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In alkaline in-situ leaching uranium, oxygen is the most common oxidizer with bicarbonate as a complexing agent. For those sandstone uranium deposits with strongly reductive capacity or complicated hydrogeological environment, the oxidation by oxygen is low efficiency. An efficient leaching method, therefore, is needed for these uranium deposits. In this study, a typical sandstone uranium deposit which characterizes with high TDS and high chloride content in groundwater and intractable uranium leach is selected to investigate the effects of synergetic oxidation by a strong oxidant with oxygen. Based on the research on batch leach, pressure leach and field trials, the oxidants such as hydrogen peroxide, potassium permanganate and sodium dichloroisocyanurate (NaDCC) are tested. The results of pressure batch leach indicate that synergetic oxidization is achieved by NaDCC in oxygen leaching process. Leaching tests indicate that a minor oxidizer of NaDCC shows good synergetic oxidization with oxygen and leaching effects on uranium minerals. The results also demonstrate that hydrogen peroxide shows no oxidation effects when it is used as a single oxidant. While potassium permanganate shows good oxidation on uranium when it is used as a single oxidant, however, it leads inhibiting effects on oxygen oxidation on uranium minerals. The further field tests are conducted to study the synergetic effects of oxygen with and without sodium dichloroisocyanurate. The preliminary results indicate that a fast leach is observed by the composite oxidants in early stage while no synergetic leach is found after 200 days. Further studies should be conducted in laboratory experiments and pilot scale tests for its potential applications.

In this study, catalyst formation [Pb(H2O)6][ATZ]·H2O (ATZ = azo tetrazolium anion) was successfully synthesized originally; meanwhile, the single-crystal structure of the compound was cultivated and analyzed by diffraction single-crystal method. The influence of the compound in which [Pb(H2O)6][ATZ]·H2O was used as combustion catalyst on the decomposition temperature of potassium nitrate was studied by TG–DSC. The result proved that [Pb(H2O)6][ATZ]·H2O can effectively reduce the decomposition temperature. In other words, [Pb(H2O)6][ATZ]·H2O can reduce the decomposition temperature of potassium nitrate, so the addition of [Pb(H2O)6][ATZ]·H2O can make potassium nitrate better to be used in the fields of initiating explosive device and fire engineering.

The objective of this study is to investigate the impact of different fractions (0–0.05) of C6F12O addition on laminar flame speed of hydrocarbon syngas by varying the fuel/oxidizer equivalence ratio (0.6–1.2) using Bunsen burner method. The determination of the syngas composition comes from the venting gas of lithium-ion cell during thermal runaway. It is found that C6F12O is significantly more effective at stoichiometric and fuel-rich conditions compared to lean flames regardless of fuel species, which implies more suitable for syngas/air flame inhibition than CH4. The laminar flame speeds of syngas/air increased with lower concentration (

A novel environmental-friendly unpacking powder for fireworks which has no sulfur, no magnesium, no aluminum or their alloys has been prepared in this study: potassium perchlorate (75%), potassium hydrogen terephthalate (13%), micronano porous silicon (9%), carbon (2%), ferrocene (1%). The PM2.5 and PM10 were collected by the ambient air particulate sampler, and the gas product was tested with a smoke analyzer and gas chromatograph to investigate its environmental-friendly performance. The detonation radius was measured by similar triangulation method, and p–t curves were measured in a closed bomb to investigate its practicality. The heat of combustion, sensitivity and hygroscopicity of the formula were measured according to China fireworks industry standard to verify the safety of the novel unpacking powder. The test results suggest that new unpacking powder using micronano porous silicon can effectively reduce the PM content and the product does not contain SO2, so it can be applied to export.

The effects of a variable-cavity liquid forging process on the microstructure and mechanical properties of an Mg-5Zn-1Y-0.6Zr magnesium alloy are described based on the results and analysis. The results indicate that the microstructure of the alloy changed clearly during the deformation process. After variable-cavity liquid forging, the dendrites are elongated along the deformation direction. The alloys with different deformation temperatures consist of α-Mg, the Mg-Zn phase, the I-phase (Mg3YZn6) and the W-phase (Mg3Y2Zn3). The I- and W-phases are mainly distributed in the grain boundaries, and the Mg-Zn phase is mainly dispersed in the grains. Most of second phase is broken into fine particles during the variable-cavity forging process. There is high dislocation density in the elongated grains at a deformation temperature of 350 °C, especially near the grain boundaries. Due to the dislocations, there are some tiny subgrain structures (less than 1 μm) formed near the second phase. After the variable-cavity liquid forging process, the subgrain structures did not recrystallize. The mechanical properties are significantly affected by the second phase and size of the grains. The highest tensile strength is 351.5 MPa at a deformation temperature of 350 °C, which is due to retained eutectic pockets. The best elongation is 7.15% at a deformation temperature of 450 °C, which is due to the tiny second phase particles and fine grains.

