查看更多>>摘要：The synthesis of n-type phosphorus-doped diamond is essential for the development of diamond-based bipolar devices. Although demonstrated 20 years ago, it remains a complex problem due to low incorporation efficiency and low maximum concentrations. Previous works showed the deleterious influence of methinophosphide for-mation in a methane/hydrogen/phosphine plasma on the growth of phosphorous doped diamond using the chemical vapor deposition method. In this work, we investigate the effect of pulsing methane during microwave plasma enhanced chemical vapor deposition to avoid the formation of HCP and to increase phosphorus incor-poration efficiency and maximum concentration in diamond.
查看更多>>摘要：Bluecoke powder (BC) was used as a precursor to prepare porous carbon (MKBC) by microwave-assisted KOH activation. The physical and chemical properties of MKBC were investigated by SEM, FT-IR, Raman, and its adsorption performance for simulative organic wastewater was detected by ultraviolet spectrum analyses. Results indicated that the surface morphology of BC was changed by microwave-assisted KOH activation, resulting in abundant macropores and micropore structures on MKBC. The high porosity of the developed meso-and micropore structures on MKBC enhanced the adsorption capacity, with the maximum Langmuir adsorption capacity (qm) of 307.692 mg/g. The kinetics were more consistent with the pseudo-first-order model when the methylene blue concentration was 50 mg/L and with the Elovich model as the concentration further increased (150 mg/L). Moreover, MKBC showed high affinity toward methylene blue at low concentrations, and the removal rate of methylene blue was more than 99% in less than 1 h. The regeneration and applicability results showed that MKBC had significant stability and effectiveness, and had a certain removal effect on malachite green, rhodamine B, p-nitrophenol, and tetracycline in wastewater, in which p-nitrophenol was the best. Efficient and low-cost MKBC could play an important role in the treatment of organic wastewater and provide a new value-added utilization for BC.
查看更多>>摘要：Tribological behaviour of bio-lubricants is constantly evolving to be improved. Vegetable and synthetic oils owing the increasing interest of the environmental impact constitute a suitable alternative for lubrication. The addition of particles as additive show a great potential to improve the tribological properties of bio-lubricants. This paper overviewed the effect of graphite and hexagonal boron nitride (hBN) particles as additives on the tribological properties of different lubricating base oils such as mineral oil (dodecane), vegetable oil (moringa oil) and vegetable/dodecane blends. The addition of particles (0.5 and 1 w%) has indicated an improvement of the mineral base oil. At the addition of small amounts of moringa oil (MO), a reduction of about 55% of friction and wear performances of dodecane. We showed that the more promising results were obtained for the blend containing 3 w% of MO with hBN particles. These new formulations lubricant represent an excellent alternation for lubrication environmentally friendly.
查看更多>>摘要：Hierarchically porous carbon (HPC) derived from pig bone has been synthesized to meet the increasing demand of carbon-based anode electrode material for lithium-ion batteries (LIBs). Pig bone with unique structure and high content of inorganic minerals (Ca-3(PO4)(2), CaCO3) acting as self-template was selected as precursor for the preparation of porous carbon and no more additive agents were needed. When tested as anode material for lithium-ion batteries (LIBs), the as-obtained porous carbon exhibited excellent initial reversible capacity (1308 mAh g(-1) at 0.1 A g(-1)), superior cycling performance (640 mAh g(-1) at 0.5 A g(-1) after 500 cycles), and desired rate capability (304 mAh g(-1) at 5 A g(-1)). The outstanding electrochemical properties can be ascribed to the abundant existence of micropores, the specific microstructure, and doped with N and P elements.& nbsp;
查看更多>>摘要：Sensing behaviors of sulfur-doped silicon carbide nanotube (S-SiCNT) to propane and butane gases, which are parts of Liquefied Petroleum Gas (LPG), are investigated by calculations of adsorption energy, electronic band structure, density of states (DOS), sensitivity and charge transfer using first principle calculations based on density functional theory. Adsorption of propane or butane undergoes spontaneous exothermic reactions, resulting in chemisorptions. Propane or butane adsorption on S-SiCNT induces notable alteration of electronic structure of the nanotube, which causes electron transfer from the nanotube to the propane or butane (hole doping). The sensitivity to propane is found much higher than that to butane of S-SiCNT. The calculated sensitivities to propane and butane of S-SiCNT and charge transfer analyses underscore the significant sensor properties of S-SiCNT to detect LPG at room temperature.
Koltsova, T. S.Bobrynina, E. V.Larionova, T. V.Salynova, M. A....
