design of experiments reaction kinetics

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Design of experiments on the kinetics of the water-gas shift reaction

1961, AIChE Journal

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Recently global attempt are focused on replacing gas flaring by environmentally friendly technologies, such as gas to liquid (GTL) technology. The main aim of this practice is preventing waste of energy and decreasing the emission of CO2 and other harmful by-product gases. In order to fulfill this goal, improvement of GTL process efficiency seems necessary. For this purpose, in this work the performance of two different configurations is compared in basis of hydrogen component. In both, refinery purge gases are used as a feedstock where enter to reaction side of a hydrogen perm-selective membrane reformer. In the first configuration, steam reformer reactor is located outside the Fischere-Tropsch synthesis loop while in the second one is placed inside the loop. A portion of generated hydrogen in the reformer is permeated through the membrane as a byproduct and the remaining is utilized in FischereTropsch synthesis reactions. The simulation results of the aforementioned loops show that the second configuration is better than the first one of operation. The results of second configuration show 87% hydrogen utilization in FeT reactions and 11% hydrogen production in steam reformer reactions and also 2% hydrogen exit by off gas in separator. Further advantages of this alternative are namely, lessening in CO2 emission rate with a value of 0.8 for the first configuration ones and less than 0.33 to that of flaring, and more than 8430 barrels per day of heavy fraction hydrocarbons containing gasoline and butane fraction for a specified value (about 356.5 MMscfd) of purge gases.

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One of the main issues facing mankind in this century is the global warming which is induced by the increasing concentration of carbon dioxide and other greenhouse gases in the atmosphere. A promising process for controlling the atmospheric CO2 level is prevention of combustion in flares. In the present work, a novel GTL loop is proposed to convert the natural gas wasted by a gas refinery to higher molecular weight hydrocarbons. The process proposes an alternative method instead of conventional gas-burning flares, aims to minimize CO2 emissions and produce liquid fuel such as gasoline. For this purpose, purged natural gas is converted to synthesis gas in a novel hydrogen-permselective membrane reactor with recycle stream and then it is converted to liquid fuel in Fischer-Tropsch membrane reactor. In this configuration, a loop is constructed by returning and mixing a portion of the product with the original feed through a recycle stream. This approach produces large amounts of higher molecular weight hydrocarbons, hydrogen production and decreases environmental impacts owing to purge gases emission. The simulation results of the aforesaid loop, show decrease in CO2 emission rate with a value of 1/10 to that of flaring with production of 0.018 kgmol/s of hydrogen and more than 90 barrels per day of heavy fraction hydrocarbons containing gasoline and butane fraction for a specified value of (about 4 MMscfd) purge gases.

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Efficient and accurate experimental design for enzyme kinetics: Bayesian studies reveal a systematic approach

Affiliation.

• 1 Bioinformatics, Division of Cell and Molecular Biology, School of Animal and Microbial Sciences, The University of Reading, Whiteknights, Berkshire, RG6 6AJ, Reading, UK. [email protected]
• PMID: 12628698
• DOI: 10.1016/s0165-022x(02)00183-5

In areas such as drug development, clinical diagnosis and biotechnology research, acquiring details about the kinetic parameters of enzymes is crucial. The correct design of an experiment is critical to collecting data suitable for analysis, modelling and deriving the correct information. As classical design methods are not targeted to the more complex kinetics being frequently studied, attention is needed to estimate parameters of such models with low variance. We demonstrate that a Bayesian approach (the use of prior knowledge) can produce major gains quantifiable in terms of information, productivity and accuracy of each experiment. Developing the use of Bayesian Utility functions, we have used a systematic method to identify the optimum experimental designs for a number of kinetic model data sets. This has enabled the identification of trends between kinetic model types, sets of design rules and the key conclusion that such designs should be based on some prior knowledge of K(M) and/or the kinetic model. We suggest an optimal and iterative method for selecting features of the design such as the substrate range, number of measurements and choice of intermediate points. The final design collects data suitable for accurate modelling and analysis and minimises the error in the parameters estimated.

