Maximum Peak Pressure Research Articles

Experimental shock metamorphism of the L4 ordinary chondrite Saratov induced by spherical shock waves up to 400 GPa

Abstract– We carried out shock experiments on macroscopic spherical samples of the L4 ordinary chondrite Saratov (natural shock stages S2–S3), using explosively generated spherical shock waves with maximum peak pressures of 400 GPa and shock-induced temperatures >800 °C (up to several thousands °C). The evolution of shock metamorphism within a radius of the spherical samples was investigated using optical and scanning electron microscopy, microprobe and magnetic analyses as well as Mossbauer spectroscopy and X-ray diffraction techniques. Petrographic analyses revealed a shock-induced formation of three different concentric petrographic zones within the shocked samples: zone of total melting (I), zone of partial melting (II), and zone of solid-state shock features (III). We found a progressive pressure-induced oxidation of Fe-Ni metal, whose degree increased with increasing shock peak pressure. The amount of FeO within zone I increased the factor of 1.4 with respect to its amount in the unshocked Saratov sample. This suggests that within zone I about 70 wt% of the initial metallic iron was oxidized, whereas magnetic analyses showed that about 10 wt% of it remained intact. This strongly supports the hypothesis that, in addition to oxidation, a migration of metallic iron from the central heavily shocked zone I toward less shocked peripheral zone took place as well (likely through shock veins where metallic droplets were observed). Magnetic analyses also showed a shock-induced transformation of tetrataenite to taenite within all shocked subsamples, resulting in magnetic softening of these subsamples (decrease in remanent coercivity). These results have important implications for extraterrestrial paleomagnetism suggesting that due to natural impact processes, the buried crustal rocks of heavily cratered solid solar system bodies can have stronger remanent magnetism than the corresponding surface rocks.

Experimental investigation of air pockets in pumping pipeline systems

Air in pipelines may cause insignificant to severe operational difficulties. If air pockets remain at high points of pumping pipelines, they can cause problems such as a reduction of the effective pipe cross-section, resulting in an increase of head losses. Air pockets can amplify the maximum peak pressures during transients and cause pipe failure. To study large air pockets located at high points in pumping pipelines, experimental investigations were conducted to corroborate that the flow underneath a large air pocket under pressurized flow conditions can be considered similar to gradually varied open channel flow. The hydraulic grade line at pressurized flow conditions was measured with and without air pockets in the test section of the experimental apparatus to verify its effect on the head losses.

Influence of obesity and sarcopenic obesity on plantar pressure of postmenopausal women

Background Menopause is associated with a decrease in fat-free mass and an increase in fat mass. Sarcopenic obesity is more strongly associated with physical limitations than either obesity or sarcopenia and their effect in plantar pressure is not known. Consequently, the scope of the present study was to examine the effect of obesity and sarcopenic obesity on plantar pressure of postmenopausal women, during walking. Methods Body composition and biomechanics parameters of plantar pressure were assessed in 239 postmenopausal women. Findings Compared to non-obese and non-sarcopenic women, obese postmenopausal women have higher peak pressure in the metatarsal areas 1, 4, 5, midfoot and lateral heel and higher absolute impulses in all metatarsal and heel areas. On the other hand, sarcopenic obese postmenopausal women presented higher peak pressure and absolute impulses under all metatarsal areas, midfoot and heels. When the absolute values of maximal peak pressures and absolute impulses were normalised to body mass, pressure increases were only perceived for midfoot. Interpretation The pressure increase found in different foot areas of obese and particularly in sarcopenic obese could cause discomfort and pain in the foot. Sarcopenic obese postmenopausal women also present a higher loading during the stance phase comparing with non-sarcopenic non-obese, fact that might limit their basic daily activity tasks, such as walking.

