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LuFeO 3 particles were synthesized via a hydrothermal route, where the influence of various experimental parameters on the products was systematically investigated. XRD analysis reveals that single o-LuFeO 3 samples can be synthesized at reaction temperatures of 160–260 °C, reaction times of 24–60 h, NaOH concentrations of 0.625–6.25 M, and Lu 3+ /Fe 3+ ion concentrations of 0.025–0.075 M. SEM observation shows that LuFeO 3 particles prepared at relatively low temperatures (160–220 °C) and low NaOH concentrations (0.625–3.75 M) exhibit bar-like shape, and the aspect ratio of the bars decreases with increasing the temperature and NaOH concentration. At relatively high temperatures (240–260 °C) and high NaOH concentrations (5–6.25 M), the resulted LuFeO 3 particles are shaped like spheres, polyhedrons or cubes. The samples prepared at the temperature of 220 °C and the NaOH concentration of 2.5–3.75 M have a relatively large particle size. All the particles exhibit a layered structure, indicating that they are mainly constructed from irregular sheets. Compared to the reaction temperature and NaOH concentration, the reaction time and Lu 3+ /Fe 3+ concentration has a relatively small effect on the morphology and size of LuFeO 3 particles. The as-prepared LuFeO 3 samples have a similar bandgap energy of 2.14 eV and exhibit a week ferromagnetic behavior at room temperature.

WC-doped ZrB 2 –ZrSi 2 ceramic composites were fabricated by hot pressing at temperatures ranging from 1450 °C to 1550 °C. The influence of ZrSi 2 content on the mechanical properties of the composites was investigated by means of three point bending test and single edge notched-beam test, respectively. The microstructure and phase composition were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. The results revealed that: (i) the highest relative density was 99.5% for the composite fabricated at 1550 °C; (ii) the doping of WC refined the grain size and led to an anisotropic grain growth which was evidenced by the occurrence of elongated grains; (iii) the highest strength and fracture toughness were 585 MPa and 6.87 MPa m 1/2 , respectively; (iv) the main toughening mechanism was considered as the pull out of elongated grains and the deflection of cracks.

Calcium titanate (CaTiO3) nanoparticles with different average sizes were prepared by a polyacrylamide gel route, where the particle size was tailored by using different chelating agents. Scanning electron microscope observation shows that the samples prepared by using the chelating agents EDTA, acetic acid, tartaric acid, and citric acid have an average particle size of 25, 33, 36, and 55 nm, respectively. All the particles are regularly shaped like spheres. The bandgap energy of the four samples is measured to be 3.66–3.59 eV by ultraviolet (UV)–visible diffuse reflectance spectroscopy. The photocatalytic activity of the prepared CaTiO3 samples was evaluated by the degradation of methyl orange under 254 nm UV irradiation, revealing that they exhibit a good photocatalytic activity. Hydroxyl radicals are revealed, by the photoluminescence technique using terephthalic acid as a probe molecule, to be produced on the irradiated CaTiO3 nanoparticles and suggested to be the primary active species toward the dye degradation.

BiFeO3 particles with different morphologies and sizes were synthesized via a hydrothermal process, where the morphology and size was tailored by using different KOH concentrations in precursor solution. The samples prepared at n(KOH) = 3, 4.5, 6, and 7.5 M are composed, respectively, of octahedron-shaped particles (500–600 nm), cube-like particles (200–500 nm), irregular spherical agglomerates (9–16 μm) formed from disk-like grains with diameter of 1.4–2.8 μm and thickness of 0.2 μm, and cuboid-shaped particles with length-to-width ratio of 1.4:1–3.5:1 and width size ranging from 80 to 280 nm. Ag nanoparticles were deposited on the surface of BiFeO3 particles by a chemical reduction method to produce Ag@BiFeO3 nanocomposites. The photocatalytic activity of prepared samples was evaluated by degrading rhodamine B under simulated sunlight irradiation. It is demonstrated that Ag-decorated BiFeO3 particles exhibit an enhanced photocatalytic activity compared to bare BiFeO3 particles. This can be explained by the effective transfer of photogenerated electrons from the conduction band of BiFeO3 to Ag nanoparticles and hence increased availability of holes for the photocatalytic reaction. Hydroxyl radicals were detected by the photoluminescence technique using terephthalic acid as a probe molecule and are found to be produced over the irradiated BiFeO3 and Ag@BiFeO3 photocatalysts; especially, an enhanced yield is observed for the latter.

