Synthesis of tetrahydrofuran from maleic anhydride on Cu–ZnO–ZrO2/H-Y bifunctional catalysts

A series of bifunctional Cu–ZnO–ZrO₂/H-Y catalysts of different compositions were prepared by coprecipitating sedimentation method and were characterized by surface area and XRD analyses. The catalytic performance in synthesis of tetrahydrofuran was evaluated and optimized in a three-phase slurry batch reactor. The experimental results showed that the appropriate ratio of Cu/ZnO in the hydrogenation catalyst was 50/45, for which the conversion of maleic anhydride (MA) and selectivity of tetrahydrofuran (THF) reached 100% and 46%, respectively, at 50 bar and 493 K after 6 h of operation. Also, according to these results, it was demonstrated that the incorporation of zirconium oxide in the catalyst formulation enhanced the catalytic activity, and tetrahydrofuran selectivity was increased to 55%. Ultimately, it was concluded that the bifunctional catalyst of Cu–ZnO–ZrO₂/H-Y was an appropriate catalyst to produce THF from MA with high activity, selectivity and stability.     

Synthesis of Dimethyl Ether over Modified H-Mordenite Zeolites and Bifunctional Catalysts Composed of Cu/ZnO/ZrO2 and Modified H-Mordenite Zeolite in Slurry Phase

A simple, cost effective and reusable transition metal (M = Ti, V, Mn)-grafted mesoporous silica spheres were synthesized by sol–gel technique and characterized by SXRD, FTIR, UV–Vis DRS, SEM, EDS, BET-surface area, pore volume and average pore diameter. Epoxidation of cyclohexene to cyclohexene oxide over these modified silica spheres using TBHP as oxidant was performed to compare the catalytic activities. Cyclohexene oxide selectivity was recorded to be 87.5% with 72.5% conversion over 8 wt% Ti-grafted silica spheres in comparison to V and Mn-grafted catalysts.     

酵母甘露糖蛋白体外发酵及其代谢产物的抗炎活性

通过体外肠道菌群厌氧发酵技术研究酵母甘露糖蛋白（mannoprotein,MP）的益生活性。结果表明,MP可调节肠道菌群结构,在门水平增加了拟杆菌门（Bacteroidetes）的相对丰度,降低了厚壁菌门（Firmicutes）、变形菌门（Proteobacteria）的相对丰度,降低了Firmicutes/Bacteroidetes比值。MP显著提高了发酵液中短链脂肪酸尤其是乙酸和丙酸的含量。MP与菊粉具有相似的益生菌活性,菊粉可促进双歧杆菌属（Bifidobacterium）的增殖,而MP可选择性促进拟杆菌属（Bacteroides）、韦荣球菌属（Veillonella）、Clostridium＿sensu＿srticto、布劳特氏菌属（Blautia）、粪杆菌属（Faecalibacterium）、纺锤链杆属（Fusicatenibacter）和产丁酸球菌属（Butyricicoccus）的生长。脂多糖诱导RAW 264.7巨噬细胞模型结果表明MP对炎症没有显著调节作用（P>0.05）,而其发酵液具有显著抗炎活性,且其活性与菊粉组相似,均优于空白组。因此,MP有望成为通过调...     

Effect of hexagonal structure nanoparticles on the morphological performance of the ceramic scaffold using analytical oscillation response

Porous bony scaffolds are utilized to manage the growth and migration of cells from adjacent tissues to a defective position. In the current investigation, the effect of titanium oxide (TiO₂) nanoparticles on mechanical and physical properties of porous bony implants made of polymeric polycaprolactone (PCL) is studied. The bio-nanocomposite scaffolds are prepared with composition of nanocrystalline hydroxyapatite (HA) and TiO₂ powder using the freeze-drying technique for different weight fractions of TiO₂ (0 wt%, 5 wt%, 10 wt%, and 15 wt%). In order to identify the microstructure and morphology of the fabricated porous bio-nanocomposites, the X-ray diffraction (XRD), atomic force microscope (AFM) and scanning electron microscopy (SEM) are employed. Also, the biocompatibility and biodegradability of the manufactured scaffolds are examined by placing them in a simulated body fluid (SBF) for 21 days, their weight and pH changes are measured. The rate of degradation of the PCL-HA scaffold can be controlled by varying the percentage of its constituent components. Due to an increasing growth and activity of bone cells and the apatite formation on the free surface of the fabricated bio-nanocomposite implants as well as their reasonable mechanical properties, they have the potential to be used as a bone substitute. Additionally, with the aid of the experimentally extracted mechanical properties of the scaffolds, the vibrational characteristics of a beam-type implant made of the proposed porous bio-nanocomposites are explored. The results obtained from SEM image indicate that the scaffolds produced by the employed method have high total porosity (70%–85%) and effective porosity. The pore size is obtained between 60 and 200 μm, which is desirable for the growth and propagation of bone cells. Also, it is revealed that the addition of TiO₂ nanoparticles leads to reduce the rate of dissolution of the fabricated bio-nanocomposite scaffolds.     

