Kinds Of Solids Research Articles

An equation of state based on the scaling properties of vibrational spectra at high pressure

Inter-atomic forces control vibrational properties and elastic moduli of a solid material. Based on first-principle calculations, it has been reported that, for elemental solids, the Debye frequency scales linearly with density to high accuracy. Combining this with other scaling properties of vibrational frequencies at high pressure, a new equation of state is presented. The proposed equation of state is tested against available experimental data for various kinds of solids at high pressure and room temperature. The quality of description of the compressional behavior of solids by our proposed equation of state is, for many cases, comparable to or better than that with the Vinet EOS.

Progress in Superlubricity Across Different Media and Material Systems—A Review

Superlubricity is a terminology often used to describe a sliding regime in which the adhesion leading to friction or resistance to sliding literally vanishes. For improved energy security, environmental sustainability, and a decarbonized economy, achieving superlubric sliding surfaces in moving mechanical systems sounds very exciting, since friction adversely impacts the efficiency, durability, and environmental compatibility of many moving mechanical systems used in industrial sectors. Accordingly, scientists and engineers have been exploring new ways to achieve macroscale superlubricity through the use of advanced materials, coatings, and lubricants for many years. As a result of such concerted efforts, recent developments indicate that with the use of the right kinds of solids, liquids, and gases on or in the vicinity of sliding contact interfaces, one can indeed achieve friction coefficients well below 0.01. The friction coefficient below this threshold is commonly termed the superlubric sliding regime. Hopefully, these developments will foster further research in the field of superlubricity and will ultimately give rise to the industrial scale realization of nearly-frictionless mechanical systems consuming far less energy and causing much-reduced greenhouse gas emissions. This will ultimately have a substantial positive impact on the realization of economically and environmentally viable industrial practices supporting a decarbonized energy future. In this paper, we will provide an overview of recent progress in superlubricity research involving solid, liquid, and gaseous media and discuss the prospects for achieving superlubricity in engineering applications leading to greater efficiency, durability, environmental quality, and hence global sustainability.

Photocatalytic Degradation of Polycyclic Aromatic Hydrocarbons in Fine Particulate Matter (PM2.5) Collected on TiO2-Supporting Quartz Fibre Filters

Airborne fine particulate matter (PM2.5) pollution is known to have adverse effects on human health, and owing to their carcinogenic and mutagenic nature, polycyclic aromatic hydrocarbons (PAHs) are of particular concern. This study investigated the effect of ultraviolet (UV)-induced photocatalysis on the degradation of PAHs in PM2.5, employing titanium dioxide (TiO2)-supporting quartz fibre filters. A TiO2 layer was formed on the quartz fibre filters, and airborne PM2.5 was collected using an air sample at a flow rate of 500 L/min for 24 h. The PM2.5 samples were subsequently irradiated with ultraviolet rays at 1.1 mW/cm2. The amounts of nine targeted PAHs (phenanthrene, PHE; anthracene, ANT; pyrene, PYR; benzo[a]anthracene, BaA; chrysene, CHR; benzo[b]fluoranthene, BbF; benzo[k]fluoranthene, BkF; benzo[a]pyrene, BaP; and benzo[g,h,i]perylene, BgP) gradually decreased during the treatment, with half-lives ranging from 18 h (PHE) to 3 h (BaP), and a significantly greater reduction was found in comparison with the PAHs collected in the control (non-TiO2 coated) quartz fibre filters. However, the degradation rates were much faster when the PAHs were in direct contact with the TiO2 layer. As PM2.5 is a mixture of various kinds of solids, co-existing components can be a rate-determining factor in the UV-induced degradation of PAHs. This was demonstrated by a remarkable increase in degradation rates following the removal of co-existing salts from the PM2.5 using water treatment.