Reliability of the TekScan MatScan®system for the measurement of plantar forces and pressures during barefoot level walking in healthy adults

BackgroundPlantar pressure systems are increasingly being used to evaluate foot function in both research settings and in clinical practice. The purpose of this study was to investigate the reliability of the TekScan MatScan® system in assessing plantar forces and pressures during barefoot level walking.MethodsThirty participants were assessed for the reliability of measurements taken one week apart for the variables maximum force, peak pressure and average pressure. The following seven regions of the foot were investigated; heel, midfoot, 3rd-5th metatarsophalangeal joint, 2nd metatarsophalangeal joint, 1st metatarsophalangeal joint, hallux and the lesser toes.ResultsReliability was assessed using both the mean and the median values of three repeated trials. The system displayed moderate to good reliability of mean and median calculations for the three analysed variables across all seven regions, as indicated by intra-class correlation coefficients ranging from 0.44 to 0.95 for the mean and 0.54 to 0.97 for the median, and coefficients of variation ranging from 5 to 20% for the mean and 3 to 23% for the median. Selecting the median value of three repeated trials yielded slightly more reliable results than the mean.ConclusionsThese findings indicate that the TekScan MatScan® system demonstrates generally moderate to good reliability.

Novel nanoenergetic system based on iodine pentoxide

We report the first study of the gas generation and thermal wave behavior during the performance of the novel nanoenergetic system based on aluminum and iodine pentoxide nanoparticles. The homogeneous mixture of Al/I 2O 5 ignited in the range of 605–620 °C and generated a thermal front that propagated through the sample with a velocity of ∼2000 m/s. The maximum peak pressure of up to 11 MPa ( m = 0.5 g) was generated by a mixture containing ∼78 wt% of I 2O 5. The maximum pressure × volume PV-value for a 0.5 g sample was ∼3.8 kPa m 3 is comparable to that generated by the same sample mass of the Bi 2O 3/Al system.

Parametric Finite Element Analysis of Physical Stimuli Resulting From Mechanical Stimulation of Tissue Engineered Cartilage

While mechanical stimulation of cells seeded within scaffolds is widely thought to be beneficial, the amount of benefit observed is highly variable between experimental systems. Although studies have investigated specific experimental loading protocols thought to be advantageous for cartilage growth, less is known about the physical stimuli (e.g., pressures, velocities, and local strains) cells experience during these experiments. This study used results of a literature survey, which looked for patterns in the efficacy of mechanical stimulation of chondrocyte seeded scaffolds, to inform the modeling of spatial patterns of physical stimuli present in mechanically stimulated constructs. The literature survey revealed a large variation in conditions used in mechanical loading studies, with a peak to peak strain of 10% (i.e., the maximum amount of deformation experienced by the scaffold) at 1 Hz on agarose scaffolds being the most frequently studied parameters and scaffold. This loading frequency was then used as the basis for simulation in the finite element analyses. 2D axisymmetric finite element models of 2x4 mm2 scaffolds with 360 modulus/permeability combinations were constructed using COMSOL MULTIPHYSICS software. A time dependent coupled pore pressure/effective stress analysis was used to model fluid/solid interactions in the scaffolds upon loading. Loading was simulated using an impermeable frictionless loader on the top boundary with fluid and solid displacement confined to the radial axis. As expected, all scaffold materials exhibited classic poro-elastic behavior having pressurized cores with low fluid flow and edges with high radial fluid velocities. Under the simulation parameters of this study, PEG scaffolds had the highest pressure and radial fluid velocity but also the lowest shear stress and radial strain. Chitosan and KLD-12 simulated scaffold materials had the lowest radial strains and fluid velocities, with collagen scaffolds having the lowest pressures. Parametric analysis showed maximum peak pressures within the scaffold to be more dependent on scaffold modulus than on permeability and velocities to depend on both scaffold properties similarly. The dependence of radial strain on permeability or modulus was more complex; maximum strains occurred at lower permeabilities and moduli, and the lowest strain occurred at the stiffest most permeable scaffold. Shear stresses within all scaffolds were negligible. These results give insight into the large variations in metabolic response seen in studies involving mechanical stimulation of cell-seeded constructs, where the same loading conditions produce very different results due to the differences in material properties.

Vacuum cushioned removable cast walkers reduce foot loading in patients with diabetes mellitus

