Composite Design Strategy Research Articles

Superior energy storage properties and excellent stability achieved in environment-friendly ferroelectrics via composition design strategy

Abstract With increasing demand of environmental protection and development of pulsed power technologies, environment-friendly ferroelectrics with superior energy storage properties (ESP) have attracted more and more attention in recent years. However, the recoverable energy storage density (Wrec), the energy storage efficiency (η) and the electric breakdown strength (Eb) of most environment-friendly ceramics are lower than 3 J cm−3, 80% and 300 kV cm−1, respectively. In this work, we induced the polar nano regions (PNRs) and decreased grain size to submicron scale via composition design strategy to optimize the ESP. The ultra-high Wrec (6.64 J cm−3) and η (96.5%) can be achieved simultaneously for (1-x)Bi0.5Na0.5TiO3-xSrNb0.5Al0.5O3 ((1-x)BNT-xSNA) environment-friendly ceramics with x = 0.20 at 520 kV cm−1. Obviously, the samples maintain high η (>92%) within the frequency range of 1–100 Hz and the temperature range of 30–150 °C. Therefore, the (1-x)BNT-xSNA ceramics possess superior ESP and excellent stability of ESP, which are promising candidate environment-friendly materials for pulsed power systems applications.

TiN/Ni/C ternary composites with expanded heterogeneous interfaces for efficient microwave absorption

At present, constructing composite materials with different absorbing mechanism is the popular strategy to realize the complementary and synergetic properties for electromagnetic (EM) wave absorbing materials. However, the effective magnetic response is generally struggled to achieve. Besides the composition design strategy, fully utilizing the interfacial polarization is another efficient method for the fabrication of microwave absorbing (MA) materials. In this work, the titanium nitride/nickel/carbon (TiN/Ni/C) ternary composites were fabricated through an in-situ thermal nitridation process. The EM dissipation factors can be regulated by rational design of the ternary heterogeneous interface through varying the precursor composition. The minimum reflection loss (RL) of the optimized TiN/Ni/C nanocomposite can reach −35.1 dB at 12.4 GHz and the effective absorption bandwidth (EAB) is 3.6 GHz with a thickness of 1.7 mm. The enhanced absorbing property is benefited from the effective structure design with tunable heterogeneous interface and continuous carbon matrix which would achieve promoted interfacial polarization, conductivity relaxation and the electromagnetic impedance matching. Special structures of TiN/Ni/C ternary composites played a vital role in the effective electromagnetic absorption properties, which is significant for designing efficient MA materials.

Palladium (II) anchored on a magnetic mesoporous polymelamine–formaldehyde as new catalyst for Heck coupling reaction: optimization of reaction using response surface methodology

The paper describes synthesis of a novel mesoporous and magnetically regenerated heterogeneous nanocatalyst with high catalytic activity. The synthesis strategy includes a one-step polycondensation reaction of melamine, formaldehyde and FeCl3·6H2O in a simple and sustainable manner and followed by immobilization of Pd(II) on it. Formation and properties of nanocomposite were characterized by different techniques; the results were illustrated good surface area and a well-defined mesopore structure. Also the palladium-catalyzed C–C bond formation between aryl halides and olefins was selected to survey the activity of the synthesized nanocatalyst. Central Composite Design (CCD) strategy was used to predict the optimum synthesis conditions and identify the remarkable and effective factors including temperature, period of the reaction and amount of catalyst. These results were also verified experimentally. In order to minimize systematic error, the experimental runs as a randomized fashion were accomplished.

Optimized glycerol uptake from biodiesel by activated carbon prepared of Pequi (Caryocar brasiliensis Camb.) biomass residues: A novel raw material option in Brazil

Optimized glycerol removal by activated carbon prepared with Pequi biomass residues (PBAC) was performed under the effect of different temperatures, doses of PBAC, and contact times. The experiments were arranged in a central composite design strategy following a 23 factorial configuration, totalizing 30 runs. Uptake of glycerol fluctuated between 71.3% and 96.9%, and the experimental data were better represented by a quadratic mathematical model (R2 > 0.99, p < 0.01). All independent variables and their interactions presented statistical significance (p < 0.05) on the process (temperature, p = 0.033; PBAC dosage, p < 0.0001; and contact time, p = 0.024). The interaction between increased temperatures and PBAC dosages lowered the glycerol uptake in approximately 25%. Glycerol uptake fluctuated between 85% and 87% when there was an interaction between increased temperatures and contact times. The highest glycerol uptake peak (96.9%) occurred at the lowest PBAC dosage (0.125 g), a contact time of 25 min, and a temperature of 22.5 °C. An optimized uptake of 95.6% occurred when variables mutually correlated at a temperature of 21.7 °C, a PBAC dosage of 0.29 g, and a contact time of 23.4 min. Validation experiments predicted a removal efficiency of 90.1% ± 6.64, differing in 5.5% from the optimized conditions. The values randomly predicted by the Monte Carlo simulation for glycerol removal efficiency were in close agreement with the experimental data. The lack of fit to the quadratic model was affected by the independent variables in the following magnitude order: contact time < PBAC dose < temperature.