Magnetic hydrophobic solids prepared from Pickering emulsions for the extraction of polycyclic aromatic hydrocarbons from chamomile tea

Two types of magnetic hydrophobic solids were prepared by Pickering emulsion photopolymerization using polystyrene-modified magnetic nanoparticles (PS-MNPs) as emulsion stabilizers. Additionally, PS-MNPs provided magnetic character to the final solids. W/O Pickering emulsions were produced with high amounts of oily phase (above 50 wt%), while O/W Pickering emulsions were formed with higher amounts of aqueous phase (above 60 wt%). These two types of emulsions led to two kind of solids with very different structures despite being formed by the same components. In this way, W/O Pickering emulsions produced monolithic solids, while O/W Pickering emulsions formed magnetic microparticles. Multi-walled carbon nanotubes (MWCNTs) were also added to the emulsions to provide higher hydrophobic character to the final solids. The structure and morphology of both magnetic solids containing the MWCNTs was characterized by scanning electron microscopy (SEM). Finally, their extraction efficiency was evaluated using polycyclic aromatic hydrocarbons (PAHs) as target analytes, both qualitatively (visually by the fluorescence emitted before and after the extraction) and quantitatively (using gas chromatography coupled to mass spectrometry). Therefore, the LODs ranged from 1 to 4 μg L−1 and the LOQs were between 3 and 12 μg L−1. The reproducibility of the extraction procedure with different batches of emulsions was acceptable with RSD values <13%. Finally, a recovery study was carried out in complex matrices such as chamomile tea, obtaining excellent recovery values which ranged from 99 to 108%.

Detachment dynamics of colloidal spheres with adhesive interactions.

Escape of colloidal-size particles from various kinds of solids, such as aggregates and surfaces, occurs in a wide variety of settings of both fundamental and applied scientific interest. In this paper an exact solution for the detachment of adhesive spheres from each other by means of diffusion is presented. The solution takes into account repeated detachment and reattachment events in the course of time on the way toward the permanently separated state. For strongly adhesive spheres this state is approached in an exponential manner essentially regardless of how the bound state is specified. The analytical solution is shown to capture semiquantitatively the escape from more realistic potential wells using a mapping procedure whereby equality of second virial coefficients is imposed.

A unified particle system framework for multi-phase, multi-material visual simulations

We introduce a unified particle framework which integrates the phase-field method with multi-material simulation to allow modeling of both liquids and solids, as well as phase transitions between them. A simple elasto-plastic model is used to capture the behavior of various kinds of solids, including deformable bodies, granular materials, and cohesive soils. States of matter or phases , particularly liquids and solids, are modeled using the non-conservative Allen-Cahn equation. In contrast, materials---made of different substances---are advected by the conservative Cahn-Hilliard equation. The distributions of phases and materials are represented by a phase variable and a concentration variable, respectively, allowing us to represent commonly observed fluid-solid interactions. Our multi-phase, multi-material system is governed by a unified Helmholtz free energy density. This framework provides the first method in computer graphics capable of modeling a continuous interface between phases. It is versatile and can be readily used in many scenarios that are challenging to simulate. Examples are provided to demonstrate the capabilities and effectiveness of this approach.

Components and parameters of solid/surfactant layer surface tension

Measurements of the contact angle for water, formamide and diiodomethane on the layers of R-95 Rhamnolipid, surfactin, n-octyl-β-d-glucopyranoside, n-dodecyl-β-d-glucopyranoside, n-dodecyl-β-d-maltoside, sucrose monodecanoate, sucrose monododecanoate, Tween 20, Tween 60 and Tween 80 as well as rhamnose, sucrose and poly(ethylene glycol) 8000 deposited on polytetrafluoroethylene, polyethylene, polymethyl methacrylate, polyamide and quartz were made. On the basis of the obtained results the changes of surface properties of the studied solids under the influence of the surfactants as well as rhamnose, sucrose and poly(ethylene glycol) 8000 layer were considered using different theoretical methods From these considerations it was deduced that hydrophilic and hydrophobic balance of a given solid surface covered by the surfactant layer changes as a function of the layer thickness and kind of surfactant. However, surface properties of the thick layer of a given surfactant does not depend on the kind of solids. These properties for biosurfactants are comparable to that of rhamnosa, sugar surfactants to sucrose and Tween’s to poly(ethylene glycol) 8000.

