Search

To study the mechanical properties of red clay under repeated dry and wet cycle test conditions, in this paper, the disturbed red clay in an engineering area in Liuzhou, Guangxi Province, was taken as the research object. By artificially controlling different dry and wet cycles in the laboratory, a direct shear test and triaxial consolidation drainage test were carried out on the red clay samples after different dry and wet cycles. The stress-strain curve and change rule of corresponding c and φ values were obtained. The results showed that, in both the direct shear test and the triaxial test, the shear strength parameters of red clay decreased with an increase in the number of dry and wet cycles and the attenuation was most obvious during the first cycle. With an increase in the number of dry and wet cycles, the attenuation gradually decreased. The constitutive model of the deviatoric stress and strain curve of red clay under dry and wet cycles was a plastic-hardening type. By analyzing the variation in parameters in the P-H model, the relationship between c, φ, and the number of dry and wet cycles n was obtained. The results showed that the parameters had different degrees of attenuation with the action of dry and wet cycles. To explain the above rules, some samples under different drying-wetting cycles were selected for environmental electron microscope scanning, and appropriate assumptions were made based on the microstructure. [ABSTRACT FROM AUTHOR]

Summary: We studied Na0.8Ni0.33Co0.33Mn0.33O2 nanoparticles synthesized using water‐based extract procured from the dried silk of maize (Zea mays lea) plant. The synthesized Na0.8Ni0.33Co0.33Mn0.33O2 was used as the positive electrode in an aqueous sodium ion battery (SIB). X‐ray diffraction (XRD) studies of the biosynthesized material reveal that it can be indexed to the trigonal structure of Na0.8Ni 0.33Co0.33Mn0.33O2 with an R 3m space group (160), (ICSD 184736) although impurities of Mn2O3 and NiO were detected. Surface morphological studies from a scanning electron microscope (SEM) disclose that the nanoparticles consist of an interspersion of sheath‐like particles with quasi‐spherical nanoparticles of uneven dimensions. The sheath‐like particles seem to agglomerate to form layers that coalesce into flower‐like structures that are spread within the quasi‐spherical nanoparticles. The material yielded a rechargeable discharge capacity of about 86 mA h g−1 in a three‐electrode system consisting of platinum, the Na0.8Ni0.33Co0.33Mn0.33O2 and Ag/AgCl as the counter, working and reference electrodes respectively at a current density of 10 mA g−1. However, a full cell using P25 Degussa TiO2 and the biosynthesized Na0.8Ni0.33Co0.33Mn0.33O2 as the negative and the positive electrode, respectively, and having a mass ratio of 1:1 yielded a discharge capacity of 49 mA h g−1 at a current density of 5 mA g−1. Impedance studies for a symmetrical cell developed showed that the magnitude of the impedance is highest at 0% and 100 state of charge (SOC). [ABSTRACT FROM AUTHOR]

Summary: A series of anion exchange membranes (quaternized chitosan/cation metal‐organic framework [MIL‐X‐QCS]) were prepared via purposeful inserting the cationic metal‐organic framework as the multifunctional filler into quaternized chitosan (QCS). The successful preparation of the anion exchange membrane was confirmed by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), and Scanning electron microscope (SEM). In this research, we converted the charge‐balanced MOFs skeleton Cr‐MIL‐101 into the cationic metal skeleton (Cr‐MIL‐101)+Cl− by anion stripping, and cooperated with quaternary amine groups to construct a high‐speed OH− transmission channel. The introduction of a rigid MOF structure reduces the water uptake and swelling ratio of the composite membrane by 27% and 37%, respectively. At 80°C, the OH− conductivity of the MIL‐9‐QCS membrane (The composite membrane doped with 9 wt% Cr‐MIL‐101 crystals) reaches 2.30 × 10−2 S·cm−1 and the power density reached its maximum (90.2 mW·cm−2), and the tensile strength reaches 20.12 MPa, which was higher than 18.7 MPa of Nafion‐115 membrane. The spatial network structure of MOFs reduced the methanol permeability of MIL‐9‐QCS membrane by 24% compared with the original QCS membrane. Furthermore, the MIL‐9‐QCS composite membrane exhibited excellent alkali stability, where after being soaked in 2 mol L−1 NaOH solution at 60°C for 240 hours, its OH− conductivity still reached 77% of the initial value. [ABSTRACT FROM AUTHOR]

A series of qualitative descriptions and quantitative analyses was used to determine the lithofacies characteristics and recognize the favorable shale intervals of Dawuba Formation in the Ziyun area of South Qian Depression. The qualitative descriptions include core description and scanning electron microscope (SEM) observation. The quantitative analyses include X-ray diffraction, total organic content analysis, vitrinite reflectance, maceral composition, porosity, and permeability, as well as gas and element composition. The Dawuba Formation could be divided into four members. In general, the shale in the first and third members showed similarly high organic matter content with most samples in range of 2–2.5% and higher brittle mineral content with a content of quartz 40.53% and 33.21%, respectively, compared with the other two members, as well as high gas content. However, the first member shale samples exhibited much higher porosity and permeability than the third member shale samples. Furthermore, the shale gas in the first member was chiefly composed of methane (average: 83.63%), while that in the third member mainly consisted of nitrogen (average: 79.92%). Hence, the first member should be regarded as the most favorable target. [ABSTRACT FROM AUTHOR]

Objectives. Soft denture liners provide a favorable environment for adhesion and colonization of microorganisms. This in vitro study aimed to examine the efficacy of different concentrations of copper oxide nanoparticles (CuO NPs) incorporation into soft denture liner on the biofilm formation of the microbial species. Methods. Field Emission Scanning Electron Microscopy (FESEM) images from NPs were recorded. Antifungal susceptibility testing of CuO NPs against five standard strains of Candida albicans (CBS 10261, 1905, 1912, 1949, 2730), Streptococcus mutans (ATCC35668), Streptococcus sobrinus (ATCC27607), and Streptococcus salivarius (ATCC9222) was performed by the broth microdilution method with the Clinical and Laboratory Standards Institute reference method. The biofilm inhibition percentages of CuO NPs on the soft denture liners were determined by XTT assay. Results. The characterization of CuO NPs by scanning electron microscope (SEM) analyses confirmed the synthesis of NPs with appropriate structure and size with a mean diameter of 18.3 ± 9.1 nm. The CuO NPs successfully inhibited the growth of the tested standard strains of C. albicans and Streptococcus spp. at concentrations ranging from 64 to 128 µg mL−1. Indeed, incorporation of CuO NPs at a concentration of 500 µg mL−1 into the soft denture liners exhibited a significant activity (75%) in inhibition of C. albicans. biofilm formation in a dose-dependent manner. The biofilm formation of C. albicans in the presence of CuO NPs was lower than Streptococcus spp. in comparison with the control group (p < 0.05). Conclusion. Incorporation of CuO NPs significantly decreased the colonization and plaque formation of the oral pathogens, especially C. albicans accumulation. These NPs may be useful as a promising agent for the antimicrobial management of soft denture liner materials. [ABSTRACT FROM AUTHOR]

Organic pores play an important role in shale reservoirs. Organic pores occur where shale gas was produced and accumulated. However, there is little scientific understanding of the distribution and connectivity of organic pores. Organic pore types and their structural characteristics were studied using a total organic carbon (TOC), thin section, focused ion beam scanning electron microscope (FIB-SEM), and nano-CT. The samples were from the Wufeng Formation in the Upper Ordovician and Longmaxi Formations from the lower Silurian. The results show that organic matter is mainly concentrated in the Wufeng Formation and the bottom of the Longmaxi Formation and that the middle and upper parts of the Longmaxi Formation contain a low amount of organic matter. The shale of the Wufeng-Longmaxi Formation has high maturity, and its organic pores are well developed. There are three types of organic pores: algae, graptolite, and pyrobitumen pores. The pore connectivity of shale with a high organic content is better than that of shale with a low organic content. The volume of the organic pores accounts for more than 50% of the volume of the organic matter. Majority of the organic pores have an aperture smaller than 100 nm and are round, nearly circular, and elliptical in morphology. Most of the organic pores in a shale formation are developed in pyrobitumen, and most of the larger organic pores are concentrated at the center of solid pyrobitumen. The organic pores in pyrobitumen have the best connectivity and are the most favorable reservoir spaces and migration channels for shale gas, which is a crucial point of reference for future research of shale gas. [ABSTRACT FROM AUTHOR]

