Free-fall Impact Research Articles

Comparative Characteristics of Structural and Functional Changes in the Hippocampal CA<sub>3</sub> Region in White Rats After Acute Ischemia and Brain Injury

The aimof the study was to study pyramidal neurons and astrocytes of the hippocampal CA3region in dynamics in white rats after acute ischemia and severe traumatic brain injury.Material and methods.Acute ischemia was simulated by 20-minute occlusion of the common carotid arteries (CCA), and severe traumatic brain injury (TBI) by a free-falling weight impact. The Nissl staining, hematoxylin and eosin staining, immunohistochemical reactions for NSE, MAP-2, p38, GFAP were used in the study. The proliferative activity of the cells was assessed using the Ki-67 response. The study was carried out on thin (4 μm) serial frontal sections in the animals of the control group (animals without pathological factors, n=5) in 1, 3, 7 and 14 days after the experimental modeling of CCA occlusion (n=20) and TBI (n=20). Morphometric analysis was performed using the ImageJ 1.52s software. The relative area of edema-swelling zones in the neuropil, the number density of pyramidal neurons, the content of dystrophic and necrobiotically altered neurons, the content of neurons with one or more nucleoli, proliferating cells, the density of large trunks of pyramidal neurons dendrites, the total number density and the relative area of giant synaptic terminals in stratum lucidum was detected. The distribution of variation series, the verification of statistical hypotheses, and the construction of graphs were assessed using the Statistica 8.0 software and the R.Results.Mortality between groups did not differ and did not exceed 7%. In a day after CCA occlusion and TBI, there was a statistically significant increase in the relative volume of edema-swelling, the content of dystrophic and necrobiotically altered neurons, the total number density and the relative area of the terminals decreased, but the total number density of neurons did not change. In 3, 7 and 14 days, the mechanisms of neuroglio- and synaptic plasticity were activated. The content of neurons with two or more nucleoli increased, the total number and content of hypertrophied astrocytes increased, the cytoskeleton of damaged neurons was restored, and the content of interneuronal synapses increased. During the period from 3 to 14 days, the total number density of neurons in CCA occlusion decreased by 16.3%, and in TBI – by 33.7% (p=0.001). Pathological and compensatory-restorative changes were of a diffuse-focal nature and were more pronounced after TBI.Conclusion.Thus, the same type of focal heterochronous and heteromorphic dystrophic, necrobiotic and compensatory-restorative changes in the nervous tissue were observed after CCA occlusion and TBI in the hippocampal CA3region. Structural and functional recovery occurred together with a decrease in the total numerical density of pyramidal neurons and edema-swelling of the nervous tissue. More pronounced dystrophic and necrobiotic changes in TBI were combined with more pronounced compensatory-restorative changes in astrocytes and giant interneuronal synapses of the hippocampal CA3region. The revealed changes were considered as the basis for the standard permanent compensatory-restorative reorganization of the nervous tissue of the hippocampus in the postischemic and post-traumatic periods.

Effects of Recombinant Human Erythropoietin on Inflammatory Factors in Rats with Traumatic Brain Injury

To study the effects of recombinant human erythropoietin on inflammatory factors in rats with traumatic brain injury is the main objective. A total of 45 specific-pathogen-free grade male Sprague-Dawley rats were randomly assigned into sham operation group (sham group), model group and recombinant human erythropoietin intervention group (treatment group) (n=15). Model and treatment groups were prepared into traumatic brain injury model by hitting the head through the modified Feeney’s free-fall impact method, while the head of sham group was not hit. After modeling, treatment group was intraperitoneally injected with recombinant human erythropoietin at 5000 IU/kg daily and sham and model groups were intraperitoneally injected with the same dose of normal saline. The rats were killed after 7 d of continuous administration. The changes of brain mitochondrial membrane potential were detected through rhodamine 123 staining and immunocytochemistry and Western blotting were separately employed to measure the expressions of interleukin-1β, interleukin-6 and tumor necrosis factor-α in brain tissues and the expression levels of dynamin-related protein 1, fission 1, mitofusin 2 and optic atrophy 1, mitochondrial dynamics related proteins in brain tissues. Compared with sham group, model group exhibited significantly weakened rhodamine 123 fluorescence intensity, increased expressions of interleukin-1β, interleukin-6 and tumor necrosis factor-α, dynamin-related protein 1 and fission 1 and reduced expressions of mitofusin 2 and optic atrophy 1 in brain tissues (p<0.05). In comparison with model group, treatment group had significantly enhanced rhodamine 123 fluorescence intensity, reduced expressions of interleukin-1β, interleukin-6 and tumor necrosis factor-α, dynamin-related protein 1 and fission 1 and elevated expressions of mitofusin 2 and optic atrophy 1 in brain tissues (p<0.05). Recombinant human erythropoietin can protect the brain after traumatic brain injury by relieving the inflammatory response and mitochondrial injury after traumatic brain injury.