BackgroundDiabetes mellitus is one of the most common diseases worldwide and the number of patients is expected to increase dramatically in future. Plantar ulceration is partly caused by high plantar pressures and a major complication in diabetic patients. PurposeThe aim of this study was to investigate the pressure-relieving effects of two vacuum orthoses in patients with diabetes mellitus. MethodsTwenty patients with diabetes mellitus were included. They presented with plantar callosities but no ulceration. Exclusion criteria included the use of walking aids and other systemic diseases. Plantar pressure distribution was measured with sensor insoles (Pedar-X, Novel GmbH) during walking in two vacuum orthoses, a post-operative shoe and an off-the-shelf shoe as reference condition. Statistical analysis was conducted using Friedman and Wilcoxon signed-rank tests. ResultsSignificant differences in plantar pressure distribution were found between the four walking conditions. The contact area increased in the midfoot with the vacuum orthoses. Maximum force and peak pressures showed a significant decrease under the rearfoot and forefoot and increased in the midfoot area during walking with both vacuum orthoses. The high-cut vacuum orthosis revealed equal pressure relief under the forefoot and significantly lower rearfoot pressures compared to the post-operative shoe. ConclusionsThe vacuum orthoses demonstrated a comparable pressure-relieving efficacy under the forefoot to post-operative shoes. Using vacuum orthosis significantly benefited re-distribution of plantar pressure and the roll-over process. Clinical significance of the pressure-relieving efficacy could not be confirmed in this investigation and has to be addressed in further studies.

Pedobarographic Analysis Following Ponseti Treatment for Congenital Clubfoot

Current methods of treating congenital clubfeet provide high rates of functional outcomes. Despite the clinical outcomes, radiographic assessment suggests residual equinus deformity of the hindfoot. It is unclear whether these deformities result in abnormal foot-floor pressures and whether they correlate with clinical outcome. We evaluated 28 feet in 20 patients following Ponseti treatment for clubfoot by clinical and pedobarographic examination a mean of 33 months after removal of the last cast. The data were compared to age- and weight-matched normal subjects and to the unaffected foot in the unilaterally affected patients. Despite ankle range of motion of 30 degrees and a physiologic hindfoot valgus alignment in 19 cases, pedobarography suggested differences in maximum force, impulse, contact area, and peak pressure compared to normal subjects. Compared to the unaffected foot the only difference was reduced peak pressure over the medial hindfoot and forefoot with increased pressure over the lateral midfoot. Similar to radiographic abnormalities in studies on treated clubfeet with good functional outcome, pedobarographic analyses show differences compared to a control group. The value of pedobarographic analysis for predicting successful treatment of congenital clubfoot is questionable since it does not correlate with the clinical outcome in patients treated with the Ponseti method. Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Differences in plantar loading between training shoes and racing flats at a self-selected running speed

The purpose of this study was to examine the difference in plantar loading between two different running shoe types. We hypothesized that a higher maximum force, peak pressure, and contact area would exist beneath the entire foot while running in a racing flat when compared to a training shoe. 37 athletes (17 male and 20 female) were recruited for this study. Subjects had no history of lower extremity injuries in the past six months, no history of foot or ankle surgery within the past 3 years, and no history of metatarsal stress fractures. Subjects had to be physically active and run at least 10 miles per week. Each subject ran on a 10 m runway 7 times wearing two different running shoe types, the Nike Air Pegasus (training shoe) and the Nike Air Zoom Katana IV (racing flat). A Pedar-X in-shoe pressure measurement system sampling at 50 Hz was used to collect plantar pressure data. Peak pressure, maximum force, and contact area beneath eight different anatomical regions of the foot as well as beneath the total foot were obtained. The results of this study demonstrated a significant difference between training shoes and racing flats in terms of peak pressure, maximum force, and contact area. The significant differences measured between the two shoes can be of importance when examining the influence of shoe type on the occurrence of stress fractures in runners.

Efficacy of intra‐articular hyaluronan (Synvisc®) for the treatment of osteoarthritis affecting the first metatarsophalangeal joint of the foot (hallux limitus): study protocol for a randomised placebo controlled trial

