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BackgroundWith the continuous development of society and economy, nuclear energy has emerged as a crucial solution to address global energy shortages. However, uranium reserves on land have diminished after nearly half a century of extraction, resulting in irreversible harm to the natural environment. Consequently, seawater uranium extraction has become a more eco-friendly and abundant source of uranium resources, compared to terrestrial uranium mining. And extracting uranium from seawater emerges as a prudent strategy.PurposeThis study aims to use kinetic chromatography to extract uranium from seawater and investigate the separation mechanism.MethodsLeveraging the concepts of dynamic chromatography, a pulsed-injection energy-endowed kinetic chromatography column was developed. The column utilized spherical SiO2 with a diameter of 0.2 mm and a length of 5 m as the filler. After filling, it encompassed approximately 30 600 chromatographic separation units. A peristaltic pump for pulse injection was applied to the kinetic chromatography system, and a switching pulse injection device was equipped to enable time control splitting. Subsequently, a self-developed on-line spectrophotometric detector was utilized to monitor the concentration of target components in the solution in real-time so as to avoid human control errors during multistage separation experiments. Additionally, the behavior of uranyl ions in kinetic chromatography under varying conditions and determine the best separation conditions was investigated by experiments using different mobile phase carriers, pH values, injection flow rates, energy-endowed modes, and energy-endowed series, and various energy-endowed methods, including water bath heating, ultrasonic, and external magnetic fields, were employed to achieve optimal separation conditions. Finally, the separation factor of uranium and sodium ions in actual seawater uranium extraction was calculated to explore the separation mechanism by separate studies of uranium, europium, and sodium ions, as well as an actual seawater uranium extraction.ResultResults of this series of studies demonstrates that the best separation effect is achieved when using hydrochloric acid as the mobile phase carrier in dynamic chromatography, with a pH of 2, a sample flow rate of 4.109 mL·min-1, water bath heating as the energy-endowed mode, a heating temperature of 50 ℃, and a heating series of 4. Under these optimal conditions, the separation factor between uranium and sodium ions can reach 1.185 4 in the separation studies of uranium, europium and sodium ions. In the real seawater uranium extraction study, the separation factor between uranium and sodium ions can reach 1.575. After simulation and calculation, the theoretical separation of uranium and sodium ions in seawater requires a minimum of 20 levels.ConclusionsThe efficient and rapid extraction and separation of uranium from seawater is facilitated in this study using a pulsed-injection energy-endowed kinetic chromatography column. This separation strategy allows for the efficient separation of light and heavy particles without interaction of the mobile and stationary, resulting in a high sample recovery rate and no need for column regeneration. This technique has potential for the separation of other nuclides, making it a versatile tool for nuclear chemistry research.

Xiaofeng Sun,1 Junhong Cai,1 Hongkui Yu,1 Ting Zhang,1 Lanlang Zhang2 1Department of Ultrasound, Shenzhen Baoan Women’s and Children’s Hospital, Shenzhen, Guangdong Province, 518102, People’s Republic of China; 2Department of Hemodialysis, Fuyong People’s Hospital of Baoan District, Shenzhen, Guangdong Province, 518103, People’s Republic of ChinaCorrespondence: Lanlang Zhang, Department of Hemodialysis, Fuyong People’s Hospital of Baoan District, Shenzhen, Guangdong Province, 518103, People’s Republic of China, Tel +86-13603098960, Email 710394655@qq.comBackground: Transvaginal four-dimensional hysterosalpingo-contrast sonography (TVS 4D-HyCoSy) is a pivotal diagnostic tool in the assessment and management of infertility. Conventionally, a 20mL syringe is employed for contrast agent injection, either at a constant or pulsatile pressure. However, in cases of bilateral fallopian tube obstruction, continued injection can lead to discomfort and excessive pressure within the uterine cavity, necessitating discontinuation of the examination.Case Presentation: In this illuminating case study, a patient underwent TVS 4D-HyCoSy due to infertility concerns. Initial contrast agent injection failed to visualize both fallopian tubes, accompanied by acute pain. Bilateral tubal obstruction was diagnosed, prompting an innovative approach. A 2.5mL syringe was chosen for pulsed injection, leading to successful visualization of patency in one fallopian tube. Remarkably, the patient achieved natural pregnancy within three months of the examination.Conclusion: Pulsed injection using a small-volume syringe emerges as a promising technique in cases of fallopian tube obstruction during TVS 4D-HyCoSy. This method not only enhances patient comfort but also improves the likelihood of visualizing fallopian tube patency, contributing to accurate infertility assessments. As a supplementary technique, it addresses limitations associated with constant pressure injection and offers a novel approach to enhance diagnostic success.Keywords: hysterosalpingography, tubal obstruction, contrast agent, pulsed injection, small-volume syringe

