Belt Position Research Articles

Influence of different electrode belt positions on electrical impedance tomography imaging of regional ventilation: a prospective observational study.

BackgroundElectrical impedance tomography (EIT) is a non-invasive bedside tool which allows an individualized ventilator strategy by monitoring tidal ventilation and lung aeration. EIT can be performed at different cranio-caudal thoracic levels, but data are missing about the optimal belt position. The main goal of this prospective observational study was to evaluate the impact of different electrode layers on tidal impedance variation in relation to global volume changes in order to propose a proper belt position for EIT measurements.MethodsEIT measurements were performed in 15 mechanically ventilated intensive care patients with the electrode belt at different thoracic layers (L1-L7). All respiratory and hemodynamic parameters were recorded. Blood gas analyses were obtained once at the beginning of EIT examination. Off-line tidal impedance variation/tidal volume (TV/VT) ratio was calculated, and specific patterns of impedance distribution due to automatic and user-defined adjustment of the colour scale for EIT images were identified.ResultsTV/VT ratio is the highest at L1. It decreases in caudal direction. At L5, the decrease of TV/VT ratio is significant. We could identify patterns of diaphragmatic interference with ventilation-related impedance changes, which owing to the automatically adjusted colour scales are not obvious in the regularly displayed EIT images.ConclusionsThe clinical usability and plausibility of EIT measurements depend on proper belt position, proper impedance visualisation, correct analysis and data interpretation. When EIT is used to estimate global parameters like VT or changes in end-expiratory lung volume, the best electrode plane is between the 4th and 5th intercostal space. The specific colour coding occasionally suppresses user-relevant information, and manual rescaling of images is necessary to visualise this information.

Impact of grass belt position on the hydraulic properties of runoff in gully beds in the Yuanmou Dry-hot valley region of Southwest China

Gully erosion is one of the major contributors to severe land degradation in the Yuanmou Dry-hot valley region of Southwest China. Planting vegetation in gully beds has proven to be an effective measure in controlling the development of gullies. However, the inner mechanism for this process remains unclear. In this paper, in situ scouring experiments were performed to reveal the influence of grass belt position on the hydraulic properties of runoff in gully beds. The results demonstrate that (1) grass belt position can have a significant effect on reducing runoff erosivity (runoff shear stress, stream power) and sediment content in gully beds, and that the reduction may be strengthened as the distance between the gully headwall and grass belt (DHG) decreases; (2) grass belts could play a positive role in enhancing the surface resistance and increasing flow energy consumption, as resistance and flow energy consumption increase as DHG increases; and (3) there were similar trends in the temporal variations within the hydraulic properties, which changed sharply in the early stage of the experiment and then tended to stabilize, with their time to stability continuously increasing as DHG decreased.

Indoor magnetic signature based localization algorithm without person-dependent parameter calibration.

Location-dependent differences of ambient magnetic fields inside a building can be used to estimate location. In this paper, an inertial/magnetic sensor is attached to a belt position and its location is estimated using the ambient magnetic field. The walking distance is estimated using the linear relationship between the walking step length and the maximum acceleration during the step. The magnetic field data during walking is compared with a pre-collected magnetic signature. In this process, calibration steps are required for two person-dependent parameters : the walking step length estimation parameter and the hard iron parameter. An adaptive algorithm is proposed, in which these person-dependent parameters are estimated in addition to the location. Thus no person-dependent parameter calibration process is required. Through experiments, it is shown that the location and parameters are estimated accurately.

Development, Calibration, and Validation of a Head–Neck Complex of THOR Mod Kit Finite Element Model

