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Due to the influence of many factors, the overpressure–time history load model of vented gas explosions is difficult to describe and is not conducive to further structural design. Based on vented gas explosion test data, this paper obtains three typical overpressure-time history curves and puts forward a new semi-empirical model— double hump model that considers gas concentration and venting pressure, and gives a formula for peak pressure and overpressure–time history model. The scientificity of the model is then verified by the total impulse in the load. The model is able directly reflect the load characteristics, provide reference for calculating key parameters of a vented gas explosion and provide information on the structural response under the load. The model thereby has the potential to help reduce the impact of gas explosion disasters.

To provide information concerning quantitative risk analysis of gas-storage caverns, it is vital to estimate the hazard area of dispersion caused by accidental leakage. The Gaussian plume model is selected to calculate the hazard area caused by continuous leakage; the method of analysis is validated using wind-tunnel experiments of acetylene. Fluent is used to simulate the hazard area of dispersion caused by instantaneous leakage; the method of numerical simulation is verified by Burro/Coyote trials. Furthermore, a sample underground gas-storage cavern in salt rock is examined with respect to the toxic threshold limit value and the upper and lower flammability limits. In doing so, the factors that influence the hazard range of dispersion from salt cavern are discussed. The results indicate that the hazard area decreases with an increase in wind speed and a decrease in atmospheric stability when the leakage is continuous. However, the hazard area decreases with a decrease in wind speed when leakage is instantaneous.

Liquefied natural gas (LNG) leaks often lead to cascading accident disasters, including vapor cloud release, explosion, fire, and toxic gas release. The origin and evolution of each accidental disaster must be considered when assessing safety. This paper discusses the safety assessment project of an LNG gas storage station in Xuzhou, China. Multiple conceivable disasters due to the leakage of LNG storage tanks are simulated and analyzed using the computational fluid dynamic software FLACS. We studied different wind speeds interacting with the flammable vapor cloud area and creating frostbite in areas of low temperature. Diffusion simulations of vapor cloud explosion (VCE), thermal radiation, and the distribution of toxic substances were performed. The overpressure-impulse criterion was used to calculate the influence range of VCE. Heat flux, heat dose, and heat flux-heat dose criteria were used to calculate the safe distance for personnel in the event of fire. Based on the calculation results of the three latter criteria, this paper recommends using the heat flux criterion to evaluate fire accidents. The danger zone of each accident was compared. VCE accidents yielded the largest area.

A total of 16 full-scale in-situ tests were carried out to investigate the performances of unreinforced clay brick masonry walls subjected to vented gas explosions. The pressure-time histories of vented gas explosions, displacement-time histories and failure modes of wall specimens in each test were recorded and analyzed. A detailed micro model for masonry wall was developed in the finite element software LS_DYNA 971. The numerical model was validated with the test data and intensive numerical simulations were conducted to explore the influences of boundary condition, bonding pattern and thickness of masonry walls on their performances against vented gas explosions. The results show that the classical yield-line modes dominate failure patterns of masonry walls subjected to vented gas explosions and the dynamic responses of masonry walls are determined by the peak value of overpressure. It is found that boundary condition and wall thickness have great influence on the performance of masonry walls, while bonding pattern has relatively limited influence on its performance. In addition, the recorded gas explosion loads were compared with the predictions from the conventional TNT equivalency method and the methods specified in NFPA 68 and EN 14994. The results indicate both NFPA 68 and EN 14994 approaches give very conservative predictions of peak pressure from gas explosions. The TNT equivalency method also overestimates the peak pressure and predicts a load profile which is significantly different from the test data.

9 batches of unconfined methane-air deflagration tests were conducted to investigate the influential factors on the deflagration load. The methane-air mixture was filled in the cubic tents with different volumes of 1 m3, 8 m3and 27 m3. Methane concentrations varied from 7.5% to 11.5%, covering both lean and rich combustion regimes. The ground overpressure was recorded by using the piezoresistive sensors. An ideal film was validated before the tests. The effects of the methane concentration and gas volume on the deflagration load were analyzed. Based on the results, a new prediction model for the unconfined methane-air deflagration load was proposed. In addition, the model was compared with some existing models.