Background Limited data exist on VTE risk and prophylaxis in Chinese inpatients. The Identification of Chinese Hospitalized Patients' Risk Profile for Venous Thromboembolism-2 (DissolVE-2), a nationwide, multicenter, cross-sectional study, was therefore designed to investigate prevalence of VTE risks and evaluate VTE prophylaxis implementation compliant with the latest prophylaxis guidelines (American College of Chest Physicians [CHEST], 9th edition). Methods Adults admitted (≥ 72 h) to 60 urban, tertiary Chinese hospitals due to acute medical conditions or surgery from March to September 2016 were assessed for VTE risk. Risk assessments were made by using the Padua Prediction Scoring or Caprini Risk Assessment model, risk factors, and prophylaxis based on the CHEST guidelines, 9th edition. Results A total of 13,609 patients (6,986 surgical and 6,623 medical) were analyzed. VTE risk in surgical inpatients was categorized as low (13.9%; 95% CI, 13.1-14.7), moderate (32.7%; 95% CI, 31.6-33.8), and high (53.4%; 95% CI, 52.2-54.6); risk in medical patients was categorized as low (63.4%; 95% CI, 62.2-64.6) and high (36.6%; 95% CI, 35.4-37.8). Major risk factors in surgical and medical patients were major open surgery (52.6%) and acute infection (42.2%), respectively. Overall rate of any prophylaxis and appropriate prophylactic method was 14.3% (19.0% vs 9.3%) and 10.3% (11.8% vs 6.0%) in surgical and medical patients. Conclusions A large proportion of hospitalized patients reported VTE risk and low rate of CHEST-recommended prophylaxis. The data highlight the insufficient management of VTE risk and show the great potential for improving physicians' awareness and current practices across China. Trial Registry Chinese Clinical Trial Registry; No.: ChiCTR-OOC-16010187; URL: http://www.chictr.org.cn/showproj.aspx?proj=17077.

A ZK61-Y magnesium (Mg) alloy wheel hub was prepared via liquid forging&mdash, isothermal forging process. The effects of Y-element contents on the microstructure and mechanical properties of liquid forging blanks were investigated. The formation order of the second phase was I-phase (Mg3Zn6Y) &rarr, W-phase (Mg3Zn3Y2) &rarr, Z-phase (Mg12ZnY) with the increase of the Y-element content. Meanwhile, the I-phase and Z-phase formed in the liquid forging process were beneficial to the grain refinement. The numerical simulation of the isothermal forging process was carried out to analyze the effects of forming temperature on the temperature and stress field in the forming parts using the software Deform-3D. Isothermal forging experiments and post heat treatments were conducted. The influence of isothermal forging temperature, heat treatment temperature and preservation time on the microstructure and mechanical properties of the forming parts were also studied. The dynamic recrystallization (DRX), second-phase hardening, and work hardening account for the improvement of properties after the isothermal forging process. The forming part forged at 380 &deg, C displayed the outstanding properties. The elongation, yield strength, and ultimate tensile strength were 18.5%, 150 MPa and 315 MPa, respectively. The samples displayed an increased elongation and decreased strength after heat treatments. The 520 &deg, C&mdash, 1 h sample possessed the best mechanical properties, the elongation was 25.5%, the yield stress was 125 MPa and the ultimate tensile strength was 282 MPa. This can be ascribed to the recrystallization and the elimination of working hardening. Meanwhile, the second phase transformation (I-phase &rarr, W-phase &rarr, Mg2Y + MgZn2), dissolution, and decomposition can be observed, as well.

Thermal runaway and its propagation are bottlenecks for the safe operation of lithium-ion battery systems. This study investigates the influence of characteristic thermophysical parameters during battery thermal runaway, such as the self-heating temperature (T1), triggering temperature (T2), mass loss, and critical heat transfer power (Pc), on the failure propagation behavior in a battery system. A parametric study is conducted based on a failure propagation model. This model not only captures the behavior of thermal failure, but also accounts for the changes in the thermophysical parameters before and after thermal runaway. The results of the modeling analysis demonstrate that increasing T1 and T2 can both delay the thermal runaway propagation. The delay achieved by increasing T2 is greater than that observed by increasing T1. The peak heat transfer power Pc plays a critical role in delaying the thermal runaway propagation. When the peak heat transfer power level is greater than Pc, thermal runaway propagation mainly results from heat transfer, whereas when the peak heat transfer power level is less than Pc, thermal runaway propagation mainly arises from self-heating. This study reveals the dynamic mechanism of thermal runaway propagation within a battery module, thus providing guidance for the safety design of battery systems.

