This Special Issue of Energies has emerged as a result of the 1st International Conference on Nanofluids (https://icnf2019.com/), which was organized under the auspices of Nanouptake COST Action (Overcoming Barriers to Nanofluids Market Uptake, http://www.nanouptake.eu/) in Castelló (Spain), in June 2019. The foci of ICNf2019 were the production and the characterisation of nanofluids for different areas of applications in the energy fields, namely heat transfer, storage of thermal energy, boiling, and solar systems, as well as industrial applications and health and safety issues. The first conference edition on this topic gathered more than 200 participants from 45 different countries. More than 125 contributions were presented in the nine sections of the congress. Some selected authors were invited to send extended versions of their work to the Energies ICNf2019 Special Issue. After a careful review process, nine articles from six different countries were selected for compilation in this Special Issue: a total of seven full research papers and two reviews. These papers cover a broad range of fundamental and applied research aspects on nanofluid science and development, and reflect the current investigations, knowledge, and challenges encountered in the use of nanofluids for energy applications.

These volumes contain 365 of the 505 papers presented at the VUV-11 Conference, held at Rikkyo University, Tokyo, from August 27th to September 1st 1995. The papers are divided into three sections: atomic and molecular spectroscopy, solid state spectroscopy and instrumentation and technological applications. New aspects presented were both quantitative and qualitative improvements in fluorescence spectroscopy and magnetic circular dichroism measurements. The fluorescence data are complementary to those of photoemission in a sense but they appear to open up a new method to analyze the optical excitation and relaxation processes. The application of magnetic circular dichroism has proved to be useful not only in analyzing the electronic structures of magnetic materials but also in practical applications to material engineering as found in experiments combined with photoelectron microscopy. Excellent developments in applications are only found in the field of surface photochemistry, where the technique of etching using VUV light has been appreciably refined. Although the majority of distinctive scientific features in the VUV-11 Conference have been brought about by the application of synchrotron radiation, experiments using a different type of light source appear to have progressed steadily. This is evident in the studies of plasma radiation.