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Modulating composite colloidal particle morphology by reaction kinetics in seeded-growth

• Chemical routes to materials
• Published: 17 June 2024

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• Firdavsi Tursunov   ORCID: orcid.org/0009-0007-6713-0271 1 , 2 , 3 &
• Dong Qiu 1 , 2  

This article presents a systematic investigation into the seed-mediated growth of composite colloidal particles, illustrating a range of controlled sizes and morphologies. We developed a facile approach to modulate the morphology of composite particles in seeded-growth by varying the solvent composition during the growth of TiO 2 and SiO 2 colloidal particles. Core–shell type morphologies were observed during the growth of inert nanoparticles on active seed surfaces. In contrast, active nanoparticles facilitated the growth of anisotropic nanoparticles. Our experiments also demonstrated that the growth size of nanoparticles could be tuned by altering the concentration of precursors. We obtained two types of nanoparticles with distinct sizes: larger particles and smaller ones, with the latter originating from secondary formation. The variety of morphologies observed in seed nanoparticles confirms the applicability of our hypothesis on seeded growth.

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Acknowledgements

The authors thank all students for their research contributions and exceptional enthusiasm in this research direction. Firdavsi Tursunov acknowledges scholarship support from the CAS-TWAS President’s Ph.D. Fellowship for International Students.

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State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China

Firdavsi Tursunov & Dong Qiu

University of Chinese Academy of Sciences, Beijing, 100190, China

Samarkand State University named after Sharof Rashidov, 140104, Samarkand, Uzbekistan

Firdavsi Tursunov

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Tursunov, F., Qiu, D. Modulating composite colloidal particle morphology by reaction kinetics in seeded-growth. J Mater Sci (2024). https://doi.org/10.1007/s10853-024-09875-z

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DOI : https://doi.org/10.1007/s10853-024-09875-z

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68 Best Chemistry Experiments: Learn About Chemical Reactions

Whether you’re a student eager to explore the wonders of chemical reactions or a teacher seeking to inspire and engage your students, we’ve compiled a curated list of the top 68 chemistry experiments so you can learn about chemical reactions.

While the theories and laws governing chemistry can sometimes feel abstract, experiments bridge the gap between these concepts and their tangible manifestations. These experiments provide hands-on experiences illuminating the intricacies of chemical reactions, molecular structures, and elemental properties.

1. Covalent Bonds

By engaging in activities that demonstrate the formation and properties of covalent bonds, students can grasp the significance of these bonds in holding atoms together and shaping the world around us.

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2. Sulfuric Acid and Sugar Demonstration

Through this experiment, students can develop a deeper understanding of chemical properties, appreciate the power of chemical reactions, and ignite their passion for scientific exploration.

3. Make Hot Ice at Home

Making hot ice at home is a fascinating chemistry experiment that allows students to witness the captivating transformation of a liquid into a solid with a surprising twist.

4. Make a Bouncing Polymer Ball

This hands-on activity not only allows students to explore the fascinating properties of polymers but also encourages experimentation and creativity.

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5. Diffusion Watercolor Art

This experiment offers a wonderful opportunity for students to explore the properties of pigments, observe how they interact with water, and discover the mesmerizing patterns and textures that emerge.

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6. Exploding Baggie

The exploding baggie experiment is a captivating and dynamic demonstration that students should engage in with caution and under the supervision of a qualified instructor.

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7. Color Changing Chemistry Clock

This experiment not only engages students in the world of chemical kinetics but also introduces them to the concept of a chemical clock, where the color change acts as a timekeeping mechanism.

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8. Pipe Cleaner Crystal Trees

By adjusting the concentration of the Borax solution or experimenting with different pipe cleaner arrangements, students can customize their crystal trees and observe how it affects the growth patterns.

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9. How To Make Ice Sculptures

Through this experiment, students gain a deeper understanding of the physical and chemical changes that occur when water freezes and melts.

Learn more: Ice Sculpture

10. How to Make Paper

Through this hands-on activity, students gain a deeper understanding of the properties of cellulose fibers and the transformative power of chemical reactions.

