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This paper mainly numerically investigates the ultimate compression strength of un-strengthened and CFRP-strengthened steel tubes with random pitting corrosion damage. First, a developed numerical method for steel tubes with random corroded pits is introduced in detail. The accuracy of a similar numerical method is verified through the corresponding experimental measurement and numerical prediction. Then, the ultimate axial compression behavior of steel tubes with random elliptical corroded pits is numerically investigated. Several influencing factors on the ultimate strength of corroded steel tubes under axial compression load are simulated and compared, including different random distributions, region size of corroded pits, number of pits, and depth of pits. Subsequently, the method for strengthening steel tubes by using CFRPs is studied and conducted on the corroded regions of steel tubes. The reliability of steel tubes strengthened by FRP is validated through experimental and numerical results. Finally, the residual compression performance and progressive damage mechanisms of CFRP-strengthened steel tubes are researched. The different parametric influences on the strengthened performance of FRPs are simulated, including layer direction, number of composite layers, and composite materials. The results demonstrate that FRP can improve the axial compression resistance of corroded steel tubes. [ABSTRACT FROM AUTHOR]

Immunocytes dynamically reprogram their gene expression profiles during differentiation and immunoresponse. However, the underlying mechanism remains elusive. Here, we develop a single-cell Hi-C method and systematically delineate the 3D genome and dynamic epigenetic atlas of macrophages during these processes. We propose "degree of disorder" to measure genome organizational patterns inside topologically-associated domains, which is correlated with the chromatin epigenetic states, gene expression, and chromatin structure variability in individual cells. Furthermore, we identify that NF-κB initiates systematic chromatin conformation reorganization upon Mycobacterium tuberculosis infection. The integrated Hi-C, eQTL, and GWAS analysis depicts the atlas of the long-range target genes of mycobacterial disease susceptible loci. Among these, the SNP rs1873613 is located in the anchor of a dynamic chromatin loop with LRRK2, whose inhibitor AdoCbl could be an anti-tuberculosis drug candidate. Our study provides comprehensive resources for the 3D genome structure of immunocytes and sheds insights into the order of genome organization and the coordinated gene transcription during immunoresponse. Here the authors delineate the dynamic changes in 3D genome and epigenome of differentiating macrophages and during infection with Mycobacterium tuberculosis. They reveal a role for NF-κB upon infection and identify SNPs in disease-susceptible loci, including rs1873613 that is located in the anchor of a dynamic chromatin loop. [ABSTRACT FROM AUTHOR]

Foams are substances widely used the foam flooding technology, which aim to greatly improve the residual oil recovery. In the present study, we perform a comprehensive investigation on the oil removal process driven by the foam embedded with magnetic particles, under the action of the magnetic force. The experiment shows that the addition of magnetic particles has little effect on the stability of the foam. During the motion of the foam, its maximum displacement and maximum acceleration are fully explored. Such factors as the volume of the foam, the volume of the oil droplet, the mass concentration of magnetic particles, and the Young's contact angle of surfactant on solid are surveyed in detail. The function curves of the maximum displacement and the maximum acceleration with respect to these variables are obtained in the experiment, and the selection of some optimal parameters is advised. Moreover, the dimensional analysis has been conducted and several scaling laws are given, which are in agreement with the experimental results. These findings are beneficial to understand the oil displacement with the aid of magnetic field, which also provide some inspirations on drug delivery, robots and micro-fluidics. [ABSTRACT FROM AUTHOR]