Scramjet refers to air entering the combustion chamber at supersonic speed and then mixing and burning with fuel. However, in the condition of such a fast flow speed, it is difficult to achieve full mixing and stable combustion of fuel and air. The previous condition of stable combustion is the full mixing of fuel and air. Therefore, the study of mixing enhancement plays an important role in the development of scramjet engines. Many scholars at home and abroad continue to study and propose mixing enhancement methods to solve the problem of full mixing of fuel and air. This paper mainly summarizes the research progress of transverse injection, pulsed injection and cavity in the mixing enhancement approaches, and puts forward prospects for future development.

The effect of the curvature of the blade and the existence of pulsation in compressor injection air highlights the importance of pulsating flow analysis on a complete turbine blade. Sinusoidal and square pulsed film cooling on leading-edge (LE), pressure and suction sides (PS and SS) of a complete NASA C3X blade is numerically investigated. The performance of film cooling is studied for five blowing ratios from 0.5 to 2.5 at the frequency of 50 Hz and three of the mainstream Reynolds numbers (Re). The numerical simulations have been performed by the S S T k - ω model. The results showed that film effectiveness is different for the two considered pulse flows. The most value of averaged film effectiveness is obtained on PS, in which its minimum happens at the LE. For the sinusoidal pulse, the average film effectiveness was almost two times more than the square wave. With increasing the blowing ratio, pulsed film cooling effectiveness is reduced at LE and PS but at SS this trend was reversed. The averaged centerline pulsed film effectiveness on the LE and PS at the blowing ratio of 0.5 and for SS at the blowing ratio of 2.5 was maximum. The effect of mainstream Reynolds number variations on pulsed film cooling had the most effect on PS. At LE and SS, at R e = 74652 , film effectiveness was the most value while at PS for R e = 111978 the largest effectiveness was obtained. [ABSTRACT FROM AUTHOR]

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The relationship between the purge time and the overall growth rate in pulsed injection metal–organic chemical vapor deposition with different V/III ratios is studied by numerical analysis. The transport behavior of TMAl and TMAlNH3 during the process is studied to understand the effect of the adductive reaction. The results show that, as the V/III ratio increases, there is a significant reduction in the average growth rate per cycle, without the addition of a purging H2 pulse between the III and V pulses, due to stronger adductive reaction. The adductive reaction can be reduced by inserting a purging pulse of pure H2 between the III and V pulses, but there is a decrease in the overall growth rate due to the longer cycle time. At smaller V/III ratios, the growth rate decreases with increasing purge times, since the gain in reducing the adductive reaction is offset by the detrimental effect of extending the cycle time. The degree of reduction in the adductive reaction is higher for larger V/III ratios. When the benefit of reducing the adductive reaction overcomes the deficiency of the extending cycle time, a remarkable enhancement of the growth rate can be obtained at high V/III ratios by inserting a pure H2 purge pulse between the III and V pulses. A higher overall growth rate can be achieved at higher V/III ratios by choosing an appropriate purge time. [ABSTRACT FROM AUTHOR]

