Vent Time Research Articles

Safety and efficacy of precision hepatectomy in the treatment of primary liver cancer

BackgroundThe aim of this study was to investigate the safety and efficacy of precision hepatectomy in the treatment of primary liver cancer.MethodsAn randomized controlled trial of 98 patients with primary liver cancer admitted to our hospital from February 2020 to February 2021 were analyzed for the study, and they were divided into 49 cases each in the control group (conventional hepatectomy) and the study group (precision hepatectomy) according to the different surgical methods. The surgical condition, complications and follow-up results of the two groups were counted, and the liver function and immune function of the two groups were observed before and 1 week after surgery.ResultsThe operation time, intraoperative bleeding, hospitalization time and anal venting time in the study group were less than those in the control group (P < 0.05). One week after surgery, AST, TBiL, ALT and ALB levels decreased, with in the study group significantly higher than those in the control group (P < 0.05); CD4+, CD3 + and CD4+/CD8 + levels were significantly higher in the study group (P < 0.05). The incidence of complications in the study group was significantly lower than that in the control group (P < 0.05). After 2 years of follow-up, the recurrence rate and mortality rate of the study group were lower than those of the control group (P < 0.05); the difference was not statistically significant when comparing the metastasis rate between the two groups (P > 0.05).ConclusionPrecision hepatectomy can effectively treat primary liver cancer with high safety and could be promoted in clinical practice.

Efficacy of the enhanced recovery after surgery protocol in operating room nursing of patients following single-port video-assisted thoracoscopic lung cancer surgery: A retrospective study.

This study assessed the efficacy of the enhanced recovery after surgery (ERAS) protocol in operating room nursing care for patients who underwent single-port video-assisted thoracoscopic lung cancer surgery. The study included 82 surgical lung cancer cases. The patients underwent single-port video-assisted thoracoscopic lung cancer surgery between April 1, 2021, and June 31, 2022. Of the 82 patients, 42 received nursing care under the ERAS protocol (experimental group) and 40 had routine nursing care (control group) in the operation room. Based on the 2 different nursing care approaches, the postoperative functional recovery efficacy, quality of life, postoperative complications, and psychological status were compared between the 2 groups. In our analysis, the mean anal venting time, average early out-of-bed time, the average time to liquid resumption, atelectasis, and pulmonary infection rate were significantly lower in the experimental group than in the control group (P < .05). The Self-Rating Depression Scale (SDS) and the Self-Rating Anxiety Scale (SAS) scores were also significantly lower in the experimental group than in the control group (P < .05). Other indicators were not significantly different between the 2 groups. Our results show that the implementation of an ERAS protocol in operating room nursing care is feasible and should be clinically applied. The ERAS protocol may enhance the recovery of patients who underwent single-port video-assisted thoracoscopic lung cancer surgery.

Development of a novel periodic venting-controlled membrane biofilm reactor for hydrogenotrophic denitrification: Process performance and microbial mechanism

The performance of anaerobic membrane biofilm reactor (MBfR) has long been underexploited due to the limited delivery of active gas to the biofilm on the close-end hollow fiber membranes (HFMs). Here, to establish a valid scheme for overcoming this obstacle, we coupled a denitrifying H2-based MBfR to an automatic venting unit for intermittently updating intramembrane gas, and a microsensor unit for investigating the H2 diffusion behavior. In short-term experiments, at the HFM length of 60 cm and H2 supplying pressure of 1.2 atm, the periodic venting strategy, in which the venting time and interval were set as 30 s and 17 min, respectively, was validated to be capable of improving the denitrification performance of H2-based MBfR. The results of long-term experiment show that compared to the conventional close-end operation, the around 50% increase in denitrification flux was achieved in the periodic venting-controlled system, which was found to be associated with the increased biofilm thickness and the evolution of denitrifying bacteria (DNB) and functional genes in the biofilm at the HFM distal end. Model outputs manifest that regardless of the HFM length, the biofilm regions with high DNB activity at the distal end were much narrower than those at the proximal end of the close-end HFMs; owing to the improved H2 delivery, the active biofilm region at the distal end of 60 cm HFM was significantly enlarged from 0–225 µm in the case of close-end operation to 0–450 µm in the venting-controlled system. The proposed periodic venting strategy opens a new avenue for the management of anaerobic MBfR.

A new approach: Laparoscopic right hemicolectomy with priority access to small bowel mesentery.

