Desulfurization ability of refining slag with medium basicity

The desulfurization ability of refining slag with relative lower basicity (B) and Al₂O₃ content (B = 3.5–5.0; 20wt%–25wt% Al₂O₃) was studied. Firstly, the component activities and sulfide capacity (C_S) of the slag were calculated. Then slag-metal equilibrium experiments were carried out to measure the equilibrium sulfur distribution (L_S). Based on the laboratorial experiments, slag composition was optimized for a better desulfurization ability, which was verified by industrial trials in a steel plant. The obtained results indicated that an MgO-saturated CaO-Al₂O₃-SiO₂-MgO system with the basicity of about 3.5–5.0 and the Al₂O₃ content in the range of 20wt%–25wt% has high activity of CaO (a_CaO), with no deterioration of C_S compared with conventional desulfurization slag. The measured L_S between high-strength low-alloyed (HSLA) steel and slag with a basicity of about 3.5 and an Al₂O₃ content of about 20wt% and between HSLA steel and slag with a basicity of about 5.0 and an Al₂O₃ content of about 25wt% is 350 and 275, respectively. The new slag with a basicity of about 3.5–5.0 and an Al₂O₃ content of about 20wt% has strong desulfurization ability. In particular, the key for high-efficiency desulfurization is to keep oxygen potential in the reaction system as low as possible, which was also verified by industrial trials.     

A study on nano-sized NiO electrodes doping with C and Co prepared by electrochemical deposition-sintering processes and their capacitance performance

In the present work, it was studied that nanoosized NiO electrodes doping with C and Co were prepared by electrochemical deposition in an ethanol solution containing nickel nitrate and cobalt nitrate and sintering processes. The capacitance performance of such electrodes was also studied. The results reveal that samples obtained by electrochemical deposition first on a porous nickel cathode in an ethanol solution contain 0.5 mol/L nitrates, in which Ni(NO3)2 and Co(NO3)2 were mixed in a molar proportion of 8 : 2. After sintering at 300℃ for 2 h, they exhibited the best performance. XRD analysis illustrates that the essential phase of the product is NiO doping with certain content of C and Co. The particles of product imaged a spherical morphology with sizes of 20---30 nm in diameter, and with an average crystal size of 4--5 nm. The capacitance measurement of the simulating C/NiO capacitors indicates that a single electrode can reach as high as 410.0 F/g, and still maintain the value of 323 F/g after 30 recycles showed as a stabilized value with increasing recycles, when it was discharged at a current of 5 mA.     

Effectiveness of sodium silicate as gangue depressants in iron ore slimes flotation

The recovery of iron from the screw classifier overflow slimes by direct flotation was studied. The relative effectiveness of sodium silicates with different silica-to-soda mole ratios as depressants for silica and silicate bearing minerals was investigated. Silica-to-soda mole ratio and silicate dosage were found to have significant effect on the separation efficiency. The results show that an increase of Fe content in the concentrate is observed with concomitant reduction in SiO₂ and Al₂O₃ levels when a particular type of sodium silicate at a proper dosage is used. The concentrate of 58.89wt% Fe, 4.68wt% SiO₂, and 5.28wt% Al₂O₃ with the weight recovery of 38.74% and the metal recovery of 41.13% can be obtained from the iron ore slimes with 54.44wt% Fe, 6.72wt% SiO₂, and 6.80wt% Al₂O₃, when Na₂SiO₃ with a silica-to-soda mole ratio of 2.19 is used as a depressant at a feed rate of 0.2 kg/t.     