The occurrence of the postharvest physiological disorder of dark spots on the peel of the ripened "Khai" banana has led to a reduction in its commercial value. The objective of the present study was to investigate the development mechanisms of senescence dark spots of the "Khai" (Musa AA group) banana peel in relation to chlorophyll degradation and stomata cell death. Freshly harvested bananas (commercial mature green stage) were let to ripened at 25 ± 2°C (90%–95% RH). Peel color, senescent spots, DNA degradation, chlorophyll content, chlorophyll‐degrading enzyme activities were assessed. The senescent dark spots developed on the ripened bananas right after 6 days of storage, which coincided with remarkably increased DNA degradation, and a rapid decreased of hue angle value and total chlorophyll content which indicated the chlorophyll degradation. The activities of chlorophyllase, chlorophyll‐degrading peroxidase and pheophytinase increased gradually to the highest point where the chlorophyll content drastically reduced and the appearance of the dark spots was first recorded after 6 days of storage. These dark spots were observed to be surrounded with a bright luminescent ring of hypermodified fluorescent chlorophyll catabolites (FCCs), the product of chlorophyll breakdown. Additionally, the scanning electron microscope (SEM) revealed that the dark spots were found to have originated from the collapsed cells around the stomata of the ripened banana peel whereby the chlorophyll was entirely diminished. Practical applications: This research revealed the senescent dark spot development mechanisms of the "Khai" banana peel. The dark spot development symptom on the banana peel surface was caused by the senescence and cell death of the relevant stomata, further associated with chlorophyll degradation. Therefore, any further research into minimizing the dark spot symptom must focus on preventing or delaying stomata senescence and cell death. [ABSTRACT FROM AUTHOR]

A total of 270 lactic acid bacteria (LAB) was isolated and screened for their antifungal activity against Penicillium expansumMUCL2919240. Fourteen isolates showed wide antifungal spectrum against seven molds involved in food spoilage. Among these, three LAB strains named 4F, 4JC, and 3MI3 were selected for their high activity and broad antifungal spectrum. To identify these isolates, API CH50 and 16S rRNA gene sequencing were performed. Results showed that 4F and 4 JC were identified as lactobacillus plantarum and 3MI3 as lactobacillus paracasei. Various treatments of Cell‐free supernatant (CFS) from LAB showed that the inhibitory effect was due to proteinaceous substances, organic acids, and hydrogen peroxide. Scanning electron microscope (SEM) was carried out to assess the effects of CFS on the morphology of fungi. Efficacy of the CFS as biopresevative in tomato paste, bread, black olives, and grapes was tested and showed fungal inhibition suggesting its use in different food technologies. Practical applications: Food spoilage caused by molds and yeasts represents an important issue in industries. The preservation of these products is done through the use of chemicals that are harmful. And with the trend toward the consumption of natural products and the demand for clean labels it becomes essential to research natural preservative. In our study we report the improvement of quality and shelf life of tomato paste, bread, black olives, and grapes using antifungal lactobacillus plantarum 4F against Penicillium expansum and Aspergillus fumigatus, by producing antifungal substances that cause mycelial breakage of target mold. [ABSTRACT FROM AUTHOR]

Organic pores play an important role in shale reservoirs. Organic pores occur where shale gas was produced and accumulated. However, there is little scientific understanding of the distribution and connectivity of organic pores. Organic pore types and their structural characteristics were studied using a total organic carbon (TOC), thin section, focused ion beam scanning electron microscope (FIB-SEM), and nano-CT. The samples were from the Wufeng Formation in the Upper Ordovician and Longmaxi Formations from the lower Silurian. The results show that organic matter is mainly concentrated in the Wufeng Formation and the bottom of the Longmaxi Formation and that the middle and upper parts of the Longmaxi Formation contain a low amount of organic matter. The shale of the Wufeng-Longmaxi Formation has high maturity, and its organic pores are well developed. There are three types of organic pores: algae, graptolite, and pyrobitumen pores. The pore connectivity of shale with a high organic content is better than that of shale with a low organic content. The volume of the organic pores accounts for more than 50% of the volume of the organic matter. Majority of the organic pores have an aperture smaller than 100 nm and are round, nearly circular, and elliptical in morphology. Most of the organic pores in a shale formation are developed in pyrobitumen, and most of the larger organic pores are concentrated at the center of solid pyrobitumen. The organic pores in pyrobitumen have the best connectivity and are the most favorable reservoir spaces and migration channels for shale gas, which is a crucial point of reference for future research of shale gas. [ABSTRACT FROM AUTHOR]

In situ g-C3N4@ZnO nanocomposites (with 0, 1, 3, 5, and 7 wt.% of g-C3N4 in nanocomposite) were synthesized via a one-pot hydrothermal method using precursors of urea, zinc nitrate hexahydrate, and hexamethylenetetramine. The g-C3N4@ZnO nanocomposites were characterized by X-ray diffraction, scanning electron microscope, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The photocatalyst activity of g-C3N4@ZnO nanocomposites was evaluated via methylene blue degradation experiment under visible light irradiation. The g-C3N4@ZnO nanocomposites showed an enhancement in photocatalytic activity in comparison to pure ZnO which increased with the g-C3N4 content (1, 3, 5, and 7 wt.%) in nanocomposites. The photocatalytic activity reached the highest efficiency of 96.8% when the content of g-C3N4 was 7.0 wt.%. Nanocomposite having 7.0 wt.% of g-C3N4 also showed good recyclability with degradation efficiency higher than 90% even in the 4th use. The improvement of photocatalytic activity could be attributed to the adsorption ability and effective separation of electron-hole pairs between g-C3N4 and ZnO. This work implies a simple method to in situ prepare the nanocomposite material of g-C3N4 and semiconductors oxide for photocatalyst applications with high efficiency and good recyclability. [ABSTRACT FROM AUTHOR]

Background. Patients with tooth sensitivity are frequently exposed to desensitizing agents on a regular basis. These agents might have an impact on the surface properties and color of existing oral restorations. Accordingly, this study aimed to investigate the color stability, surface microhardness, and surface roughness of resin-modified glass ionomer (RMGIC), amalgomer CR, nanohybrid, and bulk-fill resin composites restorative materials after frequent exposure to a desensitizing agent. Materials and Methods. One hundred and twenty specimens were prepared; 10 specimens for each restorative material were equally subdivided into control and desensitizing-agent-exposed groups in each test. Surface microhardness and surface roughness were evaluated using the Vickers microhardness tester and surface profilometer, respectively. The color change was measured by using a spectrophotometer using the CIE L ∗ a ∗ b ∗ formula. Surface topography was analyzed using a scanning electron microscope (SEM). The collected data were analyzed with Student's t-test, one-way ANOVA, and Tukey post hoc tests for pairwise comparison at a level of significance of 0.05. Result. The frequent use of a desensitizing agent significantly decreased surface hardness of RMGIC, amalgomer, and bulk-fill composite materials. However, nanohybrid composite exhibited a significant surface hardness increase. The surface roughness of RMGIC, amalgomer, and nanohybrid composite increased significantly. Meanwhile, the bulk-fill resin composite showed a nonsignificant decrease. Both RMGIC and amalgomer exhibited significantly higher values of color change in comparison to those of nanohybrid and bulk-fill composites. Conclusion. The bulk-fill composite seems to be more resistant to discoloration and surface topographical changes than other tested materials on frequent exposure to the desensitizing agent. However, this exposure may pose a negative impact on its surface hardness. Bulk-fill resin composite may be the most suitable esthetic restorative in patients who frequently use desensitizing agents. [ABSTRACT FROM AUTHOR]

Summary: Here we present the study of supercapacitors based on molybdenum disulfide and poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (MoS2/PEDOT:PSS) composite electrodes deposited by spray‐coating. To produce the MoS2/PEDOT:PSS composite ink, dispersions of hydrothermally synthesized MoS2 and PEDOT:PSS were mixed in different weight proportions. Electrodes containing only PEDOT:PSS and MoS2 were also fabricated for comparison. The composite films were deposited by transferring the as‐prepared inks to an airbrush coupled to a modified 3D printer base with in‐line displacement. The films were characterized in terms of the scanning electron microscope (SEM), Raman spectroscopy, and sheet resistance. The electrochemical properties of supercapacitors were evaluated by cyclic voltammetry (CV), galvanostatic charge/discharges (GCD) techniques, impedance spectroscopy (IS), and their correlated parameters. The maximum specific capacitance of the MoS2‐based supercapacitor was estimated to be 145.9 F g−1 at 1 mV s−1, while the 3:1 MoS2/PEDOT:PSS weight ratio supercapacitor exhibited a specific capacitance of 131.1 F g−1. Despite the slightly lower CSP, the 3:1 device provided a better overall performance, with a remarkably higher energy density of 11.2 Wh kg−1 and a maximum power density of 1020 W kg−1. It also displayed better long‐term cycle stability, retaining 92% of its initial capacitance after 1000 CV cycles (against 54% of MoS2 devices). In summary, we demonstrated the study and production of a high‐performance supercapacitor with spray‐deposited MoS2/PEDOT:PSS composite electrodes, in which the production can be easily scalable for mass production and practical applications. [ABSTRACT FROM AUTHOR]