For laparoscopic right hemicolectomy, the intermediate approach is commonly employed. However, this approach possesses several disadvantages. In this study, we compare priority access to the small bowel mesentery and the intermediate approach. The clinical data of 196 patients admitted to the First Hospital of Chongqing Medical University for laparoscopic right hemicolectomy from January 2019 to January 2022 were retrospectively collected and divided into the small bowel mesenteric priority access and traditional intermediate access groups. The operative time, intraoperative bleeding, number of lymph node dissection, postoperative anal venting time, toleration of solid and liquid intake, and postoperative hospital stay and complications were compared between the two different approaches. In total, 81 cases of small bowel mesenteric priority access and 115 cases of intermediate approach for right hemi-colonic radical resection were compared. The operative time was 191.98 ± 46.05 and 209.48 ± 46.08 min in the small bowel mesenteric priority access and intermediate access groups, respectively; the difference was statistically significant. There were no significant differences in the intraoperative bleeding and lymph node clearance. However, the scatter plot analysis showed that severe intraoperative bleeding was relatively less frequent in the small mesenteric priority access group, compared with that in the intermediate approach group. Additionally, there were no statistically significant differences in the first exhaust and defecation times, hospital stay after operation, toleration of solid and liquid intake, and postoperative complication between the two groups. In laparoscopic right hemicolectomy, the small bowel mesenteric priority approach can significantly shorten the operation time compared with the intermediate approach. It can reduce intraoperative bleeding and the operation is simple and safe to perform, making it suitable for less experienced surgeons. Therefore, the small bowel mesenteric priority approach has the potential to be a suitable alternative and deserves further clinical promotion and application.

Simulation on venting process and valve opening control method for gas trunk pipelines

Determining the venting time of a gas trunk pipeline segment provides an important basis for formulating an emergency plan in the advent of unexpected accidents. As the natural gas venting process corresponds to the transient flow, it is necessary to establish a transient hydraulic-thermal simulation model in order to determine the venting time. In this paper, based on two kinds of venting scenarios in which there is only one venting point in the venting system of a gas trunk pipeline segment—namely, where the venting point is either at one of the two ends or at the junction of two gas trunk pipeline segments—transient hydraulic-thermal simulation models are established. The models consist of gas flow governing equations, the gas state equation, gas physical property equations, initial conditions, and appropriate boundary conditions. The implicit central difference method is used to discretize the gas flow partial differential equations, and the trust-region-dogleg algorithm is used to solve the equations corresponding to each time step, in order to dynamically simulate the whole venting process. The judgment condition for the end of the venting process is that the average pressure of gas trunk pipeline segment is less than 0.11 MPa (actual pressure). Comparing the simulation results of the proposed model with those of the OLGA software and real operational data, we find that the venting time error is less than 10%. On this basis, a venting valve opening control principle is proposed, which prevents the venting noise from exceeded the specified noise value (85 dB) in the venting design of domestic gas pipeline projects. The established calculation model for venting time (dynamic simulation model) for a gas trunk pipeline segment and the proposed opening control principle of venting valve provide reference for the optimal operation of gas pipeline venting systems.

X-ray computed tomography and simultaneous multi-signal detection for evaluation of thermal runaway of lithium-ion battery

ABSTRACT Early warning of thermal runaway (TR) scenarios is one of the most effective and important ways to prevent accidents in lithium-ion battery (LIB) safety management. Herein, TR characteristics of 18,650 LIB are carefully investigated using X-ray computed tomography (X-CT) and simultaneously multi-signal method. The results show that after the first gas venting, TR of LIB may not necessarily and spontaneously occur within a certain temperature range. The X-CT reveals that TR originally occurs in the central area along the axial direction of the LIB, and then it expands to the surface layer of the LIB during thermal abuse. Internal electric short circuit occurs at 100°C and structural damage occurs at 110°C. The first gas venting time is almost simultaneously as the first TR temperature rising, which provides a very effective way to anticipate early TR, guaranteeing enough time for handling of LIB accident and supplying chances for people escaping.

The Value of Combined Application of Oxycodone Hydrochloride Injection and Dexmedetomidine in Anesthesia for LC for Patients with Gallbladder Lesions.

