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  1. Article ; Online: An Assessment of Sikh Turban's Head Protection in Bicycle Incident Scenarios.

    Yu, Xiancheng / Singh, Gurpreet / Kaur, Amritvir / Ghajari, Mazdak

    Annals of biomedical engineering

    2024  Volume 52, Issue 4, Page(s) 946–957

    Abstract: Due to religious tenets, Sikh population wear turbans and are exempted from wearing helmets in several countries. However, the extent of protection provided by turbans against head injuries during head impacts remains untested. One aim of this study was ... ...

    Abstract Due to religious tenets, Sikh population wear turbans and are exempted from wearing helmets in several countries. However, the extent of protection provided by turbans against head injuries during head impacts remains untested. One aim of this study was to provide the first-series data of turbans' protective performance under impact conditions that are representative of real-world bicycle incidents and compare it with the performance of bicycle helmets. Another aim was to suggest potential ways for improving turban's protective performance. We tested five different turbans, distinguished by two wrapping styles and two fabric materials with a size variation in one of the styles. A Hybrid III headform fitted with the turban was dropped onto a 45 degrees anvil at 6.3 m/s and head accelerations were measured. We found large difference in the performance of different turbans, with up to 59% difference in peak translational acceleration, 85% in peak rotational acceleration, and 45% in peak rotational velocity between the best and worst performing turbans. For the same turban, impact on the left and right sides of the head produced very different head kinematics, showing the effects of turban layering. Compared to unprotected head impacts, turbans considerably reduce head injury metrics. However, turbans produced higher values of peak linear and rotational accelerations in front and left impacts than bicycle helmets, except from one turban which produced lower peak head kinematics values in left impacts. In addition, turbans produced peak rotational velocities comparable with bicycle helmets, except from one turban which produced higher values. The impact locations tested here were covered with thick layers of turbans and they were impacted against flat anvils. Turbans may not provide much protection if impacts occur at regions covered with limited amount of fabric or if the impact is against non-flat anvils, which remain untested. Our analysis shows that turbans can be easily compressed and bottom out creating spikes in the headform's translational acceleration. In addition, the high friction between the turban and anvil surface leads to higher tangential force generating more rotational motion. Hence, in addition to improving the coverage of the head, particularly in the crown and rear locations, we propose two directions for turban improvement: (i) adding deformable materials within the turban layers to increase the impact duration and reduce the risk of bottoming out; (ii) reducing the friction between turban layers to reduce the transmission of rotational motion to the head. Overall, the study assessed Turbans' protection in cyclist head collisions, with a vision that the results of this study can guide further necessary improvements for advanced head protection for the Sikh community.
    MeSH term(s) Humans ; Bicycling/injuries ; Craniocerebral Trauma/prevention & control ; Mechanical Phenomena ; Biomechanical Phenomena ; Acceleration ; Head Protective Devices ; Head
    Language English
    Publishing date 2024-02-02
    Publishing country United States
    Document type Journal Article
    ZDB-ID 185984-5
    ISSN 1573-9686 ; 0191-5649 ; 0090-6964
    ISSN (online) 1573-9686
    ISSN 0191-5649 ; 0090-6964
    DOI 10.1007/s10439-023-03431-7
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  2. Article ; Online: Protective Performance of Helmets and Goggles in Mitigating Brain Biomechanical Response to Primary Blast Exposure.

    Yu, Xiancheng / Ghajari, Mazdak

    Annals of biomedical engineering

    2022  Volume 50, Issue 11, Page(s) 1579–1595

    Abstract: The current combat helmets are primarily designed to mitigate blunt impacts and ballistic loadings. Their protection against primary blast wave is not well studied. In this paper, we comprehensively assessed the protective capabilities of the advanced ... ...

