The impact of height on the spread of spinal anesthesia and stress response in parturients undergoing caesarean section: a prospective observational study

Background The spread of spinal anesthesia was influenced by many factors, and the effect of body height on spinal anesthesia is still arguable. This study aimed to explore the impact of height on the spread of spinal anesthesia and the stress response in parturients. Methods A total of ninety-seven parturients were allocated into two groups according to their height: the shorter group (body height was shorter than 158 cm) and taller group (body height was taller than 165 cm). Spinal anesthesia was performed with the same amount of 12 mg plain ropivacaine in mothers of different heights. The primary outcome of the study was the success or failure of the spinal anesthesia. The secondary outcomes of the study were stress response, time to T6 sensory level, the incidence of hypotension, the satisfaction of abdominal muscle relaxation and patient VAS scores. Results The rate of successful spinal anesthesia in the shorter group was significantly higher than that in the taller group (p = 0.02). The increase of maternal cortisol level in the shorter group was lower than that in the taller group at skin closure (p = 0.001). The incidence of hypotension (p = 0.013), time to T6 sensory block (p = 0.005), the quality of abdominal muscle relaxation (p < 0.001), and VAS values in stretching abdominal muscles and uterine exteriorization (p < 0.001) in the shorter group were significantly different from those in the taller group. Multivariate analysis showed that vertebral column length (p < 0.001), abdominal girth (p = 0.022), amniotic fluid index (p = 0.022) were significantly associated with successful spinal anesthesia. Conclusions It’s difficult to use a single factor to predict the spread of spinal anesthesia. Patient’s vertebral column length, amniotic fluid index and abdominal girth were the high determinant factors for predicting the spread of spinal anesthesia. Trials registration ChiCTR-ROC-17012030 (Chictr.org.cn), registered on 18/07/2017.

Analysis of Sub-Atmospheric Pressures during Emptying of an Irregular Pipeline without an Air Valve Using a 2D CFD Model

Studying sub-atmospheric pressure patterns in emptying pipeline systems is crucial because these processes could cause collapses depending on the installation conditions (the underground pipe covering height, type, fill, and pipeline stiffness class). Pipeline studies have focused more on filling than on emptying processes. This study presents an analysis of the following variables: air pocket pressure, water velocity, and water column length during the emptying of an irregular pipeline without an air valve by two-dimensional computational fluid dynamics (2D CFD) model simulation using the software OpenFOAM. The mathematical model predicts the experimental values of the study variables. Water velocity vectors are also analysed within the experimental facility, assessing the sensitivity of the drain valve to different openings and changes in water column length during the hydraulic phenomenon.

Anaerobic Degradation of Diesel Fuel Contaminated Wastewater in a Fluidized Bed Rector

This thesis studies the performance of the Anaerobic Fluidized Bed Reactor (AFBR) in treating diesel fuel contaminated wastewaters. The AFBR is a semi-cyclindrical fluidized bed, with a capacity of 300 L and height of 2.90 m with sampling ports along the column length. Granular activated carbon (12-20 mesh) was used as the medium to immobilize biomass. Diesel fuel was the sole source of carbon for microorganisms. The system's COD removal capability and diesel fuel removal efficiency were measured at 100 mg/L, 200 mg/L, and 300 mg/L influent diesel fuel in the reactor. Hydraulic Residence Time (HRT) varied for each set of experiments from 96 to 6 hours. The system achieved diesel removal efficiency of more than 84.1% for 300 mg/L influent diesel concentration for the maximum flowrate treated (1200 L/d) at a minimum HRT of 6 hours. This investigation confirms that anaerobic degradation of diesel contaminated water can be carried out very effectively in the AFBR.

Anaerobic Degradation of Diesel Fuel Contaminated Wastewater in a Fluidized Bed Rector

This thesis studies the performance of the Anaerobic Fluidized Bed Reactor (AFBR) in treating diesel fuel contaminated wastewaters. The AFBR is a semi-cyclindrical fluidized bed, with a capacity of 300 L and height of 2.90 m with sampling ports along the column length. Granular activated carbon (12-20 mesh) was used as the medium to immobilize biomass. Diesel fuel was the sole source of carbon for microorganisms. The system's COD removal capability and diesel fuel removal efficiency were measured at 100 mg/L, 200 mg/L, and 300 mg/L influent diesel fuel in the reactor. Hydraulic Residence Time (HRT) varied for each set of experiments from 96 to 6 hours. The system achieved diesel removal efficiency of more than 84.1% for 300 mg/L influent diesel concentration for the maximum flowrate treated (1200 L/d) at a minimum HRT of 6 hours. This investigation confirms that anaerobic degradation of diesel contaminated water can be carried out very effectively in the AFBR.