The role of secondary phase in enhancing transduction coefficient of piezoelectric energy harvesting composites

A new composite design strategy tailors the synergistic change of d33 and εr to obtain a high d33·g33.

The design and mechanical behaviors of in-situ formed ductile dendrite Ti-based bulk metallic glass composites with tailored composition and mechanisms

Up to now, few work has concerned about the composition design strategy in the field of in-situ dendrite bulk metallic glass composites (BMGCs) for the difficulty to mediate single element in the multi-component system. In this work, an innovative composition design strategy was proposed, and a novel series of in-situ β dendrite reinforced Ti-based BMGCs were prepared. It was found that the real composition of the in-situ formed dendrites and amorphous phase is well consistent with the designed one. Accordingly, the dendrite composition is tailored monotonically and precisely, while the composition and volume fraction keep similar for the amorphous matrix in the composites. The microstructure of the dendrites and the mechanical properties and mechanisms of the overall composites are essentially controlled by the dendrite composition. According to the corresponding deformation mechanisms which transform from stress-induced martensitic transformation and mechanical twinning to dislocation slip, these alloys can be classified into two groups: the stress-induced martensitic transformation type and the none-phase transformation type. The composition design strategy proposed in this work and the correlation between the dendrite composition and the mechanical mechanisms may provide useful guidance for the development of in-situ β dendrite reinforced BMGCs with optimized mechanical properties.

A composite approach boosts transduction coefficients of piezoceramics for energy harvesting

Piezoelectric energy harvesting is a hotspot in the field of new energy, the core goal of which is to prepare piezoceramics with a high transduction coefficient (d33×g33). The traditional solid–solution design strategy usually causes the same variation trend of d33 and εr, resulting in a low d33×g33 value. In this work, a composite design strategy was proposed that uses PZN–PZT/ZnAl2O4 as an example. By introducing ZnAl2O4, which is nonferroelectric with low εr, to the PZN–PZT piezoelectric matrix, εr decreased rapidly while d33 remained relatively stable. This behavior was ascribed to the increase of Q33 caused by an interfacial effect facilitating the formation of micro-domain structure.

Combined Homogeneous Surface Diffusion Model – Design of experiments approach to optimize dye adsorption considering both equilibrium and kinetic aspects

Adsorption, a popular technique for removing azo dyes from aqueous streams, is influenced by several factors such as pH, initial dye concentration, temperature and adsorbent dosage. Any strategy that seeks to identify optimal conditions involving these factors, should take into account both kinetic and equilibrium aspects since they influence rate and extent of removal by adsorption. Hence rigorous kinetics and accurate equilibrium models are required. In this work, the experimental investigations pertaining to adsorption of acid orange 10 dye (AO10) on activated carbon were carried out using Central Composite Design (CCD) strategy. The significant factors that affected adsorption were identified to be solution temperature, solution pH, adsorbent dosage and initial solution concentration. Thermodynamic analysis showed the endothermic nature of the dye adsorption process. The kinetics of adsorption has been rigorously modeled using the Homogeneous Surface Diffusion Model (HSDM) after incorporating the non-linear Freundlich adsorption isotherm. Optimization was performed for kinetic parameters (color removal time and surface diffusion coefficient) as well as the equilibrium affected response viz. percentage removal. Finally, the optimum conditions predicted were experimentally validated.

Cloning Nacre's 3D Interlocking Skeleton in Engineering Composites to Achieve Exceptional Mechanical Properties.

Ceramic/polymer composite equipped with 3D interlocking skeleton (3D IL) is developed through a simple freeze-casting method, exhibiting exceptionally light weight, high strength, toughness, and shock resistance. Long-range crack energy dissipation enabled by 3D interlocking structure is considered as the primary reinforcing mechanism for such superior properties. The smart composite design strategy should hold a place in developing future structural engineering materials.