This paper describes the pulsed injection of hydrogen fuel with an incoming Mach number of 2.5 in a directly connected pulse combustion wind tunnel. The hydrogen pulse injection test with 33 Hz–62hz frequencies was carried out by using a mechanical pulse injector.The effects of different injection frequencies on the ignition delay and combustion performance of the hydrogen fuel are analyzed by means of flame self-luminescence photography and wall pressure measurements, and the results are compared with those of steady injection. The results shows that there is an optimal pulsed injection frequency--39 Hz in the frequency range studied in this paper, at this frequency, the ignition delay of hydrogen is much shorter than that of steady injection.In addition, the study also found that pulsed injection improves the combustion performance of hydrogen, so that the energy released by hydrogen combustion at lower equivalence ratios is equal to that released by steady hydrogen injection at a higher equivalence ratio. For both pulsed and steady injection, the development of the hydrogen flame can be attributed to the propagation theory of diffusion flame. The pulse frequency is not observed to have any significant effects on hydrogen combustion performance. • Effects of steady injection and pulsed injection on ignition and combustion were studied. • The results show that 39 Hz pulsed injection can greatly shorten hydrogen ignition delay. • Penetration depth of pulsed injection is higher than that of steady injection. • Pulsed injection can improve the combustion performance of hydrogen. [ABSTRACT FROM AUTHOR]

The relationship between the purge time and the overall growth rate in pulsed injection metal–organic chemical vapor deposition with different V/III ratios is studied by numerical analysis. The transport behavior of TMAl and TMAlNH3 during the process is studied to understand the effect of the adductive reaction. The results show that, as the V/III ratio increases, there is a significant reduction in the average growth rate per cycle, without the addition of a purging H2 pulse between the III and V pulses, due to stronger adductive reaction. The adductive reaction can be reduced by inserting a purging pulse of pure H2 between the III and V pulses, but there is a decrease in the overall growth rate due to the longer cycle time. At smaller V/III ratios, the growth rate decreases with increasing purge times, since the gain in reducing the adductive reaction is offset by the detrimental effect of extending the cycle time. The degree of reduction in the adductive reaction is higher for larger V/III ratios. When the benefit of reducing the adductive reaction overcomes the deficiency of the extending cycle time, a remarkable enhancement of the growth rate can be obtained at high V/III ratios by inserting a pure H2 purge pulse between the III and V pulses. A higher overall growth rate can be achieved at higher V/III ratios by choosing an appropriate purge time.

A novel injector has been designed and cold flow injection tests were performed in a modified supersonic wind tunnel. To complement these experimental studies three dimensional STAR-CCM+CFD simulations were developed. The pulse width may be varied, with options of injecting gas for 33 %, 50 % and 66 % of the injection period. The scramjet combustor environment is simulated in a supersonic wind tunnel through a backward facing step for secondary injection purposes and a 157.5 cm (62-inch) long test section. The gas in secondary injection is carbon dioxide and the primary flow is air. The simulations show a coupled interaction between the forcing from injection and the shear layer. Steady state static pressure measurements on the lower wall of the wind tunnel test section agree well with the simulated static pressure along the lower wall. The pulse width strongly impacts shear layer reattachment on the lower wall and varies between 2.4 and 4.3 step heights. Reduction in duty cycle from 66 % to 33 % at 1 kHz caused ~30 % reduction in the shear layer reattachments distance, which points to large scale mixing enhancement. [ABSTRACT FROM AUTHOR]

