Scanning Electron Microscopy Technology Research Articles

Mechanical behaviour of weakly filled granite and a unified evaluation method for macro-fine-micro multi-scale fracture characteristics

The mechanical properties of weakly filled rock are critical for engineering rock stability control. With the help of 3D DIC (Digital Image Correlation) and AE (Acoustic Emission) monitoring system, and the industrial CT (Computed Tomography), 3D laser scanning and SEM (Scanning Electron Microscope) technology, the mechanical behaviour and fracture characteristics of granite with different inclination angles of planar weak filling were analyzed comprehensively. Firstly, the influence law of the inclination angle of planar weak filling on the basic mechanical properties of the specimens was investigated, and it was confirmed that the specific angle had an obvious weakening effect on the specimen’s ability to resist deformation. Then, the spatial deformation field evolution and failure mode of the specimen were analysed, and it was found that when the inclination angle increased from 0° to 90°, the failure mode of the specimen will gradually change from “Y”-shaped shearing and splitting mixed failure to “chain” splitting failure, and then to overall splitting failure. Then, the spatial distribution of the micro-fracture event was analysed, and the results show that the spatio-temporal evolution and distribution characteristics of the micro-fracture events, the distribution characteristics of the spatio-temporal evolutionary local enlargement zone of the deformation field and the spatial distribution of the main fracture surface at the time of final failure are highly consistent and correlated. The spatio-temporal evolution and distribution characteristics of micro-fracture events provide important references for predicting the location, time and degree of spatial failure in weakly filled rock mass. Finally, based on the fractal theory, the fracture characteristics within the multiscale of the specimen were analysed, and the method of evaluating the unity of the multiscale fracture characteristics of the rock mass was summarised and given.

Research on the Compression Performance and Damage Mechanism of Larix Wood With Smooth Grain

In order to investigate the compression performance and damage mechanism of fallen wood in the down-grain direction, northeast larix was taken as the research object. Through the monotonic compression test of 12 specimens, the deformation characteristics, damage mode, and stress-strain curve properties of larix wood under compression in the direction of the smooth grain were analyzed; scanning electron microscope technology was used to analyze the damage and fracture characteristics of wood fibers from the microscopic point of view to further reveal the damage mechanism of wood monotonic compression. The results showed that larix wood compressed in the paragons produced three damage modes of end collapse, shear damage and paragons splitting after the peak load, and the shear damage usually occurred at the junction of the early and late wood tubular cells due to the difference between the early and late wood tubular cells. On this basis, an isomorphic model was established to describe the compression of larix wood in the smooth grain.

Macro-micro exploration on dynamic interaction between aflatoxigenic Aspergillus flavus and maize kernels using Vis/NIR hyperspectral imaging and SEM technology

Aspergillus flavus and its toxic metabolites-aflatoxins infect and contaminate maize kernels, posing a threat to grain safety and human health. Due to the complexity of microbial growth and metabolic processes, dynamic mechanisms among fungal growth, nutrient depletion of maize kernels and aflatoxin production is still unclear. In this study, visible/near infrared (Vis/NIR) hyperspectral imaging (HSI) combined with the scanning electron microscope (SEM) was used to elucidate the critical organismal interaction at kernel (macro-) and microscopic levels. As kernel damage is the main entrance for fungal invasion, maize kernels with gradually aggravated damages from intact to pierced to halved kernels with A. flavus were cultured for 0–120 h. The spectral fingerprints of the A. flavus-maize kernel complex over time were analyzed with principal components analysis (PCA) of hyperspectral images, where the pseudo-color score maps and the loading plots of the first three PCs were used to investigate the dynamic process of fungal infection and to capture the subtle changes in the complex with different hardness of the maize matrix. The dynamic growth process of A. flavus and the interactions of fungus-maize complexes were explained on a microscopic level using SEM. Specifically, fungus morphology, e.g., hyphae, conidia, and conidiophore (stipe) was accurately captured on the microscopic level, and the interaction process between A. flavus and nutrient loss from the maize kernel tissues (i.e., embryo, and endosperm) was described. Furthermore, the growth stage discrimination models based on PLSDA with the results of CCRC = 100 %, CCRV = 97 %, CCRIV = 93 %, and the prediction models of AFB1 based on PLSR with satisfactory performance (R2C = 0.96, R2V = 0.95, R2IV = 0.93 and RPD = 3.58) were both achieved. In conclusion, the results from both macro-level (Vis/NIR-HSI) and micro-level (SEM) assessments revealed the dynamic organismal interactions in A. flavus-maize kernel complex, and the detailed data could be used for modeling, and quantitative prediction of aflatoxin, which would establish a theoretical foundation for the early detection of fungal or toxin contaminated grains to ensure food security.

