{We use resonant photoemission spectroscopy (resPES) to study the electronic properties of amorphous ZnO (a-ZnO) layers. We report on the core levels, the valence band (VB) PES data, and the X-ray absorption (XAS) data which we use for the conduction band (CB) density of states. From these results we are able to derive the partial density of states (pDOS) of O2p and Zn4s4p states in the VB and CB, respectively as well as a band scheme. At the O1s resonance we observe a band of localized defect states which is located between the Fermi energy and the CBM. At the Zn2p edge the XAS data indicate that localized Zn4s4p states are involved in the DOS starting already at the Fermi energy. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}

Abstract One of the unresolved aspects of cellulose-based liquid crystalline phases is their chirality. Although cellulose is intrinsically chiral, both left-handed (LH) and right-handed (RH) chiral nematic phases are reported in cellulose derivatives under different conditions. The origin of these discrepancies?and whether LH and RH twisted structures coexist within a single material?has remained unclear. Here, the first direct evidence of hierarchical LH and RH twisted structures coexisting in a solvent-free, thermotropic cellulose derivative at room temperature is provided. Free-standing cholesteric films exhibit distinct LH and RH twisted domains, whose pitches respond oppositely to uniaxial mechanical strain: the LH pitch increases, while the RH pitch decreases with increasing strain. This contrasting response results from the coexistence of intertwined LH and RH twisted structures, whose optical axes are oriented differently relative to the strain direction. Notably, after stretching beyond their elastic limit, the films spontaneously recover their original shape within minutes. During this recovery, circular dichroism (CD) measurements reveal an increase in RH pitch and a decrease in LH pitch, evidencing reversible, strain-responsive behavior. Multiscale structural characterization confirms the hierarchical chiral organization and its mechanoresponsive nature, providing new insights into the origin of chirality in cellulose-based liquid crystalline materials.

Uracil-DNA glycosylases (UDGs) are widely used to prevent carryover contamination in nucleic acid amplification–based diagnostics; however, existing thermolabile UDGs exhibit limited thermal inactivation windows for emerging applications. Here, we combine evolutionary mining, structural analysis, and structure-guided saturation mutagenesis to define non-catalytic determinants that tune UDG thermolability without compromising catalytic function. From 8482 bacterial UDG sequences, we assembled a 24-member diversity panel and identified UDG_7 as a naturally thermolabile scaffold coupling robust low-temperature activity with sharp inactivation near 45 °C. The crystal structure of UDG_7 reveals a canonical family-I α/β fold with a fully conserved active site, closely resembling both mesophilic human and Escherichia coli UDGs and thermolabile cod UDG. These structural insights guided the design of a single-site variant library targeting 48 non-catalytic positions involved in packing and electrostatic networks. Pooled thermal shift assays distinguished a rigid structural core from 16 surface thermolability hotspots. A high-throughput functional screening of 480 single mutants yielded 114 clones with a desirable “on–off–off” profile and, after sequence consolidation, identified 54 unique variants that retained activity at 25 °C but lost activity at 30 to 37.5 °C. Biochemical characterization revealed nine single substitutions, Q51I, T112Y, V144M, D167F, R201F, R201Y, D219M, R221P, and R221D, that markedly lower the melting temperature while preserving near-native activity. Together, these results indicate that UDG_7 thermolability is encoded by a distributed, surface-biased electrostatic network that can be selectively disrupted without perturbing the conserved catalytic core, shifting the functional inactivation boundary downward and supporting robust carryover control under low-temperature amplification constraints.