Compartment Thickness Research Articles

Reliability of Ultrasound Based Compressibility of the Lower Leg Anterior Tibial Muscle Compartment in Healthy Volunteers.

Some individuals have exercise-induced lower leg pain (ELP) caused by a chronic exertional compartment syndrome (CECS). As intracompartmental muscle pressure measurements are invasive with suboptimal test characteristics, other diagnostic tools are needed. Recently, ultrasound-based muscle compartment thickness analysis at 10mmHg (d10) and 80mmHg (d80) external pressure was introduced for this purpose. The difference in compartment thickness at these two external pressures induced by the study device is used to calculate muscle compressibility, a possible marker for CECS. The purpose of this study was to investigate the reliability of a novel ultrasound compressibility technique using two distinct internal landmarks at the lower leg in a diverse group of asymptomatic adults. Cross-sectional study. Healthy volunteers (n=35; 21 female; median age 40 years, range 19-72; BMI 24.1 kg/m2, range 18.3-31.6) not having ELP underwent serial compressibility measurements (n=1678) of both legs by three observers at the tibialis anterior (TA) using the interosseous membrane (IM) and transition zone IM to tibial bone (TZIT) as internal landmarks. Inter- and intra-observer reliability was calculated for values of d10, d80 and compressibility using intraclass correlations (ICC). TA compartments are less compressible using the IM landmark compared to the TZIT landmark (10.5% vs 12.5%; p<0.001). Inter-observer ICC for IM was always higher (d10 0.85; d80 0.82; compressibility 0.51) than for TZIT (d10 0.65; d80 0.53; compressibility 0.20). The intra-observer reliability for d10 and d80 was excellent (ICC>0.90) for all three observers. ICC of compressibility varied among observers and ranged from 0.76 to 0.48, with higher ICCs demonstrated for IM compared to TZIT. Ultrasound based anterior tibial muscle compressibility measurements have moderate inter-observer reliability and excellent intra-observer reliability if the interosseous membrane is used as internal landmark. Future studies are aimed to test muscle compressibility after exercise and in CECS. Level 3.

Ultrasound guided compressibility of the lower leg anterior tibial muscle compartment: a feasibility study

ABSTRACT Objectives Some young individuals participating in sports activities may encounter lower leg muscle pain and tightness, potentially indicating chronic exertional compartment syndrome (CECS). While muscle pressure measurement is typically recommended for diagnosis, it is invasive and associated with low sensitivity and specificity. Thus, there is a need for novel diagnostic approaches. Methods This feasibility study aims to assess whether an ultrasound-guided technique can effectively measure the compressibility of the anterior tibial muscle compartment, focusing on optimal leg positioning and identifying reliable external and internal anatomical landmarks. The compressibility of the anterior tibial muscle compartment was evaluated using ultrasound images obtained at 10 mmHg and 80 mmHg external pressure, with the drop in compartment thickness used to calculate the compressibility ratio. Measurements were conducted in various leg positions and utilizing different external and internal landmarks. Results Studies in healthy volunteers showed that knee and heel support positioning, measuring at the leg’s widest circumference, and using the interosseous membrane as an internal landmark yielded the lowest measurement variability with an intra class correlation of .977 (.764–1.000; 95%-confidence interval). Conclusion These findings suggest that ultrasound-guided techniques can feasibly determine the compressibility ratio of the anterior tibial muscle compartment, providing valuable insights for standardized protocols in future studies on suspected cases of chronic exertional compartment syndrome.

Deep utilization of salinity gradient energy between concentrated seawater and river water by multi-stage reverse electrodialysis

While concentrated seawater discharged by desalination plants requires considerable efforts to alleviate undesired environmental risk, the conversion of salinity gradient energy to electric energy is considered an ideal way. In this work, the experiment and simulation of multi-stage reverse electrodialysis (MS-RED) were carried out, and the influence of flow rate and compartment thickness of high concentration compartment (HCC) and low concentration compartment (LCC) on the MS-RED performance were investigated independently for the huge concentration difference between HCC and LCC. The optimized flow rates of LCC and HCC were 0.96 cm·s−1 and 0.71 cm·s−1, and the compartment thicknesses of LCC and HCC were 1.05 mm and 0.85 mm, respectively. Furthermore, the performance of series multi-stage reverse electrodialysis (SMS-RED) and independent multi-stage reverse electrodialysis (IMS-RED) was compared, and SMS-RED showed better performance than IMS-RED. With the optimized conditions of SMS-RED, the power generation and energy efficiency were reached 684.07 W and 16.22 % after 20 stages, respectively, while the concentration of concentrated seawater was reduce from 66.70 to 37.63 g·L−1. The results can provide a theoretical basis for the industrial development of MS-RED to achieve the deep utilization of concentrated seawater and reduce the environmental risks of its direct discharge.

