On‐Chip Detection of Rolling Circle Amplified DNA Molecules from Bacillus Globigii Spores and Vibrio Cholerae

For the first time DNA coils formed by rolling circle amplification are quantified on‐chip by Brownian relaxation measurements on magnetic nanobeads using a magnetoresistive sensor. No external magnetic fields are required besides the magnetic field arising from the current through the sensor, which makes the setup very compact. Limits of detection down to 500 Bacillus globigii spores and 2 pM of Vibrio cholerae are demonstrated, which are on the same order of magnitude or lower than those achieved previously using a commercial macro‐scale AC susceptometer. The chip‐based readout is an important step towards the realization of field tests based on rolling circle amplification molecular analyses.     

Constraint effect on the near tip stress fields due to difference in plastic work hardening for bi-material interface cracks in small scale yielding

The change in near-tip stress field in Small Scale Yielding (SSY) for cracks located at an interface between two materials with different plastic work hardening is investigated. The difference in hardening is termed hardening mismatch, and is quantified through the parameter n, which is the difference in hardening exponent between the two materials. For cracks in elastic-ideally plastic materials the stress level in front of the crack tip is mainly controlled by the angular extent of the part where the slip lines are curved, often referred to as a centered fan like slip line sector. It is shown that for an elastic-ideally plastic material coupled to a material with non-zero hardening, an increase in stress is observed due to an extension of this centered fan like slip line sector. The angular extension of the centered fan like sector is dependent on the radial distance from the crack tip. Further, the change in stress depends strongly on hardening mismatch, increasing as n increases. For the situation with coupling between two non-zero hardening materials it is shown that the full field stress solution develops in a self-similar manner, but differs from the homogeneous case due to a coupling between the radial and angular stress field dependence. The amplitude of the change in stress field is to a rather good approximation only controlled by the hardening mismatch, n, and is more or less independent of the absolute values of hardening exponent of the two materials.     

Comparison of regression and neural network models for prediction of inspection profiles for aging aircraft

Currently under phase 2 development by the Federal Aviation Administration (FAA), the Safety Performance Analysis System (SPAS) contains alert indicators of aircraft safety performance that can signal potential problem areas for inspectors. The Service Difficulty Reporting (SDR) system is one component of SPAS and contains data related to the identification of abnormal, potentially unsafe conditions in aircraft and/or aircraft components/equipment. SPAS contains performance indicators to assist safety inspectors in diagnosing an airline's safety profile compared with others in the same peer class. This paper details the development of SDR prediction models for the DC-9 aircraft by analyzing sample data from the SDR database that have been merged with aircraft utilization data. Both multiple regression and neural networks are used to create prediction models for the overall number of SDRs and for SDR cracking and corrosion cases. These prediction models establish a range for the number of SDRs outside which safety advisory warnings would be issued. It appears that a data grouping strategy to create aircraft profiles is very effective at enhancing the predictive accuracy of the models. The results from each competing modeling approach are compared and managerial implications to improve the SDR performance indicator in SPAS are provided.     

Oscillating-cup viscometry over an extended viscosity and temperature range

The viscosity of some ZrF₄-based melts is presented and it is demonstrated that it is possible to perform reliable viscosity studies of these highly corrosive melts. Graphite crucibles have been utilized and corrections for the meniscus and the penetration into the crucible have been performed. A general discussion of oscillating-cup viscometry is given and it is shown that the present setup can be used for determination of viscosities in the range from 0.05 to above 500 mPa·s.Paper dedicated to Professor Joseph Kestin.