Construction of a novel aminofluorene-based ratiometric near-infrared fluorescence probe for detecting carboxylesterase activity in living cells.

Herein, we constructed a novel aminofluorene-based fluorescence probe (FEN-CE) for the detection of carboxylesterase (CE) in living cells by a ratiometric near-infrared (NIR) fluorescence signal. FEN-CE with NIR emission (650 nm) could be hydrolyzed specifically by CE and transformed to FENH with the release of the self-immolative group, which exhibited a red-shifted emission peak of 680 nm. In addition, FEN-CE showed high selectivity for CE and was successfully used in the detection of CE activity in living cells through its ratiometric NIR fluorescence signals.

Study of Sintering Behavior of Methane Hydrate Particles on the Wall Surface.

The sintering of hydrate aggregates on the pipe wall is a major form of hydrate deposition. Understanding the sintering behavior of hydrates on the wall is crucial for promoting hydrate safety management and preventing pipeline blockage. However, limited research currently exists on this topic. In this study, the cohesive force strength of hydrate particles on the wall surface under different conditions was directly measured using a high-pressure micromechanical force device (HP-MMF). Subsequently, the effects of subcooling and glycine on the cohesive force were investigated. The results indicate that the cohesive force is influenced by different growth states during the process of free water on the wall surface gradually growing into hydrate. Three states with larger measured values during the growth process were selected for research. Observation showed that increased subcooling strengthened sintering by accelerating the growth rate of the hydrate film, resulting in a significant increase in cohesive force. The role of glycine in the methane hydrate system was then evaluated. Glycine was found to reduce the degree of sintering by reducing the growth rate of the hydrate film, thereby decreasing the cohesive force. The optimal concentration in the system was determined to be 0.25 wt %. Moreover, compared with low subcooling (1 °C), glycine had a better effect at high subcooling (5 °C). At 5 °C subcooling and the optimal concentration, the cohesive force in the wall droplet state decreases from 677.38 to 489.02 mN/m, the cohesive force at the low-saturation state decreases from 951.79 to 543.32 mN/m, and the cohesive force at the high-saturation state decreases from 1194.95 to 641.76 mN/m. These findings contribute to a better understanding of the cohesive force behavior of gas hydrate on the inner wall of the pipeline and provide basic data for reducing the risk of hydrate blockage.

Experimental study of the effects of a magnetic field/magnetic field-ferromagnetic nanocomposite pour point depressant on wax deposition.

A magnetic field and pour point depressant, as a new avenue for improving the submarine pipeline flow of waxy oils, has attracted increasing attention along with the development of efficient wax mitigation techniques. Although advances have been made recently in understanding the rheological behavior and crystallization properties of waxy oils, the effect of magnetic field and pour point depressants on wax deposition remains an open question. In this work, a ferromagnetic nanocomposite pour point depressant (FNPPD) was prepared. The variations in wax deposition mass and component under the effect of different magnetic treatments and magnetic field-FNPPDs were investigated using cold fingers and high-temperature gas chromatography. It was evident that both the high-intensity and high-frequency magnetic fields generated by the magnet and magnetic coil can effectively reduce the deposition mass and have a long-term magnetic history effect. The synergistic effect of magnetic fields and FNPPDs concurrently reduced the thickness/mass and wax content in the deposition layer, as compared to the individual use of magnetic fields or FNPPDs. The wax precipitation properties and wax crystal morphology of waxy oils under the action of the magnetic field were characterized by differential scanning calorimetry, focused beam reflectance measurement and polarizing microscopy experiments, and the mechanism of the magnetic field was elaborated from the perspective of crystallization kinetics by combining the fitting analysis of Avrami and size-independent growth model.

Water Droplets Tailored as Wax Crystal Carriers to Mitigate Wax Deposition of Emulsion.