Learn more: How to Make Paper

11. Color Changing Chemistry

Color changing chemistry is an enchanting experiment that offers a captivating blend of science and art. Students should embark on this colorful journey to witness the mesmerizing transformations of chemicals and explore the principles of chemical reactions.

12. Gassy Banana

The gassy banana experiment is a fun and interactive way for students to explore the principles of chemical reactions and gas production.

Learn more: Gassy Banana

13. Gingerbread Man Chemistry Experiment

This hands-on activity not only introduces students to the concepts of chemical leavening and heat-induced reactions but also allows for creativity in decorating and personalizing their gingerbread creations.

Learn more: Gingerbread Man Chemistry Experiment

14. Make Amortentia Potion

While the love potion is fictional, this activity offers a chance to explore the art of potion-making and the chemistry behind it.

Learn more: How to Make Amortentia Potion

15. Strawberry DNA Extraction

This hands-on experiment offers a unique opportunity to observe DNA, the building blocks of life, up close and learn about its structure and properties.

16. Melting Snowman

The melting snowman experiment is a fun and whimsical activity that allows students to explore the principles of heat transfer and phase changes.

Learn more: Melting Snowman

17. Acid Base Cabbage Juice

The acid-base cabbage juice experiment is an engaging and colorful activity that allows students to explore the pH scale and the properties of acids and bases.

By extracting the purple pigment from red cabbage leaves and creating cabbage juice, students can use this natural indicator to identify and differentiate between acidic and basic substances.

Learn more: Acid Base Cabbage Juice

18. Magic Milk

The magic milk experiment is a mesmerizing and educational activity that allows students to explore the concepts of surface tension and chemical reactions.

By adding drops of different food colors to a dish of milk and then introducing a small amount of dish soap, students can witness a captivating display of swirling colors and patterns.

Learn more: Magic Milk

19. Melting Ice with Salt and Water

Through this hands-on activity, students can gain a deeper understanding of the science behind de-icing and how different substances can influence the physical properties of water.

Learn more: Melting Ice with Salt and Water

20. Barking Dog Chemistry Demonstration

The barking dog chemistry demonstration is an exciting and visually captivating experiment that showcases the principles of combustion and gas production.

21. How to Make Egg Geodes

Making egg geodes is a fascinating and creative chemistry experiment that students should try. By using common materials like eggshells, salt, and food coloring, students can create their own beautiful geode-like crystals.

Learn more: How to Make Egg Geodes

22. Make Sherbet

This experiment not only engages the taste buds but also introduces concepts of acidity, solubility, and the chemical reactions that occur when the sherbet comes into contact with moisture.

Learn more: Make Sherbet

23. Hatch a Baking Soda Dinosaur Egg

As the baking soda dries and hardens around the toy, it forms a “shell” resembling a dinosaur egg. To hatch the egg, students can pour vinegar onto the shell, causing a chemical reaction that produces carbon dioxide gas.

Learn more: Steam Powered Family

24. Chromatography Flowers

By analyzing the resulting patterns, students can gain insights into the different pigments present in flowers and the science behind their colors.

Learn more: Chromatography Flowers

25. Turn Juice Into Solid

Turning juice into a solid through gelification is an engaging and educational chemistry experiment that students should try. By exploring the transformation of a liquid into a solid, students can gain insights of chemical reactions and molecular interactions.

Learn more: Turn Juice into Solid

26. Bouncy Balls

Making bouncy balls allows students to explore the fascinating properties of polymers, such as their ability to stretch and rebound.

 27. Make a Lemon Battery

Creating a lemon battery is a captivating and hands-on experiment that allows students to explore the fundamentals of electricity and chemical reactions.

28. Mentos and Soda Project

The Mentos and soda project is a thrilling and explosive experiment that students should try. By dropping Mentos candies into a bottle of carbonated soda, an exciting eruption occurs.

29. Alkali Metal in Water

The reaction of alkali metals with water is a fascinating and visually captivating chemistry demonstration.

30. Rainbow Flame

The rainbow flame experiment is a captivating and visually stunning chemistry demonstration that students should explore.