    Abstract The current combat helmets are primarily designed to mitigate blunt impacts and ballistic loadings. Their protection against primary blast wave is not well studied. In this paper, we comprehensively assessed the protective capabilities of the advanced combat helmet and goggles against blast waves with different intensity and directions. Using a high-fidelity human head model, we compared the intracranial pressure (ICP), cerebrospinal fluid (CSF) cavitation, and brain strain and strain rate predicted from bare head, helmet-head and helmet-goggles-head simulations. The helmet was found to be effective in mitigating the positive ICP (24-57%) and strain rate (5-34%) in all blast scenarios. Goggles were found to be effective in mitigating the positive ICP in frontal (6-16%) and lateral (5-7%) blast exposures. However, the helmet and goggles had minimal effects on mitigating CSF cavitation and even increased brain strain. Further investigation showed that wearing a helmet leads to higher risk of cavitation. In addition, their presence increased the head kinetic energy, leading to larger strains in the brain. Our findings can improve our understanding of the protective effects of helmets and goggles and guide the design of helmet pads to mitigate brain responses to blast.
    MeSH term(s) Humans ; Head Protective Devices ; Eye Protective Devices ; Blast Injuries/prevention & control ; Computer Simulation ; Biomechanical Phenomena ; Brain/physiology
    Language English
    Publishing date 2022-03-16
    Publishing country United States
    Document type Journal Article
    ZDB-ID 185984-5
    ISSN 1573-9686 ; 0191-5649 ; 0090-6964
    ISSN (online) 1573-9686
    ISSN 0191-5649 ; 0090-6964
    DOI 10.1007/s10439-022-02936-x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Head Impact Location, Speed and Angle from Falls and Trips in the Workplace.

    Yu, Xiancheng / Baker, Claire E / Ghajari, Mazdak

    Annals of biomedical engineering

    2023  

    Abstract: Traumatic brain injury (TBI) is a common injury in the workplace. Trips and falls are the leading causes of TBI in the workplace. However, industrial safety helmets are not designed for protecting the head under these impact conditions. Instead, they are ...

    Abstract Traumatic brain injury (TBI) is a common injury in the workplace. Trips and falls are the leading causes of TBI in the workplace. However, industrial safety helmets are not designed for protecting the head under these impact conditions. Instead, they are designed to pass the regulatory standards which test head protection against falling heavy and sharp objects. This is likely to be due to the limited understanding of head impact conditions from trips and falls in workplace. In this study, we used validated human multi-body models to predict the head impact location, speed and angle (measured from the ground) during trips, forward falls and backward falls. We studied the effects of worker size, initial posture, walking speed, width and height of the tripping barrier, bracing and falling height on the head impact conditions. Overall, we performed 1692 simulations. The head impact speed was over two folds larger in falls than trips, with backward falls producing highest impact speeds. However, the trips produced impacts with smaller impact angles to the ground. Increasing the walking speed increased the head impact speed but bracing reduced it. We found that 41% of backward falls and 19% of trips/forward falls produced head impacts located outside the region of helmet coverage. Next, we grouped all the data into three sub-groups based on the head impact angle: [0°, 30°], (30°, 60°] and (60°, 90°] and excluded groups with small number of cases. We found that most trips and forward falls lead to impact angles within the (30°, 60°] and (60°, 90°] groups while all backward falls produced impact angles within (60°, 90°] group. We therefore determined five representative head impact conditions from these groups by selecting the 75th percentile speed, mean value of angle intervals and median impact location (determined by elevation and azimuth angles) of each group. This led to two representative head impact conditions for trips: 2.7 m/s at 45° and 3.9 m/s at 75°, two for forward falls: 3.8 m/s at 45° and 5.5 m/s at 75° and one for backward falls: 9.4 m/s at 75°. These impact conditions can be used to improve industrial helmet standards.
    Language English
    Publishing date 2023-02-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 185984-5
    ISSN 1573-9686 ; 0191-5649 ; 0090-6964
    ISSN (online) 1573-9686
    ISSN 0191-5649 ; 0090-6964
    DOI 10.1007/s10439-023-03146-9
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Micromechanics in biology and medicine.

    MacManus, David B / Khorshidi, Majid Akbarzadeh / Ghajari, Mazdak / Sedighi, Hamid M

    IET nanobiotechnology

    2023  Volume 17, Issue 3, Page(s) 125–126

    MeSH term(s) Biology ; Microtechnology ; Medicine
    Language English
    Publishing date 2023-04-19
    Publishing country United States
    Document type Editorial ; Introductory Journal Article
    ZDB-ID 2264529-9
    ISSN 1751-875X ; 1751-875X
    ISSN (online) 1751-875X
    ISSN 1751-875X
    DOI 10.1049/nbt2.12130
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: In-Depth Bicycle Collision Reconstruction: From a Crash Helmet to Brain Injury Evaluation.

    Yu, Xiancheng / Baker, Claire E / Brown, Mike / Ghajari, Mazdak

    Bioengineering (Basel, Switzerland)

    2023  Volume 10, Issue 3

    Abstract: Traumatic brain injury (TBI) is a prevalent injury among cyclists experiencing head collisions. In legal cases, reliable brain injury evaluation can be difficult and controversial as mild injuries cannot be diagnosed with conventional brain imaging ... ...

