In this study, a plastic deformation process consisting of hot compression at 350 °C and heat treatment at 400 °C was performed to bond AZ31 magnesium alloy. Microstructural evolution around the bonding interface was systematically characterized to investigate the bonding process and clarify the bonding mechanism. When the plastic deformation strain reached 0.6, the bonding zone was full of fine dynamic recrystallized grains and the initial interface was eliminated. The post-heating treatments were conducted to achieve a sound interface bonding. The tensile tests and the corresponding fracture morphologies analysis indicated that the optimum holding time of heat treatment was 8 h. The interfacial bonding strength of the specimens holding for 8 h reached 164.7 MPa, an enhancement of about 9% compared with that of the specimens holding for 1 h. The microstructure analysis indicated that the bonding quality was affected by migration of the interfacial grain boundary (GB), the development... [more]

Different analyses and feasibility studies have been conducted on the plant extracts of thyme (Thymus vulgaris), European horse chestnut (Aesculus hippocastanum), Nordmann fir (Abies nordmanniana), and snowdrop (Galanthus elwesii) to evaluate bio-based alternatives to common petrol-based stabilisers. For this purpose, in this study, plant extracts were incorporated into poly-lactic acid films (PLA) at different concentrations. The films’ UV absorbance and migration into packed food was analysed via photometric assays (ABTS radical cation scavenging capacity assay, β-carotene assay) and GC−MS analysis. Furthermore, the synergistic antioxidant effects of various combinations of extracts and isolated active compounds were determined. This way, antioxidant effects can be increased, allowing for a highly effective use of resources. All extracts were successfully incorporated into PLA films and showed notable photoabsorbing effects, while no migration risk was observed. Depending on extract... [more]

It is well-known that the addition of randomly dispersed particles in polymers influences their linear viscoelastic behavior and dynamic mechanical properties. The aim of this study was to describe the viscoelastic behavior of an epoxy resin modified by waste glass and rubber particles using the linear fractional spring-pot model. Unlike complex classical exponential models, fractional models, being only two-parameter dependent, make it easier to characterize the viscoelastic behavior of materials. Isothermal relaxation and single frequency sweep temperature dynamic tests were carried out in a dynamic mechanical analyzer DMA150 by varying the content of the particles from 0 to 20% by weight. Overall, the results of this study evidence that using waste materials as additives for polymer compounds is a practical and sustainable possibility when it comes to modifying their viscoelastic properties.

Carbon nanotubes are a promising adsorbent for desulfurization and denitrification. In this paper, Cu- and Cr-doped TiO2 supported by multi-walled carbon nanotubes (MWCNTs/Cu-Cr-TiO2) were synthesized by the sol-gel method. Characterizations of the samples were performed by TEM, XPS, XRD, DRS, and BET. The experiments of simultaneous desulfurization and denitrification were conducted in a fixed-bed reactor. The results showed that the adsorbent with a Cu to Cr molar ratio of 3 displays excellent adsorption property. The SO2 and NO adsorption capacity of MWCNTs/Cu-Cr-TiO2 (Cu/Cr = 3) were 36.83 and 12.34 mg/g under the optimal experimental operating parameters (SO2 content: 1575 mg/m3, NO content 736 mg/m3, O2 content 8%, H2O content 5%, and space velocity 1003 h−1). The adsorption capacity of MWCNTs/Cu-Cr-TiO2 was significantly better than that of the adsorbent doped with Cu or Cr alone (MWCNTs/Cu-TiO2 and MWCNTs/Cr-TiO2). Compared with single metal doping, bimetallic multivalent state... [more]

In this work, polymerizations of styrene (St) in the presence of divinylbenzene (DVB) as a crosslinking agent and sodium 4-vinylbenzenesulfonate (VBS) have been performed in Pickering emulsions, using silica nanoparticles (SNps) as stabilizing agents and ammonium persulfate as a hydrophilic initiator. In oil-in-water Pickering emulsions with alkaline continuous phase (pH = 9) at 1, 2, and 3 wt% DVB (relative to St), polydisperse spheroid copolymer submicronic nanoparticles were obtained. Comparatively, polymerizations performed in Pickering emulsions with acidic continuous phase (pH = 5) allowed preparing St-co-DVB microspheres with core−shell structures at 1 wt% DVB and St-co-DVB hybrid monoliths with bi-continuous morphologies at 2 and 3 wt% DVB. It is noteworthy that this work reports Pickering emulsion polymerization as a new strategy for preparing hybrid percolated scaffolds with bi-continuous porosity. The proposed mechanisms originated by pH, DVB, and VBS and the drastic impact... [more]