Microwave absorption properties of SiC@SiO2@Fe3O4 hybrids in the 2-18 GHz range

To enhance the microwave absorption performance of silicon carbide nanowires (SiCNWs), SiO₂ nanoshells with a thickness of approximately 2 nm and Fe₃O₄ nanoparticles were grown on the surface of SiCNWs to form SiC@SiO₂@Fe₃O₄ hybrids. The microwave absorption performance of the SiC@SiO₂@Fe₃O₄ hybrids with different thicknesses was investigated in the frequency range from 2 to 18 GHz using a free-space antenna-based system. The results indicate that SiC@SiO₂@Fe₃O₄ hybrids exhibit improved microwave absorption. In particular, in the case of an SiC@SiO₂ to iron(Ⅲ) acetylacetonate mass ratio of 1:3, the microwave absorption with an absorber of 2-mm thickness exhibited a minimum reflection loss of -39.58 dB at 12.24 GHz. With respect to the enhanced microwave absorption mechanism, the Fe₃O₄ nanoparticles coated on SiC@SiO₂ nanowires are proposed to balance the permeability and permittivity of the materials, contributing to the microwave attenuation.     

用于低品位热能储蓄的盐浸渍阳极氧化铝复合材料的合成与表征

Thermochemical heat storage (THS) systems have recently attracted a lot of attention in research and development. In this study, an anodic aluminum oxide (AAO) template, fabricated by a two-step anodization method, was used for the first time as the matrix material for a THS system. Different salts were studied as thermochemical materials for their suitability in low-grade heat storage application driven by solar energy for an open system. Compositions were prepared by absorbing CaCl₂, MgCl₂, LiCl, LiNO₃ and mixtures of these salts under a vacuum in an AAO matrix. Field Emission Scanning Electron Microscopy was used to examine the morphology of the produced AAO composites. Thermal energy storage capacities of the composites were characterized using a differential scanning calorimeter. Characterization analysis showed that anodized Al plates were suitable matrix materials for THS systems, and composite sorbent prepared with a 1:1 ratio LiCl/LiNO₃ salt mixture had the highest energy value among all composites, with an energy density of 468.1 kJ·kg?1.     

ENSO frequency change in coupled climate models as response to the increasing CO<Subscript>2</Subscript> concentration

The response of ENSO frequency to the increasing CO2 concentration and associated mechanism are examined with outputs of four coupled climate models (GFDL/CM2.0,CNRM/CM3,IPSL/CM4 and INM/CM3.0) submitted to the IPCC Fourth Assessment Report (IPCC AR4).Results reveal a significant change of ENSO frequency as response to the increasing CO2 concentration.However,such a change exhibits an evident model dependence.The ENSO frequency tends to increase in GFDL/CM2.0 and CNRM/CM3 models and decreases in IPSL/CM4 an...     

Polyimide/titanium dioxide self-cleaning nano-hybrid films with high photocatalytic properties

Self-cleaning films are considered an emerging paradigm of environmentally functional materials.Enhancing the photocatalytic activities of self-cleaning film is a viable strategy for improving its antifouling characteristics.In this work,a polyimide/titanium dioxide(TiO₂) film(PI/TiO₂) film was developed by casting a mixture of polyamic acid solution and TiO₂ hydrosol with a subsequent thermal imidization.TiO₂ with a concentration of 1,3,and 5 wt% was ...     

Effect of NaCl on synthesis of ZrB2 by a borothermal reduction reaction of ZrO2

ZrB₂ powders were synthesized via a borothermal reduction reaction of ZrO₂ with the assistance of NaCl under a flowing Ar atmosphere. The optimal temperature and reaction time were 1223 K and 3 h, respectively. Compared with the reactions conducted without the addition of NaCl, those performed with the addition of an appropriate amount of NaCl finished at substantially lower temperatures. However, the addition of too much NaCl suppressed this effect. With the assistance of NaCl, a special morphology of polyhedral ZrB₂ particles covered with ZrB₂ nanosheets was obtained. Moreover, the experimental results revealed that the special morphology was the result of the combined effects of B₂O₃ and NaCl. The formation of the special microstructure is explained on the basis of the "dissolution-recrystallization" mechanism.     