This study explores how the micro-distribution change of wax crystals from the continuous oil phase to the oil-water interface mitigates the macro wax deposition of an emulsion. Two types of interfacial actions between wax crystals and water droplets, interfacial adsorption and interfacial crystallization, which were induced by two different emulsifiers, sorbitan monooleate (Span 80) and sorbitan monostearate (Span 60), respectively, were detected by differential scanning calorimetry and microscopy observation. The wax interfacial crystallization promoted by Span 60 resulted in the wax being nucleated directly at the oil-water interface prior to the continuous oil phase, conferring the nascent wax crystals and water droplets to be combined as coupled particles. The utilization of the wax interfacial crystallization behavior to hinder wax deposition of an emulsion was further explored. When the coupled wax crystal-water droplet particles were formed during the wax deposition process, water droplets acted as wax crystal carriers, entraining these nascent wax crystals to disperse in the emulsion, which significantly reduced the amount of wax crystals available to form the network of the deposit. In addition, this change also led to the basic structural units in the wax deposit evolving from wax crystal clusters/networks to water droplet flocs. The study elucidates that through adjusting the dispersion of wax crystals from the oil phase to the oil-water interface, water droplets could act as a functional component to tailor the properties of the emulsion or resolve related flow and deposition problems in pipeline transportation.

Study on the growth kinetics of methane hydrate in pure water system containing ZIF-8.

The hydrate formation rate is the key to the implementation of solid gas storage and transportation technology by the hydrate method. As a MOF material with strong hydrothermal stability, ZIF-8 has been proved to play a significant role in promoting the nucleation and growth of hydrate. However, the growth kinetics promotion mechanism and growth law of methane hydrate in the ZIF-8 promoter system have not been clarified at present. Therefore, the growth kinetics experiment of methane hydrate in the ZIF-8 promoter system was carried out in a high-pressure visualization reactor to systematically study the effects of the ZIF-8 concentration, undercooling degree, and pressure on the growth law of methane hydrate. The experimental results showed that: (1) the concentration of ZIF-8 had a significant shortening effect on the induction period of methane hydrate. With the increase in the ZIF-8 concentration, the induction time of methane hydrate was shortened from 5.85 h to 0.85 h. The methane gas consumption showed a gradually increasing trend at first, and then with the reaction going on, a dense hydrate film was formed at the gas-liquid interface, which increased the mass transfer resistance, resulting in the increase in the methane gas consumption gradually becoming stable. There were four stages in the growth process of hydrate, namely rapid formation, slow formation, secondary formation, and end formation and the optimal dosage of ZIF-8 promoter exists, and the optimal critical specific content was 0.02 mg mL-1. (2) With the increase of undercooling, the induction time of methane hydrate decreased significantly, and the increase in the methane consumption also showed an increasing trend at first and then decreased. (3) With the increase of the system pressure to 7 MPa, the induction time of methane hydrate decreased from 1.02 h at 6 MPa to 0.2 h at 7 MPa, and the decrease rate was 80.8%, which was mainly due to the presence of "OPEN GATE" in the ZIF-8 accelerator. With the increase of the system pressure, the pore opening of the ZIF-8 material increased, the adsorption of methane increased, and the nucleation and growth of methane hydrate were promoted.

Evolution of morphology and cohesive force of hydrate particles in the presence/absence of wax.

In the exploitation of deep-sea oil and gas resources, the multiphase production and transportation process is frequently plagued by pipeline blockage issues. Especially when hydrates and wax coexist simultaneously, the viscosity and plugging tendency of multiphase flow systems will synergistically increase. Understanding the evolution of morphology of hydrate particles and the agglomeration characteristics of hydrate particles in the presence or absence of wax crystals is crucial to flow assurance industry. With the assistance of a visualized reactor equipped with a three axis moving platform, microscopic images of cyclopentane hydrate during hydrate growth were obtained, and the cohesive force between hydrate particles was measured. It was found that during the hydrate growth on wax-free water droplets, the untransformed water inside the particles gradually wetted the surface of the particle. With the increase in temperature and contact time, the shell of hydrate particles changed from solid and rough to smooth and moist. The cohesive force measured in this work ranges from 3.14 ± 0.52 to 11.77 ± 0.68 mN m-1 with different contact times and temperature. When the contact time was 0 s and 10 s, the cohesive force between particles increased first and then stabilized with temperature. When the contact time was 20 s, the cohesive force was greater than the first two cases and showed an overall stable trend. An interesting phenomenon was also discerned: a large water bridge between particles formed during their separation process. For the wax-containing system, it required a longer time for water droplets to be converted into hydrate particles than that for wax-free systems. After wax participated in hydrate growth, hydrate particles showed the properties of elasticity and stickiness, which resulted in a larger liquid bridge between hydrate particles after their contact. It was suggested that wax crystal would alter the shell structure of hydrate particles, and change the surface properties of hydrate particles and the formation process of the liquid bridge, leading to significant and rapid increase in the cohesive force.

