Using a New Fe3O4@CPAM Magnetic Flocculant and Microwave to Demulsify Heavy Oil-in-Water Emulsions.

In this study, cationic polyacrylamide (CPAM)-coated magnetic nanoparticles (MNPs) Fe3O4@CPAM were synthesized for treating heavy O/W emulsions. This Fe3O4@CPAM was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM) techniques, and its synergistic performances with microwaves were evaluated in detail with respect to the microwave radiation power, radiation time, and magnetic nanoparticle concentration. On this basis, the distribution of oil droplets and the wettability and chargeability of magnetic nanoparticles were measured without or with microwave radiation using biomicroscopy, contact angle measurement instrument, and a ζ-potential analyzer, thus revealing the synergistic demulsification mechanism between microwave and magnetic nanoparticles. The results showed that excessively high or low microwave radiation parameters had an inhibitory effect on the magnetic nanoparticle demulsification, and microwave promoted the magnetic nanoparticle demulsification only when the radiation parameters were in the optimal range. In addition, the water separation rate showed an increasing and then decreasing trend with the increase of magnetic nanoparticles concentration, with or without microwave action. As an example, the water separation rate of the emulsion for 1 h was 21.34% when the Fe3O4 concentration was 175 mg/L without microwave action, while it increased to 55.56% with microwave action. In contrast, when the concentration of Fe3O4@CPAM was 175 mg/L, the water separation rate was 42.86% without microwave radiation, while it was further increased to 77.38% under microwave radiation. These results indicate that magnetic nanoparticles and their complexes significantly affect the water separation process under different conditions. There is a more obvious coupling synergistic effect between Fe3O4@CPAM and microwave. This was due to the lower absolute potential of Fe3O4@CPAM and its higher hydrophobicity.

Study on the Effect of Polymer-Modified Magnetic Nanoparticles on Viscosity Reduction of Heavy Oil Emulsion.

To overcome the problems of large dosage, fast sedimentation, and the unsatisfactory emulsification effect of traditional magnetic nanoparticles, polymer-modified magnetic nanoparticle Co3O4@HPAM was synthesized as an emulsifier for heavy oil O/W emulsion by modifying the surface of Co3O4. The composition of Co3O4@HPAM was characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy. Then, the effects of the mass fraction of magnetic nanoparticles before and after modification on the stability and rheology of the emulsion were compared and analyzed. The experiments show that the degree of reduction of the water-separation rate under the action of Co3O4@HPAM was 13 times higher than that under the action of Co3O4 at the same mass fraction. By using Co3O4@HPAM, the water separation of the emulsion was only 6.74% at 4 h, while the viscosity reduction was greater than 97% at a mass fraction of 0.04%. Finally, combined with the test results of zeta potential, interfacial tension, contact angle, and oil droplet distribution, the effect mechanism of Co3O4@HPAM on the viscosity reduction of heavy oil emulsification was investigated. It is found that the polymer-modified magnetic nanoparticles have stronger negative electricity, a larger contact angle, and smaller interfacial tension, while the oil droplets under their action have a smaller radius and a more homogeneous distribution. The research in this paper provides a theoretical basis for the application of magnetic nanoparticles in heavy oil emulsification and viscosity reduction technology.

A thorough mechanistic study of ethanol, acetaldehyde, and ethylene adsorption on Cu-MOR via DFT analysis.

A comprehensive study combining the density functional theory (DFT) and ab initio thermodynamic analysis was conducted to unravel the active sites and adsorption mechanisms of ethanol, acetaldehyde, and ethylene on various copper-modified mordenite (Cu-MOR) configurations, including Cu3/MOR, Cu3O3/MOR, and Cu6/MOR. This research involved an exhaustive exploration of structural and formation energies, revealing that the formation energies of these structures are temperature-dependent. Despite all three structures thermodynamically accommodating ethanol adsorption, their respective adsorption mechanisms differ significantly. In Cu3/MOR, weak van der Waals interactions predominate, while strong Cu-OOH interactions in Cu6/MOR facilitate ethanol dehydration. Conversely, Cu3O3/MOR exhibits pronounced Cu3O3-HOH interactions that favor ethanol dehydrogenation. Notably, Cu3O3/MOR displays robust ethylene adsorption, which enhances the potential for further ethylene activation. In-depth Bader charge and density of states analyses underscore the varying strengths and electronic characteristics of these interactions. This research provides a theoretical foundation for the design of highly efficient Cu-MOR catalysts tailored for the selective conversion of ethanol.

Biomechanical evaluation of a novel atlas polyaxial transverse connecting screw system, an in vitro human cadaveric study.