Hydrodynamics of a Liquid–Solid Circulating Fluidized Bed: Effect of Solid Feed Pipe Diameter

An experiment was conducted to acquire a set of systematic data on the solids circulation rate and solids holdup in the riser of liquid–solid circulating fluidized bed (lsCFB) to study the effect of solids feed pipe diameter. In the experiment, five kinds of solids feed pipes with inner diameter 9, 12, 22, 25 and 30 mm were provided. The result indicates that onset transitional liquid velocity, onset solids holdup, average solids holdup and solids circulation increase with increase in solids feed pipe diameter. The results substantiate that the solids feed pipe diameter plays an important role on the hydrodynamics of lsCFB in addition to operating liquid velocities (primary and auxiliary), size and density of solids, solids inventory and liquid viscosity. Based on the experimental data, correlations were proposed for predicting the maximum solids circulation rate, solids circulation rate and solids holdup, which could reproduce almost all experimental data with an accuracy of ±8%, ±13% and ±8%, respectively.

La formación de precipitados bajo el efecto de la acidez en el método de Mohr

The main goal of this study was to demonstrate the importance of acidity on precipitation process of Ag2CrO4 and Ag2O, which can be formed in Mohr's method. This can be explained through the interpretation of a Predominance-Existence Diagram, which shows reliable results of a didactic experiment. The first part of this study consists of identifying two kinds of solids, Ag2CrO4, which is reddish, and Ag2O brownish. The second part shows that acidity affects in speciation of Cr (VI) by changes in the color of the aqueous solution. Finally, it has been demonstrated that pH affects on absence or formation of certain solids. These changes can be explained by a predominance-existence diagram, which is useful to identify a logarithmic curve related with conditional solubility of Ag2CrO4 or Ag2O, the conditional solubility constant, and also concentration of silver at saturation. The finding of minimum solubility — without Ag2O can be formed-justifies that optimal interval pH to titrate on Mohr's method is 7.0 <pH< 10.

Comparative study of the texture and structure of aerogel and xerogel sulphated zirconia doped with nickel

Aerogels and xerogels based on sulphated zirconia doped with nickel in the same atomic ratios S/Zr = 0.5 and Ni/Zr = 0.1 have been synthesized by sol–gel method using two drying ways of the solvent in solid preparation steps. Aerogels obtained by drying in supercritical conditions of solvent stabilize zirconia tetragonal phase even at high calcination temperatures and present a developed surface area, whereas xerogels obtained by ordinary solvent drying in an oven are amorphous. TPR and XPS studies revealed that Ni seems to exist in different species in the two kinds of solids and it is more reducible in aerogels.

The basicity of mixed oxides and the influence of alkaline metals: The case of transesterification reactions

Several M(II)/M(III) mixed oxides were prepared and tested in two different transesterification reactions, biodiesel production from sunflower oil and methanol, and the more demanding transesterification of methyl palmitate with isobutanol. The presence of residual alkaline ions after crystallization is the main source for the strong basicity in this kind of solids, as it happened with Mg/Al mixed oxides. The effect of these alkaline traces is more evident with the most demanding reaction, in which the alkaline-free solids did not show any catalytic activity. These results seem to indicate that the strong basicity in mixed oxides is always connected to the presence of alkaline metals, irrespective from the nature of M(II) and M(III).