Study on the Adhesion Force between Wax Crystal Particles and Hydrate Particles.

In this work, to solve the problem of pipeline blockage caused by the accumulation of hydrate particles and wax particles and to explore the interaction characteristics of adhesive force between gas hydrate particles and wax particles as well as droplets, a high-pressure triaxial mobile device was used to measure the adhesion strength between cyclopentane hydrate particles and different commonly seen phases in the pipeline, including cyclopentane hydrate particles themselves, liquid droplets, and wax crystal particles. These experiments were conducted at different temperatures. The results showed that the adhesion between hydrate and wax particles was decreased with the increase in temperature; this is because the wax is amorphous, the heat absorbed when the temperature rises only increases its average kinetic energy, and the stronger the kinetic energy, the lower its viscosity, resulting in reduced adhesion between particles. Meanwhile, this adhesion was also affected by the concentration of wax. As the wax concentration increased from 1 to 5.32 wt % and then to 8.14 wt %, the adhesion between hydrate and wax particles was first decreased and then increased. This was because when the wax crystal concentration was below 5 wt %, a higher wax molecule concentration meant a more hydrophobic surface, which restricted the formation of a capillary liquid bridge between particles and thus reduced the interforce between wax crystal particles and hydrate particles. When the wax crystal concentration was between 5 and 8 wt %, the change of hydrophobicity was no longer the dominating factor, the increase in wax concentration blocked the hydrate molecular diffusion path, which caused a higher hydrate viscosity, therefore leading to a decreased hydrate molecular diffusion rate and a reduced conversion rate of the liquid bridge in hydrates, the lower conversion rate could subsequently lead to the increasing size of micropores in the hydrate shell, and adhesion between particles was increased.

Experimental Study of the Growth Kinetics of Natural Gas Hydrates in an Oil-Water Emulsion System.

In order to explore the growth kinetics characteristics of NGH (natural gas hydrate) in an oil and gas mixed transportation pipeline and ensure the safe transportation of the pipeline, with the high-pressure hydrate experimental loop, an experimental study on the growth characteristics of NGH in an oil-water emulsion system was carried out, and the effects of pressure, flow rate, and water cut on the hydrate induction time, gas consumption, consumption rate, and hydrate volume fraction were explored, and important experimental rules were obtained. The experiment was divided into three stages: in the rapid formation stage of the hydrate, the temperature and gas consumption rose sharply, and the pressure dropped suddenly. The induction time decreased with the increase of pressure, flow rate, and water cut. The induction time of 6 MPa was 86.13 min, which was shortened by 39.68% compared with the induction time of 142.8 min of 5 MPa. The induction time of 1500 kg/h was 88.27 min, which was shorter by 13.91% than that 102.53 min of 550 kg/h. The induction time of 20% water cut was 58.53 min, which was shorter by 13.99% than that 68.4 min of 15% water cut. The gas consumption and hydrate volume fraction were both increased with the increase of pressure and water cut and decreased with the increase in the flow rate. In the whole process of the formation of NGH, the consumption rate first increased and then decreased. The pressure-drop and apparent viscosity increased with the increase of hydrate volume fraction in a certain range. The sensitivity analysis of hydrate induction time based on the standard regression coefficient method showed that the initial pressure played a major role, followed by the flow rate and the water cut. Based on the sensitivity analysis of hydrate volume fraction by the gray correlation method, it was found that the hydrate volume fraction had the closest relationship with the initial pressure, followed by the flow rate and the water cut. Finally, the empirical formulas of induction time and hydrate volume fraction in an oil-water emulsion system were established.

Study on the Formation Characteristics of CO2 Hydrate and the Rheological Properties of Slurry in a Flow System Containing Surfactants.