Introduction/Objective: In an effort to continually improve upon the design of the test device for human occupant restraint (THOR) dummy, a series of modifications have recently been applied. The first objective of this study was to update the THOR head–neck finite element (FE) model to the specifications of the latest dummy modifications. The second objective was to develop and apply a new optimization-based methodology to calibrate the FE head–neck model based on experimental test data. The calibrated head–neck model was validated against both frontal and lateral impact test data. Finally, the sensitivities of the model, in terms of head and neck injury criteria, to pretest positioning conditions were evaluated in a frontal crash test simulation.Methods: The updated parts of the head–neck THOR FE model were remeshed from CAD geometries of the modified parts. In addition, further model modifications were made to improve the effectiveness of the model (e.g., model stability). A novel calibration methodology, which incorporates the CORA (CORelation and Analysis) rating system with an optimization algorithm implemented in Isight software, was developed to improve both kinematic and kinetic responses of the model in various THOR dummy certification and biomechanical response tests. A parametric study was performed to evaluate head and neck injury criteria values in the calibrated head–neck model during a 40 km/h frontal crash test with respect to variation in the THOR model upper body and belt pretest position.Results: Material parameter optimization was shown to greatly improve the updated model response by increasing the average rating score from 0.794 ± 0.073 to 0.964 ± 0.019. The calibrated neck showed the biggest improvement in the pendulum flexion simulation from 0.681 in the original model up to 0.96 in the calibrated model. The fully calibrated model proved to be effective at predicting dummy response in frontal and lateral loading conditions during the validation phase (0.942 average score). Upper body position was shown to have a greater effect on head–neck response than belt position. The pretest positioning variation resulted in a 10 percent maximum change in HIC36 values and 14 percent maximum change in NIJ values.Conclusion: The optimization-based calibration methodology was effective as it markedly improved model performance. The calibrated head–neck model demonstrated application in a crash safety analysis, showing slight head–neck injury sensitivity to pretest positioning in a frontal crash impact scenario.

Electrical impedance tomography during major open upper abdominal surgery: a pilot-study.

BackgroundElectrical impedance tomography (EIT) of the lungs facilitates visualization of ventilation distribution during mechanical ventilation. Its intraoperative use could provide the basis for individual optimization of ventilator settings, especially in patients at risk for ventilation-perfusion mismatch and impaired gas exchange, such as patients undergoing major open upper abdominal surgery. EIT throughout major open upper abdominal surgery could encounter difficulties in belt positioning and signal quality. Thus, we conducted a pilot-study and tested whether EIT is feasible in patients undergoing major open upper abdominal surgery.MethodsFollowing institutional review board’s approval and written informed consent, we included patients scheduled for major open upper abdominal surgery of at least 3 hours duration. EIT measurements were conducted prior to intubation, at the time of skin incision, then hourly during surgery until shortly prior to extubation and after extubation. Number of successful intraoperative EIT measurements and reasons for failures were documented. From the valid measurements, a functional EIT image of changes in tidal impedance was generated for every time point. Regions of interest were defined as horizontal halves of the picture. Monitoring of ventilation distribution was assessed using the center of ventilation index, and also using the total and dorsal ventilated lung area. All parameter values prior to and post intubation as well as extubation were compared. A p < 0.05 was considered statistically significant.ResultsA total of 120 intraoperative EIT measurements during major abdominal surgery lasting 4-13 hours were planned in 14 patients. The electrode belt was attached between the 2nd and 4th intercostal space. Consecutive valid measurements could be acquired in 13 patients (93%). 111 intraoperative measurements could be retrieved as planned (93%). Main obstacle was the contact of skin electrodes. Despite the high belt position, distribution of tidal volume showed a significant shift of ventilation towards ventral lung regions after intubation. This was reversed after weaning from mechanical ventilation.ConclusionsDespite a high belt position, monitoring of ventilation distribution is feasible in patients undergoing major open upper abdominal surgery lasting from 4 to 13 hours. Therefore, further interventional trials in order to optimize ventilatory management should be initiated.

Reservoir Characteristics of Buried Hill and Oil and Gas Distribution of Hailaer Basin - Case Study of Budate Formation of Sudeerte Oilfield

Buried hill reservoirs are typically found in Sudeerte oilfield in Hailaer basin. In this paper, the lithology, physical property and electric property of buried hill reservoirs are studied incorporating core data, mud logging, wireline logging and seismic attributes data. The major reservoir types of Budate buried hill are confirmed to include porosity, fracture, cavern and dissolved pore, which belong to dual porosity reservoirs. Vertically, the reservoirs get worse with the increase of buried depth and are controlled horizontally by weathering crust position and tectonic stress, and locations nearby fractured belt and structural high positions are preferable places for the formulation of good reservoirs. Oil and gas within the reservoir mainly accumulated inside fractures and pores and reservoirs with plenty existence of fractures and pores have good oil and gas shows and vice versa.

