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Polyimides with ester groups (PEsIs) are ideal dielectric materials for high-frequency communications due to their low dielectric loss (Df) and low thermal expansion coefficient (CTE). However, the rigidity of the ester segments leads to poor mechanical properties and processability of PEsIs films. To improve the toughness of this kind of polyimide, we proposed a strategy named ether-bond flexible equilibrium, that is, to prepare poly(ether-ester imide) (PEtEsI) by introducing flexible ether bonds into PEsIs, and improve their comprehensive properties by adjusting the ratio of ester groups to ether bonds. The polyimide retained the characteristics of low dielectric loss (Df < 2 × 10−3), low moisture absorption (WA < 0.7%), high thermal stability (Tg > 420 °C) and low coefficient of thermal expansion (CTE < 20 ppm K−1), similar to PEsIs, while exhibiting high mechanical strength (σ = 216 MPa), and high elongation at break (ε = 18%) when the ether content in diamine was 25%. Additionally, when the ester dianhydride monomer with naphthalene structures was used, superior performance was further exhibited due to the rigidity of naphthalene rings and the "side-step" effect. This new strategy can also be extended to other polymers for high-performance dielectric materials. [ABSTRACT FROM AUTHOR]

Background and objective: The incidence of central precocious puberty (CPP) in girls increased significantly during the COVID-19 pandemic. This study aimed to explore the impact of perfluorinated endocrine disruptors on CPP through metabolomics analysis in girls from Hainan Province, China. Methods: Serum samples from 100 girls with CPP and 100 healthy controls were collected. Untargeted metabolomics profiling was performed using ultra-high performance liquid chromatography coupled with quadrupole-Exactive Orbitrap mass spectrometry (UHPLC-Q-Exactive-Orbitrap-MS). Differentially expressed metabolites (DEMs) were screened, and pathway enrichment analysis was conducted. Results: Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) revealed distinct metabolic profiles between the CPP and control groups. A total of 511 metabolites were identified, including 296 up-regulated DEMs and 255 down-regulated DEMs. Three perfluorinated compounds—PFSM-perfluoroalkyl_sulfonamide_Me, PFSM-FSAA, and PFCA-unsaturated—were significantly upregulated in the CPP group. KEGG pathway enrichment analysis suggested the involvement of multiple pathways in the CPP process regulated by these compounds. Conclusions: Perfluorinated compounds may promote CPP in girls by interfering with various pathways and affecting the hypothalamic-pituitary-gonadal axis function. This study highlighted the need for further research and public health measures to address environmental endocrine disruptors. [ABSTRACT FROM AUTHOR]

Background: This research aimed to identify risk factors contributing to premature maturation of arteriovenous fistulas (AVF) in elderly diabetic patients and develop a clinical prediction model. Methods: We conducted a retrospective review of 548 geriatric diabetic patients who underwent AVF creation for maintenance hemodialysis (MHD) at Baoding No 1 Central Hospital between January 2011 and December 2023. Patients were divided into mature (386) and immature (162) groups based on AVF maturation status. Univariate logistic regression analysis and the least absolute shrinkage and selection operator were used to identify independent risk factors, including D-dimer levels, low-density lipoprotein cholesterol levels, internal radial meridian, radial artery plaque presence, and cephalic vein indwelling needle use history. A predictive nomogram was developed specifically for immature AVF in elderly diabetic patients. Model performance was evaluated using the area under the receiver operating characteristic curve (AUROC), calibration curve, decision curve analysis (DCA), and clinical impact curve (CIC). Results: Among elderly patients with diabetes mellitus, the incidence of immature AVF was 29.56%, affecting 162 of 548 individuals. The five-variable model demonstrated an AUROC value of 0.922, with a 95% confidence interval (CI) of 0.870 to 0.947 in the training dataset, and an AUROC of 0.912, accompanied by a 95% CI of 0.880 to 0.935 in the internal validation dataset. The calibration curve, derived from 1000 bootstrap samples, showed good agreement between predicted and observed outcomes. Additionally, both the DCA and CIC exhibited favorable clinical utility and net benefits. Conclusions: The nomogram prediction model, based on independent risk factors, serves as a valuable tool for accurate prognosis and has potential to aid in establishing and preserving hemodialysis access in elderly diabetic patients, ultimately optimizing their healthcare outcomes. [ABSTRACT FROM AUTHOR]

With the rapid development of flexible displays and wearable electronics, there are a substantial demand for colorless transparent polyimide (CPI) films with different properties. Traditional trial‐and‐error experimental methods are time‐consuming and costly, and density functional theory based prediction of HOMO‐LUMO gap energy also takes time and is prone to varying degrees of error. Inspired by machine learning (ML) applications in molecular and materials science, this paper proposed a data‐driven ML strategy to study the correlation between microscopic molecular mechanisms and macroscopic optical properties. Based on varying degrees of impact of various molecular features on the cutoff wavelength (λcutoff), the ML algorithm is first used to quickly and accurately predict the λcutoff of CPI. Several new CPI films are then designed and prepared based on the key molecular features, and the predicted values of their λcutoff are effectively verified within the experimental error range. The interpretability provided by the model allows to establish correlations between the nine key descriptors identified and their physicochemical meanings. The contributions are also analyzed to the transparency of polyimide films, thereby giving insight into the molecular mechanisms underlying transparency modulation for CPIs. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) materials are highly demanded due to their great potential in optoelectronic and chiroptical elements. However, the preparation of CPL films with high luminescence dissymmetry factors (glum) remains a formidable task, which impedes their practical application in film‐based devices. Herein, a facile strategy to prepare solid CPL film with a high glum through exogenous chiral induction and amplification of liquid crystal polymers is proposed. Amplification and reversion of the CPL appear when the films are annealed at the chiral nematic liquid crystalline temperature and the maximal glum up to 0.30 due to the enhancement of selective reflection. Thermal annealing treatment at different liquid crystalline states facilitates the formation of the chiral liquid phase and adjusts the circularly polarized emission. This work not only provides a straightforward and versatile platform to construct organic films capable of exhibiting strong circularly polarized emission but also is helpful in understanding the exact mechanism for the liquid crystal enhancement of CPL performance. [ABSTRACT FROM AUTHOR]

Introduction: Pulmonary adenoid cystic carcinoma (PACC) is a rare, low-grade malignant salivary gland-type tumor characterized by a dormant onset and slow progression, often leading to misdiagnosis. Due to its rarity, limited cases have been reported in the literature. This report aimed to enhance clinicians' understanding of this infrequent disease. Case Presentation: We present the case of a 41-year-old female patient diagnosed with PACC. Our report provides a comprehensive analysis of the patient's imaging, pathology, and treatment, with a particular focus on immunohistochemical results. Importantly, we emphasize the significance of considering foreign bodies and tumors in the bronchus when encountering asthma-like symptoms unresponsive to conventional treatments. Due to the uncertain etiology and pathophysiology of PACC, there are currently no established guidelines for chemotherapy and radiotherapy. Conclusion: PACC predominantly manifests as bronchial lesions without significant clinical heterogeneity. Therefore, it is crucial to consider foreign bodies and tumors in the bronchus when dealing with asthma-like symptoms, especially in patients without chronic lung disease who do not respond to anti-infective, antispasmodic, and antiasthmatic treatments. Additionally, meticulous examination of lesions is essential for timely diagnosis and intervention, ultimately improving patient survival rates. [ABSTRACT FROM AUTHOR]