We report on an open-source, publicly available C++ software module called Chrono::GPU, which uses the Discrete Element Method (DEM) to simulate large granular systems on Graphics Processing Unit (GPU) cards. The solver supports the integration of granular material with geometries defined by triangle meshes, as well as co-simulation with the multi-physics simulation engine Chrono. Chrono::GPU adopts a smooth contact formulation and implements various common contact force models, such as the Hertzian model for normal force and the Mindlin friction force model, which takes into account the history of tangential displacement, rolling frictional torques, and cohesion. We report on the code structure and highlight its use of mixed data types for reducing the memory footprint and increasing simulation speed. We discuss several validation tests (wave propagation, rotating drum, direct shear test, crater test) that compare the simulation results against experimental data or results reported in... [more]

Aluminum oxides and hydroxides are widely applied because of the great variety of their modifications. In particular, aluminum oxides and hydroxides are used in petrochemistry and oil refining. However, amorphous aluminum compounds have not been sufficiently studied due to the complexity of their synthesis and the problems encountered during their study. The study of amorphous aluminum compounds is hindered by the ambiguity of terminology. In this work, the structures of amorphous aluminum compounds prepared by different methods and the properties that determine their applications have been highlighted in detail. Amorphous aluminum compounds play both positive and negative roles in petrochemistry; however, in petroleum refining, amorphous compounds (without promoters and transition metal salts) demonstrate a promising catalytic performance in oil upgrading.

Fe3O4 nanoparticles with cluster structure are superparamagnetic particles with applicability in various high-tech fields. In this study, the influence of surface modification with polyacrylic acid (PAA), a polymeric precursor, on the characteristics of Fe3O4 nanoparticles was investigated. The particles were synthesized by the polyol method and surface modified with various amounts of PAA. The surficial, structural, optical, and magnetic properties of the PAA-modified Fe3O4 nanoparticles were analyzed, confirming that negatively charged carboxyl groups were formed on the particle surface, and the particle dispersibility was enhanced by surface modification. This arises from an increase in the electrostatic repulsive force due to the surface functional groups. Functionalization promoted dissociation of the cluster particles, which became more pronounced as the PAA content increased. The optical parameters changed with the PAA content. Analysis of the magnetic properties showed that the... [more]

Magnetic gel abrasive finishing is a high-precision polishing method that uses magnetic forces to attract and restrain a gel abrasive, composed of aqueous slime gel, steel grits, and silicon carbon (SiC), for polishing workpieces. However, the magnetic adsorption performance of the gel abrasive will drop quickly when polishing non-ferromagnetic material such as stainless-steel or brass. Moreover, centrifugal force will push out the gel abrasive from the machining surface reducing the stability of polishing. Therefore, this paper developed a rotating cylinder-based magnetic finishing setup to allow the gel abrasive and workpieces to tumble and rotate together during the polishing process. To make the gel abrasive produce irregular and complicated movement paths for improving the polishing performance, this study first analyzed and compared the average surface roughness and removed material weight of workpieces using three kinds of motor operating modes; a unidirectional trapezoidal wave... [more]

Development of gas sensors displaying improved sensing characteristics including sensitivity, selectivity, and stability is now possible owing to tunable surface chemistry of the sensitive layers as well as favorable transport properties. Herein, zinc ferrite (ZnFe2O4) nanoparticles (NPs) were produced using a microwave-assisted hydrothermal method. ZnFe2O4 NP sensing layer films with different thicknesses deposited on interdigitated alumina substrates were fabricated at volumes of 1.0, 1.5, 2.0, and 2.5 µL using a simple and inexpensive drop-casting technique. Successful deposition of ZnFe2O4 NP-based active sensing layer films onto alumina substrates was confirmed by X-ray diffraction and atomic force microscope analysis. Top view and cross-section observations from the scanning electron microscope revealed inter-agglomerate pores within the sensing layers. The ZnFe2O4 NP sensing layer produced at a volume of 2 μL exhibited a high response of 33 towards 40 ppm of propanol, as well as... [more]