8页
查看更多>>摘要：The addition of various types of carbon nanostructures in copper matrix was studied. Fullerene soot, CNTs and rGO showed that the type of nanocarbon affects the distribution of the additive in the matrix and on the formation of the composite structure. A comparative analysis of the structure and properties for composite materials with various types of nanocarbon was carried out. Composites containing CNTs have the most uniform structure and showed a significant increase in hardness up to 190 HV, with a coefficient of friction equal to 0.22 and thermal conductivity was 75% of pure copper.
Ozok, Hande IzemYardim, YavuzAli, Hoshyar SaadiBarzani, Hemn A. H....
7页
查看更多>>摘要：The aim of the present work is to describe voltammetric analysis of caffeic acid phenethyl ester (CAPE) by using a boron-doped diamond (BDD) electrode in the presence of the cationic surfactant. Using cyclic voltammetry, CAPE demonstrated a single well-defined, quasi-reversible, adsorption-controlled by oxidation and reduction peak at approximately +0.44 V & +0.22 V respectively, (vs. Ag/AgCl) in the Britton-Robinson buffer (BR, 0.04 mol L-1, pH 5.0). The obtained results showed that the oxidation peaks of CAPE are pH dependent (ranging from 2.0 to 6.0). The oxidation peak currents of CAPE were significantly increased by using cetyltrimethylammonium bromide (CTAB, cationic surfactant) in the selected supporting electrolyte. Under the optimum parameters of experiment, the linear relationship was found for CAPE determination in 0.04 mol L-1 BR buffer solution (pH 5.0) including 1 x 10(-4) mol L-1 CTAB at +0.41 V (vs. Ag/AgCl) (after 30 s accumulation at the open-circuit condition). The linear range was found with 0.01 to 1.0 mu g mL(-1) (3.5 x 10(-8)-3.5 x 10(-6) mol L-1) via the detection limit 0.0028 mu g mL(-1) (9.8 x 10(-9) mol L-1). The developed approach was used successfully to detect CAPE concentration in the model urine samples. To our knowledge, this is the first approach for electrochemically analyzing of CAPE.
查看更多>>摘要：A dynamically switchable electromagnetically induced transparency (EIT) based on metal-graphene hybrid metamaterial is proposed. The EIT metamaterial consists of two split-ring resonator (SRRs) and two orthogonal cut-wires (CWs) with different length. The EIT metamaterial illuminated by y-polarized and x-polarized incident waves exhibits two different EIT effects, which can be explained by multipole scattering theory and three-dimensional schematic diagrams. The simulated EIT spectra are almost identical to the theoretical EIT spectra calculated by the two-particle model. Two EIT effects and theirs group delays can be dynamically tunable by manipulating the Fermi level of graphene on two SRRs. Moreover, EIT metamaterial shows good sensing per-formance with the sensitivities of 0.185 THz/RIU and 0.160 THz/RIU in the x and y polarization directions, respectively. Our EIT metamaterial realizes dynamically switchable EIT effect and provides a novel approach for applications in slow light devices and sensors.
查看更多>>摘要：Unlike SiC unipolar devices, the on-state resistance of diamond unipolar devices based on bulk conduction has a negative temperature coefficient (NTC) which reduces the conduction losses at high junction temperatures. Thus, in order to associate these opposed temperature coefficients, the current article focuses on the modeling of a hybrid power device composed of a n-type 4H-SiC MOSFET and a p-type diamond bulk FET device. The optimal performances and sizing of SiC and diamond devices are introduced and calculated, as an initial benchmark under the same specifications. Based on an analytical modeling of both switching and conduction losses, junction temperatures and associated heatsink parameters, the hybrid device performances are evaluated for a synchronous buck converter operating at 1200 V-1 A and at an ambient temperature of 300 K. The results described in the manuscript highlight an equilibrium of the hybrid device total losses over a large range of temperatures as well as a reduction by two of the SiC active area. The proposed analysis could be further extended to different voltage/current classes to meet the requirements of alternative applications.
查看更多>>摘要：Diamond-like carbon (DLC) films represent promising surface treatments for biomedical implants. In this paper, using Raman and X-ray photoelectron spectroscopies, we analyzed the effects of secondary phases present in ZrO2 substrates on the structure of DLC films fabricated by plasma-based ion implantation and deposition method, and the structural stability of the films in response to applied indentation prints. The results revealed oxygen incorporation in DLC films from the oxide substrates during deposition, and a clear dependence of sp(3) carbon content on the oxygen fraction of the substrate and on gas pressure. Moreover, a pronounced structural distortion of the DLC films at the film/substrate interface was observed, which resulted from polymorphic transformation on the zirconia surface during deposition, while a pronounced change in Raman spectral morphology of carbon induced by structural alterations could also be observed around the indentation prints. The findings clearly pointed at the need to take into considerations the structural alterations of the DLC film structure at the interface associated with interfacial defects and film adhesion, especially for biomedical applications that involve surface loading.
NSTL
Elsevier