Achieving efficient fuel-air mixing is a crucial issue in the design of the scramjet engine due to the compressibility effect on the mixing shear layer growth and the stringent flow residence time limitation induced by the high-speed crossflow, and the potential solution is to enhance mixing between air and fuel by introducing of streamwise vortices in the flow field. In this survey, some mixing enhancement strategies based on the traditional transverse injection technique proposed in recent years, as well as their mixing augmentation mechanisms, were reviewed in detail, namely the pulsed transverse injection scheme, the traditional transverse injection coupled with the vortex generator, and the dual transverse injection system with a front porthole and a rear air porthole arranged in tandem. The streamwise vortices, through the large-scale stirring motion that they introduce, are responsible for the extraction of large amounts of energy from the mean flow that can be converted into turbulence, ultimately leading to increased mixing effectiveness. The streamwise vortices may be obtained by taking advantage of the shear layer between a jet and the cross stream or by employing intrusive physical devices. Finally, a promising mixing enhancement strategy in supersonic flows was proposed, and some remarks were provided. [ABSTRACT FROM AUTHOR]

The regeneration of filter bags used in gas purification is considered. The behavior of the trapped dust layer and the filter material in regeneration is described. Regeneration systems in which internal circulation of the trapped dust within the filter is taken into account are discussed. Criteria permitting effective regeneration of various filter materials are presented. The key features of practical regeneration systems are identified. [ABSTRACT FROM AUTHOR]

• Transient cooling of the superheated metal plate by pulsed injection of a liquid jet. • Simultaneous measurement of the liquid film and the plate temperature distribution. • Cooling performance was evaluated from the wetting front and removed heat. • Thermal diffusivity and inertia of the metal affect the cooling performance. Pulse firing is one of the major operation modes of bipropellant thrusters for the attitude control of small-scale spacecrafts. In the pulse-firing mode, the operational range of the thruster depends on the deterioration of liquid film cooling performance. Because cooling performance is determined by the balance of heat removed by the liquid film and transferred to the manifold, the behavior and heat transfer characteristics of liquid films under the intermittent injection of liquid jets must be understood to enable a wider range of operational patterns. We conducted cooling tests on a superheated metal plate via the pulsed injection of a liquid jet for better understanding of the pulsed cooling process. Different injection patterns, including continuous injection, with the same injection quantity were examined on two types of metal plates (aluminum alloy and copper), because the thermal properties of metal plates affect both the heat transfer characteristics of the liquid film and temperature rise of the plate during the inter-pulse duration. The cooling process was evaluated based on the evolution of the liquid film on the metal plate and rear-side temperature of the metal plate. The evolution and temperature were simultaneously visualized using a high-speed camera and infrared camera, respectively. To link the liquid film state to the heat transfer process, the temperature and heat flux on the cooled surface were estimated by solving the inverse problem of three-dimensional transient heat conduction. The results indicate that the wetting front position corresponds to the position of the maximum temperature gradient. Additionally, the residual liquid film is consumed through the evaporation and the droplet dispersion related to the nucleate boiling. The effects of thermal inertia and diffusivity of the metal plate highlight the differences in the amount of heat removed by the liquid film. The heat removed by the liquid film during pulsed cooling exhibited a peak and was higher than that removed by continuous injection on the aluminum alloy plate. Less heat was removed under low-duty-cycle conditions, and the amount of heat removed by the liquid film was lower than that removed by continuous injection on the copper plate. [ABSTRACT FROM AUTHOR]