Adding low dosage hydrate inhibitors to the hydrate systems makes the generated hydrate particles more uniformly dispersed in the liquid phase, which can significantly reduce the hydrate accumulation and blockage in oil and gas pipelines. The effect of surfactant hydrophile-lipophilic balance (HLB) values on hydrate flow characteristics was studied with a flow loop. The experimental results showed that there was a critical HLB value. When the HLB value was 4.3-9.2, it had an inhibitory effect on the hydrate induction time, and when the HLB value was greater than 10.2, it had a promoting effect. The hydrate volume fraction increased gradually with the increase in the HLB value, while the slurry apparent viscosity decreased with the increase in the HLB value. It was also found that different types of surfactants all showed the effects of anti-agglomerant and dispersion, which can obviously improve the flow of the hydrate slurry. Finally, the analyzed results showed that the hydrate slurry exhibited shear-thinning behaviors that can be identified as a pseudoplastic fluid based on the Herschel-Bulkley rheological model, and the functional relationship between the rheological index and the solid phase hydrate volume fraction was obtained using the fitting method. This study can provide a reference for the preparation of high-efficiency hydrate anti-agglomerants.

Isoliquiritigenin alleviates P. gingivalis-LPS/ATP-induced pyroptosis by inhibiting NF-κB/ NLRP3/GSDMD signals in human gingival fibroblasts.

OBJECTIVE: To investigate whether pyroptosis is induced by Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS)/ adenosine triphosphate (ATP) through NF-κB/NLRP3/GSDMD signaling in human gingival fibroblasts (HGFs) and whether isoliquiritigenin (ISL) alleviates pyroptosis by inhibition of NF-κB/NLRP3/GSDMD signals. DESIGN: Periodontitis was optimally simulated using a combination of P. gingivalis-LPS and ATP. The expression levels of genes and proteins of NF-κB, NLRP3 inflammasome, GSDMD, and IL-1ß was characterized by qRT-PCR, western blotting and ELISA. The 2',7'­dichlorodihydrofluorescein diacetate fluorescence probe was used to determine the intracellular ROS level. Hoechst 33342 and PI double staining, cytotoxicity assay, and caspase-1 activity assay were used to confirm the influence of ISL on pyroptosis in P. gingivalis-LPS/ATP-treated HGFs. RESULTS: P. gingivalis-LPS/ATP stimulation significantly promoted expression of NF-κB, the NLRP3 inflammasome, GSDMD, and IL-1ß at gene and protein levels. The proportion of membrane-damaged cells, caspase-1 activity, and the release of lactate dehydrogenase (LDH) were also elevated. However, pretreatment with ISL observably suppressed these effects. CONCLUSIONS: P. gingivalis-LPS/ATP induced pyroptosis in HGFs by activating NF-κB/NLRP3/GSDMD signals and ISL attenuated P. gingivalis-LPS/ATP-induced pyroptosis by inhibiting these signals. This evidence may provide a new direction for the treatment of periodontitis.

Hypoxia and Porphyromonas gingivalis-lipopolysaccharide synergistically induce NLRP3 inflammasome activation in human gingival fibroblasts.

OBJECTIVE: To investigate the effects of hypoxia and Porphyromonas gingivalis- lipopolysaccharide (P. gingivalis-LPS) on activation of the NACHT leucine-rich repeat protein 3 (NLRP3) inflammasome in human gingival fibroblasts (HGFs). DESIGN: Periodontitis was optimally simulated using a hypoxic concentration of 1%. HGFs were stimulated using P. gingivalis-LPS (1.0 µg/ml) in normoxia and hypoxia for 3 h and 6 h, respectively. The expression levels of genes and proteins of hypoxia-inducible factor-1α (HIF-1α), interleukin-1ß, gasdermin D (GSDMD) and the NLRP3 inflammasome, including NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), caspase-1 and its activated forms, were measured using quantitative real-time polymerase chain reaction and western blot. ELISA was used to detect and determine levels of the inflammatory factor interleukin-1ß in cell supernatants. Lactate dehydrogenase (LDH) release assay, caspase-1 activity assay and Hoechst 33342/Propidium Iodide (PI) staining were performed to further verify the presence of pyroptosis. RESULTS: The NLRP3 inflammasome (i.e., NLRP3, ASC, caspase-1) was not affected by individual stimulation using P. gingivalis-LPS or hypoxia. However, the combination of both hypoxia and P. gingivalis-LPS stimulation significantly enhanced inflammasome activation and promoted the expression of interleukin-1ß, gasdermin D and HIF-1α at gene and protein levels; PI positive cells and the release of LDH were also elevated. CONCLUSION: Hypoxia and P. gingivalis-LPS synergistically induced NLRP3 inflammasome activation in HGFs, and subsequently high levels of interleukin-1ß and GSDMD-mediated pyroptosis can cause an HGF inflammatory response, which plays an important role in the pathogenesis of periodontitis.

