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Mode I fracture toughness is an important material parameter of rock. To date, a number of laboratory methods have been developed to measure the mode I fracture toughness. Although the fracture toughness values measured by different methods have been compared in many previous studies, the effect of the specimen configuration and pre-existing notch shape on the fracture toughness value and the associated cracking characteristics have not been comprehensively studied. In the present study, the failure modes and mode I fracture toughness of Kowloon granite, a major type of granite in Hong Kong, are studied experimentally based on the chevron bend (CB), semi-circular bend (SCB) and cracked chevron notched semi-circular bend (CCNSCB) methods. The fracture toughness measured by the SCB test is much lower (56.5% lower) than that measured with the CCNSCB test. The measured CB fracture toughness is between the SCB and CCNSCB results. The failure modes of specimens containing the chevron notch (CB and CCNSCB specimens) are found to differ from those containing the straight-through notch (SCB specimens), especially with respect to the post-failure behavior. The cracking mechanism of the SCB and CCNSCB is studied macroscopically and microscopically. The results show that the straight-through notch and chevron notch, which are the most commonly used notch shapes adopted in various mode I fracture toughness tests, have significant effects on the cracking behavior and crack characteristics. Further investigation on the thin sections prepared from the specimens after the mode I fracture toughness tests provides us with new insights into the microscopic characteristics of tensile cracks in granite under mode I loading condition. [ABSTRACT FROM AUTHOR]

Genetic mutations can cause life-threatening diseases such as cancers and sickle cell anemia. Gene detection is thus of importance for disease-risk prediction or early diagnosis and treatment. Apart from genetic defects, gene detection techniques can also be applied to gene-related diseases with high risk to human health such as human papillomavirus (HPV) infection. HPV infection has been strongly linked to cervical cancer. To achieve a high-throughput HPV gene detection platform, the flow-through hybridization system appears to be one of the commercialized diagnostic techniques for this purpose. The flow-through hybridization technique is based on a vacuum-guided flow of DNA fragments which is continuously directed toward the oligoprobes that are immobilized on the testing membrane. However, the conventional colorimetric method and signal read-out approach suffers a problem of low sensitivity. On the contrary, fluorescence approaches allow more sensitive detection and broad sensing ranges. In this work, a fluorescent dye HCAP, which possesses aggregation-induced emission (AIE) properties and is responsive to alkaline phosphatase, was developed and applied to the flow-through hybridization platform to achieve HPV genome diagnosis of clinical samples. Also, an automatic membrane reader was constructed based on the AIE-based diagnosis platform which can identify the diagnostic result of patient DNA with a total concordance rate of 100% in the clinical trial. [ABSTRACT FROM AUTHOR]