Shale gas has become an increasingly important source of natural gas ( CH 4 ) in the United States over the last decade. Due to its unconventional characteristics, injecting carbondioxide ( CO 2 ) to enhance shale gas recovery (ESGR) is a potentially feasible method to increase gas-yield while both affording a sink for CO 2 and in reducing the potential for induced seismicity. However, understanding of this issue is limited with few pilot field studies proposed. This study examines CO 2 -ESGR to better understand its feasibility and effectiveness. We explore the roles of important coupled phenomena activated during gas substitution especially vigorous feedbacks between sorptive behavior and permeability evolution. Permeability and porosity evolution models developed for sorptive fractured coal are adapted to the component characteristics of gas shales. These adapted models are used to probe the optimization of CO 2 -ESGR for injection of CO 2 at overpressures of 0 MPa, 4 MPa and 8 MPa to investigate magnitudes of elevated CH 4 production, CO 2 storage rate and capacity, and of CO 2 early-breakthrough and permeability evolution in the reservoir. For the injection pressures selected, CH 4 production was enhanced by 2.3%, 14.3%, 28.5%, respectively, over the case where CO 2 is not injected. Distinctly different evolutions are noted for permeability in both fractures and matrix due to different dominating mechanisms. Fracture permeability increased by ∼1/3 for the injection scenarios due to the dominant influence of CH 4 de-sorption over CO 2 sorption. CO 2 sequestration capacity was only of the order of 10 4 m 3 when supercritical for a net recovery of CH 4 of 10 8 m 3 . We investigated the potential of optimal CO 2 -pulsed injection to enhance CH 4 production (absolute mass recovered)-without the undesirable effects of CO 2 early-breakthrough and also minimum cost on CO 2 injection. This utilizes the competitive sorptive behavior between CH 4 and CO 2 , can also reduce the potential for induced seismicity hence the entire system can be near net neutrality in terms of its carbon and seismic footprint. [ABSTRACT FROM AUTHOR]

A numerical model is built to understand the transport phenomenon during the pulsed MOCVD process. The relations between the transport behavior of the precursors and the pulse duration for III, V, and pure H 2 pulses are studied. The results show that the mass fraction of precursors in the chamber during the III or V pulses becomes stable if they are longer in duration than a certain value. The duration of the pure H 2 pulse has a greater effect on particle generation than the duration of the III or V pulse. On the other hand, the V pulses can easily overtake the III pulses before reaching the substrate because of the lower Pe number of the NH 3. Using an III/V ratio of 1 results in more AlN particles in the high-temperature region during the H 2 pulse after the III pulse. By extending the duration of the H 2 pulse which follows the III pulse, there is a significant reduction in the generation of particles per cycle. When the duration of the H 2 pulse after the III pulse is increased to a certain time, the amount of particles generated after the III pulse becomes equal to that generated after the V pulse. When an even lower particle generation is required, the duration of H 2 pulses after the III and V pulses should be extended at the same time. [ABSTRACT FROM AUTHOR]

Abstract: Tungsten oxide films with various stoichiometries, undoped and hydrogen doped were deposited by heating a W wire at 660°C and at a base pressure of 13Pa set by various gasses (O2, N2, H2) or gas mixtures (N2–O2 10% in O2, forming gas, FG) and pulsed injection of O2 or H2. Using this method and dependent on the deposition conditions four classes of hot-wire (hw) tungsten oxide films were synthesized: i) stoichiometric (hwWO3), ii) oxygen deficient (sub-stoichiometric, hwWOx with x<3), iii) stoichiometric and hydrogen doped (hwWO3:H), and iv) sub-stoichiometric and hydrogen doped (hwWOx:H). Due to the pulsed injection of O2 the W wire re-oxidizes during deposition thus creating WO3 vapors continuously, so films deposited by this method do not suffer by thickness limitations and, moreover, exhibit high porosity. The optical properties of these classes of films, studied with spectroscopic ellipsometry (SE) measurements, differ substantially between them indicating corresponding differences in their electronic structures. So, hwWO3 films were semiconducting exhibiting a band gap near 3eV. Sub-stoichiometric hwWOx deposited with up to 2 injections of O2 were semi-metallic preserving some features of the electronic structure of the pure metal, while further injection of O2 leads to stoichiometric films. Fourier transform infrared spectroscopy and SE measurements indicated that hwWOx films contain H bonded with the O ions while in hwWO3:H and hwWOx:H the H is incorporated in films by direct bonding with the W ions. [Copyright &y& Elsevier]