Gas generators are the functional materials producing gas by combustion. In situations such as pneumatics, fire extinguishing bomb, air bag, deep-water salvage, the gas generators can be ignited to provide power and energy through rapid release of gas. However, the research about gas generators with low water vapor is blank in world. The most widely used gas generators (such as nitroguanidine gas generators) produce a lot of water vapor through combustion, whose liquefaction will cause the reduction of gas pressure. This work selected 4,5-diazolyl-1,2,3-triazole (BTTZ) as gas-generating material. Two kinds of gas generator formulations based on BTTZ with common oxometallate (KNO3) and metal oxide (CuO) were designed. The properties of these gas generator formulations were studied by calculation and experiments. The gas production, gas production rate, water vapor content, compatibility and mechanical sensitivity were measured. The gas specific volume of the formulation 1 was 4.08 m3 kg−1. The clean harmless gas content reaches 93.55%. The water vapor content of the product was 6.08% (volume percentage), which is much lower than the nitroguanidine gas generators (53.47%). Therefore, formulation 1 is a low-water vapor environmental-friendly gas generator as a cleaner production material with practical value.

The problem of thermal runaway (TR) propagation challenges the safety design of battery packs, because it aggravates the thermal hazards to accidents. There are many unsolved scientific questions in understanding the mechanisms of TR and its propagation behavior for large format lithium-ion batteries (LIBs). LiNi

In this work, 7075 Al alloy, a high-strength wrought aluminum alloy with high hot tearing sensibility, was used in the squeeze casting of an asymmetric part. The solidification defects, microstructures and mechanical properties of the part solidified under different forming pressures were studied. Furthermore, the uniformities of the microstructures, mechanical properties and the solidification mechanisms were investigated. Results show that increasing the forming pressure is helpful to improve the liquid/solid feeding for counteracting the particularly serious shrinkage during the wide mushy zone of 7075 Al alloy. Therefore, the solidification defect can be avoided. Moreover, increasing the forming pressure is helpful to not only obtaining fine equiaxed grains, but also diminishing the intergranular segregation of alloying elements. With the increasement of forming pressures, the strengths of the part increased, along with the decreases in the ductile due to the work hardening resulted from the serious solid feeding. The microstructures and mechanical properties are impacted by the solidification rate of the melt at different regions. When the forming pressure was 150 MPa, fine microstructures and excellent mechanical properties were obtained. The uniformity of the microstructures and mechanical properties are dominated by the solidification location sequence of the melt. Further on, it is determined by the thermal gradient of the melt at different locations. For 7xxx series alloys, more solid feeding is needed for counteracting the serious shrinkage at the first solidified regions, causing a work hardening and associated strengths increasements. A near uniform part thickness and direct feeding loads are appreciated to improve the uniformities. In this work, the optimal tensile properties tested in the part were tested to be as follows: the yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) are 345.5 MPa, 483.2 MPa, and 7.6%, respectively. The UTS uniformity is tested to be 86.4%.

The development of electric vehicle batteries has resulted in high energy density battery pack. Cell-to-Pack (CTP) omits the cell module assembly, can reduce battery pack parts by 40%, improve the battery pack volume utilization rate by 15%–20%. However, the thermal characteristics of CTP under full operating conditions has yet to be verified, the CTP temperature calibration cycle under full working condition is time-consuming, and little analysis has been conducted on CTP internal temperature differentials and heat flow. The present study aims to thermal characteristics of CTP. Results show that CTP temperature calibration based on a thermal resistance grid can realize internal temperature reconstruction, optimum temperature arrangement, and shorten the calibration period by more than 60%. In addition, higher ambient temperatures can increase the maximum temperature of the jelly rolls in CTP cells, while lower ambient temperature can lead to larger differences in jelly roll temperature within a cell; and high-speed driving and fast charging can lead to the highest temperature increase rates under different working conditions up to 0.05 °C s−1.70% of the heat generated during cell discharge is used for self-heating, and the heat dissipation of liquid cooled plate is the main heat dissipation channel.

Cold is an important cause of the death of people who fall into the water. The use of a gas generating agent to inflate an inflatable lifejacket is a kind of self-heating inflatable lifejacket, which maintains the inflation effect and portability of the original lifejacket and can also play an auxiliary heating effect. In this paper, a nitrogen-rich substance, 5-aminotetrazole 3-nitro-1,2,4-triazole (5ATNTZ) was synthesized, together with the selected oxidant and binder to complete the preparation of the gas generating agent. Commercial life jackets were selected for inflation test to explore the actual dosage and inflation effect of gas generating agent. The experimental results show that when the amount of gas generating agent is 19 g, the amount of physical coolant is 20 g, and the amount of chemical coolant is 7 g, the lifejacket is inflated and its surface temperature reaches at least 40.3 °C. The energy utilization efficiency reaches 75.17% when the chemical energy of the gas generating agent is converted into the heat of the bag and inflation work in the whole inflation process. Therefore, the gas-filled lifejacket using a gas generating agent has a good auxiliary heat effect, and is a type of self-heating inflatable lifejacket with excellent performance, which has great application value.