Retinal nerve fiber and ganglion cell complex layer thicknesses mirror brain atrophy in patients with relapsing-remitting multiple sclerosis.

Multiple sclerosis (MS) is associated with progressive brain atrophy, which in turn correlates with disability, depression, and cognitive impairment. Relapsing-remitting multiple sclerosis (RRMS) is a type of MS in which relapses of the disease are followed by remission periods. This is the most common type of the disease. There is a significant need for easy and low-cost methods to these cerebral changes. Changes in retinal layer thickness may reflect alterations in brain white and gray matter volumes. Therefore, this paper aims to determine whether retinal layer thickness, measured using optical coherence tomography (OCT), correlates with volumetric brain assessments obtained by magnetic resonance imaging (MRI). This retrospective cohort study recruited 53 patients with relapsing-remitting MS who underwent MRI and OCT examinations for evaluation of brain compartment volumes and thickness of retinal layers, respectively. OCT parameters, including central retinal thickness; retinal nerve fiber layer thickness (RNFL, peripapillary thickness); ganglion cell complex thickness (GCC, macular thickness); and Expanded Disability Status Scale (EDSS) results were compared with MRI parameters (cerebral cortex; cerebral cortex and basal ganglia combined; brain hemispheres without the ventricular system; and white matter plaques). We also checked whether there is a correlation between the number of RRMS and OCT parameters. Our primary objective was to identify whether these patients had retinal thickness changes, and our secondary objective was to check if those changes correlated with the MRI brain anatomical changes. RNFL and GCC thicknesses were strongly (p-value < 0.05) associated with (i) cerebral cortex volume, (ii) combination of brain cortex and basal ganglia volumes, and (iii) the hemispheres but without the ventricular system. White matter plaques (combined) showed only weak or no correlation with RNFL and GCC. There was no correlation between central retinal thickness and brain compartment volumes, and there were weak or no correlations between the summary EDSS scores and OCT results. Retinal layer thickness measured by OCT correlates with select volumetric brain assessments on MRI. During the course of RRMS, the anatomo-pathological structure of the retina might serve as a surrogate marker of brain atrophy and clinical progression within selected domains.

Risk Classification for Progression to Subfoveal Geographic Atrophy in Dry Age-Related Macular Degeneration Using Machine Learning-Enabled Outer Retinal Feature Extraction.

To evaluate the utility of spectral-domain optical coherence tomography biomarkers to predict the development of subfoveal geographic atrophy (sfGA). This was a retrospective cohort analysis including 137 individuals with dry age-related macular degeneration without sfGA with 5 years of follow-up. Multiple spectral-domain optical coherence tomography quantitative metrics were generated, including ellipsoid zone (EZ) integrity and subretinal pigment epithelium (sub-RPE) compartment features. Reduced mean EZ-RPE central subfield thickness and increased sub-RPE compartment thickness were significantly different between sfGA convertors and nonconvertors at baseline in both 2-year and 5-year sfGA risk assessment. Longitudinal change assessment showed a significantly higher degradation of EZ integrity in sfGA convertors. The predictive performance of a machine learning classification model based on 5-year and 2-year risk conversion to sfGA demonstrated an area under the receiver operating characteristic curve of 0.92 ± 0.06 and 0.96 ± 0.04, respectively. Quantitative outer retinal and sub-RPE feature assessment using a machine learning-enabled retinal segmentation platform provides multiple parameters that are associated with progression to sfGA. [Ophthalmic Surg Lasers Imaging. 2022;53:31-39.].

Anterolateral thigh measurements by ultrasound in neonates and young infants to ensure safe intramuscular injections during vaccination in low- and middle-income countries.