The flame structure dynamics of strongly pulsed, turbulent diffusion flames were examined experimentally in a co-flow combustor. High-speed visual imaging and thermocouple measurements were performed to determine celerity, defined as as being the bulk velocity of a given flame puff structure in the large-scale, turbulent flame structures. Tests were conducted in normal gravity and microgravity with a fixed fuel injection velocity with a Reynolds number of 5,000 and also with a constant fueling rate where the Reynolds number ranged from 5,000 to 12,500. The celerity of strongly interacting flame puffs is as much as two times greater than for the case of isolated flame puffs. The amount of decrease in celerity at the visible flame tip due to the removal of buoyancy ranges from 7% to 11% in most cases, to as much as 36% for both fixed jet injection velocity and constant fueling rate. At the same time, the flame length is modestly affected by the removal of positive buoyancy, amounting to a decrease of as much as 20%. These observations hold for both fixed injection velocity and constant fueling rate cases. The observed increases in the flame puff celerity and the mean flame length with decreasing jet-off time, for a given injection time and gravity level, are consistent with a decreased rate of oxidizer entrainment into each flame puff structure due to increased flame puff interactions. A scaling argument accounts for the decrease of the flame puff celerity with downstream distance when both quantities are normalized by the appropriate injection conditions. The celerity, as characterized by the temperature measurement method, appears to be essentially unaffected by buoyancy at any given downstream location when appropriately scaled. The visual tracking method suggests a modest buoyancy effect at a given downstream distance, suggesting a subtle impact of buoyancy on the flame puff structures that does not impact the bulk motion. [ABSTRACT FROM AUTHOR]

The article reports on the dispersion of microparticles jet injected into a cross stream. The dispersion is controlled by interactions between flow structures and injected species. The purpose of the experiment was to find a way to control and optimize the dispersion of particles put into the cross stream. This was done by synchronizing the time of injection with the appearance of shear layer vortices. Particle packets, called puffs, were injected in time with the formation of the vortices, and it was discovered that particle dispersion can be regulated by pulsed injection after establishing the parameters of the system. This information can be applied in any field in which the dispersion of particles or droplets is important, such as fuel injections, and spray coating systems.

Abstract: This work is devoted to deposition of alumina–silica films using an innovative pulsed injection metal organic chemical vapour deposition technique and aluminium tri(iso-propoxide) (Al(i-OPr)3) and tetraethoxysilane (TEOS) as precursors. The deposited aluminium silicate films have been characterised by scanning electron microscopy, infrared spectroscopy, X-ray diffractometry and capacitance–voltage (C–V) measurements. The investigation of the deposition at different Si/Al ratios and substrate temperatures has shown that the growth rate increases with the increase of Al(i-OPr)3 proportion in solution and decreases as the proportion of TEOS increases. We have also shown that aluminium content in the film increases at lower deposition temperatures while silicon content increases at higher temperatures. The permittivity of the films determined from C–V measurements decreases with increasing substrate temperature. It was found that films deposited at substrate temperatures of 600 or 700 °C and with the highest Si/Al ratio have the lowest dielectric permittivity. This research should be useful for further development of MOCVD technology for the deposition of aluminosilicate-based dielectric materials with controlled dielectric permittivity. [Copyright &y& Elsevier]

Understanding the dynamics of sorption and bioavailability is crucial to the success of transport models as bioavailability often limits the complete bioremediation of contaminated soils. This paper examines the interplay between sorption and bioavailability with pulsed injection of nutrients based on a mechanistic model of microbially mediated reactive transport. We used a dimensionless parametric approach based on nondimensional groups such as the Damköhler and Peclet numbers to assess the relative importance of processes and rates. We consider case studies involving the biodegradation of carbon tetrachloride (CT) as well as a chemically induced degradation system to evaluate the effects of bioavailability. We first used these two cases to explore the effects of selectively activating the degradation terms in the aqueous and sorbed phases. The models for these two cases consistently predict that degradation is insensitive to retardation if degradation terms are not included for the sorbed phase. A specific mass removal rate was developed as an efficiency metric to explore the effects of pulsed nutrient injection on contaminant degradation and to estimate an optimal injection interval. The contaminant mass degraded per unit pumping was shown to be significantly higher for pulsed injection of substrates than with continuous injection. The presented results clearly indicate that considerations of bioavailability profoundly alter model predictions of degradation as well as parameter estimation results. [ABSTRACT FROM AUTHOR]