In this paper, the dynamic evolution of nanoparticles in a turbulent Taylor−Couette flow was studied by means of a numerical simulation. The initial particle size was 200 nm, and the volume concentration was 1 × 10−5. The Reynolds-averaged N−S equation for Taylor−Couette flow was solved numerically using the realizable k-ε model combined with the standard wall function. The numerical result of the velocity distribution is in good agreement with the experimental results. Additionally, the dynamic equation for the particle number distribution function was solved numerically using the Taylor series expansion moment method (TEMOM). The variation characteristics of particle number density, diameter and polydispersity in the flow were analyzed. The results show that particle breakage is obvious in the region with strong vorticity due to the large shear strength, which leads to a significant change in the particle number density, diameter and polydispersity. Furthermore, the effects of the ga... [more]

Industry-sponsored research has intensified to find suitable substitutes for synthetic polymers. For this purpose, biopolymers are promising materials that are extracted from renewable resources. However, there are areas of concern (biopolymers are mostly brittle in the dry state) that require further research before they are used in advanced applications. To overcome this, plasticizers are often added to biopolymers to enhance their physicochemical properties. In this study, chitosan (CH)-glycerol (GL)-based polymeric films were prepared by a simple drop-casting technique, and the influence of a plasticizer (GL) on the properties of chitosan films was analyzed. Additionally, the as-prepared samples were irradiated with γ-rays (60Co γ rays with a dose of 102 kGy) to study the effect of γ-irradiation on the properties of polymeric composites. To achieve this, different samples were prepared by varying the amount of GL. FT-IR analysis revealed the interruption of hydrogen bonding in chit... [more]

Products from castor seeds have been widely used in various fields. In order to study the breaking behavior and rupture mechanism of castor seed episperm during coat shelling process, the force-structure property of coating castor seed was investigated by a self-developed texture analyzer with in situ optical microscopic observation. Influences of compression distance, velocity and working temperature were studied. The results showed that castor seed episperm rupture commonly happened from the tail end to the first end. Compression distance effect can change the episperm cracking degree. Under pressing distance 2−3 mm, the episperm easily cracked into two flaps, and the breaking force stabilized at 77 N. Pressing velocity has no significant effect on episperm breaking. Temperature changes the physical property. With an increase in temperature, breaking force presents a “slope” decline; under a temperature of 120 ℃, temperature effect on the breaking force decreased significantly and th... [more]

The development of small semiconductor molecules such as the maleiperinone, have gained importance due to their applications in optoelectronics. In this work semiconductor films composed by a polymer matrix of PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) and maleiperinone were manufactured. The films used in the studies were deposited by vacuum evaporation and spin-coating techniques. Atomic force microscopy (AFM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Infrared spectroscopy were used for the analysis of morphological and structural films. The fundamental and the onset of the direct and indirect band gaps were also obtained by UV-vis spectroscopy. The band-model theory and the Density-functional theory (DFT) calculations were applied to determine the optical parameters. The dipole moment is 3.33 Db, and the high polarity gives a signal of the heterogeneous charge distribution along the structure of maleiperinone. Simple devices we... [more]

Apart from the conventionally used iron (Fe) and aluminum (Al) electrodes in microalgae harvesting, experiments were designed to examine the viability of lead (Pb), magnesium (Mg), zinc (Zn), and copper (Cu) as electrode materials in the harvesting of microalgae. The effect of voltage on the flocculation efficiency (FE) of the electrode materials was examined and compared. By dividing the optimal FE values by their corresponding periods, a simple yet practical approach was used to rank the electrode materials. From highest to lowest flocculation efficiency, the results were as follows: Cu, Zn, Mg, Al, and Pb at 10 V; Mg, Zn, Cu, Al, and Pb at 20 V; and Mg, Zn, Al, Cu, and Pb at 30 V. Important factors such as temperature, periodic FE, consumption of electrode material, pH, and metallic concentrations in the effluent were evaluated. The temperature increase proposed to have been affected by electric resistance drop and anodic corrosion, between 1.7 °C and 3.3 °C, 5 °C and 8.9 °C, and 10... [more]