Use of same length needle for intramuscularly administered vaccines had been reported to cause under-and over-penetration among infants due to their different body weights and underlying variations in the fat and muscle thickness. Normative data regarding thigh compartment thickness are, however, lacking among neonates and infants aged ≤12 weeks particularly in low- and middle-incoming countries with high burden of low birth weight/growth restricted infants. Present study investigated skin to muscle and skin to bone (STBD) distances of anterolateral thigh of babies (n = 300) aged ≤12 weeks (1-80 days) with different weight groups (<3 kg, 3-4 kg and >4 kg) by ultrasonography during their intramuscular vaccinations. Overall, mean [standard deviation (SD)] STBD was 17.04 (2.66) mm with range of 10.60-23.30 mm. Stratifying by current body weight, mean (SD) STBD in infants weighing less than 3 kg was 14.39 (1.23) mm. For infants weighing between 3-4 kg and >4 kg, the mean (SD) STBD were 16.69 (1.43) mm and 17.04 (2.66) mm, respectively. Estimated safety (no risk of over-penetration) of 16 mm was observed in 57.33% (172) infants whereas 25 mm needle had 100% over-penetration risk in the study cohort. Current body weight of infants was a significant predictor of safe injection [area under the receiver operating characteristic (ROC) curve 0.95; 95% CI 0.92-0.97]. Our study offers objective normative measurements of anterolateral thigh for safe intramuscular vaccination in young infants especially for low birth weight and growth restricted infants in low- and middle-income countries.

Improved co-registration of ex-vivo and in-vivo cardiovascular magnetic resonance images using heart-specific flexible 3D printed acrylic scaffold combined with non-rigid registration

BackgroundEx-vivo cardiovascular magnetic resonance (CMR) imaging has played an important role in the validation of in-vivo CMR characterization of pathological processes. However, comparison between in-vivo and ex-vivo imaging remains challenging due to shape changes occurring between the two states, which may be non-uniform across the diseased heart. A novel two-step process to facilitate registration between ex-vivo and in-vivo CMR was developed and evaluated in a porcine model of chronic myocardial infarction (MI).MethodsSeven weeks after ischemia-reperfusion MI, 12 swine underwent in-vivo CMR imaging with late gadolinium enhancement followed by ex-vivo CMR 1 week later. Five animals comprised the control group, in which ex-vivo imaging was undertaken without any support in the LV cavity, 7 animals comprised the experimental group, in which a two-step registration optimization process was undertaken. The first step involved a heart specific flexible 3D printed scaffold generated from in-vivo CMR, which was used to maintain left ventricular (LV) shape during ex-vivo imaging. In the second step, a non-rigid co-registration algorithm was applied to align in-vivo and ex-vivo data. Tissue dimension changes between in-vivo and ex-vivo imaging were compared between the experimental and control group. In the experimental group, tissue compartment volumes and thickness were compared between in-vivo and ex-vivo data before and after non-rigid registration. The effectiveness of the alignment was assessed quantitatively using the DICE similarity coefficient.ResultsLV cavity volume changed more in the control group (ratio of cavity volume between ex-vivo and in-vivo imaging in control and experimental group 0.14 vs 0.56, p < 0.0001) and there was a significantly greater change in the short axis dimensions in the control group (ratio of short axis dimensions in control and experimental group 0.38 vs 0.79, p < 0.001). In the experimental group, prior to non-rigid co-registration the LV cavity contracted isotropically in the ex-vivo condition by less than 20% in each dimension. There was a significant proportional change in tissue thickness in the healthy myocardium (change = 29 ± 21%), but not in dense scar (change = − 2 ± 2%, p = 0.034). Following the non-rigid co-registration step of the process, the DICE similarity coefficients for the myocardium, LV cavity and scar were 0.93 (±0.02), 0.89 (±0.01) and 0.77 (±0.07) respectively and the myocardial tissue and LV cavity volumes had a ratio of 1.03 and 1.00 respectively.ConclusionsThe pattern of the morphological changes seen between the in-vivo and the ex-vivo LV differs between scar and healthy myocardium. A 3D printed flexible scaffold based on the in-vivo shape of the LV cavity is an effective strategy to minimize morphological changes in the ex-vivo LV. The subsequent non-rigid registration step further improved the co-registration and local comparison between in-vivo and ex-vivo data.

