A review of high-speed electro-hydrostatic actuator pumps in aerospace applications: challenges and solutions

The continued development of electro-hydrostatic actuators (EHAs) in aerospace applications has put forward an increasing demand upon EHA pumps for their high power density. Besides raising the delivery pressure, increasing the rotational speed is another effective way to achieve high power density of the pump, especially when the delivery pressure is limited by the strength of materials. However, high-speed operating conditions can lead to several challenges to the pump design. This paper reviews the current challenges including the cavitation, flow and pressure ripples, tilting motion of rotating group and heat problem, associated with a high-speed rotation. In addition, potential solutions to the challenges are summarized, and their advantages and limitations are analyzed in detail. Finally, future research trends in EHA pumps are suggested. It is hoped that this review can provide a full understanding of the speed limitations for EHA pumps and offer possible solutions to overcome them

4,4′-Bipyridine–pyridine-3,5-dicarb­oxy­lic acid (3/4)

In the title compound, 3C10H8N2·4C7H5NO4, the asymmetric unit contains two mol­ecules of pyridine-3,5-dicarb­oxy­lic acid and one mol­ecule of 4,4′-bipyridine in general positions together with one mol­ecule of 4,4′-bipyridine lying across a centre of inversion, thus giving a 4:3 molar ratio of pyridine-3,5-dicarb­oxy­lic acid to 4,4′-bipyridine. The dihedral angle between the bipyridine rings on general positions is 21.2 (2)°. These mol­ecular units are linked by O—H⋯N hydrogen bonds forming an extended two-dimensional framework in the crystal

Novel three-piston pump design for a slipper test rig

Slipper's micro motions including the squeezing motion, spinning motion, and tilting motion have a significant impact on its lubricating condition and dynamic behavior. However, few experimental studies are on these micro motions within a real axial piston pump, especially the slipper's spinning motion. The experimental investigations on the slipper in the past mainly focused on the parameters of the oil film such as pressure, thickness, and temperature. The sensors were often installed in the fixed swash plate when the cylinder block was chosen to rotate. Alternatively, the sensors were mounted in the fixed modified slipper when the swash plate rotated. The biggest challenge of the direct measurements of these micro motions is the space limitation for the sensor installation due to the compact structure of axial piston pumps as well as the slipper's macro motion. This paper presents a new three-piston pump for the slipper test rig which can provide enough installation space for the sensor. To realize the cylinder block balance, a hold-down plate is first introduced into this three-piston pump. In addition, a detailed set of relevant equations is derived to evaluate the functionality of the hold-down plate. Finally, the slipper's spinning motion was measured directly and continuously using this three-piston pump, which confirmed the capability of the slipper test rig

Bis[4-(2-aza­niumyleth­yl)piperazin-1-ium] di-μ-sulfido-bis­[disulfido­germanate(II)]

In the title compound, (C6H17N3)2[Ge2S6], the dimeric [Ge2S6]4− anion is formed by two edge-sharing GeS4 tetra­hedral units. The average terminal and bridging Ge—S bond lengths are 2.164 (2) and 2.272 (8) Å, respectively. The dimeric inorganic anions and the organic piperazinium cations are organized into a three-dimensional network by N—H⋯S hydrogen bonds

Ferrocenyl­phospho­nic acid

In the title compound, [Fe(C5H5)(C5H6O3P)], the phosphate group is bonded to the ferrocene unit with a P—C bond length of 1.749 (3) Å. In the crystal, six ferrocenyl­phospho­nic acid mol­ecules are connected by 12 strong inter­molecular O—H⋯O hydrogen bonds, leading to the formation of a highly distorted octa­hedral cage. The volume of the octa­hedral cage is about 270 Å3

1,4-Bis(3-pyridylmethyl­eneamino­meth­yl)benzene

The title compound, C20H18N4, is a flexible 3,3′-bipyridyl-type ligand with a long spacer group between the two pyridyl functions. The mol­ecule crystallizes around an inversion center, with one half-mol­ecule in the asymmetric unit and a dihedral angle of 71.85 (8)° between the pyridine ring and the central benzene ring

1,4-Bis(2-pyridylmethyl­eneamino­meth­yl)benzene

The asymmetric unit of the centrosymmetric title compound, C20H18N4, contains one half-mol­ecule. The pyridine and benzene rings are oriented at a dihedral angle of 77.21 (7)°

Molecular Mechanisms of Hepatocellular Carcinoma Related to Aflatoxins: An Update

Hepatocellular carcinoma (hepatocarcinoma) is a major type of primary liver cancer and one of the most frequent human malignant neoplasms. Aflatoxins are I-type chemical carcinogen for hepatocarcinoma. Increasing evidence has shown that hepatocarcinoma induced by aflatoxins is the result of interaction between aflatoxins and hereditary factor. Aflatoxins can induce DNA damage including DNA strand break, adducts formation, oxidative DNA damage, and gene mutation and determine which susceptible individuals feature cancer. Inheritance such as alterations may result in the activation of proto-oncogenes and the inactivation of tumor suppressor genes and determine individual susceptibility to cancer. Interaction between aflatoxins and genetic susceptible factors commonly involve in almost all pathologic sequence of hepatocarcinoma: chronic liver injury, cirrhosis, atypical hyperplastic nodules, and hepatocarcinoma of early stages. In this review, we discuss the biogenesis, toxification, and epidemiology of aflatoxins and signal pathways of aflatoxin-induced hepatocarcinoma. We also discuss the roles of some important genes related to cell apoptosis, DNA repair, drug metabolism, and tumor metastasis in hepatocarcinogenesis related to aflatoxins