Measurement Of Pressure Changes Research Articles

SPARC: Current Steering To Selectively Recruit Nerves Of The Lower Urinary Tract

Lack of bladder control has a substantial impact on quality of life, with consequences ranging from sleep deprivation and embarrassment to bladder and kidney infection. Current methods to address lower urinary tract (LUT) dysfunction, including pharmacological interventions and catheterization, are insufficient to restore bladder control and may lead to rehospitalization, especially after spinal cord injury. Previously, we have used epidural spinal cord stimulation (SCS) to selectively recruit nerves innervating the LUT, a promising result that suggests this method of stimulation could be used to address LUT dysfunction. Epidural SCS has been in use clinically for pain relief for over 50 years, and is a minimally‐invasive way to access these neural pathways. However, current clinical leads have large electrodes that make it difficult to spatially limit the region targeted by SCS. Here, we use a high‐density epidural spinal cord electrode and multipolar stimulation patterns to reduce off‐target neural recruitment and refine the selective activation of LUT nerves.We placed a high‐density epidural spinal cord electrode (MicroLeads Inc) at three locations of the sacral spinal cord and cauda equina in cats under isoflurane anesthesia. To record antidromic compound action potentials evoked by SCS, we recorded from nerve cuffs (MicroLeads Inc) on the sciatic nerve, pelvic nerve, as well as the pudendal nerve and its branches. To measure muscle recruitment during stimulation, we recorded electromyogram (EMG) activity from the external urethral sphincter, external anal sphincter, pelvic floor and gluteus. Using catheters in the bladder and urethra, we measured pressure changes during stimulation. We stimulated on all electrodes of the spinal cord arrays individually, as well as in bipolar and tripolar sets of electrodes to determine the effect of current steering on LUT nerve recruitment.We were able to recruit LUT nerves with all configurations of stimulation electrodes. However, monopolar stimulation resulted in substantial selective recruitment of the off‐target sciatic nerve, representing 59% of selective responses at the most rostral sacral location, 72% at the more caudal sacral location, and 27% at the cauda equina. By using bipolar and tripolar stimulation across the same electrodes, we were able to steer current so that electrodes selective for the sciatic nerve with monopolar stimulation were selective for LUT responses. Additionally, recruitment thresholds of monopolar stimulation were typically lower, between 50–1000 μA, than those of multipolar stimulation, which ranged from 100–2800 μA. We were also able to change the EMG recruitment with changes in electrode configurations, allowing targeting of functionally‐relevant muscles.We were able to map the recruitment of LUT nerves and muscles across several levels of the spinal cord using both monopolar and multipolar stimulation. By using these stimuli to access LUT nerves and muscles, we hope to systematically modify function in the LUT, providing a potential route to treat LUT dysfunction.Support or Funding InformationNIH SPARC award 1OT2OD024908 and Craig H. Neilsen Foundation, award 476681

Aquifer Imaging with Oscillatory Hydraulic Tomography: Application at the Field Scale.

Modeling and laboratory experiments have demonstrated the ability of oscillatory hydraulic tomography (OHT) to characterize heterogeneity in aquifer hydraulic properties. In OHT, a location is stressed via periodic pumping/injection at a set frequency, and the resulting head signal is measured at a number of monitoring locations. The source of oscillations is repeatedly moved, allowing tomographic imaging of aquifer properties. Changing the period of oscillation also results in observations with additional information. In theory, OHT is comparable to other hydraulic tomography methods in that distributed pressure change measurements provide characterization information. In practice, OHT has several benefits including: (1) little to no water injected into or extracted from the aquifer; and (2) an observational signal at a set period that can be easily extracted in the presence of noise. We report the first field application of OHT, carried out at the Boise Hydrogeophysical Research Site (BHRS) using an oscillating signal generator with a very small cycling volume of <2 L, and a period range of 5 to 70 s. For these tests, signals were detected at distances of over 15 m. After processing to extract periodic signal properties, we perform tomography using a frequency-domain numerical model for groundwater flow. In comparing results against prior characterization results from the BHRS, we find moderate to strong positive correlations between K profiles estimated via different methods at multiple wells, with moderate overall correlation between estimated three-dimensional (3D) K volumes.

