Numerical modeling of the dispersion of ceramic nanoparticles during ultrasonic processing of aluminum-based nanocomposites

AbstractThe metal–matrix-nano-composites (MMNCs) in this study consist of a 6061 alloy matrix reinforced with 1.0wt.% SiC nanoparticles that are dispersed within the matrix using an ultrasonic cavitation dispersion technique available in the Solidification Laboratory at the University of Alabama.The required ultrasonic parameters to achieve (i) the required stirring and cavitation for suitable degassing and refining of the aluminum alloy and (ii) the adequate fluid flow characteristics for uniform dispersion of the nanoparticles into the 6061 matrix are being investigated in this study by using an in-house developed CFD ultrasonic cavitation model. The multiphase CFD model accounts for turbulent fluid flow, heat transfer, and the complex interaction between the molten alloy and nanoparticles by using the ANSYS's Fluent DDPM.The modeling parametric study includes the effects of the fluid flow, the ultrasonic probe location, nanoparticle size distribution, and initial location where the nanoparticles are released into the molten alloy. It was determined that the nanoparticles can be distributed quickly and uniformly into the molten 6061 alloy

Estimation of mechanics parameters of rock in consideration of confining pressure using monitoring while drilling data

During the drilling process, high-strength rock can lead to various issues such as drilling suppression, bit wear, and increased operational costs. To ensure safe and efficient drilling operations, it is crucial to accurately predict the strength parameters of the rock and recommend modifications to operational procedures. This paper proposes a low-cost and fast measurement method for predicting the strength parameters of rock in the field. To evaluate the effectiveness of this method, a drilling process monitoring experiment was conducted on sandstone, limestone, and granite. The experiment studied the effect of confining pressure on the response of cutting with an impregnated diamond bit. By analyzing the relationship between the thrust force, torque force, and penetration depth under different confining pressures, the researchers developed an analytical model for drilling that considers confining pressure, compressed crushed zone, and bit geometry. The results show that the confining pressure has a significant effect on the cutting response. As the confining pressure increases, the thrust force, torque force, and penetration depth at the cutting point also increase. Furthermore, a new measurement method was proposed to determine the strength parameters, such as cohesion, internal friction angle, and unconfined compressive strength. The estimated strength parameters for the three rock types using the drilling method were in good agreement with those of the standard laboratory test, with an error range of 10%. This method of estimating rock strength parameters is a practical tool for engineers. It can continuously and quickly obtain the drilling parameters of in-situ rocks

A Deep Learning Approach for Wireless Network Performance Classification Based on UAV Mobility Features

The unmanned aerial vehicle (UAV) has drawn attention from the military and researchers worldwide, which has advantages such as robust survivability and execution ability. Mobility models are usually used to describe the movement of nodes in drone networks. Different mobility models have been proposed for different application scenarios; currently, there is no unified mobility model that can be adapted to all scenarios. The mobility of nodes is an essential characteristic of mobile ad hoc networks (MANETs), and the motion state of nodes significantly impacts the network’s performance. Currently, most related studies focus on the establishment of mathematical models that describe the motion and connectivity characteristics of the mobility models with limited universality. In this study, we use a backpropagation neural network (BPNN) to explore the relationship between the motion characteristics of mobile nodes and the performance of routing protocols. The neural network is trained by extracting five indicators that describe the relationship between nodes and the global features of nodes. Our model shows good performance and accuracy of classification on new datasets with different motion features, verifying the correctness of the proposed idea, which can help the selection of mobility models and routing protocols in different application scenarios having the ability to avoid repeated experiments to obtain relevant network performance. This will help in the selection of mobility models for drone networks and the setting and optimization of routing protocols in future practical application scenarios

The complete chloroplast genome of Viburnum dilatatum (Adoxaceae)

Viburnum dilatatum Thunb. is a large deciduous tree of Adoxaceae. In this study, the chloroplast genome sequence of V. dilatatum is 158,392 bp, consisting of a large single-copy (LSC) region with 87,070 bp, a small single-copy (SSC) region with 18,242 bp , and two inverted repeat (IR) regions with 26,540 bp. The GC content in the chloroplast genome of C. julianae is 38.1%. The chloroplast genome of V. dilatatum contains 126 genes, including 83 protein-coding genes, 39 tRNA genes, and 4 rRNA genes. Phylogenetic tree showed that V. dilatatum was clustered with V. utile

Research on the Shale Porosity–TOC Maturity Relationship Based on an Improved Pore Space Characterization Method

Shale pore structure characterization is key to shale reservoir evaluation, sweet spot selection, and economic exploitation. It remains a challenge to accurately characterize shale micro-nano pores. Common experimental characterization methods for shale pore systems are listed, and advantages and weaknesses of each method are analyzed. An improved pore structure characterization method for shale is proposed by combining Helium and NMR. The new method does not affect shale samples and has a higher accuracy. The affecting factors for shale pore evolution for shale are also discussed, showing that organic matter content and maturity are key factors in total porosity development. Furthermore, a shale porosity–TOC maturity relationship chart is developed based on the experimental data of shale samples selected from six shale reservoirs. The application of this chart in Well X in the Gulong field of Songliao Basin proves its utility in evaluating shale reservoirs

Candidate Genes for Yellow Leaf Color in Common Wheat (Triticum aestivum L.) and Major Related Metabolic Pathways according to Transcriptome Profiling