Effect of electroacupuncture at different stages on the expression of Fas and FasL in brain tissue of rats with traumatic brain injury

To investigate the expression of apoptosis-related proteins Fas and FasL in the brain tissue of rats with traumatic brain injury and the effect of electroacupuncture on the expression of Fas and FasL, so as to explore the effective time window of electroacupuncture in the treatment of traumatic brain injury. Sprague-Dawley rats were randomly divided into blank group, sham-operation group, model group, and electroacupuncture treatment groups 1, 2, and 3. Traumatic brain injury was induced by the modified Feeney free-fall impact device, and for the rats in the electroacupuncture treatment groups 1, 2, and 3, electroacupuncture started at 4 hours and on days 3 and 7, respectively, after modeling and lasted to day 14. The Morris water maze test was used to evaluate learning and memory ability, and immunofluorescence assay and Western blot were used to observe the changes in the expression of Fas and FasL in traumatic brain tissue. Compared with the blank group and the sham-operation group, the model group had a lower percentage of time spent in the target quadrant from the 3rd day folowing modeling; after electroacupuncture intervention, the electroacupuncture treatment groups showed a gradual increase in the time spent in the target quadrant, and on day 7,10 and 14, electroacupuncture treatment group 1 had a significantly higher percentage than the model group (P<0.05). On day 14, electroacupuncture treatment group 2 had a significantly higher percentage than the model group (P<0.05). After electroacupuncture intervention, all groups except the blank group and the sham-operation group had increases in the expression of Fas and FasL in brain tissue, which reached the highest level on day 7 after modeling and then tended to decrease; compared with electroacupuncture treatment groups 2 and 3 and the model group, electroacupuncture treatment group 1 had significant reductions in the expression of Fas and FasL (P<0.05, P<0.01); compared with electroacupuncture treatment group 3 and the model group, electroacupuncture treatment group 2 had significant decreases in the expression of Fas and FasL (P<0.05) on day 14 after modeling; compared with the model group, electroacupuncture treatment group 3 had significant reductions in the expression of Fas and FasL in brain tissue on day 14 after modeling (P<0.05). Early electroacupuncture intervention can regulate the apoptosis receptor pathway by down-regulating Fas and FasL to exert a therapeutic effect on traumatic brain injury and help with the recovery of cognition and memory ability after traumatic brain injury.

Pengujian Struktur Sepatu Kuda Bahan Komposit Polymeric Foam Berpenguat Fiberglass Menggunakan Uji Impak Jatuh Bebas

This study aims to determine the mechanical structure of polymeric foam reinforced with fiberglass horseshoes. Observations are focused on the average maximum impact force and the average maximum impact stress obtained from the free fall impact test. Testing the free fall impact structure with an impactor weight of 10 kg on five horseshoe test specimens 1, 2, 3, 4 and 5 with an impact distance of 2.5 meters, 2 meters, 1.5 meters, 1 meter and 0.5 meters, the results are horse shoe test specimens does not experience cracks / broken. The results obtained are in the form of the highest stress on the 1A test specimen with a stress value of 0.154 MPa and the maximum force found in the 1A test specimen of 874.95 N. with an impactor weight of 12.5 kg the test specimen cracks / breaks at a height of 3 m and 2.5 m, resulting in the highest impact stress value in sample 6B of 0.21 MPa and a force of 1185.5 N. then the force and stress will be higher but the level of damage will also be greater.

