Rho-dependent control of the Citron kinase, Sticky, drives midbody ring maturation

Rho-dependent proteins control assembly of the cytokinetic contractile ring, yet it remains unclear how those proteins guide ring closure and how they promote subsequent formation of a stable midbody ring. Citron kinase is one important component required for midbody ring formation but its mechanisms of action and relationship with Rho are controversial. Here, we conduct a structure–function analysis of the Drosophila Citron kinase, Sticky, in Schneider’s S2 cells. We define two separable and redundant RhoGEF/Pebble-dependent inputs into Sticky recruitment to the nascent midbody ring and show that each input is subsequently required for retention at, and for the integrity of, the mature midbody ring. The first input is via an actomyosin-independent interaction between Sticky and Anillin, a key scaffold also required for midbody ring formation. The second input requires the Rho-binding domain of Sticky, whose boundaries we have defined. Collectively, these results show how midbody ring biogenesis depends on the coordinated actions of Sticky, Anillin, and Rho.

Prediction of Low-Engine-Order Excitation due to a Non-Symmetrical Nozzle Ring in a Radial Turbine by Means of the Nonlinear Harmonic Approach

Low engine order (LEO) excitation in a turbomachine stage can be induced by non-uniform inflow conditions, manufacturing tolerances or in-service wear. LEOs are known to excite significant forced response vibration amplitudes that can easily cause High Cycle Fatigue (HCF) failure of blades. The accurate prediction of LEO excitation usually requires high-fidelity CFD models of the full annulus of the machine due to the loss of symmetry leading to excessive computational cost. Previous investigation showed that the aerodynamic excitation stemming from the blade-passing-frequency in a vaned radial inflow turbine can be accurately predicted by using the NonLinear Harmonic (NLH) method at highly reduced computational costs. In the current paper, the feasibility of the NLH method for the prediction of LEO excitation due to geometrical asymmetries is investigated for the same test object. An exact digital replica of the nozzle guide ring is created using measured throat width data. NLH simulations resolving different combinations of frequencies and a time-marching calculation are conducted with the new model involving this digital replica. The results show that a NLH model including small number of certain frequencies is able to predict the occurring LEO excitation sufficiently accurate. By comparing results from subsequent forced response analysis with measured vibration amplitudes, a satisfactory agreement was found confirming this conclusion.

Rho-dependent control of the Citron kinase, Sticky, drives midbody ring maturation

Rho-dependent proteins control assembly of the cytokinetic contractile ring (CR), yet it remains unclear how those proteins guide ring closure and how they promote subsequent formation of a stable midbody ring (MR). Citron kinase is one important component required for MR formation but its mechanisms of action and relationship with Rho are controversial. Here, we conduct a structure-function analysis of the Drosophila Citron kinase, Sticky, in Schneider’s S2 cells. We define two separable and redundant RhoGEF/Pebble-dependent inputs into Sticky recruitment to the nascent MR and show that each input is subsequently required for retention at, and for the integrity of, the mature MR. The first input is via an actomyosin-independent interaction between Sticky and Anillin, a key scaffold also required for MR formation. The second input requires the Rho-binding domain of Sticky, whose boundaries we have defined. Collectively, these results show how MR biogenesis depends on the coordinated actions of Sticky, Anillin and Rho.

Service Temperature Evaluation of Cast K465 Superalloy Turbine Vane Based on Microstructural Evolution

The overtemperature in a vane made of cast K465 superalloy is investigated in this paper. The vane was taken from a K465 guide ring after the service for specific period of time. The relationship between the temperature and content of γ´ precipitates was established for the K465 superalloy, which was then used to make the microstructural evolution analysis on failed turbine vane associated with overtemperature. The content of γ´ precipitates in dendritic region and the volume fraction of melting zone in interdendritic region in K465 superalloy were used as the microstructural parameters to check the overtemperature. It is found that there is a sound relationship between the parameters and the temperature. On the basis of this relationship, the microstructural evolution along with temperature variation of the overtemperature K465 turbine vane can be analyzed and the overall service temperature which the K465 guide ring experienced can be evaluated.

