Age, Disease Severity and Ethnicity Influence Humoral Responses in a Multi-Ethnic COVID-19 Cohort

The COVID-19 pandemic has affected all individuals across the globe in some way. Despite large numbers of reported seroprevalence studies, there remains a limited understanding of how the magnitude and epitope utilization of the humoral immune response to SARS-CoV-2 viral anti-gens varies within populations following natural infection. Here, we designed a quantitative, multi-epitope protein microarray comprising various nucleocapsid protein structural motifs, including two structural domains and three intrinsically disordered regions. Quantitative data from the microarray provided complete differentiation between cases and pre-pandemic controls (100% sensitivity and specificity) in a case-control cohort (n = 100). We then assessed the influence of disease severity, age, and ethnicity on the strength and breadth of the humoral response in a multi-ethnic cohort (n = 138). As expected, patients with severe disease showed significantly higher antibody titers and interestingly also had significantly broader epitope coverage. A significant increase in antibody titer and epitope coverage was observed with increasing age, in both mild and severe disease, which is promising for vaccine efficacy in older individuals. Additionally, we observed significant differences in the breadth and strength of the humoral immune response in relation to ethnicity, which may reflect differences in genetic and lifestyle factors. Furthermore, our data enabled localization of the immuno-dominant epitope to the C-terminal structural domain of the viral nucleocapsid protein in two independent cohorts. Overall, we have designed, validated, and tested an advanced serological assay that enables accurate quantitation of the humoral response post natural infection and that has revealed unexpected differences in the magnitude and epitope utilization within a population

Structural, electrical conductivity and dielectric relaxation behavior of LiHf2(PO4)3 ceramic powders

Lithium hafnium phosphate LiHf2(PO4)3 (LHP) was synthesized via solid-state synthesis technique. The sintering behavior, structure, and phase composition of the as-prepared sample was analyzed using X-ray diffraction (XRD) characterization technique. The XRD-Rietveld refinement analysis showed that after sintering at low temperatures 500 to 1000 °C, it exhibited various secondary phases. However, a single phase was observed as the sintering temperature increases from 1100 to 1200 °C. LHP sintered at 1100 °C produced real features of sodium superionic conductor type (NASICON-type) with hexagonal crystal axis indicating R-3c space group. The electrical properties were studied using impedance spectroscopy technique. Frequency and temperature dependence behavior of conductivity (ac and dc) and dielectric permittivity were studied. The results obtained describes the conduction mechanism in the system. Electric modulus formalism was performed to investigate the relaxation behavior which showed that as measuring temperature increases, the relaxation frequency increases whereas relaxation time decreases. This behavior explains the hopping mechanism of the charge carriers in the system. Likewise, the correlated barrier hopping model elucidates the dominant hopping mechanism

Erratum to: Thermal–mechanical behaviour of chitosan–cellulose derivative thermoreversible hydrogel films

CH, Chitosan; HPMC, (Hydroxypropyl)methyl cellulose; FT, Freeze-thaw; SC, Solvent casting; CH:HPMC (X:Y), pH Z, FT/SC, Chitosan and (hydroxypropyl)methyl cellulose hydrogel, at X and Y proportion (0-100), at Z pH (3.0-4.0) and prepared by freeze-thaw or solvent casting techniques; DSC, Differential scanning calorimetry; MDSC, Temperature modulated Differential scanning calorimetry; Tg, glass transition temperature; ΔH, enthalpy change; TGA, Thermogravimetric Analysis; TG, Thermogravimetry; DTG, Derivative or Differential thermogravimetry; σ, Tensile strength; ε, elongation at break; DMA, Dynamic mechanical analysis; X-Ray, X-radiation, FTIR-ATR, Attenuated total reflectance Fourier transform infrared spectroscopy; SEM, Scanning electron microscopy.The authors are thankful to the Chemistry and Physic Centres at Minho University (Pest-C/QUI/UI0686/2013 and PEST-C/FIS/UI607/2013), CNPq, FAPESP and CAPES for the financial support of this research. Sandra Cerqueira Barros and Carlos M. Costa acknowledge the Portuguese Foundation for Science and Technology for the Post-Doc and PhD grants provided (SFRH/BPD/85399/2012 and SFRH/BD/68499/2010) and M. M. Silva acknowledges to CNPq, for the mobility grant provided by this institution. The authors of this paper are grateful to the Company Devan-Micropolis, S.A., for the material support, namely the natural polymers chitosan (CH) and (hydroxypropyl)methyl cellulose (HPMC) employed in this study. JLGR acknowledges the support of Ministerio de Economía y Competitividad, MINECO, through the MAT2013-46467-C4-1-R project. CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund