Accumulation Of Bubbles Research Articles

Malignant Edema in Horse by Clostridium perfringens Type A

Background: Malignant edema is one of the terms used to designate severe necrotizing syndromes in soft tissues by Clostridium spp. which are potentially fatal in farm animals. These species are responsible for myonecrosis, belonging to the group of histotoxic clostridia, and may also culminate in toxemia with the worsening of the lesions. These clostridia and their spores require a gateway such as wounds on mucous membranes or skin, which may occur due to shear, tail cut, injuries during delivery, castration or injections by contaminated needles. This report aims to describe the clinical-pathological findings of a case of malignant edema caused by C. perfringens type A in an equine.Case: A female equine, undefined breed, used as traction animal, had a history of abdominal pain. According to the requisitioning veterinary, the tutor reused needles for medication. On palpation, a compact mass was noticed in the pelvic flexure, as well as edema on the region of head and neck with crackling areas. After surgical intervention for compactation correction, the animal did not show anesthetic recovery and was submited to euthanasia. Tissue samples were collected, fixed in 10% buffered formalin solution, routinely processed for histopathology and stained with hematoxylin and eosin and Gram stain. Samples of serous-sanguineous edema fluid and fragments of the abdominal muscles and neck were collected. The samples were kept under refrigeration and sent for microbiological culture. Necropsy showed the subcutaneous region of the pectoral was markedly gelatinous and yellowish (edema) and subcutaneous emphysema characterized by accumulation of serous-sanguineous fluid and gas bubbles. In microscopy, we verified fibrous-haemorrhagic, emphysematous, suppurative and diffuse superficial histiocytic necrotizing cellulitis and myositis. Gram-positive bacillary aggregates were observed in spleen and subcutaneous sections. Colony suggestive of Clostridium perfringens were submitted to PCR for confirmation of identity followed by genotyping. Lastly, C. perfringens type A was isolated from the muscle fragments and serosanguinolent liquid collected.Discussion: In the present study, the diagnosis of malignant edema caused by Clostridium perfringens type A in an equine was confirmed by the clinical-pathological findings added to the isolation and genotyping of the agent from fragments of injured muscle. Although C. perfringens has been reported in cases of clostridial myositis in horses in the United States, in Brazil there are only reports of sporadic cases associated with C. septicum, C. novyi and C. chauvoei in this species. In histotoxic cases by C. perfringens, alpha toxin is known to be the main virulence factor involved, causing destruction of the phospholipid membrane of erythrocytes, endothelial cells, leukocytes and muscle fibers. As consequence, there is an increase in the vascular permeability of capillaries and, with the spread of the infection, there is production of inflammatory edema with serosanguineous exudate and gas. Typically, anatomopathological findings are characterized by increased volume of the affected region associated with edema with bloody fluid and rancid odor, gas bubbles in the subcutaneous tissue, and fasciae associated or not with necrotic myositis. It is assumed that a contaminated needle injection, performed during the treatment of colic symptoms on the property has been the gateway to infection. The clinical course of clostridial infection in horses is considered acute, ranging from 24 to 48 h. In this case, was observed the animal with signs of cervical and pectoral edema still in the property, a day before euthanasia. This is the first study to confirm Clostridium perfringens as a cause of gas gangrene in horses in Brazil.

Influence of the Diffusion Media Structure for the Bubble Distribution in Direct Formic Acid Fuel Cells

Direct formic acid fuel cells (DFAFCs) have received considerable attention because they can generate a higher power density compared to other direct liquid fuel cells. However, when generated CO2 bubbles are retained in the anode’s porous transport layer (PTL), the performance of the DFAFCs deteriorates. The gas–liquid two-phase flow behavior within a PTL is not clear; therefore, in this work the power-generation characteristics of DFAFCs using two types of PTL, carbon paper and carbon cloth, were investigated. It was found that the maximum current density was approximately 60 mA cm−2 higher with the carbon cloth than with the carbon paper. The CO2 bubble distribution in the anode’s PTLs was visualized by X-ray computed tomography and discuss the effects of the bubbles on the power-generation performance of DFAFCs. We found that interstices in a carbon-cloth PTL provided pathways for bubble migration and release to the channel, so that the bubbles did not deteriorate the power output. Bubble accumulation in a carbon-paper PTL led to a drop in power output, confirming that the structure of the PTL and the CO2 bubbles affect the power-generation characteristics.

