Diffraction gratings affect the absolute phase of light in a way that is not obvious from the usual derivation of optical paths using the grating equation. For example, consider light which encounters first one and then the second of two parallel gratings. If one grating is moved parallel to its surface, the phase of the light diffracted from the grating pair is shifted by 2pi each time the grating is moved by one grating constant, even though the geometric path length is not altered by the motion. This additional phase shift must be included when incorporating diffraction gratings in interferometers.

Fractional gas holdup was measured in 0.57, 1.0, and 1.5 m i.d. vessels. Pitched blade downflow turbines (PTD) were used as the impeller. Design details of the impeller, such as the impeller diameter (0.22 T to 0.5 T) and blade width (0.25 D to 0.4 D), were studied. The effect of sparger type, geometry and size on fractional gas hold‐up has been investigated in detail. Four different types of spargers (pipe, conical, ring and concentric ring spargers) were used. Sparger location was varied for all the types studied. Further, design details of the ring sparger, which gave the highest hold‐up were then studied in detail. These included ring diameter, number of holes and hole size. All the reported correlations for fractional gas hold‐up in mechanically agitated gas‐liquid reactors were tested and compared. A better correlation has been developed for pitched blade turbines.

Culinary heritage, an edible identity, is a manifestation of the culture and urban life of a place. Most traditional food practices continue to flourish in historic urban settings as a result of the interplay between the spatial design and the socio-cultural practices. This essay explores these interconnections between gastronomic and architectural heritage through the lens of traditional urbanism. It emphasizes the importance of gastronomic culture within wider urban networks, bringing vibrancy and community engagement to traditional shared public spaces which host a wide range of activities. This symphony of traditions can also help us to achieve a sustainable and richer cultural life. They could become a model to upgrade modern spatial design practices, which are usually based on mere convenience or individual benefit.