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The primary goal of this study is to examine the impact of sodium hydroxide (NaOH)/alkali-activated fly ash on the fresh properties and mechanical properties of self-compacting concrete (SCC). The fresh properties, known as the workability of SCC characteristics, were determined using the U-box, V-funnel, J-ring, and L-box tests. The M30 grade SCC containing superplasticizer of 0.86 wt. % of cement is replaced with 10%, 15%, 20%, 25%, 30%, and 40% of alkali-activated fly ash. On days 7, 14, and 28 after curing, the compressive strength and the splitting tensile strength of the SCC were examined. The study was further extended to evaluate the behavior of reinforced concrete beams containing fly ash and ground granulated blast furnace slag, whose size was 1200 × 100 × 150 mm3, under flexure loading. Based on the test results, it was found that the increase in the replacement of cement with alkali-activated fly ash increased the workability in the SCC. With the addition of superplasticizers, the SCC gained much more workability than conventional concrete containing no superplasticizer. The mechanical properties of 10% and 15% activated fly ash in Portland cement provided the maximum strength for the SCC at different ages of curing. The maximum first crack load and maximum ultimate flexure loading of the reinforced concrete beam containing 10% activated fly ash by weight of cement were greater than those of the control concrete beam. The microstructural scanning electron microscope observations confirmed that the alkali-activated fly ash increased the strength properties of the self-compacting concrete. [ABSTRACT FROM AUTHOR]

The use of aluminum alloys in automobiles is expanding, and the potential for additional increases is significant. Further growth will be determined by improvements in material qualities for existing applications or the discovery of new applications. Alloy A-356 (LM25) is commonly employed for high-quality alloy wheel rims in various motor vehicles, constituting 40% of global car usage. This study introduces 0.2% Cu into the Al–Si–Mg alloy system to enhance the mechanical properties. The alloy blend is cast into a metal mold, subjected to a 4-h cure at 540 °C, quenched with water, and precipitation hardened for 12 h at 1800 °C. Optical and scanning electron microscopes are utilized to analyze the alkali microstructure. The mechanical properties of alloyed and unalloyed castings, including hardness and tensile test results, are examined in untreated and heat-treated states. Fracture surfaces of tensile specimens are scrutinized. Intermetallic compounds formed during solidification are studied using scanning electron microscopy and x-ray diffraction analysis. The tensile strength under unalloyed (LM25) and alloyed (LM25 + 0.2 wt. % Cu) conditions before and after heat treatment [(72, 165.4 and 88.3, 237.1) and (78, 179.6 and 98, 252.9, respectively)] shows a significant increase. [ABSTRACT FROM AUTHOR]

Integrating carbon nanotubes (CNTs) into a polymer matrix can significantly modify its physical properties, providing that the challenges associated with CNT dispersion are successfully resolved. In this work, we investigate the enhancement of the dielectric properties of silicone when multiwall carbon nanotubes (MWCNTs) are introduced to its polymer matrix as a filler in the frequency range from 0.5 to 20 GHz. An optimized procedure is used to prepare nanocomposites with MWCNTs concentrations by weight of 0%, 0.5%, 1.0%, 1.5%, and 2.0%. The investigated dielectric properties for the prepared nanocomposites are the real dielectric constant ɛ′, the imaginary dielectric constant ɛ″, the loss tangent tan δ, and the AC conductivity σAC. The dispersion of the MWCNTs in the silicone matrix is confirmed using the Fourier-transform infrared (FTIR) spectroscopy and the scanning electron microscope. This study shows that the dielectric properties of the nanocomposite are enhanced as the MWCNT's concentration is increased over the entire frequency range. For example, the enhancement in ɛ′ value was from 3.2 up to 21.6 at 0.5 GHz and from 2.5 to 10.6 at 20 GHz as the concentration increased from 0% to 2.0%. For the ɛ″ value, the enhancement was from less than 0.1 to 8.6 at 0.5 GHz and to 2.0 at 20 GHz, respectively. Based on the obtained tanδ values, the nanocomposites with MWCNTs of 0.5% and 1.0% can be classified as low-loss dielectrics, while the other nanocomposites with MWCNTs of 1.5% and 2.0% are classified as lossy dielectrics. [ABSTRACT FROM AUTHOR]

The damage impact of mechanical shocks on stator bar insulation is a key factor in high-voltage motor accidents. This study conducted electrical aging acceleration and breakdown experiments on damaged stator insulating materials to understand failure causes and evaluation methods. The relationship between sample defect area and depth and electrical properties was analyzed, along with the morphology of the damaged surface using a scanning electron microscope. Results show that the defect area correlates with impact mode but does not directly impact electrical performance. Effective insulation thickness is positively linked to electrical performance. This study serves as a valuable reference for evaluating mechanical impact faults in high-voltage motors. [ABSTRACT FROM AUTHOR]

By applying ultrasonic treatment to ZL205A aluminum alloy melt containing different Cd contents and then using a tensile test, a scanning electron microscope experiment, and a metallographic experiment, the influence of ultrasonic treatment to ZL205A aluminum alloy melt on the properties of aluminum–copper alloy with different Cd contents in the liquid phase high-temperature region was studied. The effect of ultrasonic treatment on the solidification structure of ZL205A aluminum alloy was investigated. The results showed that there was no significant difference in the form of Cd and the solid solution rate of the aluminum alloy with different Cd contents in ultrasonic-assisted casting. However, the effect of ultrasonic waves on the high-temperature liquid phase of the melt of ZL205A aluminum alloy can effectively reduce the porosity defects in the solidification structure of the casting, refine the solidification structure, and make the structure more uniform. The ultrasonic cavitation effect can promote the formation and uniform distribution of Al–3Ti and improve the nucleation rate, and the effect can continue after heat treatment. This can solve the problem that increasing Cd content in ZL205A greatly reduces the toughness of castings while increasing the strength. The sample with a Cd content of 0.20% and with ultrasonic treatment has the highest strength, the average tensile strength is 475.5 MPa, and the yield strength is 381.75 MPa. However, compared with the conventional casting samples with the same Cd content, the decrease in elongation was significantly reduced. [ABSTRACT FROM AUTHOR]

In this study, basalt fibers (BFs) and nano-silica (NS) were innovatively combined to reinforce recycled aggregate concrete (RAC) to prepare recycled aggregate concrete (named NBRAC) with better mechanical and microstructural properties as an alternative to ordinary concrete. Different NBRAC specimens were prepared by adjusting the contents of NS and BF; the damage mechanism and mechanical properties of NBRAC were investigated; and the compressive, split tensile, and flexural strengths of NBRAC were evaluated. The microstructure of NBRAC was analyzed by scanning electron microscopy observation. The results showed that the densification of NBRAC was improved under the condition of 50% RA substitution rate and that its compressive, split tensile, and flexural strengths were increased by 6.8%, 16.3%, and 32.7%, respectively, compared with that of natural concrete, which proved that the method was feasible for the preparation of high-performance RAC. Scanning electron microscope image analysis confirmed the improvement effects of NS and BF on RAC, and combined with the experimental data, a composite explanation for the improvement effects of NS and BF on RAC was proposed for the first time. [ABSTRACT FROM AUTHOR]

