Abstract: The present invention relates to a recombinant bacterium wherein said bacterium comprises an optogenetic interaction switch to control cellular functions, in particular wherein said bacterium is a recombinant gram-negative bacterium comprising a type III secretion system, wherein the activity of said type III secretion system is light-dependent, and to methods for controlling cellular functions in a bacterium using such an optogenetic interaction switch.

Abstract: A density measuring device has a hollow body (1) for receiving a fluid medium. The hollow body includes at least two parallel tube sections (6, 6a, 7, 7a) with a connecting line (9) on a first end thereof that connects the tube sections in a U shape. On a second end, the hollow body has a clamping element (2) with a clamping tube (5, 5a) terminating each of the tube sections. An excitation device including a piezoelectric element (4) oscillates the tube sections and a sensor device, also with a piezoelectric element (4a), detects a variable characterizing an excited vibration. Both piezoelectric elements are attached to a contact area (3, 3a) of the clamping element. The contact areas are disposed on the proximal end of the clamping element relative to the tube sections. Each contact area extends across both clamping tubes.

Abstract: A density measuring device has a hollow body (1) for receiving a fluid medium. The hollow body includes at least two parallel tube sections (6, 6a, 7, 7a) with a connecting line (9) on a first end thereof that connects the tube sections in a U shape. On a second end, the hollow body has a clamping element (2) with a clamping tube (5, 5a) terminating each of the tube sections. An excitation device including a piezoelectric element (4) oscillates the tube sections and a sensor device, also with a piezoelectric element (4a), detects a variable characterizing an excited vibration. Both piezoelectric elements are attached to a contact area (3, 3a) of the clamping element. The contact areas are disposed on the proximal end of the clamping element relative to the tube sections. Each contact area extends across both clamping tubes.