31. Sugar Yeast Experiment

This experiment not only introduces students to the concept of fermentation but also allows them to witness the effects of a living organism, yeast, on the sugar substrate.

32. The Thermite Reaction

The thermite reaction is a highly energetic and visually striking chemical reaction that students can explore with caution and under proper supervision.

This experiment showcases the principles of exothermic reactions, oxidation-reduction, and the high temperatures that can be achieved through chemical reactions.

33. Polishing Pennies

Polishing pennies is a simple and enjoyable chemistry experiment that allows students to explore the concepts of oxidation and cleaning methods.

34. Elephant Toothpaste

The elephant toothpaste experiment is a thrilling and visually captivating chemistry demonstration that students should try with caution and under the guidance of a knowledgeable instructor.

35. Magic Potion

Creating a magic potion is an exciting and imaginative activity that allows students to explore their creativity while learning about the principles of chemistry.

36. Color Changing Acid-Base Experiment

Through the color changing acid-base experiment, students can gain a deeper understanding of chemical reactions and the role of pH in our daily lives.

Learn more: Color Changing Acid-Base Experiment

37. Fill up a Balloon

Filling up a balloon is a simple and enjoyable physics experiment that demonstrates the properties of air pressure. By blowing air into a balloon, you can observe how the balloon expands and becomes inflated.

38. Jello and Vinegar

The combination of Jello and vinegar is a fascinating and tasty chemistry experiment that demonstrates the effects of acid on a gelatin-based substance.

Learn more: Jello and Vinegar

39. Vinegar and Steel Wool Reaction

This experiment not only provides a visual demonstration of the oxidation process but also introduces students to the concept of corrosion and the role of acids in accelerating the process.

Learn more: Vinegar and Steel Wool Reaction

40. Dancing Rice

The dancing rice experiment is a captivating and educational demonstration that showcases the principles of density and buoyancy.

By pouring a small amount of uncooked rice into a clear container filled with water, students can witness the rice grains moving and “dancing” in the water.

Learn more: Dancing Rice

41. Soil Testing Garden Science

Soil testing is a valuable and informative experiment that allows students to assess the composition and properties of soil.

By collecting soil samples from different locations and analyzing them, students can gain insights into the nutrient content, pH level, and texture of the soil.

Learn more: Soil Testing Garden Science

42. Heat Sensitive Color Changing Slime

Creating heat-sensitive color-changing slime is a captivating and playful chemistry experiment that students should try.

Learn more: Left Brain Craft Brain

43. Experimenting with Viscosity

Experimenting with viscosity is an engaging and hands-on activity that allows students to explore the flow properties of liquids.

Viscosity refers to a liquid’s resistance to flow, and this experiment enables students to investigate how different factors affect viscosity.

Learn more: Experimenting with Viscosity

44. Rock Candy Science

Rock candy science is a delightful and educational chemistry experiment that students should try. By growing their own rock candy crystals, students can learn about crystal formation and explore the principles of solubility and saturation.

Learn more: Rock Candy Science

45. Baking Soda vs Baking Powder

Baking soda and baking powder have distinct properties that influence the leavening process in different ways.

This hands-on experiment provides a practical understanding of how these ingredients interact with acids and moisture to create carbon dioxide gas.

46. Endothermic and Exothermic Reactions Experiment

The endothermic and exothermic reactions experiment is an exciting and informative chemistry exploration that students should try.

By observing and comparing the heat changes in different reactions, students can gain a deeper understanding of energy transfer and the concepts of endothermic and exothermic processes.

Learn more: Education.com

47. Diaper Chemistry

By dissecting a diaper and examining its components, students can uncover the chemical processes that make diapers so effective at absorbing and retaining liquids.

Learn more: Diaper Chemistry

48. Candle Chemical Reaction

The “Flame out” experiment is an intriguing and educational chemistry demonstration that students should try. By exploring the effects of a chemical reaction on a burning candle, students can witness the captivating moment when the flame is extinguished.

49. Make Curds and Whey

This experiment not only introduces students to the concept of acid-base reactions but also offers an opportunity to explore the science behind cheese-making.

