Dynamics adsorption of the enhanced CH4 recovery by CO2 injection

The dynamic adsorption isotherms of CO₂-EGR were measured by using an Intelligent Gravimetric Analysis system. In the initial CO₂ injecting stage, all the injected CO₂ enters into the adsorbent and the mole fraction of CH₄ in the gas phase () is maintained at 1.0. The CH₄ recovery factor () increases. The duration of this stage (t_CD) depends on the selectivity of CO₂ over CH₄ (). An adsorbent with large has long t_CD. In the second stage, the injected CO₂ competes with CH₄ for adsorption. The cumulative of the second stage is much larger than that of the initial stage. However, decreases sharply. in the whole CO₂ injection is always larger than that before CO₂ injection, suggesting that CH₄ desorption results from the displacement of CO₂ rather than from pressure depletion.     

The axial dispersion of liquid solutions and solid suspensions in planar oscillatory flow crystallizers

The planar oscillatory flow crystallizer (planar-OFC) was designed with a rectangular cross-section to improve the flow and suspension of solids of conventional OFCs. Residence time distribution experiments with liquid and solid tracers were performed to assess the effect of the net flow rate, Q , the frequency, f , and the amplitude of oscillation, x₀ , on the axial dispersion of liquids, , and solids, , in three planar-OFCs with different geometries. It was found that Q and f have in general positive effects on and , and x₀ has negative effects. Furthermore, identical values of and were obtained in each crystallizer. It was also found that the interaction between Q and x₀ is the most significant one in all systems. These results show that the three crystallizers have similar axial dispersion performances with liquids and solids. This is of paramount importance for multiphase systems such as crystallization.     

Flexible distillation test rig on a laboratory scale for characterization of additively manufactured packings

Additive manufacturing is increasingly being used to develop innovative packings for absorption and desorption columns. Since distillation has not been in focus so far, this article aims to fill this gap. The objective is to obtain a miniaturized three dimensional (3D) printed packed column with optimized properties in terms of scalability and reproducibility, which increases process development efficiency. For this purpose, a flexible laboratory scale test rig is presented combining standard laboratory equipment with 3D printed components such as innovative multifunctional trays or the column wall with packing. The test rig offers a particularly wide operating range for column diameters between and . First results regarding the time to reach steady-state, operational stability, and separation efficiency measurements are presented using a 3D printable version of the Rombopak 9M. Currently, further developed and newly designed packing structures are being characterized, which should exhibit optimized properties especially with respect to scalability and separation efficiency.     

Extension of the validation method for vapor–liquid equilibrium data to systems with nonvolatile components

In this work, a method is proposed to validate the experimental data of solutions of n-components in vapor–liquid equilibria (VLE) with some nonvolatile component (nv-VLE). The methodology is based on the resolution of the differential Gibbs–Duhem equation using two forms (differential and integral) described in a previous work. The combination of both forms evaluates as many relationships between the variables that define each data series in equilibrium (p, T, x_{1, … , n-1}, y_{1, … , n-1} ) as degrees of freedom the problem has, although in this work it is only necessary to use the integral form. The proposed method is applied to 70 experimental data series published in the literature, considering the numerical limits previously assigned to parameters established for the integral-form, according to the following. (a) A parameter ψ is identified as p or T according to if the data are iso-T or iso-p; (b) verification of the data is assessed by the difference , with > 0, and is determined by an uncertainty procedure of the inconsistency function , being ; and (c) The parameter κ_ψ depends on the type of equilibrium. With κ_ψ = 5, the rejection ratio of the total analyzed is 12%, this percentage increases as the level of quality required increases above 31% for κ_ψ = 3. The calculations require a precise representation of the binomial {data+model}, which produces excellent results for the treatment of nv-VLE and the properties of solutions, whose parametrization is achieved by an advanced procedure of combined optimization.     