In situ reaction mechanism of MgAlON in Al-Al2O3-MgO composites at 1700℃ under flowing N2

The Al-Al₂O₃-MgO composites with added aluminum contents of approximately 0wt%, 5wt%, and 10wt%, named as M₁, M₂, and M₃, respectively, were prepared at 1700℃ for 5 h under a flowing N₂ atmosphere using the reaction sintering method. After sintering, the Al-Al₂O₃-MgO composites were characterized and analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results show that specimen M₁ was composed of MgO and MgAl₂O₄. Compared with specimen M₁, specimens M₂ and M₃ possessed MgAlON, and its production increased with increasing aluminum addition. Under an N₂ atmosphere, MgO, Al₂O₃, and Al in the matrix of specimens M₂ and M₃ reacted to form MgAlON and AlN-polytypoids, which combined the particles and the matrix together and imparted the Al-Al₂O₃-MgO composites with a dense structure. The mechanism of MgAlON synthesis is described as follows. Under an N₂ atmosphere, the partial pressure of oxygen is quite low; thus, when the Al-Al₂O₃-MgO composites were soaked at 580℃ for an extended period, aluminum metal was transformed into AlN. With increasing temperature, Al₂O₃ diffused into AlN crystal lattices and formed AlN-polytypoids; however, MgO reacted with Al₂O₃ to form MgAl₂O₄. When the temperature was greater than (1640 ±10)℃, AlN diffused into Al₂O₃ and formed spinel-structured AlON. In situ MgAlON was acquired through a solid-solution reaction between AlON and MgAl₂O₄ at high temperatures because of their similar spinel structures.     

Direct electrochemistry and electrocatalysis of horseradish peroxidase in MnO2 nanosheet film

A novel material MnO2 nanosheet has been used as the support matrix for the immobilization of horseradish peroxidase （HRP）. HRP entrapped in MnO2 nanosheet film exhibits facile direct electron transfer with the electron transfer rate constant of 6.86 s^-1. The HRP/MnO2 nanosheet film gives a reversible redox couple with the apparent formal peak potential （E^0＇） of -0.315 V （vs. Ag/AgCl） in pH 6.5 phosphate buffer solution （PBS）. The formal potential E^0＇ of HRP shifts linearly with pH with a slope of -53.75 mV.pH^-1, denoting that an electron transfer accompanies single-proton transportation. The immobilized HRP shows an electrocatslytic activity to the reduction of H2O2. The response time of the biosensor for H2O2 is less than 3 s, and the detection limit is 0.21 μmol · L^-1 based on signal/noise = 3.     

Direct electrochemistry and electrocatalysis of horseradish peroxidase in MnO_2 nanosheet film

A novel material MnO2 nanosheet has been used as the support matrix for the immobilization of horseradish peroxidase (HRP). HRP entrapped in MnO2 nanosheet film exhibits facile direct electron transfer with the electron transfer rate constant of 6.86 s-1. The HRP/MnO2 nanosheet film gives a re- versible redox couple with the apparent formal peak potential (E0′) of -0.315 V (vs. Ag/AgCl) in pH 6.5 phosphate buffer solution (PBS). The formal potential E0′ of HRP shifts linearly with pH with a slope of -53.75 mV·pH-1, denoting that an electron transfer accompanies single-proton transportation. The immobilized HRP shows an electrocatalytic activity to the reduction of H2O2. The response time of the biosensor for H2O2 is less than 3 s, and the detection limit is 0.21 μmol·L-1 based on signal/noise = 3.     

汽车暴露面板带有表面条状缺陷的夹杂物分布特征分析:一种定量电解方法

The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface. A quantitative electrolysis method was used to compare and evaluate the three-dimensional morphology, size, composition, quantity, and distribution of inclusions in the defect and non-defect zone of automobile exposed panel. The Al₂O₃ inclusions were observed to be aggregated or chain-like shape along with the sliver defect of about 3–10 μm. The aggregation sections of the Al₂O₃ inclusions are distributed discretely along the rolling direction, with a spacing of 3–7 mm, a length of 6–7 mm, and a width of about 3 mm. The inclusion area part is 0.04%–0.16% with an average value of 0.08%, the inclusion number density is 40 mm?2 and the inclusion average spacing is 25.13 μm. The inclusion spacing is approximately 40–160 μm, with an average value of 68.76 μm in chain-like inclusion parts. The average area fraction and number density of inclusions in the non-defect region were reduced to about 0.002% and 1–2 mm?2, respectively, with the inclusion spacing of 400 μm and the size of Al₂O₃ being 1–3 μm.     