BackgroundOsteoarthritis of the first metatarsophalangeal joint (MPJ) of the foot, termed hallux limitus, is common and painful. Numerous non-surgical interventions have been proposed for this disorder, however there is limited evidence for their efficacy. Intra-articular injections of hyaluronan have shown beneficial effects in case-series and clinical trials for the treatment of osteoarthritis of the first metatarsophalangeal joint. However, no study has evaluated the efficacy of this form of treatment using a randomised placebo controlled trial. This article describes the design of a randomised placebo controlled trial to evaluate the efficacy of intra-articular hyaluronan (Synvisc®) to reduce pain and improve function in people with hallux limitus.MethodsOne hundred and fifty community-dwelling men and women aged 18 years and over with hallux limitus (who satisfy inclusion and exclusion criteria) will be recruited.Participants will be randomised, using a computer-generated random number sequence, to receive a single intra-articular injection of up to 1 ml hyaluronan (Synvisc®) or sterile saline (placebo) into the first MPJ. The injections will be performed by an interventional radiologist using fluoroscopy to ensure accurate deposition of the hyaluronan in the joint. Participants will be given the option of a second and final intra-articular injection (of Synvisc® or sterile saline according to the treatment group they are in) either 1 or 3 months post-treatment if there is no improvement in pain and the participant has not experienced severe adverse effects after the first injection. The primary outcome measures will be the pain and function subscales of the Foot Health Status Questionnaire. The secondary outcome measures will be pain at the first MPJ (during walking and at rest), stiffness at the first MPJ, passive non-weightbearing dorsiflexion of the first MPJ, plantar flexion strength of the toe-flexors of the hallux, global satisfaction with the treatment, health-related quality of life (assessed using the Short-Form-36 version two questionnaire), magnitude of symptom change, use of pain-relieving medication and changes in dynamic plantar pressure distribution (maximum force and peak pressure) during walking. Data will be collected at baseline, then 1, 3 and 6 months post-treatment. Data will be analysed using the intention to treat principle.DiscussionThis study is the first randomised placebo controlled trial to evaluate the efficacy of intra-articular hyaluronan (Synvisc®) for the treatment of osteoarthritis of the first MPJ (hallux limitus). The study has been pragmatically designed to ensure that the study findings can be implemented into clinical practice if this form of treatment is found to be an effective treatment strategy.Trial registrationAustralian New Zealand Clinical Trials Registry: ACTRN12607000654459

Percutaneous Distal Soft Tissue Release–Akin Procedure, Clinical and Podobarometric Assessment With the BioFoot In-Shoe System

Hallux valgus (HV) is a common, complex, and progressive deformity of the first ray, leading to biomechanical changes. The purpose of this study is to describe the midterm outcomes of the percutaneous distal soft tissue release-Akin procedure for mild hallux valgus on plantar pressures distribution, clinical outcome, and radiographic parameters. Twenty-six patients (30 feet) who had undergone this procedure were evaluated prospectively. The BioFoot in-shoe system was used for an objective functional evaluation of dynamic plantar pressures in the heel, midfoot, first through fifth metatarsal heads, hallux, and lesser toes. The clinical outcome measurements included preoperative and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) score. The radiological parameters measured were hallux abductus angle (HAA) and first intermetatarsal angle in weight-bearing radiographs. The average follow-up was 12.1 months. There were improvements in the AOFAS rating scale score from 68.7 to 88.1, in HAA from 25.4 degrees to 11.4 degrees, and in the first intermetatarsal angle from 12.0 degrees to 9.2 degrees. The pedobarographic analysis showed a statistically significant decrease (P < .001) in the maximum peak pressure (from 1037 to 498 kPa) and mean pressure (from 487 to 159 kPa) under the hallux. The percutaneous distal soft tissue release-Akin procedure improved the patients' clinical status and reduced the plantar pressures beneath the hallux. This improvement could be attributable to the removal of the medial eminence, which avoids pain around the first metatarsophalangeal joint, and to the Akin procedure, which provides a more physiological postoperative position of the hallux.

Plantar pressure distribution in older people with osteoarthritis of the first metatarsophalangeal joint (hallux limitus/rigidus)

The purpose of this study was to evaluate differences in dynamic plantar pressure distribution between older people with and without radiographically confirmed osteoarthritis (OA) of the first metatarsophalangeal joint (first MPJ) of the foot. Dynamic plantar pressure recordings using the TekScan MatScan system were obtained during barefoot level walking in 40 older participants; 20 with radiographically confirmed OA of the first MPJ displaying less than 55 degrees of passive dorsiflexion, and 20 with no evidence of OA in the first MPJ displaying greater than 55 degrees of passive dorsiflexion. Group comparisons between the variables maximum force and peak pressure were made for seven different regions underneath the right foot (heel, midfoot, first MPJ, second MPJ, third to fifth MPJs, hallux, and lesser toes). Compared to the control group, participants with OA of the first MPJ exhibited 34% greater maximum force (7.9 +/- 2.5 vs. 5.9 +/- 1.7 kg, p = 0.005) and 23% higher peak pressure (1.6 +/- 0.3 vs. 1.3 +/- 0.3 kg/cm(2), p = 0.001) under the hallux. Similar results were also found under the lesser toes with 43% greater maximum force (5.0 +/- 1.9 vs. 3.5 +/- 1.4 kg; p = 0.006) and 29% higher peak pressure (0.9 +/- 0.2 vs. 0.7 +/- 0.2 kg/cm(2), p = 0.018). No significant differences were found to exist between groups for any other plantar region. These findings indicate that OA of the first MPJ is associated with significant changes in load-bearing function of the foot, which may contribute to the development of secondary pathological changes associated with the condition, such as plantar callus formation and hyperextension of the hallux interphalangeal joint.

