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741 results on '"Voloshina, Alexandra"'

6. Factors controlling the organ-specific T1 contrast effect of silica nanoparticles co-doped with both Mn2+ ions and oleate-coated iron oxides

Author

Bochkova, Olga, Stepanov, Alexey, Bebyakina, Anastasiya, Smekalov, Daniil, Kholin, Kirill, Nizameev, Irek, Romashchenko, Alexander, Zavjalov, Evgenii, Lubina, Anna, Voloshina, Alexandra, Tyapkina, Oksana, Tarasov, Maxim, Sultanov, Timur, Rümmeli, Mark, Salnikov, Vadim, Budnikova, Yulia, and Mustafina, Asiya

Published
2024
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22. Optimized hip–knee–ankle exoskeleton assistance at a range of walking speeds

Author

Bryan, Gwendolyn M, Franks, Patrick W, Song, Seungmoon, Voloshina, Alexandra S, Reyes, Ricardo, O’Donovan, Meghan P, Gregorczyk, Karen N, and Collins, Steven H

Subjects
Clinical Research, Musculoskeletal, Ankle, Ankle Joint, Biomechanical Phenomena, Exoskeleton Device, Gait, Humans, Walking, Walking Speed, Exoskeleton, Augmentation, Walking speed, Human-in-the-loop optimization, Biomedical Engineering, Neurosciences, Rehabilitation
Abstract

BackgroundAutonomous exoskeletons will need to be useful at a variety of walking speeds, but it is unclear how optimal hip-knee-ankle exoskeleton assistance should change with speed. Biological joint moments tend to increase with speed, and in some cases, optimized ankle exoskeleton torques follow a similar trend. Ideal hip-knee-ankle exoskeleton torque may also increase with speed. The purpose of this study was to characterize the relationship between walking speed, optimal hip-knee-ankle exoskeleton assistance, and the benefits to metabolic energy cost.MethodsWe optimized hip-knee-ankle exoskeleton assistance to reduce metabolic cost for three able-bodied participants walking at 1.0 m/s, 1.25 m/s and 1.5 m/s. We measured metabolic cost, muscle activity, exoskeleton assistance and kinematics. We performed Friedman's tests to analyze trends across walking speeds and paired t-tests to determine if changes from the unassisted conditions to the assisted conditions were significant.ResultsExoskeleton assistance reduced the metabolic cost of walking compared to wearing the exoskeleton with no torque applied by 26%, 47% and 50% at 1.0, 1.25 and 1.5 m/s, respectively. For all three participants, optimized exoskeleton ankle torque was the smallest for slow walking, while hip and knee torque changed slightly with speed in ways that varied across participants. Total applied positive power increased with speed for all three participants, largely due to increased joint velocities, which consistently increased with speed.ConclusionsExoskeleton assistance is effective at a range of speeds and is most effective at medium and fast walking speeds. Exoskeleton assistance was less effective for slow walking, which may explain the limited success in reducing metabolic cost for patient populations through exoskeleton assistance. Exoskeleton designers may have more success when targeting activities and groups with faster walking speeds. Speed-related changes in optimized exoskeleton assistance varied by participant, indicating either the benefit of participant-specific tuning or that a wide variety of torque profiles are similarly effective.

Published
2021

27. Synthesis, antiviral evaluation, molecular docking study and cytotoxicity of 5′-phosphorylated 1,2,3-triazolyl nucleoside analogues with thymine and 6-methyl uracil moieties

Author

Garifullin, Bulat F., Tatarinov, Dmitry A., Andreeva, Olga V., Belenok, Mayya G., Strobykina, Irina Yu., Khabibulina, Leysan R., Shepelina, Anna V., Zarubaev, Vladimir V., Slita, Alexander V., Volobueva, Alexandrina S., Voloshina, Alexandra D., Lyubina, Anna P., Saifina, Liliya E., Semenov, Vyacheslav E., and Kataev, Vladimir E.

Published
2023
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28. ROS-producing nanomaterial engineered from Cu(I) complexes with P2N2-ligands for cancer cells treating

Author

Faizullin, Bulat A., Dayanova, Irina R., Kurenkov, Alexey V., Gubaidullin, Aidar T., Saifina, Alina F., Nizameev, Irek R., Kholin, Kirill V., Khrizanforov, Mikhail N., Sirazieva, Aisylu R., Litvinov, Igor A., Voloshina, Alexandra D., Lyubina, Anna P., Sibgatullina, Guzel V., Samigullin, Dmitry V., Musina, Elvira I., Strelnik, Igor D., Karasik, Andrey A., and Mustafina, Asiya R.