Objective To analyze the effect of combined application of oxycodone hydrochloride injection and dexmedetomidine in anesthesia for laparoscopic cholecystectomy (LC) for patients with gallbladder lesions. Method 93 patients with gallbladder lesions in our hospital were divided into 2 groups by the random number table method. 46 patients in the control group applied oxycodone hydrochloride injection in anesthesia, and 47 patients in the observation group applied oxycodone hydrochloride injection combined with dexmedetomidine in anesthesia. Result The T1 and T2 MAP levels in the observation group were lower than those in the control group (P < 0.05), and the difference between T3 and the control group was not significantly significant (P > 0.05). The T1 to T3 HR level in the observation group were lower than those in the control group (P < 0.05). The rate of excessive sedation (10.64%) and sedation inefficiency (12.77%) in the observation group was lower than that in the control group (28.26% and 30.43%), and the rate of satisfactory sedation (76.60%) was higher than that in the control group (41.30%) (P < 0.05). The postoperative awakening, tracheal tube removal, and first anal venting time were shorter in the observation group than in the control group (P < 0.05). The WHO scores of incisional pain at 6, 12, 24, and 48 hours after the operation were lower in the observation group than in the control group (P < 0.05). The T2 SOD level in the observation group was higher than that in the control group, and the ROS and MDA levels were lower than those in the control group (P < 0.05). The incidence of side effects of anesthetic in the observation group was 17.02%, which was not statistically different from the control group of 13.04% (P > 0.05). Conclusion The combined application of oxycodone hydrochloride injection and dexmedetomidine in anesthesia for LC for patients with gallbladder lesions can achieve better sedation and analgesia effect, accelerate postoperative awakening and recovery, and control oxidative stress and fluctuations in signs, without increasing anesthesia-related side effects.

Patients should be extubated in the operating room after routine cardiac surgery: An inconvenient truth

Feature Editor's Introduction—Although 24-hour ventilator times have remained the quality metric for Society for Thoracic Surgeons (STS) Star rankings, it has become apparent over the past several years that the association between vent time and morbidity occurs much earlier.1 The reporting of a 6-hour metric for the past 20 years in the STS Adult Cardiac Surgery Database (ACSD) was a recognition of its benefits2 and pushed us to earlier extubations, such that ventilation time <6 hours has doubled since 2005, currently being accomplished in >60% of isolated coronary artery bypass grafting (CABG) surgeries (2017-20 ACSD Report).

High Purity Hydrogen Production by Metal Hydride System: A Parametric Study Based on the Lumped Parameter Model

The simulation of hydrogen purification in a mixture gas of hydrogen/carbon dioxide (H2/CO2) by metal hydride system was reported. The lumped parameter model was developed and validated. The validated model was implemented on the software Matlab/Simulink to simulate the present investigation. The simulation results demonstrate that the purification efficiency depends on the external pressure and the venting time. An increase in the external pressure and enough venting time makes it possible to effectively remove the impurities from the tank during the venting process and allows to desorb pure hydrogen. The impurities are partially removed from the tank for low external pressure and venting time during the venting process and the desorbed hydrogen is contaminated. Other parameters such as the overall heat transfer coefficient, solid material mass, supply pressure, and the ambient temperature influence the purification system in terms of the hydrogen recovery rate. An increase in the overall heat transfer coefficient, solid material mass, and supply pressure improves the hydrogen recovery rate while a decrease in the ambient temperature enhances the recovery rate.

Highly interconnected macroporous MBG/PLGA scaffolds with enhanced mechanical and biological properties via green foaming strategy

Abstract In this study, mesoporous bioactive glass particles (MBGs) are incorporated into poly(lactic-co-glycolic acid) (PLGA) to fabricate highly interconnected macroporous composite scaffolds with enhanced mechanical and biological properties via a developed supercritical carbon dioxide (scCO2) foaming method. Scaffolds show favorable highly interconnected and macroporous structure through a high foaming pressure and long venting time foaming strategy. Specifically, scaffolds with porosity from 73% to 85%, pore size from 120 μm to 320 μm and interconnectivity of over 95% are controllably fabricated at MBG content from 0 wt% to 20 wt%. In comparison with neat PLGA scaffolds, composite scaffolds perform improved strength (up to 1.5 folds) and Young's modulus (up to 3 folds). The interconnected macroporous structure is beneficial to the ingrowth of cells. More importantly, composite scaffolds also provide a more promising microenvironment for cellular proliferation and adhesion with the release of bioactive ions. Hopefully, MBG/PLGA scaffolds developed by the green foaming strategy in this work show promising morphological, mechanical and biological features for tissue regeneration.