The use of slag-based alkali-activated concrete (AAC) could effectively address the issues of resource extraction and carbon emissions caused by traditional Portland cement. In this study, the effects of the fly ash content, water–binder ratio, and alkali activation modulus on the early mechanical properties of AAC were investigated. A total of 105 cube specimens (35 sets) were designed and subjected to compressive strength tests, scanning electron microscope tests, and x-ray diffraction composition analysis. The results indicated that excellent early strength was observed in AAC, with a compressive strength reaching ∼90% of the 28th day strength before 14 days. An increase in the fly ash content and a decrease in the water–binder ratio significantly improved the compressive strength within the same age period. The impact of a lower alkaline activation modulus on strength was found to be insignificant. Based on the experimental results, a calculation method and a constitutive model for early strength were proposed, and the theoretical values exhibited a high level of agreement with the measured values. [ABSTRACT FROM AUTHOR]

Lithium batteries are promising techniques for renewable energy storage attributing to their excellent cycle performance, relatively low cost, and guaranteed safety performance. The performance of the LiFePO4 (LFP) battery directly determines the stability and safety of energy storage power station operation, and the properties of the internal electrode materials are the core and key to determine the quality of the battery. In this work, two kinds of commercial LFP batteries were studied by analyzing the electrical properties and material properties of the electrodes. After performing the rate and cycle performance tests of the battery cell, differential scanning calorimetry, scanning electron microscope, x-ray diffraction, and inductively coupled plasma were used to explore the performance of electrode materials to establish the correlation between the battery performance and the electrochemical reaction law of the internal materials and further to judge the influence of the key material properties on the battery performance. This work opens up an avenue for technical supervision of energy storage power stations. [ABSTRACT FROM AUTHOR]

To study the effect of aging on the low-temperature crack resistance of fiber asphalt mixes, three kinds of fibers (lignin fiber, polyester fiber, and basalt fiber) were dry blended into AC-13 asphalt mixes to prepare unaged, asphalt aged (that is, the original asphalt material is subjected to aging treatment), short-term aged, and long-term aged fiber reinforced asphalt mixes. Semicircular bending (SCB) tests and scanning electron microscopy tests were used to analyze and study the effects of aging time and fiber type on the low-temperature properties of asphalt mixtures at an ambient temperature of −5 °C. The SCB test results indicated that: with the deepening of aging, the fracture toughness and fracture energy of the fiber asphalt mixture specimens will tend to decrease, and the aging of the original asphalt has a greater impact on the specimens without fiber; there was great variability in the effect of lignin fibers on the crack resistance of the mix, but it could be a good promoter in unaged asphalt mixes; polyester fiber is the material of choice for improving low-temperature crack resistance in long-term aging pavements; the incorporation of basalt fiber greatly enhances the crack resistance of asphalt mixes and is an excellent material for improving aging asphalt mixes. It is clearly seen by the scanning electron microscope test that with the deepening of aging, the adhesion of asphalt and aggregate gradually deteriorates, and even more so, there is the phenomenon of fine aggregate flaking, and the fiber cannot play an excellent role in reinforcement and crack resistance. [ABSTRACT FROM AUTHOR]

Electric Field Assisted Sintering (EFAS, also referred to as spark plasma sintering) is a powerful technology for the consolidation of powder materials. The high heating rate during the sintering process is critical for minimizing energy consumption, but it can also cause microstructure heterogeneities in sintered parts, such as spatially varied porosity. The examination of localized porosity usually requires the use of a scanning electron microscope with a carefully prepared surface. In this paper, photothermal radiometry is used to measure local thermal diffusivity and extract localized porosity of EFAS-sintered parts by using a percolation-threshold model. Applying this approach, we identified the radial position-dependent porosity variation in EFAS parts, which is likely formed due to the large temperature gradient during the sintering process. This approach has a unique advantage because it can measure samples with minimal or no surface preparation, enabling the possibility of in situ characterization in EFAS with proper system modification. Necessary modifications on the measurement approach for EFAS deployment and in situ characterization are also discussed. [ABSTRACT FROM AUTHOR]

A microheater with a small temperature coefficient of resistance (TCR) at liquid hydrogen temperature was designed and fabricated by microfabrication technology. The NiCr heater annealed in N2 at 250 °C achieved the smallest TCR. The crystal structures of the NiCr film annealed in nitrogen were analyzed using a scanning electron microscope (SEM) and by x-ray diffraction (XRD). The crystallization of the NiCr film improved with the increase in annealing temperature. The failure mechanism of the microheater is studied, and it is seen that the central area of the heating film and the joint of the heating film and the electrode are most vulnerable to destruction. [ABSTRACT FROM AUTHOR]

In this study, GO/ZnO/Ag nanocomposites were prepared by a hydrothermal method in one step. The microstructure and surface morphology of the material were analyzed by x-ray diffraction and a scanning electron microscope. The chemical interactions between the available oxygen functional groups of reduced graphene oxide and the inorganic parts (Ag and ZnO) were analyzed by XPS and FTIR. The synergistic antibacterial activity of the nanocomposites against Streptococcus mutans was investigated. It was confirmed that GO/ZnO/Ag could inhibit the growth of S. mutans. The minimal inhibitory concentration and minimum bactericidal concentration of GO/ZnO/Ag on the surface structure of S. mutans were 62.5 and 125 µg/ml, respectively. The material was added to a dental dentin binder, and the modified dentin binder specimens with GO/ZnO/Ag had a significant antibacterial effect against Streptococcus mutans. The results showed that a low dose of GO/ZnO/Ag did not affect the shear bond strength of the dentin binder (P > 0.05), while a high dose of GO/ZnO/Ag decreased the shear bond strength of the dentin binder (P < 0.05). With an increase in GO/ZnO/Ag, the contact angle of the modified dentin binder specimens decreased and the hydrophilicity increased. The nanocomposites can not only be used as antibacterial agents but also have potential applications in biomedical fields. [ABSTRACT FROM AUTHOR]