The effects of pH and ionic strength (salt concentration) on transmission of single protein human serum albumin (HSA) and human immunoglobulins (HIgG) through a 100 kDa molecular weight cut-off (MWCO) polyethersulfone membrane have been studied using a pulsed sample injection technique. Experimental results obtained clearly demonstrate the effectiveness of changing solution pH and ionic strength optimisation for selective transmission of HSA or HIgG. These also demonstrate the usefulness of pulsed injection experimental technique for the optimization of ultrafiltration processes. A pulse input carrier phase ultrafiltration (CPUF) was employed to fractionate a binary protein mixture of HSA and HIgG at low NaCl concentration, showing that it is feasible to separate the binary protein at optimised conditions. [Copyright &y& Elsevier]

The design of scramjet engines includes the investigation of minimally intrusive fuel delivery mechanisms which maximize jet fuel penetration and mixing. In subsonic crossflows it has been shown that pulsation of gaseous jets can improve jet penetration and mixing in comparison to unforced (steady) jets. Extensive investigations have already explored subsonic flow regimes for pulsed injection; however, only a limited number of experimental and numerical studies have been performed which investigate pulsed jets in a supersonic crossflow. This study presents fully three-dimensional (3D) scale-resolving simulations of steady and a sinusoidally pulsed jet (f = 16 kHz) using a wall modeled large eddy simulation approach to capture large-scale vortical structures in turbulent jet in supersonic crossflow and pulsed jet in supersonic crossflow. A block-structured, fully 3D turbulent scale resolving finite volume model was used to explore physics simulations of steady and pulsed jets in a supersonic crossflow. The results of the simulations presented show that sinusoidal pulsation of a gaseous hydrogen jet improves penetration and mixing over the steady jet when the momentum flux ratios are equivalent. [ABSTRACT FROM AUTHOR]

• Sensitive determination of nine N -nitrosamines with pulsed injection technique. • Comparative study of seven oxidation processes on N -nitrosamines degradation. • O 3 /H 2 O 2 AOP was the most effective method for N -nitrosamines removal. • NDMA was the most resistant spices which could be monitored as an indicator. • Re-formation of N -nitrosamines from the oxidized solution was negligible. N -nitrosamines are highly toxic disinfection byproducts (DBPs) formed in drinking water treatment process. Moreover, they could permeate reverse osmosis (RO) membrane during water recycling. Herein, an improved detection method for simultaneously determining 9 N- nitrosamines was established, and 7 kinds of oxidation processes were examined for degradation of the 9 N- nitrosamines. Compared with conventional injection mode, pulsed injection technique improved signal to noise ratio (SNR) and peak area of N- nitrosodimethylamine (NDMA) by 2.1 and 3.77 times, respectively. Low method detection limits (MDLs) were achieved ranging from 0.3 to 1.5 ng/L. Based on the improved detection method, simultaneous oxidation of 9 N- nitrosamines with UV irradiation/UV based advanced oxidation processes (AOPs), O 3 /O 3 based AOP, and permanganate and ferrate were comparatively investigated. Among these employed processes, O 3 /H 2 O 2 was the most effective approach for the elimination of N- nitrosamines, and 36.6% (NDMA)-91.4% (NDBA) removal efficiency was achieved. In comparison, ozonation merely removed less than 20% of N- nitrosamines (except NDphA for 29.3%). Compared to UV irradiation, the removal efficiency of N- nitrosamines was improved by almost 10% in UV/Cl 2 process, while the improvement in UV/peroxydisulfate (UV/PDS) process was not obvious. Permanganate and ferrate oxidations on N- nitrosamines removal were not significant. NDMA was found to be one of the most recalcitrant N- nitrosamines, therefore, it could be monitored as an indicator of N -nitrosamines in relevant treatment process. Finally, the risk of N -nitrosamines re-formation was found to be negligible when chloramination was applied after oxidation treatment. [ABSTRACT FROM AUTHOR]