Effect of Vertical Vibration on the Mixing Time of a Passive Scalar in a Sparged Bubble Column Reactor

The present study used a sparged bubble column to study the mixing of a passive scalar under bubble-induced diffusion. The effect of gas superficial velocity (up to 69 mm/s) and external vertical vibrations (amplitudes up to 10 mm, frequency <23 Hz) on the mixing time scale were investigated. The bubble-induced mixing was characterized by tracking the distribution of a passive scalar within a sparged swarm of bubbles. Void fraction and bubble size distribution were also measured at each test condition. Without vibrations (static), the bubble column operated in the homogenous regime and the mixing time scale was insensitive to void fraction, which is consistent with the literature. In addition, the temporal evolution of the static column mixing was well approximated as an error function. With vertical vibrations at lower amplitudes tested, the bubble-induced mixing was restrained due to the suppression of the liquid velocity agitations in the bubble swarm wake, which decelerates mixing. Conversely, at higher amplitudes tested, vibration enhanced the bubble-induced mixing; this is attributed to bubble clustering and aggregation that produced void fraction gradients, which, in turn, induced a mean flow and accelerated the mixing. The vibration frequency for the range studied in the present work did not produce a significant effect on the mixing time. Analysis of the temporal evolution of the concentration of the passive scalar at a fixed point within the column revealed significant fluctuations with vibration. A dimensionally reasoned correlation is presented that scales the non-dimensional mixing time with the transient buoyancy number.

Thermocapillary migration of droplets and bubbles in a viscous liquid (review)

Investigation of the process of accumulation of gas bubbles in the aria of a heat source is, from a physical point of view, quite interesting problem that leads to important conclusions for practical applications. The peculiarity of the process under consideration is that the surface tension of the bubble changes in an alternating temperature field, which, in turn, leads to the appearance of a flow in the boundary layer of the liquid. In the world scientific literature, the discovery and description of the effect of gas bubble migration in the direction of the temperature gradient is usually associated with the experimental work of Yang, Goldstein and Block (1959). Without diminishing its significance, we note that the effect was first predicted in the theoretical work of Fedosov (1956) as a result of solving the problem of the onset of a microflow of a liquid near plane and spherical interphase boundaries in the presence of a temperature gradient. In both works, a significant factor in explaining the described phenomenon was the dependence of surface tension on temperature. After some time, after which it was realized the need to take into account the migration of not only bubbles, but also droplets, in inhomogeneous temperature fields in space technologies, biomedical and other applications, there was a significant number of publications on this subject, and this phenomenon was called thermocapillary migration. This review is devoted to the analysis of the main, in the opinion of the authors of the article, results of experimental, theoretical and applied research to establish the mechanism of migration bubbles and drops in temperature gradient fields. In most works, it is assumed that there is no dependence of the physical properties of a liquid, except for surface tension, on temperature. There are only a few studies where the influence of the temperature dependence of the viscosity coefficient was considered, which gives a new impetus to the continuation of research and the development of the theory of the effect, taking into account the thermorheological properties of working media.

肠道气泡堆积对银鲳四种组织代谢酶活力的影响

肠道气泡堆积对银鲳四种组织代谢酶活力的影响

Vertical electropolishing for 1.3 GHz single- and nine-cell superconducting niobium cavities: A parametric optimization and rf performance

Electropolishing (EP) is a standard process for the treatment of the interior surface of niobium (Nb) superconducting radio-frequency (SRF) cavities used in particle accelerators. We previously conducted a study on vertical electropolishing (VEP), in which the cavity was set vertically during EP of a 1.3 GHz Nb single-cell cavity. In that study, we showed that the major cause of asymmetric removal in VEP is the accumulation of hydrogen gas bubbles, generated during the EP process, on the upper half cell of the cavity. Three types of unique rotating cathodes were tested with the aim to resolve the issues of asymmetric removal and rough surface. Appropriate cathode design and parameters reduced the asymmetric removal in the cell and yielded a smooth surface of the cavity. In this study, we have performed an extensive investigation on VEP of both single- and nine-cell Nb 1.3 GHz cavities with a modified cathode. The VEP parameters with single- and nine-cell coupon cavities were investigated, which facilitate an in situ study of the coupon currents at various positions of the cavities and observation from the viewports located near the iris and equator positions of the cavities. The modified cathode and optimized VEP process for the single-cell cavity yielded uniform removal in the cavity cell and a smooth surface of the interior of the cavity. A novel acid flow method that allows the separation of the acid flow in the cavity and cathode housing was employed in the nine-cell cavity to efficiently remove the gas bubbles from the cavity. The optimized acid flow rates in the cavity and cathode housing, along with other adequate parameters including temperature, cathode rotation speed, and applied voltage, made the surface smooth and significantly reduced the removal nonuniformity in the nine-cell cavity. The single- and nine-cell cavities after an average removal of 46 and $130\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$, respectively, were tested in a vertical cryostat. The single- and nine-cell cavities achieved $31\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ at a ${Q}_{0}$ value of $9\ifmmode\times\else\texttimes\fi{}{10}^{9}$ and $28.3\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ at a ${Q}_{0}$ value of $6.7\ifmmode\times\else\texttimes\fi{}{10}^{9}$, respectively, in the rf tests at the temperature of 2 K. The achieved SRF performances were as good as the baseline performances achieved after the horizontal electropolishing process of the same cavities.

