Original Article Hyperbaric spinal anesthesia with ropivacaine coadministered with sufentanil for cesarean delivery: a dose-response study

Abstract: Adjuvant sufentanil could achieve effective spinal anesthesia with low dose of hyperbaric ropivacaine for cesarean delivery. Two previous studies had calculated the 50% effective dose (ED50) of intrathecal ropivacaine coadministered with sufentanil for cesarean delivery. However, the 95% effective dose (ED95) of intrathecal hyperbaric ropivacaine coadministered with sufentanil for cesarean delivery remains uncertain. This study determined the ED95 of intrathecal hyperbaric ropivacaine coadministered with sufentanil for cesarean delivery. 80 ASA physical status I or II parturients undergoing elective cesarean delivery were enrolled in this prospective, randomized, double-blind investigation. A combined spinal and epidural anesthesia was performed at the L3-L4 interspace. Patients received a dose of spinal ropivacaine coadministered with sufentanil 5 μg diluted to 3.0 ml with normal saline and 0.5 ml of 10% dextrose: 7.5 mg (n = 20), 9.0 mg (n = 20), 10.5 mg (n = 20), or 12 mg (n = 20). An effective dose was defined as a dose that provided bilateral sensory block to T7 within 10 min after intrathecal drug administration and required no epidural top-up for surgery to be completed. The ED50 and ED95 values for successful anesthesia were determined using a logistic regression model. The ED50 (95% confidence interval [CI]) for successful anesthesia was 8.4 (4.0-9.8) mg and the ED95 (95% CI) was 11.4 (9.7-13.9) mg. The results show that the ED95 of intrathecal hyperbaric ropivacaine coadministered with sufentanil 5 μg for cesarean delivery was 11.4 mg. The addition of sufentanil could significantly reduce the dosage of ropivacaine

A Comparative Study of Systolic and Diastolic Mechanical Synchrony in Canine, Primate, and Healthy and Failing Human Hearts.

Aim: Mechanical dyssynchrony (MD) is associated with heart failure (HF) and may be prognostically important in cardiac resynchronization therapy (CRT). Yet, little is known about its patterns in healthy or diseased hearts. We here investigate and compare systolic and diastolic MD in both right (RV) and left ventricles (LV) of canine, primate and healthy and failing human hearts. Methods and Results: RV and LV mechanical function were examined by pulse-wave Doppler in 15 beagle dogs, 59 rhesus monkeys, 100 healthy human subjects and 39 heart failure (HF) patients. This measured RV and LV pre-ejection periods (RVPEP and LVPEP) and diastolic opening times (Q-TVE and Q-MVE). The occurrence of right (RVMDs) and left ventricular systolic mechanical delay (LVMDs) was assessed by comparing RVPEP and LVPEP values. That of right (RVMDd) and left ventricular diastolic mechanical delay (LVMDd) was assessed from the corresponding diastolic opening times (Q-TVE and Q-MVE). These situations were quantified by values of interventricular systolic (IVMDs) and diastolic mechanical delays (IVMDd), represented as positive if the relevant RV mechanical events preceded those in the LV. Healthy hearts in all species examined showed greater LV than RV delay times and therefore positive IVMDs and IVMDd. In contrast a greater proportion of the HF patients showed both markedly increased IVMDs and negative IVMDd, with diastolic mechanical asynchrony negatively correlated with LVEF. Conclusion: The present IVMDs and IVMDd findings have potential clinical implications particularly for personalized setting of parameter values in CRT in individual patients to achieve effective treatment of HF

LSTM Network-Assisted Binocular Visual-Inertial Person Localization Method under a Moving Base

In order to accurately locate personnel in underground spaces, positioning equipment is required to be mounted on wearable equipment. But the wearable inertial personnel positioning equipment moves with personnel and the phenomenon of measurement reference wobble (referred to as moving base) is bound to occur, which leads to inertial measurement errors and makes the positioning accuracy degraded. A neural network-assisted binocular visual-inertial personnel positioning method is proposed to address this problem. Using visual-inertial Simultaneous Localization and Mapping to generate ground truth information (including position, velocity, acceleration data, and gyroscope data), a trained neural network is used to regress 6-dimensional inertial measurement data from the IMU data fragment under the moving base, and a position loss function is constructed based on the regressed inertial data to reduce the inertial measurement error. Finally, using vision as the observation quantity, the point feature and inertial measurement data are tightly coupled to optimize the mechanism to improve the personnel positioning accuracy. Through the actual scene experiment, it is verified that the proposed method can improve the positioning accuracy of personnel. The positioning error of the proposed algorithm is 0.50%D, and it is reduced by 92.20% under the moving base

Effect of Loading Rate and Confining Pressure on Strength and Energy Characteristics of Mudstone under Pre-Cracking Damage

In order to explore the deformation and failure law of deep surrounding rock roadway disturbed by strong dynamic pressure, the triaxial mechanical properties of mudstone samples under pre-cracking damage conditions were tested to study the deformation and failure characteristics and energy evolution mechanism in the damage process, under different loading rates and confining pressures. In the mechanical experiment, the specimen is pre-cracked to simulate the damage and failure of surrounding rock during roadway excavation, and the damage degree model of rock specimen is established. The results show that the loading rate and confining pressure have significant effects on the peak strength and energy characteristics of mudstone at the average damage degree of 0.12, and the peak strength increases with the increase in confining pressure and loading rate. Under the same confining pressure, the energy increases first, and then decreases with the increase in loading rate, and the loading rate at the turning point is called the critical loading rate. Under the same confining pressure, the closed stress of mudstone gradually increases with the increase in loading rate, and the closed stress and loading rate show a good linear relationship. Through the fitting relationship, it is found that the fitting correlation coefficient between the closed stress of mudstone and the loading rate is as high as 0.99. The elastic strain energy ratio presents a composite function of exponential function with natural constant e, which is a nonlinear process