• GC–MS/MS using pulsed split injection was used to determine 1,4-dioxane in cosmetics. • The UAE was used for preparing liquid samples without sample cleanup. • The method was fully validated using a variety of cosmetic matrices. • 1,4-dioxane was detected in 47 out of the 82 products ranged from 0.23 to 15.3 μg/g. 1,4-dioxane is a potential human carcinogen and contaminant produced during the manufacturing process from specific cosmetic ingredients, such as certain detergents and emulsifiers. As such, 1,4-dioxane is not identified on product ingredient labels. To assess the concentration of 1,4-dioxane in cosmetic products, a gas chromatography-tandem mass spectrometry (GC–MS/MS) method using pulsed split injection and electron ionization was developed and validated. For liquid cosmetic products such as shampoo and lotion, test portions were extracted using fast ultrasound-assisted extraction (UAE) procedure without sample cleanup. For solid products (e.g. beauty bars), a C 18 solid phase extraction (SPE) procedure was optimized to reduce potential interferences. The corresponding stable isotopically labeled analogue (1,4-dioxane-d 8) was selected as an internal standard to compensate for matrix effects and sample recovery. Method recovery experiments were performed in lotion, oil gel, hair detangler, bubble bath and beauty bar (solid) sample matrices with recoveries of 84–108% and relative standard deviations less than 5% at three spike concentrations. Method limits of detection (LOD) and quantification (LOQ) for 1,4-dioxane were determined at 0.2 μg/g and 0.5 μg/g, respectively. The method was successfully used to determine 1,4-dioxane in 82 leave-on and rinse-off cosmetic products marketed toward children including bath products, hair treatment, lotions, beauty bars, washes, shampoos, and other products. 1,4-dioxane was detected in 47 of the 82 products with an average concentration of 1.54 μg/g (range: 0.23–15.3 μg/g). The method can increase sample throughput and reduce matrix-induced interferences. [ABSTRACT FROM AUTHOR]

• An optical test rig is built to observe the high-pressure methane gas direct injection in a CVB. • A 3D numerical model of high-pressure methane injection in a CVB is verified by the test data. • The methane jet penetration has a two-stage behavior induced by the dynamic inner flow inside the nozzle. • The methane jet tip penetration and the penetration speed become saturated as the injection pressure rises high enough. • This jet saturation behavior is caused by inner flow saturation of Mach number and gas velocity inside the nozzle. For a direct injection natural gas engine, the fuel jets into the cylinder in cycles, and this gas pulsed injection process causes crucial effects on the combustion. This study presents an experimental investigation on the methane direct injection. An optical test rig is designed to observe the high-pressure methane jet into a constant-volume bomb (CVB), and a numerical model is built to analyze the gas flow. The methane jet has a two-stage feature. The gas jet characteristic parameters (the tip penetration, penetration speed, jet cone cover area) change rapidly in dynamic stage I, and become stable in stable stage II. The dynamic process inside the nozzle induces this two-stage gas jet flow. The inner methane flow experiences a time delay from the inlet to the outlet, and the gas jet undergoes the same time delay to maintain stable. Furthermore, the injection pressure has great effects on the gas jet. As the injection pressure rises high enough, the gas jet saturation behavior occurs, and it is caused by inner flow saturation of Mach number, Reynolds number and gas velocity inside the nozzle. It is not necessary to increase injection pressure as high as possible for improving the gas jet characteristics. [ABSTRACT FROM AUTHOR]