A prediction model using machine-learning algorithm for assessing intrathecal hyperbaric bupivacaine dose during cesarean section

Background The intrathecal hyperbaric bupivacaine dosage for cesarean section is difficult to predetermine. This study aimed to develop a decision-support model using a machine-learning algorithm for assessing intrathecal hyperbaric bupivacaine dose based on physical variables during cesarean section. Methods Term parturients presenting for elective cesarean section under spinal anaesthesia were enrolled. Spinal anesthesia was performed at the L3/4 interspace with 0.5% hyperbaric bupivacaine at dosages determined by the anesthesiologist. A spinal spread level between T4-T6 was considered the appropriate block level. We used a machine-learning algorithm to identify relevant parameters. The dataset was split into derivation (80%) and validation (20%) cohorts. A decision-support model was developed for obtaining the regression equation between optimized intrathecal 0.5% hyperbaric bupivacaine volume and physical variables. Results A total of 684 parturients were included, of whom 516 (75.44%) and 168 (24.56%) had block levels between T4 and T6, and less than T6 or higher than T4, respectively. The appropriate block level rate was 75.44%, with the mean bupivacaine volume [1.965, 95%CI (1.945,1.984)]ml. In lasso regression, based on the principle of predicting a reasonable dose of intrathecal bupivacaine with fewer physical variables, the model is “Y=0.5922+ 0.055117* X1-0.017599*X2” (Y: bupivacaine volume; X1: vertebral column length; X2: abdominal girth), with λ 0.055, MSE 0.0087, and R2 0.807. Conclusions After applying a machine-learning algorithm, we developed a decision model with R2 0.8070 and MSE due to error 0.0087 using abdominal girth and vertebral column length for predicting the optimized intrathecal 0.5% hyperbaric bupivacaine dosage during term cesarean sections.

Disaster Control of Roof Falling in Deep Coal Mine Roadway Subjected to High Abutment Pressure

The roof falling accident is a serious threat to the lives of miners in deep coal mining, especially when the coal mine is more than 1000 meters deep. In regard to the 5306 coalface in the Tangkou coal mine, Shandong, China, the depth of coal seam is 992.8 m and the stress concentration coefficient of the roadway surrounding rock is 3.33. This leads to a serious deformation of the roadway roof, thereby producing a high risk of the roof falling disaster. In this pursuit, based on the mechanical analysis of roadway roof subjected to a high abutment pressure, the mathematical expressions of the setting load and movable column length of supports were introduced. Furthermore, the stability control mechanism of the roadway roof was analyzed and the optimized support parameters of supports are provided. The results showed that the longtime effective support of the roadway roof required the strength and deformation coupling of supports and anchored surrounding rock. The support length of the belt roadway should be at least 57.7 m, with 0-30 m away from the coalface supported by hydraulic supports and 32-57.7 m supported by single props. In addition, the maximum setting load and movable column length of hydraulic supports were 21.67 MPa and 280.3 mm and 12.44 MPa and 177.1 mm for single props, respectively. By applying the optimized support parameters of supports to the belt roadway of the 5306 coalface, the effective control of the roadway roof and the disaster control of roof falling were realized.

Control of density and velocity of emulsion explosives detonation for ore breaking

Purpose.Development of a new procedure for calculating the density of emulsion explosives (EE), that will allow determining the detonation velocity along the charging length, depending on the inclination of boreholes during ore breaking. Methodology.A calculation method for the redistribution of EE density and mass in boreholes at different angles of inclination has been developed by using the well-known laws of hydrostatics. Measurement of the detonation velocity of the EE Ukrainit-PP-2B was conducted by using the method of polygon experimental tests. The numerical simulation of changes in the detonation velocity of explosives in boreholes was conducted by using the proposed method and established regularities. Findings.Methods of calculation of EE density changing along the charging column length under the action of hydrostatic pressure at different angles of inclination of both ascending and descending boreholes have been developed. Based on experimental data, regularities of detonation rate changing from density and charge diameter for EE Ukrainit-PP-2B, varying according to exponential law have been established. The rational initial density of EE Ukrainit-PP-2B has been established for ores breaking by boreholes, which is equal to 8001000 kg/m3, at which the detonation rate along the length of the charge column at different angles of inclination of the boreholes is maintained. The obtained results will allow controlling density and detonation velocity during ore breaking. Originality.The density of EE increases in the formed charging column under the action of hydrostatic pressure: in ascending boreholes from the face, while in descending boreholes from the brow. Practical value.Application of the calculation results of EE density at different inclination angles of boreholes makes it possible to determine in the charge column sections with its critical values more than 1410 kg/m3, at which a sharp attenuation of the detonation rate begins. Consideration of this phenomenon makes it possible to prevent the occurrence of failures at the explosion of charges in boreholes during ore breaking.

Pressure oscillation of an air pocket beneath a water column in a vertical riser

Storm geysers have received significant attention lately due to its more frequent occurrences and the induced severe local flooding and infrastructure damages. Previous studies suggested that the air pocket pressure oscillated during geyser events especially in rapid filling process, but only the peak values were studied and the oscillation period was not discussed in detail. In this paper, a theoretical model was developed focusing on the period of the pressure oscillation induced by the expansion/compression of the air pocket below a water column in a vertical riser with film flow. It was found that the oscillation period was a function of the initial air pocket volume, initial air pocket pressure head, the riser diameter, and the initial water column length. The oscillation period increased with the air pocket pressure head and the air pocket volume, but decreased with the riser diameter and the polytropic coefficient. The oscillation period increased then decreased with an increasing water column length. Further, when considering the film flow along the riser, the oscillation period decreased slightly from the analytical solution. It was also found that the inflow rate change did not significantly influence the oscillation period.