The filtration characteristics of hollow fiber microfiltration — Effect of various kinds of solids in the excess activated sludge

The submerged membrane separation activated sludge process has some benefits such as small installation area and good quality of treated water (effluent) etc. We made constant pressure filtration of the excess activated sludge using the microfiltration hollow fiber (pore diameter size: 0.1 μm). Solids in the activated sludge are consisted of two elements, suspended solids (SS) and dissolved solids (DS), and we define DS as the solids contained in the filtrate from glass fiber filter (pore diameter size: 0.6 μm),inthispaper.Three sludge samples were used in this work; “Activated sludge,” “Supernatant by 1600 g centrifugal settling,” and “Filtrate with glass fiber filter.” Thereby, we could widely examine the effect of various kinds of solids in the activated sludge on the filtration characteristics of this hollow fiber microfiltration. As a result, the followings were obtained. The filtration characteristics of the three samples are very different from each other, affected differently by various kinds of s...

Solid Pyrolysis Modelling by a Lagrangian and Dimensionless Approach--Application to Cellulose Fast Pyrolysis

Many kinds of solids (e.g., biomass, thermoplastic and coal) thermally decompose according to similar types of kinetic pathways. They usually include a first step giving rise to more or less stable solid or liquid species followed by competitive reactions with formation of the final products (solids, vapours, and/or gases). In order to be extended to several types of solids, the present pyrolysis model relies on an original dimensionless Lagrangian approach. Mathematical equations of mass and heat balances are written in the assumptions that non-volatiles products form distinct layers which are separated by each other by moving interfaces that propagate towards the inner parts of the sample. The conditions required to apply this Lagrangian approach to solid thermal decomposition are discussed. The time evolution of pyrolysis products and sample internal temperature profiles are obtained by numerical solving of equations written in a reduced form. The first results of simulations performed in a large range of dimensionless parameters values (thermal Thiele, Biot and thermicity criteria) are reported. It is pointed out that variations of reduced masses as a function of reduced time significantly depend on operating conditions (particularly thermal Thiele and Biot numbers). The results of the model are finally compared to experimental data reported in the literature for cellulose fast pyrolysis. The agreement is quite good considering the uncertainties with which the physicochemical parameters are known from the literature.

Use of Pressure Fluctuations to Determine Online the Regime of Gas−Solids Suspensions from Incipient Fluidization to Transport

A novel quantity, based on the concept of symmetry of the sampled pressure fluctuating signal, is developed and incorporated into our extended fluctuation model of fluidized gas−solid suspensions. The new measure of the signal symmetry makes it possible to define the transition from the final bubbling regime to the onset of turbulence in the bed. Experimental measurements were performed in a transparent glass, 6-m-tall column with an inner diameter (i.d.) of 0.08 m. Three different kinds of solids were employed in the experiments: ceramsite (particle size 1.0−1.25 mm; group D particles; spoutable particles), glass beads (particle size 0.8−1.00 mm; group D particles), and high-calcium, coarse-grained limestone (particle size 0.50−0.65 mm; group B powder; sandlike particles). It was discovered that also the different bubbling regimes and the starting point of dilute (entrainment) regimes can be identified with the aid of the proposed method. The development of the diluted beds is considerably influenced by the architecture and configuration of the top of the fluidization column.

CFD simulation of fluidization quality in the three-dimensional fluidized bed

Multiphase computational fluid dynamics (CFD) has become an alternative method to experimental investigation for predicting the fluid dynamics in gas–solid fluidized beds. The model of Brandani and Zhang, which contains additional terms in both the gas- and solid-phase momentum equations, is employed to explore homogeneous fluidization of Geldart type A particles and bubbling fluidization of Geldart type B particles in three-dimensional gas-fluidized beds. In this model, only a correlation for drag force is necessary to close the governing equations. Two kinds of solids, i.e., fine alumina powder ( d p = 60 μm and ρ p = 1500 kg/m 3) and sand ( d p = 610 μm and ρ p = 2500 kg/m 3), are numerically simulated in a rectangular duct of 0.2 m (long) × 0.2 m (wide) × 0.5 m (high) size. The results show good agreement with the classic theory of Geldart.