The mixed ionic-electronic conducting (MIEC) oxygen transport membrane (OTM) can completely selectively penetrate oxygen theoretically and can be widely used in gas separation and oxygen-enriched combustion industries. In this paper, dual-phase MIEC OTMs doped with Bi are successfully prepared by a sol-gel method with high-temperature sintering, whose chemical formulas are 60wt.0.9Pr0.1O2−δ-40wt.%Pr0.6Sr0.4Fe1−xBiO3−δ (60CPO-40PSF1−xBO, x = 0.01, 0.025, 0.05, 0.10, 0.15, 0.20). The dual-phase structure, element content, surface morphology, oxygen permeability, and stability are studied by XRD, EDXS, SEM, and self-built devices, respectively. The optimal Bi-doped component is 60wt.0.9Pr0.1O2−δ-40wt.%Pr0.6Sr0.4Fe0.99Bi0.01O3−δ, which can maintain 0.71 and 0.62 mL·min−1·cm−2 over 50 h under He and CO2 atmospheres, respectively. The oxygen permeation flux through these Bi-doped OTMs under air/CO2 gradient is 12.7% less than that under air/He gradient, which indicates that the Bi-doped OTMs... [more]

Metal oxide nanoparticles have great potential for selective adsorption and catalytic degradation of contaminants from aqueous solutions. In this study, we employ mass spectrometry and molecular dynamics simulations to better understand the chemical and physical mechanisms determining the affinity of chlorobenzenes and polychlorinated biphenyls (PCBs) for zinc oxide nanoparticles (ZnO NPs). The experiments and simulations both demonstrate that the adsorption coefficients for chlorobenzenes increase steadily with the number of chlorine atoms, while, for PCBs, the relation is more complex. The simulations link this complexity to chlorine atoms at ortho positions hindering coplanar conformations. For a given number of chlorine atoms, the simulations predict decreasing adsorption affinity with increasing numbers of ortho substitutions. Consequently, the simulations predict that some of the highest adsorption affinities for ZnO NPs are exhibited by dioxin-like PCBs, suggesting the possibili... [more]

Piezoelectric PVDF sensors offer a unique option for the measurement of cavitation aggressiveness represented by the magnitude of impacts due to cavitation bubble collapses near walls. The aggressiveness measurement requires specific sensor shape and area, whereas commercial PVDF sensors are fabricated in limited geometry and size ranges. The photolithography method offers a possibility of production of home-made PVDF sensors of arbitrary shape and size. The methodology of a unique application of the standard photolithography method, which is commonly used for the production of printed circuit boards, is described in this paper. It enables mass production of high quality sensors contrary to laboratory techniques. This paper deals with the fabrication and the calibration of a photolithographically home-made PVDF sensor for the cavitation impact load measurement. The calibration of sensors was carried out by the ball drop method. Sensors of different sizes were fabricated by the photolit... [more]

For electrochemical supercapacitors, nickel cobaltite (NiCo2O4) has emerged as a new energy storage material. The electrocapacitive performance of metal oxides is significantly influenced by their morphology and electrical characteristics. The synthesis route can modulate the morphological structure, while their energy band gaps and defects can vary the electrical properties. In addition to modifying the energy band gap, doping can improve crystal stability and refine grain size, providing much-needed surface area for high specific capacitance. This study evaluates the electrochemical performance of aluminum-doped Ni1−xAlxCo2O4 (0 ≤ x ≤ 0.8) compounds. The Ni1−xAlxCo2O4 samples were synthesized through a hydrothermal method by varying the Al to Ni molar ratio. The physical, morphological, and electrochemical properties of Ni1−xAlxCo2O4 are observed to vary with Al3+ content. A morphological change from urchin-like spheres to nanoplate-like structures with a concomitant increase in the... [more]

The degradation kinetics of Direct Blue 15 (DB15), a diazo dye, were studied over a suspended and immobilized TiO2 catalyst. For all experiments, the kinetics experiments were performed in a swirl flow photoreactor under the influence of UV light. The effect of different parameters: dye concentration, catalyst loading, and light intensity, on the DB15 kinetics was investigated. The kinetic rates were assessed using apparent (ka) approach, a single value of reaction rate (kr) and adsorption constant (K), and approach of kr as of variable. The DB15 mineralization was discussed as well. Using a dip-coating device, the P25 catalyst was deposited on a Pyrex glass. The thin film surface characterization was examined. The coated catalyst was evaluated by checking the effect of two variables: initial dye concentration and light intensity on the DB15 kinetics. In terms of the ka approach, the results demonstrated that DB15 degradation is described by the pseudo first-order kinetics model.... [more]