    Abstract Traumatic brain injury (TBI) is a prevalent injury among cyclists experiencing head collisions. In legal cases, reliable brain injury evaluation can be difficult and controversial as mild injuries cannot be diagnosed with conventional brain imaging methods. In such cases, accident reconstruction may be used to predict the risk of TBI. However, lack of collision details can render accident reconstruction nearly impossible. Here, we introduce a reconstruction method to evaluate the brain injury in a bicycle-vehicle collision using the crash helmet alone. Following a thorough inspection of the cyclist's helmet, we identified a severe impact, a moderate impact and several scrapes, which helped us to determine the impact conditions. We used our helmet test rig and intact helmets identical to the cyclist's helmet to replicate the damage seen on the cyclist's helmet involved in the real-world collision. We performed both linear and oblique impacts, measured the translational and rotational kinematics of the head and predicted the strain and the strain rate across the brain using a computational head model. Our results proved the hypothesis that the cyclist sustained a severe impact followed by a moderate impact on the road surface. The estimated head accelerations and velocity (167 g, 40.7 rad/s and 13.2 krad/s
    Language English
    Publishing date 2023-03-02
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2746191-9
    ISSN 2306-5354
    ISSN 2306-5354
    DOI 10.3390/bioengineering10030317
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: A Review of Cyclist Head Injury, Impact Characteristics and the Implications for Helmet Assessment Methods.

    Baker, Claire E / Yu, Xiancheng / Patel, Saian / Ghajari, Mazdak

    Annals of biomedical engineering

    2023  Volume 51, Issue 5, Page(s) 875–904

    Abstract: Head injuries are common for cyclists involved in collisions. Such collision scenarios result in a range of injuries, with different head impact speeds, angles, locations, or surfaces. A clear understanding of these collision characteristics is vital to ... ...

    Abstract Head injuries are common for cyclists involved in collisions. Such collision scenarios result in a range of injuries, with different head impact speeds, angles, locations, or surfaces. A clear understanding of these collision characteristics is vital to design high fidelity test methods for evaluating the performance of helmets. We review literature detailing real-world cyclist collision scenarios and report on these key characteristics. Our review shows that helmeted cyclists have a considerable reduction in skull fracture and focal brain pathologies compared to non-helmeted cyclists, as well as a reduction in all brain pathologies. The considerable reduction in focal head pathologies is likely to be due to helmet standards mandating thresholds of linear acceleration. The less considerable reduction in diffuse brain injuries is likely to be due to the lack of monitoring head rotation in test methods. We performed a novel meta-analysis of the location of 1809 head impacts from ten studies. Most studies showed that the side and front regions are frequently impacted, with one large, contemporary study highlighting a high proportion of occipital impacts. Helmets frequently had impact locations low down near the rim line. The face is not well protected by most conventional bicycle helmets. Several papers determine head impact speed and angle from in-depth reconstructions and computer simulations. They report head impact speeds from 5 to 16 m/s, with a concentration around 5 to 8 m/s and higher speeds when there was another vehicle involved in the collision. Reported angles range from 10° to 80° to the normal, and are concentrated around 30°-50°. Our review also shows that in nearly 80% of the cases, the head impact is reported to be against a flat surface. This review highlights current gaps in data, and calls for more research and data to better inform improvements in testing methods of standards and rating schemes and raise helmet safety.
    MeSH term(s) Humans ; Bicycling/injuries ; Craniocerebral Trauma/prevention & control ; Computer Simulation ; Head Protective Devices ; Acceleration ; Accidents, Traffic
    Language English
    Publishing date 2023-03-14
    Publishing country United States
    Document type Meta-Analysis ; Journal Article ; Review
    ZDB-ID 185984-5
    ISSN 1573-9686 ; 0191-5649 ; 0090-6964
    ISSN (online) 1573-9686
    ISSN 0191-5649 ; 0090-6964
    DOI 10.1007/s10439-023-03148-7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Oblique impact responses of Hybrid III and a new headform with more biofidelic coefficient of friction and moments of inertia.

    Yu, Xiancheng / Halldin, Peter / Ghajari, Mazdak

    Frontiers in bioengineering and biotechnology

    2022  Volume 10, Page(s) 860435

    Abstract: New oblique impact methods for evaluating head injury mitigation effects of helmets are emerging, which mandate measuring both translational and rotational kinematics of the headform. These methods need headforms with biofidelic mass, moments of inertia ( ...

