| 1 |
What is the primary advantage of using organic radical contrast agents over traditional gadolinium-based contrast agents (GBCAs) in MRI?
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Lower toxicity |
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7 |
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| 2 |
Which property of dendrimers makes them suitable as scaffolds for organic radical contrast agents?
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Monodisperse and well-defined macromolecular structure |
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7 |
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| 3 |
What are nitroxides commonly used for in the context of MRI contrast agents?
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Providing color contrast |
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7 |
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| 4 |
Which type of dendrimer has been fully functionalized with TEMPO radicals and studied for MRI contrast agents?
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PPI dendrimers |
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7 |
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| 5 |
What challenge do nitroxides face that limits their widespread use as MRI contrast agents?
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Rapid in vivo reduction and low paramagnetic relaxivity |
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7 |
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| 6 |
A dendrimer-based contrast agent contains 48 TEMPO radicals, each contributing 0.14 mM⁻¹ s⁻¹ to relaxivity. What is the total relaxivity of this dendrimer-based contrast agent?
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6.7 mM⁻¹ s⁻¹ |
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7 |
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| 7 |
If a fourth-generation dendrimer with 32 PROXYL radicals has a relaxivity of 5 mM⁻¹ s⁻¹, what is the relaxivity per PROXYL radical?
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0.15 mM⁻¹ s⁻¹ |
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7 |
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| 8 |
A dendrimer-based MRI contrast agent releases its radical at a rate of 0.5 mM/day. If the initial concentration of the radical is 10 mM, how many days will it take for the concentration to reduce to 2 mM?
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14 days |
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7 |
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| 9 |
If the relaxivity of a G1-Tyr-PROXYL dendrimer is 2.9 mM⁻¹ s⁻¹ and that of Gd-DTPA is 3.2 mM⁻¹ s⁻¹, what is the percentage difference in relaxivity between the two agents?
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11.5% |
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7 |
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| 10 |
A dendrimer scaffold improves water solubility by attaching PEG chains. If the original dendrimer has a solubility of 5 g/L and attaching PEG increases the solubility by 60%, what is the new solubility of the dendrimer?
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8 g/L |
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| 11 |
What is the primary reason for using dynamic amplification factor (DAF) in the analysis of steel truss bridges?
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To account for the effects of sudden member failure |
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7 |
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| 12 |
Which method is traditionally used to calculate the DAF for steel truss bridges, and why is it considered conservative?
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Finite element analysis because it is too accurate |
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| 13 |
What is the damping ratio commonly used in the conventional DAF calculation for steel truss bridges?
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4% |
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| 14 |
In the context of this study, what does the empirical equation for DAF primarily depend on?
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Maximum bending moment |
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| 15 |
Which types of loading are considered in the analysis of progressive collapse in steel truss bridges?
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Dead load and live load |
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| 16 |
A member in a steel truss bridge fractures and causes a maximum dynamic stress of 450 MPa. If the yield stress of the member is 315 MPa, what is the dynamic amplification factor (DAF) based on stress?
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1.25 |
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| 17 |
If the maximum static stress in a bridge member after a fracture is 280 MPa and the corresponding dynamic stress is 392 MPa, what is the dynamic amplification factor (DAF)?
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1.40 |
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7 |
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| 18 |
A bridge member has a yield stress of 250 MPa. During a dynamic event, the maximum stress reaches 375 MPa. What is the stress ratio (𝜎 𝑑𝑦𝑛𝑎𝑚𝑖𝑐 / 𝜎 𝑦𝑖𝑒𝑙𝑑)
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1.6 |
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| 19 |
What is the mechanical property that ensures a stent remains flexible and stable in blood vessels?
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Stress |
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| 20 |
If the Young's modulus of a stent material is 200 GPa and the applied stress is 50 MPa, what is the strain experienced by the stent?
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0.001 |
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7 |
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