Summary: In this study, a simple and facile electrochemical deposition technique was employed to fabricate fluorine‐doped tin oxide‐based polydiphenylamine‐polyaniline/phosphotungstic acid copolymer nanocomposite modified electrode (FTO/PDPA‐PANI/PTA) for high‐performance supercapacitors application. Crystalline and morphological structure and coating thickness of PDPA‐PANI/PTA nanocomposite on FTO were characterized using X‐ray diffraction, scanning electron microscope, and atomic force microscope. The fabricated nanohybrid electrode exhibits superior specific capacitance of 360 Fg−1 at 1 mA current density. The higher capacitive behavior and cyclic steadiness of FTO/PDPA‐PANI/PTA modified electrode were achieved because of the presence of tungsten in the PDPA/PANI co‐polymer nanonetworks provide efficient interaction which enhances the fast electron transfer progressions. Electrochemical impedance spectroscopic (EIS) studies ensure the capacitive behavior of the electrodeposited nanohybrid modified electrode with a characteristic EIS semicircle in the lower frequency region. Further, a superior specific capacitance with 82% excellent capacitance retention after 1000 cycles, recommends a practical application in supercapacitor device electrodes. [ABSTRACT FROM AUTHOR]

This paper studies the tribological properties of the ZrO2-coated spherical joint pair of the axial piston pump in a high water-based emulsion medium. Firstly, atmospheric plasma spraying was used to prepare the ZrO2 coating on the surface of the spherical joint pair. Secondly, the tribological characteristics of the steel-steel pair and ceramic-ceramic pair were analyzed by the friction and wear testing machine under the conditions of a high water-based emulsion concentration, load size, and load frequency. White light interference three-dimensional surface profiler and scanning electron microscope were used to analyze the original and worn surfaces of the samples, and then the friction and wear of the different material pairs were discussed. The results show that the friction reduction and wear resistance of the ceramic ball joint are superior to those of the steel ball joint. When the load is 100 N, the frequency is 1 Hz, and the emulsion concentration is 5%, and the friction coefficient and wear loss of the ceramic-ceramic ball joint pair are the lowest. The emulsion concentration and load have great influence on the friction coefficient and wear amount, while the frequency has little influence on them. With increasing concentration of the emulsion, the friction coefficient decreases and tends to be stable, but with increasing of load, the friction coefficient and wear increase. The friction coefficient and wear loss of the ceramic-ceramic ball joint in pure water are 0.25 times higher than those of the steel ball joint under the same working conditions. Therefore, when the concentration of the high water-based emulsion is 5%, 100 N load, 1 Hz frequency, the ceramic-ceramic ball joints display the best friction and wear resistance of the two. The research results provide a theoretical basis for the design, manufacture, and application of the ceramic coating hydraulic components in a high water-based emulsion medium. [ABSTRACT FROM AUTHOR]

Due to their remarkable properties, cellulose nanomaterials are emerging materials for wastewater (WW) treatment. In this study, both pristine cellulose nanomaterial (CNM) and sodium periodate modified cellulose nanomaterial (NaIO4-CNM) were prepared from the stem of the Erythrina brucei plant for the removal of Pb(II) ions from WW. As-prepared CNMs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and thermogravimetric analysis with differential thermogravimetry (TGA-DTG) analysis. The as-prepared and characterized CNMs were tested for the removal of Pb(II) ions from secondary run-off wastewater (SERWW). Langmuir and Freundlich adsorption isotherms were certainly fixed to a maximum Pb(II) ions uptake capability (Qmax) of 91.74 and 384.62 mg g−1 by CNM and NaIO4-CNM adsorbents, respectively. The pseudo-second-order (PSO) kinetics model was well fitted to the uptake process. Results revealed that the percentage removal (%R) of Pb(II) ions was decreased by the presence of nitrogen and organic matter, but not affected by the presence of phosphorous in SERWW. Due to its high efficiency, NaIO4-CNM was selected for the regeneration study. The regeneration study was conducted after desorption of Pb(II) ions from the adsorbent by the addition of HCl, and the regenerated sorbent was reused as an adsorbent for at least 13 successive cycles. The results indicated excellent recycling capabilities, and the adsorbent was used as adsorbing material for the removal of Pb(II) ions from SERWW after 13 successive cycles without significant efficient loss. [ABSTRACT FROM AUTHOR]

Asphalt binder film thickness has relation to mixing temperature and binder content in hot mix asphalt, which influences mixture's performance. A significant variation in assessing the asphalt binder film thickness has been observed in the literature. Development of state of the art technology and Superpave specification requires the study of actual asphalt binder film thickness at micro-level. This study estimates asphalt binder film thickness at micro-level and compares results with those obtained through analytical models from the previous studies. The study utilizes different asphalt mixtures at various mixing temperatures and binder contents. The asphalt binder film thickness around the finest particles of 500 nm (0.5 micron) size in asphalt mastic was detected and measured by image analysis (using scanning electron microscope) and elemental analysis (using energy dispersive X-ray spectroscopy) at magnifying power of ×30,000. The analytical estimation revealed that the asphalt binder film thickness for the aforementioned conditions varies from 9 μm to 13 μm, with a fair relationship to binder content and mixing temperature. However, results obtained from image analysis revealed that the asphalt binder film thickness varies from 0.5 μm to 2.4 μm, with no relation to binder content and mixing temperature. The image analysis showed that the asphalt mixtures mostly contain asphalt mortar and asphalt mastic, occurring in irregular shape. It was also found that the asphalt binder film does exist as a separate entity inside the asphalt mastic in the form of a band around the filler particles as non-absorbed binder, which fills the approximate distance of 0.5 to 2.5 microns among filler particles. [ABSTRACT FROM AUTHOR]

As an essential component in shale, OM (organic matter) grains and their arrangements may play essential roles in affecting the anisotropy of the reservoir. However, OM grains are commonly treated as an evenly distributed isotropic medium in current studies, and few works have been done to investigate their detailed arrangement characteristics. In this study, terrestrial and marine shale samples were collected from three different shale plays in China, and the arrangement characteristics of OM grains in each sample were investigated by SEM (scanning electron microscope) image analysis. The results indicate that OM grains in shale are not evenly distributed in isotropic medium, and their directional alignment is pervasive in both marine and terrestrial shale. OM grains in shale tend to subparallel to the bedding section, and their orientation degree and controlling factors differ among different shales. OM grains in samples from terrestrial C-7(Chang-7 Formation) exhibit the strongest directionality in their arrangement, and OM grains in samples from marine LMX (Longmaxi Formation) shale in the Fuling area also exhibit strong directional alignment. While in samples from marine LMX shale in the Baojing area, their directional alignment is much weaker. Shales with high clay content, high TOC (total organic carbon), low thermal maturity, and flat reservoir structure get more OM grains parallel to the bedding section. The biogenetic texture of graptolite in marine LMX shale is the dominating factor leading to the strong directional alignment of the OM grains. However, syncline structure may disorganize the preformed directional alignment and weaken the directionality of the OM grains, which results in the OM arrangement difference between LMX samples from Fuling and Baojing. While the compaction of the layered clay particles is the dominating mechanism leading to the strong directional alignment of the OM grains in terrestrial shale samples from C-7. [ABSTRACT FROM AUTHOR]

By using proximate analysis, X-ray diffraction mineral analysis, scanning electron microscope, contact angle measurement, and settlement simulation experiment, the coal fines produced from the coalbed methane wells of Binchang area were used to study the characteristics including particle size distribution, composition, morphology, wettability, and settleability. The results show that the particle size of coal fines produced from coalbed methane wells are mainly >20 mesh, ranging of 1-400 μm, and the particle size distribution curve is mainly dominated by the main-secondary bimodal type, with the main peak of 30-300 μm. The particle size from large to small is drill cutting coal fines, flowback coal fines, bailing coal fines, and pipeline filter coal fines. In terms of ash content, coal fines are higher than coal seam, and drilling cuttings are higher than bailing coal fines, while the fixed carbon content of the former is lower than that of the latter. The minerals of coal fines are mainly kaolinite, illite, quartz, and other 6 minerals, and the mineral types of drilling coal fines are the most abundant, while the bailing coal fines only contain illite and quartz. The roundness of coal fine particles ranges from excellent to poor in the order of bailing coal fines, pipeline filter coal fines, flowback coal fines, and drilling cuttings. However, the sorting of drilling cuttings is excellent, and the particle edges are straight, neat, and smooth, while the sorting of bailing coal fines is poor, and the particle edges are curved, uneven, and rough. The contact angles of coal fines are 40.25°-69.5°, indicating hydrophilous. The wettability of bailing coal fines is better than that of drilling cuttings. The particle size has a negative correlation with the wettability effect. The more obvious the modification effect of positive wetting agent is, the worse the modification effect of negative wetting agent is. The modification of surfactant has nothing to do with the particle size of the coal fines, but is closely related to organic components and minerals. The larger the coal particle size, the higher the settling rate, and the higher the ash content and the lower the fixed carbon content, the faster the settling rate. With the dividing point 150 mesh, the settling rate of large particles is mainly affected by particle size, while that of small particles is affected by the composition. [ABSTRACT FROM AUTHOR]