In this study, nanoparticles of five photocatalytic systems based on pure zinc oxide and with rare earths ions M-ZnO (M = La3+, Ce3+, Pr3+ or Nd3+) calcined at 500 °C or 700 °C were synthesized and investigated as potential photocatalysts for the removal of dyes. The addition of rare earth ions causes a decrease in the bandgap of ZnO; therefore, it can be well used to improve the photocatalytic properties. The photocatalytic activity of the synthesized nanoparticles was evaluated by the degradation of Rhodamine B in the presence of H2O2 under ultraviolet illumination. The results indicate that all the synthesized nanoparticles show good dye degradation efficiency. The highest degradation efficiency was 97.72% for the Ce-ZnO sample calcined at 500 °C and was achieved in 90 min with an excellent constant of the dye degradation rate k = 0.0363 min−1 following a first-order kinetic mechanism. The presence of oxychlorides as secondary phases inhibits the rate of the photocatalytic reaction.

Environmental and human health are threatened by anthropogenic heavy metal discharge into watersheds. Traditional processes have many limitations, such as low efficiency, high cost, and by-products. Photocatalysis, an emerging advanced catalytic oxidation technology, uses light energy as the only source of energy. It is a clean new technology that can be widely used in the treatment of organic pollutants in water. Given the excellent adaptability of photocatalysis in environmental remediation, it can be used for the treatment of heavy metals. In this comprehensive review, the existing reported works in relevant areas are summarized and discussed. Moreover, recommendations for future work are provided.

Periodontitis is a chronic infectious disease worldwide, caused by the accumulation of bacterial plaque, which can lead to the destruction of periodontal supporting tissue and eventually tooth loss. The goal of periodontal treatment is to remove pathogenic factors and control the periodontal inflammation. However, the complete regeneration of periodontal supporting tissue is still a major challenge according to current technology. Tissue engineering recovers the injured tissue through seed cells, bio-capable scaffold and bioactive factors. Three-D-bioprinting is an emerging technology in regeneration medicine/tissue engineering, because of its high accuracy and high efficiency, providing a new strategy for periodontal regeneration. This article represents the materials of 3D bioprinting in periodontal regeneration from three aspects: oral seed cell, bio-scaffold and bio-active factors.

As the problems of electromagnetic pollution and interference are becoming increasingly serious, the development of electromagnetic absorption materials with a high absorption capacity and broad absorption bandwidth are stringently needed. In this work, an N-doped 2D carbon/Ni complex is synthesized through direct microwave irradiation on a mixed solution of nickel nitrate, urea, and agarose under N2. The electromagnetic absorption performance can be tuned by controlling the Ni content. Specifically, minimum reflection loss values (RLmin) of −65.5 dB at 15.8 GHz with an effective absorption bandwidth (EAB) of 4.2 GHz at a sample thickness of 1.47 mm, and −55.4 dB at 11.8 GHz with an EAB of 3 GHz at a sample thickness of 1.92 mm can be obtained. The outstanding performance of electromagnetic absorption is attributed to the multiple polarization relaxation processes and the synergistic effect between 2D carbon sheets and Ni particles.

Gamma-alumina nanoparticles (γANPs) were obtained from a low-cost process by using natural bauxites. The γANPs materials were characterized by X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), Brunauer−Emmett−Teller (BET) theory, scanning electron microscopy (SEM), atomic force microscopy (AFM), and were functionalized with N-cetyl-N, N, N, trimethylammonium bromide (CTAB), leading to CTAB modified γ-alumina nanoparticles (γANPs-CTAB). These novel functionalized γANPs-CTAB were characterized by XRPD, FTIR, and were used as an adsorbent for bisphenol-A (BPA) removal from water. Batch investigations were conducted under different experimental conditions (e.g., adsorbent dose, agitation time, initial concentration, and pH and surfactant loading) in order to optimize BPA adsorption and to identify the adsorption mechanisms in the system γANPs-CTAB-BPA. The effect of pH on the adsorption showed that the quantity of BPA removed increased remarkably until the pH... [more]