Thermal Annealing Effects on Long-lived Fluorenol Room Temperature Phosphorescence for Styrene Detection.

Fluorene derivatives have been widely developed in OLEDs because of its efficient fluorescence quantum efficiency, but for which unique rigid biphenyl planar structure and large conjugated system, we hypothesize that they have a great potential for room temperature phosphorescence (RTP) applications, and confirmed this conjecture by subjecting polyvinyl alcohol (PVA) and phosphors to thermal annealing. The cross-linked structure formed during thermal annealing judiciously modulates the phosphorescence emission characteristics of the fluorenol with the synergistic interaction between PVA and fluorenol. Specifically, the lifetime exhibited a substantial increase from 1352.2 ms to 2874.1 ms, accompanied by a quantum yield augmentation from 4.8% to 11.3%, which substantiate that cross-linked induced by thermal annealing effectively amplifies the phosphorescent intensity and stability of the phosphors, facilitating ultralong phosphorescent emission at ambient conditions. Furthermore, an effective probe based on this film is developed for its highly sensitive, quantitative and immediate detection of volatile organic compounds. This investigation not only proffers a novel paradigm for the development of advanced RTP materials but also imparts insightful considerations for optimizing the performance of polymers in conjunction with functional materials, encompassing bioimaging, sensing, and optoelectronic devices.

Unique Visualization Growth Process of Long-Lived Room Temperature Phosphorescence in Polymer System.

Recently, embedding organic phosphors into the polyvinyl alcohol (PVA) matrix has emerged as a convenient strategy to obtain efficient long-lived room temperature phosphorescence (RTP) via forming strong intermolecular hydrogen bonds with organic phosphors to minimize nonradiative relaxations. Regrettably, it is discovered that PVA is unable to trigger RTP emission when a novel functional phosphor THBE containing six extended biphenyl formaldehyde arms is doped into PVA matrix. Surprisingly, the excellent long-lived RTP emission can be easily obtained by doping THBE into PVA analogs, poly(vinyl alcohol-co-ethylene) (PVA-co-PE). The unique visualization growth process (i.e., white streak generation) of long-lived RTP is observed by UV light-driven aggregation of functional molecules THBE in PVA-co-PE matrix. The phosphorescent intensity of the luminescent film is enhanced by 55 times, from 729 to 40,785 a.u., and its phosphorescence lifetime is increased by 38 times, from 37.08 to 1415.41 ms. Due to the dynamically reversible RTP performance, as well as the permeability, flexibility, and wrinkle-free properties of the luminescent film, it can be utilized to create cutting-edge information storage devices.

Use of a curved needle to facilitate four-in-one nerve block performance after total knee arthroplasty in elderly patients: a randomized clinical trial.

BACKGROUND: Peripheral nerve block is the main analgesic technique for total knee arthroplasty (TKA) in elderly patients. Accurate delivery of the needle tip to the target nerve under ultrasound-guided is a prerequisite for successful nerve block. Failed needle-tip positioning in sciatic nerve (SN) or medial femoral cutaneous nerve (MFCN) block can be due to anatomical structure shadow. The aim of the study was to compare curved and straight needles in regard to the time needed to perform the nerve block for TKA in elderly patients. METHODS: One hundred patients aged 65 to 80 years and ASA II-III, BMI 18-30 kg/m2, who underwent general anesthesia for unilateral TKA received the nerve block under ultrasound guidance after surgery, were included in this study. All patients were randomly divided into two groups (N.=50): straight needle group (Group S) and curved needle group (Group C). The primary outcome measure was the time needed to successfully perform the nerve block. Secondary outcomes included the number of attempts and needle redirections to achieve nerve blockade, as well as the satisfaction of patients and anesthesiologists. RESULTS: Compared with group S, the performance time was shorter in group C (488.0±44.9 vs. 517.8±42.1 P=0.001). The procedural pain score was less in group C (1.8±0.4 vs. 2.4±0.6, P=0.000). The satisfaction score of the anesthesiologist (3.4±0.8 vs. 2.4±0.6, P=0.000) and patients (3.4±0.7 vs. 1.9±0.6, P=0.000) were higher in the curved needle group compared with the straight needle group. CONCLUSIONS: The use of a curved needle can reduce the time required to perform the nerve block, with reduction in the number of attempts and needle redirections. Curved needle also resulted in lesser procedural pain and higher satisfaction compared with the straight needle.