Actinidia arguta pollen owns abundant nutrients, such as vitamins, polyphenols, etc., however, little research on its antioxidant ability and biological function was conducted. In this study, we observed A. arguta pollen spore structure by SEM (Scanning electron microscope), analyzed the phenolic composition of A. arguta pollen extract (AAPE) obtained by four extraction methods (A: ultrasound-assisted extraction with water, B: heat reflux extraction with water, C: ultrasound-assisted extraction with ethanol, and D: heat reflux extraction with ethanol). Total phenolic content, total flavonoid content, antioxidant activities (ferric reducing/antioxidant power [FRAP], chelating activity, and DPPH·scavenging activity) were also determined. Finally, we investigated its protective effect on DNA and lymphocytes damage response to oxidative stress. The results showed that the morphology of A. arguta pollen was similar to other pollen of the genus A. Lindl., but differs from them slightly in the specific morphology indicators. What is more, AAPE obtained by different extraction methods exhibited a protective effect against DNA oxidative damage, they also possessed a strong cytoprotection effect on mouse lymphocytes, especially the extraction obtained by method C, which had the highest total phenolic content (15.05 ± 0.34 mg GAE/g), strong ferrous ion-chelating ability (0.37 ± 0.023 mg Na2EDTA/g), DPPH· scavenging activity (IC50 = 0.14 ± 0.04 mg/ml), and FRAP (7.13 ± 0.33 mg Trolox/g). This paper provided a new edible natural antioxidant for human which will protect us from oxidative stress. Practical applications This study was the first to report the morphology of Actinidia arguta pollen by SEM analysis, and studied the effects of different extraction methods on antioxidant activities and cytoprotective effect of A. arguta pollen extract. We believed that our research makes a significant contribution to the literature, because the results of this research provide a reference for the development of a new edible natural antioxidant. [ABSTRACT FROM AUTHOR]

Summary: In the process of one‐step synthesis of methylal via methanol oxidation, the design and research of various dual‐function catalysts are important and studies on the influence of reaction conditions on this type of process are scarce. We explored the influence of reaction temperature, reaction space velocity, and the feed ratio of methanol to air on the catalytic effect of the process based on the Fe‐Mo‐based bifunction catalyst and discovered the most appropriate reaction conditions for the process. Results showed that excessively high reaction temperatures were not conducive to the formation of target product Dimethoxymethane (DMM) and this was verified from the perspective of thermodynamic analysis. At the same time, through Brunaure Emmett Teller (BET), X‐ray diffraction, scanning electron microscope, NH3‐temperature‐programmed chemisorption, and Pyridine Fourier Infrared (PY‐FTIR) characterization, analysis of the microstructure and surface characteristics of the catalyst showed that an excessively high reaction temperature caused accumulation of metal oxides on the catalyst surface to block pores and reduce the specific surface area. This also destroyed the active acidic sites on the catalyst surface and weakened the acidity of the catalyst, thereby reducing catalytic activity. Investigation showed that excessively high reaction space velocity caused most of the formaldehyde obtained by catalyzing the initial oxidative dehydrogenation to fail to undergo polycondensation with methanol after desorption in time to obtain DMM, leading to a significant decrease in DMM selectivity. Investigation of the methanol‐air feed ratio showed that when CH3OH:air = 1.5, the methylal selectivity was highest and catalytic activity had improved. Orthogonal experiments showed that optimal reaction conditions of the process were 663 K, 15 000 h−1 and CH3OH: air = 0.82. In addition, compared with other bifunctional catalysts of this process, the self‐made Mo:Fe(2)/HZSM‐5 bifunctional catalyst exhibited high stability and carbon deposition resistance under severe operating conditions. [ABSTRACT FROM AUTHOR]

Summary: This study investigated the structural, morphological, and optical absorption of three separate perovskites (NaPbI3, CsPbI3, and LiPbI3) developed by a low‐cost and massive hydrothermal production technique. For all samples, X‐ray diffraction (XRD) measurement demonstrated the growth of perovskites in the hexagonal phase along (002) orientation. From the scanning electron microscope (SEM) analyses, the perovskites have mixed morphologies between nano/micro rods and nano/microdiscs. In the visible field, NaPbI3 demonstrated stronger light absorption than CsPbI3 and LiPbI3. The prepared perovskites were tested under visible light as working electrodes for water splitting reactions using Na2S2O3 electrolyte. With 2.76% at 405 nm, the NaPbI3 perovskite photoelectrode in accordance with its optical properties showed the highest incident photon‐to‐current efficiency (IPCE) among the studied perovskites. Also, the NaPbI3 perovskite demonstrated higher PEC performance with an H2 production rate of 38 μmolh−1 cm−2 than many other reported perovskites. The studied perovskites have high stability and reproductivity for the photoelectrochemical H2 production. [ABSTRACT FROM AUTHOR]

A novel antimicrobial food package material was designed by immobilization of medicinal plant Acalypha indica leaf extract on the polycaprolactone (PCL) nanofibrous mats which prevent the food materials from microbial contamination. The morphology of prepared mats was characterized by scanning electron microscope (SEM) images. The loading of plant extract onto the PCL nanofibrous mats was confirmed by XRD spectrum. The porosity percentage of the prepared electrospun PCL nanofibrous mats has been found from SEM image using ImageJ software. The A. indica extract immobilized PCL nanofibrous mats were analyzed for its thermal stability and anti‐bacterial activity. The immobilized nanofibrous mats were tested with food samples (carrot pieces) inoculated in bacterial culture in order to check for their microbial inhibitory effect and monitored its shelf life period. The results of the work declare that the A. indica leaf extract immobilized electrospun PCL nanofibrous mat act as an effective antimicrobial food package material. Practical applications: Nowadays, the microbial attack on foods may lead to major health issues worldwide. Many efforts have been taken for preservation and inhibition of such microbial attack on foods. The results of the present work reveal that the package material prepared by immobilization of natural antimicrobial plant extract into polycaprolactone nanofibrous mats vanish the bad odor emerges from foods due to microbial attack and increase the food shelf life period as well as food quality. Therefore, the prepared immobilized nanofibrous mats will serve as a promising package material for foods. [ABSTRACT FROM AUTHOR]

Improvement of geotechnical properties of soil by cementitious additives and nanomaterials is commonly used method. However, few systematic research studies on the co-effects of them on the geotechnical properties of loess have been explored. In the present research, the enhancement technique of loess was proposed based on the co-effects of graphene oxide (GO) and cement. In addition, the compactability, mechanical properties, water resistance, and microstructure of the GO/cement/loess ternary system were studied. The results revealed that, with the increase of incorporation of GO (0.03, 0.06, 0.09, and 0.12 wt. %), the optimum moisture decreased, while the dry density, mechanical properties, and water resistance increased significantly. And an optimum GO content of 0.09 wt. % was determined according to mechanical properties and water resistance. Moreover, the scanning electron microscope (SEM) results revealed that the microstructure was densified and the characteristics of pores were refined. And the co-work mechanisms of GO/cement on loess were summarized. All the results indicated that the GO/cement mixture has remarkable co-effects on the geotechnical properties of loess. [ABSTRACT FROM AUTHOR]

Summary: In this study, a green and high‐efficiency adsorbent was synthesized. First, magnetic cellulose (Fe3O4/CMC) was prepared by coprecipitation method and then it was compounded with functional graphene oxide (GO) to prepare magnetic cellulose‐supported GO composite (Fe3O4/CMC/GO). As prepared composite was characterized by Fourier transform infrared spectroscopy, X‐ray diffractometer, thermogravimetric, scanning electron microscope, Brunner‐Emmett‐Teller, and vibrating sample magnetometer. The adsorption properties were studied, and the effects of time, temperature, pH, and initial concentration on the adsorption process were investigated. The adsorption mechanism was also discussed. The results showed that the pseudo‐second‐order kinetic model and the Langmuir model were more consistent with the adsorption process of Cu2+ by adsorbents. The whole adsorption process was a spontaneous endothermic process, and the adsorption capacity reached the maximum (199.98 mg·g−1) when the pH was 6 to 7, the initial concentration was 200 mg·L−1, and the temperature was 318 K. The high adsorption rate (86.68%) can still be achieved after 5 cycles of adsorption‐desorption with 1 mol·L−1 dilute hydrochloric acid as eluent. [ABSTRACT FROM AUTHOR]

A water-jet erosion test was carried out on grade-A ship steel to study the interaction and erosion mechanism of the water jet on the steel surface. When the water jet impacted, a STSS-1 stress-detection module was used to collect the dynamic strain signal on the rear of the ship's plate, and a scanning electron microscope, transmission electron microscope, X-ray diffractometer, and other equipment were used to analyze the microstructure and phase of the grade-A ship steel before impact. The surface morphology of the material after impact was studied and analyzed. The impact stress of the water jet on the grade-A steel was an alternating stress, and the jet pressure decayed in the radial direction. The material surface was fatigued under the action of the jet alternating stress. After the water-jet erosion, the central area of the grade-A steel was dominated by an elongated cementite hard phase, and the peripheral area had a pearlite structure. A model for the jet erosion and peeling of grade-A ship steel was established to clarify the mechanism of erosion by the water jet. [ABSTRACT FROM AUTHOR]