A New Principle for Measuring the Average Relative Humidity in Large Volumes of Non-Homogenous Gas.

Due to the current extent of arid regions, the pressure on available water resources is increasing. A suitable measure for water availability and dynamics in dry soil is the relative humidity of the soil air. Due to the heterogeneity of soil, water inputs, and root water uptake, the humidity of soil air will vary in space. Therefore, area-representative measurement methods are needed to find a representative measure of the soil water status. Existing sensors for the direct determination of relative humidity only represent a single location with a spatial extent of up to several cm. We introduce a new measuring principle that averages over a spatially heterogeneously distributed relative humidity. It is based on the selective diffusion of water vapor pressure through a tubular semipermeable membrane to/from a closed measurement chamber. A measured pressure change is sensitive to the water vapor pressure and enables, without any external calibration, to estimate an average of the relative humidity. The comparison of our first laboratory prototype of the new sensor with calibrated reference sensors for relative humidity in a range of approx. 4 to 100% proves the linearity of the measuring method and its high accuracy. For further optimization improved reference measurement techniques are necessary. A potential application is the improvement of water use efficiency in irrigated agriculture.

Design and testing of microbubble-based MRI contrast agents for gastric pressure measurement.

PurposeThis work demonstrates specifically tailored microbubble‐based preparations and their suitability as MRI contrast agents for ingestion and measuring temporal and spatial pressure variation in the human stomach.MethodsEnhanced alginate spheres were prepared by incorporating gas‐filled microbubbles into sodium alginate solution followed by the polymerization of the mixture in an aqueous calcium lactate solution. The microbubbles were prepared with a phospholipid shell and perfluorocarbon gas filling, using a mechanical cavitational agitation regime. The NMR signal changes to externally applied pressure and coming from the enhanced alginate spheres were acquired and compared with that of alginate spheres without microbubbles. In vivo investigations were also carried out on healthy volunteers to measure the pressure variation in the stomach.ResultsThe MR signal changes in the contrast agent exhibits a linear sensitivity of approximately 40% per bar, as opposed to no measurable signal change seen in the control gas‐free spheres. This novel contrast agent also demonstrates an excellent stability in simulated gastric conditions, including at body temperature. In vivo studies showed that the signal change exhibited in the meal within the antrum region is between 5% and 10%, but appears to come from both pressure changes and partial volume artifacts.ConclusionThis study demonstrates that alginate spheres with microbubbles can be used as an MRI contrast agent to measure pressure changes. The peristaltic movement within the stomach is seen to substantially alter the overall signal intensity of the contrast agent meal. Future work must focus on improving the contrast agent's sensitivity to pressure changes.

The Impact of a Place for the Measurement of Cylinder Pressure of Marine Piston Engine on the Indicator Diagrams and Indicator Parameters

Abstract The article discusses one of the most popular methods of diagnosing selected damages of marine piston engines, which is the indication or measurement of pressure changes in the engine’s combustion chamber. Improving the quality of indicator diagrams may contribute to the increase in the efficiency of using the parameters indicated in the diagnostics of marine piston engines. Measurement errors during engine indication are primarily caused by measuring channels that connect the combustion chamber to the pressure sensor. One way to avoid these errors is to install the pressure sensor directly in the combustion chamber. It seems that it is possible to eliminate these errors. However, there is a risk that the pressure sensor will be damaged by the effect of high temperature on it during combustion of the fuel-air mixture in the engine’s combustion chamber. The article presents the results of tests that indicate that the measured temperatures in the place where the sensor was installed (in the combustion chamber) did not exceed the critical value specified by the pressure sensor manufacturer. The article also presents the results of cylinder pressure measurement not only in the combustion chamber but also in two other points - on the thread of the indicator cock and in the measuring channel between the indicator cock and the cylinder head. The tests were carried out in a wide range of engine load technically efficient and with simulated damage in the fuel injection system. The article presents a comparative analysis of the parameters read out of the indicator diagram for the three above-mentioned pressure measurement locations. It was shown that the pressure measurements carried out directly in the combustion chamber are free from errors resulting from the influence of measuring channels and indicator cock.