    Abstract New oblique impact methods for evaluating head injury mitigation effects of helmets are emerging, which mandate measuring both translational and rotational kinematics of the headform. These methods need headforms with biofidelic mass, moments of inertia (MoIs), and coefficient of friction (CoF). To fulfill this need, working group 11 of the European standardization head protection committee (CEN/TC158) has been working on the development of a new headform with realistic MoIs and CoF, based on recent biomechanics research on the human head. In this study, we used a version of this headform (Cellbond) to test a motorcycle helmet under the oblique impact at 8 m/s at five different locations. We also used the Hybrid III headform, which is commonly used in the helmet oblique impact. We tested whether there is a difference between the predictions of the headforms in terms of injury metrics based on head kinematics, including peak translational and rotational acceleration, peak rotational velocity, and BrIC (brain injury criterion). We also used the Imperial College finite element model of the human head to predict the strain and strain rate across the brain and tested whether there is a difference between the headforms in terms of the predicted strain and strain rate. We found that the Cellbond headform produced similar or higher peak translational accelerations depending on the impact location (-3.2% in the front-side impact to 24.3% in the rear impact). The Cellbond headform, however, produced significantly lower peak rotational acceleration (-41.8% in a rear impact to -62.7% in a side impact), peak rotational velocity (-29.5% in a side impact to -47.6% in a rear impact), and BrIC (-29% in a rear-side impact to -45.3% in a rear impact). The 90th percentile values of the maximum brain strain and strain rate were also significantly lower using this headform. Our results suggest that MoIs and CoF have significant effects on headform rotational kinematics, and consequently brain deformation, during the helmeted oblique impact. Future helmet standards and rating methods should use headforms with realistic MoIs and CoF (e.g., the Cellbond headform) to ensure more accurate representation of the head in laboratory impact tests.
    Language English
    Publishing date 2022-09-08
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2719493-0
    ISSN 2296-4185
    ISSN 2296-4185
    DOI 10.3389/fbioe.2022.860435
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Computational prediction of head-ground impact kinematics in e-scooter falls.

    Posirisuk, Pasinee / Baker, Claire / Ghajari, Mazdak

    Accident; analysis and prevention

    2022  Volume 167, Page(s) 106567

    Abstract: E-scooters are the fastest growing mode of micro-mobility with important environmental benefits. However, there are serious concerns about injuries caused by e-scooter accidents. Falls due to poor road surface conditions are a common cause of injury in e- ...

    Abstract E-scooters are the fastest growing mode of micro-mobility with important environmental benefits. However, there are serious concerns about injuries caused by e-scooter accidents. Falls due to poor road surface conditions are a common cause of injury in e-scooter riders, and head injuries are one of the most common and concerning injuries in e-scooter falls. However, the head-ground impact biomechanics in e-scooter falls and its relationship with e-scooter speed and design, road surface conditions and wearing helmets remain poorly understood. To address some of these key questions, we predicted the head-ground impact force and velocity of e-scooter riders in different falls caused by potholes. We used multi-body dynamics approach to model a commercially available e-scooter and simulate 180 falls using human body models. We modelled different pothole sizes to test whether the pothole width and depth influences the onset of falls and head-ground impact velocity and force. We also tested whether the e-scooter travelling speed has an influence on the head-ground impact velocity and force. The simulations were carried out with three human body models to ensure that the results of the study are inclusive of a wide range of rider sizes. For our 10 in. diameter e-scooter wheels, we found a sudden increase in the occurrence of falls when the pothole depth was increased from 3 cm (no falls) to 6 cm (41 falls out of 60 cases). When the falls occurred, we found a head-ground impact force of 13.2 ± 3.4kN, which is larger than skull fracture thresholds. The head-ground impact speed was 6.3 ± 1.4 m/s, which is the same as the impact speed prescribed in bicycle helmet standards. All e-scooter falls resulted in oblique head impacts, with an impact angle of 65 ± 10° (measured from the ground). Decreasing the e-scooter speed reduced the head impact speed. For instance, reducing the e-scooter speed from 30 km/h to 20 km/h led to a 14% reduction in the mean impact speed and 12% reduction in the mean impact force, as predicted by the models. The models also showed that the median male riders were sustaining higher head-ground impact force and speed compared with the small female and large male riders. The findings of this study can assist authorities and e-scooter hiring companies to take more informed actions about road surface conditions and speed limits. These results can also help define representative impact test conditions for assessing the performance of helmets used by e-scooter riders in order to reduce head and brain injuries in e-scooter falls.
    MeSH term(s) Accidental Falls ; Accidents, Traffic ; Biomechanical Phenomena ; Craniocerebral Trauma/prevention & control ; Female ; Head Protective Devices ; Humans ; Male
    Language English
    Publishing date 2022-01-13
    Publishing country England
    Document type Journal Article
    ZDB-ID 210223-7
    ISSN 1879-2057 ; 0001-4575
    ISSN (online) 1879-2057
    ISSN 0001-4575
    DOI 10.1016/j.aap.2022.106567
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  9. Article ; Online: In-Depth Bicycle Collision Reconstruction