Background: Amphibians decline globally due to infection with virulent bacteria, despite their vital roles in the ecosystem. The current study aimed at addressing the pathological and bacterial findings of the infected Pelophylax ridibundus indigenous to the Al‐Ahsa region. Many clinical signs were observed in the eggs, including discoloration, disintegration of the outer jelly coat; defects in morphology, and mortality were reported. Furthermore, neuromasts lacking apical cilia and microvilli were observed in the cleavage stages of the infected developing egg. Additionally, cutaneous hyperaemia, lethargy, peripheral oedema, subcutaneous haemorrhage and cutaneous ulcerations were observed in the infected P. ridibundus adults. Methods: Ribbons of frog eggs were collected from Al‐Ahsa oasis, the Eastern region, Kingdom of Saudi Arabia (KSA), and examined under light and scanning electron microscope. The developed eggs and adults were further examined using a dissecting microscope to determine signs of infection. A bacterial strain designated as PRE‐1 was isolated from the infected eggs, identified genotypically and then characterized phenotypically. Strain PRE‐1 was identified as Aeromonas hydrophila based on the comparative gene sequences of the 16S rRNA gene at identity level of (99.92%). Furthermore, phylogenetic relationship based on the 16S rRNA gene sequences of our strain and other relevant strains Aeromonas spp. showed that PRE‐1 formed a cluster with A. hydrophila (99% bootstrap support), providing a robustness to the identification of PRE‐1 as A. hydrophila. This bacterium was found to be associated with disease outbursts in the marsh frogs from the Al‐Ahsa region. Conclusion: It is important to continue monitoring the emerging diseases so that their cause can be discerned, and appropriate protocols can be applied to limit the spread of the loss of amphibians, which are vital for our ecosystem. [ABSTRACT FROM AUTHOR]

In this paper, a magnetic graphene oxide (MGO) composite was prepared by the click reaction between the alkyne-modified Fe3O4 nanoparticles and the azide-modified graphene oxide for the purpose of removing the Congo red (CR) dye from water. The deposition of the Fe3O4 nanoparticles on the graphene oxide to successfully prepare the MGO composite was evidenced by the Fourier-transform infrared spectrometer, wide-angle X-ray diffraction equipment, scanning electron microscope, thermal gravimetric analyzer, and Raman spectrometer. The value of saturation magnetization for the MGO composite was 34.9 emu/g. The CR absorption capacities of the MGO composite increased first and then decreased as the pH value increased. It was found that the maximum adsorption capacity of the MGO composite for the CR was as high as 769.2 mg/g. In the absorption-desorption experiment, the CR absorption capacities of the MGO composite from the second cycle to the fifth cycle remained stable to be about 130 mg/g. Moreover, both the Langmuir model for the adsorption isotherm and the pseudo-second-order kinetic model could be used to describe the CR absorption behaviors of the MGO composite. [ABSTRACT FROM AUTHOR]

Sand-based cemented backfill (SBCB) mining technology is instrumental in utilizing coal resources buried under the water bodies. SBCB is exposed to the long-term action of mining-induced stresses in the goaf and groundwater permeating via microcracks along the rock strata. Studying the permeability evolution of SBCB under varying stress states is crucial for protecting coal and water resources below the aquifer. This study is focused on the influence law of different stress states on the SBCB permeability exposed to groundwater, which was tested under different axial and confining pressures using a laboratory seepage meter, particle size analyzer, scanning electron microscope (SEM), and X-ray diffractometer (XRD). Best-fitting quadratic polynomials linking the SBCB permeability with confining and axial pressures, respectively, were obtained via statistical processing of test results. The permeability gradually dropped within the elastic range as the confining and axial pressures increased. Moreover, an increase in the confining pressure caused a more dramatic reduction in the SBCB permeability than the axial pressure. Finally, the SBCB seepage mechanism under different stress states was revealed based on the particle size analysis, XRD patterns, and SEM microstructure. These findings are considered instrumental in substantiating safe mining of coal resources below the water bodies and above the confined groundwater. [ABSTRACT FROM AUTHOR]

Finding out the reasons for wellbore instability in the Longmaxi Formation and Wufeng Formation and putting forward drilling fluid technical countermeasures to strengthen and stabilize the wellbore are very crucial to horizontal drilling. Based on X-ray diffraction, electron microscope scanning, linear swelling experiment, and hot-rolling dispersion experiment, the physicochemical mechanism of wellbore instability in complex strata was revealed, and thus, the coordinated wellbore stability method can be put forward, which is "strengthening plugging of micropores, inhibiting filtrate invasion, and retarding pressure transmission." Using a sand bed filtration tester, high-temperature and high-pressure plugging simulation experimental device, and microporous membrane and other experimental devices, the oil-based drilling fluid treatment agent was researched and selected, and a set of an enhanced plugging drilling fluid system suitable for shale gas horizontal well was constructed. Its temperature resistance is 135°C and it has preferable contamination resistibility (10% NaCl, 1% CaCl2, and 8% poor clay). The bearing capacity of a 400 μm fracture is 5 MPa, and the filtration loss of 0.22 μm and 0.45 μm microporous membranes is zero. Compared with previous field drilling fluids, the constructed oil-based drilling fluid system has a greatly improved plugging ability and excellent performance in other aspects. [ABSTRACT FROM AUTHOR]

To ensure the sealing effect of gas extraction borehole in underground coal mine and improve the concentration of gas extraction, a kind of high-flow sealing material which can be injected into the microcracks around borehole was developed. The ultrafine cement as the base material, with water-reducing agent, expansion agent, retarder, the material, and water combined stir, will form a kind of colloid with high fluidity and slightly expansibility. This paper analyzes the differences between the new high-fluidity sealing material and ordinary cement materials in expansion performance, compressive strength, and sealing performance. Scanning electron microscope and mercury intrusion method were used to analyze the differences in microscopic morphology and pore structure of these two materials. The experimental results show that the new high-fluidity sealing material has an excellent fluidity of 295.5 mm with an expansion rate of 60 d being 1.562%. The new high-fluidity sealing material is convenient for grouting with strong material permeability and superior sealing performance. Field test results show that the effect of the new high-fluidity sealing material is better than the ordinary cement materials. The average drainage concentration and flux during the drainage period were 59.07% and 0.243 m3/min, respectively, which showed that the drainage efficiency was significantly improved. This novel sealing material is of great significance for improving the efficiency of drilling and drainage. [ABSTRACT FROM AUTHOR]

Reusable spacecraft is increasingly attracting researchers' attention. However, the experimental investigations on the turbine blade of the rocket engine are rarely published. Thus, the fatigue of a small impulse rocket turbine blade is explored in the current work. First, the specimen and the electrode of electrical discharge machining are carefully designed. Then, the electrical discharge machining is used to machine the specimen. To study the fatigue properties, the finite element analyses are separately performed on the blade model and the specimen. Based on the numerical results, a fatigue test is carried out to reproduce the most vulnerable position. Finally, the microstructural structures of the specimen are detected using the scanning electron microscope (SEM). Results show that (1) different from the aviation field, the specimen is unable to be machined with the welding method because it destroys the crucial details and the mechanical properties; (2) the maximum plastic strain is present at the leading edge close to the hub, at which a 760 μm corner crack appears at the 10113th fatigue cycle. This work provides a feasible method of using the EDM process to machine specimen for the small impulse turbine blade. [ABSTRACT FROM AUTHOR]

Gray cast iron HT200 material is a kind of pearlitic gray cast iron. Flake graphite in the gray cast iron greatly destroys the integrity of the matrix and affect the static strength. The influence of microscopic effects on the tensile static strength of gray cast iron HT200 specimens is investigated. The microstructures are observed by the scanning electron microscope. The failure tests are done under the static loads for the cylinder specimens of gray cast iron HT200. Then, an energy density zone (EDZ) model is applied to the simulation of the fracture process of the specimens. The energy density zone model is a macro/micro-trans-scale crack growth model that can depict a fracture process from an initial microdefect at the microscale to the final break at the macroscale. Three scale transitional functions as well as the size of the initial microdefect in the model represent the microscopic effects in a fracture process. Three scale transitional functions are speculated in view of the physical failure mechanisms. Two other material parameters in the model are determined from the test data. Thereby, the fracture process of gray cast iron specimens is numerically simulated, and the static strength values are calculated. The calculated values of static strength of gray cast iron specimens are identical to the test values. It is seen that the energy density zone model can accurately describe a fracture process of brittle materials like gray cast iron. In addition, the calculated results show that the microscopic effects did affect the static strength of gray cast material. [ABSTRACT FROM AUTHOR]