We have successfully deposited a thin film of rare earth oxide on a Si substrate. After morphological characterization via a scanning electron microscope and an atomic force microscope, the electrical properties of the Al/Dy2O3/Si MOS structure were investigated using the current–voltage I(V) and capacitance–voltage C(V) measurements, as well as a study in the dynamic regime (AC) via conductance–frequency σ(f) measurements at different temperatures. Based on the classical Schottky model, we were able to determine some physical parameters, namely, the ideality factor and the potential barrier height. The effect of resistance and interface states on the current–voltage characteristics is observable and results in a deviation from the ideality factor. Then, dielectric data have been acquired by means of impedance spectroscopy over a wide frequency and temperature range. These results show that understanding the temperature dependence of the electrical characteristics of this structure may be of great help in improving the quality of Dy2O3 developed on a Si substrate for the future of device technology. [ABSTRACT FROM AUTHOR]

Surface texture has aroused widespread interest due to its role in controlling friction, reducing wear, and improving lubrication performance. As one of the most promising green processing technologies, Laser Powder Bed Fusion (LPBF) can manufacture complex structures, effectively reducing manufacturing constraints and significantly increasing structural design freedom. In this study, the powder bed model was established by numerical simulation, and the influence of different energy inputs on the morphology and characteristics of the molten pool was investigated. Based on this, the optimal forming process parameters of CuSn10 were selected. In addition, LPBF is used to process different textures (square texture, circular texture, hemispheric texture, and triangle texture) on the surface of CuSn10. The surface texture's structural accuracy, surface morphology, and wettability were studied using a profiler, scanning electron microscope, and contact angle measuring instrument, respectively. The research results show that the accuracy of the square texture structure is the closest to the original design model among all the samples and the hemispheric texture surface does not have severe powder adhesion; as a result, it has the lowest average surface roughness of 5.58 µm. However, the triangle texture has the worst formation quality. It was revealed that the stepping effect mechanism of irregularly formed surfaces is the most important reason to cause this phenomenon. In addition, the maximum contact angle of the square texture is 85.59°, which is 15.76% higher than that of the triangle texture. [ABSTRACT FROM AUTHOR]

To test the effect of pre-curing time on the impact resistance of reactive powder concrete (RPC), RPC specimens were cured in a steam curing box at a temperature of 70 °C for 72 h with pre-curing times of 18, 24, and 30 h. At 28 days, the low-speed impact test was carried out on RPC specimens with a Ceast9350 drop weight impact system at an impact rate of 5 m/s and impact energy of 140 J. The variation curves of the impact force and displacement of RPC specimens with impact times were obtained. The results show that the impact resistance of RPC specimens improved with the increased pre-curing time, implying that appropriate pre-curing time (30 h in this case) can improve RPC mechanical properties. At the same time, combined with x-ray diffraction, scanning electron microscope imaging of hydration products, and the energy dispersion spectroscopy test, the influence mechanism of pre-curing time on the impact resistance of RPC is analyzed from the microstructure standpoint. The results show that appropriate pre-curing time can make the hydration of cement form finer particles and make the hardened paste form a protective structure to reduce the damage of steam curing in the strength development process. Through multiscale homogenization calculation via the Mori–Tanaka scheme, it can be seen that RPC's stiffness increases with the prolonged pre-curing time. Optimizing pre-curing time is conducive to improving the mechanical properties of RPC specimens. [ABSTRACT FROM AUTHOR]

The electronic spins of rare-earth materials are attractive candidates for spin qubits and quantum memories. To access individual spins, tuning of the g-factor is desirable. Here, we report on local strain-dependent g-factors of the 5D0–7F2 transitions of Eu3+ centers in GaN:Eu thin films. We have found a clear correlation between the effective g-factor and the emission energy shift induced by the local strain. The combination of micro-photoluminescence and scanning electron microscope/electron backscattering diffraction measurements has revealed that the compressive strain of 0.2%–0.4%, relative to a surrounding reference point, induces an energy shift of about 3 meV. The strain decreases the g-factor of the emission at 1.991 eV from 2.5 to 1.5, while the strain increases the g-factor of the emission at 1.994 eV from 1.1 to 1.7. The result suggests that the g-factor can be tuned by the local strain. On the basis of the strain-induced energy shift and the g-factor, we have identified the optical sites. The 5D0–7F2 transitions observed in this study consist of three optical sites with C3v symmetry and one site with C1h symmetry. [ABSTRACT FROM AUTHOR]

To improve the photocatalytic activity of titanium oxide, nanometer titanium oxide powder was mixed with a phosphoric acid solution to form an electrolyte for preparing TiO2/Al2O3 coating on the surface of an aluminum alloy. Hydrothermal technology has been used to adjust the crystalline structure of nanometer titanium oxide. Scanning electron microscope was used to observe the micromorphology of anodic coating before and after treatment using hydrothermal technology. Results indicated that the photocatalyst had a porous structure. Energy dispersive spectrometry, x-ray diffraction, and x-ray photoelectron spectroscopy were used to confirm that titanium oxide was dispersed in the coating. The photocatalyst was used to degrade the methyl orange solution, and its absorbance before and after treatment by catalyst was tested by UV–vis spectroscopy. The results indicated that methyl orange could be degraded when the doping amount of titanium oxide is 8 g/l for 100 min. [ABSTRACT FROM AUTHOR]

Cu/SiO2 hybrid bonding has been developed for the application of heterogeneous bond interfaces in 3D integrated circuits in which thermal stability and bonding behavior are important. Thus, nano-twinned Cu (NT-Cu) is selected as the bonding material, and the thermal stability of NT-Cu and the bonding behavior of the interface between NT-Cu are investigated using a scanning electron microscope, electron backscatter diffraction, and focused ion beam. In addition to the microstructure analysis, nano-indentation and nano-scratch are employed to characterize the mechanical properties of the matrix and the interface between NT-Cu. As the bonding temperature increases from 200 to 300 °C for NT-Cu, the average grain sizes increase from 0.64 to 0.87 µm, and the rate of grain coarsening increases from 0.14 to 0.25 µm/h1/2. In addition, the fraction of voids at the bonding interface for NT-Cu interconnects decreases from 0.814% to 0.005%, and the penetration depth increases from 228 to 745 nm with an increase in the temperature from 200 to 300 °C. The hardness of the bonding interface obtained by nano-scratch and nano-indentation array testing is ∼1.8 GPa. [ABSTRACT FROM AUTHOR]

Investigation of the effect of crystal defects on nonpolar a-GaN films grown by metalorganic chemical vapor deposition on r-sapphire substrates is presented. Samples were grown at different temperatures and the same V/III ratio. High-temperature nucleation in combination with low-temperature GaN buffer layer growth was used to achieve a smooth morphology and "mirror" surface. The macrostructures of the defects were investigated using a scanning electron microscope. Defect concentration via dislocation type correlation was analyzed by diffractometry investigation. Structural quality was investigated via x-ray diffraction. The correlation between the densities of mixed threading dislocations and V-defects was determined. It was detected that the origin of V-defects on the a-plane and c-plane was the same despite having completely different geometries and structures. We also investigated the dependence of V-defect density on a-GaN film growth temperature at a constant hydrogen flow through a triethylgallium source, and we also investigated how the V/III ratio influenced the V-defect structure. Optimum growth parameters for defect concentration reduction were determined. [ABSTRACT FROM AUTHOR]

