A preliminary study of improving the MICP effects via the extractions from seashell nacre

In microbially induced calcium carbonate precipitation (MICP) process, it is the precipitated CaCO3 that cements loose sand particles together to improve their mechanical properties. Seashell nacre composed of CaCO3 is a natural product, which is worth researching for its great hardness, strength, and toughness. However, there is no study connecting this natural nacre mineralization with MICP. Therefore, a precedent herein is established to modify the MICP process via the water-soluble matrix (WSM) extracted from nacre, where WSM contributes to the great mechanical properties of nacre. Correspondingly, this study examines the effects of WSM with different concentrations on urease activity and strength as well as microstructure of bio-cemented sand samples. The experimental results show that a small number of WSM (50mg/L) can improve the average strength of bio-cemented sand samples 1.5 times. This is because 50mg/L WSM can significantly improve the urease activity of bacteria meanwhile increasing the Ca2+ utilization rate. Thus, more CaCO3 crystals are precipitated, and the higher UCS of bio-cemented sand samples is achieved. Moreover, the XRD results indicate that the precipitated CaCO3 is almost calcite, and only a little aragonite is detected when the concentration of WSM increases to 100mg/L. Additionally, the SEM images demonstrate that WSM involvement can affect the shapes and sizes of CaCO3 crystals. Overall, this work is an unprecedented exploration imitating nacre that hopefully paves way for future studies.

Green synthesis and characterization of zinc oxide nanoparticles using bush tea (Athrixia phylicoides DC) natural extract: assessment of the synthesis process.

Background: Nanoparticles are globally synthesized for their antimicrobial, anti-inflammatory, wound healing, catalytic, magnetic, optical, and electronic properties that have put them at the forefront of a wide variety of studies. Among them, zinc oxide (ZnO) has received much consideration due to its technological and medicinal applications. In this study, we report on the synthesis process of ZnO nanoparticles using Athrixia phylicoides DC natural extract as a reducing agent. Methods: Liquid chromatography–mass spectrometry (LC-MS) was used to identify the compounds responsible for the synthesis of ZnO nanoparticles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized through X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results: LC-MS results showed that different flavonoids and polyphenols, as well as Coumarin, an aromatic compound, reacted with the precursor to form ZnO nanoparticles. XRD and UV-Vis analysis confirmed the synthesis of ZnO nanoparticles, with a spherical shape showed in SEM images. The quasi-spherical ZnO crystals had an average crystallite size of 24 nm. EDS and FTIR analysis confirmed that the powders were pure with no other phase or impurity. Conclusions: This study successfully demonstrated that the natural plant extract of A. phylicoides DC. can be used in the bio-reduction of zinc nitrate hexahydrate to prepare pure ZnO nanoparticles, thus, extending the use of this plant to an industrial level.

Characteristics of ZnO and Al Doped ZnO Thin Films Prepared by Sol Gel Method for Solar Cell Applications

Pure and Al-doped ZnO (AZO) thin films with different aluminium (Al) concentrations (Al: 0.5, 1, 2, and 3 wt.%) were prepared on p-type Si(100) substrate by a dip-coating technique using different zinc and aluminum precursors. The structural, morphological, optical and electrical properties of these films were investigated using a number of techniques, including the X-Ray Diffraction (XRD), scanning electron microscopy (SEM), Atomic force electron microscopy (AFM), ultraviolet–visible spectrophotometry, photoluminescence(PL) spectroscopy and four-point probe technique. The X-ray diffraction (XRD) results shown that the obtained (AZO) films were polycrystalline with a highly c-axis preferred (002) orientation, and the average crystallites size decrease from 28.32 to 24.61 nm with the increase in Al dopant concentration. The studies demonstrated that the ZnO film had a good transparency in the visible range with the maximum transmittance of 95% and the band gaps (Eg) varied from 3.16 to 3.26 eV by alumium doping. Scanning electron microscopy (SEM) images showed that the surface morphology of the films changed with increase of Al-doping. The photoluminescence spectra also showed changed with Al-doping.