An Efficient and Robust Fall Detection System Using Wireless Gait Analysis Sensor with Artificial Neural Network (ANN) and Support Vector Machine (SVM) Algorithms

In this work, a total of 322 tests were taken on young volunteers by performing 10 different falls, 6 different Activities of Daily Living (ADL) and 7 Dynamic Gait Index (DGI) tests using a custom-designed Wireless Gait Analysis Sensor (WGAS). In order to perform automatic fall detection, we used Back Propagation Artificial Neural Network (BP-ANN) and Support Vector Machine (SVM) based on the 6 features extracted from the raw data. The WGAS, which includes a tri-axial accelerometer, 2 gyroscopes, and a MSP430 microcontroller, is worn by the subjects at either T4 (at back) or as a belt-clip in front of the waist during the various tests. The raw data is wirelessly transmitted from the WGAS to a near-by PC for real-time fall classification. The BP ANN is optimized by varying the training, testing and validation data sets and training the network with different learning schemes. SVM is optimized by using three different kernels and selecting the kernel for best classification rate. The overall accuracy of BP ANN is obtained as 98.20% with LM and RPROP training from the T4 data, while from the data taken at the belt, we achieved 98.70% with LM and SCG learning. The overall accuracy using SVM was 98.80% and 98.71% with RBF kernel from the T4 and belt position data, respectively.

Kinematics and Shoulder Belt Position of Child Anthropomorphic Test Devices During Steering Maneuvers

Objectives: The objective of this study was to quantify and compare the kinematics and shoulder belt position of child anthropomorphic test devices (ATDs) during emergency steering maneuvers. Furthermore, the ATDs were compared to the results from child volunteers aged 4 to 12 in the same test setup (Bohman, Stockman, et al. 2011). Methods: A driving study was conducted on a test track comprising 4 ATDs: the Q6, Q10, and Hybrid III (HIII) 6- and 10-year-old ATDs restrained in the rear seat of a passenger vehicle. The ATDs were exposed to 2 repeated steering maneuvers in each restraint system. The Q6 and HIII 6-year-old were restrained on booster cushions as well as high-back booster seats. The Q10 and HIII 10-year-old were restrained on booster cushions or restrained by 3-point seat belts directly on the seat. Lateral motion of the forehead and upper sternum was determined, as well as shoulder belt movement on shoulder and torso tilting angle. Results: All ATDs began to move approximately at the same point in time corresponding to a vehicle lateral acceleration of just below 0.2 g. In the later phase of the maneuver, Q10 had moved 26 percent less than the children when restrained by seat belt only and 35 percent less when on a booster cushion. Corresponding numbers for the HIII 10-year-old were 43 and 44 percent higher than for children. Compared to children, the Q6 had moved 34 percent less when restrained on a high-back booster seat and 31 percent less when on a booster cushion. Corresponding numbers for HIII 6-year-old were 7 and 28 percent higher than for children. Due to extensive variety of lateral displacements observed in the children, child performance range covers both ATD families for the evaluated sizes of 6- and 10-year-old ATDs. Conclusions: Compared to children, the HIII ATDs were closer with regards to mean values in the initial phase of the maneuver and the Q ATDs were closer in the end of the ramping phase of the lateral acceleration. The question regarding which ATD replicates better the behavior of children exposed to steering maneuvers still remains open. As shown in this study, it depends on the focus of the comparison and on what phase of the maneuver is of interest. This study provides valuable knowledge on how representative the current ATDs are for replicating potential precrash postures of children as a result of vehicle emergency steering maneuvers for a variety of restraint systems and ATD sizes.

FORECASTING A CORONAL MASS EJECTION'S ALTERED TRAJECTORY: ForeCAT

To predict whether a coronal mass ejection (CME) will impact Earth, the effects of the background on the CME's trajectory must be taken into account. We develop a model, ForeCAT (Forecasting a CME's Altered Trajectory), of CME deflection due to magnetic forces. ForeCAT includes CME expansion, a three-part propagation model, and the effects of drag on the CME's deflection. Given the background solar wind conditions, the launch site of the CME, and the properties of the CME (mass, final propagation speed, initial radius, and initial magnetic strength), ForeCAT predicts the deflection of the CME. Two different magnetic backgrounds are considered: a scaled background based on type II radio burst profiles and a Potential Field Source Surface (PFSS) background. For a scaled background where the CME is launched from an active region located between a CH and streamer region the strong magnetic gradients cause a deflection of 8.1 degrees in latitude and 26.4 degrees in longitude for a 1e15 g CME propagating out to 1 AU. Using the PFSS background, which captures the variation of the streamer belt position with height, leads to a deflection of 1.6 degrees in latitude and 4.1 degrees in longitude for the control case. Varying the CME's input parameters within observed ranges leads to the majority of CMEs reaching the streamer belt within the first few solar radii. For these specific backgrounds, the streamer belt acts like a potential well that forces the CME into an equilibrium angular position.