2180 Why Is This Hemoperitoneum Orange? A Late Diagnosed Isolated Rupture of the Gallbladder Secondary to Blunt Abdominal Trauma

INTRODUCTION: The gallbladder is protected from blunt trauma by its unique anatomic position inferior to the liver and behind the rib cage. Biliary tree injuries are rare, occurring in approximately 2% of cases of blunt trauma. Isolated gallbladder injury is even rarer and the exact incidence is unknown. CASE DESCRIPTION/METHODS: 48 year old male with a history of alcohol abuse who was brought to the Emergency Department with right upper quadrant pain after falling over a fan. Labs showed stable chronic macrocytic anemia and elevated liver function tests. CT revealed ascitic fluid with suspected hemoperitoneum. Surgery managed the patient conservatively in light of stable serial hemoglobin values. Over the next 4 days, the patient developed shock with multi-organ failure. Primary team presumed deteriorating clinical status was related to alcoholic hepatitis and acute on chronic liver failure. Gastroenterology was then consulted and we recommended urgent diagnostic paracentesis. When smeared, the fluid was dark orange in color. A Medicine resident called the GI fellow and asked “why is this hemoperitoneum orange?” Ascitic bilirubin was 25 mg/dL. Surgery believed it was due to hemolysis of the hemoperitoneum. We transferred the patient for urgent ERCP that revealed external accumulation of contrast and bubbles in proximity to the gallbladder. A common bile duct stent was placed. Patient was taken for exploratory laparoscopy where a 5 cm defect on the anterior wall of gallbladder was noted and cholecystectomy was performed. Postoperative course was complicated by a 9 × 7 cm intra abdominal abscess. The collection was not amenable to Interventional Radiology drainage due to its proximity to the spleen. The patient underwent successful endoscopic cystogastrostomy with placement of a lumen apposing metal stent. DISCUSSION: Isolated gallbladder injury remains challenging to diagnose both clinically and radiologically. When suspected, percutaneous drainage is indicated to establish diagnosis even if radiological investigations are unrevealing. There is a high risk of morbidity and mortality secondary to a missed or delayed diagnosis. For patients in whom diagnosis is delayed, abdominal sepsis secondary to non-sterile biliary peritonitis can complicate the postoperative course. ERCP can be performed prior to surgery to reduce the pressure gradient between the biliary system and the duodenum allowing bile to drain preferentially into the duodenum.

Quench and Recovery Characteristics of Solenoid and Pancake SFCLs Under DC Impact Current

With the rapid development of the voltage source converter-based high voltage direct current (VSC-HVdc) power systems, as one of the methods for the suppression and interruption of short circuit current, resistive type dc superconducting fault current limiter (SFCL) is getting more and more attention. As SFCL will quench during the current limiting process, it is necessary to complete the quench and recovery process before the automatic reclosing of VSC-HVdc power systems. In this article, simulation and experimental analysis on SFCL are carried out. The superconducting tape used in the SFCL is the AMSC 8602 YBCO superconducting tape. It is concluded that the simulation results obtained by thermal conduction model using lumped parameter method are basically consistent with experimental results. With the increase of dc impact current and dc impact duration, recovery time of SFCL increases. Recovery time of the solenoid SFCL and the pancake SFCL under different placement modes differs, which is related to the heat dissipation space and the accumulation of bubbles.

