Gradient’s parameters: 
Make another copy of the tube’s primary layer and apply again
Free Transform option to move the copy to right side the same way it is shown next picture.
The layer’s parameters:
Fill 0% on the layers.
Blending Options>Inner Shadow
The
Ellipse Tool (U) is helpful in darkening out the lowest part of the glass tube.
The layer’s parameters:
Fill 0% on the layers.
Blending Options>Gradient Overlay
