ABSTRACT
We report the synthesis of a longitudinally helical molecular nanocarbon, hexabenzoheptacene (HBH), along with its dimethylated derivative (HBH-Me), which are composed of six benzene rings periodically benzannulated to both zigzag edges of a heptacene core. This benzannulation pattern endows the resulting nanocarbons with a helical heptacene core and local aromaticity, imparting enhanced solubility and stability to the system. The chiral HBH-Me adopts a more highly twisted conformation with an end-to-end twist angle of 95°, enabling the separation of the enantiomers. Both HBH and HBH-Me can be facilely oxidized into their corresponding dications, which exhibit enhanced planarity and aromaticity upon loss of electrons. Notably, both longitudinally helical nanocarbons readily promote solid state packing into two-dimensional (2D) arrangement. Single-crystal microbelts of HBH-Me show hole mobility up to 0.62â cm2 V-1 s-1, illustrating the promising potential of these longitudinally helical molecules for organic electronic devices.
ABSTRACT
The purpose of this study was to evaluate the prognostic value of lymph node ratio (LNR) in patients with gastric cancer liver metastasis (GCLM) who received combined surgical resection. A retrospective analysis of 46 patients from two hospitals was conducted. Patients were dichotomized into two groups (high LNR and low LNR) by the median value of LNR. The overall survival (OS) and recurrence-free survival (RFS) were analyzed by the Kaplan-Meier method with the log-rank test. The Cox proportional hazard model was used to carry out the subsequent multivariate analyses. And the relationship between LNR and clinicopathological characteristics was assessed. The cut-off value defining elevated LNR was 0.347. With a median follow-up of 67.5 months, the median OS and RFS of the patients were 17 and 9.5 months, respectively. Six patients survived for >5 years after surgery. Patients with higher LNR had significantly shorter OS and RFS than those with lower LNR. In the multivariate analyses, higher LNR and multiple liver metastatic tumors were identified as the independent prognostic factors for both OS and RFS. Elevated LNR was significantly associated with advanced pN stage (Pâ<0.001), larger primary tumor size (Pâ=â0.046), the presence of microvascular invasion (Pâ=â0.008), and neoadjuvant chemotherapy (Pâ=â0.004). LNR may be prognostic indicator for patients with GCLM treated by synchronous surgical resection. Patients with lower LNR and single liver metastasis may gain more survival benefits from the surgical resection. Further prospective studies with reasonable study design are warranted.