Pore development characteristics and controlling factors of Lower Cambrian Qiongzhusi shale gas reservoir in Sichuan Basin, China

Recently, the shale gas exploration of Lower Cambrian Qiongzhusi Formation in Sichuan Basin has made a great breakthrough. However, the pore characteristics and controlling factors of the shale-gas reservoir in the Qiongzhusi Formation are not clear, which hinders further exploration and development of shale gas. This paper focuses on the Qiongzhusi Formation in the Lower Cambrian of the Sichuan Basin. On the basis of mineral composition and the lithofacies types of shale-gas reservoirs in Qiongzhusi Formation were classified by microscopic observation. Additionally, focused ion beam-scanning electron microscope (FIB-SEM), advanced mineral identification and characterization system (AMICS) analysis, large-field stitching scanning electron microscope technology (MAPS) and nitrogen adsorption experiment were employed to comprehensively determine the differential characteristics and controlling factors of pore development. The results indicate that the pore types in Qiongzhusi Formation are mainly composed of interparticle pores and intercrystalline pores. The pore structure of Qiongzhusi Formation is complex. Significant differences in pore structure parameters are observed among different lithofacies. Quartz and feldspar contribute to the preservation of primary pores due to their strong compressive resistance. Clay minerals and carbonate minerals impede pore development by occluding pores. The influence of organic matter on the pore development is relatively small. According to the mineral composition and pore parameters, laminated shale is a relatively favorable reservoir facies among different lithofacies types.

Development and performance evaluation of alkali-activated multiple solid waste-based building foam insulation materials

To reduce building environmental pollution and energy consumption has become the mainstream development trend of today’s society. The building foam insulation materials (SWFIM) was developed by using blast furnace slag (BSF), waste photovoltaic glass (WPG), rice husk ash (RHA), and plant ash (PA), and the corresponding preparation technologies were proposed. The dry density, thermal conductivity, compressive strength, volumetric water absorption and pore structure parameters of SWFIM were measured. The effects of the amount of hydrogen peroxide solution (HPS), foam stabilizer (FS) and polyethylene (PE) fiber on the basic properties of SWFIM were discussed. The microscopic morphology of SWFIM was characterized by SEM (Scanning electron microscope) technology, and the mechanism of three influencing factors were revealed. The relationship between the basic properties of SWFIM was discussed and the corresponding prediction models were established. The test results showed that the effects of HPS and FS on the basic properties of SWFIM were complementary. When the amount of HPS and FS was 10 % and 1 %, respectively, SWFIM have achieved encouraging performance. PE fiber had different degrees of negative effects on the thermal properties of SWFIM, and the negative effects gradually increased with the increase of PE fiber content. The improvement effect of PE fiber on the compressive strength of SWFIM changes from positive influence to negative influence with the fiber content. When the fiber content increased to 0.6 %, the improvement effect was most obvious, increased by about 12.20 %. Statistics showed that the thermal conductivity and compressive strength of SWFIM were 0.0497 ∼ 0.0581 W/(m·K) and 0.33 ∼ 0.52 MPa, respectively. This showed that SWFIM was expected to become a potentially competitive building insulation material.

