As people increasingly play online games, numerous new features have been proposed to increase players' log-on time at online gaming sites. However, few studies have investigated why people continue to play certain online games or which design features are most closely related to the amount of time spent by players at particular online gaming sites. This study proposes a theoretical model using the concepts of customer loyalty, flow, personal interaction, and social interaction to explain why people continue to play online network games. The study then conducts a large-scale survey to validate the model. Finally, it analyzes current online games to identify design features that are closely related to the theoretical concepts. The results indicate that people continue to play online games if they have optimal experiences while playing the games. This optimal experience can be attained if the player has effective personal interaction with the system or pleasant social interactions with other people connected to the Internet. Personal interaction can be facilitated by providing appropriate goals, operators and feedback; social interaction can be facilitated through appropriate communication places and tools. This paper ends with the implications of applying the study results to other domains such as e-commerce and cyber communities.

The effects of lowering pH by an acidulant (citric acid) on the formation of acrylamide in fried and baked corn chips and in french fries were studied by using a GC/MS. The 0.2% citric acid treatments induced 82.2% and 72.8% inhibition of acrylamide formation in fried and baked corn chips, respectively. Dipping potato cuts in 1% and 2% citric acid solutions for 1 h before frying showed 73.1% and 79.7% inhibition of acrylamide formation in french fries. In the experiment of heating 1 mL solution containing asparagine and glucose in phosphate buffers, by lowering the pH from 7.0 to 4.0, 99.1% inhibition of acrylamide formation was achieved. This is the first finding of an effective, simple, and practical way to limit the acrylamide formation in real foods.

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FIG. 2. Light-induced modification of the electronic structure. a,b Snapshots of the trARPES spectra along the kx momentum direction and for kz = 0 Å−1 . The data have been measured at 11 K with a probe photon energy of 10.75 eV and an absorbed pump fluence of 0.4 mJ/cm 2 . (a) Snapshot before photoexcitation (t < 0). At the Γ point of the Brillouin zone (kx = 0 Å−1 ), the flat anti-bonding VB is located around -0.16 eV, whereas the bonding VB appears around -0.65 eV. (b) Snapshot measured at the maximum of the pump-probe response (t = 0.3 ps). Upon photoexcitation, the VB is depleted in intensity and broadens significantly. Spectral weight is transfered above EF and accumulates close to Γ. c-f, Evolution of the photoexcited state (at t = 0.3 ps) along kx at representative kz momenta, as indicated in the labels. Note that the color scale is different from that of panels (a,b). The spectral weight above EF assumes a W-like shape consistent with the dispersion of the CB. The VB and CB never crosses each other and thus the gap size remains finite in the whole kx-kz momentum space around Γ. The white lines denote the energy-momentum dispersion calculated at the GW level (Fig. 1b). A rigid shift of -84 meV has been applied to the VB to account for the underestimated gap resulting from the GW method. The calculated dispersions have an excellent match with the experimental findings.

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