Summary: Supercapacitors are the electrochemical capacitors with high energy density. In this study, first, carbon aerogels (CAs) having different structural properties (surface areas and pore diameters) were synthesized. Their polypyrrole (PPy) composites on these CAs were synthesized via oxidative polymerization. The change in the capacitive properties depending on both different CA structural properties and PPy addition was determined. The materials were characterized by Fourier Transform Infrared Spectrocope (FTIR), X‐ray diffraction (XRD), nitrogen adsorption/desorption isotherms with Brunauer, Emmett and Teller (BET) method, scanning electron microscope (SEM), transmission Electron Microscope (TEM), elemental analysis and thermal gravimetric analysis (TGA) methods. Specific capacitances of the nanocomposites were determined by cyclic voltammetry (CV) method for fresh electrode and the aged electrode after 1000 cycles. It was observed that the specific capacitance of the composite obtained with the addition of PPy to the first type of carbon aerogel (CA1) material varies significantly and increased from 147 F g−1 (CA1) to 231 F g−1 (CA1/PPy). [ABSTRACT FROM AUTHOR]

During the long-term waterflooding (LTWF) in oil reservoirs, the formation is subject to permeability reduction as clay release and fine migration. At present, the mechanisms of permeability impairment in both macroscopic and microscopic pore structures in ultralow permeability reservoirs under LTWF are unclear. This statement epitomizes the main objective of this work: to understand how long-term waterflood changes porous structures and thus compromises permeability. The standard core flow experiments in conjunction with a couple of tests consisting of online nuclear magnetic resonance (NMR), high-pressure mercury intrusive penetration (HPMIP), X-ray diffraction (XRD), and scanning electron microscope (SEM) were performed to determine the mineral compositions, macrophysical properties, and micropore structures of two kinds of cores with different natures of pore distribution (i.e., unimodal and bimodal) before and after LTWF in Yan Chang field China. Results showed that the permeability decreased while the porosity increased after the LTWF. With respect to the pore size distribution, the small pores (SPs) decreased and the large pores (LPs) increased for both cores. For the unimodal core, the distribution curve shifted upwards with little change in the radius of the connected pores. For the bimodal core, the curve shifted to the right with an increasing radius of connected pores. With respect to the characteristic parameters, the average pore radius, median pore radius, structural coefficient, and tortuosity increased, while the relative sorting coefficient decreased. The relative changes of the parameters for the unimodal core were much smaller than those for the bimodal core. With respect to the clays, chlorite accounted for a majority proportion of the clays, and its content increased after LTWF. According to these changes, the mechanism of LTWF at different stages was interpreted. At the early stages, the blockage of the released clays occurred in SPs. Some of the middle pores (MPs) and LPs became larger due to the release and some of them became smaller due to the accumulation. At the middle stage, the blockage of SPs weakened. Some flow channels formed by MPs and LPs became dominant flow channels gradually. The effluxes of particles occurred, resulting in a significant increase in porosity. At the late stage, the stable flow channels have formed. The higher response of the bimodal core to LTWF could be attributed to its higher content of chlorite, which was more likely to accumulate. This study clarifies the mechanism of fine-migration-induced formation damage in microscopic pore structures and the migration pattern of clay minerals in ultralow permeability reservoirs. The work provides potential guidance for optimizing waterflood strategies in ultralow permeability reservoirs. [ABSTRACT FROM AUTHOR]

The effect of ultrasound treatment on water‐holding capacity (WHC) of beef during freezing‐thawing process was investigated. The results showed that the WHC of beef without ultrasound was 0.69 after one freezing–thawing process. In different stages of freezing and thawing (before freezing, during freezing, during thawing, and after thawing), the application of ultrasound (400 w, 45 kHz) could improve the WHC quality of beef: the WHC was improved most during thawing, which could reach 0.78. And then, ultrasound treatment could reduce hardness but improve springiness (p <.05) and pH value of beef in freezing–thawing process. Scanning electron microscope images showed that the lacuna of myofibrils increased, which indicated that the ultrasound could help to improve the WHC. Based on the results obtained, ultrasound treatment may be recommended as a useful means to improve the WHC of beef during freezing–thawing process. Practical applications: In the process of food production, raw meat may undergo repeated freezing–thawing, which would affect the quality of meat. Ultrasound, as a new technology, was used in this study. This study showed that ultrasound could help to improve the WHC of beef during freezing–thawing process. Therefore, it is reasonable to conclude that ultrasound can be used as an effective technology to improve the quality of beef during freezing–thawing process. [ABSTRACT FROM AUTHOR]

In this work, the polyamide (PA) membrane surface has been modified by coating of nanomaterials including graphene oxide (GO) and titanium dioxide (TiO2) to enhance membrane separation and antifouling properties. The influence of surface modification conditions on membrane characteristics has been investigated and compared with a base membrane. Membrane surface properties were determined through scanning electron microscope (SEM) images and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Membrane separation performance was determined through the possibility for the removal of methylene blue (MB) in water. Membrane antifouling property was evaluated by the maintained flux ratios (%) after 120 minutes of filtration. The experimental results showed that the appearance of hydrophilic groups after coating of GO and TiO2 nanocomposite materials with or without UV irradiation onto membrane surface made an improvement in the separation property of the coated membranes. The membrane flux increased from 28% to 61%; meanwhile, the antifouling property of the coated membranes was improved clearly, especially for UV-irradiated PA/GO-TiO2 membrane. [ABSTRACT FROM AUTHOR]

Goaf sealing wall is set in the roadway close to the stop line of working face in an underground coal mine. However, the sealing wall is prone to crack or fracture under serious mining stress, resulting in water and air leakage from goaf. In this study, the combination of polymethylene polyphenyl polyisocyanate (PAPI) and methylene diphenyl diisocyanate (MDI) as component A and polyether polyols, catalysts, surfactants, chain extenders, and plasticizers as component B were investigated to optimize the exothermic, foaming, and mechanical properties of modified polyurethane (PU) as the filling material for goaf sealing wall. Firstly, the reaction temperature of specimens with different contents of polyether polyols was monitored using a dynamic acquisition system; secondly, the effect of polyether polyols, catalysts, and surfactants on foaming property was studied; then, uniaxial compression tests were developed to obtain compressive behavior; finally, the microstructure after uniaxial compression was observed by using a scanning electron microscope (SEM). The results indicate that the pure chemical slurry is superior to the combination of chemical slurry and sand in compressive strength and deformation behavior. The optimal mass ratio of polyether triols, polyether tetraols, catalysts, surfactants, chain extenders, and plasticizers is 11 : 9 : 1.0 : 0.5 : 1.2: 6 in component B due to the maximum reaction temperature of 121.4°C, the expansion ratio of 2.6, and the compressive strength of 7.97 MPa at the strain of 10% in this study. The research provides a solution for the construction of the sealing wall, which is of great significance to safety production in an underground coal mine. [ABSTRACT FROM AUTHOR]

Magnesium hydride (MgH2) is one of the competitive hydrogen storage materials on account of abundant reserves and high hydrogen content. The hydrolysis of MgH2 is an ideal and controllable chemical hydrogen generation process. However, the hydrolyzed product of MgH2 is a passivation layer on the surface of the magnesium hydride, which will make the reaction continuity worse and reduce the rate of hydrogen release. In this work, hydrogen generation is controllably achieved by regulating the change of the surface tension value in the hydrolysis, a variety of surfactants were systematically investigated for the effect of the hydrolysis of MgH2 In the meantime, the passivation layer of MgH2 was observed by scanning electron microscope (SEM), and the surface tension value of the solution with different surfactants were monitored, investing the mechanism of hydrolysis adding different surfactants. Results show that different surfactants have different effects on hydrogen generation. The hydrogen generation capacity from high to low is as follows: tetrapropylammonium bromide (TPABr), sodium dodecyl benzene sulfonate (SDBS), Ecosol 507, octadecyl trimethyl ammonium chloride (OTAC), sodium alcohol ether sulfate (AES), and fatty methyl ester sulfonate (FMES-70). When the ratio of MgH2 to TPABr was 5 : 1, the hydrogen generation was increased by 52% and 28.3%, respectively, at the time of 100 s and 300 s. When hydrolysis time exceeds 80 s, the hydrogen generation with AES and FMES-70 began to decrease; it was reduced by more than 20% at the time of 300 s. SEM reveals that surfactants can affect the crystalline arrangement of Mg(OH)2 and make the passivation layer three-dimensionally layered providing channels for H2O molecules to react with MgH2. [ABSTRACT FROM AUTHOR]

