75422 (MPa). The compressive load at break ranged from 25.2221-200.257 (N). The compressive strain at break ranged from 1.39935-5.79384 (mm/mm). The compressive extension at break ranged from 0.24417-3.55188 (mm). The energy at break ranged from 0.02113-0.33018 (J). The compressive stress at yield ranged from 0.24918-2.37054 (MPa) while the compressive load at yield ranged from 15.9373-210.693 (N). ANOVA result reveals that moisture level and tiger nut sizes have significant effects on the physical properties of tiger nut measured except on sphericity. Moisture level, tiger nut sizes and loading pattern have significant effects on the compressive test properties of tiger nut tested at 95% confidence level except for Energy at maximum compressive stress and Energy at break where loading have no significant effect at 95% confidence level. Empirical models were developed for the measured Engineering properties. The experimental data generated from this study serves as strong tools for the design and development of tiger nut postharvest machineries such as an oil and milk extractor among others.

Efficient generation of collimated multi-GeV gamma-rays along solid surfaces

Bright γ -ray sources are of great significance for fundamental research, medicine, and industry. However, γ -ray production by bremsstrahlung, Compton scattering, and synchrotron radiation is often subjected to large divergence, wide size, and/or low efficiency, making it difficult to achieve high-brightness γ -ray sources. Here, we have found an efficient mechanism to generate γ -rays with, to our knowledge, unprecedented brilliance by use of an ultrarelativistic electron beam with nC charge incident onto a solid surface at grazing incidence. With this interaction configuration, extreme high quasistatic magnetic fields up to the gigagauss level or effective electric fields up to 10 14 V / m are induced by the background electron backflows at the target surface. Subsequently, the electron beam is strongly focused by such fields by over an order of magnitude to submicrometer diameter, and its density is increased beyond the solid density; the induced effective fields are high enough to trigger quantum electrodynamics (QED) effects. These result in the production of extremely brilliant dense γ -ray beams with photon energy reaching multi-GeV, where the electron-to-photon energy conversion efficiency can exceed 60%. This offers a promising route to push the beam–target interaction to the QED regime, leading to ultrabright γ -ray sources for various applications.