Solidification Microstructure, Segregation, and Shrinkage of Fe-Mn-C Twinning-Induced Plasticity Steel by Simulation and Experiment

A 3D cellular automaton finite element model with full coupling of heat, flow, and solute transfer incorporating solidification grain nucleation and growth was developed for a multicomponent system. The predicted solidification process, shrinkage porosity, macrosegregation, grain orientation, and microstructure evolution of Fe-22Mn-0.7C twinning-induced plasticity (TWIP) steel match well with the experimental observation and measurement. Based on a new solute microsegregation model using the finite difference method, the thermophysical parameters including solid fraction, thermal conductivity, density, and enthalpy were predicted and compared with the results from thermodynamics and experiment. The effects of flow and solute transfer in the liquid phase on the solidification microstructure of Fe-22Mn-0.7C TWIP steel were compared numerically. Thermal convection decreases the temperature gradient in the liquid steel, leading to the enlargement of the equiaxed zone. Solute enrichment in front of the solid/liquid interface weakens the thermal convection, resulting in a little postponement of columnar-to-equiaxed transition (CET). The CET behavior of Fe-Mn-C TWIP steel during solidification was fully described and mathematically quantized by grain morphology statistics for the first time. A new methodology to figure out the CET location by linear regression of grain mean size with least-squares arithmetic was established, by which a composition design strategy for Fe-Mn-C TWIP steel according to solidification microstructure, matrix compactness, and homogeneity was developed.

Speciation and determination of Cr(iii) and Cr(vi) by directly suspended droplet microextraction coupled with flame atomic absorption spectrometry: an application of central composite design strategy as an experimental design tool

Directly suspended droplet microextraction combined with flame atomic absorption spectrometry was successful in the speciation and pre-concentration of Cr(iii) and Cr(vi).

Revealing the factors influencing a fermentative biohydrogen production process using industrial wastewater as fermentation substrate.

BackgroundBiohydrogen production through dark fermentation using organic waste as a substrate has gained increasing attention in recent years, mostly because of the economic advantages of coupling renewable, clean energy production with biological waste treatment. An ideal approach is the use of selected microbial inocula that are able to degrade complex organic substrates with simultaneous biohydrogen generation. Unfortunately, even with a specifically designed starting inoculum, there is still a number of parameters, mostly with regard to the fermentation conditions, that need to be improved in order to achieve a viable, large-scale, and technologically feasible solution. In this study, statistics-based factorial experimental design methods were applied to investigate the impact of various biological, physical, and chemical parameters, as well as the interactions between them on the biohydrogen production rates.ResultsBy developing and applying a central composite experimental design strategy, the effects of the independent variables on biohydrogen production were determined. The initial pH value was shown to have the largest effect on the biohydrogen production process. High-throughput sequencing-based metagenomic assessments of microbial communities revealed a clear shift towards a Clostridium sp.-dominated environment, as the responses of the variables investigated were maximized towards the highest H2-producing potential. Mass spectrometry analysis suggested that the microbial consortium largely followed hydrogen-generating metabolic pathways, with the simultaneous degradation of complex organic compounds, and thus also performed a biological treatment of the beer brewing industry wastewater used as a fermentation substrate.ConclusionsTherefore, we have developed a complex optimization strategy for batch-mode biohydrogen production using a defined microbial consortium as the starting inoculum and beer brewery wastewater as the fermentation substrate. These results have the potential to bring us closer to an optimized, industrial-scale system which will serve the dual purpose of wastewater pre-treatment and concomitant biohydrogen production.

A parametric study of supercritical carbon dioxide extraction of oil from Moringa oleifera seeds using a response surface methodology

This paper reports a study of supercritical CO2 extraction of oil from Moringa oleifera seeds using a SFT Custom SCW–SFE system. The effects of pressure, temperature, flow rate of supercritical fluid and extraction time on the oil yield were investigated using a central composite experimental design strategy to determine the significant parameters and their interactions. The experimental results showed that increasing pressure, extraction time, and the CO2 flow rate significantly increased the oil yield. However, the effect of temperature on the oil yield was also found to depend on the pressure with the oil yield increasing with increasing temperature at high pressures but decreasing at low pressures. In addition, the effect of particle size on the oil yield was also investigated and it was found that the oil yield increased with the decreasing particle size, suggesting that the intraparticle diffusion played an important role. The oil extracted was characterized using a GC and NMR and compared against oil extracted using the Soxhlet extraction. Oleic acid, a high-value monounsaturated Omega-9 fatty acid, was the main components in the oils, it accounted for nearly 70% of all the fatty acids present in the oil extracted. Although the oil yield of the supercritical fluid extraction was slightly lower than that of the Soxhlet extraction, the GC and 1H NMR analysis indicated that the chemical compositions of the oils extracted by these two methods were very similar.

Study on the combined effects of essential oils on microbiological quality of Fior di Latte cheese

The effectiveness of three natural compounds in slowing down the deterioration of microbial quality of Fior di latte cheese is addressed. In particular, the control of the growth of spoilage microorganisms and the determination of the Microbiological Stability Limit (MAL) were the main goals. A Central Composite Design (CCD) strategy was adopted to highlight possible combined effects between three essential oils: sage and two types of lemon. Results showed an increase in the MAL value for all cheese samples packaged with the antimicrobial compounds, compared with the control cheese. Moreover, the combinations of the three essential oils indicated that the substances can act in a synergistic or antagonistic way, depending on their concentrations. In particular, a synergistic effect was evident when the three compounds were used at about 3000 ppm.

