Domain: Healthcare — Medicine
Target concept: Stability Testing of the Drug (Photostability Test)

Video generation prompt: Two test tubes are placed side by side on the table. The left test tube contains 1 mL of riboflavin solution and is exposed to strong light, while the right test tube contains an equal volume of the same solution and is kept in the dark (light-protected) at room temperature. The camera is focused on the solutions in both test tubes, recording a time-lapse that compresses several hours of exposure into a short continuous clip.

Evaluation guide:
(i) Target concept: Light-induced chemical degradation of photosensitive pharmaceutical compounds.
Minimum mechanism: Riboflavin must absorb photons from incident light, triggering bond cleavage or oxidation that reduces conjugated chromophore system → measurable decrease in visible yellow absorbance; this process requires photon flux but no thermal input, and is inhibited by light exclusion.
(ii)Storyline: Frame 0–1: Two identical upright test tubes, filled with equally colored yellowish liquid, side-by-side under neutral ambient light. Frame 2–3: Strong directional light activates on left tube only; right tube enters stable dim/shadowed condition. Frame 4–8: Left tube liquid progressively lightens uniformly; right tube liquid color remains invariant. Frame 9–10: Final state shows clear, stable color contrast (left paler, right unchanged), with both tubes fully visible, stationary, and optically coherent. Perspective: Fixed frontal close-up on liquid columns; no occlusion; all causal agents (light source, shadow boundary) visually anchored and persistent.

Manual:
Experimental Procedure
1. Place two identical empty test tubes side-by-side on a flat table.
2. Add exactly 1 mL of riboflavin solution to each tube.
3. Expose left tube to strong directional light; place right tube in a light-protected (dark) location at the same room temperature, e.g., under an opaque cover or in shadow, not refrigerated.
4. Fix camera to record a time-lapse of both tubes' liquid surfaces, compressing several hours of exposure into a short continuous clip.
Observation of Experimental Phenomena
Left tube solution gradually becomes paler (less yellow) than right tube solution; both remain transparent and homogeneous; no precipitation or phase change occurs.
Summary of Experimental Principles
Riboflavin undergoes photodegradation under strong light, causing loss of yellow color; light exclusion (independent of temperature) preserves color stability — demonstrating the photostability requirement in drug storage.

Prompt Grounding rubric:
level_1: No test tubes are visible, or only one test tube is present, or the two tubes aren't shown next to each other, or neither tube visibly contains the riboflavin solution, or the camera shows something other than the solutions (hands, labels, background), or there is no visible light-versus-dark contrast set up between the two tubes at all.
level_2: Two tubes sit side by side, but at least one of the following is missing: both actually contain liquid; the left tube has a visible light source or bright glare on it; the right tube looks shielded from light (in shadow, under a cover, or in a darkened area); or the shot is dominated by something irrelevant like a hand or a spinning table.
level_3: Two matching test tubes sit side by side on the same surface, each holding what looks like the same volume of pale yellow liquid; the left tube clearly has strong, direct light hitting it, shown as a bright highlight or glare on the tube or liquid; the right tube clearly lacks that direct light and instead sits in shadow or under a light-blocking cover; the camera stays fixed on both liquid columns the whole time.
level_4: Level 3's setup holds, and additionally there is no cover, foil, or diffuser sitting between the light source and the left tube's liquid; the right tube shows no stray glare or hotspot leaking over from the left tube's light; both tubes stand upright in the same orientation; no extra containers, labels, or on-screen text crowd the shot.
level_5: Level 4's clean setup holds, and additionally the left tube shows a distinctly brighter lit patch on its surface or liquid compared with the right tube, the right tube sits in a visibly dimmer zone such as its own cast shadow or the edge of its cover, both tubes are visible from base to liquid surface with nothing blocking the view, and there is no lens flare, blown-out overexposure, or color fringing obscuring either tube's true liquid color.

Scientific and Causal Correctness rubric:
level_1: No visible color difference ever shows up between the tubes; or both tubes fade by the same amount; or a color difference appears before the light is even turned on; or the right (dark) tube changes color while the left stays the same; or either liquid turns cloudy, solid, or precipitates.
level_2: A color difference appears, but backwards: the dark tube gets paler while the lit tube stays the same or gets darker; or the color shifts to some other hue entirely, such as blue, green, purple, or turns cloudy, instead of simply fading toward colorless; or only the dark tube changes; or a difference appears and then disappears again before the clip ends.
level_3: By the end of the clip, the light-exposed left tube's liquid looks noticeably paler or less yellow than the dark right tube's liquid; both liquids stay clear and evenly colored with no cloudiness or layering; once a difference appears it only grows or holds steady and never reverses; the difference is visible without needing to zoom in.
level_4: Level 3's one-directional fading holds, and additionally the left tube's paling happens gradually across the clip rather than jumping suddenly from one frame to the next; the right tube's color stays essentially unchanged throughout; both tubes start out the same shade of yellow before the light turns on; nothing about the glass itself, such as staining or a warped meniscus, fakes the appearance of a color change.
level_5: Level 4's gradual, one-sided fading holds, and additionally the left tube's paling looks even across the whole visible liquid column rather than showing an obvious top-to-bottom color split; the right tube shows no detectable shift in hue or brightness compared to its very first frame; both tubes' liquid surfaces keep a consistent curve and shine with no sign of evaporation; no unrelated color tint, such as magenta or cyan, creeps into either tube from lighting or rendering.

Spatiotemporal Consistency rubric:
level_1: One of the test tubes is absent for a frame or two and then simply back in place, or it suddenly changes size or shifts position with no transition; the lighting flicks on and off or swings to a new direction mid-clip; the camera pans, tilts, or zooms; a shadow appears or disappears even though nothing around it moved to cause that.
level_2: A tube's base shifts sideways by more than its own width between frames; the liquid meniscus jumps vertically by more than 10% of the tube's height without a corresponding pour or spill; a highlight on a tube's surface jumps to a new spot without the light itself visibly moving; a shadow on the right tube appears or vanishes without anything moving to block or unblock the light.
level_3: Both tubes stay fixed in position and orientation the whole time; the light's brightness and direction don't change; the shadows stay put and match the light's position; the camera's viewpoint never shifts; both liquid surfaces stay essentially flat and undisturbed, with no sloshing, dripping, or bubbling.
level_4: Level 3's steady tubes and lighting hold, and additionally each tube's glass wall keeps a consistent thickness and curve rather than warping or distorting; the reflected highlights on both tubes move together consistently with the ambient light rather than drifting on their own; neither tube's edge nor its liquid surface shows tearing, ghosting, or a doubled or blurred outline between frames.
level_5: Level 4's clean rendering holds, and additionally the apparent depth between the two tubes doesn't shift as if the camera had moved; the specular highlights keep the same angle relative to each tube's shape throughout; the overall brightness doesn't pulse or strobe between frames; and neither tube's glass shows any bulging, bending, or fluctuating transparency.