Laser formation of luminescence bubble microstructures in polymer films

The results of laser-induced formation of luminescent structures on the surface of poly-2.2’-n-oxydiphenylene-5.5’-bis-benzimidazole films, obtained by the coating method from a formic acid solution, are presented. The structures are formed using cw 405-nm laser radiation with intensities of 102 – 104 W cm–2. It is shown (using methods of optical, atomic-force, and electron microscopy) that the structures formed on the surface are microbubble foam-like aggregations. Their formation is modelled as a sequence of the following processes: release of formic acid molecules, their condensation on matrix defects in the surface layer, and explosive boiling as a result of heating this layer of polymer film by the laser beam. The luminescence of these structures is due to the weakening of the concentration quenching from closely spaced luminescence centres in benzimidazole cycles during their emergence to the surface and the increase in the distance between them due to the extension on bubble aggregates on the surface.

Effect of Microscopic Oxygen Bubbles on Measured OER Catalyst Stability - a Comparative Study between RDE and MEA Measurements

Fast screening of OER catalysts for their intrinsic activity and stability is pivotal for the development of PEM electrolyzers.1 With respect to OER activity, catalyst screening is very well-established using different measurement techniques such as rotating disk electrode (RDE), flow-channel methods, or full cell measurements in an electrolyzer, where comparable activities are obtained. On the other hand, accelerated stability testing of OER catalysts has been reported to result in different stability lifetimes based on the testing method. For example, stability tests using the RDE technique result in magnificently shorter catalyst lifetimes than those using an electrolyzer.2 We have recently discovered that the use of an RDE-based galvanostatic test is not reliable to investigate the OER catalyst stability as the “apparent” catalyst degradation associated with this test is mostly due to a measurement artefact.3 During the OER galvanostatic test, oxygen gas bubbles form and accumulate in the pores of the catalyst layer, shielding the active surface area of the catalyst, therefore resulting in an increasing potential, mistakenly interpreted in the literature as catalyst degradation.4, 5 In this contribution, we present a comprehensive study in which we demonstrate how the accumulation of microscopic oxygen bubbles in the pores of the electrocatalyst layer during the OER results in an artefact that falsifies the estimated catalyst lifetime. We will show that this artefact exists in all RDE-based stability tests including galvanostatic, potentiostatic, and potential cycling techniques. Furthermore, we will show that the same artefact also exists during the stability test carried out using a membrane electrode assembly (MEA) in an electrolyzer, but to a much lesser extent compared to that associated with the RDE technique. We will also discuss how to mitigate this accumulation of gas bubbles in an MEA, and discuss possible protocols that enable the OER catalyst stability testing using RDE-based techniques. References L. Wang, F. Song, G. Ozouf, D. Geiger, T. Morawietz, M. Handl, P. Gazdzicki, C. Beauger, U. Kaiser, R. Hiesgen, A. S. Gago and K. A. Friedrich, J. Mater. Chem. A, 5(7), 3172–3178 (2017).S. Cherevko, Current Opinion in Electrochemistry, 8, 118–125 (2018).Hany A. El-Sayed, Alexandra Weiß, Lorenz F. Olbrich, Garin P. Putro, and Hubert A. Gasteiger, Journal of the Electrochemical Society, 166(8), F1-F7 (2019).H.-S. Oh, H. N. Nong, T. Reier, M. Gliech and P. Strasser, Chem. Sci., 6(6), 3321–3328 (2015).H.-S. Oh, H. N. Nong, T. Reier, A. Bergmann, M. Gliech, J. Ferreira de Araújo, E. Willinger, R. Schlögl, D. Teschner and P. Strasser, J. Am. Chem. Soc., 138(38), 12552–12563 (2016).

Electrolyte effects on recirculating dense bubbly flow: An experimental study using X‐ray imaging

AbstractIn this work, the effect of an electrolyte (up to 2 M of NaCl dissolved in water) on a homogeneous dense bubbly flow, in an airlift bubble column, is studied using nonintrusive techniques. X‐ray and high‐speed imaging are used to investigate the bubble size distribution, the local and the global gas‐fraction profiles. The major effect of the electrolyte is the bubble size distribution at the fine‐pore sparger, which is a consequence of the bubble coalescence inhibition promoted by the electrolyte. The bubble plume widening, the increase in overall gas fraction, and the onset of bubble recirculation in the column can all be explained by the bubble size reduction at the fine‐pore spargers. As a result of the bubble size reduction, the overall role of the electrolyte is in a reduction of the driving force for the liquid recirculation. Furthermore, an accumulation of the small bubbles causes a layer of foam at the free surface, which is dynamic in nature and induces additional bubble recirculation.