Integration of wellbore pressure measurement and groundwater quality monitoring to enhance detectability of brine and CO2 leakage

Leakage detectability is a key consideration in evaluating the effectiveness of a measurement, monitoring and verification (MMV) plan for a geologic carbon storage (GCS) project. While studies have shown that surface-based, geophysical monitoring methods may be sensitive enough to detect CO2 leakage, these methods are an indirect indicator of leakage. A drawback to relying on direct geochemical monitoring is that by the time a significant leak is confirmed, it may be too late to mitigate or remediate the environmental impacts. In this study, we combine information from geophysical and geochemical monitoring methods to provide an integrated diagnosis of leakage events. The detectability for various monitoring parameters (pH, TDS, alkalinity, Ca, Cl, Na, and pressure) collected from monitoring wells are evaluated by leakage detection probability, using simulated wellbore-leakage/plume-migration events and monitoring scenarios for a hypothetical GCS operation at the Kimberlina site in California, USA. The NUFT code is used to model these events, by coupling wellbore-leakage simulations to 3-dimensional reactive, multi-phase, flow and transport simulations of brine and CO2 leakage-plume migration in aquifers overlying the GCS reservoir. Wellbore leakage in legacy wells located 1.4, 3.4 and 6.8 km from the CO2 injector is evaluated for a range of (1) wellbore bottom-hole pressure and CO2 saturation determined by GCS simulations, (2) regional groundwater gradient in the aquifers, and (3) wellbore permeability. Simulated leakage-induced changes in seven monitoring parameters at different depths are used to calculate the corresponding detection probabilities, based on the background distribution data and selected monitoring-technology detection thresholds. The responses for these monitoring parameters are tested and combined to enhance the overall detectability. The results indicate the leakage signals are more easily detected at shallower depths where buoyant CO2 has migrated and flashed from supercritical to gas phase, causing a large increase in CO2 volume. While the results suggest pH monitoring is more responsive to the simulated leakage events than TDS monitoring at shallower depths, TDS changes may be more readily observed at greater depths. The addition of carbonate alkalinity can confirm CO2 leakage detection and help distinguish CO2 leakage from other contamination sources. Direct pressure change measurements are very sensitive to leakage, but the rapid and broad propagation of the pressure response hinders using such measurements to easily locate the origin of leakage. Combining measurements could greatly improve the confidence of leakage diagnosis. High bottom-hole CO2 saturation, such as that for a leaky well close to the injector (˜1.4 km), high regional groundwater gradient, and high wellbore permeabilities all increase the leakage plume size, and thus the leakage detectability. Our analysis suggests pressure monitoring is a valuable indicator of leakage events at early stages, while pH, TDS and carbonate alkalinity monitoring can directly diagnose leakage impacts by providing more detailed information in the groundwater receptor. Finally, an example Bayesian belief network model is presented for evaluating the effect of risk reduction options in terms of joint monitoring detection probability using the associated simulation scenarios. This framework is demonstrated to inform how pressure and groundwater quality information can be integrated into site MMV and risk management plans.

Investigation of Drag Reduction Technologies for Light-Duty Vehicles Using Surface, Wake and Underbody Pressure Measurements to Complement Aerodynamic Drag Measurements.