The effect of foot type on in-shoe plantar pressure during walking and running

The purpose of this study was to determine if low arch feet have altered plantar loading patterns when compared to normal feet during both walking and running. Fifty healthy subjects (34 normal feet, 16 flat feet) walked and ran five trials each at standard speeds. In-shoe pressure data were collected at 50 Hz. Contact area, peak pressure, maximum force, and force-time integral were analyzed in eight different regions of the foot. Foot type was determined by examining navicular height, arch angle, rearfoot angle, and a clinical score. A series of 2 × 2 repeated measures ANOVAs were used to determine statistical differences ( α < 0.05). A significant interaction existed between foot type and movement type for the maximum force in the medial midfoot. Total foot contact area, maximum force and peak pressure were significantly increased during running. Contact area in each insole area, except for the rearfoot, was significantly increased during running. Peak pressure and maximum force were significantly increased during running in each of the foot regions. However, the force-time integral was significantly decreased during running in the rearfoot, lateral midfoot, middle forefoot, and lateral forefoot. Significant differences between foot types existed for contact area in the medial midfoot and maximum force and peak pressure in the lateral forefoot. The maximum force and peak pressures were significantly decreased for the flat foot type. Therefore, individuals with a flat foot could be at a lower risk for lateral column metatarsal stress fractures, indicating that foot type should be assessed when determining an individual's risk for metatarsal stress fractures.

EMG AND PLANTAR PRESSURE PATTERNS AFTER PROLONGED RUNNING

The aim of this paper is to investigate the effect of prolonged running on lower limb muscle activity, foot pressure and foot contact area. The treadmill running test was performed at a running velocity of 12 km/h for 20 minutes. Twenty-nine male students from the Army Infantry School took part in this study. For all subjects in our study, a number of variables were analyzed by the prolonged running. The EMG variables included the signal maximum amplitude of EMG linear envelope of all the muscles. Meanwhile, maximal forces and peak foot pressures in 10 anatomically defined areas of the foot, and contact area of the whole foot were analyzed. Running EMG data in each of the phases (phase 2–4) were compared to those at the beginning of the run (phase 1). Dynamic pedography data in phase 4 was compared to those of phase 1. Pedography analysis revealed a significant increase in the maximal forces and peak pressures under the medial midfoot and all forefoot regions. From phase 1 to phase 4, the maximal force increased by 32% under the medial midfoot, 29% under the first metatarsal, 34% under the second and third metatarsal, and 21% under the fourth and fifth metatarsal. The peak pressure under the medial midfoot increased by 19%, under the first metatarsal increased by 21%, under the second and third metatarsal increased by 31%, and under the fourth and fifth metatarsal increased by 21%. The averaged maximum EMG amplitudes of almost all the muscles were increased gradually as time increased. Among them, rectus femoris, gastrocnemius, soleus, and tibialis anterior muscles reach a significant amplitude at the p &lt; 0.05 level. In conclusion, our results showed that a prolonged running under a 20 minutes limitation led to a greater increase in muscle amplitude, midfoot and forefoot loading compared with the beginning of running.

