Domain: Engineering — Biomedical Engineering
Target concept: Chitosan-based Biomedical Composite Materials

Video generation prompt: Display two images side by side, with the chitosan-based hemostatic material sample placed in swine whole blood on the left, and the same chitosan-based hemostatic material sample placed in normal saline solution on the right, to observe how each material's physical state changes over time.

Evaluation guide:
(i) Target concept: Selective osmotic and ionic swelling response of chitosan-based biomaterials in physiological blood versus inert saline medium.
Minimum mechanism: Chitosan is a cationic polysaccharide whose protonated amine groups bind anions (e.g., Cl⁻) and proteins in blood, triggering water influx and hydrogel expansion; in isotonic saline, ion concentration balances osmotic pressure, preventing net water uptake.
(ii)Storyline: [Phase 1] Two identical chitosan samples are simultaneously placed into adjacent containers: left receives swine whole blood (dark red, opaque), right receives normal saline (colorless, transparent). [Phase 2] Within seconds, left-side material undergoes visible volumetric expansion (no dissolution, no color shift) while right-side material remains morphologically invariant. [Phase 3] Both samples remain stationary under fixed frontal view; contrast between swollen vs. non-swollen states is continuously observable and unambiguous. Perspective constraint: strictly top-down or frontal orthographic view; no oblique angles, no depth cues that obscure side-by-side comparison. Visibility constraint: entire material surface and liquid interface must be fully in focus and unoccluded.

Manual:
Experimental Procedure
1. Place identical chitosan-based hemostatic material samples into two identical containers.
2. Fill left container with swine whole blood; fill right container with normal saline.
3. Hold both containers side by side in fixed frontal view for 10 seconds.
Observation of Experimental Phenomena
Left-side material swells visibly (increased volume/size); right-side material shows no swelling (unchanged shape/size).
Summary of Experimental Principles
Chitosan-based hemostatic materials exhibit selective swelling in blood due to ionic interaction with plasma proteins and erythrocytes, while remaining dimensionally stable in isotonic saline — a key functional property enabling rapid hemostasis without overhydration.

Prompt Grounding rubric:
level_1: Neither container of liquid is shown; no chitosan sample is visible in either container; blood and saline are not distinguishable from each other or are entirely absent; the two setups are not shown together in one frame.
level_2: Two containers appear together, but they are stacked or offset rather than level with each other; a chitosan sample is visible in at least one container, but only one of the two liquids (blood or saline) is actually present, or the two liquids are not distinguishable by color/opacity from each other.
level_3: Two containers are shown level with each other in the same frame; each contains an identically shaped chitosan sample; the left container holds an opaque, dark-red liquid consistent with whole blood, and the right container holds a clear, colorless liquid consistent with saline; the assignment (blood on left, saline on right) matches the setup.
level_4: All elements of score 3 are present AND: the two chitosan samples look identical to each other before either liquid is added (same size, shape, and color); the two containers are of matching size and shape; nothing (gloves, labels, text) blocks the view of either sample or liquid; the camera holds a single, front-facing view of both containers throughout.
level_5: All elements of score 4 are present AND: the two containers sit at equal height and equal distance from the frame's center, with the same spacing on each side; there is no splashing, bubbling, or floating debris visible during the observation period; neither sample moves from its resting position in its container for the duration of the clip.

Scientific and Causal Correctness rubric:
level_1: Neither sample shows any visible size or shape change in either liquid; or both samples swell by a similar amount in both blood and saline; or a sample visibly falls apart or dissolves in either liquid rather than swelling or staying the same.
level_2: Only one sample changes size, but it is the wrong one: specifically, the sample in saline swells while the sample in blood shows no change; or the visible change is a color or transparency shift rather than an actual increase in the sample's size.
level_3: The sample in whole blood (left) visibly increases in size relative to how it looked when first placed in the liquid; the sample in saline (right) keeps its original size and shape; the size difference between the two samples is clearly visible to the eye by the end of the clip.
level_4: All elements of score 3 are present AND: the size increase on the blood side is a swelling of the material itself, not liquid pooling around it or the container appearing to bulge; the swollen sample stays in one piece, with no visible cracking or crumbling; the saline-side sample shows no bulging, softened edges, or wet sheen suggesting even slight swelling.
level_5: All elements of score 4 are present AND: the blood-side sample swells evenly across its whole surface, without one section ballooning while another stays flat; the saline-side sample looks the same at the end of the clip as it did at the start, with the same edge sharpness and surface appearance; the swelling on the blood side begins only after the sample touches the blood, not before, and does not disappear once it has occurred.

Spatiotemporal Consistency rubric:
level_1: The material appears to jump from one container to the other between frames; a container's position on screen changes abruptly; the room lighting flashes, flickers, or the shadows jump to a new position without cause; the material appears to rotate or flip on its own; the camera angle suddenly changes (a pan, zoom, or tilt) partway through.
level_2: The material visibly shifts position within its container from one frame to the next without anything touching it; a container's edge appears to wobble; the overall brightness of the scene noticeably flickers up and down; the motion of placing the samples looks jerky, as if frames were dropped.
level_3: Neither sample teleports or disappears at any point; neither container shows a sudden break or deformation; the lighting stays steady, with no flash or sudden shadow jump; the camera viewpoint does not move; the placement of each sample into its liquid is a single smooth motion; there is no visible stutter in the playback.
level_4: All elements of score 3 are present AND: each sample is placed into its liquid in one continuous motion, without pausing partway and resuming; the containers' rims stay aligned with the edges of the frame the whole time; background elements (e.g., the countertop behind the containers) do not shift relative to the containers; neither container nor sample appears to stretch, warp, or change proportions between frames.
level_5: All elements of score 4 are present AND: the sample in each container shows no visible shaking, drifting, or vibration once placement is complete; the liquid surface in each container stays still, with no ripples or waves after the sample settles; no object's edges appear blurred or smeared from one frame to the next; the two containers keep the same visual sharpness and clarity throughout the clip.