Table 1 Comparison of ray features (n = 30) between aspen and birch

Rays

 Control

 Thermally modified

Aperture diameter of vessel–ray pit (μm)

8.5

2.8

Number of uniseriate rays per mm²

31.2

10.9

Number of bi- or tri-seriate rays per mm²

–

26.2

Vessel–ray contact (%)

56.8

46.6