ABSTRACT
Almost all colloidal quantum dots (QDs) exhibit undesired photoluminescence (PL) blinking, which poses a significant obstacle to their use in numerous luminescence applications. An in-depth study of the blinking behavior, along with the associated mechanisms, can provide critical opportunities for fabricating high-quality QDs for diverse applications. Here the blinking of a large series of colloidal QDs is investigated with different surface ligands, particle sizes, shell thicknesses, and compositions. It is found that the blinking behavior of single alloyed CdSe/ZnS QDs with a shell thickness of up to 2 nm undergoes an irreversible conversion from Auger-blinking to band-edge carrier blinking (BC-blinking). Contrastingly, single perovskite QDs with particle sizes smaller than their Bohr diameters exhibit reversible conversion between BC-blinking and more pronounced Auger-blinking. Changes in the effective trapping sites under different excitation conditions are found to be responsible for the blinking type conversions. Additionally, changes in shell thickness and particle size of QDs have a significant effect on the blinking type conversions due to altered wavefunction overlap between excitons and effective trapping sites. This study elucidates the discrepancies in the blinking behavior of various QD samples observed in previous reports and provides deeper understanding of the mechanisms underlying diverse types of blinking.
ABSTRACT
Lead halide perovskite quantum dots (QDs) are promising materials for next-generation photoelectric devices because of their low preparation costs and excellent optoelectronic properties. In this study, the blinking mechanisms and the intrinsic quantum-confined Stark effect (IQCSE) in single organic-inorganic hybrid CH3 NH3 PbBr3 perovskite QDs using single-dot photoluminescence (PL) spectroscopy is investigated. The PL quantum yield-recombination rates distribution map allows the identification of different PL blinking mechanisms and their respective contributions to the PL emission behavior. A strong correlation between the excitation power and the blinking mechanisms is reported. Most single QDs exhibit band-edge carrier blinking under a low excitation photon fluence. While under a high excitation photon fluence, different proportions of Auger-blinking emerge in their PL intensity trajectories. In particular, significant IQCSEs in the QDs that exhibit more pronounced Auger-blinking are observed. Based on these findings, an Auger-induced IQCSE model to explain the observed IQCSE phenomena is observed.
ABSTRACT
BACKGROUND: Laryngeal cancer is a common malignancy of head and neck cancer, with increasing morbidity and mortality in our country. It is reported that AGP1 can act as a serum marker for several diseases and cancers. In this study, we evaluated the diagnostic value of AGP1 in laryngeal cancer. METHODS: The serum AGP1 levels of 119 laryngeal carcinoma patients and 68 healthy volunteers were detected by real-time PCR (qRT-PCR) and ELISA. Chi-square test was applied to evaluate the association between AGP1 mRNA levels and clinical characteristics. To determine the diagnostic value of AGP1, ROC curve was constructed. RESULTS: The expression level of AGP1 was higher in laryngeal cancer patients than that in healthy group (P<0.001). Moreover, its mRNA level was significantly associated with tumor size (P=0.004), TNM stage (P=0.006), and distant metastasis (P=0.018). ROC curve demonstrated that AGP1 could be used for laryngeal cancer diagnosis with AUC value of 0.924, combing with the sensitivity of 78.8% and specificity of 89.7%. The optimal cutoff value was 0.725. CONCLUSION: AGP1 is up-regulated and correlated with tumor progression in laryngeal cancer patients. AGP1 may be a potential diagnostic biomarker for laryngeal cancer.
ABSTRACT
OBJECTIVE: To study the surgical management of metastatic disease in the conjunctive area between the neck and thorax and its efficacy. METHODS: Fourteen cases with metastatic node disease in the area between neck and thorax were collected and analysed. Eleven tumors were from the thyroid cancer, and the other three were from the hypopharyngeal cancer, esophagual cancer and malignant pheochromocytoma, respectively. The clavicle was displaced or resected, and the upper half of the manubrium might also be resected when necessary. The recurrent laryngeal nerve and phrenic nerve were exposed and protected. The metastatic disease was completely removed with the internal jugular and/or the brachiocephalic vein resected or spared, depending on the disease condition. RESULTS: In 10 cases with metastases from the thyroid, no local recurrence was found within the follow-up period from 2 to 5 years. In contrast, no patient with metastatic disease from hypopharyngeal or esophageal cancer survived more than 11 months. No serious complications were found in this group. CONCLUSIONS: The surgical treatment of node metastases in the conjunctive area between neck and thorax from the well-developed thyroid cancer has promising effect and is comparatively safe.
