Background The immune profile against SARS-CoV-2 has dramatically diversified due to a complex combination of exposure to vaccines and infection by various lineages/variants, likely generating a heterogeneity in protective immunity in a given population. To further complicate this, the Omicron variant, with numerous spike mutations, has emerged. These circumstances have created the need to assess the potential of immune evasion by the Omicron in individuals with various immune histories. Methods The neutralization susceptibility of the variants including the Omicron and their ancestor was comparably assessed using a panel of plasma/serum derived from individuals with divergent immune histories. Blood samples were collected from either mRNA vaccinees or from those who suffered from breakthrough infections by the Alpha/Delta with multiple time intervals following vaccination. Findings The Omicron was highly resistant to neutralization in fully vaccinated individuals without a history of breakthrough infections. In contrast, robust cross-neutralization against the Omicron were induced in vaccinees that experienced breakthrough infections. The time interval between vaccination and infection, rather than the variant types of infection, was significantly correlated with the magnitude and potency of Omicron-neutralizing antibodies. Conclusions Immune histories with breakthrough infections can overcome the resistance to infection by the Omicron, with the vaccination-infection interval being the key determinant of the magnitude and breadth of neutralization. The diverse exposure history in each individual warrants a tailored and cautious approach to understanding population immunity against the Omicron and future variants. Funding This study was supported by grants from the Japan Agency for Medical Research and Development (AMED).

The electronic structures of the ternary thallium chalcogenide compounds, TlGaSe 2 and TlGaS 2 are studied, using the linear muffin-tin orbital (LMTO) method. The calculated band dispersion shows that both compounds are indirect gap semiconductors. For both compounds, the top of the valence bands is located at Γ. For TlGaSe 2 , the bottom of the conduction band is located along the Z(0, 0, -5)-L(0.5, 0.5, -0.5) line. For TlGaS 2 , the bottom of the conduction band is located along the Γ -Y(0, 1, 0) line. An inspection of the LMTO wave functions shows that the valence band top has the character of Tl : 6s -Se : 4p or S : 3p antibonding state, while the conduction band bottom has the character of Tl : 6p -Se : 4p or S : 3p antibonding state.

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Unveiling dissolved species in electrodeposition baths helps our understanding of electrodeposition behavior, such as growth orientation. A highly concentrated aqueous alkaline copper(II)-lactate solution is used for the electrodeposition of copper(I) oxide (Cu 2 O) thin films with <111> orientations; the semiconductor properties of these films facilitate their use in solar-cell materials, photocathodes, and photocatalysts. However, the dissolved species, presumably copper(II)-lactate complexes, cannot be deduced on the basis of known thermodynamic data, and have not been convincingly determined yet. In this work, we determine these cupric complexes by pH titration, ultraviolet-visible spectroscopy, and electrospray-ionization mass spectrometry (ESI-MS), including probe-ESI-MS (PESI-MS). Using PESI-MS, we successfully analyzed a highly concentrated solution without sample dilution. The determined complexes are Cu(H -1 L)L -and Cu(H -1 L) 2 2-, where the H -1 L 2-(CH 3 CH(O -)COO -) is a lactate ion with a deprotonated α-hydroxyl group. As far as we know, this is the first direct experimental observation of H -1 L 2-ions in a highly concentrated aqueous alkaline copper(II)-lactate solution. We also propose that H -1 L 2-is stabilized by the high concentration and through coordination to copper(II) ions. Cuprous oxide (Cu 2 O) is a p-type semiconductor that is inexpensive and of low toxicity. Cu 2 O thin films are attracting increasing attention as solar-cell materials, 1-5 photocathodes, 6-9 and photocatalysts 10-12 for, for example, water splitting. Among thin-film fabrication methods, electrodeposition from an aqueous solution has advantages over conventional methods, such as chemical vapor deposition, because of its low cost and low environmental burden. Moreover, it is easy to obtain cubic Cu 2 O with the preferential <111> orientation by tuning the pH of the electrodeposition bath;13-17 this orientation relaxes lattice misfit with hexagonal ZnO, which is favorable for Cu 2 O-ZnO solar cells.Since the pioneering work of Rakhshani et al., 13 highly concentrated aqueous alkaline solutions have commonly been used for Cu 2 O electrodeposition;13-16 these solutions contain 0.4 M of a copper(II) salt and 3.0 M lactic acid (HL; CH 3 CH(OH)COOH) as the complexing agent, and the pH is adjusted to be in the 9.0-12.5 range. [13][14][15][16] The crystal orientation of the electrodeposited Cu 2 O is pH dependent; i.e. it is <100> at pH values of 9.0 and 9.5, and <111> at pH values of 12.0 and 12.5. [13][14][15][16][17] The pH dependence of the crystal orientation during Cu 2 O electrodeposition may be ascribable to changes in the dissolved copper(II)-lactate complexes. 6,15,16 Unfortunately, to the best of our knowledge, there are no available thermodynamic data for these copper(II)-lactate complexes under these alkaline conditions, especially for such concentrated solutions. Two previous reports have indicated the presence of dissolved copper(II)-lactate complexes in such concentrated alkaline solutions; Leopold et al. a...