Coupling of large volume injection with flow modulated two-dimensional gas chromatography

The coupling of large volume injection (LVI) with comprehensive two-dimensional gas chromatography (GC × GC) can be a powerful technique in the analysis of trace-level complex samples. The coupling of LVI and GC × GC using a cost efficiently operable pneumatic modulator based on capillary flow technology has been examined. The aim was to optimize the LVI parameters in the case of samples with compounds covering a wide boiling range. For the optimization of LVI 25 microliters of a solution containing 27 target compounds modelling the composition and the boiling range of diesel oils was used. The injection parameters were evaluated for peak shapes, reproducibility and peak volumes relative to peak volumes obtained using cold splitless injection. For all GC × GC experiments a non-polar first column (Rxi-5ms) and a polar second column (HP-INNOWax) were applied. Through extensive method optimization solvent vent proved to be an unsuitable technique for the injection of compounds covering a wide boiling range: at lower vent times peaks split, while higher vent times caused severe losses of highly volatile compounds. Therefore, a split-splitless LVI method was optimized. Injection speed, split vent time, splitless vent time and vent flow during split vent have been optimized. The developed method is suitable for the coupling of LVI with flow modulated GC × GC. Using the optimized split-splitless LVI parameters no peak distortion of the target compounds was observed. The relative peak volumes were between 60–120% for all compounds (80–120% for 13 compounds).

高压天然气站场放空时间的模型及其优化

高压天然气站场放空时间的模型及其优化

Analysis of clinical effect on 19 cases of inguinal hernia treated by laparoscopic totally extraperitoneal repair

Objective To investigate the effect of laparoscopic total extraperitoneal tension-free hernia repair (TEP) in the treatment of inguinal hernia with absorbable biological mesh. Methods A retrospective analysis of the clinical data of 19 patients with inguinal hernia with biological mesh was performed from September 2015 to September 2016 in Shengjing Hospital of China Medical University. The average operative time, average incision pain time, average postoperative venting time, average hospital stay, average operative cost, and long-term chronic pain, postoperative complications, and recurrence rate were observed. Results All the 19 patients were successfully operated. The average operation time was (35.0±4.0) min, the average incision pain time was (1.5±0.6) d, and the average postoperative venting time was (1.5±1.2) d. The average hospital stay was (4.5±0.9) d, the average surgery cost was (23 534.6±1 259.9) yuan. Two patients developed swelling of the scrotum after surgery, and one patient developed postoperative fat liquefaction. All patients were followed up for 1 year by telephone, with no recurrence, no serious complications, and chronic pain discomfort. Conclusions The application of absorbable biopsy TEP is a good and reliable way to treat inguinal hernia. Postoperative patients have mild pain and low complication rate. There is no recurrence in recent follow-up, and the short-term effect is satisfactory. It is a reliable method for the treatment of inguinal hernia. The cost is high, and can be selected according to age and individual needs. Key words: Hernia, inguinal; Laparoscopes; Laparoscopic totally extraperitoneal repair; Biological mesh; Tension-free repair

Determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in human serum using programmable-temperature vaporization gas chromatography with high-resolution mass spectrometry.

The determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in blood from a non-occupational population is essential for the investigation of adverse health effects from these pollutants. In this study, a sensitive method based on programmable-temperature vaporization with large-volume injection coupled with gas chromatography with high-resolution mass spectrometry was developed to determine these pollutants in 1-2mL of human serum samples. Various key parameters of programmable-temperature vaporization injector, including vent temperature, vent time, vent flow, transfer temperature and transfer time were optimized by factorial design. The accuracy and precision as well as applicability were assessed by determining polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in calibration standard solutions, standard reference materials and real human serum samples from non-occupational population. The method detection limits of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls were 1.5-9.0 and 0.005-0.02ng/kg wet weight, respectively. By comparing with typically splitless injection, the application of programmable-temperature vaporization injector could effectively lead to higher detectable rate of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in 1-2mL of human serum samples.