Immobilization of Hemoglobin on Platinum Nanoparticles-Modified Glassy Carbon Electrode for H_2O_2 Sensing

This work described an amperometric hydrogen peroxide (H2O2) biosensor based on immobilization of hemoglobin (Hb) on a glassy carbon (GC) electrode modified by platinum nanoparticles, which was prepared by an in situ chemical reductive growth method. The electrochemical impedance measurements confirmed that the Hb was immobilized on the platinum nanoparticles-modified glassy carbon surface and has a synergistic effect with platinum nanoparti-cles in improving the catalytic reduction of H2O2. The Hb immobilized platinum nanoparticles-modified GC (Hb/Pt/GC) electrode displays an effective catalytic response to the reduction of H2O2. A linear dependence of the catalytic current versus H2O2 concentration was obtained in the range of 5.0×10-6 to 4.5×10-4 mol·L-1 with a detection limit (S/N=3) of 7.4×10-7 mol·L-1.     

Synthesis and characterization of salt-impregnated anodic aluminum oxide composites for low-grade heat storage

Thermochemical heat storage(THS) systems have recently attracted a lot of attention in research and development. In this study, an anodic aluminum oxide(AAO) template, fabricated by a two-step anodization method, was used for the first time as the matrix material for a THS system. Different salts were studied as thermochemical materials for their suitability in low-grade heat storage application driven by solar energy for an open system. Compositions were prepared by absorbing CaCl_2, MgCl_2, LiCl, LiNO_3 and mixtures of these salts under a vacuum in an AAO matrix. Field Emission Scanning Electron Microscopy was used to examine the morphology of the produced AAO composites. Thermal energy storage capacities of the composites were characterized using a differential scanning calorimeter. Characterization analysis showed that anodized Al plates were suitable matrix materials for THS systems, and composite sorbent prepared with a 1:1 ratio LiCl/LiNO_3 salt mixture had the highest energy value among all composites, with an energy density of 468.1 k J·kg~(-1).     

Hydrogen Adsorption on Metal-Organic Framework MOF-177

This review summarizes the recent literature on the synthesis, characterization, and adsorption properties of meal-organic framework MOF-177. MOF-177 is a porous crystalline material that consists of Zn4O tetrahedrons connected with benzene tribenzoate (BTB) ligands. It is an ideal adsorbent with an exceptionally high specific surface area (BET4500 m2/g), a uniform micropore size distribution with a median pore diameter of 12.7 ?, a large pore volume (2.65 cm3/g), and very promising adsorption properties for hydrogen storage and other gas separation and purification applications. A hydrogen adsorption amount of 19.6 wt.% on MOF-177 at 77 K and 100 bar was observed, and a CO2 uptake of 35 mmol/g on MOF-177 was measured at 45 bar and an ambient temperature. Other hydrogen properties (kinetics and heat of adsorption) along with adsorption of other gases including CO2, CO, CH4, and N2O on MOF-177 were also be discussed. It was observed in experiments that MOF-177 adsorbent tends to degrade or decompose when it is exposed to moisture. Thermogravimetric analysis showed that the structure of MOF-177 remains intact at temperatures below 330℃ under a flow of oxygen, but decomposes to zinc oxide at 420℃.     

