Preparation and Mechanical Properties of Core-Shell PS&CeO2 Composite Abrasive Particles.

Core-shell composite abrasive particles are a topic of great interest in surface finishing. It is important to explore the preparation technology and performance parameters associated with them. In this paper, a core-shell composite abrasive particle made of polystyrene and cerium oxide (PS&CeO2, CSPC), which is rigid on the outside and flexible on the inside, is proposed. The microstructure, physical phase characteristics, and mechanical properties of the inner core and composite abrasive particles are investigated. PS microspheres and CSPC composite abrasive particles with different structural features were prepared through a series of experiments, morphological observations, and physical and chemical characterization experiments. Their microstructures and physical phase properties were investigated. The indentation load curves of the PS microspheres and CSPC composite abrasive samples were measured by using an atomic force microscope. The analysis focused on the effects of various dimensional and structural parameters on the modulus of elasticity of both PS microspheres and CSPC composite abrasive particles. The analysis shows that the experimentally prepared PS microspheres have good dispersion, a smooth surface, and a uniform particle size distribution. The prepared CSPC composite abrasive particles are regular spheres with rough, rice-like surfaces, low modulus of elasticity, and overall nonrigid and soft elastic properties. The results of this paper can provide a guide for the preparation technology, performance regulation, and application of polymer microspheres and core-shell composite abrasive particles in CMP.

Transcriptome-wide 5-methylcytosine modification profiling of long non-coding RNAs in A549 cells infected with H1N1 influenza A virus.

BACKGROUND: In recent years, accumulating evidences have revealed that influenza A virus (IAV) infections induce significant differential expression of host long noncoding RNAs (lncRNAs), some of which play important roles in the regulation of virus-host interactions and determining the virus pathogenesis. However, whether these lncRNAs bear post-translational modifications and how their differential expression is regulated remain largely unknown. In this study, the transcriptome-wide 5-methylcytosine (m5C) modification of lncRNAs in A549 cells infected with an H1N1 influenza A virus was analyzed and compared with uninfected cells by Methylated RNA immunoprecipitation sequencing (MeRIP-Seq). RESULTS: Our data identified 1317 upregulated m5C peaks and 1667 downregulated peaks in the H1N1 infected group. Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the differentially modified lncRNAs were associated with protein modification, organelle localization, nuclear export and other biological processes. Furthermore, conjoint analysis of the differentially modified (DM) and differentially expressed (DE) lncRNAs identified 143 'hyper-up', 81 'hypo-up', 6 'hypo-down' and 4 'hyper-down' lncRNAs. GO and KEGG analyses revealed that these DM and DE lncRNAs were predominantly associated with pathogen recognition and disease pathogenesis pathways, indicating that m5C modifications could play an important role in the regulation of host response to IAV replication by modulating the expression and/or stability of lncRNAs. CONCLUSION: This study presented the first m5C modification profile of lncRNAs in A549 cells infected with IAV and demonstrated a significant alteration of m5C modifications on host lncRNAs upon IAV infection. These data could give a reference to future researches on the roles of m5C methylation in virus infection.

Numerical Study on Effect of Aggregate Moisture on Mixing Process.

During the concrete mixing process, the transition of aggregates from a dry to a moist state introduces a crucial dynamic that significantly influences particle interaction, consequently impacting mixing homogeneity. In this paper, based on the discrete element method, the effect of aggregate moisture on the mixing process of sand and stone was investigated. The interaction between dry particles was described by the Hertz-Mindlin model, while the interaction between wet particles was calculated by the linear cohesion model considering the liquid bridge force. Additionally, a functional relationship between the moisture content and the parameters of the linear cohesive contact model was established. The results show that the numerical method can be employed to simulate the mixing process. Notably, when the moisture content of pebbles ranges from 0% to 0.75% and that of sand ranges from 0% to 10.9%, the linear cohesion model is deemed suitable. The standard deviation of the mixing homogeneity of wet particles is lower than that of dry particles for short mixing time, indicating that a small amount of liquid enhances mixing homogeneity. However, moisture has no obvious effect on mixing homogeneity for a long mixing time. This nuanced understanding of the interplay between moisture, particle interactions, and mixing duration contributes valuable insights to optimize concrete mixing processes.

Discrete element simulation of compression failure mechanism of SiC ceramic considering collinear flaws.

A particle-based numerical simulation model was established for SiC ceramics, and a method of deleting the particles along the specified direction was chosen to produce a pair of pre-existing collinear flaws. A serial of simulations were carried out to investigate the effects of inclination angle and ligament length on the failure mechanism under uniaxial compression. The laws of crack initiation and propagation as well as the distribution laws of the stress field and displacement field around the pre-existing flaws were analyzed. The results showed that the influence of inclination angle θ on micro-crack initiation, propagation and coalescence was more significant than that of ligament length L for pre-existing collinear flaws. Meanwhile, three coalescence models can be found with the increase of the inclination angle. By analyzing the evolution process of the displacement and stress fields during the loading process, it was clearly that the first crack was induced by the tensile stress concentration, and the secondary crack was initiated and propagated with tensile and shear stress. Moreover, the propagation mechanism of the micro-crack was closely related to the evolution behaviours of the stress and displacement fields.

