A thin film transistor array substrate for a digital photo-detector is provided. A comparator compares a bandgap reference voltage and temperature sensor voltage and trips the circuit when the temperature voltage is less than the bandgap reference voltage. Two or more experiments in different layers are allowed to be performed on the same query, and for any given layer, at most one experiment is allowed to be performed on the same query. Reflector means for reflecting signals from sources previously injected are provided between each source and its circulator. The chiral diamine may be used to prepare catalysts suitable for use in transfer hydrogenation reactions.