Circumferentially grooved seals have been widely used in pumps to eliminate outward leakage of rotating liquid. On many occasions, the turbulent flow enhances the drag force on the interface between the liquid and the stator as well as the interface between the liquid and the rotor, creating much higher heat exchange than the conventional thermal conduction in laminar flows. Attention must be paid in the seal design to prevent rapid heating by the seal liquid to the ambient stator. In this study, the geometry of a circumferentially grooved seal is optimized for a better design of thermal insulation as well as reduction in drag force of the seal fluid. For the forward problem, i.e., the hydraulic and thermal analysis of the seal, the theory of bulk flow is used to simplify the thin-film liquid to a two-dimensional field which preserves the average characteristics of the original flow. The method of three-control volume is adopted to partition the liquid into three types of cavity flows. The governing equations of continuity, momentum, and energy transportation are presented for each control volume, and are approximated by the perturbation method and the Fourier expansion. The fluid and thermal solutions by the present perturbation method are validated by a CFD simulation. For the seal optimization, the multi-objective optimization for thermal insulation and drag reduction is converted into an integrated optimization problem with key geometrical parameters of the seal. Response surfaces are generated through radial basis functions to make the constraint functions explicit for the efficiency of the optimization process. The method of moving asymptotes (MMA) is adopted to find the optimized design of the seal geometry with the best performance of thermal insulation and drag reduction of liquid. Examples are presented to demonstrate the effectiveness of the present optimization method. [ABSTRACT FROM AUTHOR]

Topology optimization to minimize the bottom-layer temperature and the structure compliance of the multi-layered thin-walled structure is carried out in this paper. A multi-layered thin-walled structure with improved performances in load-carrying and heat insulation inspired by a species of oceanic gastropods found on a hot and highly pressurized deep-sea floor is proposed. Using genetic algorithm to perform the optimization process, it is proved that the optimal topology under integrated thermal and load conditions is a sandwich structure of three layers similar to the original bionic structure of the oceanic gastropods. Soft layer with good heat insulation is placed as the middle layer, whereas hard layers with fast heat transmission are placed as the top and bottom layers to carry load. The concept of bionic three-layered structure is then applied to the skin design of an airfoil. The analysis for aerodynamic heating of the airfoil with different skin structures shows that the bionic multi-layered structure is an optimal design in both layer thickness and layer sequence. [ABSTRACT FROM AUTHOR]

Purpose: To ascertain the anatomic and radiological parameters of the atlas (C1) pedicle and to explore a preferable method of C1 pedicle screw insertion.Methods: Thirty-four conserved human cadaveric cervical spines (20 males, 14 females) underwent computed tomography (CT) scanning. Trajectories P (perpendicular to the coronal plane) and I (with medial inclination) were designed for each C1 pedicle on CT images. External pedicle wall width, medullary cavity width, transverse angle, and optimal entry point along each trajectory were measured. Cortical screws of 3.5 mm in diameter were inserted into C1 pedicles along trajectory P and I, respectively, and wall perforation was assessed (post-operative CT scanning).Results: The external pedicle wall width and medullary cavity width along trajectory I were significantly wider than trajectory P (P < 0.01). Although external pedicle wall widths were all greater than 3.5 mm, medullary cavity width <3.5 mm was found in 16.1 % pedicles along trajectory P and only 2.9 % along trajectory I. Transverse angle was 21.8° along trajectory I and 0° along trajectory P. Optimal entry point of trajectory I was 4.1 mm lateral from that of trajectory P. The lateral wall perforation rate was significantly lower along trajectory I than trajectory P (P < 0.05).Conclusions: C1 pedicle screw trajectory with medial inclination and more lateral entry points yielded wider medullary cavity width than that perpendicular to the coronal plane, and might minimize lateral wall perforation. [ABSTRACT FROM AUTHOR]

We explored the nature of chromosome 13 loss in cultured human vascular endothelial cells (HUVECs). Chromosome 13 loss detected by metaphase and interphase analysis was noted in earlier passages of HUVEC strains with no relation to telomere length or replicative senescence. Ectopic expression of telomerase did not influence the loss of chromosome 13. HUVECs losing chromosome 13 demonstrated increased migratory potential and loss of heterozygosity. Collectively, these observations suggest that the loss of chromosome 13 gives cultured HUVECs a replicative advantage. [ABSTRACT FROM AUTHOR]