Links between the plasmapause and the radiation belt boundaries as observed by the instruments CIS, RAPID, and WHISPER onboard Cluster

In the present work, we study the relations between the position of the plasmapause and the position of the radiation belt boundaries. The Cluster mission offers the exceptional opportunity to analyze those different regions of the inner magnetosphere with identical sensors on multiple spacecraft. We compare the positions of the radiation belt edges deduced from CIS (Cluster Ion Spectrometry) observations (electrons with energy &gt;2 MeV) with the positions of the plasmapause derived from WHISPER (Waves of HIgh frequency and Sounder for Probing of the Electron density by Relaxation) data (electron plasma frequency). In addition, we compare those results with the edges positions determined from RAPID (Research with Adaptive Particle Imaging Detectors) observations (electrons with energy between 244.1 and 406.5keV). The period of 1 April 2007 to 31 March 2009 has been chosen for the analysis because at that time Cluster's perigee was located at lower radial distances than during the earlier part of the mission. The perigee was then as close as 2 RE, deep inside the plasmasphere and the radiation belts. This time period corresponds to a long solar activity minimum. Differences are observed between the radiation belt boundary positions obtained from the two different instruments: The radiation belt positions are related to the energy bands. The results show that the plasmapause position is more variable than the radiation belt boundary positions, especially during small geomagnetic activity enhancements. A correspondence is observed between the plasmapause position determined by WHISPER and the outer edge of the outer radiation belt of energetic electrons (&gt;2 MeV) observed by CIS. This result is unexpected since previous studies based on other spacecraft observations indicated a correlation between the inner edge of the outer belt and the plasmapause. However, during higher geomagnetic activity time periods, the plasmapause is located closer to the inner boundary of the outer radiation belt. Also, the thickness of the slot region is found to follow the global evolution of the geomagnetic activity.

Robust Design in Occupant Safety Simulation

Explicit FE-simulation has become a standard design tool in passive safety development as it can help to reduce the number of vehicle prototype tests, especially in the early project stages. Due to fewer hardware tests available as sources of validation, the expectations towards predictability of dummy injury occurrence have strongly increased. To produce robust results, virtual passive safety analysis has to take real uncertainties of test condition and their probabilistic effects upon the system's response into account. FINDINGS by simulation therefore should not be regarded anymore as single point statements in a pure deterministic approach. They rather need to be extended into statements upon grades of correlation between individual system parameters taking into account their stochastic nature. This paper illustrates a process for complete robustness analysis in occupant safety simulation. It introduces techniques to document statistical confidence intervals of the correlations determined, and uses statistical bootstrapping in populations where only a limited number of samplings can be generated. Finally, by regression analysis within the reduced relevant physical parameter space, a risk assessment upon a potential failure within the specific test requirements is carried out. Identification of initial design space parameters requires experience and proper preparation when one is conducting statistical analysis on occupant safety. This work explains relevant design space parameters for a typical full vehicle test and classifies them in proper ways since obtaining their sampling often requires additional pre-simulation efforts. In this context a number of in-house tools are highlighted here that helps the designer in obtaining work intensive design parameters such as the distribution of dummy, seat & belt positions. The entire robustness design process uses automated work flows and tools to visualize the statistical data observed since the simulation model complexity and its computational costs are extremely high. Finally, the gained correlations are discussed, interpreted and explained in terms of real life phenomenon that can be observed in testing. Language: en

Validity and Reliability of Measuring Steps and Energy Expenditure with a Triaxial Accelerometer in Healthy Adults under Controlled Conditions

Purpose: To determine the validity and test-retest reliability of a triaxial accelerometer in measuring steps and estimating energy expenditure in healthy adults. Method: 20 volunteers walked 3 times for 10 minutes on a treadmill following a standardized protocol. Data of the accelerometer were compared to hand tally counted steps and to breath by breath analysis of respiratory variables. Bland-Altman plots and an intra-class correlation coefficients were used to determine validity and reliability. Results: Accelerometers generated valid results at 5km/h but not at 3km/h. At 5 km/h the lanyard and belt positions were more valid than the pocket positions. The test-retest reliability was good to excellent for steps (ICC range .78 - .92) and moderate to good for energy expenditure (ICC range .64 - .87). Conclusions: The accelerometer generated valid results for the number of steps at 5 km/h with a coefficient of variation of 1-1.6% but overestimated energy expenditure.