Experimental Study on Chemical-Mechanical Synergistic Preparation for Cemented Carbide Insert Cutting Edge.

Typical edge defects in the edge region of a new cemented carbide insert without edge preparation include burrs, poor surface quality, micro-breakages, and irregularities along the edge. To address the problems in new cemented carbide inserts without edge preparations, a chemical-mechanical synergistic preparation (CMSP) method for the cemented carbide insert cutting edge was proposed. Firstly, the CMSP device for the insert cutting edge was constructed. Then, the polishing slurry of the CMSP for the insert cutting edge was optimized using the Taguchi method combined with a grey relation analysis and fuzzy inference. Finally, orthogonal experiments, the Taguchi method, and analysis of variance (ANOVA) were used to investigate the effect of the polishing plate's rotational speed, swing angle, and input frequency of the controller on the edge preparation process, and the parameters were optimized. The results showed that the best parameter combination for the polishing slurry for the cemented carbide inserts was the mass concentration of the abrasive particle of 10 wt%, the mass concentration of the oxidant of 10 wt%, the mass concentration of the dispersant of 2 wt%, and the pH of 8. The CMSP process parameter combination for the linear edge had the polishing plate's rotational speed of 90 rpm, the swing angle of 6°, and the input frequency of the controller of 5000 Hz. The optimum CMSP process parameter combination for the circular edge had the polishing plate's rotational speed of 90 rpm, the swing angle of 6°, and the input frequency of the controller of 7000 Hz. The polishing plate's rotational speed had the most significant impact on the edge preparation process, followed by the swing angle, and the effect of the input frequency of the controller was the smallest. This study demonstrated that CMSP is a potential way to treat the cemented carbide insert cutting edge in a tool enterprise.

Investigation of the Effects of Roller Spreading Parameters on Powder Bed Quality in Selective Laser Sintering.

Powder spreading is one of crucial steps in selective laser sintering (SLS), which controls the quality of the powder bed and affects the quality of the printed parts. It is not advisable to use empirical methods or trial-and-error methods that consume lots of manpower and material resources to match the powder property parameters and powder laying process parameters. In this paper, powder spreading in realistic SLS settings was simulated using a discrete element method (DEM) to investigate the effects of the powder's physical properties and operating conditions on the bed quality, characterized by the density characteristics, density uniformity, and flatness of the powder layer. A regression model of the powdering quality was established based on the response surface methodology (RSM). The relationship between the proposed powdering quality index and the research variables was well expressed. An improved multi-objective optimization algorithm of the non-dominated sorting genetic algorithm II (NSGA-II) was used to optimize the powder laying quality of nylon powder in the SLS process. We provided different optimization schemes according to the different process requirements. The reliability of the multi-objective optimization results for powdering quality was verified via experiments.

Identification of Differentially Expressed microRNAs Associated with Ischemic Stroke by Integrated Bioinformatics Approaches.

Ischemic stroke (IS) is one of the leading causes of disability and mortality worldwide. This study aims to find the crucial exosomal miRNAs associated with IS by using bioinformatics methods, reveal potential biomarkers for IS, and investigate the association between the identified biomarker and immune cell pattern in the peripheral blood of IS patients. In this study, 3 up-regulated miRNAs (hsa-miR-15b-5p, hsa-miR-184, and hsa-miR-16-5p) miRNAs in the serum exosomes between IS patients and healthy controls from GEO database (GSE199942) and 25 down-regulated genes of peripheral blood mononuclear cells of IS patients from GSE22255 were obtained with the help of the R software. GO annotation and KEGG pathway enrichment analysis showed that the 25 down-regulated genes were associated with coenzyme metabolic process and were mainly enriched in the N-glycan biosynthesis pathway. Furthermore, we performed the LASSO algorithm to narrow down the above 25 intersected genes, and identified 8 key genes which had a good diagnostic value in discriminating IS patients from the healthy controls analyzed with ROC curve. CIBERSORT algorithm indicated that the abundance of M0 macrophages and resting mast cells was significantly lower than that of the control group. The spearman correlation analysis showed that STT3A was negatively correlated with the proportion of follicular helper T cells, activated NK cells and resting dendritic cells. Finally, GSE117064 showed that has-miR-16-5p was more advantageous for diagnosing stroke. In conclusion, hsa-miR-15b-5p, hsa-miR-184, and hsa-miR-16-5p are identified as specific related exosomal miRNAs for IS patients. These genes may provide new targets for the early identification of IS.

Drone Assisted Robust Emergency Service Management for Elderly Chronic Disease.