Black powder is often used as propellant in the fireworks industry, but the sulphur in the black powder will pose great risks to the environment and human health. Although there are sulphur-free propellant with metal powder and smokeless propellant prepared from expired military gunpowder to solve the problem, the high sensitivity and huge explosive power of the mental powder and instability of the expired military gunpowder lead to low security in actual application. Therefore, sulphur-free propellant which can replace black powder is urgently needed. In this study, a discharge height test was conducted for the sulphur-free environmental protection formulation [potassium perchlorate (70%), potassium hydrogen terephthalate (10%), carbon (11%), ferrocene (1%), phenolic resin (7%), calcium stearate (2%)] optimized by an orthogonal test. The thermal explosion in critical temperature was used to determine the thermal stability of sulphur-free propellant and black powder, then compared with combustion heat. The preesure-time test was used to compare the peak pressure of this two propellant. The impact, friction and flame sensitivity were also measured. It is thought that sulphur-free propellant can replace the black powder as the new environmental-friendly propellant in the fireworks industry with low sensitivity and excellent storage performance, and have great potential in application.

This work sets focus on producing hydrophobic silica and fire-extinguishing-composition solution into dry water extinguishant powder by high-speed shearing. The solid-to-liquid ratio, different stirring periods and rotational speed were taken into account to analyze their influence on the covering effect. The dry water extinguishants containing ammonium dihydrogen phosphate (ADP) and phosphoric acid are respectively produced added with gel. The jet apparatus is improved for the experiment. According to the results, the phosphoric acid gel dry water extinguishant works best to put out Type-A fire. The ADP dry water extinguishant excels in putting out Type-B fire, equivalent to superfine ABC dry powder extinguishant in terms of effectiveness but with a low cost. For this reason, dry water extinguishant has a broad prospect of application.

Mg-Zn-Zr-Y billets with different mass fraction of Y (wt%(Y)=0.2%、0.5%、1.0%、1.5%、2.0%) was prepared by permanent mold casting. The increase in Y content has shown grain refinement effects on the microstructure morphologies of Mg–Zn–Y–Zr alloys. When the content of Y achieves 1.0 wt%, the grain refinement effect of the Y is most obvious than any more contents of the Y content. In the test result of XRD, the type of precipitated phase in Mg-Zn-Zr-Y alloys is related to atomic ratio of Y/Zn. With content of Y increases, atomic ratio of Y/Zn increases,the precipitated phase in alloy is changed from Phase I to Phase W. Tensile strength and extension rate of alloy increase with the increasing of Y content; When Y content reaches 1.0%, mechanical property reaches maximum value.When content of Y exceeds 1.0%, with the increasing of Y content, mechanical property of alloy declines gradually.

The normal pyrotechnically generated aerosol extinguishing agent is effective in extinguishing Class B fire, but have difficulty extinguishing the Class A wood-crib fire. To solve this problem, an experiment has been made in this paper to study the extinction effectiveness of a new type of pyrotechnically generated aerosol extinguishing agent in wood crib fire. Differing from the old ones, the new type of pyrotechnically generated aerosol extinguishing agent generates via combustion of aerosol forming agents containing a kind of phosphorus-containing compound named P90x, which is flammable and has been widely used as fire retardants in materials. P90x was added, for the first time, as a reducer into aerosol forming agents to improve the capabilities against the Class A wood-crib fire. Five aerosol forming agents with the different mass ratio of P90x and potassium nitrate were tested for fire extinguishing efficiency. The fire extinguishing efficiency increased as the amount of P90x increases. And the best fire extinguishing efficiency in this experiment was 20 g/m 3 for wood-crib fire. This new type of aerosol extinguishing agents can adhere to the surface of burning wood and react with it to extinguish fire efficiently. Therefore, the Class A fire (wood cribs) can be extinguished by pyrotechnically generated aerosol extinguishing agents for the first time from all over the world.

Up to now, the research studies about 5-aminotetrazole (5-AT) gas generators are still not complete. In this work, ten gas generators based on 5-AT with different ordinary oxidants were designed. A...

Background Proteinuria is common in patients with acute heart failure (AHF). This study investigated the relationship between proteinuria and short-term mortality among patients hospitalized for AHF at two university hospitals. Methods Adult hospitalized patients with AHF were retrospectively studied. Proteinuria was defined based on the first urine dipstick test within 48 h after the AHF diagnosis. The death risk was assessed using an Enhanced Feedback for Effective Cardiac Treatment (EFFECT) 30-day mortality risk score. Results Of the 1,058 eligible patients with AHF, 583 (55.1%) exhibited proteinuria. The degree of proteinuria was positively correlated with poor AHF prognostic indicators (C-reactive protein and N-terminal pro-brain natriuretic peptide) and negatively correlated with protective indicators (basal estimated glomerular filtration rate, haemoglobin, and serum albumin). The EFFECT mortality risk score and the in-hospital mortality rate of patients with proteinuria were significantly higher than that of the patients without proteinuria. According to different multivariate logistic regression models, proteinuria increased the risk of in-hospital mortality after correcting for multiple variables, including the EFFECT mortality risk score, diabetes, RASI, NT-proBNP, albumin and chronic kidney disease stages. Compared with the NT-proBNP, proteinuria and degree of proteinuria yielded higher areas under the ROC curve for predicting in-hospital mortality. Conclusions Our results demonstrate that proteinuria correlates with the short-term mortality rate of patients hospitalized for AHF. Dipstick proteinuria testing might represent a promising prognostic indicator for these patients.