Hydraulic fracturing is an effective technology to improve shale gas wells production. The key problem in shale gas well hydraulic fracturing is opening hydraulic fractures to connect natural fractures and weak planes, in turn, creates the fracture network. The shear failure of matrix, natural fracture and weak plane are the main rock rupture models used in shale gas reservoirs. In this paper, firstly, a bottom hole pressure calculation model is built to show that large hole perforations and big pipeline diameters should be used to decrease perforation friction. Secondly, shale rock, natural fracture and weak plane shear failure models, based on rock mechanics theory, are presented. The calculated results show that horizontal differential principal stress has a significant influence on shear failure and the slippage of natural fracture and weak plane. A higher value of differential principal stress indicates a lower shale rock shear failure pressure, which brings benefits to weak plane slippage. Elastic modulus and Poisson's ratio all have effects on weak plane shear slippage. The influences of elastic modulus on shear slippage have a greater impact than Poisson's ratio. A reasonable dip angle of weak plane is also provided to enhance weak plane slippage. The practical-approach built in the paper does not require more rock mechanics parameters. The results have potential to enrich shale rock shear rupture theory and benefit fracture mesh system research.

In order to study the dynamic response characteristics and anti-deformation ability of different architectural glass under the action of gas explosion, four types of architectural glass, namely tempered glass, laminated glass, hollow glass and float glass, were selected as test samples. The explosion test is carried out by changing the thickness of the glass specimen, the gas concentration and the explosion venting material and other factors under the condition of fixed support on four sides. The results show that different types of architectural glass have different anti-explosion capabilities, so the failure mode and crack distribution under the action of gas explosion are different. With the increase of the thickness of the structure layer, the anti-explosion ability of different building glasses is improved. When the concentration of methane is close to the stoichiometric concentration or the strength of venting material is higher, the dynamic response of the glass specimen is more violent and even destroyed. At the same time, the finite element software LS-DYNA was used for numerical analysis of the single-layer glass test model. The failure mode and crack distribution obtained were basically consistent with the test results, which verified the reliability of the numerical simulation method.

The high-speed flying debris from architectural glass in a gas explosion poses a great security threat to personnel and building safety. In this paper, the damage characteristics of float glass under gas explosion venting loads and the distribution of glass fragments are studied through field tests. The results show that the rupture and dispersion of float glass are affected by the glass thickness and type and the methane concentration. Float glass exhibits spider-web cracking, and the fragments are sharp. The main shape of the debris dispersion front is either rectangular or “drum” shaped. The initial ejection speed of the shards is affected mainly by the glass thickness. The flying debris undergoes different acceleration and deceleration processes, and two acceleration peaks occur for a methane concentration of 9.5%. The glass shards are concentrated in two main areas of the collection site, and a theoretical model of glass scattering is established based on the test results. It can provide basic experimental data for research into gas explosions and act as a reference for the anti-explosion design of building structures.

29 batches of vented explosion tests were conducted in a 12 m 3 concrete chamber filled with methane–air mixtures to investigate the effects of methane concentration and venting pressure on the development of overpressure inside the chamber. The deflagrations were vented from a square side window with a venting area of 0.64 m 2 upon rupture of the vent cover. The venting pressures were varied by using six different types of vent covers, and determined by performing a numerical simulation. Methane concentrations in the mixed gas varied between 6.5 and 13.5 vol.%, covering both lean and rich combustion regimes. The generation conditions of the four types of overpressure–time profiles with different overpressure transients were summarized. Among the overpressure transients, the Δ P 1 caused by failure of the vent cover and the Δ P 4 resulted from the coupling between acoustic mode and flame were basically dominant. The rate of Δ P 1 rise as well as peak value of Δ P 1 and Δ P 4 showed a same trend of first increasing and then decreasing with the methane concentration from lean to rich. They reached their maximum value at the methane concentration of about 9.5%, whereas the rate of Δ P 4 rise was found to be insensitive to the methane concentration. The peak value of Δ P 1 increased with the venting pressure, while that of Δ P 4 first increased and then decreased as the venting pressure increased. In addition, the rates of Δ P 1 and Δ P 4 rise were both insensitive to the venting pressure. The occurrence of Δ P 4 was depended on the methane concentration and the venting pressure. The differences in the behavior of these overpressure transients suggest their different generation mechanisms.

Glass curtain walls are widely used in modern architectural design, the majority, of which are built using laminated glass. Shattering of these glass walls during natural gas explosions caused by accidental leakages create hazardous glass shards. This work therefore experimentally investigates the dynamic response of laminated glass during a gas explosion by varying the methane concentration, vent closure material, glass layer thickness, and PVB interlayer thickness. The results indicate that the closer the gas concentration is to 9.5%. The use of a stiffer venting material venting also caused a greater displacement of the glass, thus decreasing its resiliency. The PVB interlayer can bond the glass fragments together to restrain the flying effect. Furthermore, increasing the thickness of the glass, and PVB clamp layers improved the ability of the specimen to resist the gas explosion loads. These test results provide a reference for the design of explosion-resistant laminated glass design and accident prevention.