The Breathing Cell: Cyclic Intermembrane Distance Variation in Reverse Electrodialysis.

The breathing cell is a new concept design that operates a reverse electrodialysis stack by varying in time the intermembrane distance. Reverse electrodialysis is used to harvest salinity gradient energy; a rather unknown renewable energy source from controlled mixing of river water and seawater. Traditionally, both river water and seawater compartments have a fixed intermembrane distance. Especially the river water compartment thickness contributes to a large extent to the resistance of the stack due to its low conductivity. In our cyclic approach, two stages define the principle of the breathing concept; the initial stage, where both compartments (seawater and river water) have the same thickness and the compressed stage, where river water compartments are compressed by expanding the seawater compartments. This movement at a tunable frequency allows reducing stack resistance by decreasing the thickness of the river water compartment without increasing permanently the pumping losses. The breathing stacks clearly benefit from the lower resistance values and low pumping power required, obtaining high net power densities over a much broader flow rate range. The high frequency breathing stack (15 cycles/min) shows a maximum net power density of 1.3 W/m2. Although the maximum gross and net power density ever registered (2.9 W/m2 and 1.5 W/m2, respectively) is achieved for a fixed 120 μm intermembrane distance stack (without movement of the membranes), it is only obtained at a very narrow flow rate range due to the high pressure drops at small intermembrane distance. The breathing cell concept offers a unique feature, namely physical movement of the membranes, and thus the ability to adapt to the operational conditions and water quality.

Are lateral compartment osteophytes a predictor for lateral cartilage damage in varus osteoarthritic knees?: Data from the Osteoarthritis Initiative.

We studied whether the presence of lateral osteophytes on plain radiographs was a predictor for the quality of cartilage in the lateral compartment of patients with varus osteoarthritic of the knee (Kellgren and Lawrence grade 2 to 3). The baseline MRIs of 344 patients from the Osteoarthritis Initiative (OAI) who had varus osteoarthritis (OA) of the knee on hip-knee-ankle radiographs were reviewed. Patients were categorised using the Osteoarthritis Research Society International (OARSI) osteophyte grading system into 174 patients with grade 0 (no osteophytes), 128 grade 1 (mild osteophytes), 28 grade 2 (moderate osteophytes) and 14 grade 3 (severe osteophytes) in the lateral compartment (tibia). All patients had Kellgren and Lawrence grade 2 or 3 arthritis of the medial compartment. The thickness and volume of the lateral cartilage and the percentage of full-thickness cartilage defects in the lateral compartment was analysed. There was no difference in the cartilage thickness or cartilage volume between knees with osteophyte grades 0 to 3. The percentage of full-thickness cartilage defects on the tibial side increased from < 2% for grade 0 and 1 to 10% for grade 3. The lateral compartment cartilage volume and thickness is not influenced by the presence of lateral compartment osteophytes in patients with varus OA of the knee. Large lateral compartment osteophytes (grade 3) increase the likelihood of full-thickness cartilage defects in the lateral compartment.

Brief Report: Cartilage Thickness Change as an Imaging Biomarker of Knee Osteoarthritis Progression: Data From the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium.

To investigate the association of cartilage thickness change over 24 months, as determined by magnetic resonance imaging (MRI), with knee osteoarthritis (OA) progression at 24-48 months. This nested case-control study included 600 knees with a baseline Kellgren/Lawrence (K/L) grade of 1-3 from 600 Osteoarthritis Initiative (OAI) participants. Case knees (n = 194) had both medial tibiofemoral radiographic joint space loss (≥0.7 mm) and a persistent increase in the Western Ontario and McMaster Universities Osteoarthritis Index pain score (≥9 on a 0-100 scale) 24-48 months from baseline. Control knees (n = 406) included 200 with neither radiographic nor pain progression, 103 with radiographic progression only, and 103 with pain progression only. Medial and lateral femorotibial cartilage was segmented from sagittal 3T MRIs at baseline, 12 months, and 24 months. Logistic regression was used to assess the association of change in cartilage thickness, with a focus on the central medial femorotibial compartment, and OA progression. Central medial femorotibial compartment thickness loss was significantly associated with case status, with an odds ratio (OR) of 1.9 (95% confidence interval [95% CI] 1.6-2.3) (P < 0.0001). Association with case status reached P < 0.05 for both the central femur (OR 1.8 [95% CI 1.5-2.2]) and the central tibia (OR 1.6 [95% CI 1.3-1.9]). Lateral femorotibial compartment cartilage thickness loss, in contrast, was not significantly associated with case status. A reduction in central medial femorotibial compartment cartilage thickness was strongly associated with radiographic progression (OR 4.0 [95% CI 2.9-5.3]; P < 0.0001) and only weakly associated with pain progression (OR 1.3 [95% CI 1.1-1.6]; P < 0.01). Our findings indicate that loss of medial femorotibial cartilage thickness over 24 months is associated with the combination of radiographic and pain progression in the knee, with a stronger association for radiographic progression.