Study on the Kinetic Process of Asphaltene Precipitation during Crude Oil Mixing and Its Effect on the Wax Behavior of Crude Oil.

As an important component of crude oil, asphaltene precipitation and deposition are harmful to petroleum production and processing. In previous research, the impacts of asphaltene precipitation on crude oil characteristics were preliminarily explored. In this paper, by mixing different types of crude oil, the dynamic process of asphaltene precipitation and its effect on the crystallization and gelation behaviors of mixed crude oil were in-depth analyzed and discussed using the high-speed centrifugation technique, microscopic observation, differential scanning calorimetry (DSC) thermal analysis, and rheological test. The results showed that the asphaltene precipitation mainly occurred in the early stage of crude oil mixing and was influenced by crude oil composition. As the precipitation time increased, the driving force for asphaltene precipitation was gradually weakened until a dynamic equilibrium between asphaltene precipitation and dissolution was reached. Meanwhile, once the asphaltene precipitation occurred, the crystallization and gelation processes of crude oil were significantly affected. It was discovered that the change in the existing state of asphaltenes due to their precipitation is an important factor affecting the interaction of asphaltenes and waxes, which is critical for the technological development of oil and gas flow assurance.

Study on the kinetic characteristics of gas hydrate in the dioctyl sodium sulfosuccinate system.

Surfactants promote the production of hydrates, which provide a possibility for the industrialization of hydrate technology. In this paper, methane and CO2 hydrate formation experiments were carried out, respectively, with surfactant-dioctyl sodium sulfosuccinate (DSS) using a visual experimental apparatus at a constant pressure. This study explored the influence of the surfactant dosage, experimental pressure, and subcooling temperature on the dynamic characteristics of hydrate formation. The results indicated that a small amount of surfactant had a significant promotion effect on the formation of hydrate, i.e., 600 mg L-1 DSS shortened the induction time of methane hydrate by 60 times and that of CO2 hydrate by 2.4 times, while it increased the formation rate by 3.4 times. Due to the weak acidity of the CO2 solution, the effect of DSS on CO2 hydrate formation was significantly reduced. The DSS concentration had a limited effect on changing the rate of the gas storage capacity of the two hydrates. Compared with other surfactants reported in the literature, DSS showed a better promotion effect on hydrate formation. This study reveals the mechanisms of interfacial tension reduction and the promotion of hydrate growth adhering to the wall using a surfactant with a double-chain structure, which further enriched the hydrate-promoting mechanism, and provides experimental data and a theoretical research basis for the study of kinetic characteristics of hydrates in surfactant systems.

Study on the decomposition mechanism and kinetic model of natural gas hydrate slurry in water-in-oil emulsion flowing systems.

Hydrate slurry decomposition in flow systems is a significant subject that involves flow assurance and development of marine natural gas hydrates. Firstly, the decomposition mechanism of hydrate slurry is studied in this work, and it is proposed that desorption of the gas from the surface of the decomposed hydrate particles might be the main reason for the coalescence of particles and water droplets during the hydrate slurry decomposition. Secondly, a hydrate slurry decomposition kinetic model comprehensively considering the influencing factors (i.e., the intrinsic kinetics, heat and mass transfer) is proposed in this work, based on the classic intrinsic kinetic model and the hydrate slurry dissociation experiments conducted in a flow loop system. The fugacity difference is used as the driving force for the hydrate decomposition, and the influence of particle coalescence, and heat and mass transfer is also considered. The effect of the heat and mass transfer is coupled with the apparent decomposition reaction rate constant. Meanwhile, the time-dependent interfacial parameters would significantly impact on the hydrate dissociation rate, which are considered to enhance the predictive precision of the decomposition kinetic model. Further, the integrated decomposition kinetics model proposed in this paper could well describe the trends of the amount of released gas and the dissociation rate of the experimental flow systems. Through combining the experimental results of the hydrate slurry decomposition, the decomposition parameters under actual flowing conditions were obtained.

Study of the Comprehensive Kinetic Model of Natural Gas Hydrate Formation in a Water-in-Oil Emulsion Flow System.