Learn more: Tinkerlab

50. Grow Crystals Overnight

By creating a supersaturated solution using substances like epsom salt, sugar, or borax, students can observe the fascinating process of crystal growth. This experiment allows students to explore the principles of solubility, saturation, and nucleation.

Learn more: Grow Crystals Overnight

51. Measure Electrolytes in Sports Drinks

The “Measure Electrolytes in Sports Drinks” experiment is an informative and practical chemistry activity that students should try.

By using simple tools like a multimeter or conductivity probe, students can measure the electrical conductivity of different sports drinks to determine their electrolyte content.

52. Oxygen and Fire Experiment

The oxygen and fire experiment is a captivating and educational chemistry demonstration that students should try. By observing the effects of oxygen on a controlled fire, students can witness the essential role of oxygen in supporting combustion.

53. Electrolysis Of Water

The electrolysis of water experiment is a captivating and educational chemistry demonstration that students should try.

Learn more: Electrolysis Of Water

54. Expanding Ivory Soap

The expanding Ivory Soap experiment is a fun and interactive chemistry activity that students should try. By placing a bar of Ivory soap in a microwave, students can witness the remarkable expansion of the soap as it heats up.

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Secondary Amines Functionalized Organocatalytic Iodine Redox for High‑Performance Aqueous Dual‑Ion Batteries

• Yao, Wenjiao
• Zheng, Yongping
• Lee, Chun-Sing
• Tang, Yongbing

Aqueous dual‑ion batteries (ADIBs) based on the cooperative redox of cations and iodine anions at the anode and cathode respectively, are attracting increasing interest because of high capacity and safety. However, the full‑cell performance is limited by the sluggish iodine redox kinetics between iodide and polyiodide involving multiple electron transfer steps, and the undesirable shuttling effect of polyiodides. Here, this work reports a versatile conjugated microporous polymer functionalized with secondary amine groups as an organocatalytic cathode for ADIB, which can be positively charged and electrostatically adsorb iodide, and organocatalyze iodine redox reactions through the amine groups. Both theoretical calculations and controlled experiments confirm that the secondary amine groups confine (poly)iodide species via hydrogen bonding, which is essential for accelerating iodine redox kinetics and reducing the polyiodide shuttling effect. The ADIB achieves an ultrahigh capacity of 730 mAh g−1 with an ultrasmall overpotential of 47 mV at 1 A g−1, which also exhibits excellent rate performance and long cycling stability with a capacity retention of 74% after 5000 cycles at a high current density of 5 A g−1. This work demonstrates the promise of developing organocatalysts for accelerating electrochemical processes, which remains a virtually unexplored area in electrocatalyst design for clean energy applications.

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• Published: 12 June 2024

Experiment-free exoskeleton assistance via learning in simulation

• Shuzhen Luo 1 , 2 ,
• Menghan Jiang   ORCID: orcid.org/0009-0004-0572-059X 1 ,
• Sainan Zhang 1 ,
• Junxi Zhu   ORCID: orcid.org/0000-0001-5058-5738 1 ,
• Shuangyue Yu 1 ,
• Israel Dominguez Silva 1 ,
• Tian Wang 1 ,
• Elliott Rouse   ORCID: orcid.org/0000-0003-3880-1527 3 ,
• Bolei Zhou   ORCID: orcid.org/0000-0003-4030-0684 4 ,
• Hyunwoo Yuk   ORCID: orcid.org/0000-0003-1710-9750 5 ,
• Xianlian Zhou   ORCID: orcid.org/0000-0001-9282-5410 6 &
• Hao Su   ORCID: orcid.org/0000-0003-3299-7418 1 , 7  

Nature volume  630 ,  pages 353–359 ( 2024 ) Cite this article

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• Biomedical engineering
• Computer science
• Mechanical engineering

Exoskeletons have enormous potential to improve human locomotive performance 1 , 2 , 3 . However, their development and broad dissemination are limited by the requirement for lengthy human tests and handcrafted control laws 2 . Here we show an experiment-free method to learn a versatile control policy in simulation. Our learning-in-simulation framework leverages dynamics-aware musculoskeletal and exoskeleton models and data-driven reinforcement learning to bridge the gap between simulation and reality without human experiments. The learned controller is deployed on a custom hip exoskeleton that automatically generates assistance across different activities with reduced metabolic rates by 24.3%, 13.1% and 15.4% for walking, running and stair climbing, respectively. Our framework may offer a generalizable and scalable strategy for the rapid development and widespread adoption of a variety of assistive robots for both able-bodied and mobility-impaired individuals.

