Energy harvesting from a rotational transducer under random excitation

This paper evaluates the performance of a proposed device for harvesting energy from the vertical motion of boats and yachts under broadband and band-limited random vibrations. The device comprises a sprung mass coupled to an electrical generator through a ball screw. The mathematical equations describing the dynamics of the system are derived. Then by utilizing the theory of random vibration, the frequency response function of the system is obtained. This is used to derive an expression for the mean power produced by the harvester when it is subjected to broadband and band-limited stationary Gaussian white noise. The power expressions are derived in dimensional form to provide an insightful understanding of the effect of the physical parameters of the system on output power. An expression for the optimum load resistance to harvest maximum power under random excitation is also derived and validated by conducting Monte-Carlo simulation. The discussion presented in the paper provides guidelines for designers to maximize the expected harvested power from a system under broadband and band-limited random excitations. Also, based on the method developed in this paper, the output power of a rotational harvester subjected to the vertical excitation of a sailing boat is obtained

Transplantation of differentiated umbilical cord mesenchymal cells under kidney capsule for control of type I diabetes in rat

Nowadays, stem cells have been introduced as an appropriate source of regenerative medicine for treatment of type I diabetes. Human umbilical cord matrix-derived mesenchymal cells (hUCMC) have successfully been differentiated into insulin producing cells. The isolated hUCM cells were characterized by the expression of stem cell surface markers and by differentiation into adipocytes and osteocytes. The hUCMCs were cultured with different concentrations of neural conditional medium (NCM) and were induced to differentiate into insulin producing cells (IPCs). As 60% NCM concentration resulted in higher nestin and PDX1 expression, the cells were first exposed to 60% NCM and were then induced for IPCs differentiation. PDX1 and insulin gene expression was evaluated in the treated cells. Also, the secretion capacity of the IPCs was assessed by glucose challenge test. IPCs were transferred under the rat kidney capsule. Blood glucose level, weight gain and immunohistochemistry assessments were done in the treated animals. hUCMC expressed mesenchymal cell surface markers and successfully differentiated into adipocytes and osteocytes. Higher NCM concentration resulted in higher PDX1 and nestin expression. The IPCs expressed insulin and PDX1. IPCs were detectable under the kidney capsule 2 months after injection. IPCs transplantation resulted in a sharp decline of blood sugar level and less weight loss. Differentiated hUCM cells could alleviate the insulin deprivation in the rat model of type I diabetes. In addition, higher NCM concentration leads to more differentiation into IPCs and more nestin and PDX1 expression. Kidney capsule can serve as a suitable nominee for IPCs transplantation