Ni-doped ZnO diluted magnetic semiconductors nanorods were successfully synthesized by hydrothermal method. The crystal structure, morphology, constituent elements and optical proprety of the products using this method were investigated via X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray energy dispersive spectrometry (XEDS) and ultraviolet-visible spectroscopy (UV-vis). The experiment results show that the morphology of samples were nanorods with good dispersion, all the diffraction peaks correspond to the wurtzite structure hexagonal phase, no other impurity phase appeare, and the Ni2+ions successfully substituted for the lattice site and generate single-phase Zn1-xNixO. The band gap increases firstly and reduces afterward with the increase of Ni2+contents.

In order to investigate the influence of carbon fiber’s surface state on the interlaminar shear properties of carbon fiber-reinforced plastic (CFRP) laminate, the carbon fiber’s surface state was modified by thermal treatment at elevated temperatures. The interlaminar shear strength (ILSS) of CFRP laminates reinforced with treated fibers was measured by means of short-beam shear test, and the surface state of fiber was characterized by Electron Spectroscopy for Chemical Analysis (ESCA) analysis to reveal the dominate factor for controlling the ILSS. Combining the ILSS measurement with the ESCA analysis, the results indicated that: (1) the ILSS is strongly dependent on the oxygen-containing functional groups on the surface of carbon fiber; (2) the fiber treated at 600 °C has the highest oxygen-containing functional groups that lead to the highest ILSS of CFRP; and (3) at temperatures beyond 600 °C, the oxygen-containing functional groups decrease with increasing the heat treatment temperature, resulting in...

For investigating the influence of thermal treatment on the thermo-mechanical stability and the carbon fiber's surface composition, the T300 carbon fibers were thermally treated at temperatures ranging from 600 °C to 1500 °C. After treatment, the thermal stability and microstructure were analyzed by mass change and XRD measurement. The mechanical properties and the surface composition of carbon fibers were measured as a function of temperature by the single filament tensile test technique and ESCA analysis, respectively. The results indicated that T300 fiber had good thermal stability and high temperature mechanical properties. To some extent, the high temperature treatment could lead to a further graphitization of carbon fiber. The surface composition measured by ESCA revealed that the oxygen concentrations on the surface of fibers significantly decreased from 17.97% for as-received fiber to 1.97% for 1500 °C treated fibers. But the relative content of graphite-like carbon increased from 42.97% for as-received fibers to 53.13% for 1500 °C treated fibers. Such composition would result in a decreased surface activity of carbon fiber.

With the addition of ZrSi2, the highly densified ZrB2-based ceramics were fabricated by hot pressing. The relative density increased with increasing the volume fraction of ZrSi2­and sintering temperature; the Vickers hardness increased with increasing the sintering temperature, but decreased with increasing the volume fraction of ZrSi2­.

In order to investigate the influence of carbon fiber’s surface state on the mechanical properties and the fiber-matrix interaction of CFRP, the change of surface state was achieved by thermal treatment of carbon fibers at elevated temperatures, and the surface state was characterized by XPS. The mechanical properties were measured from the flexural test. The CFRP reinforced with 600 °C treated fabrics containing the highest reactive functional groups, showed the highest flexural strength and modulus. But in the case of CFRP reinforced with 1500 °C treated fabrics containing the lowest reactive functional groups, exhibited the lowest flexural strength and modulus. Combining the mechanical properties with the microstructure analysis, the results indicated that the fiber-matrix interaction (strong or weak) depends on the relative percentage of reactive functional groups present on the carbon fiber surface.

Since fiber-matrix interface strength is critical to properties of carbon fiber-reinforced composites, measurement and analysis of interface strength are crucial steps in tailored design of composites. In the present work, the single fiber push-out test and the short-beam shear test were applied to measure the fiber-matrix interface strength in uni-directionally and two-directionally carbon fiber-reinforced phenolic resin matrix composites. The technical difficulties in processing the specimen and in realizing the fiber push-out were also discussed and clarified. For obtaining the successful test, typically, the thickness of the specimen should be smaller than 100 mm. During the fiber push-out, the de-bonding and fiber sliding at the interface were analyzed from the load-displacement curve features. The results indicated that both methods could be applied to determine the interface strength. The single fiber push-out and the short-beam shear tests resulted in a similar phenomenon in regard to the interface strength of uni-directionally and two-directionally carbon fiber-reinforced phenolic resin matrix composites, but expressed different values. The low interface strength measured from the short-beam shear test could be associated with multiple interlaminar shear failures. Furthermore, it was found that the interface strength of uni-directionally carbon fiber-reinforced phenolic resin matrix composites is somewhat higher than that of two-directionally carbon fiber-reinforced phenolic resin matrix composites. The difference in the interface strength could be attributed to the thermally induced residual stresses caused by the coefficient of thermal expansion mismatch of fiber and matrix. The approaches applied in the current work can be used for the evaluation of the interface strength of carbon fiber-reinforced phenolic resin matrix composites with different fiber-matrix bonding properties.

