Crystals最新文献

GpsB is a conserved cell-cycle regulator in the Firmicute clade of Gram-positive bacteria that coordinates multiple aspects of envelope biogenesis. Recent studies demonstrate interactions between GpsB and the key division cytoskeleton FtsZ, suggesting that GpsB links cell division to various aspects of cell envelope biogenesis in Staphylococcus aureus and potentially other Firmicutes. We determined a 1.7 Å resolution crystal structure of the N-terminal domain of Staphylococcus aureus GpsB, revealing an asymmetric dimer with a bent conformation. This conformation is nearly identical to one of two conformations reported by Sacco, et al., confirming the unique conformation of S. aureus GpsB compared to other gram-positive bacteria. This structural agreement provides strong validation of the S. aureus GpsB fold and supports its proposed role in organizing the cell division machinery.

The vibration properties of materials play a role in their conduction of electric charges. are Ionic conductors such as electrodes and solid electrolytes are also relevant in this respect. The vibration properties are typically assessed with infrared and Raman spectroscopy, and inelastic neutron scattering, which all allow for the derivation of the phonon density of states (PDOS) in part of a full portion of the Brioullin zone. Nuclear resonant vibration spectroscopy (NRVS) is a novel method that produces the element-specific PDOS from Mössbauer-active isotopes in a compound. We employed NRVS operando on a pouch cell battery containing a Li⁵⁷FePO₄ electrode, and thus could derive the PDOS of the ⁵⁷Fe in the electrode during charging and discharging. The spectra reveal reversible vibrational changes associated with the two-phase conversion between LiFePO₄ and FePO₄, as well as signatures of metastable intermediate states. We demonstrate how the NRVS data can be used to tune the atomistic simulations to accurately reconstruct the full vibration structures of the battery materials in operando conditions. Unlike optical techniques, NRVS provides bulk-sensitive, element-specific access to the full phonon spectrum under realistic operando conditions. These results establish NRVS as a powerful method to probe lattice dynamics in working batteries and to advance the understanding of ion transport and phase transformation mechanisms in electrode materials.

The development of advanced biomaterials for dental applications has gained significant attention due to the need for enhanced mechanical properties, biocompatibility, and antibacterial activity. Hydroxyapatite (HA) is widely used in bone tissue engineering owing to its chemical similarities to bone. However, biofilm formation and bacterial infection on HA may lead to implant failure and revision surgery. Tannic acid, a polyphenolic compound with strong antibacterial and antioxidant properties, was incorporated into the composite to provide antimicrobial effects, that may address the challenge of biofilm formation on dental surfaces. In this study, the biomedical potential of tannic acid (TA)-loaded hydroxyapatite-zirconia composites were analyzed. The crystallization characteristics, functional groups, and morphology were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM) analysis. The biocompatibility of composite samples was analyzed through in vitro cell culture studies. The combined effect of TA and zirconia showed antibacterial efficacy against Staphylococcus aureus (S. aureus) after 24 h of sample-bacterial interactions. The results demonstrate that this tannic acid-loaded hydroxyapatite-zirconia composite holds significant promise for improving the performance of dental materials and preventing infections in oral healthcare applications.