Hydrate growth is influenced by many factors, including thermodynamics, kinetics, mass and heat transfer, and so on. There is thus a practical significance in establishing a model that comprehensively considers these influencing factors for hydrate crystal growth in multiphase transportation pipelines. On this basis, this paper presents a more practical and comprehensive bidirectional growth model of hydrate shells for an actual pipeline system. Thermodynamic phase equilibrium theory and water molecule penetration theory are applied in this model to develop a method for calculating the concentration change of hydrate-forming guest molecules and the permeation rate of water molecules. The temperatures on both sides of the hydrate shell are predicted by the heat transfer model. Simultaneously, decreasing the mass transfer coefficient with continuous hydrate growth is used to describe the problem in which the mass transfer efficiency decreases with a thickened hydrate shell. Then, the hydrate growth kinetic parameters of the pipeline system are optimized according to hydrate growth experiments conducted in a high-pressure flow loop and the microscopic characteristics of the particles were provided using the PVM and FBRM probes. The improved hydrate growth model can improve the prediction accuracy of hydrate formation in slurry systems.

Study on the Operation Safety and Reliability of a Waxy Hot Oil Pipeline with Low Throughput Using the Probabilistic Method.

When the hot oil pipeline is running at a low throughput, it easily enters into an unstable condition, which seriously threatens the safety of the hot oil pipeline operation. In this study, the unsteady heat transfer and flow mathematical models for the hot oil pipeline system were established first by comprehensively considering the uncertainty of parameters during pipeline operation, such as the operating parameters (throughput and oil temperature), physical properties of crude oil (freezing point, viscosity, and thixotropic parameters), and environmental parameters (buried deep soil temperature and soil thermal conductivity). Then, the efficient Latin hypercube sampling (LHS) stochastic numerical algorithm was applied and further developed to quantitatively describe the operation safety of hot oil pipelines with low throughput in the form of probability. On the basis of the abovementioned research, the qualitative relationship between pipeline flowrate and friction loss is obtained. Finally, taking an actual crude oil pipeline as an example, the failure probabilities of the pipeline under different operating conditions were analyzed in detail. Combined with the target safety level of pipeline operation, the minimum allowable throughput of pipelines was determined. This study revealed the flow and heat transfer law of hot oil pipelines with low throughput and determined its operation safety and reliability under different operating conditions.

Biological effects on tooth root surface topographies induced by various mechanical treatments.

The cleaning and physicochemical properties on tooth root biointerfaces are pivotal for periodontal healing. Herein, this work investigated the impact of multi-treatment on the physicochemical features of tooth root surfaces and the responsive behavior of human gingival fibroblasts (hGFs). It was found that the combination of various mechanical treatments significantly affects the topographical pattern and size as well as wettability on tooth root surfaces. Furthermore, biological experiments revealed that hGF behaviors (i.e., cell adhesion, shape, spreading, arrangement, and viability) were regulated by the topography and wettability of tooth root surfaces. Also, there was no significant difference in the protein expression of NLRP3 inflammasome and IL-1ß in hGFs among tooth root surfaces under various treatments. This study provides new insights to efficiently remove the dental calculus and to understand the interaction between the tooth root interface and cell, which could guide the clinical operation and thereby is more conducive to periodontal recovery.

A combination of mupirocin and acidic fibroblast growth factor for nipple fissure and nipple pain in breastfeeding women: protocol for a randomised, double-blind, controlled trial.

INTRODUCTION: Nipple fissure and nipple pain are common complaints among breastfeeding mothers. Studies found that mupirocin was effective in preventing and treating infections of damaged nipple and nipple pain. Acidic fibroblast growth factor (aFGF) plays an important role in wound healing. However, current evidence on the efficacy and safety of mupirocin plus aFGF for nipple fissure and nipple pain in breastfeeding women is inconclusive due to the lack of well-designed randomised controlled trials on this topic. The purpose of this study is to test the hypothesis that mupirocin plus aFGF is more effective than mupirocin alone for nipple fissure and nipple pain in breastfeeding women. METHODS AND ANALYSIS: This study is a randomised, double-blind, single-centre, parallel-group clinical trial. A total of 120 breastfeeding women with nipple fissure and nipple pain will be randomly assigned to either mupirocin plus aFGF group or mupirocin plus placebo group according to a computer-generated random allocation sequence. The treatment period lasts 14 days. The primary outcome is nipple pain intensity measured by the Visual Analogue Scale on day 14 during the treatment period. Secondary outcome measures include time to complete nipple pain relief, changes in the Nipple Trauma Score, time to complete healing of nipple trauma, quality of life measured by the Maternal Postpartum Quality of Life (MAPP-QOL) Questionnaire, the frequency of breast feeding, the rate of breastfeeding discontinuation, weight change in infants and adverse events. ETHICS AND DISSEMINATION: The study has gained approval from the Ethics Review Committee of Tianjin Central Hospital of Gynaecology Obstetrics on 22 January 2018 (approval no. 2018KY001). We plan to publish our research findings in a peer-reviewed academic journal and disseminate these findings in international conferences. This study has been registered with the Chinese Clinical Trial Registry. TRIAL REGISTRATION NUMBER: ChiCTR1800017248.