Wear mechanism and leakage failure analysis of the mechanical seal end face of an oil transfer pump

The John Crane 48 V mechanical seal is a long-distance oil transfer pump station shaft end seal; its sealing effect directly affects pipeline production safety. However, it has been found that there is oil leakage at the shaft end of the pump station. In order to explore the oil transfer pump mechanical seal abnormal leakage failure causes, to ensure the safety and stability of production, the end face of the 48 V mechanical seal was analyzed by white light interference and scanning electron microscope technology. The failure mechanism of the 48 V mechanical seal was explored from the perspective of the wear mechanism of moving and stationary rings. Results showed that the wear mechanism of the 48 V mechanical seal stationary ring was mainly abrasive wear, and substantial furrows, bulges, and depressions existed on the wear surface. The material removal mechanism was brittle spalling, and the roughness of the wear surface increased with the increase in wear depth and decreased with the increase in wear average width. Uneven wear occurred on the end face of the stationary ring of the mechanical seal, resulting in the leakage of the sealing medium from the end cover of the mechanical seal. The working condition could be improved by adding a spring compensation device to the stationary ring or increasing the gap between the stationary ring and the shaft sleeve.

The crack-healing and strength recovery mechanisms for the new developed Ti(C,N)-TiSi2-WC composite ceramic tool materials with crack-healing ability

Because the ceramic tool life will be reduced due to the crack growth, it is necessary to develop the new ceramic tools with crack-healing ability for improving the ceramic tool life. Ti(C,N)-TiSi2-WC composite ceramic tools were fabricated by vacuum hot pressing sintering technology. The Vickers hardness tester was used to prefabricate cracks with different lengths. The crack-healing abilities of materials were researched by air and vacuum heat treatments. The effects of different healing conditions on crack-healing behaviors were investigated based on the strength recovery and microstructure of crack morphology. The healing conditions included healing temperature, healing time, crack length and healing atmosphere. It could be found that the surface cracks were entirely healed after air heat treatment, but locally healed after vacuum heat treatment. After air heating at 800 °C for 90 min, the restoration ratio of flexural strength of the crack-healed samples returned to 109.02% compared to that of the smooth specimen. The strength of the crack-healed specimen would be fully recovered when the crack length was less than 400 μm. After vacuum heating at 1000 °C for 60 min, the recovery of the flexural strength of the crack-healed samples returned to 49.73%. X-ray diffraction and scanning electron microscope technology were used to analyze compositions and microstructure of crack-healed specimens. In the air atmosphere, the liquid filling of SiO2 and TiO2 and crack closure caused by WSi2 and MoSi2 were confirmed as the crack-healing mechanisms. SiO2 and TiO2 were produced by high temperature oxidation reaction of TiSi2 and WSi2. WiS2 and MoSi2 were new phases formed during sintering and heat treatment, and their formation could be explained by thermodynamically feasible reactions. In the vacuum atmosphere, local filling of the crack with silicide solid solutions such as WSi2, MoSi2 and NiSi was the main crack-healing mechanism.

Dynamic tensile properties of carbon/glass hybrid fibre composites under intermediate strain rates via DIC and SEM technology

Carbon/glass hybrid fibre-reinforced plastic (C/GFRP) can effectively reduce product costs in manufacturing; however, its dynamic tensile properties remain unclear. In this study, the mechanical characteristics of C/GFRP and glass-fibre-reinforced plastic (GFRP) laminates were investigated using an HTM5020 high-speed tensile tester, digital image correlation (DIC), and scanning electron microscopy (SEM) at intermediate strain rates. Six strain rates (1, 10, 100, 250, 500 and 800 s−1) followed by three stacking sequences ([C2,G3,C2]s, [G3,C2,G3]s and [G8]s) were developed. The failure mechanism of C/GFRP under intermediate strain rates was identified using stress–strain curves, DIC sub-images, and macro/micro failure modes. Additionally, the variation laws for fracture strain, elastic modulus, and dynamic tensile strength of C/GFRP were examined. In response to an increase in strain rate, the strength and fracture strain of [C2,G3,C2]s increased by 36.6% and 142.9%. The elastic modulus [G3,C2,G3]s increased by 41.8%. Hybrid laminates are prone to interlaminar failure, resulting in lower strength and higher strain-rate sensitivity. Adding a carbon fibre-reinforced plastic layer effectively improves the stiffness of the laminates. A stiffness prediction formula for C/GFRP is proposed.