Kaolin-based geopolymers with various NaOH concentrations

Kaolin geopolymers were produced by the alkali-activation of kaolin with an activator solution (a mixture of NaOH and sodium silicate solutions). The NaOH solution was prepared at a concentration of 6–14 mol/L and was mixed with the sodium silicate solution at a Na₂SiO₃/NaOH mass ratio of 0.24 to prepare an activator solution. The kaolin-to-activator solution mass ratio used was 0.80. This paper aimed to analyze the effect of NaOH concentration on the compressive strength of kaolin geopolymers at 80℃ for 1, 2, and 3 d. Kaolin geopolymers were stable in water, and strength results showed that the kaolin binder had adequate compressive strength with 12 mol/L of NaOH concentration. When the NaOH concentration increased, the SiO₂/Na₂O decreased. The increased Na₂O content enhanced the dissolution of kaolin as shown in X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. However, excess in this content was not beneficial for the strength development of kaolin geopolymers. In addition, there was the formation of more geopolymeric gel in 12 mol/L samples. The XRD pattern of the samples showed a higher amorphous content and a more geopolymer bonding existed as proved by FTIR analysis.     

Global evolution of an analyzer angle on the Faraday anomalous dispersion optical filter at 1529 nm

In order to realize laser frequency stabilization, the todal lution of an analyzer angle on the electrodeless-discharge-vapor- lamp-based excited-state Faraday anomalous dispers, filter （LESFADOF） with a single transmission peak operating on the Rb1529 nm （5P3/2-4Ds/2） is presented. We find the nsmission of the line center peak at -80° arrives at 14% in a 3 cm length lamp contained natural Rb mixed with 2 torr Xe butte operating at 250℃ with 176 MHz radio frequency. When it is used to realize laser frequency stabilization, the LESFADOF -80° is appropriate. Whether a single transmission peak or double transmission peaks depend on the rf voltage when two polarizers are crossed.     

Photoluminescence and cathodoluminescence properties of a novel CaLaGa307：Dy3＋ phosphor

A single host white emitting phosphor, CaLaGa3O7:Dy3+, was synthesized by chemical co-precipitation. Field emission scanning electron microscopy, X-ray diffraction, laser particle size analysis, and photoluminescence and cathodoluminescence spectra were used to investigate the structural and optical properties of the phosphor. The phosphor particles were composed of microspheres with a slight tendency to agglomerate, and an average diameter was of about 1.0 μm. The Dy3+ ions acted as luminescent centers, and substituted La3+ ions in the single crystal lattice of CaLaGa3O7 where they were located in Cs sites. Under excitation with ultraviolet light and a low voltage electron beam, the CaLaGa3O7:Dy3+ phosphor exhibited the characteristic emission of Dy3+ (4F9/2-6H15/2 and 4F9/2-6H13/2 transitions) with intense yellow emission at about 573 nm. The chromaticity coordinates for the phosphor were in the white region. The relevant luminescence mechanisms of the phosphor are investigated. This phosphor may be applied in both field emission displays and white light-emitting diodes.     

Enhanced microwave absorption properties of rod-shaped Fe2O3/Fe3O4/ MWCNTs composites

A novel type of composite absorber,i.e.Fe_2O_3/Fe_3O_4/MWCNTs composites(0%,1.7%and 5%MWCNTs),with microwave absorption properties was successfully fabricated by a facile hydrothermal method.The preparedα-Fe_2O_3/Fe_3O_4nanoparticles displayed rod-shaped morphology.The complex permittivity and permeability of the Fe_2O_3/Fe_3O_4/MWCNTs composites distinctly increased,furthermore,with the introduction of MWCNTs,the Fe_2O_3/Fe_3O_4/MWCNTs composites exhibited fine microwave absorption performance with strong absorption and wide absorption band.In particular,for Fe_2O_3/Fe_3O_4/1.7%MWCNTs composite with an absorber thickness of 2.5 mm,the reflection loss(RL)reached a minimum of-44.1 d B at 10.4 GHz and the effective absorption bandwidth(RL-10 d B)covered 3.3 GHz.The enhanced microwave absorption performance of the Fe_2O_3/Fe_3O_4/MWCNTs composites was attributed to the high dielectric loss and improved impedance matching which was closely related to the rod-shaped morphology of Fe_2O_3,Fe_3O_4and the introduction of MWCNTs.