Agrifood by-products are a key element within Europe's sustainable strategies. Valorization and reuse of zero-waste technologies are becoming more popular, and they are commonly named as "second-generation food waste management." The present study is directed to the valuable extracts of "green" organic compounds from the by-products of fruit and berry/vegetable crops, which can be revalorized in sustainable chemical technology and engineering, namely, in the production of "green" synthesis of nanoparticles and for the inhibition of corrosion and scaling of metals in corrosive media. Numerous types of agrifood by-products (rapeseed pomace, sugar beet pulp, fodder radish cake, grape pomace, and pomegranate peels) were investigated. The waste extracts for corrosion and scale inhibitors of mild steel in tap water were prepared by the conventional extraction method that uses 2-propanol and characterized by gas chromatography-mass spectroscopy (GC-MS). Inhibition of scaling and corrosion was investigated in thermal scaling conditions on the surface of the electrode manufactured from mild steel. The LPR technique was applied to measure the corrosion rate, and the scaling rate was determined gravimetrically. The extracts were found to inhibit the corrosion rate 2-3 times, while only radish cake extract inhibited both the corrosion and scaling rates. The waste extracts to produce nanoparticles were prepared by the ultrasound-assisted water extraction with subsequent oxidation by oxygen purge and characterized by liquid chromatography-mass spectroscopy (LC-MS). The aqueous grape pomace and pomegranate peel extracts were screened for total phenolic content (TPC) and total flavonoid content (TFC). The reduction capacity of the extracts was assessed using ferric reducing power (FRAP) and phosphomolybdenum (PM) assays. AgNPs were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis. The particle size of AgNPs ranged between 40 and 50 nm. The antimicrobial activity of AgNPs was tested against Escherichia coli using the agar diffusion method and optical density. [ABSTRACT FROM AUTHOR]

Plant extracts have been regarded as "green" alternatives as additives for metal electropolishing improvement. Therefore, understanding the electrochemical properties and the reaction mechanisms of the electroactive compounds from the plant extracts is necessary to further explore the mechanism and application of the plant extract-based additives for metal dissolution. The C-steel electropolishing behavior in orthophosphoric acid using the galvanostatic polarization and weight loss methods was ascertained. This was inspected via anode potential-limiting current relationship measurement and comparison in a solution of regularly mounting concentrations (from 50 to 1800 ppm of methanolic marjoram, coriander seeds, chamomile, and guava leaves extract), and the influence of temperature on the dissolution kinetics was investigated. Surface morphologies, roughness, and reflection of investigated specimens were inspected with a scanning electron microscope (SEM), profilometry, and Vis-IR spectroscopy. Addition of methanolic plant extract to the electropolishing solution results in a lower limiting current. Retardation percentage gained from mass loss measurement is comparable with those obtained from measurements of galvanostatic polarization. Addition of 500 ppm of marjoram, coriander, chamomile, and guava leaves increases the degree of surface brightness and reflectance to 64.9, 56.59, 27, and 24.5, respectively, relative to electropolishing electrolyte-free solution 16. The roughness (Ra) decreased from 2.7 μm to 0.52 μm without addition of any material. Ra values are 0.28, 0.23, 0.21, and 0.17 μm in the presence of guava leaves, chamomile, coriander seeds, and marjoram. [ABSTRACT FROM AUTHOR]

Summary: A novel electrochemical approach was introduced for crosslinking resorcinol‐formaldehyde (RF) gels at room temperature without utilizing a catalyst or a buffer. The electrochemically cross‐linked gels and their subsequent activated carbons exhibited enhanced physical properties. They were characterized via different methods such as scanning electron microscope (SEM), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), and surface area and porosity analyzer. The gels prepared with this novel approach range from dark red to deep yellow in color; and consist of different particle sizes depending on the used voltage. FTIR spectra showed that the gels prepared with the novel and conventional methods have identical chemical identities. However, the RF gels prepared with the novel approach of synthesis expose more controllable properties such as pore structure, surface area, particle size, etc, than those prepared with the conventional method, which makes them easier to design for different applications. The corresponding activated carbons showed higher surface areas and narrower micropore distributions that can be varied easily with voltage, which is a key factor in this work as a controlling parameter. Consequently, the approach of crosslinking gels with electric power is important for the controlled preparation of many new and nontraditional cross‐linked gels for various applications. [ABSTRACT FROM AUTHOR]

Green synthesis approach was successful used extract was successful in preparing bimetallic zero-valent Iron/Copper nanoparticles [FB-nZVFe/Cu]. Scanning Electron Microscope [SEM], Fourier Transform Infrared Spectroscopy [FTIR], and Dispersive X-ray Spectroscopy [EDX] showing the synthesizing of FB-nZVFe/Cu. The removal efficiency of Caffeine [5 mg L−1] reached 86% under the conditions [0.2 g L−1, 45 min, and pH 5]. The adsorption data are more appropriate by the Langmuir model [R2 = 0.9987] with qmax = 34.34 mg g −1. Kinetic results showed that Caffeine uptake is following pseudo-second-order. Langmuir and pseudo-second-order are more appropriate in linear and non-linear models. Overall, FB-Fe/Cu is a committed green substance for removal Caffeine from aqueous solutions. Functional parameters affect investigated using the Linear regression analysis, we found them to account for over 98% of the variables affecting the removal procedure. [ABSTRACT FROM AUTHOR]

ZnS/glass and CdS/glass single layers and ZnS/CdS and CdS/ZnS heterojunction thin films were deposited by the chemical bath deposition method using zinc acetate and cadmium acetate as the metal ion sources and thioacetamide as a nonmetallic ion source in acidic medium. Na2EDTA was used as a complexing agent to control the free cation concentration. The single layer and heterojunction thin films were characterized with X-ray diffraction (XRD), a scanning electron microscope (SEM), energy dispersive X-ray (EDX), and a UV-VIS spectrometer. The XRD patterns of the CdS/glass thin film deposited on the soda lime glass substrate crystalized in the cubic structure with a single peak along the (111) plane. The ZnS/CdS heterojunction and ZnS/glass single layer thin films were crystalized in the hexagonal ZnS structure. The CdS/ZnS heterojunction thin film is nearly amorphous. The optical analysis results confirmed single band gap values of 2.75 eV and 2.5 eV for ZnS/CdS and CdS/ZnS heterojunction thin films, respectively. The CdS/glass and CdS/ZnS thin films have more imaginary dielectric components than the real part. The optical conductivity of the single layer and heterojunction films is in the order of 10 15 1/s. The optical study also confirmed refractive index values between 2 and 2.7 for ZnS/glass, ZnS/CdS, and CdS/ZnS thin films for incident photon energies between 1.2 eV and 3.8 eV. The surface morphology studies revealed compacted spherical grains covering the substrate surfaces with few cracks on ZnS/glass, ZnS/CdS, and CdS/glass and voids on CdS/ZnS thin films. The EDX result confirmed nearly 1 : 1 metallic to nonmetallic ion ratio in the single-layered thin films and the dominance of Zn ion over Cd ion in both ZnS/CdS and CdS/ZnS heterojunction thin films. [ABSTRACT FROM AUTHOR]

Diagenesis is one of the most predominant factors controlling reservoir quality in the deeply buried siliciclastic sandstones of the third member in the Eocene Shahejie Formation (Es3), in the Raoyang Sag, the Bohai Bay Basin. In this study, thin section, cathodoluminescence (CL), scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectrum, carbon and oxygen isotopes, and fluid inclusion analyses are used to restructure paragenetic sequences and detect origins of carbonate cements recorded in this deeply buried member. Based on petrographic analyses, the Es3 sandstones are identified as lithic arkoses and feldspathic litharenites at present, but derived from original arkoses and lithic arkoses, respectively. Geohistorically, the Es3 sandstones have undergone two diagenetic episodes of eogenesis and mesogenesis. Events observed during eogenesis include chemical compaction, leaching of feldspar, development of chlorite coating and kaolinite, precipitation of the first generation of quartz overgrowth (QogI), dissolution of feldspar, and precipitation of calcite and nonferroan dolomite cement. Mesogenetic alterations include chemical compaction, precipitation of kaolinite aggregate and the second generation of quartz overgrowth (QogII), precipitation of ankerite, development of I/S and illite, and formation of pyrite. Carbon and oxygen isotopic data show that calcite cements are characterized by 13C ( δ 13 C PDB ranging from -0.7‰ to 1.0‰ with an average of 0.1‰) and 18O ( δ 18 O SMOW varying from 12.3‰ to 19.0‰ with an average of 16.2‰); these stable isotopic data combined with Z value (from 114.69 to 122.18) indicate skeletal debris ( δ 13 C PDB ranging from -1.2‰ to -1.1‰ with an average of -1.15‰; δ 18 O SMOW varying from 23.0‰ to 23.2‰ with an average of 23.1‰) and ooids in adjacent carbonate beds involved in meteoric water and seawater from outside jointly served as the carbon sources. For nonferroan dolomite, the δ 13 C PDB value of -4.1‰ is a little bit negative than the calcite, and the δ 18 O SMOW of 14.3‰ is coincident with the calcite, which suggest the nonferroan dolomites come from the diagenetic fluids with a similar oxygen isotopic composition to that of the calcite but modified by the external acidic δ 13C-depleted water. However, the ankerites are actually rich in 12C ( δ 13 C PDB ranging from -10.0‰ to -1.2‰, mean = − 4.3 ‰) and 16O ( δ 18 O SMOW varying from 10.1‰ to 19.4‰, mean = 14.9 ‰), when combined with the distribution of cutting down along the direction pointing to sand-body center from the margin and microthermometric temperature (Th's) data mainly varying between 115.2°C and 135.5°C with an average of 96.0°C, indicating the main origination from the Es3 source rocks with effective feldspar buffer action for the acidic fluids in the margins of the Es3 sandstones. In addition, the necessary elements for ankerite such as Fe2+, Ca2+, and Mg2+ ions also come from organic matter and clay minerals during thermal maturation of the Es3 source rocks. The study provides insights into diagenetic processes and origination of carbonate cements in the Es3 sandstones; it will facilitate the cognition of predictive models of deeply buried sandstone reservoirs to some extent, which can reduce the risks involved in oil and gas exploration and development. [ABSTRACT FROM AUTHOR]

