Research on unsteady performance of a two-stage self-priming centrifugal pump

In order to study the unsteady performance of a two-stage self-priming centrifugal pump, the unsteady numerical calculation in a two-stage self-priming centrifugal pump was performed and energy characteristics experiments and self-priming experiments were carried out. The pressure pulsation and radial force in the pump were then analyzed. The results show that numerical calculation values are close to the experiment values. Head deviation of the pump is less than 3 %, and efficiency deviation of the pump is less than 2 percentage points. Compared with monitoring point P1, the pressure fluctuation coefficient of monitoring point P3 at the design flow rate is reduced by 61 %. Compared with monitoring point P8, the pressure fluctuation coefficient of monitoring point P5 is reduced by 70 %. The radial force on the radial guide-vane is obviously smaller than that on the volute. Under the same flow rate, radial force on the volute of second-stage pump is almost 20 times larger than that on the radial guide-van of first-stage pump

Effect of suction chamber baffles on pressure fluctuations in a low specific speed centrifugal pump

In order to study the effect of suction chamber baffles on hydraulic performance and unsteady characteristics in a low specific speed centrifugal pump, a model pump was design with enlarging flow mothed and four schemes of suction baffle, including no baffle (scheme 0), only one baffle in the suction (scheme 1), two baffles (scheme 2) and three baffles in the suction (scheme 3), were considered. Commercial code FLUENT was applied to simulate the flow of the pump. RNG k-ε turbulence model was adopted to handle with the turbulent flows in the pump. The sliding mesh technique was applied to take into account the impeller-volute interaction. Based on the simulation results, the hydraulic performance and pressure fluctuations were obtained and analyzed in detail. The head value of no baffle in the suction (scheme 0) is lower than that with baffles in the suction (scheme 1, scheme 2, scheme 3) at each condition point. Hump point in scheme 0 is at φ= 0.00596 (1.2 times Qo). The hump point in scheme 1, scheme 2, scheme 3 is at 0.8Qo, 1.0Qo, 1.0Qo, respectively. The ε value of scheme 1 is the smallest and that of scheme 0 is the largest in the four schemes. Six wave troughs are observed clearly at each monitoring point as the impeller rotates in a circle. Each time the impeller is turned 10 degrees, there are six obvious troughs around the impeller. With the rotation of the impeller, peak value of pressure fluctuations at blade passing frequency (BPF) is gradually decrease. At low flow (ϕ= 0.002383), the main frequency of pressure fluctuation at P36 and P1 under scheme 0, scheme 2 and scheme 3 is 295 Hz, which is corresponding to BPF. The pressure fluctuation levels are decreased by –2.72 %, –2.13 %, and –2.21 % respectively when the number of baffle in the suction is one, two, three, respectively. And decrease rate of pressure fluctuation (∆Cp) on scheme 1 is maximum. It indicates that Adding baffles to the suction chamber is beneficial to reduce the amplitude of pressure pulsation at BPF in the volute. The best number of baffles in the suction is one. Based on scheme 1 simulation results, the prototype was manufactured and the performance experiments were carried out. A good agreement of the head and efficiency between numerical results and experimental results are observed

Members of the Arabidopsis thaliana FL family act with ARF machinery to localize PIN1 during auxin related developmental processes

PINFORMED (PIN) proteins are phytohormone auxin efflux carriers. By polar distribution and dynamic re-localization via the endomembrane vesicle trafficking system, PIN proteins control many auxin-dependent developmental processes. Vesicle trafficking is controlled by protein machineries including small G protein ADP ribosylation factors (ARFs) and their regulators ARF-GTPase activating proteins (ARF-GAPs) and ARF-guanine nucleotide exchange factors (ARF-GEFs). FORKED1 (FKD1) is part of the nine member Arabidopsis FKD1-LIKE (FL) gene family. My results show that FKD1 and SCARFACE (SFC/FKD2, an ARF-GAP) co-localize with BIGs (ARF-GEFs) and they all co-localize with PIN1 in vesicles. Mutant analysis supports the idea that FKD1, SFC and BIGs are acting in the same secretory pathway, and together with ARFA group, these proteins control PIN1 localization and therefore the auxin transport in leaves, hypocotyls and roots. My results also show that FL3 is acting in a different manner from FKD1, likely in the endocytic pathway.NSERC Discovery Gran

Research on pressure fluctuation characteristics of a centrifugal pump with guide vane

In order to study the pressure pulsation characteristics of a centrifugal pump with a guide vane, a pump with specific speed ns= 190 was chosen as the research object. The numerical simulation was carried out using the standard k-ε turbulence model. The pressure pulsation characteristic was researched at a set monitoring point. The reliability of the numerical simulation was verified with experiment results. The pressure pulsation characteristic curves of each calculation domain were obtained by dimensionless data processing. The results elucidate that the rotor/stator interaction at the outlet of the impeller is the main source for the pressure pulsation. With increasing distance, the pressure pulsation gradually decreases; the pressure pulsation amplitude of the pressure surface is larger than the suction surface; the pressure pulsation in the flow channel of the guide vane remains the same; the pressure fluctuation near the outlet of the annular volute chamber is larger, and the pressure pulsation near the upstream of the flow channel is quite complicated. The pressure pulsation at the annular volute and axial symmetry is the same

Metatranscriptomic Comparison of Endophytic and Pathogenic \u3cem\u3eFusarium\u3c/em\u3e-Arabidopsis Interactions Reveals Plant Transcriptional Plasticity