Distribution characteristics of microplastics in the soil of mangrove restoration wetland and the effects of microplastics on soil characteristics

Microplastics that enter the soil environment are transformed by migration and can affect soil properties, which in turn have an impact on soil function and biodiversity. In this study, we investigated the distribution of soil microplastics at different planting densities and their effects on soil properties in a mangrove restoration wetland. The results showed that the average abundance of soil microplastics in the study area was 2177.5 n/500g, with the largest proportion of 0.038-0.05 mm diameter microplastics accounting for 70.9% and the rest of the diameter microplastics accounting for less than 20%, indicating that the smaller the diameter microplastics are easy to accumulate in the wetland soil. The abundance of microplastics in the restored area by planting density was ranked as 0.5×0.5m > 1.0×0.5m > 1.0×1.0m > control area. Three microplastics, polyethylene terephthalate (PET, accounted for 52%), polyethylene (PE, accounted for 24%), and polypropylene (PP, accounted for 15%), were the most prevalent and dominant microplastics in the soils of the area. SEM images showed that fractures, tears, EDS spectroscopy showed that a large number of metals were detected on the surface of microplastics. PET can influence the distribution of soil particle size due to its adsorptive viscosity, which may affect soil structure. Apart from soil pH, all other physicochemical factors changed significantly in response to PET. Besides, the results of the CV analysis reflect that soils in vegetated areas are more susceptible to the effects of PET than bare ground soils resulting in greater variability in the properties.

Supplemental Material: Initial uplift of the Qilian Shan, northern Tibet since ca. 25 Ma: Implications for regional tectonics and origin of eolian deposition in Asia

Supplemental dataset: Detrital zircon U-Pb ages of the sandstone samples from the Lulehe and Hongshangou sections; Figure S1: SEM images of 129 grains from sandstone sample LLH-1 showing grain roundness characteristics; Figure S2: SEM images of 140 grains from sandstone sample LLH-2 showing grain roundness characteristics; Figure S3: SEM images of 123 grains from sandstone sample LLH-3 showing grain roundness characteristics; Figure S4: SEM images of 122 grains from sandstone sample HSG-7 showing grain roundness characteristics; Figure S5: SEM images of 123 grains from sandstone sample HSG-8 showing grain roundness characteristics; Figure S6: SEM images of 123 grains from sandstone sample HSG-9 showing grain roundness characteristics; Figure S7: SEM images of representative grains from the Lulehe and Hongshangou sections showing surface microtextures.

Supplemental Material: Initial uplift of the Qilian Shan, northern Tibet since ca. 25 Ma: Implications for regional tectonics and origin of eolian deposition in Asia

Supplemental dataset: Detrital zircon U-Pb ages of the sandstone samples from the Lulehe and Hongshangou sections; Figure S1: SEM images of 129 grains from sandstone sample LLH-1 showing grain roundness characteristics; Figure S2: SEM images of 140 grains from sandstone sample LLH-2 showing grain roundness characteristics; Figure S3: SEM images of 123 grains from sandstone sample LLH-3 showing grain roundness characteristics; Figure S4: SEM images of 122 grains from sandstone sample HSG-7 showing grain roundness characteristics; Figure S5: SEM images of 123 grains from sandstone sample HSG-8 showing grain roundness characteristics; Figure S6: SEM images of 123 grains from sandstone sample HSG-9 showing grain roundness characteristics; Figure S7: SEM images of representative grains from the Lulehe and Hongshangou sections showing surface microtextures.