Estudio baropodométrico de los valores de presión plantar en pies no patológicos

Background This study aimed to evaluate normal plantar pressures in healthy subjects using an electronic baropodometry. Material and methods Forty-six healthy subjects, with no clear foot or lower limb diseases, were analyzed with the Biofoot ® (IBV, Valencia, Spain) in-shoe system. The Biofoot system uses insoles with 64 piezoelectric sensors. Heel, midfoot and forefoot pressures were measured in 6 second recordings for each subjects. Maximum pressure peak and mean pressure was calculated and analyzed. Results Mean contact time was 0.81 (standard deviation [SD] 0.08) seconds in the right foot and 0.82 (SD 0.09) seconds in the left foot. Walking cadency was 105.6 (SD 8.4) steps per minute. Maximum peak and mean pressure in the heel was 750 and 253 kPa, respectively. In the midfoot, peak pressure was 400 kPa and mean pressure 65 kPa. The values found in the forefoot was 1,240 kPa for pressure peak and 220 kPa for mean pressure. Discussion The highest pressure peaks were found in the forefoot, followed by the heel and finally in the midfoot. In relationship to mean pressure, percentage of heel support is 46.4 %, that of the midfoot 12 % and forefoot 41.6 %. No correlation was found between cadence and pressure values with the number of patients analyzed in this study, however, there was a significant and positive correlation of weight with the pressure values in all the regions.

In vitro measurement of pressure differences using manometry at various injection speeds during discography

Lumbar discography has been widely used to evaluate discogenic low back pain. Anecdotal evidence suggests that pain reproduction during discography is more closely correlated with peak dynamic pressure than with static postinjection pressure. Although there can be a significant difference between dynamic and static pressures, to date most discographic evaluations use static pressure recorded postinjection (which is stable and easily measured). The use of readings taken after injection, rather than readings of maximum dynamic peak pressure recorded during injection, appear to increase false positives in lumbar discography. High-speed intradiscal injections also appear to have potentially confounding effects that may increase the rate of false-positive responses during lumbar discography. To date there has been no study for the evaluation of peak dynamic intradiscal pressures or for differentiating dynamic from static pressures in the nucleus pulposus (NP) in response to various speeds of intradiscal injection. The goal of this study was to obtain additional data on potential confounding factors that could affect discographic results by assessment of pressures within the NP during discography at various injection speeds. The purpose of data collection was to more precisely evaluate pressure differences between dynamic and static pressure within the NP, evident during discography. In vitro laboratory study. A total of 82 trials were performed on intervening discs of 82 porcine cadaver lumbar spines. Dynamic and static intradiscal pressures were measured with manometry, using two pressure sensors simultaneously during intradiscal injection of contrast media at various speeds. The tip of a 25-gauge needle was placed in the center of the NP and connected with a pressure manometer, which recorded the pressure and therefore the speed of injection. A second pressure reading was obtained using a sensor tip connected to a transducer; the sensor tip was located separately in the same NP tissue. The needle and transducer locations were confirmed by fluoroscopy. At low controlled injection speeds (below 0.08 mL/s), the mean peak pressure difference in the NP was 4.06 (+/-1.52) psi. With high-speed injections of 0.08 mL/s or greater, the mean increased abruptly up to 14.52 (+/-4.11) psi (p<.05). The data indicate that injections applied slowly resulted in smaller differences in pressure within the NP, registered by both manometry and the needle sensor tip. Additional samples were taken using both devices to confirm this threshold level. With low injection speeds, especially those below 0.08 mL/s, differences between dynamic and static pressures on both pressure sensors were minor. These differences increased as injection speed became faster. However, at fast injection speeds of 0.08 mL/s and above, those differences were significantly higher. Dynamic and static intradiscal pressures are of similar value when measured by manometer and by needle sensor at slow injection speeds during discography. However, the pressure differences appeared to rapidly increase in response to incremental increases in injection speed. The data from these 82 samples suggest that uncontrolled high speeds of intradiscal injections are a potential confounding factor, which may increase false-positive responses during lumbar discography.

Correlations between subjective treatment responses and plantar pressure parameters of metatarsal pad treatment in metatarsalgia patients: a prospective study