Plants are continuously exposed to beneficial and pathogenic microbes, but how plants recognize and respond to friends versus foes remains poorly understood. Here, we compared the molecular response of Arabidopsis thaliana independently challenged with a Fusarium oxysporum endophyte Fo47 versus a pathogen Fo5176. These two F. oxysporum strains share a core genome of about 46 Mb, in addition to 1,229 and 5,415 unique accessory genes. Metatranscriptomic data reveal a shared pattern of expression for most plant genes (about 80%) in responding to both fungal inoculums at all timepoints from 12 to 96 h postinoculation (HPI). However, the distinct responding genes depict transcriptional plasticity, as the pathogenic interaction activates plant stress responses and suppresses functions related to plant growth and development, while the endophytic interaction attenuates host immunity but activates plant nitrogen assimilation. The differences in reprogramming of the plant transcriptome are most obvious in 12 HPI, the earliest timepoint sampled, and are linked to accessory genes in both fungal genomes. Collectively, our results indicate that the A. thaliana and F. oxysporum interaction displays both transcriptome conservation and plasticity in the early stages of infection, providing insights into the fine-tuning of gene regulation underlying plant differential responses to fungal endophytes and pathogens

Fungal volatile organic compounds: mechanisms involved in their sensing and dynamic communication with plants

Microbial volatile organic compounds (MVOCs) are mixtures of gas-phase hydrophobic carbon-based molecules produced by microorganisms such as bacteria and fungi. They can act as airborne signals sensed by plants being crucial players in triggering signaling cascades influencing their secondary metabolism, development, and growth. The role of fungal volatile organic compounds (FVOCs) from beneficial or detrimental species to influence the physiology and priming effect of plants has been well studied. However, the plants mechanisms to discern between FVOCs from friend or foe remains significantly understudied. Under this outlook, we present an overview of the VOCs produced by plant-associate fungal species, with a particular focus on the challenges faced in VOCs research: i) understanding how plants could perceive FVOCs, ii) investigating the differential responses of plants to VOCs from beneficial or detrimental fungal strains, and finally, iii) exploring practical aspects related to the collection of VOCs and their eco-friendly application in agriculture

Vision, challenges and opportunities for a Plant Cell Atlas

With growing populations and pressing environmental problems, future economies will be increasingly plant-based. Now is the time to reimagine plant science as a critical component of fundamental science, agriculture, environmental stewardship, energy, technology and healthcare. This effort requires a conceptual and technological framework to identify and map all cell types, and to comprehensively annotate the localization and organization of molecules at cellular and tissue levels. This framework, called the Plant Cell Atlas (PCA), will be critical for understanding and engineering plant development, physiology and environmental responses. A workshop was convened to discuss the purpose and utility of such an initiative, resulting in a roadmap that acknowledges the current knowledge gaps and technical challenges, and underscores how the PCA initiative can help to overcome them.</jats:p

Differential Colonization of the Plant Vasculature Between Endophytic Versus Pathogenic Fusarium oxysporum Strains

Plant xylem colonization is the hallmark of vascular wilt diseases caused by phytopathogens within the Fusarium oxysporum species complex. Recently, xylem colonization has also been reported among endophytic F. oxysporum strains, resulting in some uncertainty. This study compares xylem colonization processes by pathogenic versus endophytic strains in Arabidopsis thaliana and Solanum lycopersicum, using Arabidopsis pathogen Fo5176, tomato pathogen Fol4287, and the endophyte Fo47, which can colonize both plant hosts. We observed that all strains were able to advance from epidermis to endodermis within 3 days postinoculation (dpi) and reached the root xylem at 4 dpi. However, this shared progression was restricted to lateral roots and the elongation zone of the primary root. Only pathogens reached the xylem above the primary-root maturation zone (PMZ). Related to the distinct colonization patterns, we also observed stronger induction of callose at the PMZ and lignin deposition at primary-lateral root junctions by the endophyte in both plants. This observation was further supported by stronger induction of Arabidopsis genes involved in callose and lignin biosynthesis during the endophytic colonization (Fo47) compared with the pathogenic interaction (Fo5176). Moreover, both pathogens encode more plant cell wall–degrading enzymes than the endophyte Fo47. Therefore, observed differences in callose and lignin deposition could be the combination of host production and the subsequent fungal degradation. In summary, this study demonstrates spatial differences between endophytic and pathogenic colonization, strongly suggesting that further investigations of molecular arm-races are needed to understand how plants differentiate friend from foe. [Graphic: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license

Optimization Research on the Space-V-Type Biomimetic Surface Grooves of a Marine Centrifugal Pump

The biomimetic surface with Space-V grooves can effectively reduce flow resistance and noise. Our investigation was in order to further enhance the drag reduction and noise reduction performance of a marine centrifugal pump with Space-V-groove-shaped biomimetic surfaces. A regression equation was established with response surface methodology between the total sound pressure level and the height (h), width (s), and spacing (b) of the biomimetic groove structure. The interaction effects of various parameters on the total sound pressure level were analyzed, and the parameter range was determined at the lowest total sound pressure level. The hydraulic performance and interior noise of the model before and after optimization were compared. The results showed that the total sound pressure level initially decreased and then increased with increasing groove height. Similarly, with an increase in groove width, the total sound pressure level decreased at first, then increased. When the height of the bionic groove is 0.5–0.7 mm, the groove width is 0.4–0.7 mm, the groove spacing is 0.7–1.3 mm, and the total sound pressure level of the centrifugal pump is the smallest, which is 180–182 dB. On the other hand, the total sound pressure level increased as groove spacing increased. Through the use of an optimized Space-V groove model, under rated working conditions, the model head is increased by 0.27 m and the efficiency is increased by 1.21%. In addition, the optimized model has excellent drag and noise reduction performance, with the drag reduction rate of 3.73% and noise reduction rate of 1.81%, which are, respectively, increased by 0.87% and 0.45% compared with before optimization. The performance of centrifugal pumps for ships can be greatly improved