A new indicator to represent a maximum capacity expansion rate of distillation processes is presented in this article. A hydraulics-based heuristic strategy consisting of three levels is proposed to address the capacity expansion retrofit redesign of distillation systems. The first level is to evaluate an existing process to get the indicator which reflects quantitatively the capacity expansion rate, where a fractional utilization of area (FUA) method is also employed to screen the process bottlenecks. In the second level, the indicator is used to find the available debottlenecking measures from a measure library which is based on heuristics. In the last level, a new economy indicator called specific annual cost (SAC) is used to sort the available debottlenecking measures, and the corresponding process flowsheets and operation parameters are determined. An industrial capacity expansion retrofit for a light-ends separation plant is conducted so as to evaluate the performance of the proposed indicators and strategy in screening the available retrofit alternatives. Modifications on feeding location, operating pressure, number of theoretical stages, and feeding thermal condition, etc. are proposed to remove the bottlenecks. The maximum capacity expansion rate of the plant is about 40.0%, and the near-optimum retrofit options for different capacity expansion rates such as 20%, 25%, 30%, 35% and 40% are also presented. The results show that the proposed capacity expansion strategy is capable to resolve the issues associated with the retrofit redesign in a systematic and relatively simple way.

Ag nanoparticles were successfully synthesized by hydrothermal method under the polyol system combined with traces of sodium chloride, Silver nitrate(AgNO3) and polyvinylpyrrolidone (PVP) acted as the silver source and dispersant respectively. The samples by this process were characterized via X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED) to determine the chemical composition, particle size, crystal structure and morphology. The experiment results indicate that the crystal structure of the samples is face centered cubic (FCC) structure as same as the bulk materials, The specific surface area is 24 m2/g, the particle size distribution ranging from10 to 50 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results.

We report here the synthesis of TbMnO3 nanoparticles via an acrylamide gel route. XRD, TG analysis, DSC analysis, and FTIR spectroscopy are combinatively used to investigate the thermal decomposition process of precursor xerogels and the formation of TbMnO3 phase. It is demonstrated that high-phase-purity TbMnO3 nanoparticles can be prepared by using different chelating agents at a sintering temperature of 800 °C. SEM observation and XRD analysis reveal that the particle size and morphology of the products have a dependence on the chelating agent. The particles prepared using citric acid as the chelating agent appear to be regularly spherical in shape and highly uniform in size with a diameter of ∼67 nm, while the sample prepared by using the chelating agent EDTA mainly consists of sphere-, ellipsoid-, and rod-like particles and exhibits a relatively broad particle size distribution with an average particle size centered around 115 nm. The use of a combination of citric acid and EDTA generally results in sphere- and ellipsoid-like particles with an average particle size between those of the samples prepared separately by using the two chelating agents.

In the protecting inert gas, Aluminum nanoparticles were successfully prepared by anodic arc discharge plasma method. The morphology, particle size, crystal microstructure and specific surface area of the particles by this process were characterized via X-ray powder diffraction (XRD), Brunauer–Emmett–Teller(BET) adsorption equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED). The experimental results indicate that the crystal structure of the samples is face centered cubic (fcc) structure as same as the bulk materials, the particle size distribution ranging from 20 to 70 nm, with an average particle size about 44 nm obtained by TEM and confirmed by XRD and BET results. The specific surface area is 41 m2/g, the nanopowders distributed uniformly in spherical chain shapes with uniform size and monodisperse particles.

In this paper, Silver nitrate(AgNO3) and polyvinylpyrrolidone (PVP) acted as the silver source and dispersant respectively, the silver nanowires including a small amount of folded structure of silver nanowires, were synthesized by hydrothermal method under the polyol system combined with traces of sodium chloride. The nanowires were characterized by X-ray powder diffraction(XRD), transmission electron microscopy(TEM), selected area electron diffraction(SAED), scanning electron microscopy (SEM), energy dispersive spectrometry (EDAX) and UV-vis absorption spectroscopy to determine the chemical composition, crystal structure, morphology,and the generation mechanism of Ag nanowires was also analysed. The experimental results showed that the crystal structure of the as-prepared Ag nanowires was fcc structure with uniform width, smooth surface, the diameter about 200nm,the average length about 15μm,and the aspect ratio up to 75.The folded structure of silver nanowires synthesized were due to the straight silver nanowires were connected in an end-to-end manner, with obvious spacing between them.