Effect of intravenous infusion with lidocaine on rapid recovery of laparoscopic cholecystectomy

Objective: To investigate the effect of intravenous infusion with lidocaine on rapid recovery of laparoscopic cholecystectomy. Methods: This study was a prospective randomized controlled trial. From February to August 2016 in Affiliated Yiwu Hospital of Wenzhou Medical University, 60 patients scheduled for laparoscopic cholecystectomy under general anesthesia were involved and randomly divided into control group (n=30) and lidocaine group (n=30). Patients in lidocaine group received lidocaine 1.5 mg/kg intravenously before induction and followed by 2.0 mg·kg(-1)·h(-1) to the end of surgery. Patients in control group received equal volumes of saline intravenously. Anesthesia induction in both groups were given intravenous midazolam 0.03 mg/kg, sufentanil 0.2 μg/kg, propofol 2.0 mg/kg and cisatracuium 0.2 mg/kg. Anesthesia was maintained with propofol 0.05-0.20 mg·kg(-1)·min(-1) and remifentanil 0.1-0.5 μg·kg(-1)·min(-1) for laryngeal mask airway which bispectral index (BIS) value maintained at 40-60. BIS, heart rate(HR) and mean arterial pressure(MAP) were recorded before anesthesia induction, before and immediately after laryngeal mask implantation, intraoperative 30 min and anesthesia awake. Pain scores were assessed using visual analogue scales (VAS) at postoperation immediately, 30 min during postanesthesia care unit (PACU), 2, 6, 12, and 24 h after surgery. The time of PACU retention, postoperative ambulation, first intestine venting and discharge were recorded. The dosage of propofol and remifentanil, the frequency of sufentanil used, the incidence of postoperative nausea and vomiting were also recorded. Patient satisfaction was evaluated by using Simple Restoration Quality Score (QoR-9). Results: BIS values before and after laryngeal mask implantation in lidocaine group were 50.50±3.47 and 54.63±1.25 respectively, which was lower than those in control group(54.30±4.78, 55.80±2.33; t=3.542, 2.423, all P<0.05). The VAS score at postoperation immediately, PACU 30 min, postoperative 2, 6, 12 h in lidocaine group were 2.76±0.97, 2.37±0.93, 2.10±1.12, 1.76±0.97, 1.20±0.76 respectively, which was lower than those in control group (3.83±1.34, 3.27±1.26, 3.06±1.20, 2.63±0.88, 1.90±0.84; t=3.528, 3.154, 3.217, 3.603, 3.372, all P<0.05 ). The frequency of additional sufentanil at postoperation immediately and PACU 30 min in lidocaine group was 5(17%), 3(10%), which were less than those in control group(12(40%), 9(30%); χ(2)=4.022, 3.950, all P<0.05). The dosage of propofol and remifentanil in lidocaine group were (4.33±0.75) mg·kg(-1)·h(-1) and (9.00±1.66) μg·kg(-1)·h(-1) respectively, which were less than those in control group ((5.20±1.39) mg·kg(-1)·h(-1) and (10.43±2.20) μg·kg(-1)·h(-1;) t= 2.982, 2.842, all P<0.05). The time of PACU retention, postoperative ambulation and first intestine venting were (39.90 ± 8.06) min, (11.93±1.68) h and (10.16±1.05) h respectively in lidocaine group, which were shorter than those in control group ((48.23±10.04) min, (13.16±1.58) h and (11.13±1.30) h; t=3.514, 2.931, 3.156, all P<0.05). The QoR-9 score in lidocaine group was 15.60±1.07, which was higher than that in control group(14.73±0.74, t=-3.649, P<0.05). There was no significant difference in the incidence of postoperative nausea/vomiting and the discharge time between two groups (all P>0.05). Conclusion: Intravenous infusion of lidocaine can effectively reduce the dosages of propofol and remifentanil, postoperative early VAS score, postoperative ambulation time and first intestine venting time which could improve the satisfaction of patients.

Focused ultrasound solid–liquid extraction for the determination of organic biomarkers in beachrocks

Beachrocks are consolidated coastal sedimentary formations resulting mainly from the relative rapid cementation of beach sediments by different calcium carbonate polymorphs. Although previous works have already studied the elemental composition and the mineral phases composing these cements, few of them have focused their attention on the organic matter present therein. This work describes an extraction methodology based on focused ultrasound solid–liquid extraction (FUSLE), followed by analysis using large volume injection (LVI) in a programmable temperature vaporizer (PTV) combined with gas chromatography–mass spectrometry (GC–MS) in order to determine organics such as polycyclic aromatic hydrocarbons (PAHs) and biomarkers (hopanes), which can increase and confirm the information obtained so far. This goal has been achieved after the optimization of the main parameters affecting the extraction procedure, such as, extraction solvent, FUSLE variables (amplitude, extraction time and pulse time) and also variables affecting the LVI–PTV (vent time, injection speed and cryo-focusing temperature). The developed method rendered results comparable to traditional extraction methods in terms of accuracy (77–109%) and repeatability (RSD<23%). Finally, the analyses performed over real beachrock samples from the Bay of Biscay (Northern Spain) revealed the presence of the 16 EPA priority PAHs, as well as some organic biomarkers which could increase the knowledge about such beachrock formation.