PURPOSE: To introduce a novel transverse connecting screw system, and to evaluate the biomechanical stability of the novel screw system using human cadaveric specimens. METHODS: Six fresh-frozen cadaveric upper cervical spines were used in our study. Every specimen was tested under 5 conditions: intact group; unstable group; C1 to C2 screw rod system group; C1 to C2 + crosslink system group; atlas polyaxial transverse connecting screw (APTCS) system. RESULTS: Compared with the intact state, C1 to C2 screw rod system, C1 to C2 + CL system and APTCS showed statistically decrease range of motion in all directions except for the unstable group under posterior extension direction (P < .05). APTCS group has the least range of motion in all directions (P < .001). CONCLUSION: The APTCS system was able to restore stability to the atlantoaxial joint. APTCS system has the advantages of easy installation, convenient bone grafting, and strong biomechanical strength.

Efficient charge separation and transfer in a one-dimensional carbon nanotube/tungsten oxide p-n heterojunction composite for solar energy conversion.

Efficient and cost-effective photocatalysts for solar energy conversion represent a rapidly advancing and compelling area of research. In our study, we employed theoretical calculations to design a novel composite material consisting of a one-dimensional (1D) carbon nanotube (CNT) and tungsten oxide (W18O49) p-n heterojunction. This composite material was successfully synthesized using a straightforward solvothermal method, and we thoroughly investigated the charge separation and transfer mechanism. Our findings revealed that the composite material exhibited a superior photocurrent response. Notably, the CNTs/W18O49-2 sample demonstrated a significantly higher photocurrent under both AM 1.5G and infrared light irradiation, outperforming the individual components under AM 1.5G by a substantial factor of 30. This remarkable enhancement in performance can be attributed to the efficient charge separation and transfer facilitated by the built-in electric field created at the interface through the p-n heterojunction. Our study introduces a pioneering integration of CNTs and 1D tungsten oxide, resulting in a composite structure with a p-n heterojunction-a concept that has not been extensively explored previously. The results confirmed the formation of this unique one-dimensional structure and a p-n heterojunction, which has outstanding properties for various applications. These findings provide a robust foundation for the design of photocatalytic interfaces and offer a fresh approach to the development of high-performance photocatalysts.

Bifunctional electrocatalysts for oxygen reduction and oxygen evolution: a theoretical study on 2D metallic WO2-supported single atom (Fe, Co, or Ni) catalysts.

Catalysts play a critical role in the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) for energy storage, conversion, and utilization. Herein, first-principles density functional theory (DFT) calculations demonstrated that single-metal-atom (Fe, Co, or Ni) sites can bind to the surface of 2D WO2, enhancing the adsorption of intermediates involved in the OER/ORR. Furthermore, it was found that the single-metal-atom-doped 2D WO2 achieves the smallest OER and ORR overpotentials of 0.42 V and 0.40 V, respectively, which are comparable to those of IrO2 or Pt-based catalysts. This predicts the excellent OER/ORR catalytic activities of the single-metal-atom (Fe, Co, or Ni) doped 2D WO2, which would be a promising bifunctional catalyst for fuel cells, water splitting, and metal-air batteries.

The Role of Posterior Longitudinal Ligament in Cervical Disc Replacement: An Ovine Cadaveric Biomechanical Analysis.

BACKGROUND Cervical disc replacement (CDR) has been widely used to restore and maintain mobility and function of the treated and adjacent motion segments. Posterior longitudinal ligament (PLL) resection has been shown to be efficient in anterior cervical decompression and fusion. However, less is known about the biomechanical effect of PLL removal versus preservation in cervical disc arthroplasty. MATERIAL AND METHODS Three motion segments of 24 ovine cervical spines (C2-C5) were evaluated in a robotic spine system with axial compressive loads of 50 N. These cervical spines were divided in three groups according to the following conditions: (1) intact spine, (2) C3/C4 CDR with the Prestige LP prosthesis and PLL preservation, and (3) C3/C4 CDR with the Prestige LP prosthesis and PLL removal. The ranges of motion (ROMs) were recorded and analyzed in each group. RESULTS The C3/C4 ROM in group 3 (CDR with PLL removed) increased significantly in flexion-extension and axial rotation compared with group 1 (intact spine). Moreover, in flexion-extension, the mean total ROM was significantly larger in group 3 than in group 1. All the ROM observed in group 2 (CDR with PLL preserved) did not significantly differ from the ROM observed in group 1. CONCLUSIONS Compared with intact spines, CDR with PLL removal partly increased ROM. Moreover, the ROM in CDR with PLL preservation did not significantly differ from the ROM observed in intact spines. The PLL appears to contribute to the balance and stability of the cervical spine and should thus be preserved in cervical disc replacement provided that the posterior longitudinal ligament is not degenerative and the compression can be removed without PLL takedown.