Summary: Ti‐substituted Na0.67Mn0.5Fe0.5O2 powders were fabricated by quenching at high temperatures, and the structural properties were investigated by Fourier transform infrared (FTIR), Scanning Electron Microscope (SEM), X‐ray powder diffraction (XRD), and X‐ray absorption spectroscopy (XAS) measurements. According to XRD analysis, it was not observed any impurity phases and it was found that the lattice constants of the powders were slightly increased by Ti content. The change in the valence state of both Mn and Fe ions was investigated by X‐ray absorption near edge structure (XANES), and it was found that Ti‐substitution caused a decrease in the valance state of Fe in Na0.67Mn0.5Fe0.5O2. Fourier transform (FT) of XANES showed that the local structure around the metal ions changed with the addition of Ti ions. The cycling voltammetry (CV) graphs of Ti‐substituted cells were almost the same as the pure sample, which may not change the cycling mechanism in the cells. According to galvanostatic cycling measurements at room temperature, the best performance was obtained with Ti‐substitution of 0.06 to 0.09 in the structure. The effect of environmental temperature in the battery cells was investigated at 10°C to 50°C, and it was found that the battery performance depends on the environmental temperatures. [ABSTRACT FROM AUTHOR]

Filling mining method can dispose of the tailings into filling slurry, which can be transported to the stope through pipelines to manage the ground pressure and protect the environment. To improve the flowability of filling slurry, additives are used more and more widely. However, some additives can increase the air content in the slurry. The air in the slurry will become pores in the hardened cemented paste backfill (CPB). Therefore, it is necessary to explore the influence of initial air content in fresh slurry on the compressive strength of CPB. In this paper, sodium dodecyl sulfate (SDS) was used to regulate the air content in the fresh slurry. After measuring the initial air content, the slurry was made into test blocks. Then, the uniaxial compressive strength (UCS) of CPB at 28 d age was tested, and the distribution of CPB microscopic pores was observed by scanning electron microscope (SEM). The results show that as the initial air content in fresh slurry increases, the UCS of CPB first increases and then decreases. Before the initial air content in fresh slurry is 6.03%, the CPB pores distribution is relatively uniform. However, after exceeding this value, "discontinuous contact" structures, pore groups, and macropores occur in CPB. Through the CPB microscopic force analysis, the mathematical model describing the effect of initial air content on UCS of CPB should be a combination of logarithmic function and quadratic polynomial. This work can provide a supplement to the theory of CPB strength. [ABSTRACT FROM AUTHOR]

Herein, we report low-cost and rare-earth-free Cu-doped Mg-Al alloys for drill-free plugging applications and present the influence of Al content on degradation behavior. The phase composition and microstructure of fabricated alloys were characterized by using a scanning electron microscope (SEM) and X-ray diffractometer (XRD). Also, degradation properties were investigated using hydrogen evolution tests and the electrochemical measurements. The results reveal that the Al content is directly related to the proportion of secondary phases, such as Mg2Cu, Mg17Al12, and MgAlCu. Moreover, the Mg17Al12 and MgAlCu phases are distributed at α-Mg grain boundaries, whereas the MgAlCu phase is distributed within the Mg matrix. Acceleration of degradation rate is found due to microgalvanic corrosion in Mg-xAl-2Cu (in wt.%, named as ACx2, x = 0, 3, 5, and 9) alloys. In this regard, Mg2Cu, Mg17Al12, and MgAlCu phases act as a microgalvanic cathode against anodic magnesium matrixes. As such, the degradation rate of ACx2 alloys in 3.5% NaCl solution is ranked from AC02, AC32, AC52, to AC92. In this context, the AC02 alloy shows the fastest degradation rate, 46 times higher than the AC92 alloy. This may provide a practical solution to develop good alternatives for drill-free plugging materials. [ABSTRACT FROM AUTHOR]

When aluminum alloy is present in a Cl−-rich environment, the surface oxide film is easily damaged, resulting in faster dissolution of the substrate. The application of graphene-modified anticorrosion coating can effectively prevent the occurrence of corrosion. In this study, to explore the corrosion resistance of graphene-modified anticorrosion coating on the surface of aluminum alloy, we prepared graphene-modified anticorrosion coating on the surface of aluminum alloy and investigated the corrosion resistance mechanism. Epoxy resin primer and polyurethane top coat were modified by predispersed reduced graphene oxide (rGO). Scanning electron microscope (SEM) and Raman spectrum were used to investigate the microstructure of graphene-modified anticorrosion coating, and it was found that the addition of rGO could effectively improve the porosity defect of epoxy resin primer. Electrochemical workstation was used to quickly characterize the corrosion resistance of graphene-modified anticorrosion coating, and the change of the electrochemical curve during soaking in 3.5% NaCl was investigated every 5 hours. It was found that the application of rGO to modify the anticorrosion coating could improve the corrosion resistance of the anticorrosion coating, and as the soaking time increased, the corrosion resistance of graphene-modified anticorrosion coating changed regularly. The study results indicated that when the content of rGO was 0.4%, the porosity of epoxy coating decreased from 1.54% to 0.33%, the porosity dropped by an order of magnitude, and the self-corrosion voltage was relatively positive (-0.72434 V). The self-corrosion current density was the lowest (1.948 × 10 − 6 A / c m 2 ), and at the low frequency, the impedance modulus was the highest (103). After the equivalent circuit fitting, the dispersion index was relatively high, the dispersion effect was relatively weak, and the corrosion resistance of the coating was improved. For graphene-modified anticorrosion coating, in the early stage of corrosion protection, the existence of pores and other defects in the coating might increase the dispersion effect, resulting in greatly decreased corrosion resistance of the coating. In the middle stage of corrosion protection, the pores in the coating would be completely filled by corrosive ions, resulting in a weakened dispersion effect. Therefore, the decrease in the corrosion resistance of the coating was slowed down and became stable. [ABSTRACT FROM AUTHOR]

Summary: Ti‐substituted Na0.67Mn0.5Fe0.5O2 powders were fabricated by quenching at high temperatures, and the structural properties were investigated by Fourier transform infrared (FTIR), Scanning Electron Microscope (SEM), X‐ray powder diffraction (XRD), and X‐ray absorption spectroscopy (XAS) measurements. According to XRD analysis, it was not observed any impurity phases and it was found that the lattice constants of the powders were slightly increased by Ti content. The change in the valence state of both Mn and Fe ions was investigated by X‐ray absorption near edge structure (XANES), and it was found that Ti‐substitution caused a decrease in the valance state of Fe in Na0.67Mn0.5Fe0.5O2. Fourier transform (FT) of XANES showed that the local structure around the metal ions changed with the addition of Ti ions. The cycling voltammetry (CV) graphs of Ti‐substituted cells were almost the same as the pure sample, which may not change the cycling mechanism in the cells. According to galvanostatic cycling measurements at room temperature, the best performance was obtained with Ti‐substitution of 0.06 to 0.09 in the structure. The effect of environmental temperature in the battery cells was investigated at 10°C to 50°C, and it was found that the battery performance depends on the environmental temperatures. [ABSTRACT FROM AUTHOR]

Summary: In this work, the co‐pyrolysis of pine sawdust and low‐density polyethylene (LDPE) was performed in a two‐stage fixed‐bed reactor to achieve hydrogen‐rich syngas and to investigate the effect of the parameters on gas yield and composition. Gas chromatography was used to confirm the content of the gas products. The pyrolysis was supported with Ni (in 5‐25 wt%) loaded on activated carbon (AC). The maximum hydrogen concentration was 392.8 mmol g−1 sample, which was achieved by the use of the 10% Ni‐AC catalyst. The influence of Ni loading on supporter was investigated by scanning electron microscope and transmission electron microscope techniques besides the thermogravity analysis. The increasing size of the Ni particles can be observed as a function of the Ni concentration on the catalyst. Carbon deposition was detected and the amorphous carbon seems more dominant than filamentous form. In addition, the effect of fluid residence time (water inlet and purge gas) on syngas yield was studied. Three different fluid residence times were investigated, and among them, the highest hydrogen yield was 392.8 mmol g−1sample at 1.57 minutes residence time. Furthermore, the catalyst lifetime was studied using 10 wt% of Ni containing AC, and the average hydrogen concentration was 196.0 mmol g−1 sample over 15 cycles. [ABSTRACT FROM AUTHOR]