Effect of Loading Rate and Confining Pressure on Strength and Energy Characteristics of Mudstone under Pre-Cracking Damage

In order to explore the deformation and failure law of deep surrounding rock roadway disturbed by strong dynamic pressure, the triaxial mechanical properties of mudstone samples under pre-cracking damage conditions were tested to study the deformation and failure characteristics and energy evolution mechanism in the damage process, under different loading rates and confining pressures. In the mechanical experiment, the specimen is pre-cracked to simulate the damage and failure of surrounding rock during roadway excavation, and the damage degree model of rock specimen is established. The results show that the loading rate and confining pressure have significant effects on the peak strength and energy characteristics of mudstone at the average damage degree of 0.12, and the peak strength increases with the increase in confining pressure and loading rate. Under the same confining pressure, the energy increases first, and then decreases with the increase in loading rate, and the loading rate at the turning point is called the critical loading rate. Under the same confining pressure, the closed stress of mudstone gradually increases with the increase in loading rate, and the closed stress and loading rate show a good linear relationship. Through the fitting relationship, it is found that the fitting correlation coefficient between the closed stress of mudstone and the loading rate is as high as 0.99. The elastic strain energy ratio presents a composite function of exponential function with natural constant e, which is a nonlinear process

Instability mechanism and control technology of soft rock roadways affected by mining in karst mountain area

Abstract The deformation and damage of soft rock roadways in karst mountainous area is serious, which greatly restricts the safe and efficient mining of coal resources. To explore the instability mechanism of soft rock roadway under the influence of mining, the 226 rail cross-cut of Shanjiaoshu Coal Mine in China was taken as an engineering background. The methods of field monitoring and drilling imaging were adopted to analyze the roadway failure characteristics. In addition, the distributions of the plastic zone, surface displacement, and fracture fractal evolution characteristics of the surrounding rock for different stress wave peak and stress wave frequency are compared and analyzed using UDEC software. Then, the combined support scheme of “secondary strong bolting and grouting” is proposed to control the severe deformation of the roadway. The primary support mainly adopts short hollow grouting anchor cable to strengthen the shallow broken surrounding rock within 0–3 m. The secondary reinforced support adopts long hollow grouting anchor cable or constant resistance large deformation anchor cable to fully mobilize the bearing capacity of deep surrounding rock and to ensure the long-term stability of the roadway. On-site monitoring showed that the scheme could effectively control the severe deformation of the roadway, which also provided a reference for other similar roadway support

Preparation and Characterization of Bletilla striata Polysaccharide/Polylactic Acid Composite

Polylactic acid (PLA) is limited in its application due to its high price, high brittleness and low glass-transition temperature. Modification methods are currently used to overcome these shortcomings. In this study, Bletilla striata polysaccharide (BSP) was blended with PLA by a solvent method. DMA data showed that the BSP/PLA film had a higher glass-transition temperature, and the glass-transition temperature of the film showed an extreme value of 68 °C when the proportion of the chalk polysaccharide was 0.8%. TG data indicates that the composite film material has good thermal stability. Tensile tests show that the composite film is improved in rigidity and elasticity compared to the pure PLA film. The blending modification of PLA with white peony polysaccharide not only reduces the cost of PLA, but also improves the thermal and mechanical properties of PLA

Monolithic integration of three-material microelectrodes for electrochemical detection on PMMA substrates

Monolithic integration of three-material microelectrodes for electrochemical detection on poly (methyl methacrylate) (PMMA) substrates is presented. Au–Ag–Pt three-material electrodes were all fabricated based on polymer compatible photolithography processes, and the fabrication sequence of the electrodes was optimized. The C–Ag–Pt three-electrode system was also demonstrated. To reduce the electrical resistance, the carbon electrode was made on a silver intermediate layer which was simultaneously fabricated with Ag electrodes. A PMMA/poly(dimethylsiloxane) electrochemical sensing microchip with the Au–Ag–Pt three-electrode systems was constructed. The reproducibility of the three-electrode system from single and different microchips was characterized. The performance of the microchip was evaluated by two kinds of electrochemical probes (Ru(bpy)3Cl2 and dopamine). Keywords: Microelectrode, Microchip, Electrochemical detection, PMM

The Transition of Mg-Containing Phases and Recovery of NaCl in Molten Salt Chloride Slags at High Temperature

The molten salt chlorination method is more suitable to produce TiCl4 using titanium-containing materials with high contents of CaO and MgO in China. However, there is a large amount of molten salt chloride slags generated from the molten salt chlorination process, which contains a variety of chlorides and is difficult to treat, often causing serious environmental problems such as direct piling or landfilling. A novel process was proposed to deal with molten salt chloride slags, and calcium chloride could be effectively removed by this process (as in our previous study). However, magnesium chloride is another impurity which can deteriorate the density and viscosity of the molten salt; it is often found in higher contents, and should be also removed from molten salt chloride slags to efficiently recycle NaCl in novel processes. Na2SiO3 is added to the molten salt chloride slags in the molten state to produce the Mg-containing solid phase, which could be separated with the molten NaCl in novel processes. Thus, the transition of Mg-containing phases and the recovery of NaCl in molten salt chloride slags at high temperature in a novel process were systematically investigated in this work, including thermodynamic analysis, the phase transition behavior of Mg-containing phases, NaCl recovery, etc. The removal rate of Mg was 99.56% when the molar ratio of MgCl2:Na2SiO3 was 1:1.5 at 1273 K and in a N2 atmosphere. The recovery rate of NaCl from the molten salt chlorination slag was 97.62% and the purity of NaCl obtained was 99.35 wt%, which could be used in the molten salt chlorination process