Effects of Inlet Location on Inert Replacement Efficiency of the Gasoline Vapor in Oil Tank

Elimination gasoline vapor in oil tank by mechanical ventilation has disadvantages of long vent time poor safety, and low efficiency, however, those shortcomings can be better conquered if combusted gas is used in the process of the mechanical ventilation. Based on former studies, the research on the effects of inlet location on gasoline vapor’s inert replacement in oil tank by combusted inert gas is studied experimentally in this paper. The conclusions in this paper can provide some useful guidance for the field project of gasoline vapor’s inert replacement in oil tank.

In-port derivatization coupled to different extraction techniques for the determination of alkylphenols in environmental water samples

Large volume injection (LVI)-in port silylation coupled to gas chromatography–mass spectrometry (GC–MS) for the determination of alkylphenols (APs) in water samples applying four different extraction approaches was evaluated. Among the variables studied for in-port derivatization, vent time, cryo-focusing temperature and the ratio solvent volume/N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) volume were optimized using an experimental design approach. Regarding the extraction techniques, different approaches previously optimized in the research group were tested. On the one hand different polymeric materials were tested: silicon rod (SR), polyethersulfone (PES) and polydimethylsiloxane (PDMS), the latter in the stir-bar sorptive extraction format (SBSE–PDMS). PES was chosen among the polymeric materials due to the higher recoveries (compared with SR) and lower price (compared to PDMS in the stir-bar sorptive extraction, SBSE–PDMS). Both MASE and PES protocols were selected at this point for further method validation and application to real samples. Finally, the developed methods were validated and applied to the determination of target analytes in various aqueous environmental matrices, including estuarine water and wastewater. Acceptable repeatability in the case of MASE (5–17%) and PES (7–21%) procedures and method detection limits (MDLs, 5–123 and 28–328ngL−1 for PES and MASE, respectively) were obtained for most analytes. In terms of apparent recoveries in the presence of matrix, estuarine and effluent samples showed no significant matrix effect (apparent recoveries in the 73–121% for PES and 74–128% for MASE), while a stronger matrix effect was observed for influent wastewater samples (98–132% for PES and 65–156% for MASE). Both MASE and PES extractions combined with LVI-in-port derivatization–GC–MS were applied to the determination of APs in the estuary of Bilbao (Gulf of Biscay, Spain).

Preparation and characterization of polystyrene foams from limonene solutions

The foaming process has been traditionally performed at high temperature because the CO2 and the polymer should behave as a homogeneous solution. The addition of a solvent could avoid the high working temperature while the homogeneity is ensured. Among the terpene oils, limonene outlines as a good candidate to carry out the dissolution of polystyrene because it respects the green chemistry principle, it is highly soluble in CO2 and very compatible with the polymer.The sorption of CO2 is the first step of the foaming process. The presence of the terpene oil enhances the solubility of the gas which is solubilized in the Polystyrene as well as in the limonene. During the foaming process, many parameters can be tuned to customize the foams. In this work, a fractional factorial design of experiment was proposed to determine the effect of pressure, temperature, concentration of the solution, contact time and vent time over the diameter of cells, its standard deviation and the cells density. The proposed foaming process can be simply performed at mild pressure and temperature thanks to the presence of the solvent. The results showed that the most suitable conditions to foam polystyrene from limonene solutions are 90bar, 30°C, 0.1gPS/ml Lim, 240min contacting and 30min venting. Finally, the samples were characterized to determine the amount of residual solvent, their glass transition and degradation temperature checking that the foams presented around 5% of solvent traces but did not show any evidence of degradation.

Research of Emergency Venting Time in Natural Gas Pipeline Accidents with SPS

Gas venting is an important step in the emergency repair of natural gas pipeline accidents. Accurately estimating the gas venting time is of great significance for arranging gas pipeline emergency repair process. Therefore, the venting model is built with Stoner Pipeline Simulator (SPS), and the influencing factors of venting time are studied by SPS dynamic simulation. The results show that pipe length, pipe pressure, pipe diameter and diameter of gas venting pipe can affect the gas venting time. And then a empirical law of natural gas venting time and pipe parameters is summed up, which can provide theoretical support for the organization of emergency repair.