Enhanced Sensitivity in Nanopore Sensing of Cancer Biomarkers in Human Blood via Click Chemistry

Cancer biomarkers are expected to be indicative of the occurrence of certain cancer diseases before the tumors form and metastasize. However, many biomarkers can only be acquired in extremely low concentrations, which are often beyond the limit of detection (LOD) of current instruments and technologies. A practical strategy for nanopore sensing of cancer biomarkers in raw human blood down to the femtomolar level is developed here. This strategy first converts the detection of cancer biomarkers to the quantification of copper ions by conducting a sandwich assay involving copper oxide nanoparticles. The released Cu²⁺ is then taken to catalyze the “click” reaction which ligates a host–guest modified DNA probe. Finally, this DNA probe is subjected to single‐channel recordings to afford the translocation events that can be used to derive the concentrations of the original biomarkers. Due to the amplification effects of nanoparticle loadings and the “click” reaction, the LOD of this strategy can be as low as the subfemtomolar level. Further, the acid treatment step could effectively eliminate the interferences from plasma proteins in raw human blood and make the strategy highly suitable for the detection of cancer biomarkers in clinical samples.     

New method for determining P‐S‐N curves in terms of equivalent fatigue lives

A new method for determining the P‐S‐N curves is proposed by the probabilistic analysis of the mixed samples that are composed of the testing fatigue lives and equivalent fatigue lives. The equivalent fatigue lives at each level are converted from all the testing data at all the testing levels according to the equivalent fatigue failure probability, where the life distributions are determined by the medians of logarithmic fatigue lives at respective levels and a unified coefficient of variation. Comparison results of the P‐S‐N curves of 2024‐T3 and A356.0‐T6 alloys with the different methods indicate that the new method can determine the high‐precision P‐S‐N curves with different sample sizes of the S‐N testing data, and can save testing time and improve testing efficiency, especially for the situation of large‐scatter S‐N testing data.     

Reliability analysis of metal‐composite adhesive joints under debonding modes I,II, and I/II using the results of experimental and FEM analyses

In the present study, the experimental and finite element (FE) analyses are first carried out to investigate the deboning behavior of metal‐composite adhesive joints under modes of I and mode II loading. To conduct an FE on the debonding propagation, cohesive zone method (CZM), as well as maximum nominal stress and energy criteria, is applied. In the reliability analysis, to achieve the probability of debonding growth (PODG), limit state functions are formulated based on the energy release rate. To that end, the first‐order reliability method (FORM), the second‐order reliability method (SORM), and the Monte Carlo simulation (MCS) are used to calculate the PODG. The effect of initial debonding length on the PODG in all mentioned modes is investigated. Results obtained from reliability analysis reveal that the random variables including the initial debonding length, width, and thickness are the most sensitive variables to ascertain the PODG.