Amulti-year, multi-vehicle study was conducted to quantify the aerodynamic drag changes associated with drag reduction technologies for light-duty vehicles. Various technologies were evaluated through fullscale testing in a large low-blockage closed-circuit wind tunnel equipped with a rolling road, wheel rollers, boundary-layer suction and a system to generate road-representative turbulent winds. The technologies investigated include active grille shutters, production and custom underbody treatments, air dams, wheel curtains, ride height control, side mirror removal and combinations of these.This paper focuses on mean surface-, wake-, and underbody-pressure measurements and their relation to aerodynamic drag. Surface pressures were measured at strategic locations on four sedans and two crossover SUVs. Wake total pressures were mapped using a rake of Pitot probes in two cross-flow planes at up to 0.4 vehicle lengths downstream of the same six vehicles in addition to a minivan and a pick-up truck. A smaller rake was used to map underbody total pressures in one cross-flow plane downstream of the rear axle for three of these vehicles.The results link drag reduction due to various technologies with specific changes in vehicle surface, rear underbody and wake pressures, and provide a database for numerical studies. In particular, the results suggest that existing or idealized prototype technologies such as active grille shutters, sealing the external grille and ride height control reduce drag by redirecting incoming flow from the engine bay or underbody region to smoother surfaces above and around the vehicle. This mechanism can enhance the reduction in wheel drag due to reduced wheel exposure at lowered ride height. Sealing the external grille was found to redirect the flow more efficiently than closing the grille shutters, and resulted in greater drag reduction. Underbody treatments were also found in some cases to redistribute the flow around the vehicle to reduce pressure drag in addition to underbody friction drag. The magnitude and spatial extent of the measured pressure changes due to the various technologies were often consistent with the amount of drag reduction.

Integration of Wellbore Pressure Measurement and Groundwater Quality Monitoring to Enhance Detectability of Brine and CO2 Leakage

Abstract Leakage detectability is a key consideration in evaluating the effectiveness of a measurement, monitoring and verification (MMV) plan for a geologic carbon storage (GCS) project. While studies have shown that surface-based, geophysical monitoring methods may be sensitive enough to detect CO2 leakage, these methods are an indirect indicator of leakage. A drawback to relying on direct geochemical monitoring is that by the time a significant leak is confirmed, it may be too late to mitigate or remediate the environmental impacts. In this study, we combine information from geophysical and geochemical monitoring methods to provide an integrated diagnosis of leakage events. The detectability for various monitoring parameters (pH, TDS, alkalinity, Ca, Cl, Na, and pressure) collected from monitoring wells are evaluated by leakage detection probability, using simulated wellbore-leakage/plume-migration events and monitoring scenarios for a hypothetical GCS operation at the Kimberlina site in California, USA. The NUFT code is used to model these events, by coupling wellbore-leakage simulations to 3-dimensional reactive, multi-phase, flow and transport simulations of brine and CO2 leakage-plume migration in aquifers overlying the GCS reservoir. Wellbore leakage in legacy wells located 1.4, 3.4 and 6.8 km from the CO2 injector is evaluated for a range of (1) wellbore bottom-hole pressure and CO2 saturation determined by GCS simulations, (2) regional groundwater gradient in the aquifers, and (3) wellbore permeability. Simulated leakage-induced changes in seven monitoring parameters at different depths are used to calculate the corresponding detection probabilities, based on the background distribution data and selected monitoring-technology detection thresholds. The responses for these monitoring parameters are tested and combined to enhance the overall detectability. The results indicate the leakage signals are more easily detected at shallower depths where buoyant CO2 has migrated and flashed from supercritical to gas phase, causing a large increase in CO2 volume. While the results suggest pH monitoring is more responsive to the simulated leakage events than TDS monitoring at shallower depths, TDS changes may be more readily observed at greater depths. The addition of carbonate alkalinity can confirm CO2 leakage detection and help distinguish CO2 leakage from other contamination sources. Direct pressure change measurements are very sensitive to leakage, but the rapid and broad propagation of the pressure response hinders using such measurements to easily locate the origin of leakage. Combining measurements could greatly improve the confidence of leakage diagnosis. High bottom-hole CO2 saturation, such as that for a leaky well close to the injector (˜1.4 km), high regional groundwater gradient, and high wellbore permeabilities all increase the leakage plume size, and thus the leakage detectability. Our analysis suggests pressure monitoring is a valuable indicator of leakage events at early stages, while pH, TDS and carbonate alkalinity monitoring can directly diagnose leakage impacts by providing more detailed information in the groundwater receptor. Finally, an example Bayesian belief network model is presented for evaluating the effect of risk reduction options in terms of joint monitoring detection probability using the associated simulation scenarios. This framework is demonstrated to inform how pressure and groundwater quality information can be integrated into site MMV and risk management plans.

