In the latest paper uploaded, Holmlid suggests that there are results related to ultra-dense hydrogen in the scientific literature, which might partially answer the above question:
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Related results on ultra-dense hydrogen exist in the literature. A superconductive state consisting of very high-density hydrogen clusters in voids (Schottky defects) in palladium crystals has been studied experimentally by Lipson et al. [17]. This effect was discussed as due to Bose-Einstein condensation [18] or a Casimir effect [19]. Such hydrogen clusters may give increased nuclear fusion gains [20]. The close relation between these hydrogen clusters and ultra-dense hydrogen has been pointed out [21].
References 17-21:
[17]. A. Lipson, B. J. Heuser, C. Castano, G. Miley, B. Lyakhov, and A. Mitin, Transport and magnetic anomalies below 70 K in a hydrogen-cycled Pd foil with a thermally grown oxide, Phys. Rev. B 72, 212507 (2005). DOI: 10.1103/PhysRevB.72.212507
[18] G. H. Miley, H. Hora, K. Philberth, A. Lipson, and P. L. Shrestha, in Low-Energy Nuclear Reactions and New Energy Technologies Source Book, eds. J. Marwan and S. B. Krivit, Vol. 2, p. 235-252 (American Chemical Society/Oxford University Press, Washington DC, 2009).
[19] H. Hora, G. H. Miley, Maruhn–Greiner maximum of uranium fission for confirmation of low energy nuclear reactions LENR via a compound nucleus with double magic numbers. J. Fusion Energ. 26, 349 (2007).
[20] X. Yang, G. H. Miley, K. A. Flippo, and H. Hora, Energy enhancement for deuteron beam fast ignition of a precompressed inertial confinement fusion target, Phys. Plasmas 18, 032703 (2011).
[21] L. Holmlid, H. Hora, G. Miley, and X. Yang, “Ultrahigh-density deuterium of Rydberg matter clusters for inertial confinement fusion targets”. Laser Part. Beams 27, 529 (2009). https://doi.org/10.1017/S0263034609990267