Published
2023
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30. Dark cytotoxicity beyond photo-induced one of silica nanoparticles incorporated with RuII nitrosyl complexes and luminescent {Mo6I8} cluster units

Author

Bochkova, Olga, Fedorenko, Svetlana, Mikhailov, Artem, Kostin, Gennadiy, Mikhailov, Maxim, Sokolov, Maxim, Elistratova, Julia, Kholin, Kirill, Tarasov, Maxim, Budnikova, Yulia, Sibgatullina, Guzel, Samigullin, Dmitry, Nizameev, Irek, Salnikov, Vadim, Yakovlev, Ivan, Rozhentsova, Darina, Lyubina, Anna, Amerhanova, Syumbelya, Voloshina, Alexandra, Gerasimova, Tatiana, and Mustafina, Asiya

Published
2024
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34. Shortcomings of human-in-the-loop optimization of an ankle-foot prosthesis emulator: a case series

Author

Welker, Cara Gonzalez, Voloshina, Alexandra S, Chiu, Vincent L, and Collins, Steven H

Subjects
Bioengineering, Clinical Research, Physical Rehabilitation, Assistive Technology, Rehabilitation, Affordable and Clean Energy, prosthesis, optimization, amputation
Abstract

Human-in-the-loop optimization allows for individualized device control based on measured human performance. This technique has been used to produce large reductions in energy expenditure during walking with exoskeletons but has not yet been applied to prosthetic devices. In this series of case studies, we applied human-in-the-loop optimization to the control of an active ankle-foot prosthesis used by participants with unilateral transtibial amputation. We optimized the parameters of five control architectures that captured aspects of successful exoskeletons and commercial prostheses, but none resulted in significantly lower metabolic rate than generic control. In one control architecture, we increased the exposure time per condition by a factor of five, but the optimized controller still resulted in higher metabolic rate. Finally, we optimized for self-reported comfort instead of metabolic rate, but the resulting controller was not preferred. There are several reasons why human-in-the-loop optimization may have failed for people with amputation. Control architecture is an unlikely cause given the variety of controllers tested. The lack of effect likely relates to changes in motor adaptation, learning, or objectives in people with amputation. Future work should investigate these potential causes to determine whether human-in-the-loop optimization for prostheses could be successful.

Published
2021

36. The effects of ground-irregularity-cancelling prosthesis control on balance over uneven surfaces

Author

Chiu, Vincent L, Voloshina, Alexandra S, and Collins, Steven H

Subjects
Allied Health and Rehabilitation Science, Engineering, Health Sciences, Sports Science and Exercise, Clinical Research, ankle-foot prosthesis, uneven terrain, balance, transtibial amputation
Abstract

Over half of individuals with a lower-limb amputation are unable to walk on uneven terrain. Using a prosthesis emulator system, we developed an irregularity-cancelling controller intended to reduce the effect of disturbances resulting from uneven surfaces. This controller functions by changing the neutral angles of two forefoot digits in response to local terrain heights. To isolate the effects of the controller, we also programmed a spring-like controller that maintained fixed neutral angles. Five participants with transtibial amputation walked on a treadmill with an uneven walking surface. Compared with the spring-like controller, the irregularity-cancelling controller reduced ankle torque variability by 41% in the sagittal plane and 64% in the frontal plane. However, user outcomes associated with balance were mostly unaffected; only trunk movement variability was reduced, whereas metabolic rate, mediolateral centre of mass motion, and variabilities in step width, step length and step time were unchanged. We conclude that reducing ankle torque variability of the affected limb is not sufficient for reducing the overall effect of disturbances due to uneven terrain. It is possible that other factors, such as changes in step height or disturbances to the intact limb, play a larger role in difficulty balancing while walking over uneven surfaces.

Published
2021

47. Tricks for organic-capped Cu2-xS nanoparticles encapsulation into silica nanocomposites co-doped with red emitting luminophore for NIR activated-photothermal/chemodynamic therapy

Author

Fedorenko, Svetlana, Farvaeva, Dinara, Stepanov, Alexey, Bochkova, Olga, Kholin, Kirill, Nizameev, Irek, Drobyshev, Sergey, Gerasimova, Tatiana, Voloshina, Alexandra, Fanizza, Elizabetta, Depalo, Nicoletta, Sibgatullina, Guzel, Samigullin, Dmitry, Petrov, Konstantin, Gubaidullin, Aidar, and Mustafina, Asiya

Published
2022
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