Endothelial Progenitor Cells Promote Directional Three-Dimensional Endothelial Network Formation by Secreting Vascular Endothelial Growth Factor

Endothelial progenitor cell (EPC) transplantation induces the formation of new blood-vessel networks to supply nutrients and oxygen, and is feasible for the treatment of ischemia and cardiovascular diseases. However, the role of EPCs as a source of proangiogenic cytokines and consequent generators of an extracellular growth factor microenvironment in three-dimensional (3D) microvessel formation is not fully understood. We focused on the contribution of EPCs as a source of proangiogenic cytokines on 3D microvessel formation using an in vitro 3D network model. To create a 3D network model, EPCs isolated from rat bone marrow were sandwiched with double layers of collagen gel. Endothelial cells (ECs) were then cultured on top of the upper collagen gel layer. Quantitative analyses of EC network formation revealed that the length, number, and depth of the EC networks were significantly enhanced in a 3D model with ECs and EPCs compared to an EC monoculture. In addition, conditioned medium (CM) from the 3D model with ECs and EPCs promoted network formation compared to CM from an EC monoculture. We also confirmed that EPCs secreted vascular endothelial growth factor (VEGF). However, networks cultured with the CM were shallow and did not penetrate the collagen gel in great depth. Therefore, we conclude that EPCs contribute to 3D network formation at least through indirect incorporation by generating a local VEGF gradient. These results suggest that the location of EPCs is important for controlling directional 3D network formation in the field of tissue engineering

Recovery of Platinum Group Metals from Spent Automotive Catalysts Using Lithium Salts and Hydrochloric Acid

The recovery of platinum group metals (PGMs) from waste materials involves dissolving the waste in an aqueous solution. However, since PGMs are precious metals, their dissolution requires strong oxidizing agents such as chlorine gas and aqua regia. In this study, we aimed to recover PGMs via the calcination of spent automotive catalysts (autocatalysts) with Li salts based on the concept of “spent autocatalyst + waste lithium-ion batteries” and leaching with only HCl. The results suggest that, when Li2CO3 was used, the Pt content was fully leached, while 94.9% and 97.5% of Rh and Pd, respectively, were leached using HCl addition. Even when LiF, which is a decomposition product of the electrolytic solution (LiPF6), was used as the Li salt model, the PGM leaching rate did not significantly change. In addition, we studied the immobilization of fluorine on cordierite (2MgO·2Al2O3·5SiO2), which is a matrix component of autocatalysts. Through the calcination of LiF in the presence of cordierite, we found that cordierite thermally decomposed, and fluorine was immobilized as MgF2

Recovering Lithium from the Cathode Active Material in Lithium-Ion Batteries via Thermal Decomposition

In this study, calcination tests were performed on a mixed sample of lithium cobalt oxide and activated carbon at 300–1000 °C under an argon atmosphere. The tests were conducted to discover an effective method for recovering lithium and cobalt from the cathode active material used in lithium-ion batteries. Additionally, the effect of soluble fluorine on the purification of lithium carbonate was investigated by the addition of lithium fluoride to an aqueous lithium hydroxide solution and a CO2 flow test was performed. The lithium recovery was ≥90% when the calcination occurred at temperatures of 500–600 °C. However, the percent recovery decreased at temperatures ≥700 °C. It was demonstrated that in order to increase the recovery while maintaining 99% purity of lithium carbonate in the recovered material, it was imperative to increase the temperature of the solution and to limit the F/Li ratio (mass%/mass%) in the solution to a value that did not exceed 0.05

Heat dissipation characteristics of magnetite nanoparticles and their application to macrophage cells

Abstract We report the results of the study undertaken to determine relative contributions of Néel and Brownian relaxations on magnetic heat dissipation by investigating the physical, magnetic and heating characteristics of magnetite suspension dispersing particles ranging in average diameter from 10.0 to 15.7 nm. Heating characteristics depended on the primary particle size and the viscosity of the medium. In the case of the sample with average diameter of 12.5 nm, the effective specific absorption rate dropped by 27 % (22.9×10 -9 to 16.8×10 -9 Wg -1 Oe -2 Hz -1 ). In contrast, the decrease of 67 % (29.5×10 -9 to 9.7×10 -9 Wg -1 Oe -2 Hz -1 ) was observed for the sample with average diameter of 15.7 nm. The potential of these particles as thermal seeds was tested by feeding the macrophage and exposing them to an alternative current magnetic field strength and frequency of 40 Oe and 600 kHz, respectively. The uptake of magnetite particles by the macrophage was adequate to raise the temperature of cell suspension by 8 o C required for thermal necrosis

Novel Mechanically Assisted Dissolution of Platinum Using Cerium(IV) Oxide

Platinum group metals (PGMs) are important for a variety of applications, including catalysis; however, the amounts mined are inadequate relative to global requirements. Therefore, methods for the recovery of PGMs from spent resources are urgently required. Herein, we report that platinum (Pt) can be dissolved by hydrochloric acid (HCl) alone using cerium(IV) oxide (CeO2) as a solid oxidizing agent, which can minimize the highly corrosive chlorine. Pt-containing catalysts were subjected to high-energy ball milling in the presence of CeO2, and their dissolution behavior in HCl was subsequently investigated. Ball milling was found to promote direct Pt-oxidation, as indicated by the significantly increased solubility in HCl. Several analytical techniques, including X-ray diffractometry, surface area and pore size analysis, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, inductively coupled plasma mass spectrometry, and atomic emission spectroscopy, were used for characterization. This study demonstrates the environmentally acceptable characteristics of high-energy ball milling and its applicability in the recycling of important noble metal substances from waste materials

3D endothelial network formation in the depth direction in EC and EC+EPC models.

<p>Representative fluorescent images of a confluent EC layer on the surface of collagen gel (<b>A</b>, <b>C</b>) and EC networks in the collagen gel (<b>B</b>, <b>D</b>) are shown. (<b>E</b>) The depth of the EC and EC+EPC models was quantitatively analyzed. The depth of 3D endothelial networks in the EC+EPC model was deeper than that in the EC model. However, the difference was not remarkable according to the concentration of bFGF. Data are presented as the means ± SD (n = 6–26; *<i>p</i> < 0.001 vs. EC model with 10 ng/mL bFGF; ^†<i>p</i> < 0.001 vs. EC model with 30 ng/mL bFGF). Scale bar, 100 μm.</p

Three-dimensional endothelial network models.

<p>(<b>A</b>) In the EC model, ECs were seeded onto collagen gel. The EC monoculture served as a control. (<b>B</b>) In the EC+EPC model, EPCs were sandwiched with double layers of collagen gel. ECs were then cultured on the top of the upper collagen gel layer. In each model, some ECs in a confluent monolayer invaded the underlying collagen gel with the addition of bFGF (Sprout) and formed 3D endothelial networks in culture (3D network).</p