In this paper, the effects of three modifiers, such as PEG, ATBC, and DOP, on the modification of PBAT/PLA-based fully degradable brush monofilaments were studied. The microstructure and the mechanical properties of the PBAT/PLA brush wire before and after modification were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, and universal material testing machine. The effect of modifiers on bending recovery was discussed in detail and was analyzed combined with the results of differential scanning calorimetry and low-field nuclear magnetic resonance spectroscopy. The results showed that with an increase in the content of modifiers, the tensile strength and the impact strength of the PBAT/PLA brush wire would decrease, and the bending recovery rate would increase. The effect of PEG and ATBC on bending recovery is weaker than that of DOP, and the bending recovery rate of the PBAT/PLA brush wire modified by DOP is close to 80%. With an increase in the content of modifiers, the melting enthalpy and transverse relaxation time T2 of PBAT/PLA would increase. This research has guiding significance for the preparation of fully degradable brush wires. [ABSTRACT FROM AUTHOR]

Organic–inorganic perovskite solar cells (PSCs) have been emerging as one of the most promising photovoltaic technologies. Surface morphology is considered as a key-parameter in energy alignment and plays a dominant role in specifying the device performance. The large grains and low roughness enhance the transport of charge carriers from perovskite layers to the transport layers, and this reflects on the delivered power conversion efficiency (PCE). Therefore, in this study, we investigated the influence of the fabrication parameters on the grain size and the morphology of perovskite layers, thereby the PCE of PSCs. These parameters included the anti-solvent nature (chlorobenzene or toluene), annealing temperature, and annealing ramp rate (slow or flash annealing). The scanning electron microscope confirmed that flash annealing results in a better morphology than slow annealing whether by employing an anti-solvent dripping or not. Furthermore, the dripping of chlorobenzene as an anti-solvent produced better morphology and large grains compared with toluene. Therefore, combining chlorobenzene with flash annealing induced the formation of large grains, full cover, and a uniform perovskite layer, which reflects on the performance of the fabricated PSCs. Finally, employing the aforementioned optimum preparation parameters to fabricate carbon-based PSCs resulted in decent PCE, current density short circuit (Jsc), open circuit voltage (Voc), and fill factor (FF) of 7%, 11.3 mA/cm2, 0.74 V, and 34%, respectively. [ABSTRACT FROM AUTHOR]

To obtain the relation between spark discharges and the topography of electrode surfaces, some models, such as a micro-initial model of cone and spherical head cylinder, generated from the scanning of a scanning electron microscope are introduced. Based on the principles of energy conservation and thermal equilibrium, the second-order non-homogeneous differential equation is established. The relationships between the temperature of the cathode surface and the distance from the top of micro-protrusions, the cone angle, and the radius of the ball head are derived from a set of second-order non-homogeneous differential equations. When introduced electron emission theory, the main emission type at the initial stage of the discharge is electron field emission. As the discharge progresses, the Joule heat generated by the emission current will cause thermionic emission. During this progress, the emission current density gradually increases. When the temperature of the cathode surface reaches the melting point of the cathode metal, the current density will increase sharply. Observed from the discharge, the temperature of the cathode surface is inversely proportional to the cone angle and the radius of the ball head maintains a gradually decreasing slope. It is proportional to micro-protrusions maintaining a gradually increasing slope. When the cone angle is less than 12° and the radius of the ball head is less than 0.04 µm, the temperature of the cathode surface changes more dramatically. Through this study, a further understanding of factors that affect the density of cathode current emission can be obtained, which is of great significance to improve the capacity of cathode emission. [ABSTRACT FROM AUTHOR]

In this paper, the effect of D0 temperature, Kappa factor and the final pH value on bleaching sulfate bleached pine wood pulp was studied. The results showed that the bleaching efficiency was better when the pH value was 4, and the amount of absorbable organic halogen (AOX) in the bleaching wastewater was decreased. The Kappa factor is linear with the whiteness in the range of 0–0.15. With the increase of the Kappa factor, the amount of AOX in bleaching wastewater of D0 and Ep gradually increases. High temperature bleaching can reduce AOX production, but some fibers are hydrolyzed, leading to a decrease in pulp viscosity. The effects of chlorine dioxide solution adding sodium dihydrogen phosphate (NaH2PO4) and dimethylsulfoxide (DMSO) on pulp bleaching were investigated. The results showed that both solutions could reduce the amount of AOX in bleaching wastewater. Among them, the addition of NaH2PO4 in chlorine dioxide increased pulp whiteness, while the addition of DMSO was the opposite. Scanning electron microscope showed that a small amount of hollow cracks and more voids appeared on the surface of pulp fibers after the addition of NaH2PO4. Pulp fibers bleached by the chlorine dioxide adding DMSO have more folds and less voids on the surface. The surface wrinkles of pulp fibers increased with the addition of DMSO and the voids were less. FT-IR showed that the number of chromophore groups in the pulp bleached by chlorine dioxide adding NaH2PO4 were decreased. However, the lignin characteristic absorption peak in the pulp bleached by chlorine dioxide adding DMSO increased at the intensity of 1062 and 1160 cm−1, which indicated that there were more residual chromophore groups. [ABSTRACT FROM AUTHOR]

The structural, optical, and photocatalytic properties of TiO2 and Ag–TiO2 thin films grown by a hydrothermal method were studied by using an x-ray diffractometer, scanning electron microscope, energy-dispersive x ray, and UV–vis spectroscopy. The results indicated that all films were of single-phase and the Ag presence enhanced catalytic and water-splitting performances in the visible light region. In particular, the methylene blue solution was disintegrated up to 99% after 12 and 8 h for TiO2 and Ag–TiO2 films, respectively. Meanwhile, the splitting efficiency increased from 0.3% for TiO2 to 1% for Ag–TiO2. These performances demonstrate the great potential of Ag–TiO2 films in photocatalytic and water-splitting applications. [ABSTRACT FROM AUTHOR]

Nanoscale thermometry, an approach based on non-invasive, yet precise measurements of temperature with nanometer spatial resolution, has emerged as a very active field of research over the last few years. In transmission electron microscopy, nanoscale thermometry is particularly important during in situ experiments or to assess the effects of beam induced heating. In this article, we present a nanoscale thermometry approach based on electron energy-loss spectroscopy in a transmission electron microscope to measure locally the temperature of silicon nanoparticles using the energy shift of the plasmon resonance peak with respect to the zero-loss peak as a function of temperature. We demonstrate that using non-negative matrix factorization and curve fitting of stacked spectra, the temperature accuracy can be improved significantly over previously reported manual fitting approaches. We will discuss the necessary acquisition parameters to achieve a precision of 6 meV to determine the plasmon peak position. [ABSTRACT FROM AUTHOR]

