Abstract: A mesh chair back includes a loop-shaped frame, an elastic mesh part, a waist support unit, and a smooth separating plate; the loop-shaped frame has left and right upright portions; the elastic mesh part is positioned over and secured on the loop-shaped frame; the waist support unit is arranged behind the elastic mesh part, and connected to the left and the right upright portions of the loop-shaped frame at two ends in an up and down displaceable manner; the smooth separating plate is positioned between the mesh part and the waist support unit for preventing the waist support unit from rubbing and causing wear to the mesh part while the waist support unit is being adjusted in height; the waist support unit props the separating plate and the mesh part forwards such that the separating plate and the mesh part each has a forwards protruding portion.

Abstract: A chair is provided with adjustable armrests. The chair has two vertical guiding bars, each of which extends down from a lateral side of a back thereof, and each of which has engaging trenches spaced along it. Each armrest has a connecting space extending vertically through a rear end thereof, and is up and down movably connected to a corresponding guiding bar at the connecting space thereof. A lever is pivoted to a bottom of the rear end of each armrest. Each lever has an engaging projection, which can be fitted into one of the engaging trenches of corresponding guiding bar to make the armrest unmovable by means of pivoting the lever to the locking position. When the levers are in the unlocking position, the armrests can be adjusted in height.

Abstract: A cathode for use in an electron gun includes a base metal comprising Ni as a principal component and a two-layer electron emissive material disposed on the base metal. The inner layer is comprised of an alkaline earth metal oxide and 1-30 wt. % W and may further include 0.1-5 wt. % of a rare earth metal oxide. The outer layer is comprised of an alkaline earth metal oxide and may further include 0.1-5 wt. % of a rare earth metal oxide. The outer electron emissive layer provides stability for the cathode. In the degassing and activation process, W and Ni react at high temperatures to form a Ni4W fine crystal structure. An intermediate layer, such as Ba2SiO4, is dispersed in the Ni4W fine crystal structure in operation. Free barium is produced in reactions between the various cathode components to provide a high current density for the cathode. The normalized electron emission current value of the cathode does not decrease with use, even over extended periods of operation.