It is important to monitor the early screening of chronic diseases, predict the risk, and provide the comprehensive management of chronic diseases for the elderly. However, it is difficult to provide the robust and real-time emergency service for elderly chronic disease because of the complex social network and diversity of elderly chronic disease service. To address these issues, we design a new drone assisted robust emergency service system. We formulate the Drone assisted Management (DM) problem to minimize the total time cost of drone subject to all elderly chronic disease services which can be guaranteed exactly once by the drone under its energy constraint. Then, we propose the DRS algorithm to solve the DM problem. To provide the robust and real-time service, we further formulate the Charging driven Drone assisted Management (CDM) problem and present the CDRS algorithm to solve the CDM problem. Through the theoretical analysis and numerical simulation experiments, we demonstrate that DRS and CDRS can decrease the total time cost by 37.61% and increase the QoE by 112.80% through the designed system, respectively.

Gambogic Acid Affects Ribosomal Occurrence in Glioma Cells by Downregulating the Phosphoinositide Kinase-3/Protein Kinase B/Mammalian Target of Rapamycin Signaling Pathway.

Gambogic acid (GA) is a natural compound with a polyprenylated xanthone structure that has antiinflammatory, antioxidant, and neuroprotective properties and acts as a chemopreventive agent. GA exhibits anti-tumor, antimicrobial, and anti-proliferative effects on cancer cells. In the current study, the effect of GA on phosphoinositide kinase-3 (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway was examined in human U251 glioma cells. Cell viability and apoptosis were evaluated by MTT and Annexin V/PI Double Staining. The expressions of P38, AKT, and mTOR were evaluated by western blot and qRT-PCR, respectively. MagBeads Total RNA Extraction Kit was used to isolate cell tissue RNA. GA decreased the phosphorylation of P38, AKT, and mTOR. Inhibitors of PI3K (LY294002) enhanced the phosphorylation of P38, AKT, and mTOR. GA reduced the phosphorylation of ribosomal protein precursors (Pre) and upstream binding factor (UBF), and insulin-like growth factor I (IGF-1) further enhanced the cell proliferation and expression of Pre and UBF. These results suggested that downregulation of PI3K/AKT/mTOR signaling pathway may be an important mediator in GA-affected ribosomal occurrence in glioma cells.

Discrete Element Simulation of the Effect of Roller-Spreading Parameters on Powder-Bed Density in Additive Manufacturing.

The powder-bed with uniform and high density that determined by the spreading process parameters is the key factor for fabricating high performance parts in Additive Manufacturing (AM) process. In this work, Discrete Element Method (DEM) was deployed in order to simulate Al2O3 ceramic powder roller-spreading. The effects of roller-spreading parameters include translational velocity Vs, roller's rotational speed ω, roller's diameter D, and powder layer thickness H on powder-bed density were analyzed. The results show that the increased translational velocity of roller leads to poor powder-bed density. However, the larger roller's diameter will improve powder-bed density. Moreover, the roller's rotational speed has little effect on powder-bed density. Layer thickness is the most significant influencing factor on powder-bed density. When layer thickness is 50 µm, most of particles are pushed out of the build platform forming a lot of voids. However, when the layer thickness is greater than 150 µm, the powder-bed becomes more uniform and denser. This work can provide a reliable basis for roller-spreading parameters optimization.

A meta-analysis of caspase 9 polymorphisms in promoter and exon sequence on cancer susceptibility.

BACKGROUND: Caspases are important regulators and executioners in apoptosis pathway and have been defined as either tumor suppressors or oncogenes. Polymorphisms in promoter and exon of caspase 9 were shown to confer genetic susceptibility to multiple cancers, but the results were inconsistent. To accomplish a more precise estimation of the relationship, a meta-analysis was performed. METHODOLOGY/PRINCIPAL FINDINGS: We assessed published studies of the association between caspase 9 polymorphisms and cancer risk from nine studies with 5,528 subjects for rs4645978, six studies with 2,403 subjects for rs105276 and two studies for rs4645981. Overall meta-analysis indicated that no evidence of an association between rs4645978 and cancers was found. Through the stratified analysis, statistically significant reduced cancer risks were observed among Caucasians (AG vs AA: OR = 0.81, 95% CI = 0.66-0.99, P(heterogeneity) = 0.150 and the dominant model: OR = 0.86, 95% CI = 0.75-0.99, P(heterogeneity) = 0.290) and prostate cancer. As for rs105276, Ex5+32G>A polymorphism was found with protective effect in overall meta-analysis (AA vs GG: OR = 0.75, 95% CI = 0.60-0.92, P(heterogeneity) = 0.887; A vs G: OR = 0.85, 95% CI = 0.77-0.95, P(heterogeneity) = 0.739 and the recessive model: OR = 0.68, 95% CI = 0.56-0.82, P(heterogeneity) = 0.309) and Asians group. While for rs4645981, a statistically significant increase in risk of lung cancer was shown in Asians (T vs C: OR = 1.23, 95% CI = 1.07-1.42, P(heterogeneity) = 0.399 and the dominant model: OR = 1.22, 95% CI = 1.04-1.43, P(heterogeneity) = 0.660). CONCLUSIONS/SIGNIFICANCE: Our meta-analysis suggests that the caspase 9 rs4645978 most likely contributes to decreased susceptibility to cancer in Caucasians and prostate cancer. The A allele of rs105276 might be a protective factor for cancer, especially for Asians. However, it seems that rs4645981 confers increased susceptibility to lung cancer in Asians.