BackgroundMetatarsalgia is related to repetitive high-pressure loading under the metatarsal head (MH) that causes pain. The high pressure under the MH can be reduced by adequately applying metatarsal pads (MPs). Plantar pressure measurements may provide a method to objectively evaluate pressure loading under the MH. However, it is still unclear if the decrease in plantar pressure under the MH after MP treatment is associated with subjective improvement. This study aims to explore the correlations between subjective pain improvement and outcome rating, and the plantar pressure parameters in metatarsalgia patients treated using MPs.MethodsThirteen patients (a total of 18 feet) with secondary metatarsalgia were included in this study. Teardrop-shaped MPs made of polyurethane foam were applied just proximal to the second MH by an experienced physiatrist. Insole plantar pressure was measured under the second MH before and after MP application. Visual analog scale (VAS) scores of pain were obtained from all subjects before and after 2 weeks of MP treatment. The subjects rated using four-point subjective outcome scales. The Wilcoxon signed-rank test was used to analyze the difference between the plantar pressure parameters and VAS scores before and after treatment. The Kruskal-Wallis test was applied to compare the plantar pressure parameters in each outcome group. Pearson's correlation was applied to analyze the correlation between the changes in plantar pressure parameters and VAS scores. Statistical significance was set as p < 0.05.ResultsMP application decreased the maximal peak pressure (MPP) and pressure-time integral (PTI) under the second MH and also statistically improved subjective pain scores. However, neither the pre-treatment values of the MPP and PTI shift in the position of the MPP after treatment, nor the age, gender and body mass index (BMI) of the subjects were statistically correlated with subjective improvement. Declines in the PTI and MPP values after MP application were statistically correlated with the improvement in VAS scores (r = 0.77, R2 = 0.59, p < 0.001; r = 0.60, R2 = 0.36, p = 0.009).ConclusionWe found that the successful decline in the PTI and MPP under the second MH after MP application was correlated to subjective pain improvement. This study provides a strategy for the further design and application of MPs for metatarsalgia treatment.

The role of ricochet impacts on impact vaporization

Vaporization of carbonate targets by hypervelocity impact increases with decreasing impact angle (from the horizontal), in contrast with expectations based only on peak shock pressures. Experiments at the NASA Ames Vertical Gun Range were designed to allow isolating the underlying controlling processes and probing the vapor composition using high-speed spectroscopy. Vaporization associated with the maximum peak pressures (first contact) was separated from vaporization generated only by downrange ricochet impacts through the use of split targets. Four telescopes isolated the vapor with different velocities and revealed that grazing ricochet debris downrange contributed a significant fraction to the overall vaporization process. These results can be understood by the high temperatures and low pressures created by high strain-rate shear.

들기 작업에서 높이와 각도 변화가 발 부위에 미치는 스트레스에 관한 연구

In this paper, we propose a stress analysis on foot by lifting task attitudes. Maximum force and peak pressure were measured on 8 body regions by Pedar system in order to analysis the stress which is affected by task style and angle on foot when Manual Materials Handling task. As for the peak pressure of the whole foot as to the task height during the lifting task, the height from Knuckle to Shoulder was the least in the peak pressure. Also, as for the maximum force and the peak pressure of the whole foot as to the task angle during the lifting task, it could be seen that the more an angle increases, the stress influencing on a foot jumps. As for the maximum force and the peak pressure by foot region as to the task height in case of the lifting task, the height from Knuckle to Shoulder is indicated the smallest value in the maximum force and the peak pressure, thus there is necessary to attain the work design that considered this. Also, as for the maximum force by foot region as to the task angle in case of the lifting task, 0° tasking is indicated to be least, thus there is necessity to be attained the tasking design in a bid to prevent the existence of an angle. The results of this paper are thought to be helpful to the suitable work design, to the prevention of musculoskeletal disorders related to the lower limbs, and to the design of ergonomic safety shoes.

Study on combustion characteristics and PM emission of diesel engines using ester–ethanol–diesel blended fuels

In this study, one kind of vegetable methyl ester was added to ethanol–diesel fuel to prevent the separation of ethanol from diesel; thus the ethanol percentage can be up to 30% in volume. More attention was paid to its combustion characteristics, the effects of ethanol on particulate matter (PM) components, SOF (soluble organic fraction), DS (dry soot), and sulfate mass, using different fuel blends in the engine. To understand the effect of ethanol blended diesel fuels on combustion processes and soot formation, images of combustion processes were recorded using a high-speed CCD camera. The results show that with increasing ethanol in the blended fuel, both smoke and PM can be reduced, but the PM decrease is not as efficient as the smoke decrease. The smoke and PM behave differently even for one kind of fuel blend, and it is unreasonable to evaluate the PM emission by the smoke. In addition, under the same condition, increasing ethanol in the fuel blend, the DS emission in PM is reduced significantly, the sulfate emission hardly changes, and the SOF emission in PM is not reduced as expected. The results also indicate that addition of ethanol to diesel fuels the ignition is prolonged, maximum heat release ratio and peak pressure increase, and combustion duration is shortened. In addition, the flame luminosity in the combustion is decreased using blended fuels, which indicates that soot formation in fuel-rich regions is suppressed by the ethanol.