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Pristine HfO 2 tends to have a monoclinic phase with a low dielectric constant. Reportedly, yttrium(Y) doping has been used to induce the tetragonal phase in HfO 2 , with Y contributing to the formation of the tetragonal phase and improving the crystallinity. However, Y doping in HfO 2 forms oxygen vacancies, resulting in a relatively high leakage current. Owing to the difficulty in suppressing the oxygen vacancies crucial for inducing the tetragonal phase, we focused on another significant leakage current path: the grain boundary. Introducing a heterostructure is expected to reduce the grain size and mitigate the leakage current by increasing the length of the leakage path. This study compares the dielectric constant and leakage current based on the stacking sequence of ZrO 2 and Y-doped HfO 2 (Y-HfO 2) and elucidate the underlying differences through electrical analysis. Additionally, crystallographic analysis reveals the reasons for the structural order-dependent variations in the electrical properties. Finally, the structure with a Y-HfO 2 layer at the bottom demonstrates advantages in achieving a lower leakage current. [ABSTRACT FROM AUTHOR]

Bacteroides fragilis resides in mammals and human intestines and secrete series of proteins and molecules outside that cause various diseases such as colon cancer and chronic colitis in the host. B. fragilis has been shown to produce numerous proteins to the infected cell surface which are involved in host colonization, microbial interactions, and pathogenicity. Among secreted proteins, a B. fragilis toxin (BFT) is a metalloprotease and disintegrates the epithelial cell layer and causes colon cancers. Except the BFT, information of secreted proteases from B. fragilis is limited and no structure is available. Aspartic proteinase cleaves a peptide bond using two aspartate residues in a catalytic site in acidic conditions, pH ranges from 3 to 6. Aspartic proteinase have been characterized mostly from eukaryotes and retroviruses but rare from bacteria including B. fragilis. A putative aspartic proteinase is identified from the B. fragilis genome and prepared recombinantly as a Bacteroides aspartic proteinase (BAPtase). The crystal structure of BAPtase was determined at 2.6 Å. Structure-based comparative and endopeptidase analyses demonstrated that BAPtase presents a two-domain structure and is a functional aspartic proteinase in unusually weak basic pHs, which would propose to be a critical in bacterial pathogenesis and in host immunity. Our observations on the distinct structural and catalytic properties of BAPtase would benefit the future development of B. fragilis -specific drugs or preventatives. • The crystal structure of aspartic proteinase from B. fragilis (BAPtase) was determined and analyzed. • BAPtase contains tandem β-barrels like other aspartic proteases but has a unique N-terminal α-helical domain. • BAPtase exerts aspartic proteinase activity unusually at weakly alkaline conditions. [ABSTRACT FROM AUTHOR]

Upon encountering allergens, CD4+ T cells differentiate into IL-4-producing Th2 cells in lymph nodes, which later transform into polyfunctional Th2 cells producing IL-5 and IL-13 in inflamed tissues. However, the precise mechanism underlying their polyfunctionality remains elusive. In this study, we elucidate the pivotal role of NRF2 in polyfunctional Th2 cells in murine models of allergic asthma and in human Th2 cells. We found that an increase in reactive oxygen species (ROS) in immune cells infiltrating the lungs is necessary for the development of eosinophilic asthma and polyfunctional Th2 cells in vivo. Deletion of the ROS sensor NRF2 specifically in T cells, but not in dendritic cells, significantly abolished eosinophilia and polyfunctional Th2 cells in the airway. Mechanistically, NRF2 intrinsic to T cells is essential for inducing optimal oxidative phosphorylation and glycolysis capacity, thereby driving Th2 cell polyfunctionality independently of IL-33, partially by inducing PPARγ. Treatment with an NRF2 inhibitor leads to a substantial decrease in polyfunctional Th2 cells and subsequent eosinophilia in mice and a reduction in the production of Th2 cytokines from peripheral blood mononuclear cells in asthmatic patients. These findings highlight the critical role of Nrf2 as a spatial and temporal metabolic hub that is essential for polyfunctional Th2 cells, suggesting potential therapeutic implications for allergic diseases. [ABSTRACT FROM AUTHOR]

Herein, the deposition of homogeneous ZrxHf(1−x)O2 (x < 1) thin films for dynamic random‐access memory (DRAM) capacitor dielectric layers by atomic layer deposition (ALD) using a mixed precursor mixture of two precursors is investigated. ZrO2‐ and HfO2‐based thin films are widely used as capacitor dielectric layers because of their high dielectric constant (k) values and low leakage current properties. Herein, particularly, films with mixed structures of ZrO2/HfO2 are investigated because ZrO2 supports the growth of HfO2 in the tetragonal phase. However, the mixed structures deposited by ALD remain inhomogeneous even after the annealing process. The inhomogeneity results in part of the HfO2 remaining in the monoclinic phase, which reduces the k value. Herein, the formation of homogeneous tetragonal‐phase ZrxHf1−xO2 using a mixed precursor consisting of CpZr and CpHf precursors is investigated. The formation of the tetragonal phase in the ZrxHf(1−x)O2 thin films is determined through chemical and structural analysis. The variation of the electrical properties with the Zr/Hf concentration ratio is investigated. The electrical properties are enhanced compared to laminated ZrO2/HfO2 and single thin films. [ABSTRACT FROM AUTHOR]