    Xiancheng Yu / Claire E. Baker / Mike Brown / Mazdak Ghajari

    Bioengineering, Vol 10, Iss 317, p

    From a Crash Helmet to Brain Injury Evaluation

    2023  Volume 317

    Abstract: Traumatic brain injury (TBI) is a prevalent injury among cyclists experiencing head collisions. In legal cases, reliable brain injury evaluation can be difficult and controversial as mild injuries cannot be diagnosed with conventional brain imaging ... ...

    Abstract Traumatic brain injury (TBI) is a prevalent injury among cyclists experiencing head collisions. In legal cases, reliable brain injury evaluation can be difficult and controversial as mild injuries cannot be diagnosed with conventional brain imaging methods. In such cases, accident reconstruction may be used to predict the risk of TBI. However, lack of collision details can render accident reconstruction nearly impossible. Here, we introduce a reconstruction method to evaluate the brain injury in a bicycle–vehicle collision using the crash helmet alone. Following a thorough inspection of the cyclist’s helmet, we identified a severe impact, a moderate impact and several scrapes, which helped us to determine the impact conditions. We used our helmet test rig and intact helmets identical to the cyclist’s helmet to replicate the damage seen on the cyclist’s helmet involved in the real-world collision. We performed both linear and oblique impacts, measured the translational and rotational kinematics of the head and predicted the strain and the strain rate across the brain using a computational head model. Our results proved the hypothesis that the cyclist sustained a severe impact followed by a moderate impact on the road surface. The estimated head accelerations and velocity (167 g, 40.7 rad/s and 13.2 krad/s 2 ) and the brain strain and strain rate (0.541 and 415/s) confirmed that the severe impact was large enough to produce mild to moderate TBI. The method introduced in this study can guide future accident reconstructions, allowing for the evaluation of TBI using the crash helmet only.
    Keywords biomechanics ; traumatic brain injury ; road traffic accident ; accident reconstruction ; simulation ; impact test ; Technology ; T ; Biology (General) ; QH301-705.5
    Subject code 306
    Language English
    Publishing date 2023-03-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article: Non-Lethal Blasts can Generate Cavitation in Cerebrospinal Fluid While Severe Helmeted Impacts Cannot: A Novel Mechanism for Blast Brain Injury.

    Yu, Xiancheng / Nguyen, Thuy-Tien / Wu, Tianchi / Ghajari, Mazdak

    Frontiers in bioengineering and biotechnology

    2022  Volume 10, Page(s) 808113

    Abstract: Cerebrospinal fluid (CSF) cavitation is a likely physical mechanism for producing traumatic brain injury (TBI) under mechanical loading. In this study, we investigated CSF cavitation under blasts and helmeted impacts which represented loadings in ... ...

    Abstract Cerebrospinal fluid (CSF) cavitation is a likely physical mechanism for producing traumatic brain injury (TBI) under mechanical loading. In this study, we investigated CSF cavitation under blasts and helmeted impacts which represented loadings in battlefield and road traffic/sports collisions. We first predicted the human head response under the blasts and impacts using computational modelling and found that the blasts can produce much lower negative pressure at the contrecoup CSF region than the impacts. Further analysis showed that the pressure waves transmitting through the skull and soft tissue are responsible for producing the negative pressure at the contrecoup region. Based on this mechanism, we hypothesised that blast, and not impact, can produce CSF cavitation. To test this hypothesis, we developed a one-dimensional simplified surrogate model of the head and exposed it to both blasts and impacts. The test results confirmed the hypothesis and computational modelling of the tests validated the proposed mechanism. These findings have important implications for prevention and diagnosis of blast TBI.
    Language English
    Publishing date 2022-07-07
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2719493-0
    ISSN 2296-4185
    ISSN 2296-4185
    DOI 10.3389/fbioe.2022.808113
    Database MEDical Literature Analysis and Retrieval System OnLINE

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