Superhydrophobic coatings have been applied in various fields. The materials used in the preparation of superhydrophobic coatings have attracted the attention of scholars. Due to the harm of fluorine-containing substances with low surface energy to the environment, fluorine-free superhydrophobic coatings have become a hotspot in the research field. Herein, a fluorine-free superhydrophobic coating with oil/water separation was made by a solution immersion way. The fluorine-free copolymer and polydimethylsiloxane (PDMS)/SiO2 nanoparticles (NPs) were mixed to prepare a composite solution, and the superhydrophobic surface was obtained on the paper by a dipping method. The scanning electron microscope, x-ray photoelectron spectrometer, 1H nuclear magnetic resonance, and Fourier transform infrared were used to study the surface characteristics and structural composition of the superhydrophobic material. The research proved that the copolymer and PDMS/SiO2 NPs were successfully coated on the paper surface, and the rough structure of the superhydrophobic surface was also attributed to the introduction of the copolymer and PDMS/SiO2 NPs. The evaluation of the coating has proved its excellent hydrophobicity, oil/water separation performance, and self-cleaning performance. The coating is a sustainable and environmentally friendly superhydrophobic material that can be used in packaging, construction, petrochemical, and other industries. [ABSTRACT FROM AUTHOR]

In this research, we have explored the structural, morphological, electrical, and magnetic properties of Mn2+ substituted polycrystalline Ba0.4Ca0.4Sr0.2MnxTi1−xO3 (where x = 0.0, 0.05, 0.10, 0.15, and 0.20) ceramic samples prepared by the standard solid-state reaction system. The x-ray diffraction pattern of the 20% Mn-doped BCSMTO sample has confirmed a cubic to tetragonal structural phase transition. The lattice parameter is found to increase at 15% and 20% Mn concentrations, which is caused due to the inequality in ionic radii of cations. Scanning electron microscope analysis exhibited that, with the increase in Mn contents (x = 0.0–0.15), the average grain size of the samples gets bigger but then significantly decreased at 20% Mn substitution. Dielectric constants for all the samples are higher for lower frequency regions and remain independent at a higher frequency domain. The initial permeability remains almost constant at lower frequencies and then sharply falls at the cut-off frequency, which is in agreement with the Globus model. Among all the studied samples, the 10% Mn-doped ceramic sample shows the highest relative quality factor with significantly demolished loss (tan δM). At room temperature, the M–H loop for the 10% Mn-doped sample demonstrates a domination of diamagnetic nature at a higher magnetic field. The decrement in saturation magnetization with Mn addition suggests that the double-exchange interactions in tetragonal BaTiO3 may have been weakened. The outcome of this analysis emphasizes the impact of Mn as a doping element with 10% concentration in Ba0.4Ca0.4Sr0.2MnxTi1−xO3 that provides enhanced structural and electrical properties, which are associated with homogeneous grain size, reduced porosity, and lower tangent loss. [ABSTRACT FROM AUTHOR]

Supercapacitors or electrochemical capacitors are receiving greater interest because of their high-power density, long life, and low maintenance. We have synthesized CuS nanoparticles and graphene oxide (CuS–GO) nanocomposites for supercapacitor applications because of their low cost and excellent electrochemical properties. The phase purity of each material was determined using powder XRD studies. The bandgap was determined by UV-visible spectrophotometric studies. Scanning electron microscope and transmission electron microscope images revealed the nano-scale morphology of the synthesized particles. All the electrochemical measurements were conducted in a standard three-electrode configuration, using a platinum wire as the counter electrode and Hg/HgO as the reference electrode. CuS and its composites with graphene oxide on nickel foam were used as working electrodes. All the electrochemical measurements were performed in 3M KOH solution. The CuS–GO nanocomposite electrode showed a specific capacitance of 250 F/g, 225 F/g, 182 F/g, 166 F/g, 161 F/g, and 158 F/g at a current density of 0.5 A/g, 1 A/g, 5 A/g, 10 A/g, 15 A/g, and 20 A/g, respectively. CuS–GO electrodes showed a specific capacitance retention of 70% after 5000 charge–discharge cycles at a current density of 5 A/g. [ABSTRACT FROM AUTHOR]

Thin films of polycrystalline gallium antimonide (GaSb) were grown on widely available mica substrates using the physical vapor deposition method. The as-grown films contain grains of nano-scale with regular symmetries, as identified by x-ray diffraction and scanning electron microscope analysis. Two-terminal devices with coplanar electrodes were fabricated from the polycrystalline GaSb films; thus, the time dependent photoresponse property of the films was investigated by measuring the current density–voltage characteristics of devices. A significant photoresponse of the device was revealed by the linear dependence of the applied bias. Additionally, the transient behavior of the GaSb thin films was used to optimize growth temperatures of the films. This study shows that polycrystalline GaSb thin films on mica at 500 °C are suitable for high photoresponse and low noise IR photodetectors, thus proving to be a low cost solution for IR photodetectors. [ABSTRACT FROM AUTHOR]

Continuous-wave (CW) lasers are widely used in laser polishing, but with CW laser polishing, it is difficult to reduce the surface roughness to 0.2 µm from an original value exceeding 1.0 µm. The aim of this study is to develop an innovative method of laser polishing assisted by a steady magnetic field to overcome that bottleneck and produce smoother surfaces. Two experiments confirm the hypothesis that the molten pool overflows during melting peaks to flow into valleys in CW laser polishing, resulting in secondary roughness that causes the aforementioned quality bottleneck. To either reduce or eliminate this secondary roughness, a steady magnetic field is used during CW laser polishing to suppress the overflow of the molten pool. A three-dimensional surface profiler, a scanning electron microscope, and a nanometer indentation tester are used to characterize and analyze the microstructure and properties of the materials. The experimental results show that the Lorentz force due to the steady magnetic field plays an important suppression role in reducing the secondary roughness. [ABSTRACT FROM AUTHOR]