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Data availability.

All data supporting the findings of this study are available in the Article and its  Supplementary Information .   Source data are provided with this paper.

Code availability

Pseudocode for the learning-in-simulation algorithm and training process can be found in the GitHub repository https://github.com/IntelligentRobotLearning/pseudocode_learning_in_simulation .

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Acknowledgements

We thank Y. K. Chen at the Massachusetts Institute of Technology for constructive feedback and discussion of this work. This work was supported in part by the National Science Foundation (NSF) CAREER award CMMI 1944655, National Institute on Disability, Independent Living and Rehabilitation Research (NIDILRR) DRRP 90DPGE0019, Switzer Research Distinguished Fellow (SFGE22000372), NSF Future of Work 2231419 and National Institute of Health (NIH) 1R01EB035404.

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Authors and affiliations.

Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA

Shuzhen Luo, Menghan Jiang, Sainan Zhang, Junxi Zhu, Shuangyue Yu, Israel Dominguez Silva, Tian Wang & Hao Su

Department of Mechanical Engineering, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA

Shuzhen Luo

Neurobionics Lab, Department of Robotics, Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA

Elliott Rouse

Department of Computer Science, University of California, Los Angeles, CA, USA

Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea

Hyunwoo Yuk

Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA

Xianlian Zhou

Joint NCSU/UNC Department of Biomedical Engineering, North Carolina State University, Raleigh, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

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Contributions

H.S. first proposed the research idea and approach of the paper and provided the project guidance with input from E.J.R., B.Z. and X.Z. S.L., M.J. and H.S. were responsible for the design of this experiment. The methodology, code implementation and development were conducted by S.L. on the basis of a framework created by S.L. and X.Z. The mechatronics design and fabrication of the exoskeleton were done by I.D.S., M.J., S.Z. and J.Z. The experiments and data analysis were conducted by S.L., M.J., S.Z. and J.Z. The first draft of the manuscript was prepared by S.L., M.J., J.Z., S.Y., I.D.S., T.W. and H.S. Important revisions were made by S.L., J.Z., T.W., E.J.R., B.Z., H.Y., X.Z. and H.S. to the final paper. All authors contributed to the article and approved the submitted version.

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Correspondence to Hao Su .

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S.L. and H.S. are co-inventors on intellectual property related to the controller discussed in this work. H.S. is a co-founder of and has a financial interest in Picasso Intelligence, LLC. The terms of this arrangement have been reviewed and approved by NC State University in accordance with its policy on objectivity in research. The remaining authors declare no competing interests.

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Extended data figures and tables

Extended data fig. 1 overview of the learning-in-simulation control framework..

a , b , Schematic illustrations for the learning-in-simulation architecture ( a ) and the control structure for online deployment ( b ).

Extended Data Fig. 2 Motion imitation neural network for versatile activities.

Schematic illustrations for the autonomous learning framework of the reference motions (walking, running, stair climbing) from datasets based on human kinematics input and joint torque command output.

Extended Data Fig. 3 Muscle coordination neural network.

Schematic illustrations for the muscle coordination neural network based on human joint torque input and human muscle actuation output.

Extended Data Fig. 4 Exoskeleton control neural network.

Schematic illustrations for the exoskeleton control neural network based on exoskeleton state history input and joint torque command output.

Extended Data Fig. 5 Exoskeleton design.

a – c , Overall view of the whole system ( a ), actuator ( b ) and electronics ( c ).

Extended Data Fig. 6 Experiment protocol for metabolic rate and kinematic data collection during walking, running and stair climbing (also available on Protocol Exchange at: https://doi.org/10.21203/rs.3.pex-2632/v1 )

Supplementary information, supplementary information.