Experimental Study on Mechanical Properties of Polyurethane Cement Composite (PUC) Under Various Temperatures

This paper aims to investigate the mechanical properties of polyurethane cement (different ratios) at different ambient temperatures. The temperature and proportion which affect the constitutive relation of the material were analyzed by axial tensile test. The microstructure and failure mode of polyurethane cement were studied using scanning electron microscope technology. At -40oC ~40oC, the stress-strain curves of polyurethane cement with different proportions were roughly similar. When the temperature was higher than 40oC, with the rise of temperature, the ultimate tensile strength of polyurethane cement specimens would decrease but the ultimate strain would increase. When the temperature was lower than -40oC, with the decline of temperature, the ultimate strain and tensile strength of polyurethane cement specimens would decrease. The ultimate stress of polyurethane cement with different ratios was different. With the rise of the proportion of polyurethane components, the ultimate stress would increase but the elastic modulus would decrease. Macroscopically, the failure modes of polyurethane specimens were different with the change of temperature. Brittle fracture occurred at low temperatures. At high temperatures, the specimen did not fracture, but a large number of �V�shaped cracks appeared at the edge. The higher the temperature, the more obvious this phenomenon was. At the microscopic level, the fibers didn t break at high temperatures, and there were obvious cracks and more stubble on the surface of cracks at room temperature.

Quantitative Characterization of Pore Structure Parameters in Coal Based on Image Processing and SEM Technology

The pore structure parameters of coal have an important influence on the exploration and development of coalbed methane. In this study, a series of pore structure parameters, including porosity, pore radius, pore throat radius, pore coordination number, pore throat ratio, and specific surface area, are identified, extracted, and calculated in the scanning electron microscopy (SEM) images of coal reservoir samples using algorithms and application programs in MATLAB. Constant rate-controlled mercury injection and low-temperature N2 adsorption experiments were carried out to determine the accuracy of the SEM image-based processing analysis results. Characterization results show that the distribution of pore radius in the target coal samples of different organic matters range from 15 nm to 500 μm with porosity of 1.87–8.31% and radius distribution of 12.7 nm to ~100 μm. A noise-reduction system was constructed to eliminate the optical noise of non-porous features and repair the space affected by binarization noise. It is suggested that the characterization processing in this study is suitable for coal or other organic-rich porous materials with porosity > 2% and pore radius > 15 nm.

Time series analysis of tegument ultrastructure of in vitro transformed miracidium to mother sporocyst of the human parasite Schistosoma mansoni

The transformation of Schistosoma mansoni miracidia into mother sporocysts is induced, either in vivo by the penetration of the free-living larval stage, the miracidium, in the snail Biomphalaria glabrata or in vitro following the incubation of the miracidium in Chernin's Balanced Salt Solution (CBSS) or Bge (B. glabrata embryonic cell line) culture medium. The in vitro development of S. mansoni miracidium into mother sporocyst was monitored by Scanning Electron Microscopy (SEM) from 2.5 h to 120 h in CBSS. The transformation starts when the miracidium ciliate plates detach due to the proliferation of the intercellular ridge associated with the degeneration of mid-body papillae of the miracidium. The loss of ciliated plates causes the appearing of scars, filled across time by the proliferation of a new tegument originating from the interplate ridge. This new tegument covers the entire body of the metamorphosing parasite and differentiates over time, allowing some exchanges (uptakes or secretion/excretion) between the parasite and its host. In contrast to the well-described development of adult and free-living larval stages of S. mansoni using SEM, the developmental transformation of intramolluscan stages, especially tegumental changes in the mother sporocyst, has been sparcely documented at the ultrastructural level. In addition, taking into account the latest literature on miracidium electron microscopy and the advances in SEM technologies over the last thirty years, the present study gathers three main objectives: (i) Fill the gap of tegument scanning electron micrographs of in vitro transforming sporocysts; (ii) Update the current bibliographic miracidia and sporocysts image bank due to rapid evolution of SEM technology; (iii) Understand and describe the critical steps and duration of the in vitro miracidium-to-sporocyst transformation process to assist in understanding the interaction between the larval surface and snail immune factors.