Nanofiltration membrane with high water permeability and anti-fouling nature is particularly needed to be explored in dyeing wastewater treatment. Herein, a hydrophilic calcium carbonate/polyethyleneimine-gallic acid (CaCO3/PEI-GA) loose NF membrane was prepared via a layer assembled in-situ mineralization (LAIM) strategy. This strategy endowed the membrane with the following advantages: the formation an ultrathin CaCO3/PEI-GA selective layer with a thickness of 76 nm and the highly enhanced surface hydrophilicity due to in-situ formation of CaCO3 nanoparticles. As a result, the prepared CaCO3/PEI-GA loose NF membrane showed 154% higher water flux (48.5 L/(m2 h bar) vs. 19.1 L/(m2 h bar)) compared with the control polyethyleneimine-gallic acid (PEI-GA) loose NF membrane for 100 mg/L Congo red (CR) solution, with equivalent rejection (99.6% vs. 99.7%). Moreover, this membrane also displayed outstanding anti-fouling ability, i.e. flux recovery ratio (FRR) of 94.9% for 1000 mg/L humic acid (HA) solution, and excellent performance stability in separation of dye/salt (CR/NaCl) aqueous solution for 60 h. The aforementioned advantages of the CaCO3/PEI-GA loose NF membrane indicate its promising application in dyeing wastewater treatment.

Background/Aims: This study aimed to report the clinical efficacy of continuous renal replacement therapy (CRRT) in combination with ultrasound-guided percutaneous transhepatic gallbladder drainage (PTGD) (CRRT+PTGD) in the treatment of acute severe biliary pancreatitis (ASBP). Methods: Between January 2010 and January 2016, 40 cases of patients with ASBP who received routine CRRT (CRRT group) and 40 of those who received CRRT+PTGD (CRRT+PTGD group) at the Affiliated Hospital of Qingdao University (Qingdao, China) were retrospectively reviewed. Clinical (including abdominal pain remission time, gastrointestinal decompression time, Intensive Care Unit (ICU) hospital stay, respirator treatment time, and mortality rate), laboratory (white blood cells [WBC], platelet [PLT], procalcitonin [PCT], C-reactive protein [CRP], total bilirubin [TBIL], alanine aminotransferase [ALT], albumin [ALB], and blood lactic acid [Lac]) parameters, various critical disease scores, and incidence of complications after the treatment were compared between the two groups. Results: Compared with those in the routine CRRT group, patients in the CRRT+PTGD group exhibited significant remission of clinical symptoms (i.e. shorter abdominal pain remission time, gastrointestinal decompression time, respirator treatment time and ICU hospital stay) (all PConclusion: CRRT in combination with PTGD is more effective in the treatment of ASBP than CRRT alone.

Linalool oxide is an aroma material found naturally in apple, bitter orange peel oil, raspberry, beer, brandy, tea, pear, brandy, and other plants. A variety of production of linalool oxide has been reported. We report a new method for the chemical synthesis of furanoid linalool oxide from 3,7-dimethyl-2,6-octadienal in this paper. A short and efficient synthesis of furaniod linalool oxide was accomplished in five steps from 3,7-dimethyl-2,6-octadienal which was underwent epoxidation, acid rearrangement, NaBH4 reduction, the selectively protection of resulting hydroxyl, and the elimination reaction. The GC content was 98%. The over yield was 52.84%. All of the intermediates and products were characterised by IR, NMR and MS.

It is very important and necessary to perform quantitative hazard analysis for possible accidental leakage from an underground gas storage cavern in salt rock. An integrated quantitative hazard analysis method for natural gas jet release from salt caverns is presented in this paper, which was constituted by a revised model for gas leakage rate calculation, a consequence analysis and a model of probability assessment for harm. The presented method was validated by comparing the analytical results with the data collected from the real accidents (including the leakage, jet fire, fireball and vapor cloud explosion). It is indicated that the proposed method was more accurate than the TNT equivalence method for vapor cloud explosion and gave more reasonable results when applied to the consequence analysis for the thermal radiation from jet fire and fireball.