Parametric study of reverse electrodialysis using ammonium bicarbonate solution for low-grade waste heat recovery

Waste heat recovery has attracted a significant attention because of the world growth in energy demand. In this paper, we report the study on an energy recovery system utilizing low-grade waste heat below 100°C. This system called a thermal-driven electrochemical generator is composed of reverse electrodialysis (RED) power generation and thermal separation using waste heat. We especially focus on the experimental characterization of the RED process with ammonium bicarbonate (NH4HCO3) solution, which is known to be easily decomposed at the temperature around 60°C. We characterized this NH4HCO3-RED system with various parameters including the concentration difference, the membrane type, the inlet flow rate, and the compartment thickness. We found the best power density at the concentrated solution of 1.5molL−1 and the diluted solution of 0.01molL−1. The maximum power density increases as the inlet flow rate increases or the compartment thickness decreases owing to the decrease in the internal resistance. We obtained the excellent power density of 0.77Wm−2, compared with the previous studies.

Brine recovery using reverse electrodialysis in membrane-based desalination processes

Power enhancement is a key issue in the commercialization of RED. In this paper, we report a method to improve the power generation using brines discharged from two different membrane-based desalination processes. We modified a RED model proposed by Veerman and co-workers, and this modified model was in agreement with experimental results. We considered river water and seawater as the diluted solutions for RED. The power density with RO (1.48W/m2) and FO (1.86W/m2) increased 1.5-fold and 2-fold, respectively, compared with that using seawater. When seawater was used as the diluted solution, the RED power decreased considerably. We characterized the RED performance using the intermembrane distance and the inlet flow rate. The power generated monotonously increased with decreasing compartment thickness and increasing flow rate. The net power had a specific optimal value because of a drastic growth in the pumping power. In our system, the optimal intermembrane distance was 0.1mm (RO brine) and 0.3mm (FO brine). We also computed the energy cost owing to RED. The results showed that the energy consumption could be lowered by ~7.8% from the typical value for RO. We found a drastic decrease for FO with the energy consumption lowered by ~13.5%.

Histopathological changes by the use of soft reline materials: a rat model study.

AimTo assess the histopathological changes of rat palatal mucosa exposed to soft reline materials.MethodsForty-five adult female Wistar rats with controlled living conditions and fed ad libitum were employed. Palatal appliances of heat-polymerized acrylic resin Lucitone 550 were manufactured and worn by forty animals during 14 days. Five animals did not use the appliances (G1) and were used to control the appliance influence. One experimental group (n = 10) used the appliances without any relining material (G2) to control the material effect. Three experimental groups (n = 10) received the following soft reline materials below appliances: Dentusoft (G3), Dentuflex (G4), and Trusoft (G5). Appliances from half of each experimental group(n = 5) was immersed in water bath at 55°C for 10 min before use. Animals were slaughtered and the palates were fixed in 10% buffered formalin. Hematoxylin and eosin stained sections of 5 µm were analyzed by computerized planimetry. Cellular compartment, keratin and total epithelial thickness, and basement membrane length were measured to histopathological description.Analysis of variance and Tukey post-hoc test were used to data examination(α = 0.05).ResultsFor heat-treatment groups, G4 showed less elongated ridges at the basal layer interface (p = 0.037) than G2. When comparing the conditions with and without heat-treatment, only G2 showed a significant decrease in the cellular compartment, keratin layer and total epithelium thickness (p<0.05).ConclusionThe post-polymerization for Lucitone 550 was an effective method to reduce the changes in the rat palatal mucosa. The soft reline materials tested did not cause significant histopathological changes in the rat palatal mucosa.

