BackgroundEarly-onset gastric cancer (EOGC, ≤45 years old) is characterized with increasing incidence and more malignant phenotypes compared with late-onset gastric cancer, which exhibits remarkable immune cell infiltration and is potential immunotherapeutic population. Till now, restricted survival information of EOGC is available due to limited case numbers. This study established a novel nomogram to help evaluate cancer-specific survival (CSS) of EOGC patients who underwent gastrectomy, and may provide evidence for predicting patients’ survival.MethodsWe retrospectively enrolled a cohort containing 555 EOGC cases from five independent medical centers in China, among which 388 cases were randomly selected into a training set while the other 167 cases were assigned into the internal validation set. Asian or Pacific Islander (API) patients diagnosed with EOGC during 1975-2016 were retrieved from the SEER database (n=299) and utilized as the external validation cohort. Univariate and multivariate analyses were conducted to test prognostic significances of clinicopathological factors in the training set. Accordingly, two survival nomogram models were established and compared by concordance index (C-index), calibration curve, receiver operating characteristics (ROC) curves and decision curve analyses (DCA).ResultsThe 5-year CSS rate of training cohort was 61.3% with a median survival time as 97.2 months. High consistency was observed on calibration curves in all three cohorts. Preferred nomogram was selected due to its better performance on ROC and DCA results. Accordingly, a novel predicative risk model was introduced to better stratify high-risk EOGC patients with low-risk patients. In brief, the 5-year CSS rates for low-risk groups were 92.9% in training set, 83.1% in internal validation set, 89.9% in combined NQSQS cohort, and 85.3% in SEER-API cohort. In contrast, the 5-year CSS rates decreased to 38.5%, 44.3%, 40.5%, and 36.9% in the high-risk groups of the four cohorts above, respectively. The significant survival difference between high-risk group (HRG) and low-risk group (LRG) indicated the precise accuracy of our risk model. Furthermore, the risk model was validated in patients with different TNM stages, respectively. Finally, an EOGC web-based survival calculator was established with public access, which can help predict prognosis.ConclusionsOur data provided a precise nomogram on predicting CSS of EOGC patients with potential clinical applicability.

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Contact angle is one of the most important indexes to evaluate the hydrophobicity of solid surface. In order to explore the wetting characteristics of droplets on anisotropic solid surfaces, including contact angle, droplet radius, droplet height, contact radius, contact area and projected area, an ellipsoidal droplet contact angle model was established. By collecting the droplet size parameters of FKM prepared by template method, the correctness of the theoretical model was verified. Among them, the maximum error between the theoretical value of droplet radius and the actual measured value is 4.3%, and the maximum error of droplet projected area is 2.1%. It is found that the contact angle is inversely proportional to the droplet-solid contact radius and contact area, and directly proportional to the projected area of the droplet. In addition, for the same droplet on the surface of the same solid material, it is observed that the contact radius between the droplet and the solid is small in the direction of large contact angle. This discovery is helpful to explain the hydrophobic mechanism of the material surface with anisotropic contact angle.

In order to study the influence of two-stage vulcanization process on the hydrophobic characteristics of FKM, superhydrophobic surfaces were prepared based on template method (1000 mesh screen, 1600 mesh screen and 2000 mesh screen), and six kinds of FKM with micro-rough surface were prepared by one-stage vulcanization and two-stage vulcanization process, respectively.At first, the influence of two-stage vulcanization process on the physical and