Provided are a contrast agent for contrast imaging lymph node, which includes iron oxide nanoparticles dispersed and stabilized in an aqueous medium by a mussel adhesive protein-mimetic copolymer, a method for contrast enhanced lymphography using the foregoing contrast agent, and a method for diagnosis of lymph node cancers using the foregoing contrast agent. The transaction server intercepts the custom URI containing customer, item, price andor other relevant information to translate the file request into a transaction record and serve up the appropriate file, possibly from a remote merchant site, for the request and customer. In this way, considering the smaller size of the snow removal mechanism and its maneuverability, it is suitable to assist in removing snow from around the tires of a vehicle that is stuck in the snow, as one example of a suitable use. The F2 gas, which is a cleaning gas, is supplied to the remote plasma-discharge device from an F2 gas cylinder by diluting F2 gas at a given concentration by an inert gas. Wefts of hair may be connected to the longitudinal andor diagonal members and, possibly the peripheral member. The program control apparatus compares the signals produced by each of the devices from the electrical variables to decide whether the failure or the change in the electrical variable of the household appliance is due to a failure of the external power supply system, or due to the household appliance being switched off deliberately.