Novel Mapping Method for the Intraoperative Neurophysiologic Monitoring of Sexual Function During Prostate Surgery

The occurrence of urinary incontinence and erectile dysfunction after surgical treatment for prostate cancer is a significant and lingering problem. The aim of this study is to revise and improve older techniques of intraoperative cavernous nerve mapping already in use to improve accuracy and reliability. We prospectively studied this technique in 12 patients suffering from prostate cancer. Inhalation or intravenous anesthetic regimen was used with nondepolarizing muscle relaxants. Stimulation protocol was 30 Hz, 0.2 ms, 10 to 20 mA intensity and a maximum duration of 30 seconds. Recording was performed with a system for measuring pressure changes using a stainless steel needle electrode inside the cavernous bodies. Stimulation was systematically performed at three distinct moments during the surgery at various points. An increase or decrease in pressure of 4 cm of H20 in the cavernous bodies was considered a positive result and negative response when no changes occurred after 30 seconds of continuous stimulation. Of patients, 91.6% had positive responses to initial stimulation. The anesthetic regimen did not appear to significantly influence the responses in our series. In light of the results of this study, the stimulation of the cavernous nerves may be a viable technique in the right context, which includes good patient selection (young patients with a localized tumor and with preserved potency). The major limitation is that mapping techniques are useful to localize functional nerves, but not to monitor function in a continuous manner.

Potential of Renewable Energy Biogas from Plant (Hyacinth)

&lt;p class="Abstract"&gt;Energy is one of the basic human needs, both in the form of electricity and energy in the form of heat / gas. The increase in Indonesia's population has increased by 1.3% every year, this is comparable to the increase in energy needs. Current conditions illustrate that the fulfillment of energy needs is sourced more from fossil materials that cannot be renewed, therefore a solution is needed to overcome these problems by finding and finding potential alternative energy sources that can meet human needs. One of the energy that can be utilized is biogas. Biogas is a process of fermentation of organic matter that produces methane gas. Organic materials available in nature are abundant, one of which is organic matter derived from water hyacinth. For this reason, a research study is needed by identifying the potential of biogas energy from water hyacinth. This research is an experimental research, the data collection technique is done by quantitative methods. The tools needed are a manometer, thermometer and biogas reactor. This research was conducted by measuring the temperature and pressure produced by biogas made from organic water hyacinth. The results obtained showed that the biogas produced from water hyacinth produced a gas odor that was relatively not too stinging and the gas formation process was faster. Gas pressure measurements are carried out using a monometer by calculating the difference in the height of water pressure in the U pipe. Measurements of pressure changes are carried out for 20 days by conditioning external factors such as temperature and humidity. The study was conducted to examine the effect of adding water hyacinth to biogas organic matter. The results obtained that t count&amp;gt; t table is the value of t arithmetic (8.183)&amp;gt; t table (2.093) and the significance level of 0.000 &amp;lt;0.05. This means that there are differences in biogas production between before adding water hyacinth and after adding water hyacinth.&lt;/p&gt;