LncRNA HOTAIR Participates in Microglia Activation and Inflammatory Factor Release by Regulating the Ubiquitination of MYD88 in Traumatic Brain Injury.

Traumatic brain injury (TBI) is one of the leading causes of death worldwide. Long non-coding RNAs (LncRNAs) have been reported to be closely associated with various diseases, but their roles in TBI has not been fully elucidated. The purpose of this study was to elucidate the underlying mechanism of LncRNA HOTAIR in TBI-induced microglial activation and inflammatory factor release. In vivo mouse TBI model and in vitro microglia activation model were established by Feeney's free-fall impact method and by LPS stimulation, respectively. The expression of LncRNA HOTAIR in activated microglia was detected by qRT-PCR. After shRNA knocked down, the expressions of LncRNA HOTAIR and microglia activation marker Iba-1 in microglia were detected by qRT-PCR and Western blot and by ELISA that detected the concentration of inflammatory factor in cell culture supernatants. The relationship between LncRNA HOTAIR and MYD88 in mouse microglia BV2 cells was observed by RNA pull-down assay. Furthermore, the effect of LncRNA HOTAIR on MYD88 stability was assessed by cycloheximide (CHX)-chase and by immunoprecipitation and ubiquitination assays that analyzed MYD88 ubiquitination. LncRNA HOTAIR was abnormally highly expressed in activated microglia. By Western blot and ELISA, the knockdown of LncRNA HOTAIR in microglia significantly repressed microglia activation and inflammatory factor release. By RNA pull-down assay, LncRNA HOTAIR could bind to MYD88 protein. Besides, by cycloheximide (CHX)-chase and immunoprecipitation and ubiquitination assays, the overexpression of the LncRNA HOTAIR enhanced the stability of MYD88 protein and inhibited Nrdp1-mediated ubiquitination of MYD88 protein. After thetransfection of shRNA-HOTAIR and shRNA-HOTAIR+pcDNA-MYD88 into microglia, shRNA-HOTAIR could significantly inhibit the activation of microglia and the release of inflammatory factors, while these effects were reversed after the transfection of pcDNA-MYD88. Our experimental data indicated that LncRNA HOTAIR was highly expressed in activated microglia, and our further studies had found that theinterference with LncRNA HOTAIR could repress microglia activation and inflammatory factor release via promoting Nrdp1-mediated ubiquitination of MYD88 protein.

Effects of seawater immersion on open traumatic brain injury in rabbit model

We emulated instances of open traumatic brain injuries (TBI) in a maritime disaster. New Zealand rabbit animal models were used to evaluate the pathophysiological changes in open TBI with and without the influence of artificial seawater. New Zealand rabbits were randomly divided into 3 groups. Control group consisted of only normal animals. Animals in TBI and TBI + Seawater groups underwent craniotomy with dura mater incised and brain tissue exposed to free-fall impact. Afterward, only TBI + Seawater group received on-site artificial seawater infusion. Brain water content (BWC) and permeability of blood–brain barrier (BBB) were assessed. Reactive oxygen species levels were measured. Western blotting and immunofluorescence were employed to detect: apoptosis-related factors Caspase-3, Bax and Bcl-2; angiogenesis-related factors CD31 and CD34; astrogliosis-related factor glial fibrillary acidic protein (GFAP); potential neuron injury indicator neuron-specific enolase (NSE). Hematoxylin & eosin, Masson-trichrome and Nissl stainings were performed for pathological observations. Comparing to Control group, TBI group manifested abnormal neuronal morphology; increased BWC; compromised BBB integrity; increased ROS, Bax, CD31, CD34, Caspase-3 and GFAP expressions; decreased Bcl-2 and NSE expression. Seawater immersion caused all changes, except BWC, to become more significant. Seawater immersion worsens the damage inflicted to brain tissue by open TBI. It aggravates hypoxia in brain tissue, upregulates ROS expression, increases neuron sensitivity to apoptosis-inducing factors, and promotes angiogenesis as well as astrogliosis.