Experimental investigation of rotary ultrasonic face milling on red granite: A comparison with conventional grinding

Long-term sustainability with cost-effective machining and materials are used in many companies these days. Also, precise machining on brittle and hard materials is becoming a challenge for production engineering. Rotary ultrasonic face milling (RUFM) is an unconventional milling process that is preferred to perform precise surface machining on such materials. The research work aims to analyse the enhancement in conventional diamond grinding (CG) due to the addition of ultrasonic vibration and compare both processes (RUFM and CG). Analysis of variance (ANOVA) technology was applied for the analysis. The scanning electron microscopy (SEM) technique was used to analyse the tool wear after milling operation. The controlling factors used for the study were feed rate, depth of cut, and ultrasonic power. The outcomes of the study showed an increment in material removal rate during RUFM compared to CG. Material removal rate (MRR) also increases with increment in each level of controlling factors. Surface roughness (SR) increases with the addition of ultrasonic vibration during RUFM. Also, SEM technology shows the complete removal of diamond grits at the bottom surface of the tool. The research concluded that tool life and material removal rate get improved but the reduction in surface finish during RUFM while comparing to CG.

Morphological features and fractography analysis for in situ spalling in the China Jinping underground laboratory with a 2400 m burial depth

Brittle spalling of hard rock is a typical failure in deep underground engineering that induces challenges for construction safety. Seventy marble spalling samples were collected from the China Jinping Underground Laboratory Phase-II (CJPL-II) to analyse their mesoscopic morphology and failure mechanism. The 3D scanning and corresponding statistical analysis indicated that the spalling surfaces were not smooth but with low roughness and evident anisotropy, and that the morphological transition (i.e. from the mirror zone to the mist zone then to the hackle zone) on the spalling surface was observed. The fractography of the CJPL-II spalling samples showed typical features of brittle fracture dominated by the granular morphology of intergranular fracture based on the Scanning Electron Microscope technology. What’s more, the simulated spalling by the laboratorial true triaxial unloading tests showed similar morphology with that of CJPL-II spalling. Moreover, by comparing the marble spalling samples with other granite spalling and basalt sapling samples, the effect of the mineral particle size of the surrounding rock on the roughness of the spalling slice was discussed. This study deepens the understanding of the in-situ spalling mechanism of hard rock under high geostress conditions.

3D Reconstruction and Analysis of Thin Subcellular Neuronal Structures using Focused-Ion Beam Scanning Electron Microscopy Data.

Recent advances in scanning electron microscope technologies now permit the rapid three-dimensional (3D) analysis of ultrathin subcellular processes. Here, a methodological pipeline is presented to identify, visualize, and analyze thin neuronal processes, such as those that project into the presynaptic boutons of other neurons (termed 'spinules'). Using freely available software packages, this protocol demonstrates how to use a decision tree to identify common neuronal subcellular structures using morphological criteria within focused ion beam scanning electron microscopy (FIB-SEM) image volumes, with particular attention on identifying a diversity of spinules projecting into presynaptic boutons. In particular, this protocol describes how to trace spinules within neuronal synapses to produce 3D reconstructions of these thin subcellular projections, their parent neurites, and postsynaptic partners. Additionally, the protocol includes a list of freely available open-source software programs for analyzing FIB-SEM data and offers tips (e.g., smoothing, lighting) toward improving 3D reconstructions for visualization and publication. This adaptable protocol offers an entry point into the rapid nanoscale analysis of subcellular structures within FIB-SEM image volumes.