Vibrations of beam-type implants made of 3D printed bredigite-magnetite bio-nanocomposite scaffolds under axial compression: Application,communication and simulation

Due to the Si-O-Si bonding, silicate bioceramics have enhanced mechanical characteristics than their calcium phosphate (CaP) counterparts. Bredigite with orthorhombic crystal system is one of the most efficient bioceramics in osteoblast and bone growth. On the other hand, biosilicate-magnetite composites (e.g. bredigite-magnetite and hardystonite-magnetite) are excellent candidates for hyperthermia applications. In the current study, the vibrational response of a beam-type bone implant subjected to axial compression is investigated. The implant is made of bredigite-magnetite bio-nanocomposite scaffold fabricated by 3D printing machine including $0.8\mathit{mm}$ pore size. The Young's modulus of the scaffold is extracted experimentally corresponding to different magnetite nanoparticle (MNP) weight fractions, crystalline nanocomposite particle size, and various shapes of morphology. The morphology shape is determined corresponding to different MNP weight fractions and temperatures using scanning electron microscopy (SEM). Thereafter, an analytical solution is presented to express explicitly the load-frequency and frequency-deflection responses of the axially loaded beam-type bone implant. It is observed that in the prebuckling domain, by increasing the axial compressive load, the influence of the MNP weight fraction on the natural frequency of the bio-nanocomposite implant increases while in the postbuckling regime, increment in the axial compression has no effect on the significance of the MNP weight fraction effect.     

Synthesis and antibacterial activity of stable bio-conjugated nanoparticles mediated by walnut (Juglans regia) green husk extract

Nanoparticles have gained significant attention in recent years due to their numerous applications in various aspects of human life. A variety of methods have been investigated for synthesis of nanoparticles among which, biogenic approaches are considered as both simple and eco-friendly. Here, a new single-step biological approach was employed for synthesis of silver chloride nanoparticles (AgCl-NPs) at room temperature, using walnut green husk extract. Macromolecules present in the plant extract, which might act as bio-reductants and/or stabilisers of nanoparticles were characterised by Fourier transform Infrared spectroscopy. X-ray diffraction pattern and transmission electron microscopy revealed that 1 mM of AgNO3 produced mostly spherical nanoparticles in a range of 4–30 nm in diameter with an average of 16 nm. Interestingly, the synthesised nanoparticles showed significant inhibitory effects against Escherichia coli and Staphylococcus aureus clinical isolates. Altogether, these data suggest a new encouraging application of a medicinal plant bound with synthesised AgCl nanoparticles.     

Simulation of dielectric behavior in RFeO$$_{}$$ orthoferrite ceramics (R = rare earth metals)

Due to their colossal dielectric constant (CDC), \(\hbox {RFeO}_{3}\), orthoferrite ceramics (R = rare earth metal) have recently attracted much attention. In the present research, the dielectric constants of \(\hbox {RFeO}_{3}\) orthoferrite ceramics, whether with or without CDC, have been simulated. The type of synthesis method, the type of R material, temperature, and frequency as the effective parameters on the dielectric behavior are introduced to the model. Another input parameter is the ratio of \(\hbox {Fe}^{+2}/\hbox {Fe}^{+3}\) peak area (in the XPS diagram), which is the most important parameter that affects the CDC behavior. Initially, a colossal database is formed by means of WebPlotDigitizer software and 2930 experimental data, and then the simulation is carried out through gene expression programming. Two case studies are also performed on \(\hbox {PrFeO}_{3}\) and \(\hbox {NdFeO}_{3}\) orthoferrite ceramics to validate the accuracy of the presented model. \(\hbox {PrFeO}_{3}\) exhibits significant CDC behavior whereas the \(\hbox {NdFeO}_{3}\) ceramic samples possess little CDC property, both of which were precisely simulated by the model. Two-dimensional tenth-degree equations resulting from the model predict the dielectric constant variations accurately.     