The thickness of the anterior compartment does not indicate compartment syndrome in acutely traumatised legs?

BackgroundThe study was conducted to achieve early detection of increased compartment pressure by comparing the changes between the thickness and pressure within the musculofascial compartments after lower leg injury. MethodsWe included cases of a lower-leg fracture between January and December 2007. Bilateral lower leg compartment pressure and thickness were measured before the surgery and post-anaesthesia, and the surgery was performed within 12h after the initial trauma. The intracompartment pressure (ICP) was measured with a Wick catheter pressure monitor. The thickness (width) of the anterior compartment of lower leg was measured using ultrasound. ResultsAll data were measured within 4–6h of the injury. The average thickness in injured legs versus uninjured was 30mm (15–46mm) versus 20.4mm (13–30mm), P<0.001. The average intracompartment pressure (ICP) in injured leg versus uninjured was 45.3mmHg (26–80mmHg) versus 17.5mmHg (15–20mmHg), P<0.001. The thickness and ICP were significantly increased for injured lower legs compared to the uninjured legs, but the increase in ICP did not show a significant relationship with the change in thickness of the injured lower leg. ConclusionIn this study, the results of ICP and thickness changes of injury lower leg compared with uninjured leg revealed no statistically significant correlation. Some injuries showed a high ICP with only mild changes in thickness, while some showed a high ICP with significant changes. Although ultrasound has many advantages for the evaluation of soft tissue changes after trauma, this study revealed that thickness changes are not a predicable parameter for determining pressure on the acute fracture of lower leg.

Discretization for a spray deposition model: Criteria for temporal and spatial differencing

A spray deposition model was developed to simulate spray dispersion in open space and deposition within a citrus tree canopy. It was validated by field tests reported in earlier publications. The model is based on a compartment modeling approach where the spray cloud is spatially partitioned into several compartments, with equal thickness but increasing cross section in the direction of application. The stability of the simulation curves depends concurrently on the compartment thickness (Δx) and time step (Δt) used. Simultaneously, the needed computer memory and computational time greatly depend on Δt. In this application note, the influence of these two parameters on simulated airborne spray mass has been explored and a criterion for selecting a pair of them to optimize simulation output has been established. The criterion, Δt=Δx/ua, establishes a strong relationship of these two parameters with sprayer air velocity, ua, stressing the importance of ua in the model. The results provided critical understanding about the sensitivity of the model to the studied parameters and tend to be crucial for successful implementation of the model.

The Utility of Ultrasound in Detecting Anterior Compartment Thickness Changes in Chronic Exertional Compartment Syndrome

To test the hypothesis that patients with chronic exertional compartment syndrome (CECS) of the anterior leg compartment have an increased anterior compartment thickness (ACT) compared with control subjects after exertion using ultrasound. Prospective comparison study. Diagnostic imaging department of a tertiary care hospital. Four patients with CECS and 9 control subjects. Patients with CECS and control subjects ran on a treadmill for up to 10 minutes. Anterior compartment thickness (both groups) and anterior compartment pressure (CECS patients) were measured before exertion and at scheduled intervals after exertion. Anterior compartment thickness, percentage change in ACT from rest, and compartment pressure. Anterior compartment pressures were diagnostic of CECS using the modified Pedowitz criteria in patients with CECS. Mean percentage change in ACT from rest in patients with CECS versus control subjects at 0.5 minutes was 21.3% versus 6.32% [95% confidence interval (CI), 6.92-35.6 and 0.094-12.5, respectively; P = 0.011]; at 2.5 minutes, it was 24.6% versus 4.22% (95% CI, 10.7-38.5 and -1.85-10.3, respectively; P = 0.003); and at 4.5 minutes, it was 24.9% versus 5.08% (95% CI, 14.3-35.5 and -0.813-11.0, respectively; P = 0.003). Mean ACT in patients with CECS versus control subjects significantly increased after exertion (P = 0.003) at 0.5 minutes, 2.5 minutes, and 4.5 minutes. Ultrasonography reveals a significant increase in ACT in patients with CECS of the anterior leg compartment. Further studies are warranted to validate these findings with the goal of developing anterior leg compartment CECS ultrasound diagnostic criteria and exploring the role of using ultrasound to diagnose CECS in other compartments.