Performance Effects of Different Table Tennis Ball Materials

ABSTRACT The performance of two different table tennis balls (i.e. a seamless poly ball and a seamed celluloid ball) is compared both experimentally and numerically. No significant difference is found in the coefficients of restitution of the two balls in free-fall impact tests onto a flat rubber surface. However, the celluloid ball has a faster rotational speed on serving, while the poly ball has a greater rebound angle. However, on serving, the celluloid ball has a faster spinning speed than the poly ball, while the poly ball has a greater rebound angle. In addition, for a given spin rotation speed and serving speed, the celluloid ball has a faster sink velocity than the seamless poly ball.

Finite Volume method for general compressible naval hydrodynamics

An efficient, pressure-based segregated Finite Volume solution method for two-phase free surface flow simulations including compressibility effects is presented in this paper. Incompressible treatment of the heavier phase enables efficient long evolutions of wave fields without the need for a separate solver. Air is treated as an ideal gas undergoing isentropic compression/expansion, removing the need for an additional energy equation, and related numerical difficulties. The discontinuity in properties at the free surface between the two phases is treated using the Ghost Fluid Method, correctly accounting for the abrupt change in density and compressibility.Detailed verification and validation is conduced on three simple test cases comprising a liquid piston, free fall impact of a horizontal water column and a regular wave propagation to test the stability and accuracy for cases with and without significant compressibility effects. The present approach is compared with the incompressible formulation for industrial-grade simulations, showing that the same level of accuracy can be achieved without significant overhead in computational time. Finally, a compressible wave breaking impact from a large-scale experimental campaign is reproduced, showing that the method is capable of capturing trapped air cushioning effects with good accuracy.

Diammonium glycyrrhizinate promotes the regeneration and repair of central nervous system in rats with severe traumatic brain injury by Wnt/β-catenin signaling pathway

To observe the effects of diammonium glycyrrhizinate (DG) on nerve regeneration repair in rats with severe traumatic brain injury (STBI) from the perspective of Wnt/β-catenin signaling pathway. Seventy-two Sprague-Dawle (SD) male rats were randomly divided into normal group, STBI model group, ganglioside (GA) treatment group and DG treatment group. The STBI animal model was reproduced referring to modified Feeney free fall impact model. No injury was made in normal group. Six hours after modeling, monosialotetrahexosylganglioside sodium injection and DG injection were injected via tail vein of rats in GA treatment group and DG treatment group respectively, once a day for 7 days. Normal group and STBI model group were given the same amount of normal saline. Six rats in each group were sacrificed on the 1st, 3rd and 7th day after the challenge for neurological severity score (NSS), and then the blood of abdominal aorta was drawn and brain tissue was harvested. The contents of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in serum were detected by enzyme linked immunosorbent assay (ELISA). The pathological changes of sub-granular zone (SGZ) were observed under light microscope after hematoxylin eosin (HE) staining. Real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to detect the mRNA expressions of Wnt3a, β-catenin, glycogen synthetase kinase-3β (GSK-3β) and Axin. (1) There was no neurological deficit in the normal group and NSS was 0. NSS score of rats increased significantly on the first day after modeling, and then decreased gradually over time. NSS of the rats treated with GA and DG were significantly lower than that of the STBI model rats (score: 7.33±2.07, 6.17±2.23 vs. 9.33±1.63, both P < 0.01). Though NSS gradually decreased over time, the differences were still statistically significant on the 7th day (score: 2.67±0.82, 1.00±0.00 vs. 6.17±2.23, both P < 0.01), and NSS of DG treatment group was significantly lower than that of GA treatment group. (2) In SGZ of rats, cells were arranged in a compact and orderly way in the normal group, but neurons and tissues were damaged and destroyed at different time points in the STBI model group. After either GA or DG treatment, the damage of nerve tissue was improved gradually over time, and the effect of DG was more obvious. (3) In the normal group, the mRNA expressions of Wnt3a and β-catenin were almost not expressed, the mRNA expressions of GSK-3β and Axin were higher, and the contents of BDNF and NGF in serum were less. On the 1st day after STBI, the mRNA expressions of Wnt3a and β-catenin in hippocampus, the contents of BDNF and NGF in serum were significantly increased, and the mRNA expressions of GSK-3β and Axin were significantly decreased. The mRNA expressions of Wnt3a and β-catenin in the hippocampus and the contents of BDNF and NGF in serum were significantly higher than those in the model group 1 day after GA or DG was added, the mRNA expressions of GSK-3β and Axin were significantly decreased, and the effect of DG was more significant than that of GA [Wnt3a mRNA (2-ΔΔCt): 3.51±0.14 vs. 2.93±0.05, β-catenin mRNA (2-ΔΔCt): 1.90±0.08 vs. 1.75±0.04, BDNF (ng/L): 4.06±0.55 vs. 3.16±0.64, NGF (ng/L): 9.53±1.08 vs. 7.26±0.43, GSK-3β mRNA (2-ΔΔCt): 0.75±0.01 vs. 0.79±0.01, Axin mRNA (2-ΔΔCt): 0.74±0.02 vs. 0.76±0.02, all P < 0.05]. It was gradually increasing or decreasing over time and the difference was still statistically significant up to the 7th day. DG can promote the recovery of nerve function in rats with STBI, and its mechanism may be related to the regeneration of nerve cells proliferation and differentiation by Wnt/β-catenin signaling pathway and the reconstruction of nerve tissue in SGZ of hippocampus.

