Long-Term Maintenance and Meiotic Entry of Early Germ Cells in Murine Testicular Organoids Functionalized by 3D Printed Scaffolds and Air-Medium Interface Cultivation

Short-term germ cell survival and central tissue degeneration limit organoid cultures. Here, testicular organoids (TOs) were generated from two different mouse strains in 3D printed one-layer scaffolds (1LS) at the air-medium interface displaying tubule-like structures and Leydig cell functionality supporting long-term survival and differentiation of germ cells to the meiotic phase. Chimeric TOs, consisting of a mixture of primary testicular cells and EGFP+ germline stem (GS) cells, were cultured in two-layer scaffolds (2LSs) for better entrapment. They showed an improved spheroidal morphology consisting of one intact tubule-like structure and surrounding interstitium, representing the functional unit of a testis. However, GS cells did not survive long-term culture. Consequently, further optimization of the culture medium is required to enhance the maintenance and differentiation of germ cells. The opportunities TOs offer to manipulate somatic and germ cells are essential for the study of male infertility and the search for potential therapies.

Development of an improved mathematical model for the dynamic response of a sphere located at a viscoelastic medium interface

A comprehensive investigation on the static and dynamic responses of a sphere located at elastic and viscoelastic medium interfaces is performed in this study. First, the mathematical models commonly used for predicting the static displacement of a sphere located at an elastic medium interface are presented and their performances are compared. After that, based on the finite element analyses, an accurate mathematical model to predict the static displacement of a sphere located at an elastic medium interface valid for different Poisson’s ratios of the medium and small and large sphere displacements is proposed. Then, an improved mathematical model for the dynamic response of a sphere located at a viscoelastic medium interface is developed. In addition to the Young’s modulus of the medium and the radius of the sphere, the model takes into account the density, Poisson’s ratio and viscosity of the medium, the mass of the sphere and the radiation damping. The effects of the radiation damping, the Young’s modulus, density and viscosity of the medium and the density of the sphere on the dynamic response of the sphere located at a viscoelastic medium interface are explored. The developed model can be used to understand the dynamic responses of spherical objects located at viscoelastic medium interfaces in practical applications. Furthermore, the proposed model is a significant tool for graduate students and researchers in the fields of engineering, materials science and physics to gain insight into the dynamic responses of spheres located at viscoelastic medium interfaces.

Development of an iPad-based assessment tool for measuring attention and validation in older employees

BACKGROUND: In recent years, the elderly population has increasingly worked in various workplaces. Hence, measurements to assess the work attention of the elderly has become an important need. OBJECTIVES: The aims of this research project are to develop an iPad-based attention assessment tool, “Shih-Hsu Test of Attention” (SHTA) for work attention, that adopts touchscreen as the medium interface, and to explore criterion-related validity and test-retest reliability of this new attention assessment tool for elders. METHODS: Thirty-one participants aged between 65–85 years were recruited in this study on a voluntary basis. Each participant was assessed two times. The participants completed both the SHTA and Chu’s Attention Test (CAT), and the SHTA was used to test participants after three weeks. RESULTS: The analytical results demonstrate that the SHTA has acceptable criterion-related validity (γ= 0.400, p < 0.05*) and test-retest reliability (ICC = 0.920, p < 0.01**). CONCLUSIONS: Our preliminary findings show that the iPad-based auditory attention assessment tool, SHTA, has satisfactory criterion-related validity and test-retest reliability, which supports the use of SHTA as an attention assessment tool for older employees.

The extracellular juncture domains in the intimin passenger adopt a constitutively extended conformation inducing restraints to its sphere of action

Enterohemorrhagic and enteropathogenic Escherichia coli are among the most important food-borne pathogens, posing a global health threat. The virulence factor intimin is essential for the attachment of pathogenic E. coli to the intestinal host cell. Intimin consists of four extracellular bacterial immunoglobulin-like (Big) domains, D00–D2, extending into the fifth lectin subdomain (D3) that binds to the Tir-receptor on the host cell. Here, we present the crystal structures of the elusive D00–D0 domains at 1.5 Å and D0–D1 at 1.8 Å resolution, which confirms that the passenger of intimin has five distinct domains. We describe that D00–D0 exhibits a higher degree of rigidity and D00 likely functions as a juncture domain at the outer membrane-extracellular medium interface. We conclude that D00 is a unique Big domain with a specific topology likely found in a broad range of other inverse autotransporters. The accumulated data allows us to model the complete passenger of intimin and propose functionality to the Big domains, D00–D0–D1, extending directly from the membrane.

Обратная волна Ценнека вдоль плоской границы раздела сред

We consider the surface Zennek wave along the plane boundaries of the vacuum-medium interface with isotropic permittivity, and the vacuum-medium described by isotropic dielectric and magnetic permittivity. In the latter case, we also consider the H-wave and the possibility of negative real parts of the permeability. Forward and backward waves at the boundary of a material with an inhomogeneous permittivity profile are considered. The conditions for the existence of forward and backward surface and volume waves, as well as fast and slow surface waves, are studied.