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Biogenic selenium nanoparticles (SeNPs) are the most favorable Se form for nutritional supplementation due to their high stability, low toxicity, and high activity. However, the interaction between the surface-binding proteins and their stable biogenic SeNPs, as well as their impact on the stability and bioavailability of SeNPs, remains to be understood. In vitro stabilization experiments revealed an amino acid segment (F(235–386)) in Rahnella aquatilis’ flagellin FliC, with surfactant-like properties, stabilizing SeNPs under harsh conditions. FliC and F(235–386) were employed as stabilizers to synthesize SeNPs (FliC@SeNPs and F(235–386)@SeNPs), and surface chemistry analysis revealed coordination reactions between the proteins and Se atoms on the surface of SeNPs. Both FliC and F(235–386) enhanced SeNPs uptake in wheat seedlings but reduced it in bacteria and yeast. This study highlights FliC’s core function in stabilizing SeNPs and enhancing their bioavailability, paving the way for agricultural and nutritional applications.

Purpose: Dental health has been getting increased attention. Timely detection of non-normal teeth (caries, residual root, retainer, teeth filling, etc.) is of great importance for people’s health, well-being, and quality of life. This work proposes a rapid detection of non-normal teeth based on improved Mask R-CNN, aiming to achieve comprehensive screening of non-normal teeth on dental X-ray images. Methods: An improved Mask R-CNN based on attention mechanism was used to develop a non-normal teeth detection method trained on a high-quality annotated dataset, which can segment the whole mask of each non-normal tooth on the dental X-ray image immediately. Results: The average precision (AP) of the proposed non-normal teeth detection was 0.795 with an intersection-over-union of 0.5 and max detections (maxDets) of 32, which was higher than that of the typical Mask R-CNN method (AP = 0.750). In addition, validation experiments showed that the evaluation metrics (AP, recall, precision-recall (P-R) curve) of the proposed method were superior to those of the Mask R-CNN method. Furthermore, the experimental results indicated that proposed method exhibited a high sensitivity (95.65%) in detecting secondary caries. The proposed method took about 0.12 s to segment non-normal teeth on one dental X-ray image using the laptop (8G memory, NVIDIA RTX 3060 graphics processing unit), which was much faster than conventional manual methods. Conclusion: The proposed method enhances the accuracy and efficiency of abnormal tooth diagnosis for practitioners, while also facilitating early detection and treatment of dental caries to substantially lower patient costs. Additionally, it can enable rapid and objective evaluation of student performance in dental examinations.

PhoP/PhoQ, the two-component regulatory system, plays a significant role in regulating the functions of many Gram-negative bacteria. This study investigated the function of PhoQ in Rahnella aquatilisHX2. The study generated a mutant HX2ΔphoQ with an in-frame deletion within the phoQgene in R. aquatilisHX2. The effect of phoQgene on HX2 selenium (Se) metabolism was investigated by the pure culture method, and the expression of Se metabolism–related genes was detected by real-time quantitative PCR (RT-qPCR). Wild-type HX2 and mutant HX2ΔphoQ were used to treat soil to explore the effects of soil Se cycling, plant growth, and Se uptake. Compared to the wild type, the phoQmutation lowered Se absorption and selenium nanoparticles (SeNPs) production but increased Se-methyl-selenocysteine (MeSeCys) content in the bacterial pellets. PhoQ significantly influenced the expression of pitA, cysA, hfq, and rsmJgenes involved in Se transport, metabolism, and methylation. In soils supplemented with selenite [Se(IV)], compared with the control, the bioavailability of Se was improved by HX2. The Se levels in plant shoots also significantly increased with HX2 treatment compared with the control. In addition, the residual Se (RES-Se) content increased substantially in soil treated with HX2ΔphoQ compared with HX2-treated soil, while the root biomass and plant Se content decreased. Rahnella aquatilisHX2 alters Se bioavailability in soil and ultimately changes the uptake of Se by plants. The findings of this study indicate that the phoQgene plays a vital role in Se metabolism in bacteria and Se conversion in soil.

Microbial transformation of selenite [Se(IV)] to elemental selenium nanoparticles (SeNPs) is known to be an important process for removing toxic soluble selenium (Se) oxyanions and recovery of Se from the environment as valuable nanoparticles. However, the mechanism of selenite uptake by microorganisms, the first step through which Se exerts its cellular function, remains not well studied. In this study, the effects of selenite concentration, time, pH, metabolic inhibitors, and anionic analogues on selenite uptake in Rahnella aquatilisHX2 were investigated. Selenite uptake by R. aquatilisHX2 was concentration- and time-dependent, and its transport activity was significantly dependent on pH. In addition, selenite uptake in R. aquatilisHX2 was significantly inhibited by the aquaporin inhibitor AgNO3and sulfite (SO32–), and partially inhibited by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and 2,4-dinitrophenol (2,4-DNP) treatments. Three mutants with in-frame deletions of aqpZ, glpF, and nhaA genes were constructed. The transport assay showed that the water channel protein AqpZ, and not GlpF, was a key channel of selenite uptake by R. aquatilisHX2, and sulfite and selenite had a common uptake pathway. In addition, the Na+/H+antiporter NhaA is also involved in selenite uptake in R. aquatilisHX2.

Positron emission tomography (PET) scanners with new features, such as open structure, compact size, and adaptive field of view (FOV), have attracted significant attention. Among these novel designs, panel PET has the potential to combine the open structure and variable FOV into a compact form. In this paper, we would like to further exploit these structural advantages by proposing a modified version, called the panel PET with window (PPW). A PPW is a panel PET with a rectangular opening in the center of one detector panel, which inherts the advantages of the compact size and adjustable FOV of the panel PET. Meanwhile, it utilizes fewer detector modules and offers additional flexibility and convenience in practical applications. We quantitatively evaluated the imaging performance of the PPW based on Monte Carlo simulations and real data experiments using a prototype system. The results show that the PPW system sensitivity, spatial resolution, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) deteriorate, and the effective FOV narrows down. However, the deterioration is not linear to the increase of window size. In our extreme case with 69.4% of detectors removed from a panel, the degradation of SNR, CNR, and spatial resolution are 42.4%, 43.1%, and 25.0%, respectively. Meanwhile, the contrast recovery coefficient of PPW remains almost constant.