Monodispersed magnetite nanoparticles were obtained by investigating the different synthesis parameters of the solvothermal method. The morphology and chemical structure of the Fe3O4 nanoparticles were characterized by Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Dynamic Light Scattering (DLS) and Vibrating sample magnetometer (VSM). Results indicated that without the addition of water, it forms the minor phase of iron instead of magnetite. Furthermore, the size of nanoparticles is tunable in the range of 117.7 to 217.6 nm by changing the amounts of water, PSSMA and NaOH. The amount of PSSMA restricts the growth of the nanoparticles and narrow the size distribution and a hydrophilic surface was obtained. Synthesized magnetite nanoparticles were successfully conjugated with carbon dots. The resulting nanoparticles exhibited good fluorescence characteristics. Cytotoxicity tests confirmed that nanoparticles are non-toxic. Both magnetite and C-dots/Fe3O4 nanoparticles are good potential candidates for biomedical applications specifically for bioimaging and biosensing in the future. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the properties of chromium nitride (CrN) coating prepared using a high power magnetron sputtering (HiPIMS) technique. As a comparison, CrN coating prepared using a direct current magnetron sputtering (DCMS) technique is also studied. The crystal structure, surface and cross-sectional morphologies, and composite properties of the as-deposited CrN coatings are compared by x-ray diffraction, a scanning electron microscope, and a microhardness tester, respectively. It is found that the as-deposited CrN film by HiPIMS grew preferentially on (200) facet when compared with that by DCMS on (111) facet. As a result, the coatings deposited by HiPIMS have a very compact microstructure with high hardness: the microhardness reached 855.9 Hv replacing 501.5 Hv by DCMS. Besides, the inner-stress of CrN films prepared by HiPIMS is also relatively small. After measuring the corrosion resistance, the corrosion current of films prepared by HiPIMS was an order of magnitude smaller than that of CrN films deposited by DCMS. Based on the plasma diagnostics by time resolved optical emission spectroscopy, it is believed that the superior quality of CrN coatings prepared by HiPIMS is because of the ionic reaction between Cr+ and N+, rather than the neutral Cr and N reaction in DCMS during the CrN film growth. [ABSTRACT FROM AUTHOR]

A resin matrix nuclear radiation shielding material for performing in high temperature is designed and prepared, which consists of epoxy resin, elemental boron, tungsten carbide, and graphene oxide. It was manufactured under room temperature, but it can be serviced below 288 °C, and the gas production could be retained while working. The material will be applied to a land nuclear reactor, transportable nuclear reactor, or macronuclear reactor as a neutron and gamma ray shielding material. The component of the material was designed by a genetic algorithm in combination with the Monte Carlo N-Particle Transport (MCNP) software. Several blocks of the material were prepared. The TG/DTG/DSC (Thermogravimetric analysis, Derivative Thermogravimetry, and Differential Scanning Calorimeter) experiment was performed with the outgas of CO2, NH3, and H2O from the material being observed. The shielding performance of the material was examined by the MCNP software and compared with polyethylene and concrete, which, respectively, work below 90 °C and 60 °C. The scanning electron microscope experiment of the material was carried out, and the results are presented. [ABSTRACT FROM AUTHOR]

A Monte Carlo model is developed and validated to understand the ion-induced electron emission (IIEE) characteristics of complex surfaces and to show the importance of using precise geometric features to examine surface morphology effects on the yield. The decrease in IIEE from carbon velvet is accurately simulated with two distinct geometries (based on SEM images), one composed of slanted, sparsely distributed fibers and the other of tightly packed, vertical fibers. Simulation results for tungsten fuzz using a cagelike geometry predict a reduction in the yield of ∼50% compared to flat W, contradictory to previous estimates. Collisional heatmaps using the cage geometry show that the angular independence of IIEE is due to electron trapping by the horizontally oriented fibers. These insights into the emission behavior of these surfaces provide guidance for the design of new surfaces that can improve the performance of plasma devices. [ABSTRACT FROM AUTHOR]

This paper presented a morphology-selective preparation and formation mechanism of few-layer graphene (FLG) on a Cu substrate by pulsed laser ablation in liquid. It is a simple and controllable route to grow FLG directly on the surface of a copper foil at ambient temperature and normal pressure, which does not need other precursor materials. FLG with 3–10 layers of thickness and continuous hundreds of micrometers in lateral size is obtained. The morphology and structure of FLG were investigated by using a Raman spectrometer, scanning electron microscope, high-resolution transmission electron microscope, and atomic force microscope. The formation mechanism of FLG and the role of the plasma-produced carbon species are put forward based on the interaction between the laser, material, and substrate. Our finding, the direct deposition of FLG on the Cu substrate by pulsed laser ablation in liquid, will open a door to apply this green route to the production of FLG with controlled morphology. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has created the possibility of replacing traditional manufacturing techniques with faster, versatile, and cost-effective production options. In this study, we employed AM techniques to fabricate silicon carbide (SiC) radiation detectors based on commercial 4H-SiC wafers. Platinum (Pt) nanoparticle inks were synthesized and printed onto the surface of a 4H-SiC wafer using an aerosol jet printing technique to create Schottky diodes for radiation detection. The additive printed detectors were characterized for surface morphology through a scanning electron microscope (SEM) and atomic force microscope (AFM), and electronically by current-voltage (IV), capacitance-voltage (CV), and finally by alpha spectroscopy measurements. The printed detector achieved an energy resolution of 3.24% FWHM at 5.486 MeV, compared to 0.62% FWHM of a SiC detector fabricated by conventional cleanroom technologies and 0.3% FWHM of a commercially available Si detector. [ABSTRACT FROM AUTHOR]

In this work, linear isotactic polypropylene (L-PP) and long-chain branched polypropylene (LCB-PP) miscible blend, both having comparable weight average molecular weight, zero-shear viscosity, and polydispersity index, were used to produce nonwovens via melt blown technology in order to understand the role of long chain branching in the fiber diameter distribution. Basic morphological characteristics of produced nonwoven samples have been determined using digital image analysis of scanning electron microscope images considering different magnifications to capture nanofibers as well as microfibers. At the same air flow rate, polymer flow rate, and temperature, the average fiber diameters were the same, 1.6 μm, but the coefficient of variation, CV, was greater for the linear PP than for the blend. Material elasticity was assessed by reptation-mode relaxation time, λ, determined by fitting of deformation rate dependent shear viscosity by Cross and Carreau-Yasuda models as well as via fitting of frequency dependent loss and storage moduli master curve by a two-mode Maxwell model. It was found that λ is higher for LCB-PP in comparison with L-PP and the Cross model gives a meaningful relaxation time while the Carreau-Yasuda model does not despite giving a better numerical fit. Extensional rheology was assessed by the strain rate dependent uniaxial extensional viscosity (estimated from the entrance pressure drop using the Gibson method). The infinite shear to zero-shear shear viscosity ratio η∞/η0 (obtained directly from the shear viscosity data measured in a very wide shear rate range) was shown to be proportional to the maximum normalized extensional viscosity at very high extensional strain rates, ηE,∞/(3η0). η∞/η0 was related to temperature and basic molecular characteristics of given polymers via simple equation. It was observed that extensional viscosity for both samples first decreases with increased extensional strain rate to its minimum value at 200000–400000 1/s and then increases to plateau value, ηE,∞ (corresponding to the maximum chain stretch) at about 2 ⋅ 106 1/s. At low deformation rates, extensional viscosity is higher for LCB-PP in comparison with L-PP, but the trend is switched at very high deformation rates; ηE,∞ (and also ηE,∞/3η0) becomes lower for LCB-PP in comparison with L-PP. These results suggest that high stability of LCB-PP blend can be explained by its higher stretchability at very high deformation rates (occurring at the die exit where an intensive fiber attenuation takes the place) and its lower stretchability at medium and low deformation rates, at which melt/air inertia driven bending instability called whipping occurs. [ABSTRACT FROM AUTHOR]