A human torso finite element model with high bio-fidelity was developed to study the behind armor blunt trauma (BABT) of pistol cartridge on human torso with bulletproof composite structure (BCS) and the effect of buffer layer (expandable polyethylene, EPE) on BABT. The bulletproof structure was made of multilayered composite of aluminum alloy (AlSi10Mg) and thermoplastic polyurethanes (TPU), and the ANSYS/LS-DYNA software was used to simulate the blunt ballistic impact process of pistol cartridge on human torso. Results indicated that the BCS could resist the shooting speed of 515 m/s without being broken. During the process of pistol cartridge shooting the BCS, the energy of pistol cartridge was transmitted to the human organs through the BCS, thereby causing human injury. Moreover, the mechanical response parameters of various organs were determined by the distance between the human organs and the impact point. The sternal fracture and liver rupture were not produced based on the threshold stress of sternum and liver injury, no matter whether the buffer layer was added or not. According to the Axelsson injury model, a slight to moderate injury was created when there was no buffer layer, but the injury level was trace to slight caused by the buffer layer with thickness of 1.0 mm, and the buffer layer with thickness of 2.5 mm and 5.0 mm caused subtle BABT. It was concluded that the buffer layer could effectively reduce the BABT, and the reduction was related to the thickness of the buffer layer. This study reveals the mechanism of the BABT, which can provide a theoretical basis for the design of the bulletproof structure and the evaluation of structural bulletproof performance and protection performance.

At present, the inflatable expansion of a flexible compartment of a spacecraft mainly depends on the compressed gas cylinder. However, there are some problems in the technology of compressed gas cylinders, such as large volume, heavy mass and non-environmental protection. In view of the above problems, a new space inflatable deployment system is innovatively proposed in this work. The system mainly includes a gas generating agent formulation with safety, stability, low combustion temperature, slow gas production, environment-friendly and clean, and a gas generator with simple structure, light weight, small volume and a flexible compartment. The gas released from the system is charged into the flexible compartment of the spacecraft smoothly. Then, the spacecraft flexible compartment is used to carry out experiment and the resulting gas was subjected to test. The results show that the main gas produced by the system is clean and nontoxic nitrogen. In addition, the whole expansion process is stable, slow and smooth. It can be seen that the space inflatable deployment system will have a good application in the field of spacecraft.

The Nalinggou–Daying uranium metallogenic belt is situated at the northern Ordos Basin, China. Petrographical, mineralogical and geochemical techniques were used to study the ore-bearing sandstones and host rocks in the Nalinggou–Daying uranium metallogenic belt. The present study shows that uranium minerals, i.e., coffinite, pitchblende, and brannerite, are mostly disseminated around pyrite and detrital particles. The ore-bearing sandstones are enriched in organic matter, with which this reductive environment influenced uranium leaching. The carbonate concentration of the uranium ores is markedly higher than that of the host rocks, and intense carbonatization occurs in the ore-bearing sandstones. In this case, the usage of the classical in-situ leach uranium mining technique by injecting H2SO4 + H2O2 solution produces calcium sulfate precipitate, which can lead to blocking of the ore-bearing strata. For this reason, laboratory and field uranium mining tests were conducted using CO2 + O2 in-situ leaching technology and were demonstrated to be successful, illustrating that this approach is technically feasible. Inhibiting ore bed blockage and increasing the amount of injected O2 are important for uranium leaching in this setting.

Six types of gas generators based on guanidinium azotetrazolate (GZT) were designed into six formulations having different oxidants: GZT-LiNO3 (1), GZT-NaNO3 (2), GZT-KNO3 (3), GZT-Mg(NO3)2 (4), GZT-Sr(NO3)2 (5) and GZT-KMnO4 (6), respectively. The properties of these formulations were investigated in terms from gas production, appropriate combustion temperature and nontoxic gaseous emission. REAL software calculation program [1] was used to calculate the combustion heat at constant pressure, combustion heat at constant volume and specific volume in standard state. It showed that gas generators based on GZT with nitrate salts as oxidant exhibited better performance. Thus its thermal behavior and combustion temperature were studied further and the experimental results were consistent with the theoretical calculation results. Therefore, it can be concluded that formulation 3 has comprehensive optimal performance: low moisture content, insensitivity to friction, heightened vacuum stability, high combustion heat and specific volume. Namely, formulation 3 exhibited the most promising indications of commercial application, such as using in air bags of motor vehicles.