It is of great importance and necessity to perform quantitative hazard analysis on possible accidental leakage from gas storage cavern in salt rock. To improve the working safety in the cavern, an integrated quantitative method for hazard analysis on natural gas jet release from caverns in salt rock was presented. In this paper, a sample of gas storage cavern in salt rock was analyzed to demonstrate the presented method. Furthermore, the factors that influence the hazard range of leakage accidents from gas storage cavern in salt rock were discussed. The results indicated that the release rate diminishes with increased pipe length due to friction in steady-state. Meanwhile, the hazard distance from production casing also diminishes with increased pipe length. As the pipeline gets as long as several kilometers, the predicted hazard distance will be constant. However, the hazard distance increases with increasing the operating pressure and pipeline diameter.

The effects of overpressure on different aspects of organic matter maturation have been examined in three basins using multiple parameters. Overpressure in the Yinggehai Basin has retarded kerogen maturation, hydrocarbon generation, and thermal cracking of long-chain normal hydrocarbons, as well as evolution of isoprenoid hydrocarbons. Overpressure in the Dongpu depression, Bohai Bay Basin, seems to have retarded the maturation of bulk kerogens reflected by Rock-Eval Tmax, the thermal cracking of long-chain normal hydrocarbons, and the evolution of isoprenoid hydrocarbons, but seems to have had no detectable effects on vitrinite reflectance. Overpressure in the Qiongdongnan Basin has had no detectable retardation effects on all aspects of organic matter maturation. The observed phenomena suggest differential retardation of organic matter maturation (that is, different organic matter maturation reactions and different maturity parameters have been retarded by overpressure to different degrees in the same overpressured system) and four hierarchies of overpressure retardation. Hierarchy I retardation is defined as the state where the overpressure has retarded all aspects of organic matter maturation and is proposed to have been caused by the combination of high formation pressure and excess pressure, a high-water/organic matter ratio, and strong retention of reaction products in an early-developed, strong, persistent overpressured system. Hierarchy II retardation refers to the case in which all aspects of organic matter maturation except the maturation of hydrogen-poor kerogens, especially vitrinite, have been retarded and seem to have been caused by early-developed, moderate to strong, persistent overpressure. Hierarchy III retardation refers to the situation where overpressure has retarded only the thermal cracking of liquid hydrocarbons, but has had no detectable effect on the maturation of both hydrogen-rich and hydrogen-poor kerogens, and is proposed to have been caused by moderate to strong, persistent overpressures that began to develop around peak oil generation. Hierarchy IV retardation is defined as the situation where overpressure has had no detectable retardation on all aspects of organic matter maturation and may have been caused by cases wherein the overpressure developed too late, the intensity of the overpressure was too low, the duration of the overpressure was too short, or overpressured fluids had been expelled frequently. Resulting from both the diversities of organic matter maturation reactions and the complexities of overpressure generation and development, the hierarchies of overpressure retardation in different basins may be quite different, and it is necessary to use multiple parameters to understand the evolution of the petroleum systems in overpressured basins.

Objective to investigate the expression of NF-κB and occludin in intestinal mucosal barrier during severe acute pancreatitis (SAP) and its clinical significance. Method Twenty-four Wistar rats were randomly divided into a normal control group, an SAP group, and a PDTC group. The rats were sacrificed at 24h after modeling, and general appearance of the abdominal cavity, pathological changes of the intestinal mucosa, changes in intestinal mucosal permeability were observed, serum inflammatory factor IL-1 was measured, and expression of tight junction protein occludin in the intestinal epithelial cells were determined by immunohistochemistry. Results Rats of the SAP group showed obvious inflammatory reaction in the abdominal cavity, manifested by enlargement of intestinal tract, intestinal edema, and increased permeability of intestinal barrier, whereas NF-κB inhibitor alleviated intestinal damage and intestinal mucosa edema, upregulated intestinal epithelial tight junction protein occludin, decreased intestinal permeability, and lowered the level of inflammatory factors. Conclusion Impairment of intestinal barrier function during SAP may be associated with increased NF-κB and decreased intestinal tight junction protein occludin; inhibiting NF-kB may alleviate intestinal mucosal barrier dysfunction during SAP.

The paper explores the possibility of using periodic precipitation to prepare anisotropic materials, on the basis of a numerical model of the time evolution and product distribution in periodic precipitates formed by competitive particle growth. The model envisages a pre-existing uniformly distributed material. After a time which depends on the sample length and other system parameters, a nearly stationary state is reached, in which the band spacings and masses, and the radii of individual particles are indeed much more uniform than they are in systems which depend primarily on reagent diffusion.