Isochoric vitrification: An experimental study to establish proof of concept

Ice-free vitreous cryopreservation (vitrification) is regarded as the principal method for avoiding ice crystallization damage in cryopreserved tissues and organs. We previously established the fundamental thermodynamics of isochoric (constant volume) systems for cryopreservation, and now extend this novel approach to vitrification in an isochoric system. This was achieved by measuring pressure changes in a 2 ml isochoric chamber containing a variety of aqueous solutions of the ubiquitous cryoprotective additives (CPA), dimethyl sulfoxide (Me2SO) and Propane-diol. The CPAs, ranging in concentrations from 0 to 49%(w/v), were prepared in a proprietary preservation solution (Unisol®) in anticipation of future applications to tissue and organ banking. Pressures developed in the system were monitored as a function of CPA concentration and cooling rate when the isochoric chamber was cooled to cryogenic temperature (−160 °C). This study corroborated our previous findings that pressure increases in accordance with the thermodynamics of partially frozen systems of low concentrations of CPAs. A key finding of this study was that in an isochoric system of higher concentrations of CPA, which vitrifies, there is no increase in pressure. In fact, an increase in pressure is a measure of failure to vitrify and a measure of devitrification. Comparison with results from the literature show that the concentration of CPAs needed for vitrification in an isochoric chamber is substantially lower than that needed for vitrification in isobaric systems at 1 atm and hyperbaric systems at 1000 atm. In addition, isochoric chambers are much more effective in promoting vitrification than hyperbaric pressure chambers, and are less expensive, easier to design, and implement.

The Effect of Sulfur Concentration in the Metal on the Mass Transfer of Phosphorus in Bloated Metal Droplets

In Basic Oxygen Steelmaking, metal droplets created by the impact of the oxygen jet will swell due to internal decarburization when they react with oxidizing slag in the emulsion zone. In this study, the dephosphorization behavior of bloated metal droplets containing different sulfur concentrations is investigated in the temperature range from 1813 to 1913 K using X‐ray fluoroscopy coupled with constant volume pressure change measurements and chemical analysis of quenched samples. The results show that higher sulfur droplets (&gt;0.017 wt%) have a much longer incubation period for swelling than those with lower sulfur (&lt;0.017 wt%). Due to this different swelling behavior, the dephosphorization rate for high sulfur droplets is found to be not heavily affected by the experimental temperature compared to the case of lower sulfur droplets. Employing a mixed control model including mass transfer and chemical reaction, the effect of temperature on dephosphorization kinetics is further discussed. The mass transfer coefficient in the metal, km, is found to increase slightly with increasing temperature for droplets with 0.021 wt% sulfur. It is also found that lower rates of CO formation result in less stirring in the droplet and lower mass transfer rates of phosphorus for high sulfur droplets.

Facile Fabrication of a Flexible LiNbO3 Piezoelectric Sensor through Hot Pressing for Biomechanical Monitoring.

Wearable pressure sensors have attracted increasing attention for biomechanical monitoring due to their portability and flexibility. Although great advances have been made, there are no facile methods to produce sensors with good performance. Here, we present a simple method for manufacturing flexible and self-powered piezoelectric sensors based on LiNbO3 (LN) particles. The LN particles are dispersed in polypropylene (PP) doped with multiwalled carbon nanotubes (MWCNTs) by hot pressing (200 °C) to form a flexible LN/MWCNT/PP piezoelectric composite film (PCF) sensor. This cost-effective sensor has high sensitivity (8 Pa), fast response time (ca. 40 ms), and long-term stability (>3000 cycles). Measurements of pressure changes from peripheral arteries demonstrate the applicability of the LN/MWCNT/PP PCF sensor to biomechanical monitoring as well as its potential for biomechanics-related clinical diagnosis and forecasting.

High-temperature high-pressure calorimeter for studying gram-scale heterogeneous chemical reactions.

We present an instrument for measuring pressure changes and heat flows of physical and chemical processes occurring in gram-scale solid samples under high pressures of reactive gases. Operation is demonstrated at 1232 °C under 33 bars of pure hydrogen. Calorimetric heat flow is inferred using a grey-box non-linear lumped-element heat transfer model of the instrument. Using an electrical calibration heater to deliver 900 J/1 W pulses at the sample position, we demonstrate a dynamic calorimetric power resolution of 50 mW when an 80-s moving average is applied to the signal. Integration of the power signal showed that the 900 J pulse energy could be measured with an average accuracy of 6.35% or better over the temperature range 150-1100 °C. This instrument is appropriate for the study of high-temperature metal hydride materials for thermochemical energy storage.