Study on methane hydrate formation in gas-water systems with a new compound promoter.

The effects of a new promoter on the growth kinetics of methane hydrates were investigated using a visualized constant-pressure autoclave. The experimental results show that when the 1#, 2# and 3# unit promoter was compounded at a ratio of 2 : 1 : 1, the induction time was shortened greatly from 30 h to 0.64 h compared to the no promoter situation. Meanwhile, there was a larger amount of hydrate formation, and final hydrate volume fraction was 83.652%. Then, the hydrate formation characteristics under different additive dosages (500 ppm, 1000 ppm, 2000 ppm, 5000 ppm) and different subcooling degrees (2.5 °C, 3.5 °C, 4.5 °C, 5.5 °C, 6.5 °C) were investigated. The new promoter at these 4 concentrations could effectively shorten the induction time. And the higher the concentration, the smaller the induction time (0.22 h at 5000 ppm). It was also found that gas consumption and hydrate production rate increased first and then decreased with increasing promoter dosage. Finally, the optimal dosage was determined to be 2000 ppm, at which the induction time was shortened to 0.52 h, and the final hydrate volume fraction was 85.74%. Under the dosage of 2000 ppm and the subcooling degree of 6.5 °C, the shortest induction time (0.29 h) and the maximum formation rate (20.950 ml h-1) were obtained among all the experimental conditions in this work. Moreover, the greater the subcooling degree, the faster the hydrate nucleation, and the shorter the induction time. However, if the subcooling degree was too high, a hydrate layer formed rapidly at the gas-liquid interface in the autoclave, which would hinder hydrate formation and lead to the reduction of hydrate volume fraction to 60.153%. Therefore, a reasonable selection of the proportioning of promoters, dosage of the promoter and formation temperature could significantly promote the formation of hydrates. The findings in this work are meaningful to hydrate associated applications and can provide useful references for the selection of hydrate promoters.

Experimental study of growth kinetics of CO2 hydrates and multiphase flow properties of slurries in high pressure flow systems.

The formation and accumulation of hydrates in high pressure oil and gas pipelines bring great risks to field development and deep-water transportation. In this paper, a high pressure flow loop equipped with visual window was used to study the growth process of hydrates in a pipe flow system and slurry flow characteristics. Deionized water, industrial white oil and CO2 were selected as the experiment medium. A series of experiments with different initial pressures (2.5-3 MPa), liquid loads (7-9 L), flow rates (25-35 kg min-1) and water cuts (60-100%) were designed and carried out. Specifically, hydrate formation and slurry flow characteristics in two different systems, pure water and oil-water emulsion system, were compared. Both of the systems experienced an induction stage, slurry flow stage and followed by a plugging stage. Although hydrate growth gradually ceased in the slurry flow stage, plugging still occurred due to the continuous agglomeration of hydrates. Visual observation showed that there were obvious stratification of the oil-water emulsion systems at the later time of slurry flow stage, which directly resulted in pipe blockage. The hydrate induction time of the flow systems gradually decreased with the increasing initial pressure, initial flow rate and water content. And the induction time tended to decrease first and then slowly increase with the increasing liquid loading. For emulsion systems, the apparent viscosity and friction coefficient of the hydrate slurry increased with the increasing water content, indicating that there were higher plugging risks compared to the pure water systems. Moreover, the results of sensitivity analysis showed that the water content was the main factor affecting the hydrate induction time, followed by the influence of liquid carrying capacity and flow rate, and the initial pressure had the least influence on the induction time. Conclusions obtained in this paper can provide some reference not only for the prevention and management of hydrates in pipelines, but also for the application of CO2 hydrate as a refrigerant.