Helical structure ZnS were successfully prepared via solvothermal method by the reaction of zinc acetate and sodium sulphide. The composition, morphology, and microstructure of the sample were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), the corresponding selected area electron diffraction (SAED) and X-ray energy spectrum (EDS). The experiment results show that the sample is 1-D hexagonal crystal ZnS and grows along the [002] direction, and is helical structure, with lengths in the range of 100-200 nm, the diameter about 5-15 nm, and pitch about 20nm.

In this report, a polyacrylamide gel route is introduced to synthesize Bi 2 Fe 4 O 9 nanoparticles. It is demonstrated that high-phase-purity Bi 2 Fe 4 O 9 nanoparticles can be prepared using different chelating agents. Interestingly, however, the particle size of the products is found to be dependent on the choice of chelating agent. The use of EDTA as the chelating agent allows the production of Bi 2 Fe 4 O 9 nanopowder with a relatively smaller particle size. The photocatalytic experiments reveal that the as-prepared Bi 2 Fe 4 O 9 nanoparticles possess excellent photocatalytic activity for oxidative decomposition of methyl red under ultraviolet and visible light irradiation. Magnetic hysteresis loop measurement shows that the Bi 2 Fe 4 O 9 nanoparticles exhibit a weak ferromagnetic behavior at room temperature.

Copper nanoparticles were successfully prepared in large scales by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by X-ray diffraction (XRD), BET equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED). The experiment results indicate that the crystal structure of the samples is fcc structure as same as that of the bulk materials. The specific surface area is is 11 m2/g, with the particle size distribution ranging from 30 to 90 nm, the average particle size about 67nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles have uniform size, higher purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

BiFeO3microcylinders were synthesized via a hydrothermal condition. SEM observation reveals that with increasing the hydrothermal reaction time from 6 to 15 h, the microcylinders grow from ~0.7 to ~4.1 μm in height, whereas their diameter remains to be 3.7-3.8 μm with a minor change. The microcylinders are mainly made up of sphere-like grains of 100–150 nm in size. A possible growth mechanism of the BiFeO3microcylinders is proposed. The photocatalytic activity of the as-prepared BiFeO3samples was evaluated by the degradation of acid orange 7 under simulated sunlight irradiation, revealing that they possess an appreciable photocatalytic activity. Magnetic hysteresis loop measurement shows that the BiFeO3microcylinders exhibit a typical antiferromagnetic behavior at room temperature.

BiFeO 3 nanoparticles with different average grain sizes have been prepared through a polyacrylamide gel route. In the present synthesis route, the grain size is tailored by varying the ratio of bis-acrylamide to acrylamide. The photocatalytic activity of the as-prepared BiFeO 3 nanoparticles has been investigated by the degradation of methyl orange (MO), a typical azo dye. It is revealed that the products exhibit a pronounced photocatalytic activity under ultraviolet as well as visible-light irradiation. With decrease in particle size, the photocatalytic activity exhibits a rising trend. The influences of catalyst dosage and initial dye concentration on the photocatalytic efficiency have been also investigated. In the present experiments, the optimum loading of BiFeO 3 nanoparticles and initial concentration of MO are obtained to be ~ 2.5 g L −1 and ~ 10 mg L −1 , respectively.

In this work, a polyacrylamide gel route is introduced to synthesize YMn 2 O 5 nanoparticles. It is demonstrated that high-quality YMn 2 O 5 nanoparticles with a uniform size and spherical shape can be prepared using different chelating agents. However, the average particle size of the products is found to have a dependence on the choice of the chelating agent. The sample prepared using citric acid as the chelating agent has an average particle size of ~ 45 nm, while the sample prepared by using the chelating agent EDTA has a particle size centered around 70 nm. The optical energy bandgap of the citric acid- and EDTA-resulted samples is obtained, from optical absorption measurements, to be 1.21 and 1.17 eV, respectively. The photocatalytic experiments reveal that the as-prepared YMn 2 O 5 nanoparticles exhibit an interesting photocatalytic activity for oxidative decomposition of methyl red under ultraviolet and visible-light irradiation.

The following problems have been studied: the precolation threshold of jointed rock masses, the Representative Elementary Volume, the permeability of rock masses with impersistent rock joints and the permeability variation with depth. The proposed simple methods are verified against the results of numerical computation and the Stripa Project, Sweden.

SYNOPSIS The initial shear stiffness and normal stiffness are discussed together with their inter-relation; The compliance matrix for a jointed rock mass is developed and a method for calculating the limiting values and directions' of modulus is recommended.