A Y-doped HfO 2 thin film deposited using a cocktail precursor for a DRAM capacitor dielectric application was investigated. It has been difficult to adapt HfO 2 , a potential high-dielectric-constant material, deposited by a typical thin-film deposition technique to actual devices owing to its low dielectric constant of approximately 20, resulting from its monoclinic-phase crystal structure. Although several methods have been investigated to increase the dielectric constant by crystal structure transformation to the tetragonal phase, which has a dielectric constant as high as approximately 40, the formation of the monoclinic phase was not successfully suppressed. In this study, the tetragonal-phase formation of HfO 2 thin films was investigated using a cocktail precursor consisting of Y and Hf precursors. The monoclinic formation suppression mechanism in the Y-doped HfO 2 thin film was determined from the physical and chemical analyses results. Moreover, the leakage current change caused by the introduced oxygen vacancy with respect to the Y dopant concentration was investigated. Improved electrical properties of the dielectric constant and leakage current were achieved with Y-doped HfO 2. [ABSTRACT FROM AUTHOR]

Since the first discovery of phenolic acid decarboxylase transcriptional regulator (PadR), its homologs have been identified mostly in bacterial species and constitute the PadR family. PadR family members commonly contain a winged helix-turn-helix (wHTH) motif and function as a transcription factor. However, the PadR family members are varied in terms of molecular size and structure. As a result, they are divided into PadR subfamily-1 and PadR subfamily-2. PadR subfamily-2 proteins have been reported in some pathogenic bacteria, including Listeria monocytogenes and Streptococcus pneumoniae , and implicated in drug resistance processes. Despite the growing numbers of known PadR family proteins and their critical functions in bacteria survival, biochemical and biophysical studies of the PadR subfamily-2 are limited. Here, we report the crystal structure of a PadR subfamily-2 member from Streptococcus pneumoniae (SpPadR) at a 2.40 Å resolution. SpPadR forms a dimer using its N-terminal and C-terminal helices. The two wHTH motifs of a SpPadR dimer expose their positively charged residues presumably to interact with DNA. Our structure-based mutational and biochemical study indicates that SpPadR specifically recognizes a palindromic nucleotide sequence upstream of its encoding region as a transcriptional regulator. Furthermore, comparative structural analysis of diverse PadR family members combined with a modeling study highlights the structural and regulatory features of SpPadR that are canonical to the PadR family or specific to the PadR subfamily-2. • The structure of the putative transcriptional factor PadR from S. pneumoniae was characterized. • SpPadR recognizes an operator sequence in its own gene. • The SpPadR structure suggests the canonical features of the PadR subfamily −2. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is a widely found opportunistic pathogen. The emergence of multidrug-resistant strains and persistent chronic infections have increased. The protein encoded by the pa0423 gene in P. aeruginosa is proposed to be critical for pathogenesis and could be a virulence-promoting protease or a bacterial lipocalin that binds a lipid-like antibiotic for drug resistance. Although two functions of proteolysis and antibiotic resistance are mutually related to bacterial survival in the host, it is very unusual for a single-domain protein to target unrelated ligand molecules such as protein substrates and lipid-like antibiotics. To clearly address the biological role of the PA0423 protein, we performed structural and biochemical studies. We found that PA0423 adopts a single-domain β-barrel structure and belongs to the lipocalin family. The PA0423 structure houses an internal tubular cavity, which accommodates a ubiquinone-8 molecule. Furthermore, we reveal that PA0423 can directly interact with the polymyxin B antibiotic using the internal cavity, suggesting that PA0423 has a physiological function in the antibiotic resistance of P. aeruginosa. • The crystal structure of the Pseudomonas aeruginosa PA0423 protein was determined. • PA0423 folds into a β-barrel structure that features an internal cavity. • PA0423 accommodates the ubiquinone-8 ligand into the cavity of the structure. • PA0423 binds polymyxin B, suggesting an antibiotic-sequestering function. [ABSTRACT FROM AUTHOR]

[Display omitted] • The phase transformation mechanism of HfO 2 from monoclinic to tetragonal by employing the intrinsic and extrinsic effects was revealed. • The surface energy difference between the tetragonal and monoclinic phases induces the phase transformation depending on the layer thickness of HfO 2. • The tetragonal phase crystallization below the critical thickness of HfO 2 was induced by the template effect of ZrO 2 , which had tetragonal phase as well, in the ZrO 2 /HfO 2 nano-laminated structure. • Based on the measurement of dielectric constant values depending on the phase compositions of the HfO 2 layer in the ZrO 2 /HfO 2 nano-laminated structure deposited by the atomic layer deposition process, the dielectric constant of each phase was calculated. Phase transition of HfO 2 thin film has been investigated to demonstrate desirable electrical properties, such as high dielectric constant or ferroelectricity, however, the most of results exhibited a limitation on enhancing the crystallinity because of employing dopant. In this study, the crystallization behavior in the thin film was investigated in the intrinsic and extrinsic aspects. In the laminated structure, highly crystallized tetragonal phased HfO 2 was obtained by controlling the layer thickness and adapting the template effect for intrinsic and extrinsic crystallization, respectively, without using dopant. Moreover, by the phase composition analysis, the dielectric constant of various crystal structures of HfO 2 thin film, tetragonal, monoclinic, and amorphous phases, were revealed using the data obtained from the real deposited thin film by atomic layer deposition process, not from the theoretical calculation. [ABSTRACT FROM AUTHOR]