A cup burner was used to measure the minimum fire extinguishing concentrations for methane extinguishment by fine water mist with additives/air co-flow diffusion flames based on ultrasonic atomization. The comparison of the minimum fire extinguishing concentrations of pure and fine water mist revealed that the existence of additives could change the fire extinguishing efficiency of pure water, with their improvement effect ranked as KCl > KH 2 PO 4 > NH 4 H 2 PO 4 . A flame thermal balance equation was established, and a model for predicting the minimum fire extinguishing concentrations of different fire extinguishing agents was developed. A differential scanning calorimeter was used to measure solution heat capacity, and the physicochemical properties of different liquid extinguishers were predicted. When the mass fractions of the additives equated to 2%, the chemical fire extinguishing effect was superior. The influence of additives on fire extinguishing efficiency mainly involves an increase in chemical actions and a reduction in the competition between the evaporative capacities of pure water.

This study analyzed the effects of both water mist and water mist with different additives on cooling of cooking oils during fire extinguishment. The sizes of water mist drops with different additives were measured using a split-type laser particle analyzer. Full-scale extinguishment–cooling experiments using different fire extinguishing agents and oil temperatures were also conducted. The boiling over layer formed during the cooling of cooking oil using water mist could significantly enhance the cooling rate. Moreover, the expanding rate of this boiling over layer is related to oil temperature and water mass in oils. Although additives reduce water evaporation and hinder oil cooling, such additives also inhibit the expansion of the boiling over layer, thereby reducing the risk of secondary damage caused by abundant oil overflow after the fire extinguishment.

In order to study the thermal safety of cylindrical battery deeply, based on the theory of heat transfer, thermal explosion and nonlinear modeling, a three-dimensional non-steady state thermal explosion mathematical model of cylindrical fireworks with non-uniform heat dissipation of the lateral surface was established for the first time (three-dimensional partial differential equation group). Combining seven point difference method and Newton-homotopy algorithm, the numerical calculation method of the three-dimensional non-steady state thermal explosion partial differential equation was established and the numerical calculation program was written base on Matlab. The validity of calculation program has been demonstrated by comparison of numerical solutions and classical solutions. The accuracy of model has been validated by example computation and analysis. The critical parameters describing non-steady state model of cylindrical fireworks when stored individually and stored in combination form were calculated in this paper, including temperature distribution, temperature–time history, thermal explosion time to ignition, etc. The results show that when the ambient temperature is 450 K, the fireworks stored individually do not have thermal explosion, but the fireworks stored in combination form will explode finally and the thermal explosion time to ignition is 19013.53 s. When the ambient temperature is 460 K, thermal explosion will occur in both the fireworks stored individually and stored in combination form, and the thermal explosion time to ignition are 3187.07 s and 3066.60 s respectively. It shows a more exact analytical methods and solutions of thermal safety evaluation of fireworks was established in this paper. Thus, it is need to strengthen the safety monitoring and management of cylindrical battery (combined fireworks) because of the higher thermal hazard.

Cooking oil fires which happened in the kitchen or hotel have become quite popular over the last decades. Compare to other types of fires, cooking oil fires are very difficult to extinguish. Both foam and powder can effectively extinguish the flames over the oil surface but they are very difficult to cool the oil below its auto-ignition temperature and to prevent it from re-ignition due to their limited cooling capacity. Moreover, water mist with additives may be applied to provide additional improvements in terms of suppression effectiveness and temperature control of cooking oil fires. The present work establishes a series of home-scale experiments to study extinguishing mechanisms and effectiveness of pure water and water mist with additives against cooking oil fires. The thermal transient within the test chamber has been evaluated during the fire development as the main quantitative parameter. Results showed that water mist is shown to be efficient in cooking oil fires control, especially endowed with the chosen additives which demonstrated that water mist with additives would extinguish cooking oil fires through physical and chemical mechanisms. Furthermore, the change in fire extinguishing efficiency differs for different additives and mass fractions of the additives.

Solid–liquid segregation often occurred during thixoforming of wrought aluminum alloys, which can result in uneven structures and mechanical properties. In this work, a novel compound loading method was introduced in thixoforming 7075 aluminum alloys. The results show that the solid–liquid segregation can be alleviated evidently by compound loading, and the microstructures of periphery area were improved significantly. As the secondary loading displacement increased from 0 mm to 5 mm, the ultimate tensile strength (UTS) of the periphery area increased little (∼510 MPa), and the yield strength (YS) even decreased slightly from 486 MPa to 470 MPa. However, the elongation to fracture of the periphery area increased from 1.94% to 4.3% with increment of 122%. On the contrary, the compound loading has limited effect on the tensile mechanical properties of the center area. The tensile fracture surfaces exhibited typical brittle rupture in the periphery area, while the fracture surfaces of the center were dominated by a large number of dimples and tear ridges showing typical ductile fracture features. Compound loading is an effective method to homogenize the microstructures and mechanical properties of thixoformed wrought aluminum alloys.

