Interfaces: The Next NDE Challenge

Nondestructive evaluation, as practiced in the 1960’s, attempted to detect (but was often unable to characterize) the existence of defects in engineering structures. Qualitative criteria were used in the assessment of defect significance and the determination of accept/reject decisions. Advances in elasto-plastic fracture mechanics during the 1970’s focused attention upon the defect size and orientation- if these could be measured, then fracture mechanics was capable of quantitative structural integrity evaluation. The papers presented in this conference series during the 1980’s trace the considerable advances of quantitative nondestructive evaluation in satisfying this measurement need. Nowadays, for monolithic materials with well defined fracture toughness, the overconservative rejection criteria of the past are beginning to be replaced by “retirement for cause” concepts

Ultrasound-Mediated DNA Transformation in Thermophilic Gram-Positive Anaerobes

Thermophilic, Gram-positive, anaerobic bacteria (TGPAs) are generally recalcitrant to chemical and electrotransformation due to their special cell-wall structure and the low intrinsic permeability of plasma membranes. transformants/µg of methylated DNA. Delivery into X514 cells was confirmed via detecting the kanamycin-resistance gene for pIKM2, while confirmation of pHL015 was detected by visualization of fluorescence signals of secondary host-cells following a plasmid-rescue experiment. Furthermore, the foreign β-1,4-glucanase gene was functionally expressed in X514, converting the host into a prototypic thermophilic consolidated bioprocessing organism that is not only ethanologenic but cellulolytic.In this study, we developed an ultrasound-based sonoporation method in TGPAs. This new DNA-delivery method could significantly improve the throughput in developing genetic systems for TGPAs, many of which are of industrial interest yet remain difficult to manipulate genetically

Repurposing hyperpolarization-activated cyclic nucleotide-gated channels as a novel therapy for breast cancer.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are members of the voltage-gated cation channel family known to be expressed in the heart and central nervous system. Ivabradine, a small molecule HCN channel-blocker, is FDA-approved for clinical use as a heart rate-reducing agent. We found that HCN2 and HCN3 are overexpressed in breast cancer cells compared with normal breast epithelia, and the high expression of HCN2 and HCN3 is associated with poorer survival in breast cancer patients. Inhibition of HCN by Ivabradine or by RNAi, aborted breast cancer cell proliferation in vitro and suppressed tumour growth in patient-derived tumour xenograft models established from triple-negative breast cancer (TNBC) tissues, with no evident side-effects on the mice. Transcriptome-wide analysis showed enrichment for cholesterol metabolism and biosynthesis as well as lipid metabolism pathways associated with ER-stress following Ivabradine treatment. Mechanistic studies confirmed that HCN inhibition leads to ER-stress, in part due to disturbed Ca2+ homeostasis, which subsequently triggered the apoptosis cascade. More importantly, we investigated the synergistic effect of Ivabradine and paclitaxel on TNBC and confirmed that both drugs acted synergistically in vitro through ER-stress to amplify signals for caspase activation. Combination therapy could suppress tumour growth of xenografts at much lower doses for both drugs. In summary, our study identified a new molecular target with potential for being developed into targeted therapy, providing scientific grounds for initiating clinical trials for a new treatment regimen of combining HCN inhibition with chemotherapy

Modified blister tests for evaluation of thin flexible membrane adhesion on rigid substrate

The blister test geometry commonly used for the measurement of interfacial work of adhesion W has been re-examined and new fracture mechanics analyses are given for thin flexible membranes on rigid substrates in which the stretching deformations are predominant. Two loading configurations are considered. (1) The blister is pressurized under an internal expansion of a fixed mass of working gas. Here stable crack propagation and multiple measurements per specimen are allowed. (2) The blister is loaded by a shaft at its apex, which also gives stable interface crack propagation. The fracture mechanics analyses are verified with simple experiments using sticky tapes on an aluminium plate based on these two test methods. Additional shaft-loaded blister experiments of nylon 6 films on surface treated aluminium substrates have also been studied and compared to the double cantilever geometry

HIGH-STRENGTH, HIGH FRACTURE-TOUGHNESS FIBER COMPOSITES WITH INTERFACE CONTROL - A REVIEW

The subject of improving the fracture toughness of fibre composites is receiving significant attention because a critical design criterion in damage tolerant fibre composites is the possession of a sufficiently high fracture energy absorption capability, particularly under impact loading conditions. For a given brittle-fibre/brittle-matrix composite, high strength requires a strong interfacial bond, but this may lead to a low fracture energy absorption. However, by proper control of the physical and mechanical properties of the fibre-matrix interface high strength characteristics can be combined with high toughness. In order to fully utilise the potential of such composites without introducing a reduction in strength, it is necessary to understand the failure mechanisms leading to eventual fracture. This paper reviews the existing theories of fracture toughness of fibre composites and the various methods for improving the fracture toughness by means of interface control. Conclusions and generalisations which can be drawn from the literature are presented with discussions of areas in which further research is required