This paper presents the strategy of selective-area growing of a positively-charged layer of Al2O3 and the negatively-charged layer of HfO2 on ion beam track-etched polyethylene terephthalate (PET) nanotubes through the thermal atomic layer deposition (T-ALD) technique. We used the self-assembled monolayer of octadecyl trichlorosilane (OTS-SAMs) on the surface to serve as a passivation layer and then selectively deposited the Al2O3 and HfO2 in the nanotubes. The influence of the dipping time of the substrates in the OTS solution and the experimental conditions on the roughness and the thickness of the OTS monolayer have been investigated. X-ray photoelectron spectroscopy (XPS) was used to analyze the composition of the ALD Al2O3 and HfO2 films. Atomic force microscope (AFM) and scanning electron microscope (SEM) were employed to study the morphologies before and after the ALD of Al2O3 and HfO2. The I-V characteristics of the film confirmed the surface charge polarities in the nanotubes, i.e. the positively-charged Al2O3 and negatively-charged HfO2, in the electrically-neutral solution. The results will aid surface modification and functionalization of PET by nanotubes. [ABSTRACT FROM AUTHOR]

Facile sol-gel synthesis method was used to prepare Selenium (Se) and Lanthanum (La) co-doped BiFeO3 nanoparticles for soft and hard ferromagnetic applications. La and Se doped bismuth ferrite nanostructures were fabricated using facile double-solvent sol-gel technique for, BiFe1-xSexO3 (BFSex) and Bi0.92La.08Fe1-xSexO3 (L8Sex), (where, x=0.1, 0.25, 0.5, 0.75, 1) nanocomposites. The structural, morphological and magnetic properties of BFSex and L8Sex were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM), respectively. Structural and morphological analysis reveals that BFSex and L8Sex transform from perovskite rhombohedral crystal structure of pure BiFeO3 to orthorhombic crystal structure by the co-substitution of Se and La. The SEM results revealed that the shape of the nanocomposites is continuously changed with increasing Se concentration starting first from nanoparticles shape to needle-like to the nanosheets and ending up to the self-growth flower-like structure under the same synthesis conditions. The magnetization of BFSex and L8Sex is large at initial Se concentration but the coercivity and squareness of the magnetic hysteresis increase with increases in Se concentration. The results revealed that various co-doped BFO novel nanostructures can be synthesized using simple and economical method for variable magnetic properties. [ABSTRACT FROM AUTHOR]

The spin Hall angle (SHA) represents the efficiency of the conversion between spin current into charge current and vice-versa. In this paper, we report the experimental detection of large enhancement of the effective SHA in heterostructures of yttrium iron garnet (YIG)/[Pt-Ag]/Pt and YIG/[Pt-Ag], when compared with measurements in YIG/Pt bilayers. The notation [Pt-Ag] represents the nanoparticles island formation of Ag in the Pt film. In order to investigate the role played by the metallic nanoparticles in the spin-to-charge conversion process, we carried out microwave spin pumping measurements in the following samples: YIG/Ag(3 nm)/Pt(6 nm), YIG/[Pt(3 nm)-Ag(3 nm)]/Pt(3 nm) and YIG/[Pt(6 nm)-Ag(3 nm)]. By means of high-resolution scanning electron microscope (HR-SEM) investigation, we confirmed that layers of Ag exhibit islands nanoparticle structures when grown on the surface of the Pt, which are characterized by the Volmer-Weber mode. The spin pumping results show that the Ag nanoparticles can enhance the charge current created by the inverse spin Hall effect (IISHE) up to three times larger than the single Pt layer. Also, by analyzing atomic force microscopy (AFM) images, obtained for samples with different thickness of the Ag layer, we conclude that the roughness plays an important role in the enhancement of the IISHE. Therefore, taking advantage of poor wetting properties of Ag over Pt layer, it was possible to create nanoscopic particles of Ag randomly grown in the Pt layer. The nanoparticles serve as nanoscopic molds to locally increase the SHA. This feature represents an improvement in searching more efficient methods of the spin-to-charge conversion and opens up the possibility of tuning the SHA by controlling the size and shape of the Ag nanoparticles. [ABSTRACT FROM AUTHOR]

The oxidation kinetics and behavior of vanadium carbide particle-reinforced Fe-based composites (VCps-Fe-MC) were investigated at 600, 800, and 950 °C. The microstructure of the surface and cross-section of the oxidation layer was characterized by scanning electron microscope (SEM). The composition of the surface of the oxide scales was examined by X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS). The micro hardness of the specimens was measured by a micro-hardness tester after a high-temperature treatment and subsequent air cooling. The results showed that the growth of the oxide scales on the VCps-Fe-MC followed a parabolic curve with an increase in the oxidation time. In addition, the weight gain increased with the oxidation temperature during the same period. Different oxide scales and oxidation rates occurred in some regions due to different textures. The minimum oxidation rate was in the austenite region because of a high silicon and chromium contents. At the same time, severe cracking and large shedding of the oxide scales were discovered due to growth stress and thermal stress. These defects can provide channels for oxygen diffusion. Based on the micro-hardness values, temperatures greater than 900 °C can be regarded as austenitizing temperatures during heat treatment to improve the mechanical properties and the wear resistance. [ABSTRACT FROM AUTHOR]

