For the rolling element bearing-rotor system, the bearing stiffness and eventual system vibration performance are influenced by the shape and position errors of the bearing housing. In this article, a rotor supported by two cylindrical roller bearings is investigated. The load and deformation between the roller and the raceways of the bearing and the bending deformation of the rotor are analysed. An analytical model is established for calculating the radial and angular stiffnesses of the bearing considering the bearing housing deflections. Consequently, a vibration model which can consider the influences of the bearing housing deflections is developed for the bearing-rotor system. With a calculation example, the influences of the housing deflection angles on the vibration performance of the bearing-rotor system are studied numerically and a series of conclusions are obtained and explained.

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Based on a set of formulae for calculating elliptical contact parameters and elastic deformation developed by Houpert and mechanical analysis, a numerical model is established for calculating the roller load distribution and shaft axis orbit of spherical roller bearings with considering off-sized rollers in this paper. A numerical calculation example is carried out to investigate the effects of single off-sized roller and multiple off-sized rollers on spherical roller bearing roller load distribution and axis orbit. Results show that the roller maximum load will increase as its off-sized diameter becomes larger than the nominal diameter, and the roller maximum load will decrease as its off-sized diameter is smaller than the nominal diameter. The maximum loads of the rollers in the two rows neighboring on the off-sized roller/rollers can also be affected. Meanwhile, roller diameter error will largely affect the axis orbit and inner ring radial displacement of spherical roller bearings.

Recombinant therapeutic proteins (RTPs) are important parts of biopharmaceuticals. Chinese hamster ovary cells (CHO) have become the main cell hosts for the production of most RTPs approved for marketing because of their high-density suspension growth characteristics, and similar human post-translational modification patterns et al. In recent years, many studies have been performed on CHO cell expression systems, and the yields and quality of recombinant protein expression have been greatly improved. However, the expression levels of some proteins are still low or even difficult-to express in CHO cells. It is urgent further to increase the yields and to express successfully the “difficult-to express” protein in CHO cells. The process of recombinant protein expression of is a complex, involving multiple steps such as transcription, translation, folding processing and secretion. In addition, the inherent characteristics of molecular will also affect the production of protein. Here, we reviewed the factors affecting the expression of recombinant protein and improvement strategies in CHO cells.

The key requirement to calculate the fatigue and wear levels of wheels and rails is to establish a method that can accurately represent the wheel/rail contact stress. Wheel and rail surfaces are composed of a series of surfaces each with a different curvature, which makes research on wheel/rail contact very difficult. In this paper, a wheel from a passenger train with a LM-type worn tread profile and a 60 kg/m rail are taken as the research objects in a study on the contact positions and static contact stress. An analytical model for accurately finding the contact position is established by building and solving wheel and rail profile equations. Furthermore, a slice-based model is established to calculate the contact stress of a contact point, especially for points on the profiles near the junction of two surfaces with different curvatures. The error created by using the slice-based model is corrected so as to make the calculation more accurate. An example, in which the axis load is 18 t, is analyzed. The maximum contact stress, deformation and contact spot size are calculated, and some useful conclusions are obtained. The research presented in this paper can provide a reliable foundation for future research on wheel and rail fatigue, friction and wear.