We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO₂. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe³⁺-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe²⁺-oxidation, dependent on microbially produced nitrate.

The g factors of $2_1^{+},$ $4_1^{+},$ and $2_2^{+}$ states in the stable ${}^{130,132,134,136}\mathrm{Xe}$ isotopes have been measured via projectile Coulomb excitation in inverse kinematics in combination with the transient field technique. The results show a steady decrease in ${g(2\mathrm{}}_1^{+})$ as the number of neutron holes increases in the lighter nuclei below the closed $N=82\mathrm{}$ neutron shell. The g factors of the $4_1^{+}$ states in ${}^{132,134}\mathrm{Xe}$ are consistently larger than the g factors of the $2_1^{+}$ states, a characteristic of proton excitation. The g factors of the $2_1^{+},$ $4_1^{+},$ and $2_2^{+}$ states in ${}^{130}\mathrm{Xe}$ are approximately equal as would be expected for vibrational excitations.

The g factors of the $2_1^{+}$ and $4_1^{+}$ states in ${}^{78,80,82,84,86}\mathrm{Kr}$ have been measured for the first time, using Coulomb excitation of isotopic Kr beams and the transient field technique. The measured g factors of $2_1^{+}$ states in ${}^{78,80,82}\mathrm{Kr}$ are well described, in both magnitude and progression with neutron number, by the IBA-II model. Whereas the lighter isotopes show a dominant collective structure with g factor values close to $Z/A,$ the large ${g(2\mathrm{}}_1^{+})=1.12\mathrm{}(14)\mathrm{}$ value of ${}^{86}\mathrm{Kr},$ with its closed $N=50\mathrm{}$ shell, is unequivocally dominated by specific proton configurations. The g factor of the $2_1^{+}$ state in ${}^{84}\mathrm{Kr},$ with two holes in the ${1g}_{9/2}$ neutron orbit, reflects both proton and neutron components in the wave function. In addition, the lifetimes of several $2_1^{+}$ and $4_1^{+}$ states were remeasured by the Doppler shift attenuation method, yielding values which, in some cases, differ from those in the literature.

The last decade has seen a rapid growth in our understanding of the microscopic origins of shape coexistence, assisted by the new data provided by the modern radioactive ion beam facilities built worldwide. Islands of the nuclear chart in which shape coexistence can occur have been identified, and the different microscopic particle–hole excitation mechanisms leading to neutron-induced or proton-induced shape coexistence have been clarified. The relation of shape coexistence to the islands of inversion, appearing in light nuclei, to the new spin-aligned phase appearing in $N=Z$ nuclei, as well as to shape/phase transitions occurring in medium mass and heavy nuclei, has been understood. In the present review, these developments are considered within the shell-model and mean-field approaches, as well as by symmetry methods. In addition, based on systematics of data, as well as on symmetry considerations, quantitative rules are developed, predicting regions in which shape coexistence can appear, as a possible guide for further experimental efforts that can help in improving our understanding of the details of the nucleon–nucleon interaction, as well as of its modifications occurring far from stability.