Design of an adaptive-robust controller for a powder coating robot and its comparison with inverse dynamic approach

In this research, the design and function of “DAP”, a 3-DOF ‘RRP’ (rotational/prismatic) dual-acting pick-and-place-painting robot, are first briefly presented and, along with its kinematic and dynamic analysis, is studied to eliminate the man presence in industrially polluted environment such as coating processes. The main function of this robot is coating epoxy powder on “Hawle” gate valves at temperatures up to 200°C. Then, the movement and control simulation trend for maneuvering in optimization path are described by non-linear inverse dynamic and adaptive-robust controllers as modern control methods regarding to angle and torque feedback systems in industrial robots. Comparison of these control approaches is considered in relation to uncertainties. The results obtained from this research could greatly satisfy the need for overcoming uncertainties in such combined industrial processes.     

Mixing assessment of non-cohesive particles in a paddle mixer through experiments and discrete element method (DEM)

In this study the mixing kinetics and flow patterns of non-cohesive, monodisperse, spherical particles in a horizontal paddle blender were investigated using experiments, statistical analysis and discrete element method (DEM). EDEM 2.7 commercial software was used as the DEM solver. The experiment and simulation results were found to be in a good agreement. The calibrated DEM model was then utilized to examine the effects of the impeller rotational speed, vessel fill level and particle loading arrangement on the overall mixing quality quantified by the relative standard deviation (RSD) mixing index. The simulation results revealed as the impeller rotational speed was increased from 10?RPM to 40?RPM, generally a better degree of mixing was reached for all particle loading arrangements and vessel fill levels. As the impeller rotational speed was increased further from 40?RPM to 70?RPM the mixing quality was affected, for a vessel fill level of 60% and irrespective of the particle loading arrangement. Increasing the vessel fill level from 40% to 60% enhanced the mixing performance when impeller rotational speed of 40?RPM and 70?RPM were used. However, the mixing quality was independent of vessel fill level for almost all simulation cases when 10?RPM was applied, regardless of the particle loading arrangement. Furthermore, it was concluded that the particle loading arrangement did not have a considerable effect on the mixing index. ANOVA showed that impeller rotational speed had the strongest influence on the mixing quality, followed by the quadratic effect of impeller rotational speed, and lastly the vessel fill level. The granular temperature data indicated that increasing the impeller rotational speed from 10?RPM to 70?RPM resulted in higher granular temperature values. By evaluating the diffusivity coefficient and Peclet number, it was concluded that the dominant mixing mechanism in the current mixing system was diffusion.     

Deep oxidative desulfurization of gas oil based on sandwich-type polysilicotungstate supported β-cyclodextrin composite as an efficient heterogeneous catalyst

In this work, in order to obtain deep clean gas oil, a novel organic-inorganic hybrid (n-C₄H₉)₄N)₇H₅Si₂W₁₈Cd₄O₆₈@β-cyclodextrin (abbreviated as TBA-SiWCd@β-CD) composite was synthesized by supporting quaternary ammonium salt of sandwich-type polysilicotungstate on β-cyclodextrin (TBA-SiWCd@β-CD) as an efficient catalyst for oxidative desulfurization (ODS) of gas oil. The successful composition of the materials explained by the formation of host-guest inclusion complex, which confirmed through FTIR, UV-vis, XRD, SEM, and EDX characterization analyses. Experimental results revealed that the levels of sulfur content and mercaptan compounds of gas oil lowered with 97% removal efficiency. Compared with the ODS treatment of gas oil, the TBA-SiWCd@β-CD composite showed an outstanding catalytic performance for the oxidation of dibenzothiophene (DBT) in the prepared model fuel. The main factors that influence the desulfurization efficiency and the kinetic study of the ODS process were investigated. The prepared heterogeneous catalyst was found to give remarkable reusability for five runs without a discernible decrease in its activity. This study suggested the potential application of the TBA-SiWCd@β-CD catalyst for removal of hazardous sulfur compounds from gas oil fuel.