Compounds of the formula 1in which R, R, R7-R11, X, n1 and n3 are as defined herein. In some embodiments, the unloader can include an unloader arm movable within the container, a first chain coupled to the unloader arm and movable to unload material from the container, and a second chain coupled to the unloader arm and positioned to engage material within the container upon movement of the unloader arm. The circuit further comprises a first comparator for providing the first logical level when a third signal difference between the first output signal and the second output signal is greater than a third threshold value, and for providing the second logical level when the third signal difference is smaller than the third threshold value. The preview document includes instructions such, that when it is viewed in a web browser, it can present the identity of style properties influencing a presentation of an area in the document by selecting the area. The input of the short circuited switch detection device is coupled to the semiconductor switching device, wherein the short circuited switch detection device detects a short circuit in the semiconductor switch switching device. The luminescent layer includes a first sublayer made of a first metal complex and a second sublayer made of a second metal complex.