Northwest Siberia as a MIS 2 desert? Inferences from quartz morphoscopy and polygonal ice wedges

Following a major revision of the Sartan ice sheet limits, Velichko et al.’s (2011) view of northwestern Siberia as a cold arid desert during MIS 2 (27.8–11.7 ka) has been prominent in regional scholarship. Our article presents the analysis of a series of sandy sediments associated with MIS 2 polygonal ice-wedge pseudomorphs (PIWPs) located in the Lower Nadym, the Middle Nadym, and the Siberian Uvals regions. Whereas Velichko et al.’s cold desert hypothesis was based on optical morphoscopy, our research relied on the scanning electron microscope technology (in conjunction with sedimentological, soils, and radiocarbon data). Our morphoscopic analysis of three wedge fill – host sediment pairs suggests that none of the MIS 2 surface sediments can be unequivocally associated with desert dune environments, but instead resemble alluvial deposits that have been moderately to substantially reworked by aeolian and cryogenic (freeze-thaw) processes. While the environmental characteristics varied between different sub-regions, northwestern Siberia likely resembled a sparsely vegetated tundra during MIS 2. AMS radiocarbon dates obtained from the organic matter of paleosols discovered inside of PIWPs indicate that the climate warming in northwestern Siberia began around 13.5–13 ka cal BP (end of MIS 2). This climatic shift was associated with a more pronounced warm season, as evidenced by the surface sediments experiencing more intensified freeze-thaw cycles in all of the examined locations. Judging from our analysis of sandy deposits, aeolian activity intensified in the Siberian Uvals in the middle MIS 2, compared to early MIS 2. Aeolian activity also intensified in the Middle Nadym in the second part of MIS 2, compared to the first part of MIS 2. Besides the intensified freeze-thaw processes at the end of MIS 2, surface deposits of the Lower Nadym region remained relatively stable throughout the Sartan cryochron.

Attenuation and Absorption of Electromagnetic Waves of Nanocomposites (ZnFe2O3 / Graphene: UPE) by Wave Guide Technical

In this article, composites with a polymeric basis were prepared and developed with a ZnFe2O3 material dyed with graphene that has the ability to absorb and attenuate by a weight ratio of (1-4) % of the base. The samples were formed by chemical blending and ultrasound technology to homogenize the mixture. The waveguide technique was used at the microwave frequencies in the range of 8- 12 kHz and within the X-band range - the results showed a significant improvement in the absorbance and attenuation by increasing the percentage of the deformed material compared to the blank material, and the best value was obtained at 3%. The compositional examinations of the Nano powder were performed using a scanning electron microscope technology equipped with an EDX scan.

Direct Observation Techniques Using Scanning Electron Microscope for Hydrothermally Synthesized Nanocrystals and Nanoclusters

Metal oxide nanocrystals have garnered significant attention owing to their unique properties, including luminescence, ferroelectricity, and catalytic activity. Among the various synthetic methods, hydrothermal synthesis is a promising method for synthesizing metal oxide nanocrystals and nanoclusters. Because the shape and surface structure of the nanocrystals largely affect their properties, their analytical methods should be developed. Further, the arrangement of nanocrystals should be studied because the properties of nanoclusters largely depend on the arrangement of the primary nanocrystals. However, the analysis of nanocrystals and nanoclusters remains difficult because of their sizes. Conventionally, transmission electron microscopy (TEM) is widely used to study materials in nanoscale. However, TEM images are obtained as the projection of three-dimensional structures, and it is difficult to observe the surface structures and the arrangement of nanocrystals using TEM. On the other hand, scanning electron microscopy (SEM) relies on the signals from the surface of the samples. Therefore, SEM can visualize the surface structures of samples. Previously, the spatial resolution of SEM was not enough to observe nanoparticles and nanomaterials with sizes of between 10 and 50 nm. However, recent developments, including the low-landing electron-energy method, improved the spatial resolution of SEM, which allows us to observe fine details of the nanocluster surface directory. Additionally, improved detectors allow us to visualize the elemental mapping of materials even at low voltage with high solid angle. Further, the use of a liquid sample holder even enabled the observation of nanocrystals in water. In this paper, we discuss the development of SEM and related observation technologies through the observation of hydrothermally prepared nanocrystals and nanoclusters.