Atomic Layer Deposition of Quantum Confined Nanostructures on Particles

Atomic layer deposition (ALD) was used here to experimentally demonstrate the ability to deposit films that exhibit quantum confinement on spherical particle surfaces. Polycrystalline ZnO films ranging from ~1.5 to 15 nm in thickness were deposited via ALD using diethylzinc and hydrogen peroxide at 100{degree sign}C. Conformal, pinhole-free films were deposited on Si wafers and on nano-sized spherical SiO2 particles using an augmented central composite design strategy. A statistical design of experiments was performed to quantify the crystallite size of the primary peaks associated with polycrystalline ZnO, as well as the change in bandgap associated with the small crystal domains based on the number of ALD cycles and thermal annealing post-treatments. The shift in the optical bandgap of ZnO nanoshells was correlated to the domain size within the films at each point in the experimental matrix. The blue shift of 0.3 eV dissipated beyond crystallite sizes exceeding ~10nm, which was indicative of quantum confinement.

Atomic layer deposition of quantum-confined ZnO nanostructures

The modulation of optoelectronic properties, such as the bandgap of apure-component semiconductor material, is a useful ability that can beachieved by few techniques. Atomic layer deposition (ALD) was used here toexperimentally demonstrate the ability to deposit films that exhibit quantumconfinement on three-dimensional surfaces. Polycrystalline ZnO films ranging from∼1.5 to 15 nm in thickness were deposited via ALD using diethylzinc and hydrogen peroxide at100 °C. Conformal, pinhole-free films were deposited on Si wafers and on nanosized sphericalSiO2 particles using an augmented central composite design strategy. Powderx-ray diffraction was used to measure the crystallite size of the films andmonitor size evolution on the basis of the number of ALD cycles and thermalannealing post-treatments. The absorbance of the ZnO films on Si wafers andSiO2 particles was measured using spectroscopic ellipsometry and diffuse transmittancetechniques, respectively. Post-deposition annealing steps increased the crystallitesize of the films, independently of the coating thickness. The ZnO bandgap wasincreasingly blue-shifted for films of decreasing crystallite size, approaching+0.3 eV at dimensions of 2–3 nm. The nonlinear bandgap response correlated well with the Brusmodel. This work represents an experimental demonstration of quantum confinement usingALD on two- and three-dimensional substrates.

Characterization of polyolefin melts using the polymer reference interaction site model integral equation theory with a single‐site united atom model

AbstractA general approach, based on the polymer reference interaction site model (PRISM) integral equation theory, suitable for characterizing arbitrarily complex polyolefin melts is described. We tested the method by calculating the melt structures of linear polyethylene (PE) and isotactic polypropylene (iPP) and the spinodal decomposition temperatures for PE/iPP blends. The computational expense of the PRISM calculation was reduced with a single‐site united atom model in which the polyolefin CH, CH2, and CH3 groups were approximated as chemically equivalent sites with spherically symmetric energetic interactions. The site–site interactions were defined by a potential function comprising a hard core with an attractive Lennard–Jones term. These energetic parameters were optimized with a central composite design strategy that enabled a simultaneous fit of experimental melt density and structure factor data. Values were obtained for PE and iPP individually and for common universal parameters that could potentially be used for all polyolefins. The rotational isomeric state–metropolis Monte Carlo (RMMC) technique was used to generate sets of conformers at specified temperatures covering the melt‐temperature range of the polymers. The characteristic ratio was used to assess the quality of the conformers and the RMMC method. Values of 9.68 for PE and 9.27 for iPP were obtained. The single‐chain structure factors calculated by the RMMC method were used to calculate the total structure factor for each melt. These were validated against published X‐ray diffraction results. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1803–1814, 2001

Application of experimental design approach to the optimization of supercritical fluid extraction of polychlorinated biphenyls and polycyclic aromatic hydrocarbons

Extraction variables (pressure and temperature) were optimized by using a central composite experimental design strategy for the supercritical fluid extraction (SFE) of incurred polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) from sediment using 100% CO 2 and CO 2 containing 2% and 10% (v/v) of MeOH. Under the optimum SFE extraction conditions, the recoveries for total PCBs and PAHs were higher than with Soxhlet extraction (15%). The lower precision obtained by SFE vs. Soxhlet extraction (R.S.D. = 9.0 and 3.7%, respectively) was accounted for by the higher number of chromatographic determinations, since SFE extracts were recovered in three fractions.