Preparation and Application of Modified Magnetic Particles to Remove Phosphate in Aqueous Media.

In this work, magnetic particles were firstly protected by oleic acid, and then polymers, the polymers was prepared with allyl-thiourea as the functional monomer, ethyleneglycol dimethacrylate as the cross-linking agent, 2,2-azobisisobutyronitrile as the initiator, and acetonitrile as the solvent. The magnetic polymers were analyzed by FT-IR, X-ray diffraction, and a vibrating sample magnetometer to obtain the morphological and magnetic properties. The adsorption of phosphate on the magnetic polymers was investigated, including pH effect, initial concentration, and temperature. The results proved that the adsorbent was paramagnetic and successfully loaded with the poly-thiourea group. The data was well fitted to the Langmuir adsorption isotherm, and the maximum adsorption capacity was 55.20 mg-P g(-1). Furthermore, desorption of phosphate from the adsorbent could be achieved efficiently by 0.5 mol L(-1) NaOH, reusability was studied by repeating adsorption-desorption cycles five times.

High activity and stability in the cross-coupling of aryl halides with disulfides over Cu-doped hierarchically porous zeolite ZSM-5.

A Cu-doped zeolite ZSM-5 (Cu-ZSM-5-M) with a micro-meso-macroporous structure was directly synthesized, and it exhibits excellent catalytic activity and good recyclability in the cross-coupling of aryl halides with diphenyl disulfides. This feature should be attributed to the structural characteristics of meso-macropores and homogeneous dispersion of active Cu(δ+) (δ < 2) species in Cu-ZSM-5-M.

K4Nb6O17·4.5H2O: a novel dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III).

A series of orthorhombic phase K4Nb6O17·4.5H2O was synthesized via a hydrothermal approach. When presented in an acidic pH range, K4Nb6O17·4.5H2O showed a strong ability in quick reduction from Cr(VI) to Cr(III). The resulted Cr(III) ions were removed by an effective adsorption through simply adjusting the solution pH from strong acidity to near neutrality, owing to the sample's unique nano-sheet structure with a wide layer spacing. The Cr(III) ions adsorbed onto samples were released again for reusing by eluting with 1molL(-1) HCl solution, and K4Nb6O17·4.5H2O regenerated by immersing in a KOH solution. The reduction efficiency of Cr(VI) was still up to 98% after irradiation for 60min, and the removal efficiency of Cr(III) ions was as high as 83% even after five cycles. Therefore, K4Nb6O17·4.5H2O is clearly demonstrated to be an excellent dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III). The relevant materials reported herein might be found various environment-related applications.

Study on the degradation of the dye wastewater with polyaniline on titanium nanotubes.

Polyaniline/titanium nanotube composite (PANI/TNT) photocatalysts were prepared by 'in situ'chemical oxidative polymerization of aniline. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform IR spectra (FTIR) and UV-Visible spectroscopy measurements were used to characterize the obtained photocatalysts, and their photocatalytic activities were investigated by degrading Reactive Green19 (RG19) under near visible light irradiation (lambda = 365 nm). The content of PANI, pH, dosage, and concentration of RG19 were also investigated. The results showed that the inner diameter of the PANI/TNT was 6 nm and that the PANI did not change the structure of the TNT. The PANI was coated on the surface of the TNT. The light response of the PANI/TNT was extended to the visible-light regions. Among the six different kinds of photocatalysts, the 1.17 wt% PANI/TNT had the best performance in treating 10 ppm RG19. The best pH is 3 for the largely protonated surface of the composite at low pH. The adsorption amount was increased as the dosage increased. The decolonization efficiency decreased with increasing initial RG19 concentration. The performance of the photocatalyst in decomposing RG19 was stable after 5 time cycles.

Design and synthesis of metal sulfide catalysts supported on zeolite nanofiber bundles with unprecedented hydrodesulfurization activities.

Developing highly active hydrodesulfurization (HDS) catalysts is of great importance for producing ultraclean fuel. Herein we report on crystalline mordenite nanofibers (NB-MOR) with a bundle structure containing parallel mesopore channels. After the introduction of cobalt and molybdenum (CoMo) species into the mesopores and micropores of NB-MOR, the NB-MOR-supported CoMo catalyst (CoMo/NB-MOR) exhibited an unprecedented high activity (99.1%) as well as very good catalyst life in the HDS of 4,6-dimethyldibenzothiophene compared with a conventional γ-alumina-supported CoMo catalyst (61.5%). The spillover hydrogen formed in the micropores migrates onto nearby active CoMo sites in the mesopores, which could be responsible for the great enhancement of the HDS activity.