V2O3@Amorphous Carbon as a Cathode of Zinc Ion Batteries with High Stability and Long Cycling Life

Zinc ion batteries (ZIBs) have the advantages of environmental friendliness, safety, and simple assembly and have strong application potential in the field of energy storage. In this work, an amorphous carbon-loaded V₂O₃ (V₂O₃@AC) material is prepared by calcination and used as a cathode material for ZIBs. The V₂O₃@AC cathode has excellent stability and long life, which maintains 94.8 and 90.7% capacity retention after 180 cycles at 0.1 A g–¹ and after 1600 cycles at 1 A g–¹, respectively. By scanning electron microscopy (SEM) characterization, V₂O₃@AC is composed of small irregular nanoparticles, which have a lot of space for electrolyte penetration and ion transmission, and the kinetic studies also confirm this transport capability. The mechanism of zinc storage is studied by ex situ X-ray powder diffraction, X-ray photoelectron spectroscopy, and SEM technology, and they confirm that V₂O₃ will undergo phase transition and become V₁₀O₂₄·12H₂O during the first charge process. Due to the high stability and cycle life of V₂O₃, we believe that it has competitive potential in zinc ion batteries and can play an important role in large-scale energy storage in the future.

Influence of the physical properties of pumice and biochar amendments on the soil’s mobile and immobile water: implications for use in saline environments

Context Biochar and pumice have potential to improve soil water retention and mitigate salinity. However, little is known about their effect on salt transport in sandy soils. Aims We investigated the influence of the porosity and pore size distribution of soil amendments with pumice and biochar on the mobile water content of a New Zealand sandy soil. Methods Pumice and biochar (1.5-cm, 3-cm and 6-cm in diameter, Ø) were characterised using scanning electron microscope technology. The fraction of mobile water present in these amendments, previously added to a sandy soil at different application rates and particle sizes, was determined using a tracer (Na+) technique. Key results (1) Pumice exhibited a wider pore-size span than biochar; and (2) both materials had a predominance of pores with Ø < 30 μm; but (3) the total porosity in pumice and biochar was not significantly different; (4) pumice had a significantly larger (P < 0.05) mean absolute micro-scale porosity than biochar; and (5) a significantly greater (P < 0.05) relative resident Na+ concentration than biochar, irrespective of the particle size. Conclusions These results reflect a larger fraction of the mobile water in pumice than that of biochar under near-saturated conditions, irrespective of the biochar particle size; and this increased as the pumice particle size increased. Implications While both materials are expected to contribute to water retention and thus might alleviate salt-stress by diluting salt concentration, pumice may perform better than this specific biochar on improving the retention of plant-available water.

Synthesize and characterize of Fe3O4/zeolite 4A magnetic nanocomposite

In order to solve the problem that separating zeolite 4A from solutions, we have synthesized Fe3O4/zeolite 4A magnetic nanocomposite by hydrothermal method. It is characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), Vibrating Sample Magnetometer (VSM), scanning electron microscope (SEM) and Brunner-Emmet-teller (BET). The XRD result shows that Fe3O4/zeolite 4A magnetic nanocomposite has a good crystal structure. It also shows that Fe3O4/zeolite 4A magnetic nanocomposite contains two phases of zeolite 4A and Fe3O4 MNP. The optimal sample (Z-2) was judged by the calculation of crystallinity. The successful combination of zeolite 4A and Fe3O4 MNP was visually observed through SEM technology. The functional groups of Fe3O4/zeolite 4A magnetic nanocomposite were characterized by FTIR technology. The TEM result shows that some Fe3O4 MNPs enter zeolite 4A, which further clarifies the microstructure of Fe3O4/zeolite 4A magnetic nanocomposite. N2 adsorption-desorption technique confirms that Fe3O4/zeolite 4A magnetic nanocomposite SBET is 55.3374 m2/g and Dave is 9.7128 nm. VSM result shows that Fe3O4/zeolite 4A magnetic nanocomposite magnetization is 18.4534 emu/g. Simulation experiment shows that Fe3O4/zeolite 4A magnetic nanocomposite exhibit a fast response to an external magnetic field.