Kinematics of Child Volunteers and Child Anthropomorphic Test Devices During Emergency Braking Events in Real Car Environment

Objectives: The objective of this study was to present, compare, and discuss the kinematic response of children and child anthropomorphic test devices (ATDs) during emergency braking events in different restraint configurations in a passenger vehicle. Methods: A driving study was conducted on a closed-circuit test track comprising 16 children aged 4 to 12 years old and the Q3, Hybrid III (HIII) 3-year-old, 6-year-old, and 10-year-old ATDs restrained on the right rear seat of a modern passenger vehicle. The children were exposed to one braking event in each of the 2 restraint systems and the ATDs were exposed to 2 braking events in each restraint system. All events had a deceleration of 1.0 g. Short children (stature 107–123 cm) and the Q3, HIII 3-year-old, and 6-year-old were restrained on booster cushions as well as high-back booster seats. Tall children (stature 135–150 cm) and HIII 10-year-old were restrained on booster cushions or restrained by 3-point belts directly on the car seat. Vehicle data were collected and synchronized with video data. Forward trajectories for the forehead and external auditory canal (ear) were determined as well as head rotation and shoulder belt force. Results: A total of 40 trials were analyzed. Child volunteers had greater maximum forward displacement of the head and greater head rotation compared to the ATDs. The average maximum displacement for children ranged from 165 to 210 mm and 155 to 195 mm for the forehead and ear target, respectively. Corresponding values for the ATDs were 55 to 165 mm and 50 to 160 mm. The change in head angle was greater for short children than for tall children. Shoulder belt force was within the same range for short children when restrained on booster cushions or high-back booster seats. For tall children, the shoulder belt force was greater when restrained on booster cushions compared to being restrained by seat belts directly on the car seat. Conclusions: The forward displacement was within the same range for all children regardless of stature and restraint system. However, the maximum forward position depended on the initial seated posture and shoulder belt position on the shoulder. Differences could also be seen in the curvature of the neck and spine. Short children exhibited a greater flexion motion of the head, whereas a more upright posture at maximum forward position was exhibited by the tall children. The ATDs displayed less forward displacement compared to the children. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

Evaluation of the Head Kinematics of the Q3 Model and a Modified Q3 Model by Means of Crash Reconstruction

Objective: One objective of this study is to evaluate the head kinematics of the Q3 model. Another objective is to evaluate the effect on head kinematics of increased thoracic spine flexibility; more humanlike mass distribution; and more humanlike body geometry in the Q3 model. The evaluations were based on the head kinematics of children deduced from real crashes and on new data of mass distribution and updated body dimensions for 3-year-olds. Methods: The head kinematics of the Q3 model was evaluated by comparing the Q3 model's head displacement response with the deduced response of 3-year-old children in real crashes. To do so, data from crashes were collected. The data were used to develop the mathematical vehicle and restraint system models (MADYMO, TASS, the Netherlands). Three crashes involving 3-year-old children in frontal impacts were reconstructed. The models were run 35 times each (one model per crash), each time with a different setting to each of the variables for which the exact value was not known. Examples of those variables include crash pulse, initial dummy position, and initial seat belt position. Two versions of the Q3 model were used: one that correlated with the Q3 ATD and one that was modified regarding anthropometry and thoracic flexibility. The basis for the updated anthropometry was new data regarding characteristic dimensions and mass distribution collected at a Swedish hospital. Results: In the anthropometry study, 26 children were measured. The main differences between the average of the measured children and the Q3 model were found in the mass distribution of the torso and thighs: the Q3's pelvis was too heavy and the thorax, abdomen/lumbar spine, and thighs were too light. Another difference was identified in the buttock–knee length. Two of the 3 reconstructed crashes had confirmed head impacts. The Q3 model responded with head kinematics that reflected the deduced courses of events for the real children in one of 3 crashes (the one without head impact). The modified Q3 model reflected the real children in 2 of 3 crashes. Conclusions: In high-severity, straight frontal crashes, the Q3 model predicted non-head impact adequately. However, in oblique frontal crashes, the Q3 model did not sufficiently predict the head impacts. The modified Q3 model predicted the head impacts better than the Q3 model did. Greater flexibility of the thorax and redistributed mass made a positive difference regarding the head kinematics.