The photosynthetic capacity and efficiency of a crop depends on the biosynthesis of photosynthetic pigments and chloroplast development. However, little is known about the molecular mechanisms of chloroplast development and chlorophyll (Chl) biosynthesis in common wheat because of its huge and complex genome. Ygm, a spontaneous yellow-green leaf color mutant of winter wheat, exhibits reduced Chl contents and abnormal chloroplast development. Thus, we searched for candidate genes associated with this phenotype. Comparative transcriptome profiling was performed using leaves from the yellow leaf color type (Y) and normal green color type (G) of the Ygm mutant progeny. We identified 1227 differentially expressed genes (DEGs) in Y compared with G (i.e., 689 upregulated genes and 538 downregulated genes). Gene ontology and pathway enrichment analyses indicated that the DEGs were involved in Chl biosynthesis (i.e., magnesium chelatase subunit H (CHLH) and protochlorophyllide oxidoreductase (POR) genes), carotenoid biosynthesis (i.e., β-carotene hydroxylase (BCH) genes), photosynthesis, and carbon fixation in photosynthetic organisms. We also identified heat shock protein (HSP) genes (sHSP, HSP70, HSP90, and DnaJ) and heat shock transcription factor genes that might have vital roles in chloroplast development. Quantitative RT-PCR analysis of the relevant DEGs confirmed the RNA-Seq results. Moreover, measurements of seven intermediate products involved in Chl biosynthesis and five carotenoid compounds involved in carotenoid-xanthophyll biosynthesis confirmed that CHLH and BCH are vital enzymes for the unusual leaf color phenotype in Y type. These results provide insights into leaf color variation in wheat at the transcriptional level

A Set of Molecular Markers to Accelerate Breeding and Determine Seed Purity of CMS Three-Line Hybrids in <i>Brassica napus</i>

Cytoplasmic male sterility (CMS) is the main mechanism employed to utilize the heterosis of Brassica napus. CMS three-line rapeseed hybrids have dramatically enhanced yield and brought about the global revolution of hybrid varieties, replacing conventional crop varieties. Over the last half century, China has led the development of hybrid Brassica napus varieties. Two sterile lines, polima (pol) and shaan 2A, were of particular importance for the establishment of three-line hybrid systems in rapeseed, which has opened up a new era of heterosis utilization. However, in current breeding practices, it takes up to three years to identify the restorer or maintainer relationship and the cytoplasmic type of any inbred material. This greatly affects the breeding speed of new varieties and inhibits the rapid development of the rapeseed industry. To address this problem, we developed a set of molecular markers for the identification of fertile cytoplasmic gene N and sterile cytoplasmic gene S, as well as for the fertile nucleus gene R and sterile nucleus gene r, based on differences in the gene sequences between the CMS line, maintainer line and restorer line of Brassica napus. Combining these markers can accurately identify the CMS line, maintainer and restorer of both the pol and shaan systems, as well as their hybrids. These markers can not only be used to identify of the maintainer and restorer relationship of inbred materials; they can also be used as general molecular markers to identify the CMS-type hybrid purity of pol and shaan systems

Numerical modeling of fluid flow and solidification phenomena during ultrasonic processing of metal-matrix-nanocomposites

In present study, 6061 and A356 based nano-composites are fabricated by using the ultrasonic stirring technology (UST) in a coreless induction furnace. SiC nanoparticles are used as the reinforcement. Nanoparticles are added into the molten metal and then dispersed by ultrasonic cavitation and acoustic streaming assisted by electromagnetic stirring. The applied UST parameters in the current experiments are used to validate a recently developed magneto-hydro-dynamics (MHD) model, which is capable to model the cavitation and nanoparticle dispersion during UST processing. The MHD model accounts for turbulent fluid flow, heat transfer and solidification, and electromagnetic field, as well as the complex interaction between the nanoparticles and both the molten and solidified alloys by using ANSYS Maxwell and ANSYS Fluent. Molecular dynamics (MD) simulations are conducted to analyze the complex interactions between the nanoparticle and the liquid/solid interface. The current modeling results demonstrate that a strong flow can disperse the nanoparticles relatively well during molten metal and solidification processes. Molecular dynamics simulation results prove that ultrafine particles (<< 1 µm) will be engulfed by the solidification front instead of being pushed, which is beneficial for nano-dispersion. Experimental results confirm that the nanoparticles are dispersed reasonably well in the metal matrix, but some insignificant agglomeration still occurs. Besides, SEM/EDS results show that C element tends to gather around the grain boundary area where the Si eutectic phase is located. (Published By University of Alabama Libraries

mtDNA D-loop mutations and mtDNA depletion among control and NRTI-treated children with AIDS.

<p>A: The ratio of mtDNA D-loop mutations in the control children (Group A, n = 50), children with AIDS treated for less than 36 months (Group B, n = 68) and children with AIDS treated for 36 to 72 months (Group C, n = 84). B: mtDNA depletion in control children (Group A, n = 50), children with AIDS treated for less than 36 months (Group B, n = 68) and children with AIDS treated for 36 to 72 months (Group C, n = 84); *P<0.01. C: mtDNA depletion in non-infected children (Group A) and 20 cases of age-matched, untreated, HIV-infected children (HIV-infection, n = 20), who came from our HIV blood samples bank and the total DNA in these samples were isolated for mtDNA loss specific assay.</p