Abstract: The present invention provides an anhydrous crystal of polymyxin B1 sulfate, polymyxin B2 sulfate or a mixture thereof and a preparation method thereof. The preparation method comprises using an organic solvent to precipitate a solid from a saturated solution of polymyxin B1 sulfate, polymyxin B2 sulfate or a mixture thereof, drying it under vacuum to obtain an anhydrous crystal of polymyxin B1 sulfate, polymyxin B2 sulfate or a mixture thereof.

Abstract: The present invention provides a polymyxin B sulfate crystal and a preparation method thereof. Said method comprises the following steps of: adsorbing a polymyxin B fermentation liquid with a resin, and adding sulfuric acid or acidic ethanol for desorbing; concentrating to obtain a saturated solution of polymyxin B sulfate; and using an organic solvent to precipitate a crystal from the saturated solution, filtering and drying to obtain the polymyxin B sulfate crystal.

Abstract: A simulated eye is provided. The tilt switch comprises an electrically insulating housing with a chamber formed therein. The chamber is defined by a bottom surface and a surrounding surface. The tilt switch also includes a plurality of contact terminals, each of which comprises an inner terminal portion and an outer terminal portion. Each inner terminal portion protrudes out of the surrounding surface of the chamber and extends in a direction substantially parallel to the bottom surface. The tilt switch further includes an electrically conductive moving member placed in a space defined by the cap, the bottom surface, and the plurality of contact terminals. The electrically conductive moving member is capable of simultaneously contacting with at most two of the plurality of contact terminals.

Abstract: A simulated eye is provided. The tilt switch comprises an electrically insulating housing with a chamber formed therein. The chamber is defined by a bottom surface and a surrounding surface. The tilt switch also includes a plurality of contact terminals, each of which comprises an inner terminal portion and an outer terminal portion. Each inner terminal portion protrudes out of the surrounding surface of the chamber and extends in a direction substantially parallel to the bottom surface. The tilt switch further includes an electrically conductive moving member placed in a space defined by the cap, the bottom surface, and the plurality of contact terminals. The electrically conductive moving member is capable of simultaneously contacting with at most two of the plurality of contact terminals.