Frequency dependence of antiferroelectricferroelectric phase transition of PLZST ceramic

Antiferroelectric (AFE) ceramics are promising for applications in high-power density capacitors, transducers, etc. The forward switching field and backward switching field are critical performance indicators for AFE ceramics, and the coupling between the structure transition and domain orientation makes them different from the coercive field of ferroelectric (FE). Moreover, in practical applications, AFE ceramics are often required to operate at varying frequencies. However, systematic studies regarding the frequency dependence of and are insufficient. In this work, (PLZST) AFE ceramic was fabricated, and two empirical formulas (, ) were proposed to predict the frequency dependence of and . The formulas are based on the electric field–induced phase transition characteristics of AFE and the Kolmogorov–Avrami–Ishibashi domain nucleation-switching model. Furthermore, the dynamic hysteresis loops of PLZST at various frequencies (1–1000 Hz) and temperatures (–) were investigated. The results show that the electric field–induced phase transition of AFE ceramic is dominated by the coupling between the structural transition and domain orientation. The domain orientation hinders the structure transition, leading to an increase in and a decrease in as the frequency of applied electric field increases. Meanwhile, the domain growth process is affected by the structure of AFE, and the value of (domain growth dimensionality) increases with the stability of the AFE structure. For comparison, (PLBZST) relaxor FE ceramic was fabricated. Due to the high mobility of the microdomain, the dynamic hysteresis loop of PLBZST ceramic exhibits excellent frequency stability. The charge–discharge experiment with an ultrahigh equivalent frequency (100 kHz) was performed to investigate the frequency stability of energy release of PLZST and PLBZST. The results may provide guidance for research pertaining to ceramic capacitors with high-power density and high-frequency stability.     

On the Use of Side-Chain NMR Relaxation Data to Derive Structural and Dynamical Information on Proteins: A Case Study Using Hen Lysozyme

Values of and order parameters derived from NMR relaxation measurements on proteins cannot be used straightforwardly to determine protein structure because they cannot be related to a single protein structure, but are defined in terms of an average over a conformational ensemble. Molecular dynamics simulation can generate a conformational ensemble and thus can be used to restrain and order parameters towards experimentally derived target values (exp) and (exp). Application of and order-parameter restraining MD simulation to bond vectors in 63 side chains of the protein hen egg white lysozyme using 51 (exp) target values and 28 (exp) target values shows that a conformational ensemble compatible with the experimentally derived data can be obtained by using this technique. It is observed that order-parameter restraining of C−H bonds in methyl groups is less reliable than order-parameter restraining because of the possibly less valid assumptions and approximations used to derive experimental (exp) values from NMR relaxation measurements and the necessity to adopt the assumption of uniform rotational motion of methyl C−H bonds around their symmetry axis and of the independence of these motions from each other. The restrained simulations demonstrate that side chains on the protein surface are highly dynamic. Any hydrogen bonds they form and that appear in any of four different crystal structures, are fluctuating with short lifetimes in solution.     

Modeling of the volatile organic compounds biodegradation process in the trickle-bed bioreactor—Analysis of the model parametric sensitivity

Mathematical models of the process of air purification from hydrophobic (styrene) or hydrophilic (vinyl acetate, VA) compounds carried out in a co-current trickle-bed bioreactor were presented. These models were marked as TSM (two-substrate model), OSM (one-substrate model) and AOSM (approximate one-substrate model). The experimental database was exploited to validate the TSM which approximated very well the experimental data; the mean percentage error of RE prediction did not exceed 3% for styrene and 4.1% for VA. For the tested systems, TSM was only sensitive to the changes in biomass dry density X_b and effective diffusion coefficient D_j,ef values. The percentage relative error of the state variable computed using OSM/AOSM in relation to the value obtained from TSM was the quantitative criterion for comparison of the results obtained using different mathematical models of the process. It was shown that the simplified models describe the process investigated with satisfactory accuracy.     

Thermoelectric properties and phase transition of doped single crystals and polycrystals of Bi2Te3

The temperature dependences of the electrical conductivity , Seebeck coefficient , and heat capacity C_p(T) of polycrystalline samples of Bi₂Te₃, Bi₂Te₃+1%CuI, and Bi₂Te₃+1%(CuI+1/2Pb) are investigated in the temperature range below room temperature. Based on the temperature dependences of all investigated physical properties, it is discovered that phase transition occurs at 120–200 K. Investigation of single crystals shows that anomalies in the electrical resistivity occur only across the crystal growth axis (across the well-conducting Bi–Te plane). Investigation of the low-temperature dependence of electrical conductivity shows that all polycrystalline samples exhibit quasi-two-dimensional electron transport. Additionally, quasi-two-dimensional transport is detected in single crystals based on anisotropy analysis (where is the resistivity along the crystal growth axis, and is resistivity across the crystal growth axis) and temperature dependence below 50 K. The Fermi energy is estimated using the temperature dependence of . It is discovered that an increase in at T > 200 K is associated with the phase transition. For single-crystal samples, the maximum thermoelectric figure of merit ZT, as observed along the crystal growth axis, increases with doping. A maximum ZT value of ∼1.1 is observed for the Bi₂Te₃+1%(CuI+1/2Pb) sample at room temperature ().     