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and pentaerythritol tetranitrate (PETN), with mean sizes of 73.8 nm and 267.7 nm, respectively, were fabricated on a high-energy ball-mill. Scanning electron microscope (SEM) analysis was used to image the micron-scale morphology of nano-explosives, and the particle size distribution was calculated using the statistics of individual particle sizes obtained from the SEM images. Analyses, such as X-ray diffractometer (XRD), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS), were also used to confirm whether the crystal phase, molecular structure, and surface elements changed after a long-term milling process. The results were as expected. Thermal analysis was performed at different heating rates. Parameters, such as the activation energy (ES), activation enthalpy (ΔH≠), activation free energy (ΔG≠), activation entropy (ΔS≠), and critical temperature of thermal explosion (Tb), were calculated to determine the decomposition courses of the explosives. Moreover, the thermal decomposition mechanisms of nano CL-20 and nano PETN were investigated using thermal-infrared spectrometry online (DSC-IR) analysis, by which their gas products were also detected. The results indicated that nano CL-20 decomposed to CO2 and N2O and that nano PETN decayed to NO2, which implied a remarkable difference between the decomposition mechanisms of the two explosives. In addition, the mechanical sensitivities of CL-20 and PETN were tested, and the results revealed that nano-explosives were more insensitive than raw ones, and the possible mechanism for this was discussed. Thermal sensitivity was also investigated with a 5 s bursting point test, from which the 5 s bursting point (T5s) and the activation of the deflagration were obtained. [ABSTRACT FROM AUTHOR]

We report dielectrophoretic (DEP) assembly of biological cells and microparticles using platinum-black electrodeposited conductive textile fiber. The threedimensional conductive structures with high aspect ratios were found to facilitate high electric field regions, as revealed by scanning electron microscope characterization. The effective conducting area (Aeff) and its stability of thread electrodes were estimated using electrochemical methods. Potential of platinum black electrodeposited thread as 3-D electrodes for creating high gradient electrical field for dielectrophoretic assembly of microspheres and Saccharomyces cerevisiae (yeast cells) into 1D and two-dimensional structures over long ranges under the application of low voltages (4-10 Vpp) has been demonstrated. The formation of highly ordered pearl chains of microparticles using thread electrodes when subjected to dielectrophoresis (DEP) has been discussed in detail. [ABSTRACT FROM AUTHOR]

Temperature and frequency dependent ac electrical measurements were used to explore density of states, conduction mechanisms and dielectric properties of nickel disulfide (NiS2) nanoparticles. The NiS2 nanoparticles were prepared by conventional one step solid state reaction method at 250 °C. X-ray diffraction (XRD) confirmed cubic phase of prepared nanoparticles. Scanning electron microscope (SEM) images revealed presence of irregular shaped nanoparticles as small as 50 nm. The ac electrical measurements were carried out from 300 K to 413 K. Two depressed semicircular arcs from 20 Hz to 2 MHz showed presence of bulk and grain boundary phases in NiS2 nanoparticles at all temperatures. Small polaron hopping conduction from 300 K to 393 K and correlated barrier hopping conduction mechanism at temperatures higher than 393 K was observed. High value of density of states (of the order of 1024 eV-1cm-3) was calculated from ac conductivity. At low frequencies high values (of the order of 104-107) of real part of dielectric constant (ε') were observed at different temperatures. These observations suggest that NiS2 nanoparticles may find applications in electronic devices. [ABSTRACT FROM AUTHOR]

We demonstrate a random lasing emission based on microporous surface of Cr2+: ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10-4 Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ~13 μm and smaller ones with ~1.2 μm on the surface of Cr2+: ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr2+:ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr2+:ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength. [ABSTRACT FROM AUTHOR]

Femtosecond laser processing is emerged as a promising tool to functionalize surfaces of various materials, including metals, semiconductors, and polymers. However, the productivity of this technique is limited by the low efficiency of laser raster scanning. Here we report a facile approach for efficiently producing large-area functional polymer surfaces, by which metal is firstly textured by a femtosecond laser, and the as-prepared hierarchical structures are subsequently transferred onto polydimethylsiloxane (PDMS) surfaces. Aluminum pieces covered by laser induced micro/nano-structures act as template masters and their performance of displaying diverse colors are investigated. Polymer replicas are endowed with tunable wetting properties, which are mainly attributed to the multi-scale surface structures. Furthermore, the surfaces are found to have extremely high adhesive force for water drops because of the high water penetration depth and the resultant high contact angle hysteresis. This characteristic facilitates many potential applications like loss-free tiny water droplets transportation. The reusability of metal master and easiness of soft lithography make it to be a very simple, fast and cost-efficient way for mass production of functional polymeric surfaces. [ABSTRACT FROM AUTHOR]

The flower-like SnO2 particles are synthesized through a simple hydrothermal process. The microstructure, morphology and the infrared emissivity property of the as-prepared products are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and infrared spectroradio meter (ISM) respectively. The results show that the as-prepared SnO2 products are all indexed to tetragonal cassiterite phase of SnO2. The different molarity ratios of the OH- concentration to Sn4+ concentration ([OH-]:[Sn4+]) and the polyacrylamide (PAM) lead to the different morphological structures of SnO2, which indicates that both the [OH-]:[Sn4+] and the PAM play an important role in the morphological evolution respectively. The infrared emissivities of the as-prepared SnO2 products are discussed. [ABSTRACT FROM AUTHOR]

It is of great benefit to study the material and structural heterogeneity of coal for better understanding the coalbed methane (CBM) storage and enrichment. In this paper, multi-scale X-ray computed tomography (CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) at multi scales were conducted to thoroughly study the material distribution, heterogeneity, pore development, porosity and permeability of coal. It is suitable and reasonable to divide the testing samples into three structural categories by average density and heterogeneity degree, and the meso structure in the three categories accords with the morphology on SEM images. The pore size distribution and pore development of each subsample cannot be correspondingly related to their respective structure category or morphology due to different observation scales, while the macro pore size development, accumulated macro pore volume and macro pores porosity accord with the meso structure category and morphology information by CT and SEM at the same scale very well. Given the effect of macro pores on permeability and the contribution of micro pores to CBM storage capacity, reservoirs with developed micro pores and macro pores may be the most suitable coal reservoir for CBM exploitation. [ABSTRACT FROM AUTHOR]

Defocus and astigmatism can lead to blurred images and poor resolution. This paper presents a simplified method for focusing and astigmatism correction of a scanning electron microscope (SEM). The method consists of two steps. In the first step, the fast Fourier transform (FFT) of the SEM image is performed and the FFT is subsequently processed with a threshold to achieve a suitable result. In the second step, the threshold FFT is used for ellipse fitting to determine the presence of defocus and astigmatism. The proposed method clearly provides the relationships between the defocus, the astigmatism and the direction of stretching of the FFT, and it can determine the astigmatism in a single image. Experimental studies are conducted to demonstrate the validity of the proposed method. [ABSTRACT FROM AUTHOR]

The vertical aligned carbon nanotubes (CNTs)-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si) wafer substrate at 775 °C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness) as a barrier layer and iron (Fe, 1.5 nm thickness) as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM) images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2–30 walls with an inner diameter of 3–8 nm. Raman spectrum analysis shows G-band at 1580 cm−1 and D-band at 1340 cm−1. The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm2 at 1.2V/μm), low turn-on field (0.6 V/μm) and field enhancement factor (6917) with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron sources. [ABSTRACT FROM AUTHOR]