Comparative behavior of damping terms of viscoelastic contact force models with consideration on relaxation time

This paper presents a comparative investigation into behaviors of different damping terms of viscoelastic contact models, and introduces a novel damping term with dimensional reasoning analysis and by considering the effect of relaxation time of viscoelastic spheres. Behaviors of different contact models are compared in terms of predictions of non-dimensional variables, where the influence of damping parameters on behaviors of viscoelastic models is analyzed and the relationship between non-dimensional damping parameters and the coefficient of restitution is discussed. The damping parameter related to relaxation time is found to affect behaviors of the current viscoelastic contact model significantly. Viscoelastic models of different damping terms exhibit different behaviors, especially for a heavily damped case. Comparison between simulation and free fall impact test of viscoelastic balls demonstrates that the current contact model involving relaxation time fits experimental results better than other contact models.

Collagen-chitosan scaffold impregnated with bone marrow mesenchymal stem cells for treatment of traumatic brain injury.

Combinations of biomaterials and cells can effectively target delivery of cells or other therapeutic factors to the brain to rebuild damaged nerve pathways after brain injury. Porous collagen-chitosan scaffolds were prepared by a freeze-drying method based on brain tissue engineering. The scaffolds were impregnated with rat bone marrow mesenchymal stem cells. A traumatic brain injury rat model was established using the 300 g weight free fall impact method. Bone marrow mesenchymal stem cells/collagen-chitosan scaffolds were implanted into the injured brain. Modified neurological severity scores were used to assess the recovery of neurological function. The Morris water maze was employed to determine spatial learning and memory abilities. Hematoxylin-eosin staining was performed to measure pathological changes in brain tissue. Immunohistochemistry was performed for vascular endothelial growth factor and for 5-bromo-2-deoxyuridine (BrdU)/neuron specific enolase and BrdU/glial fibrillary acidic protein. Our results demonstrated that the transplantation of bone marrow mesenchymal stem cells and collagen-chitosan scaffolds to traumatic brain injury rats remarkably reduced modified neurological severity scores, shortened the average latency of the Morris water maze, increased the number of platform crossings, diminished the degeneration of damaged brain tissue, and increased the positive reaction of vascular endothelial growth factor in the transplantation and surrounding areas. At 14 days after transplantation, increased BrdU/glial fibrillary acidic protein expression and decreased BrdU/neuron specific enolase expression were observed in bone marrow mesenchymal stem cells in the injured area. The therapeutic effect of bone marrow mesenchymal stem cells and collagen-chitosan scaffolds was superior to stereotactic injection of bone marrow mesenchymal stem cells alone. To test the biocompatibility and immunogenicity of bone marrow mesenchymal stem cells and collagen-chitosan scaffolds, immunosuppressive cyclosporine was intravenously injected 12 hours before transplantation and 1-5 days after transplantation. The above indicators were similar to those of rats treated with bone marrow mesenchymal stem cells and collagen-chitosan scaffolds only. These findings indicate that transplantation of bone marrow mesenchymal stem cells in a collagen-chitosan scaffold can promote the recovery of neuropathological injury in rats with traumatic brain injury. This approach has the potential to be developed as a treatment for traumatic brain injury in humans. All experimental procedures were approved by the Institutional Animal Investigation Committee of Capital Medical University, China (approval No. AEEI-2015-035) in December 2015.