Investigation of the effect of surface phosphate ester dispersant on viscosity by coarse-grain modeling of BaTiO slurry

To understand the role of phosphate ester dispersant, we investigated the rheology of a BaTiO slurry. For the model case, a coarse-grain molecular dynamics (CGMD) simulation was performed with the butyral polymer didodecyl hydrogen phosphate (DHP) in the toluene/ethanol solvent. By systematically analyzing the effect of DHP from an atomic-scale first principle and from all-atom MD to microscale CGMD simulation, we investigated how the adsorption of a DHP dispersant on a BaTiO surface affects the microstructure rheology of a BaTiO slurry. The first-principle and all-atom MD simulation suggests that DHP molecules prefer to locate near the BaTiO surface. CGMD simulation shows a reduction in viscosity with an increase in dispersants, suggesting that the dispersant population near the BaTiO surface plays a key role in controlling the rheology of the BaTiO slurry. In this study, we propose an approach for understanding the BaTiO slurry with molecular-level simulations, which would be a useful tool for efficient optimization of slurry preparation.     

Diffusion of ellipsoidal granular particles in shear flow

The diffusion of nonspherical particles has not been well understood due to the complexity of their contact mechanics and self-organization of their orientations. We perform discrete element method simulations of monodisperse ellipsoids in a shear flow with Lees-Edwards boundary conditions to quantify the relation between the diffusion coefficient and the flow parameters. The results indicate that the particle aspect ratio strongly affects the diffusion coefficient by influencing the particle orientation and alignment. We develop a scaling law for the diffusion coefficient perpendicular to the flow direction, D_yy, which combines the influences of the shear rate , the solids fraction f, the effective particle diameter d_eff and the particle aspect ratio Z. We show that , where k_d is a dimensionless pre-factor, and a fit is obtained for the functional form of χ(f, Z). This scaling law will be useful in developing continuum transport models for applications.     

Influence of water activity on belite (β-C2S) hydration

The hydration of the two most reactive phases of ordinary Portland cement (OPC), tricalcium silicate (C₃S), and tricalcium aluminate (C₃A) is successfully halted when the activity of water () falls below critical thresholds of 0.70 and 0.45, respectively. It has been established that the reduction in relative humidity (RH) and  suppresses the hydration of all anhydrous phases in OPC, including less explored phases like dicalcium silicate, that is, belite (β-C₂S). However, the degree of suppression, that is, the critical threshold, for β-C₂S, standalone has yet to be established. This study utilizes isothermal microcalorimetry and X-ray diffraction techniques to elucidate the influence of on the hydration of -C₂S suspensions via incremental replacements of water with isopropanol (IPA). Experimentally, this study shows that with increasing IPA replacements, hydration is increasingly suppressed until eventually brought to a halt at a critical threshold of approximately 27.7% IPA on a weight basis (wt.%_IPA). From thermodynamic estimations, the exact critical threshold and solubility product constant of -C₂S () are established as 0.913 and 10^−12.68, respectively. This study enables enhanced understanding of β-C₂S reactivity and provides thermodynamic parameters during the hydration of β-C₂S-containing cementitious systems such as OPC-based and calcium aluminate-based systems.     

Synchrotron x-ray spectroscopy investigation of the Ca1−xLnxZrTi2−x(Al,Fe)xO7 zirconolite ceramics (Ln = La,Nd, Gd,Ho, Yb)

When incorporating actinides into zirconolite for high-level radioactive waste immobilization, Al³⁺ and Fe³⁺ ions generally act as charge compensators. In this study, we rationally designed a series of (Ln = La, Nd, Gd, Ho, Yb) to unravel the dopant solubility and evolutions of the crystalline phase and local environment of cations through synchrotron X-ray methods. It was found that single zirconolite phase is difficult to obtain and the fraction of perovskite have an increase with x from 0.1 to 0.9 in . Formation of both zirconolite-2M and zirconolite-3O phases was observed in and . Phase transformation from zirconolite-2M to 3O occurs at x = 0.7 for while x = 0.9 for . The solubility of and to form single zirconolite-2M can reach to 0.9 f.u. and 0.7 f.u., respectively. The evolution of lattice parameters of zirconolite in is greatly related to the ionic radii of cations and substitution mechanism among the cations. X-ray absorption near edge spectroscopy revealed that Fe³⁺ ions replace both five- and six-coordinated Ti sites and the ratio of TiO₅ to TiO₆ decreases when increasing dopant concentration in the . For the local environment of Zr⁴⁺, the major form is ZrO₇ with a trace of ZrO₈.     