To study the effect of variable heat transfer coefficient of fireworks and crackers on thermal explosion critical ambient temperature and time to ignition, considering the heat transfer coefficient as the power function of temperature, mathematical thermal explosion steady state and unsteady-state model of finite cylindrical fireworks and crackers with complex shell structures are established based on two-dimensional steady state thermal explosion theory. The influence of variable heat transfer coefficient on thermal explosion critical ambient temperature and time to ignition are analyzed. When heat transfer coefficient is changing with temperature and in the condition of natural convection heat transfer, critical ambient temperature lessen, thermal explosion time to ignition shorten. If ambient temperature is close to critical ambient temperature, the influence of variable heat transfer coefficient on time to ignition become large. For firework with inner barrel in example analysis, the critical ambient temperature of propellant is 463.88 K and the time to ignition is 4054.9s at 466 K, 0.26 K and 450.8s less than without considering the change of heat transfer coefficient respectively. The calculation results show that the influence of variable heat transfer coefficient on thermal explosion time to ignition is greater in this example. Therefore, the effect of variable heat transfer coefficient should be considered into thermal safety evaluation of fireworks to reduce potential safety hazard.

1,5-diaminotetrazolium chloride (DATC) and 1,5-diaminotetrazolium sulfate (DATS) were synthesized in this work. The structures of DATS and DATC were characterized. The single crystal of DATS was first cultured, and its structure was analyzed. The thermal behavior of DATS was investigated. The activation energy and pro-exponential factor were calculated, Ek = 120.86 KJ/mol, Ak = 1012.96 s−1. The density, heat of formation, detonation pressure, and detonation velocity of DATS were first calculated. The detonation pressure and detonation velocity of DATS are P = 11.877 GPa, D = 5.617 km s−1, which are smaller than those of 1,5-diaminotetrazolium nitrate (DATN) (P = 33.3GPa, D = 8.77 km s−1).

The formation process of Al3Ti was studied based on the in-situ reaction between globular solid Ti powders with almost uniform size and 2024 Al melt under ultrasonic vibration. The microstructures of the Al3Ti/Al composite were examined at different reaction time. The reaction mechanism was analyzed based on the phase diagram and empirical reaction kinetics. Moreover, the effects of ultrasonic vibration on the formation of Al3Ti were discussed. The results show that the Al3Ti formed a layer around the unreacted Ti particle and was ruptured as the reaction continuing. An empirical reaction kinetics model of in-situ Al3Ti was established. The kinetic exponent n is determined to be 0.86, which is much higher than that of the standard diffusion-controlled growth (n = 0.5). The ultrasound assisted reaction follows an interface-controlled growth which means a higher reaction rate. The comprehensive effects of instantaneous pressure, high-intensity shock waves and local high-temperature caused by acoustic streaming and cavitation, are responsible for the high reaction rate and fine Al3Ti particles during the reaction process under ultrasonic vibration.

To study the injury of blast wave on the human torso, a human torso finite element model (HTFEM) consisted of multiple organs with high fidelity was developed. Based on LS-DYNA finite element software, the LBE-ALE method was used to simulate the mechanical response process of human torso under blast loading. The effect of blast loading on the mechanical response of human organs was analyzed, which indicated that as the blast loading increased, the greater the stress and velocity of human organs, and when the mass of TNT charge was constant, the earlier the onset time and peak time of stress and velocity response, the faster the stress and velocity changed; meanwhile the gap in stress and velocity of same human organ widened under different masses of TNT charge, the gap in stress and velocity between different human organs widened under the same mass of TNT charge, but the gap between different human organs narrowed under the same scaled distance. Besides, the location of human organs and the action direction of blast loading had a significant effect on the mechanical response. The stress threshold of human organs was proposed, which ranged between 218.42 kPa and 153.65 MPa corresponding to 50% lethality.

The synthesis mechanism of 3-nitro-4-(tetrazol-5-yl)furazan (NTZF) was calculated by Gaussian 09 for the first time, and NTZF was successfully synthesized based on the theoretical design. Its ionic salts (RbNTZF and CsNTZF) were synthesized and studied by single-crystal X-ray diffraction firstly. The thermal stability of NTZF was investigated by TG-DSC and the kinetic data of thermal decomposition were calculated. The sensitivity of NTZF was measured. The formation heat, detonation velocity (D) and detonation pressure (P) of NTZF were calculated. NTZF is insensitive to impact and friction (impact > 40 J, friction > 360 J) and has higher detonation velocity and pressure (D = 7.838 km s−1, P = 27.32 GPa) compared to TNT (D = 6881 m s−1, P = 19.5 GPa). NTZF has appropriate sensitivity and detonation performance, so it can be used as a low explosive and gas generant.

2-Methyl-4,5-dicyano-2H-1,2,3-triazole was synthesized with 4,5-dicyano-2H-1,2,3-triazole as the raw material for the first time. Its structure was characterized by elemental analysis, infrared spectrum, and nuclear magnetic resonance spectrum. The thermal stability of 2-methyl-4,5-dicyano-2H-1,2,3-triazole was investigated by TG–DSC technique. Its kinetic parameters including activation energy and pre-exponential factor were calculated by Kissinger equation. The combustion heat, heat of formation, impact and friction sensitivity of 2-methyl-4,5-dicyano-2H-1,2,3-triazole were measured. Also, 2-methyl-4-acylamino-5-cyano-2H-1, 2,3-triazole was formed by the hydrolysis of one of the cyano groups of the 2-methyl-4,5-dicyano-2H-1,2,3-triazole, and its single crystal was cultivated. The molecular structure of 2-methyl-4-acylamino-5-cyano-2H-1,2,3-triazole was determined using X-ray diffraction [triclinic P-1, a = 4.956(2) A, b = 10.058(5) A, c = 14.142(7) A, β = 91.169(4)°, V = 658.7(6) A3, Z = 4]. It exhibited potential application prospect in gas generant, explosive, and solid propellant field.