A computational study of the EN 1078 impact test for bicycle helmets using a realistic subject-specific finite element head model

In the present study, the free fall impact test in accordance with the EN1078 standard for certification of bicycle helmets is replicated using numerical simulations. The impact scenario is simulated using an experimentally validated, patient-specific head model equipped with and without a bicycle helmet. Head accelerations and intracranial biomechanical injury metrics during the impacts are recorded. It is demonstrated that wearing the bicycle helmet during the impact reduces biomechanical injury metrics, with the biggest reduction seen in the metric for skull fracture.

A Model for the Design of a Pomelo Peel Bioinspired Foam

The structure of pomelo peel arouses research interest in recent years because of the outstanding damping and energy dissipating performance of the pomelo peel. Researchers found that pomelo peel has varying pore size through the peel thickness; the pore size gradient is one of the key reasons leading to superior energy dissipation performance of pomelo peel. In this paper, we introduce a method to model pomelo peel bioinspired foams with nonuniform pore distribution. We generate the skeletal open cell structure of the bioinspired foams using Voronoi tessellation. The skeleton of the bioinspired foams is built as three-dimension (3D) beam elements in a full-scale finite element model. The quasi-static and dynamic mechanical behaviors of the pomelo peel bioinspired foams could be derived through a finite element analysis (FEA). We illustrate our method using a case study of pomelo peel bioinspired aluminum foams under quasi-static compression and free fall impact circumstances. The case study results validate our method and demonstrate the superior impact resistance and damping behavior of bioinspired foam with gradient porosity for designers.

Damage characterization of sandwich composites subjected to impact loading

Advanced composite materials are usually optimized to achieve balance of properties for given range of applications. In recent times, researchers had worked on the sandwich composites by using different foam and metal honeycomb as a core material. In the current project, honeycomb core is prepared by using 3D printed technology. In this case of sandwich composites, cross-linked polyethylene foam and 3D-printed polylactic acid honeycomb as core and GFRP is used as face sheet. The comparison is made between polyethylene foam and 3D printed honeycomb core sandwich composite in the aspect of toughness, strength, and modulus. The present study is to characterize the damages in the sandwich structure for the amount of energy absorbed by the structures such as delamination, indentation, crushing of foams, and debonding of face sheets and core material subjected to free fall impact. The contact force versus time, contact force versus deflection of plates with respect to impact energy levels of 9.3, 16.5, and 25.7 J and impact energy versus time are determined. The current research helps in determination of core materials effecting/absorbing the damage and behavior of sandwich materials subjected to impact loads.

Investigation on Potential of Recycle Plastic Bottles as a Crash Cushion for Road Barrier

Road accident is a major problem in the country and should be dealt with an effective ways. Road furniture is one of the factors that contributing an accidents than other factors. Therefore, this study focuses on waste material such as recycle plastic bottle that potential to be used as a road barrier and crash cushion. The objective of this study are to investigate the potential of plastic bottles filled with sand as crash cushion, examine the impact strength of plastic bottles and designing crash cushion by using recycled materials. Some plastic bottles of soft drinks containing ordinary sand was prepared and undergone experimental and simulation works. Free fall Impact test that imposed on the plastic bottles has been carried out to identify the strength and its energy absorption. The numerical simulation of impact test was conducted using Finite Element Method to obtain impact failure and to observe its details response under low velocity impact loads. The numerical results by employing FEM well agreed with practical works. Where, the absorption of energy from the impact test shows that the difference does not exceed 50%. In addition, the deformation of both test are almost similar. Therefore, the use of recycled materials such as plastic bottles filled with sand as crash cushions that can be considered as alternative and environmentally friendly materials.