Ultralow dielectric loss in Y-doped SrTiO3 colossal permittivity ceramics via designing defect chemistry

Effects of doping of Y and sintering atmosphere on the dielectric properties of Sr_1-1.5xY_xTiO₃ ceramics (SYT, x = 0-0.014) were systematically investigated. The SYT14 (x = 0.014) ceramic sintered in N₂ attains a colossal permittivity (CP, Ɛ_r = 28 084@ 1kHz, 27 685@ 2MHz) and an ultralow dielectric loss (tanδ = 0.007@ 1kHz, 0.003@ 2MHz) at room temperature. Because of using of the A-site deficient, there are in SYT ceramics. Through the comprehensive analysis of dielectric responses, X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and complex impedance data, it is proved that doping of Y promotes the formation of (Y³⁺ are located at Sr²⁺ site), (Y³⁺ are located at Ti⁴⁺ site), and Ti³⁺, and sintering in reducing atmosphere of N₂ results in more (oxygen vacancy) and (strontium vacancy) generating in SYT ceramics. The defect dipoles, , , , , , and formed by introduced defects make charge carriers localized in SYT ceramics. The combined action of the massive defect dipoles is responsible for the ultralow tanδ and CP in SYT14 ceramics sintered in N₂.     

Application of fracture mechanics for the characterization of poly(vinyl chloride) pipes. II. Evaluation of a ring-type specimen for fracture mechanics testing

An unplasticized poly(vinyl chloride) (U-PVC) pipe sample used in infrastructure applications in Brazil (nominal diameter DN 100, outside diameter 110 mm) was evaluated according to different fracture mechanics methodologies, including essential work of fracture (EWF) and other fracture toughness parameters such as the stress intensity factor and plane strain energy release rate . This pipe sample was also tested for the quality of processing (degree of gelation) via differential scanning calorimetry (DSC) and tensile strength. The comparative evaluation of different specimen configurations—curved specimens in three-point bending (CTPB) and full rings in tension (SNRT), in thicknesses varying from 5 to 30 mm, showed initial evidence of the suitability of ring-type specimens for the evaluation of EWF and . Results also indicate that the full ring geometry, at least in the present experimental setup, presents some drawbacks probably due to the storage of large amounts of elastic energy throughout the test. This fact leads to relevant deviations in both load–displacement behavior and results for strain energy release rate (), and the results found here will guide future research using full and split rings in different loading modes and improved experimental setups. It was also confirmed that the value of , determined by a modified Charpy test, is independent of the type of specimen tested, as long as the test mode and specimen width are the same. Both the experimental value of and the estimated value for the plane strain stress intensity factor () showed excellent agreement with values reported for other U-PVC compositions.     

Design of a defect-induced orange persistent luminescence phosphor BaZnGeO4:Bi3+

We report a novel bright orange persistent luminescence (PersL) phosphor BaZnGeO₄:Bi³⁺ with broad emission and PersL spectra. Its crystal structure, photoluminescence (PL) spectra, thermoluminescence (TL) spectra and PersL spectra were investigated in detail. The two emission bands at 440 nm and 595 nm originate from Bi³⁺ ions in normal Ba²⁺ sites (Bi1) and Ba²⁺ sites close to vacancy defects (Bi2), respectively. The introduction of and defects improves the emission intensity of Bi2 more than that of Bi1, demonstrating that Bi2 is related to the vacancy defects. The orange emission and PersL properties of BZGO:Bi³⁺ can be improved when a little and defects are introduced, because the introduction of and defects makes it easier for Bi³⁺ to enter in Ba²⁺ sites; and for PersL, and defects can perform as the effective trap centers to capture more charges, which is beneficial for PersL. BZGO:Bi³⁺ has quite good thermal stability, and the bright orange PersL can be observed by the naked eye for 1 h. Finally, a feasible PersL mechanism of BZGO:Bi³⁺ was proposed to clarify the PersL-generation process.     