The Influence of Sulfur on Dephosphorization Kinetics Between Bloated Metal Droplets and Slag Containing FeO

The bloating behavior of metal droplets and the dephosphorization behavior of bloated droplets at 1853 K (1580 °C) were investigated using X-ray fluoroscopy coupled with constant volume pressure change measurements and chemical analysis of quenched samples. The effect of sulfur content on dephosphorization kinetics was studied during the decarburization period. The slag foamed during the reaction forming a foamy layer over a dense layer. After a short incubation period, the droplets became bloated due to internal decarburization. The bloated droplets floated from the dense slag into the foamy slag. The behavioral changes are directly related to the effect of sulfur on the incubation time for swelling. The dephosphorization reaction was very fast; droplets with low sulfur contents experienced phosphorus reversion shortly after entering the foamy slag, while those with higher sulfur content took a longer time to swell and went through reversion before they entered the foam. The dephosphorization rate and maximum phosphorus partition were higher at lower CO evolution rates because the dynamic interfacial oxygen potential increased with the decreasing oxygen consumption rate. The rate controlling step for dephosphorization was initially a combination of mass transport in both the metal and the slag. As the iron oxide in the slag was depleted, the rate control shifted to mass transport in slag.

Intraoperative neuromonitoring of hypogastric plexus branches during surgery for rectal cancer - preliminary report.

The aim of this study was to present our preliminary experience with intraoperative neuromonitoring during rectal resection. We qualified 4 patients (2 women, 2 men; age 42 - 53 years) with rectal cancer for surgery with intraoperative neuromonitoring. In all patients, functional tests of the anorectal area were performed before surgery. Action potentials from the sphincter complex in response to nerve fiber stimulation were recorded with electrodes implanted before surgery. Moreover, we inserted a standard, 18FR Foley's urinary catheter to which a T-tube was connected to allow urine outflow and measurement of pressure changes in the bladder induced by detrusor contractions during stimulation. Setting up neuromonitoring prolonged surgery time by 30 to 40 minutes, or even by 60 to 80 minutes in the case of the first two patients. Neuromonitoring itself took additional 20 to 30 minutes during surgery. In all patients, we stimulated branches of the inferior hypogastric plexus in their anatomical position during dissection. In three patients, we evoked responses both from the bladder and the sphincter in all planes of stimulation. In one patient, there was no response from the left side of the bladder, and in the same patient, we observed symptoms of neurogenic bladder. Based on the available literature and our own experience, we state that monitoring of bladder pressure and electromyographic signals from rectal sphincters enables visualization and preservation of autonomic nervous system structures, both sympathetic and parasympathetic. Intraoperative signals seem to be correlated with clinical presentation and functional examinations after surgery. In order to objectify our results, it is necessary to perform functional examinations before and after surgery in a larger group of patients.

Monitoring of thermal stresses in pressure components using inverse heat conduction methods

PurposeThe purpose of this paper is to present a method for monitoring transient thermal stresses. This paper also presents the analysis of thermal stresses of boiler pressure element heating during the start-up in real conditions. The inverse methods are used to determine the wall temperature, whereas the commercial software ANSYS is used to determine the thermal stresses in the pressure component.Design/methodology/approachThe method is based on the solution of the inverse heat conduction problem. Thermal stresses are determined indirectly taking into account the measured temperature values at selected points on the outer wall of a pressure component. First, the transient temperature distribution in the entire pressure element is calculated, and then, thermal stresses are determined by the finite element method. Measured pressure changes are used to determine the stresses resultant from the internal pressure.FindingsThe obtained stresses and temperature in the thick-walled pipe are illustrated and compared with experimental data. Satisfactory agreement was found between computational and experimental results.Originality/valueThe method can be used in the monitoring of thermal and mechanical stresses during the boiler’s start-up and shut-down. Because the temperature distribution at each time level is determined, it can be applied as a thermal load during the structural analysis.