Degradation mechanism of the superconducting performance of a Bi2212 cable under magnetic fields

In magnetic confinement fusion reactors, superconducting magnet systems are essential for generating and controlling high magnetic fields. To increase the magnetic field, new superconducting materials such as Bi2212 (Bi2Sr2CaCu2O8+x) have been selected in the design of magnet systems. However, the stability of the Bi2212 superconductor under magnetic fields must be studied for the routine and safe operation of magnet systems. In this work, the stability and degradation mechanism of a Bi2212 cable under magnetic fields were investigated. With a magnetic field of 5.8 T, the cable carrying 29 kA was exerted with a force of ~168.2 kN per meter. In the core area of the cable, moved wires were detected by computed tomography (CT). The macroscopic movement of the wires would vary with the axial position, which could be related to the twist structure. Then, the cable was decomposed, and the acquired wires were tested under 12 T at 4.2 K by four-probe method. The results indicated that the inner wires had relatively lower critical currents, which should be the reason for the degradation of cable performance. Scanning electron microscope (SEM) images of the superconducting phase within the wires confirmed that cracks existed in the superconducting phase of the inner wires, while intact crystals were found in that of the outer wires. The variation in microstructures gave rise to changes in the wire performance.

Synthesis and Characterization of Carboxymethyl Chitosan Nanosponges with Cyclodextrin Blends for Drug Solubility Improvement

This study aimed to enhance the solubility and release characteristics of docetaxel by synthesizing highly porous and stimuli responsive nanosponges, a nano-version of hydrogels with the additional qualities of both hydrogels and nano-systems. Nanosponges were prepared by the free radical polymerization technique and characterized by their solubilization efficiency, swelling studies, sol-gel studies, percentage entrapment efficiency, drug loading, FTIR, PXRD, TGA, DSC, SEM, zeta sizer and in vitro dissolution studies. In vivo toxicity study was conducted to assess the safety of the oral administration of prepared nanosponges. FTIR, TGA and DSC studies confirmed the successful grafting of components into the stable nano-polymeric network. A porous and sponge-like structure was visualized through SEM images. The particle size of the optimized formulation was observed in the range of 195 ± 3 nm. The fabricated nanosponges noticeably enhanced the drug loading and solubilization efficiency of docetaxel in aqueous media. The drug release of fabricated nanosponges was significantly higher at pH 6.8 as compared to pH 1.2 and 4.5. An acute oral toxicity study endorsed the safety of the system. Due to an efficient preparation technique, as well as its enhanced solubility, excellent physicochemical properties, improved dissolution and non-toxic nature, nanosponges could be an efficient and a promising approach for the oral delivery of poorly soluble drugs.

Performance enhancement of Scanning Electron Microscope using a Deep Convolutional Neural Network

We report noise reduction and image enhancement in Scanning Electron Microscope (SEM) imaging while maintaining a Fast-Scan rate during imaging, using a Deep Convolutional Neural Network (D-CNN). SEM images of non-conducting samples without conducting coating always suffer from charging phenomenon, giving rise to SEM images with low contrast or anomalous contrast and permanent damage to the sample. One of the ways to avoid this effect is to use Fast-Scan mode, which suppresses the charging effect fairly well. Unfortunately, this also introduces noise and gives blurred images. The D-CNN has been used to predict relatively noise-free images as obtained from a Slow-Scan from a noisy, Fast-Scan image. The predicted images from D-CNN have the sharpness of images obtained from a Slow-Scan rate while reducing the charging effect due to images obtained from Fast-Scan rates. We show that using the present method, and it is possible to increase the scanning rate by a factor of about seven with an output of image quality comparable to that of the Slow-Scan mode. We present experimental results in support of the proposed method.

Development of Al-SiC composite material from rice husk and its parametric assessment

In this research work, the development of Al-SiC composite material from rice husk and its parametric assessment is done using a CNC milling machine. They are further surface characterized, and mechanical properties such as BET surface area, SEM-EDX, and XRD, fracture toughness, tensile, and bending strength are studied. The machinability of the components is investigated for selected values of input-output parameters. Three castings, each with different particulate reinforcement combinations, are made with aluminum alloy (6061) using the stir casting method. BET surface area of extracted silica and Al-SiC composite material was found 374 m2/g and 150 m2/g, respectively. From results of BET surface area revealed that silica obtained from rice husk is more heterogeneous with a large surface area. A heterogeneous surface with larger pores was found through SEM images. XRD diffraction peaks show changes of amorphous silica into crystallinity in the composite material. The results also indicate that fracture toughness is very good at low temperatures and good machinability on CNC milling machines makes it suitable for aerospace applications.