Design of Thermally Activated Delayed Fluorescence Materials: Transition from Carbonyl to Amide-Based Acceptors.

Benzophenone skeletons containing a carbonyl unit (O=C) have been widely used as electron acceptors in the thermally activated delayed fluorescence (TADF) materials. Herein, we present a novel molecular design concept for TADF materials by transitioning from a carbonyl to an amide (O=C-N) skeleton as the acceptor. The amide unit, compared to its carbonyl counterpart, offers a more stable electronic configuration. Leveraging this insight, we have developed a series of high-performance TADF molecules based on benzoyl carbazole and carbazoline acceptors. These molecules exhibit exceptionally small singlet-triplet energy gaps and pronounced aggregation-enhanced emission properties, achieving photoluminescence quantum yields in neat films as high as 99%. Consequently, these materials serve as efficient emitters in non-doped organic light-eimtting diodes (OLEDs), reaching a maximum quantum efficiency (EQEmax) of up to 26.0%, significantly higher than the 17.0% obtained with benzophenone acceptor-based TADF molecules. Additionally, they have been used as TADF hosts in narrowband red fluorescent OLEDs, setting a record-high EQEmax of 22.4%.

Quantification of testicular fat content: the value of evaluating testicular function after cryptorchidism surgery.

BACKGROUND: To investigate the correlation between testicular fat content (TFC) and sex hormone levels in patients with cryptorchidism and its value in assessing postsurgical testicular function. METHODS: Pelvic MRI with the mDIXON Quant sequence was performed on 23 cryptorchidism patients and 15 normal controls. The TFC before and after surgery was measured and compared. The correlations between cryptorchid TFC and testosterone (TSTO), follicle-stimulating hormone (FSH), and estradiol (E2) levels were analyzed, as was the specificity of TFC and each hormone for assessing testicular function after surgery. RESULTS: The preoperative cryptorchid TFC (3.06% ± 0.74) was higher than that of the normal controls (1.36% ± 0.49). TSTO was negatively correlated with the cryptorchid TFC (r = -0.698), while FSH and E2 were positively associated with the cryptorchid TFC (r = 0.658, 0.676). Cryptorchid TFC after surgery (2.01% ± 0.55) was lower than the preoperative TFC, but hormone levels were not significantly different. The TFC after surgery (0.864) had a larger AUC value than did TSTO (0.639), FSH (0.597), and E2 (0.586). CONCLUSION: Noninvasive quantification of cryptorchid TFC using the mDIXON Quant sequence is more specific than hormone levels for assessing postsurgical changes in testicular function. IMPACT: The cryptorchid testicular fat content is significantly higher than the normal testicular fat content. Cryptorchid testicular fat content is negatively correlated with presurgical serum TSTO levels and positively correlated with presurgical FSH and E2 levels. Pre- and postoperative changes in cryptorchid testicular fat content change are more sensitive than changes in TSTO, FSH, or E2 levels. Noninvasive cryptorchid testicular fat content quantified by the mDIXON Quant sequence is more specific than serum TSTO, FSH, and E2 levels for assessing changes in testicular function after cryptorchidism surgery.

Nitrogen Effects Endowed by Doping Electron-Withdrawing Nitrogen Atoms into Polycyclic Aromatic Hydrocarbon Fluorescence Emitters.

Unveiling innovative mechanisms to design new highly efficient fluorescent materials and, thereby, fabricate high-performance organic light-emitting diodes (OLEDs) is a concerted endeavor in both academic and industrial circles. Polycyclic aromatic hydrocarbons (PAHs) have been widely used as fluorescent emitters in blue OLEDs, but device performances are far from satisfactory. In response, we propose the concept of "nitrogen effects" endowed by doping electron-withdrawing nitrogen atoms into PAH fluorescence emitters. The presence of the n orbital on the imine nitrogen is conducive to promoting electron coupling, which leads to increased molar absorptivity and an accelerated radiative decay rate of emitters, thereby facilitating the Förster energy transfer (FET) process in the OLEDs. Additionally, electronically withdrawing nitrogen atoms enhances host-guest interactions, thereby positively affecting the FET process and the horizontal orientation factor of the emitting layer. To validate the "nitrogen effects" concept, cobalt-catalyzed multiple C-H annulation has been utilized to incorporate alkynes into the imine-based frameworks, which enables various imine-embedded PAH (IE-PAH) fluorescence emitters. The cyclization demonstrates notable regioselectivity, thereby offering a practical tool to precisely introduce peripheral groups at desired positions with bulky alkyl units positioned adjacent to the nitrogen atoms, which were previously beyond reach through the Friedel-Crafts reaction. Blue OLEDs fabricated with IE-PAHs exhibit outstanding performance with a maximum external quantum efficiency (EQEmax) of 32.7%. This achievement sets a groundbreaking record for conventional blue PAH-based fluorescent emitters, which have an EQEmax of 24.0%.

Biomarkers of preschool children with autism spectrum disorder: quantitative analysis of whole-brain tissue component volumes, intelligence scores, ADOS-CSS, and ages of first-word production and walking onset.

BACKGROUND: Preschooling is a critical time for intervention in children with autism spectrum disorder (ASD); thus, we analyzed brain tissue component volumes (BTCVs) and clinical indicators in preschool children with ASD to identify new biomarkers for early screening. METHODS: Eighty preschool children (3-6 years) with ASD were retrospectively included. The whole-brain myelin content (MyC), white matter (WM), gray matter (GM), cerebrospinal fluid (CSF), and non-WM/GM/MyC/CSF brain component volumes were obtained using synthetic magnetic resonance imaging (SyMRI). Clinical data, such as intelligence scores, autism diagnostic observation schedule-calibrated severity scores, age at first production of single words (AFSW), age at first production of phrases (AFP), and age at walking onset (AWO), were also collected. The correlation between the BTCV and clinical data was evaluated, and the effect of BTCVs on clinical data was assessed by a regression model. RESULTS: WM and GM volumes were positively correlated with intelligence scores (both P < 0.001), but WM and GM did not affect intelligence scores (P = 0.116, P = 0.290). AWO was positively correlated with AFSW and AFP (both P < 0.001). The multivariate linear regression analysis revealed that MyC, AFSW, AFP, and AWO were significantly different (P = 0.005, P < 0.001, P < 0.001). CONCLUSIONS: This study revealed positive correlations between WM and GM volumes and intelligence scores. Whole-brain MyC affected AFSW, AFP, and AWO in preschool children with ASD. Noninvasive quantification of BTCVs via SyMRI revealed a new visualizable and quantifiable biomarker (abnormal MyC) for early ASD screening in preschool children.