Improved Ink Registration through Advanced Steel Belt Steering

Manufacturing equipment for single-pass digital printing faces an interesting challenge to deal with the growing productivity demand in combination with rising droplet registration accuracy. Although the administration speed of printheads is still rising, high throughput speeds and/or increased print resolution can only be achieved by using multiple heads in series. Given at least 4 different inks, the distance between the first and last print-head can become more that a meter. When the relative registration accuracy over such a distance must be less than 10 micrometer, an intense fusion of multiple engineering disciplines becomes essential. In order to eliminate the mechanical (e.g. elasticity) properties of the substrate, a steel belt conveyer using vacuum technology for substrate clamping is introduced. Many conventional steel belt conveyors and their steering systems can't meet the previously mentioned accuracy target. By introducing actuated Axially Movable Segments Rolls (AMSR), the 2 surface orientations (X, Rz) of the belt (and therefore the substrate) can be continuously controlled, without deformation of the belt. On both sides of the rolls there are reluctance force actuators for segment manipulation. During rotation, the belt (always) will translate axially with respect to the segments that are in contact due to given limitations in belt and/or roll manufacturing (e.g. accuracy of the weld perpendicularity). The actuated AMSRs compensate this translation, based on the measured belt position. Once per revolution, when the segment is not in contact with the steel-belt, it will be actively positioned back to its &#x2018;center&#x2019; position to minimize disturbances in the system. A demonstrator has been build to validate the actuated AMSR technology.

Driver Report of Improper Seat Belt Position Among 4- to 9-Year-old Children

Objective To determine the frequency with which drivers report improper seat belt positions among children 4–9 years of age and the frequency with which reported problems were attributable to the lap belt, shoulder belt, or both. Subjects and Methods Analysis of driver responses to 5 questions related to seat belt positioning from the cross-sectional, phone-based 2007 Motor Vehicle Occupant Safety Survey. Belt position problems categorized as related to (1) shoulder belt and (2) lap belt. Improper belt position was compared across age groups (4–6 years, 7–8 years, and 9 years) and use of a child safety seat with χ 2 statistics or Fisher exact tests as appropriate. Results Seat belt use was reported for 334 of 891 (37%) 4- to 9-year-old child passengers, and 261 (78%) drivers reported improper belt fit among these child passengers. Improper shoulder belt position (44%) was less common than improper lap belt position (62%). At least one improper belt position was reported by 78% of drivers of 4- to 6-year-old children, 77% of 7- to 8-year-old children, and 79% of 9-year-old children ( P = .87). There were no significant differences in report of improper belt position among children who never and those who occasionally use a child safety seat were compared. Conclusions Drivers frequently report improper lap and shoulder belt positions for their 4- to 9-year-old child passengers yet persist in restraining children by the use of seat belts alone. Clinicians can promote the use of size-appropriate child passenger restraint systems, including car seats and booster seats, to overcome the improper belt positions identified in this study.

Variations in Rear Seat Cushion Properties and the Effects on Submarining

Objective: This study aims to investigate the effects of seating posture and seat cushion properties on submarining risk for rear seated children. Methods: An instrumented 6-year-old Hybrid III dummy restrained by an inertial-reel 3-point seat belt was subjected to simulated frontal impacts (Δv = 28.8 km/h, peak acceleration = 16 g). Dummy motion was captured using high-speed digital video. Head acceleration, neck loads, chest deflection, pelvic rotation, and femur displacement were used to assess submarining. Factors investigated included pre-impact seating posture, seat cushion length, stiffness of the seat cushion foam, and the inclination of the seat cushion. Results: The most severe submarining was observed when the dummy was seated in a slouched posture where pelvic rotation was over 3 times greater than in the upright seating posture. Though the standard seat cushion with the dummy seated in the upright posture recorded the lowest values of pelvic rotation and femur displacement, it is unlikely that a child will sit in such a posture. The shortened seat cushion increased femur displacement by 19 percent compared to the standard test seat, but it offers good pre-impact belt position. Submarining occurred in cases where the front edge of the seat collapsed during interactions with the dummy's buttocks. Conclusions: These data suggest that shortening the rear seat cushion alone will not necessarily prevent submarining, but this does allow improved seated posture of the occupant, thus reducing submarining risk. This study has also shown that the collapse of the front edge of the seat cushion is a critical factor in submarining risk.