Poling tuning: A plausible solution for minimizing microphony and secondary pyroelectric coefficient in ferroelectrics

This study proposes the idea of reducing the microphony effect and secondary pyroelectric coefficient in pyroelectric detectors by tuning the poling orientation. Mathematically, it has been shown that piezoelectric strain coefficients get altered by changing the poling direction. Eventually, for a couple of materials it has been demonstrated that microphony and secondary pyroelectric coefficient can be diminished by poling them at a given orientation. The poling angle nullifying secondary pyroelectric coefficient was found to be 58.2°, 47.1°, and 78.9° for (PZN-0.08PT), (PMN-PT), and (BCT-0.48BZT) respectively while no such value existed for (PZT-5A).     

Fabrication and characterization of tetragonal yttria-stabilized zirconia single-crystalline thin film

Tetragonal yttria-stabilized zirconia thin film was successfully fabricated by a pulsed laser deposition method. The thin film grew heteroepitaxially with the orientation relationship of ZrO₂‖Al₂O₃. Energy dispersive X-ray spectroscopy mapping revealed that Y³⁺ ions were distributed homogeneously without local segregations. X-ray and electron-diffraction analysis confirmed a single crystalline structural feature of the film. On the other hand, high-resolution scanning transmission electron microscopy observations show that this film contains small-angle tilt grain boundaries, which is composed of the periodic array of dislocations with the Burgers vector .     

Role of oxygen-vacancy in piezoelectric properties and fatigue behavior of (Bi0.5Na0.5)0.93Ba0.07Ti1+xO3 ceramics

In this reported study, (Bi_0.5Na_0.5)_0.93Ba_0.07Ti_1+xO₃ (abbreviated as BNBT_1+x) ceramics, containing Ti-nonstoichiometry that ranged from a 2% deficiency to a 1% excess, were designed and systematically characterized. The results of the X-ray diffraction Rietveld refinement and X-ray photoelectron spectroscopy analysis of these materials revealed that the amount of Ti in the BNBT_1+x ceramics significantly affected the degree of coexistent rhombohedral/tetragonal phases and also affected the content of singly/doubly charged oxygen-vacancy (/) in the ceramics. After poling and 10⁵ fatigue cycles, the variation in Raman resonance line-width of the Ti–O bond in the BNBT_1+x ceramics was found to be strongly dependent on the amount of Ti in the ceramic. The → transformation and clustering of the defects under electrical loading were considered to be a critical factor in electric field-induced structural transition and fatigue properties of the material.     

Regeneration and utilization of waste phenolic formaldehyde resin: A performance investigation

Recycled thermosetting phenolic formaldehyde (RPF) resins were pulverized to micron-sized powders and successfully reused as an effective component by reactive-injecting with neat phenolic formaldehyde (PF) and/or trioxymethylene (TOX) to prepare regenerated phenolic formaldehyde (i.e., and ). Tensile strength (σ_f), impact strength (I_s), and density (ρ) of and specimens were reduced as RPF concentrations or average particle sizes increased. It is worth emphasizing that σ_f, I_s, and ρ of each reaction-injected series having a fixed RPF concentration and average particle size improved to a maximum value, as TOX concentrations reached a corresponding optimal value. This is the first investigation to report that σ_f and I_s of proper regenerated PF/RPF/TOX specimens using ≦20 wt % RPF waste were ≥ 95% of those of the virgin reaction-injected PF. Possible reasons accounting for these improved mechanical properties were proposed based on results from their Fourier transform infrared analysis (FTIR). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47445.     

Estimation of the critical properties of compounds using volume-based thermodynamics

The importance, yet scarcity of the critical constants of thermally unstable fluids warrants the development of reliable methods for the estimation of these essential thermodynamic properties. A thorough investigation undertaken in this study on 1,589 compounds belonging to 83 chemical classes, indicated that the ratio of critical temperature to critical pressure of both low and high molecular weight compounds could be well expressed in terms of their volumetric properties. In addition, two new methodologies are presented for estimating V_c, as well as an indirect approach for prediction of T_c from surface tension data, altogether allowing the calculation of Z_c. Moreover, comparative studies are made with five group contribution methods. It is also demonstrated that by employing the Peng-Robinson EOS, and without prior knowledge of the critical properties, it is possible to calculate various thermophysical properties including P^sat., T_b, , ∆H^vap. , C_p, and even the T_c and P_c themselves.