Abstract: A method for preparing an L-erythrobiopterin compound is provided. The L-erythrobiopterin compound has a structure represented by formula (I), and is mainly prepared from a compound having a structure represented by formula (II) or (III) through dihydroxylation. The preparation method of the L-erythrobiopterin compound is high in production efficiency, low in cost, environmentally friendly, and suitable for industrial production.

Abstract: A method for preparing an L-erythrobiopterin compound is provided. The L-erythrobiopterin compound has a structure represented by formula (I), and is mainly prepared from a compound having a structure represented by formula (II) or (III) through dihydroxylation. The preparation method of the L-erythrobiopterin compound is high in production efficiency, low in cost, environmentally friendly, and suitable for industrial production.

Abstract: The invention relates to an antenna system mounted onto a printed circuit board, said antenna system comprising first and second radiating elements, an antenna feeding element connected to an antenna feeding pad of the printed circuit board, a ground return element connected to a ground pad of the printed circuit board. A third radiating element having first and second ends, the first end of the third radiating element is connected to the second end of the second radiating element. The third radiating element, the second radiating element, the ground return element and the antenna feeding element are arranged to form an inverted-F antenna.

Abstract: An antenna for use in a wireless system is described. The antenna includes a radiating element, at least one signal input portion and at least one signal output portion. The at least one signal input portion and the at least one signal output portion are both coupled to the radiating element. A portion of the radiating element is positioned outward from and parallel to an edge of the printed circuit board when the radio frequency antenna is attached to a surface of the printed circuit board of the wireless system.

Abstract: A new method of preparing memantine hydrochloride, comprising the following steps: reacting 1-bromo-3,5-dimethyl adamantane and urea/formic acid, with formic acid also acting as the solvent; hydrolyzing with aqueous inorganic acid; alkalifying, extracting and acidifying with hydrochloric acid; finally collecting target compound. The method uses inexpensive raw materials and is performed in homogeneous phase under mild conditions. It can achieve high yield and good product purity, and is suitable for macrochemistry. The purity of crude product is 99.0%, and reaches 99.98% after first recrystallization, yield: 69.5%, mp: 332 C (DSC).

Abstract: A novel method of preparing memantine hydrochloride, comprising the following steps: reacting 1-bromo-3,5-dimethyl adamantane and urea/formic acid, with formic acid also acting as the solvent; hydrolyzing with aqueous inorganic acid; alkalifying, extracting and acidifying with hydrochloric acid; finally collecting target compound. The method uses inexpensive raw materials and is performed in homogeneous phase under mild conditions. It can achieve high yield and good product purity, and is suitable for macrochemistry. The purity of crude product is 99.0%, and reaches 99.98% after first recrystallization, yield: 69.5%, mp: 332 C (DSC).