Abstract: A digital video recorder and a video recording and playback method thereof are provided. The digital video recorder includes a first decoding module, a second decoding module, and a video processing module. The first and the second decoding modules decode a video signal into a first image signal and a second image signal. A first command signal is produced when the first image signal is correct, and a second command is produced when the second image signal is correct. The video processing module selectively outputs the first image signal or the second image signal according to the first and the second command.

Abstract: Disclosed herein is a network application device (NAD), comprising a connection assistant module and an application module. The connection assistant module connects to a traversal server, causing the traversal server to receive a physical network address of the NAD. The application module connects to the connection assistant module at a local port number. Also disclosed herein is a network connection system, comprising said traversal server and a first and a second said NAD. The traversal server receives a unique identifier associated with the second NAD when the connection assistant module of the first NAD connects to the traversal server, and provides the same connection assistant module with a physical network address of the second NAD. The application module of the first NAD thereby communicates with the second NAD through the connection assistant module.

Abstract: A method for preparing hydroxylamine, comprising the steps of: (i) pretreating the acidic buffer solution with the compounds having a functional group represented by formula (I), thereby removing metal impurities from the acidic buffer solution; and (ii) reducing nitrate ions in the acidic buffer solution with hydrogen to give hydroxylamine in the presence of catalysts, According to the present invention the selectivity for reducing nitrate ions to give hydroxylamine can be significantly enhanced.

Abstract: A method for preparing hydroxylamine, comprising the steps of: (i) pretreating the acidic buffer solution with the compounds having a functional group represented by formula (I), thereby removing metal impurities from the acidic buffer solution; and (ii) reducing nitrate ions in the acidic buffer solution with hydrogen to give hydroxylamine in the presence of catalysts, According to the present invention the selectivity for reducing nitrate ions to give hydroxylamine can be significantly enhanced.