Comparison of compressive forces caused by various cannulated cancellous screws used in arthroscopic ankle arthrodesis

BackgroundWhen performing arthroscopic ankle arthrodesis for end-stage ankle arthritis, internal fixation is performed using bone screws after appropriate preparation.However, optimal characteristics of bone screws have not been examined in terms of pressure force. Objective comparisons of bone-screw performance may provide information on procedures for arthroscopic ankle arthrodesis. The study objectives were to determine whether it was possible to measure compressive force changes using the newly developed device and to infer all screw characteristics from measurement results when used in actual surgeries. In addition, we performed experiments on cadavers to verify whether the experimental results could be applied to the joints of living subjects.MethodsThree types of screws (S1, S2, and S3) were inserted into the unique measurement device, and the changes in pressure were measured for each 45° turn. Changes in pressure and maximum pressure force were recorded after the application of the screws. After reaching the maximum pressure in the simulated bone, further screw rotations were accompanied by a gradual pressure decrease to 0 MPa. We also measured pressure changes in a similar manner by inserting a miniature pressure sensor into the talocrural joints of cadavers.ResultsThe mean maximum pressure ± standard deviation for S1, S2, and S3 were 0.832 ± 0.164 MPa, 0.434 ± 0.116 MPa, and 0.414 ± 0.127 MPa, respectively. Pressure slopes to the maximum did not significantly differ between the screws in the simulated bone, and a subsequent pressure decrease to 0 MPa was significantly more rapid for S1 than for S2 and S3. Although pressure failure after the overtightening of screws was only observed in the simulated bone, patterns of pressure vs. rotation angle were similar in simulated and cadaveric bones. The pressure profile characteristics of three different screw types were determined.ConclusionsWe were able to measure the compressive force changes using the newly developed device when the screws were inserted. On the basis of the measurement results, we were able to infer the characteristics of all screws when used in actual surgery.

A Kalman filter to estimate altitude change during a fall.

Barometers have been incorporated into fall detectors in order to enhance the accuracy of fall detection algorithms, however they are power-hungry devices. We present an offline evaluation of a Kalman filter (KF) for estimating the pressure change during a fall that enables low-power operation of the barometer. The KF takes advantage of the fact that a semi-permeable air membrane on a waterproof fall detector enclosure causes a delay in the equilibrium between internal and external enclosure pressure, and this delay enables the barometer to be switched off until a free-fall is detected. We assessed the KF using data obtained from simulated falls and activities of daily living. The KF was able to differentiate between fall and non-fall activities, with the average measured pressure change during a fall of 8 Pa best determined using a delay in pressure equalization of 20 seconds. The KF detected a change in altitude faster than a simple moving average filter (MAF), reaching 66% of its final value before the MAF was able to initialize.

Investigation of different additives to monoethanolamine (MEA) as a solvent for CO2 capture

The influence of various additives including potassium lysinate (PL), potassium glycinate (PG), potassium carbonate (K2CO3), 2-(1-piperazinyl)-ethylamine (PZEA), trisodium phosphate (TSP) and tetraethylenepentamine (TEPA) to monoethanolamine (MEA) as solvent for carbon dioxide (CO2) was evaluated experimentally. In order to determine the absorption rate and solubility of carbon dioxide into aqueous solutions of MEA in the presence of these activators, a vapor-liquid equilibrium (VLE) apparatus was used to measure pressure changes versus time at a constant total blend concentration of 2.5 mol dm−3 (M) and CO2 partial pressures between 0 and 50 kPa at 313.15 K. In all the experiments, the molar ratio of the additive to MEA was set to 0.25, 0.66 and 1. The results indicate that the 1.25 M MEA + 1.25 M TEPA system reaches the maximum loading capacity (mole CO2/mole solution) of 1.32 and has the highest absorption rate. It can be concluded that the 1.25 M MEA + 1.25 M TEPA blend solution can be a good candidate for CO2 capture.