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Additional file 2: Cell-bead co-incubation duration is not critical in the T-cell selection process. The cell-bead co-incubation time, ranging from 30 minutes to 60 minutes, during T cell selection did not affect T cell activation, CAR-T proliferation, and CAR transduction efficiency. (a) CD25 expression percentage in CD3+ cells, (b) CD69 expression percentage in CD3+ cells, and (c) live cell diameter before CD3+ T cell selection and after 48-hour T cell activation. In (a), (b), and (c), an unpaired t-test was used, and a two-tailed P value was calculated between 30 minutes and 45 minutes, 30 minutes and 60 minutes, and 45 minutes and 60 minutes; ns, P>0.3000. (d) Changes in CD25 expression percentage in CD3+ cells, (e) CD69 expression percentage in CD3+ cells, and (f) live cell diameter in the CAR-T manufacturing process. (g) Expansion fold of CAR-T cells after retroviral transduction. (h) CAR expression percentage in CD3+ cells at days 6 and 9 after retroviral transduction.

Additional file 1: Cell density in cell-bead co-incubation is not critical in the T cell selection process. Description: During the cell-bead co-incubation step, cell density (ranging from 4*106 to 10*106 cells/mL) did not affect T cell activation, CAR-T proliferation, and CAR transduction efficiency. (a) CD25 expression percentage in CD3+ cells, (b) CD69 expression percentage in CD3+ cells, and (c) live cell diameter before CD3+ T cell selection and after 48-hour T cell activation. In (a), (b), and (c), an unpaired t-test was used, and two-tailed P value was calculated between 4*106 cells/mL and 7*106 cells/mL, 4*106 cells/mL and 10*106 cells/mL, and 7*106 cells/mL and 10*106 cells/mL; ns, P>0.3000. (d) Changes of CD25 expression percentage in CD3+ cells, (e) CD69 expression percentage in CD3+ cells, and (f) live cell diameter in the CAR-T manufacturing process. (g) Expansion fold of CAR-T cells after retroviral transduction. (h) CAR expression percentage in CD3+ cells at days 6 and 9 after retroviral transduction.

In order to study the superhardness effect of superlattice films, a series of TiN/NbN superlattice films with various modulation periods were synthesized by reactive sputter deposition. X-ray diffraction analysis, transmission electron microscopy, and microhardness analysis were employed to characterize the modulation structure, interface structure and microhardness of these superlattice films. The results show that TiN/NbN films possess good periodic modulation structure and the modulation interfaces are straight and clear. The superlattice films have a face-centered-cubic polycrystalline structure resulting from epitaxial growth. They assume unusual microhardness which can reach a peak value of HK 39.0 GPa at a modulation period of 8.3 nm. It is considered by analysis that the superhardness effect of TiN/NbN superlattice films results from the strengthening effect of an alternating stress field, which is caused by the epitaxial growth of two kinds of materials with different lattice constants.

The polycrystalline NbN/TaN superlattice films have been grown on the substrates of 18-8 stainless steel by reactive magnetron sputtering. The microstructure and microhardness of the superlattice films have been studied with X-ray diffraction (XRD), high resolution transmission electron microscopy (HREM) and microhardness tester. The results showed that the NbN layers are of face cubic and the TaN layers are hexagonal crystal structure in the NbN/TaN superlattice films. The lattice plane (111) of NbN are coherent with the (110) of TaN and the lattice mismatch is 3.18%. The NbN/TaN superlattice film demonstrated superhardness effects. The maximum Knoop hardness value reached 5100 kgf/mm2 with a modulation period from 2.3 nm to 17.0 nm. It was proved that even if NbN layers did not take the same crystal structure as TaN layers, hardness anomalous phenomenon still can be produced as long as the coherent strains exist.