Commentary

Commentary

A New Family of Sandwich-Type Polytungstophosphates Containing Two Types of Metals in the Central Belt: M′2M2(PW9O34)212−(M′ = Na or Li, M = Mn2+, Co2+, Ni2+, and Zn2+)

A new family of sandwich-type polytungstophosphates containing two different types of metals in the central belt, M'(2)M(2)(PW(9)O(34))(2)(12-) (M' = Na or Li, M = Mn(2+), Co(2+), Ni(2+), and Zn(2+)), have been synthesized and characterized by infrared spectroscopy, (31)P solution NMR spectroscopy, and elemental analysis. Compounds Na(2)Co(2)(PW(9)O(34))(2)(12-) (Na2Co2), Na(2)Ni(2)(PW(9)O(34))(2)(12-) (Na2Ni2), Li(2)Ni(2)(PW(9)O(34))(2)(12-) (Li2Ni2), Na(2)Mn(2)(PW(9)O(34))(2)(12-) (Na2Mn2), and Li(2)Zn(2)(PW(9)O(34))(2)(12-) (Li2Zn2) were characterized by X-ray crystallography. All these compounds have similar structures, in which two transition-metal ions and two alkali metal ions (sodium or lithium) are sandwiched between two [B-alpha-PW(9)O(34)](9-) units; the transition and alkali metals reside in the internal and external (solvent exposed) positions of the central belt, respectively. By adding LiCl to aqueous solutions of compounds Na2M2, lithium-sodium exchanges in the external belt positions are observed by (31)P solution NMR spectroscopy and X-ray crystallography. Magnetic measurements indicate ferromagnetic exchange interactions between the two Ni(2+) ions in Na2Ni2 at 10-300 K and the two Co(2+) ions in Na2Co2 at 6-30 K. In contrast, Na2Mn2 exhibits an antiferromagnetic interaction between the Mn(2+) ions at 2-50 K.

Assembly of titanium embedded polyoxometalates with unprecedented structural features

Two titanium embedded polyoxometalates with unprecedented structural features are presented: a monotitanium containing tungstoantimonate Na(13)H(3)[TiO(SbW(9)O(33))(2)]·33 H(2)O featuring a {Ti=O}(2+) moiety (1) and a hexatitanium containing tungstoarsenate K(6)[Ti(4)(H(2)O)(10)(AsTiW(8)O(33))(2)]·30 H(2)O containing a {Ti(4)(H(2)O)(10)}(16+) moiety (2). Both compounds have been fully characterised by single crystal X-ray diffraction, elemental analysis, IR and TGA. 1 is constructed from two α-B-{Sb(III)W(9)O(33)} fragments linked by five sodium cations and an unprecedented square pyramidal Ti(O)O(4) group with a terminal Ti=O bond, and 2 exhibits a Krebs-type structure composed of two {AsTiW(8)O(33)} fragments, where one W(VI) centre has been substituted for a Ti(IV) centre in each, fused together via a belt of four additional Ti(IV) centres. This system represents the tungsten Ti-incorporated polyoxoanion with one of the highest Ti:W ratios so far reported. Additionally, 2 could also be isolated as an n-tetrabutylammonium salt and has been further characterised by electrochemistry and electrospray ionisation (ESI) MS studies. Due to the unique nature of these systems, both have been fully investigated using DFT calculations yielding highly interesting results. Structure 1 has been optimised with five sodium atoms in the belt position, which in addition to reducing the high charge of the cluster influence a stabilisation of the antimony lone pairs. Electrostatic potential calculations highlight the high electronegativity of the terminal oxygen on the titanium centre, enhancing real potentiality as a reactive site for catalysis.