Effect of hydrogen-rich water on the chondriosome damage and cytokines in brain tissue of rats with traumatic brain injury

To observe the effect of hydrogen-rich water on the chondriosome damage and cytokines change in brain tissue of rats with traumatic brain injury (TBI). Fifty-four health male Sprague-Dawley (SD) rats were divided into three groups by random number table: sham group, trauma group (TBI group), and trauma+hydrogen-rich water group (TBI+HW group), the rats in each group were subdivided into 1, 3 and 7 days subgroups according to the time points after trauma, with 6 rats in each subgroup. The TBI model was reproduced by using a modified Feency method for free fall impact, and the rats in sham group were not given brain impact after craniotomy. The rats in TBI+HW group were given intraperitoneal injection of hydrogen-rich water (5 mL/kg) after TBI model reproduction, and then once a day until being sacrificed; and the rats in sham group and TBI group were given the same amount of normal saline. The neurological severity scores (NSS) for neurologic deficits were calculated at corresponding time points, and then the rats were sacrificed to harvest brain tissue at 3 mm around lesion boundary. The cytokines including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were determined by enzyme linked immunosorbent assay (ELISA); the protein expressions of Bax, Bcl-2 were determined by Western Blot; the RFU of reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and mitochondrial membrane permeability (MPTP) were determined by fluorescence and enzyme sign method. TBI and TBI+HW groups appeared obvious neurologic damage after injury in rats. NSS scores in TBI and TBI+HW groups showed a decreased tendency with time prolongation after TBI. NSS scores in TBI+HW group at 3 days and 7 days were significantly lower than those of TBI group (NSS score: 9.67±0.82 vs. 11.17±1.17, 6.83±0.75 vs. 8.50±1.04, both P < 0.05). Compared with sham group, the expressions of TNF-α, IL-1β, RFU of ROS in chondriosome, protein expression of Bax in brain tissue in TBI group and TBI+HW group were significantly increased, peaked at 1 day, then they gradually declined. Each time point of RFU of MMP, MPTP in chondriosome and protein expression of Bcl-2 were significantly decreased, and gradually increased after one-day valley value. Compared with TBI group, the expressions of TNF-α, IL-1β, RFU of ROS in chondriosome and protein expression of Bax in brain tissue were all declined at corresponding time points [TNF-α (ng/L): 54.14±1.11 vs. 81.49±2.76, IL-1β (ng/L): 74.53±1.75 vs. 119.44±3.56, ROS (RFU): 92.30±2.46 vs. 121.33±6.57, Bax: 0.89±0.01 vs. 1.10±0.01, all P < 0.01]; RFU of MMP, MPTP in chondriosome and the protein expression of Bcl-2 were all increased at corresponding time points [MMP (RFU): 99.28±3.97 vs. 74.72±3.00, MPTP (RFU): 188.82±4.44 vs. 160.01±2.04, Bcl-2: 0.52±0.02 vs. 0.30±0.02, all P < 0.01]. The high expressions of cytokines and chondriosome damage were involved in the early TBI. Early treatment with an intraperitoneally injection of hydrogen-rich water can reduce chondriosome damage and inflammation factor release, reduce the nerve cell apoptosis after TBI, and protect brain function.

Manufacture and impact analysis of bmx helmet made from polymeric foam composite strengthened by oil palm empty fruit bunch fiber

Helmets are protective head gears wear by bicycle riders for protection against injury in case of the accident. Helmet standards require helmets to be tested with a simple drop test onto an anvil. The purpose of research is to know toughness of bicycle helmet made from polymeric foam composite strengthened by oil palm empty fruit bunch fiber. This research contains report result manufacture and impacts analysis of bicycle helmet made from polymeric foam composite materials strengthened by oil palm empty fruit bunch fiber (EFB). The geometric helmet structure consists of shell and liner; both layers have sandwich structure. The shell uses matrix unsaturated Polyester BQTN-157EX material, chopped strand mat 300 glass fiber reinforce and methyl ethyl ketone peroxide (MEKPO) catalyst with the weight composition of 100 gr, 15 gr, and 5 gr. The liner uses matrix unsaturated Polyester BQTN-157 EX material, EFB fiber reinforces, Polyurethane blowing agent, and MEKPO catalyst with the composition of 275 gr (50%), 27.5 gr (5%), 247 gr (45%), and 27.5 gr (5%). Layers of the helmet made by using hand lay-up method and gravity casting method. Mechanical properties of polymeric foam were the tensile strength (ơt) 1.17 Mpa, compressive strength (ơc) 0.51 MPa, bending strength (ơb) 3.94 MPa, elasticity modulus (E) 37.97 Mpa, density (ρ) 193 (kg/m3). M4A model helmet is the most ergonomic with the thickness 10 mm and the amount of air channel 11. Free fall impact test was done in 9 samples with the thickness of 10 mm with the height of 1.5 m. The result of the impact test was impacted force (Fi) 241.55 N, Impulse (I) 6.28 Ns, impact Strength (ơi) 2.02 Mpa and impact Energy (Ei) 283.77 Joule. The properties of bicycle helmet model BMX-M4A type was 264 mm length, 184 mm width, 154 mm height, 10 mm thick, 580 mm head circle, 331 g mass and 11 wind channels.