Simulation of enhanced power generation by reverse electrodialysis stack module in serial configuration

By extending the theoretical model previously formulated for the single unit problem, we fully analyze the performance of the reverse electrodialysis stack module aiming for electric power generation. In our prototype, each single unit is assembled in serial, where the mixing is allowed in connecting channels to exclude the ionic polarization. The numerical algorithm accompanying the orthogonal collocation on finite element method is applied with Legendre polynomial and Gaussian quadrature integrations to predict the ion concentration profile in each compartment, power, energy, and corresponding current densities. As the number of units increases from 1 to 8, the maximum power and the maximum current densities decrease from 9 to 1mW/m2 and from 3.6 to 1.3A/m2, respectively, but the maximum energy density increases from 1.5 to 4mWh/m3. Pursuing the justification of the validity of our RED stack module, we determine the unique compartment thickness that makes each density maximum for the specified number of units. Power and current densities increase with increasing characteristic fluid velocity, while the energy density maintains constant (ca. 0.36mWh/m3) prior to monotonic decreasing at Pe>70.

Bone mechanotransduction via T-type voltage sensitive calcium channel plays a key role in induction of the osteoarthritic phenotype

The scoring method showed excellent discrimination between disease stages: the pattern-based score was significantly different between all knee groups and the correlation across groups indicated a strong monotonic score increase with worsening of disease severity (Fig.2). In contrast, medial compartment thickness did not show significant differences until an advanced disease state. Conclusions: This study identified a characteristic progression in thickness map with increasing medial knee OA and the scoring method allowed for excellent differentiation between disease severities. The fact that thickness patterns can be statistically associated with increased OA severity is not trivial as thickness is known to vary among asymptomatic individuals and response to OA is partially subjectspecific. In fact the novel method introduced in this study might constitute a shift in the analysis of cartilage thickness. While a discrete reference (KLG) was used to assess the pattern-based score, the method provides continuous scoring and thus has the potential to detect more subtle differences. Clearly the method will need to be tested with larger cohorts and other OA conditions. However, the robust statistical findings here are very promising given the limited size of the training datasets used for this study.

Bipolar membrane electrodialysis for the alkalinization of ethanolamine salts

Bipolar membrane electrodialysis for the production of organic bases, in contrast to organic acids, has received little attention in the scientific literature. In the present work we have investigated and compared different membrane configurations for the alkalinization of monoethanolamine salts into the organic base monoethanolamine. A current utilization of only 36% has been obtained for a two compartment configuration with bipolar and anion-exchange membranes. Proton tunneling through the anion-exchange membrane has been identified as the main reason for this relatively low current utilization. Minimizing proton tunneling by employing proton blocking anion-exchange membranes and using a three compartment configuration, the current utilization could be increased to 80%. This bipolar membrane configuration acts as a concentration step as well. A MEA concentration of 32 wt% in the base compartment could be achieved. A disadvantage of the three compartment configuration is the relatively high unit cell potential drop of 3.1 V at a current density of 1000 A m−2 using a compartment thickness of 0.75 mm.

Capacity reduction and fire load factors for LRFD of steel columns exposed to fire

Capacity reduction and fire load factors corresponding to the load and resistance factor design (LRFD) format are developed for steel columns exposed to fire. A sample deterministic framework to determine fire and steel temperatures and the capacity of steel columns is adopted for this analysis to structure the methodology. A specific number of parameters that affect the structural response, including the fire load, ratio of floor area to the total area of the fire compartment, opening factor, thermal absorptivity of compartment boundaries, thickness, density and thermal conductivity of insulation, dead load, and live load are taken as random variables. Mechanical and sectional properties of steel (e.g., yield strength, cross-sectional area, etc.), are also considered to be random variables. The effect of active fire protection systems (e.g., sprinklers, smoke and heat detectors, fire brigade, etc.), in reducing the probability of occurrence of a severe fire is included. Given the choice of framework and based on detailed reliability analyses, it is shown that the capacity reduction and fire load factors should vary depending on the presence of active fire protection systems in a building.