136 Program for Research in Science and Engineering Shaping Long Chain Natural Rubber

Authors:

Masako Yang, Matthew Tan, Zhigang Suo

Date Created:

2025-01-01

Course Title:

Professor:

Not specified

About Paper:

Natural rubber is the most widely consumed bioelastomer, with We identify denaturing conditions of temperature and time that annual production reaching billions of tons. The material is a provide sufficient energy to break the non-covalent bonds between network of long rubber chains that are terminated at either ends byproteins but not the chemical bonds of rubber chains. To non-rubber components of proteins and phospholipids. However, demonstrate shaping, we stack, compress, and heat two layers. long chains make natural rubber highly viscous and challenging We present a window of temperature and time within which to shape. Industrial processes thus masticate natural rubber or the shaped samples show similar properties to that of the bulk, use short chain synthetic rubbers. To achieve modulus, these indicating cohesive fusion of layers. These findings challenge short chains are densely crosslinked, producing short strands that the conventional tradeoff between processability and performance, concentrate stress, compromising crack resistance and product providing a viable route to use long chain natural rubber for lifespans. Here, we show a way to preserve long chains during practical application. This will enhance the lifespan of rubber shaping. By denaturating proteins, strong non-covalent bonds products, minimize waste, and provide alternatives to highly are broken, enabling long rubber chains to flow for shaping. processed, fossil-fuel derived synthetic rubbers. Evaluation of Stroke-Induced Upper Limb Movement Impairment During Activities of Daily Living Sarah Yee, Prabhat Pathak, Conor Walsh Harvard College | Lowell House | Mechanical Engineering | 2028 Stroke is a leading cause of death in the United States, with are on an ordinal scale (e.g., FMA is rated 0, 1, and 2 e.g.), over 795,000 cases each year. The most common stroke-related causing a floor and ceiling effect that lacks the fine resolution to disability is arm paresis: partial paralysis or weakness affecting detect subtle kinematic deviations. This is essential for tracking over 80% of survivors, often long-term, making it difficult to changes in motor impairment post-stroke during ADLs that require incorporate the affected arm to perform activities of daily living spontaneous, naturalistic upper limb movements. (ADLs). Hence, we aim to understand movement impairment in individuals Clinical and robotic rehabilitation strategies focus on encouragingpost-stroke during ADLs. We leverage an optical motion capture theuseoftheaffectedarmindailyactivities. However, individuals system to record three-dimensional upper body movements during post-stroke often avoid using the impaired limb due to weakness ADLs, including self-feeding (e.g., drinking water) and grooming or poor coordination, relying instead on compensatory movements (e.g., brushing teeth), essential tasks for functional independence. like excessive trunkmotion. This disuseexacerbates motor decline We will perform a kinematic analysis to evaluate differences in and hinders recovery. Historically, clinicians and researchers havejoint range of motion, hand coordination, and compensatory trunk used clinical scales like the Fugl-Meyer Assessment (FMA) and movement between the affected and unaffected arms. the Action Research Arm Test (ARAT). The FMA evaluates motor impairment through specific, isolated upper limb movements, Ultimately, this research will provide guidelines for precision while the ARAT measures performance on timed functional tasks. rehabilitation during ADLs and support the iterative design of at- home wearable robots capable of delivering task-specific, fine- These results are more variable and subjective, as therapists’ tuned assistance. experience levels can affect outcomes. Additionally, these scales Modeling the Chemokine and Cellular Niche of CD4+ Tissue-Resident

Abstract:

Natural rubber is the most widely consumed bioelastomer, with We identify denaturing conditions of temperature and time that annual production reaching billions of tons. The material is a provide sufficient energy to break the non-covalent bonds between network of long rubber chains that are terminated at either ends byproteins but not the chemical bonds of rubber chains. To non-rubber components of proteins and phospholipids. However, demonstrate shaping, we stack, compress, and heat two layers. long chains make natural rubber highly viscous and challenging We present a window of temperature and time within which to shape. Industrial processes thus masticate natural rubber or the shaped samples show similar properties to that of the bulk, use short chain synthetic rubbers. To achieve modulus, these indicating cohesive fusion of layers. These findings challenge short chains are densely crosslinked, producing short strands that the conventional tradeoff between processability and performance, concentrate stress, compromising crack resistance and product providing a viable route to use long chain natural rubber for lifespans. Here, we show a way to preserve long chains during practical application. This will enhance the lifespan of rubber shaping. By denaturating proteins, strong non-covalent bonds products, minimize waste, and provide alternatives to highly are broken, enabling long rubber chains to flow for shaping. processed, fossil-fuel derived synthetic rubbers. Evaluation of Stroke-Induced Upper Limb Movement Impairment During Activities of Daily Living Sarah Yee, Prabhat Pathak, Conor Walsh Harvard College | Lowell House | Mechanical Engineering | 2028 Stroke is a leading cause of death in the United States, with are on an ordinal scale (e.g., FMA is rated 0, 1, and 2 e.g.), over 795,000 cases each year. The most common stroke-related causing a floor and ceiling effect that lacks the fine resolution to disability is arm paresis: partial paralysis or weakness affecting detect subtle kinematic deviations. This is essential for tracking over 80% of survivors, often long-term, making it difficult to changes in motor impairment post-stroke during ADLs that require incorporate the affected arm to perform activities of daily living spontaneous, naturalistic upper limb movements. (ADLs). Hence, we aim to understand movement impairment in individuals Clinical and robotic rehabilitation strategies focus on encouragingpost-stroke during ADLs. We leverage an optical motion capture theuseoftheaffectedarmindailyactivities. However, individuals system to record three-dimensional upper body movements during post-stroke often avoid using the impaired limb due to weakness ADLs, including self-feeding (e.g., drinking water) and grooming or poor coordination, relying instead on compensatory movements (e.g., brushing teeth), essential tasks for functional independence. like excessive trunkmotion. This disuseexacerbates motor decline We will perform a kinematic analysis to evaluate differences in and hinders recovery. Historically, clinicians and researchers havejoint range of motion, hand coordination, and compensatory trunk used clinical scales like the Fugl-Meyer Assessment (FMA) and movement between the affected and unaffected arms. the Action Research Arm Test (ARAT). The FMA evaluates motor impairment through specific, isolated upper limb movements, Ultimately, this research will provide guidelines for precision while the ARAT measures performance on timed functional tasks. rehabilitation during ADLs and support the iterative design of at- home wearable robots capable of delivering task-specific, fine- These results are more variable and subjective, as therapists’ tuned assistance. experience levels can affect outcomes. Additionally, these scales Modeling the Chemokine and Cellular Niche of CD4+ Tissue-Resident

Source:

Harvard / Harvard College | Quincy House | Biomedical Engineering | 2027 / 2025

Topics:

rubber, chain, long, movement, natural, adls, engineering, shaping, upper, limb, impairment, provide

Co-authors:

@masakoyang390 , @matthewtan391 , @zhigangsuo392