Influence of Guide Ring on Energy Loss in a Multistage Centrifugal Pump

Multistage centrifugal pumps are highly efficient and compact in structure. Pump efficiency can be improved by an effective understanding of hydraulic behavior and energy loss, however, the traditional hydraulic loss evaluation method does not readily reveal the specific locations of energy loss in the pump. In this study, a guide ring was imposed in multistage pumps, and an entropy production theory was applied to investigate irreversible energy loss of a multistage pump with and without guide ring. Detailed distributions of energy losses in the pumps were calculated to determine the respective entropy production rates (EPRs). The EPR values as calculated are in close accordance with actual hydraulic loss values in the pumps. EPR values were higher in the multistage pump with the guide ring than the pump without a guide ring under part-load flow conditions (0.2Qd). However, the vortex flow in the pump was weakened (or eliminated) by the guide ring as flow rate increased; this reduced energy loss in the chambers. Flow passing the chamber was stabilized by the guide ring, which decreased shock and vortex loss in the chamber and guide vane. Under both designed flow condition and overload conditions, the EPR values of the guide ring-equipped multistage pump were lower than those without the guide ring. Furthermore, minimum efficiency index (MEI) values were also calculated for the two chamber structures; it was found that overall efficiency of pump with guide ring is better than that without.

Description of Longidorus cheni sp. n. (Nematoda, Longidoridae) from China

Longidoruschenisp. n., an amphimictic species recovered from the rhizosphere ofLarixprincipis-rupprechtiiandPyracanthafortuneanain Shanxi and Beijing, China, is described and illustrated. The taxonomic position ofL.chenisp. n.among other species within the genus was elucidated using morphometric and molecular data, and phylogenetic relationships were inferred using D2–D3 expansion domains of 28S and 18S rRNA genes by Bayesian Inference (BI) method. The new species is characterised by females with a medium body size (L = 4.9–6.6 mm), a lip region slightly expanded, broadly rounded frontally and laterally, the amphidial fovea broad and symmetrically bilobed at base, odontostyle long and slender (143–168 μm), odonthophore slightly swollen at the base, tail short bluntly conoid to rounded. Guide ring located far posterior from the oral aperture (70–93 μm). Males with two ad-cloacal pairs of supplements preceded by a row of 10–14 ventromedian supplements, with robust spicules measuring 111–126 μm along the median line. Three juvenile stages were present, tail shape of J1 elongate conoid while in J2 and J3 the tail gradually becomes bluntly rounded. Codes for identifying the new species are: A6-B3-C5-D2-E2-F3-G1-H1-I2-J2-K2.Longidoruschenisp. n.belongs to a group of species with a guide ring at the mid-odontostyle position that have a predominantly Asiatic origin. It differs from all of them by a combination of morphological characters and unique sequences of partial 18S and D2–D3 region of 28S rRNA genes. The percentage dissimilarities in partial 18S and D2–D3 28S rRNA genes ofL.chenito the closest species (L.litchii,L.fangi,L.jonesiandL.juglans) were 1.5 %–1.8 % and 16.8–18.3 %, respectively.

Morphological and molecular characterisation of Longidorus pinus sp. n. (Nematoda: Longidoridae) from China and a key to known species of Longidorus in China

Summary Longidorus pinus sp. n. from China is characterised by females 3.3-4.9 mm long; lip region 8-12 μm diam., distinctly offset by a constriction; amphidial fovea pocket-shaped without basal lobes; a short odontostyle (67-81 μm); anteriorly located guide ring (30-38 μm); and short and conoid tail (31-40 μm long, c = 84-138, c′ = 1.2-1.9), with one or two pairs of caudal pores on each side. Males were not found. Three developmental juvenile stages were identified, the first-stage juvenile with conoid tail (c′ = 2.4-2.9). The polytomous key codes for the new species are: A2(3), B1, C23, D4, E1, F2, G23, H23, I1, J2, K6. Molecular phylogenetic analyses based on SSU, D2-D3 of LSU, ITS1 and ITS2 rDNA sequences indicate that L. pinus sp. n. is closely related to L. hangzhouensis, L. asiaticus, and L. camelliae, all of which apparently share a common Asiatic geographic origin. In addition, a key for identification of Longidorus found in China, based on morphological characters of both female and first-stage juvenile, is provided.