Supplementary Text 1–7, Methods, Figs. 1–7, Tables 1–8 and references.

Supplementary Video 1

We present a control approach that learns assistive control strategies in simulation and can be transferred to a physical wearable robot to generate continuous assistance for several locomotion activities, including walking, running and stair climbing.

Supplementary Video 2

Human response to robots is slow and controller development typically requires 24–60 min human testing and is limited to single activity (mostly walking) control only. Our method leverages dynamics-aware and data-driven simulation. It requires no human testing and can be immediately deployed to a physical exoskeleton for several activities. We only need simulation once for 8 h to learn the assistive control policy that is transferred to microcontrollers for real-time control of physical exoskeletons.

Supplementary Video 3

The learned controller in simulation is transferred to a physical exoskeleton for real-time control that immediately improves mobility. Using control policies trained in simulation, the controller is versatile to assist several locomotion modes and leads to significant metabolic expenditure savings by 24.3%, 13.1% and 15.4% during walking, running and stair climbing, respectively, compared with no exoskeleton conditions.

Supplementary Video 4

The robot learns control strategies by simultaneous training of muscle-coordination neural network and robot controller neural network. It also learns multilocomotion control by an activity imitation neural network. We bridge the sim-to-real gap by domain randomization of muscle models and robot parameters and the control policy only requires one wearable sensor per leg to control the exoskeleton.

Supplementary Video 5

The robot donning takes about 2 min and doffing takes less than 1 min. The 3.2 kg low-profile hip exoskeleton does not affect the natural range of motion and thus can assist various movements for heterogeneous able-bodied individuals.

Source data

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Luo, S., Jiang, M., Zhang, S. et al. Experiment-free exoskeleton assistance via learning in simulation. Nature 630 , 353–359 (2024). https://doi.org/10.1038/s41586-024-07382-4

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• 2.1.1: Continuous Flow Continuous Flow is a type of assay used to easily measure the progress of a reaction at discrete time points and is commonly used for determining initial rates and inhibition values.
• 2.1.2: Measuring Reaction Rates The method for determining a reaction rate is relatively straightforward. Since a reaction rate is based on change over time, it must be determined from tabulated values or found experimentally. With the obtained data, it is possible to calculate the reaction rate either algebraically or graphically. What follows is general guidance and examples of measuring the rates of a reaction.
• 2.1.3: Rate vs. Concentration Proportionalities
• 2.1.4.1: Flash Photolysis
• 2.1.4.2: Pressure Jump
• 2.1.5: Spectrophotometry Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through sample solution. The basic principle is that each compound absorbs or transmits light over a certain range of wavelength. This measurement can also be used to measure the amount of a known chemical substance.
• 2.1.6: Stopped Flow The stopped-flow technique allows for the evaluation of solution-based kinetics on a milliseconds timescale with a very small volume of reactants used.

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Combined effect of pressure and temperature on nitrogen reduction reaction in water.

1. Introduction

2. materials and methods, 2.1. electrodes, 2.2. pressurized electrochemical h-cell, 2.3. electrochemical ammonia synthesis, 2.4. ammonia detection, 3. results and discussion, 4. conclusions, supplementary materials, author contributions, data availability statement, conflicts of interest.

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Tranchida, G.; Milazzo, R.G.; Lombardo, S.A.; Privitera, S.M.S. Combined Effect of Pressure and Temperature on Nitrogen Reduction Reaction in Water. Energies 2024 , 17 , 2963. https://doi.org/10.3390/en17122963

Tranchida G, Milazzo RG, Lombardo SA, Privitera SMS. Combined Effect of Pressure and Temperature on Nitrogen Reduction Reaction in Water. Energies . 2024; 17(12):2963. https://doi.org/10.3390/en17122963

Tranchida, Giuseppe, Rachela G. Milazzo, Salvatore A. Lombardo, and Stefania M. S. Privitera. 2024. "Combined Effect of Pressure and Temperature on Nitrogen Reduction Reaction in Water" Energies 17, no. 12: 2963. https://doi.org/10.3390/en17122963

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