An angle-adjustable backrest device includes a backrest frame and an angle-adjusting device for connecting the backrest frame to a chair. The described particles are capable of delivering polynucleotides to cells from the peripheral circulation with subsequent release from endosomes. The first antenna may have a first axis. The circuitry is electrically coupled with the antenna elements to maintain tuning and isolation of the elements when the housing is distorted in three dimensions. The bridges of memory material have sub-lithographic dimensions.