4,5-Bis(5-tetrazolyl)-1,2,3-triazole (BTT) was synthesized by a new method. Its structure was characterized by IR and 13C NMR spectroscopy and elemental analysis (EA). The thermal stability of BTT was investigated by TG-DSC technique. The kinetic parameters including activation energy and pro-exponential factor were calculated by Kissinger equation. The combustion heat, detonation products, hygroscopicity, impact, and friction sensitivity were also measured. The formation heat, detonation pressure, and detonation velocity of BTT were calculated. BTT has high detonation pressure and detonation velocity (P=35.36 GPa, D=8.971 km s−1). BTT has potential application prospect as environmentally friendly gas generant, insensitive explosive and solid propellant.

Bis (1, 5-diamino-4-methyl-tetrazolium) azotetrazolate (BMDATZT) was synthesized with high yield in this work. The yield is 97.46%. The structure was characterized by IR, 1H NMR, and MS. The single crystal of BMDATZT•2H2O was first cultivated. The heat of formation, detonation pressure, and detonation velocity were first calculated. The crystalline density of BMDATZT•2H2O is 1.573 g/cm3. BMDATZT has high detonation pressure and detonation velocity (P =25.06 GPa, D = 7.805 km s−1), which are higher than those of 2,4,6-Trinitrotoluene (TNT). Its thermal and mechanical sensitivities are moderate. Therefore, it is a kind of insensitive nitrogen-rich energetic ionic salt with good performance, and it has potential application prospect in gas generating agent, explosive and solid propellant.

Al-Zn-Mg-Cu alloys are the strongest aluminum alloys which have been widely used for aerospace applications. They are usually machined from the wrought state usually with a high waste percentage. To reduce waste, it is important to thixoform these alloys in near net shape. In this work, the thixoformability of a commercial high performance Al-Zn-Mg-Cu alloy 7075 was studied. A novel multistep reheating regime was developed in recrystallization and partial melting (RAP) route to obtain spheroidal semi-solid microstructures. The as-extruded 7075 alloy was fully recrystallized for a short holding time using the multistep reheating regime. Semi-solid microstructures with fine and spherical solid grains with a grain size of 40-50 μm embedded in liquid matrix were obtained. The advantage of the multistep reheating regimes over those conventional routes was also discussed. Some wheel-shaped components were thixoformed from the as-received 7075 alloy. The ultimate tensile strength, yield strength and elongation to fracture of the thixoformed component based on multistep reheating regime, are 510 MPa, 446 MPa and 17.5% respectively. These values are superior to those of the products manufactured with the conventional RAP route. As the results indicated, thixoforming could be conducted based on commercial extruded Al-Zn-Mg-Cu alloys, which has important practical significance.

The synthesis and characterization of the 4,5-dicyano-2H-1,2,3-triazole anion in its 5-aminotetrazole, 1,5-diaminotetrazole, and 1,5-diamino-4-methyl-tetrazole salts are reported. All compounds were characterized by IR, 1H NMR, and 13C NMR spectroscopy, as well as elemental analyses. Their thermal decompositions were investigated by TG-DSC. The densities, combustion heats, and sensitivity properties were tested. Additionally, enthalpies of formation, detonation pressures, detonation velocities, and heats of detonation were calculated. The compounds have potential application in the energetic materials field.

Taking carbon series conductive coatings as the research object, research on a modificatory filler was carried out to achieve higher electrical conductivity. Under the condition of this paper, the conductivity of the modified carbon black was improved, while the performance of the modified graphite was not obviously improved. The conductivity and dispersion of the modified carbon fibre were both improved. Analysing the impact of the additive on the performance of conductive coatings in which carbon black accounted for 10%, the conductivity was best when the weight of the tetra-butyl titanate was 1% of the filler. Adding an anti-settlement agent also improved the performance of the conductive coatings, and the best consumption was about 0.6% of the weight of the filler.

The nitrogen content of tetrazolo[l,5-b][1,2,4]triazine is 68.9%. It has a good application prospect in energetic material field. The synthesis was carried out, and the single crystal was cultivated. The analysis showed that the two rings of tetrazolo[l,5-b][1,2,4]triazine are in the same flat, and the molecular accumulation displayed the net-like structure in the space. The thermal decomposition process was studied. The relationship between weight loss and temperature, and the thermal decomposition temperature were gained from thermogravimetry-differential thermogravimetry and differential scanning calorimetry. These provide the reference for its application in energetic material.