Characteristics Detachment of Adhered Solid to Cooling Surface for Formation of Clathrate Hydrate Slurry (Effect of Concentration of TBAB Solutions)

In air-conditioning systems, it is desirable that the liquid-solid phase change temperature of a cool energy storage material is approximately 10°C from the perspective of improving coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra-n-butylammonium Bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of concentration of TBAB solutions on the scraping force for detachment of adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally. The TBAB hydrate solids were categorized broadly into two kinds of solids. The scraping force of the TBAB hydrate solid on the heat transfer surface was different for the two kinds of the TBAB hydrate solids. The scraping force increased with the increase in the concentration of solution. It was confirmed that the concentration of solution had an effect on the scraping force required for removal of the solid.

An effect of scraper shapes on detachment of solid adhered to cooling surface for formation of clathrate hydrate slurry

AbstractIn air‐conditioning systems, it is desirable that the liquid– solid phase change temperature of a cool energy storage material is approximately 10°C from the perspective of improving the coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra‐n‐butylammonium bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of the scraper shapes on the scraping force for detachment of the adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally. The TBAB hydrate solids were categorized broadly into two kinds of solids. The scraping force of the TBAB hydrate solid on the heat transfer surface was different for the two kinds of the TBAB hydrate solids. And the scraping force of the TBAB hydrate solid formed after scraping was improved by the modifying the scraper shape. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(8): 489– 500, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20179

Measurement of Selected Thermophysical Properties of the NPL Certified Reference Material Stainless Steel 310

Flash methods have become one of the most commonly used techniques for measuring the thermal diffusivity and thermal conductivity of various kinds of solids and liquids such as metals, carbon materials, ceramics, and polymers. Easy sample preparation, small sample dimensions, fast measurement times, and high accuracy are only some of the advantages of this non-destructive measurement technique. However, the accuracy of measurement and level of uncertainty of the resulting data are becoming increasingly important for countless industrial applications. Instruments must be checked to determine the uncertainty of the system at different temperature and application ranges. One way of checking the accuracy of the results is to cross-check the unit with certified reference materials. However, there is a lack of standard materials for thermal diffusivity/thermal conductivity all over the world. Furthermore, for some available standards, the thermophysical properties are known only over a limited temperature range. Presented in this work are thermophysical property measurements on a certified thermal conductivity standard, Stainless Steel 310. Tests were carried out between −125 and 1000°C.

An Effect of Scraper Shapes on Detachment of Solid Adhered to Cooling Surface for Formation of Clathrate Hydrate Slurry

In air-conditioning systems, it is desirable that the liquid-solid phase change temperature of a cool energy storage material is approximately 10°C from the perspective of improving coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra-n-butylammonium Bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of the scraper shapes on the scraping force for detachment of adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally. The TBAB hydrate solids were categorized broadly into two kinds of solids. The scraping force of the TBAB hydrate solid on the heat transfer surface was different for the two kinds of the TABA hydrate solids. And the scraping force of the TBAB hydrate solid formed after scraping was improved by the modifying the scraper shape.

Raman spectroscopic verification of fac-Sc(PMBP)3 by solid and solute spectra and density functional method calculation

Two kinds of solids were obtained for Sc(PMBP)3 by precipitation from different solvents. They were light-yellow crystal and yellowish-white powder, and their melting points were 209 and 217°C, respectively. Raman spectra of six anhydrous samples prepared from these materials were measured and classified into two types of spectral patterns. Raman solute spectra of these two materials were measured in a dilute solution of dichloromethane, in which the solute is a free molecule in a solvent cage. Their spectra were considerably similar to each other, but they indicated clear differences in some pairs of bands. One of these two molecules was concluded to be a facial form of Sc(PMBP)3, because the other constituent has been established to be a meridional form of Sc(PMBP)3 by X-ray analysis of a single crystal. Structural optimization for mer- and fac-Sc(PMBP)3 and their vibrational calculation of frequencies and intensities were carried out with the density functional method of B3LYP/6-31G**. Their computed Raman spectra were well coincident with their observed spectra. The existence of fac-Sc(PMBP)3 has been established by thermal analysis, Raman spectroscopy and ab initio calculation.