Fluid sloshing in a rigid circular cylindrical tank is investigated; the tank is resting on soil foundation and is excited by horizontal seismic accelerations. A rigid annular baffle is connected to the inner wall of the storage tank to reduce liquid sloshing. By using the fluid subdomain method, the convective velocity potential is derived. An equivalent model with mass-spring oscillators is proposed to describe the sloshing motions of the contained liquid. Then, by means of the least square method, a complex polynomial fraction is employed to fit the dynamic impedance of the soil. A nested lumped parameter model is established to model the effect of the soil foundation. The substructure method allows to obtain the soil–tank–liquid coupled model. The equation of motion of the coupled system is solved by the Newmark-[Formula: see text] method. A comparison between the present sloshing results and those published in the literature shows an excellent agreement. The effects of the soil parameters, the baffle position and its size on the dynamic behavior of the soil–tank–liquid system are discussed in detail. The results demonstrate that the soil properties and the baffle parameters can have a remarkable influence on liquid sloshing. The novelty of this research is that an analytical model for the soil–tank–liquid–baffle coupled system is derived for the first time and it allows to study the dynamics and sloshing response of the system with accuracy and low computational cost.
Background
Natronobacterium gregoryi Argonaute (NgAgo) was found to reduce mRNA without generating detectable DNA double-strand breaks in a couple of endogenous genes in zebrafish, suggesting its potential as a tool for gene knockdown. However, little is known about how it interacts with nucleic acid molecules to interfere with gene expression.
Results
In this study, we first confirmed that coinjection of NgAgo and gDNA downregulated target genes, generated gene-specific phenotypes and verified some factors (including 5’ phosphorylation, GC ratio, and target positions) of gDNAs affecting gene downregulation. Therein, the sense and antisense gDNAs were equally effective, suggesting that NgAgo possibly binds to DNA. NgAgo-VP64 with gDNAs targeting promoters upregulated the target genes, further providing evidence that NgAgo interacts with genomic DNA and controls gene transcription. Finally, we explain the downregulation of NgAgo/gDNA target genes by interference with the process of gene transcription, which differs from that of morpholino oligonucleotides.
Conclusions
The present study provides conclusions that NgAgo may target genomic DNA and that target positions and the gDNA GC ratio influence its regulation efficiency.
In this study, the liquid sloshing in a cylindrical tank considering soil–structure interaction and undergoing horizontal excitation is investigated analytically. Multiple rigid annular baffles are positioned on the rigid wall to mitigate the liquid sloshing. Firstly, combined with the subdomain partition method for sloshing, the complex liquid domain is partitioned into simple subdomains with the single condition for boundary. Based on continuity conditions of velocity and pressure as well as the linear sloshing equation for free surface, the exact solution for convective velocity potential is derived with high accuracy. By yielding the similar hydrodynamic shear and moment as those of the original system, a mechanical model is developed to describe continuous sloshing, and parameters of the model are given in detail. Then, by means of the least squares approach, the Chebyshev polynomials are utilized to fit impedances for the circular surface foundation. A lumped parameter model is employed to represent influences of soil on the superstructure. Finally, by using the substructure method, a coupling model of the soil–tank system is developed to simplify the dynamic analysis. Comparison investigations are carried out to verify the effectiveness of the model. Detailed sloshing characteristics and dynamic responses of sloshing are analyzed with regard to different baffle sizes and positions as well as soil parameters, respectively. The novelty of the present study is that an equivalent analytical model for the soil–foundation–tank–liquid system with multiple baffles is firstly obtained and it allows the dynamic behaviors of the coupling system to be investigated with high computation efficiency and acceptable accuracy.
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