Analisa Kekuatan Impak Helmet Sepeda Motor Metode Impak Jatuh Bebas

The non-standard helmet testing is required for measure the helmet strength as effect of the load is given. In generally, traffic accident doesn�t involved by the velocity but also gravitational. Therefore, the research activity is done by researcher obtains the effect of free-fall impact loading on the non-standard helmet. The information which is obtained from this research will explain the effect of free-fall impact loading that is subjected on the non-standard helmet to user, industry, and also government. The objective of this research involves the testing apparatus construction of free-fall impact loading on the non-standard helmet, measuring the maximum impact loading, and the energy absorbing by helmet as effect of impact loading. The researcher collaborates with the Impact and Fracture Reaseach Center (IRFC) has bulit the testing apparatus which is equipped with good aquisition data system. The non-standar helmet is put on the adjustable testing rig. The impact time can be measured by eight inductive proximity sensors. The helmet will slide down and collides the anvil. The force will be measured with the load cell which is put down the anvil. There are four anvil forms which is adapted to the real condition, that is: flat plat, aligned plat, bullet, and a half-spherical anvil. The data will be transfered from the load cell into the DAQ system which has function to change the analog into digital signal. Finally, the data will be saved into PC as the force (N) and the impact time (ms). The free-fall impact testing equipment has shown the best performance on the force and impact time signal reading as long as the research activity. The maximum force on the flat anvil is 24.33 N; the aligned flat anvil is 37.88 N; the bullet anvil is 16.22 N; and a half-spherical anvil is 41.43 N at the elevation of 0.75 m. The minimum energy which causes the fracture on the helmet is 3.24 J at the elevation of 0.3 m.

Estimation of the Compressive Strength of Intact Rock Using Non-Destructive Testing Method Based on Total Sound-Signal Energy

This study proposes a new non-destructive testing (NDT) method to assess the compressive strength of intact rock. The method is based on total sound-signal energy, which is calculated using the sound signal generated from impacting intact rock. A device was developed to generate an impact sound from a test object using a rotating free-falling impact ball and subsequent repetitive impacts from the rebound action. To validate the method, soil cement, cement paste, pine wood, shale, and granite specimens were first tested to determine the correlation between the direct compressive strength and the total sound-signal energy. Next, the method was applied to a number of shale and granite specimens. The results show a direct relationship between the direct compressive strength and the total sound-signal energy. Correlation equations between the total sound-signal energy and the direct compressive strength were determined for the different rock types, both separately and together through regression analysis. Then, the determined correlation equations were used to estimate the strength of intact rock and validate the method. Statistical analysis indicated that the estimated compressive strength was quite reliable for both rock types. It is expected that the new NDT test method could play a meaningful role in non-destructively estimating the compressive strength of intact rock in the future.

ANALISIS KOMPUTASI TEGANGAN AKIBAT UJI JATUH BEBAS DENGAN KETINGGIAN 3 METER PADA KOMPOSIT YANG DIGUNAKAN SEBAGAI PELINDUNG DADA PENGENDARA SEPEDA MOTOR

The goal of this research is to identify computationally the stress and force that occur in the motor bike body protector which created using composite material. This test is done using ANSYS software. Test is using explicit dynamic with the free-fall impact methods which make the speciment crashed to the anvil. From the test the impact force transmitted is 14.95 kN and with the stress 0.014952 Mpa. Average impact force that occur is 29.18 Mpa which is compared with the EN 1621-3 standarization limit which is 35 kN in order to determine if this body protector is consentient with the standard.