Can Stock Exchange Front-Line Supervision Identify Capital Market Risks? Evidence from the Annual Report Inquiry Letter

The corporate earnings management behavior will reduce the efficiency of capital market pricing, resulting in the accumulation of bubbles”, which is an important factor influencing risk hazards. In recent years, strengthening the front-line supervision of the exchange is an important action for China’s capital market to fill shortcomings. Therefore, it is of great significance to explore whether the front-line supervision of the exchange can identify the corporate earnings management behavior and to verify its active prevention and mitigation of risks. Based on the evidence of the annual report inquiry letter, this study uses Heckman’s two-stage approach to further explore whether the exchange has the whistleblower” risk screening ability on listed companies’ earnings management behavior. The results of the study show that: First, the higher the corporate accrued earnings management level is, the higher the probability of acceptance of the inquiry letter is, and in the sample of companies receiving the annual report inquiry letter, the higher the higher the accuracy of the inquiry letter is, which shows that the inquiry letter has a precise recognition function. Second, the cross-section grouping finds that the inquiry letter identifies more obviously in non-state-owned companies, Shenzhen Stock Exchange listed companies, and the media’s earnings management with high degree of concern and good legal environment. Third, the scalability test finds that the inquiry letter also has a screening effect on the relatively hidden real earnings management, and the inquiry letter mainly plays the role of reducing market information asymmetry by reducing companies’ future accounting performance for positive earnings management. This paper has the following contributions: First, the existing domestic literature mainly explores the economic consequences of the inquiry letter from the aspects of market reaction, audit quality, stock price crash risk and earnings management, but has not yet begun to pay attention to the influencing factors of the inquiry letter. Different from Chen, et al. （2019）, whether the inquiry letter can reduce the future earnings management behavior from the perspective of economic consequences, this paper mainly studies whether the current corporate earnings management can trigger the identification and supervision of the exchange annual inquiry letter from the perspective of influencing factors. The risk identification function of the inspection inquiry letter is precisely the important premise of the exchange’s governance role. It enriches and supplements the research on the effectiveness of the front-line supervision of the exchange by Chen, et al. （2019）, and also expands the study perspective of the domestic inquiry letter to a certain extent. According to the literature that the author has mastered, the existing research on the influencing factors of the inquiry letter abroad is mainly based on profitability, audit quality, corporate governance, tax evasion, political connections, etc. However, it has not yet paid attention to whether the corporate earnings management behavior can be accurately identified by the inquiry letter, which enriches the research on the influencing factors of the inquiry letter to a certain extent. Second, the existing literature mainly focuses on the impact of earnings management from the perspective of banks, firms and auditors, but lacks the perspective of public law enforcement to explore the economic consequences of earnings management. As a front-line of supervision, whether the exchange is sensitive to earnings management is of great significance to prevent the occurrence of risks. Third, different from the SEC comment letter in US, the main body of the Chinese inquiry letter is mainly a lower-level exchange. Exploring the effectiveness of the inquiry letter with Chinese characteristics can complement the literature in this field. It is also a test of the effect of the deepening the reform of the regulatory system” of the 19th National Congress and the reform of the information disclosure through the train policy in 2013.

Effects of helium irradiation dose and temperature on the damage evolution of Ti3SiC2 ceramic**Project supported by the President Foundation of the China Academy of Engineering Physics (Grant No. YZJJLX2018003) and the National Natural Science Foundation of China (Grant No. 21601168).

The effects of 400 keV helium ion irradiation dose and temperature on the microstructure of the Ti3SiC2 ceramic were systematically investigated by grazing incidence x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The helium irradiation experiments were performed at both room temperature (RT) and 500 °C with a fluence up to 2.0 ×1017 He+/cm2 that resulted in a maximum damage of 9.6 displacements per atom. Our results demonstrate that He irradiations produce a large number of nanometer defects in Ti3SiC2 lattice and then cause the dissociation of Ti3SiC2 to TiC nano-grains with the increasing He fluence. Irradiation induced cell volume swelling of Ti3SiC2 at RT is slightly higher than that at 500 °C, suggesting that Ti3SiC2 is more suitable for use in a high temperature environment. The temperature dependence of cell parameter evolution and the aggregation of He bubbles in Ti3SiC2 are different from those in Ti3AlC2. The formation of defects and He bubbles at the projected depth would induce the degradation of mechanical performance.

Hollow fiber membrane integrity warning device based on laser extinction particles detection technology

The breakage of hollow fiber membrane modules for the water treatment will re-pollute water and even compromise public health. In this study, an on-line warning and detection device based on the principle of laser extinction technology is put forward. The different particles such as solid particles and micro-bubbles in the permeate can be used as the tracer. The results indicated that the constant reference voltage Er constant at 2.3553 ± 0.0025 V when the membrane module was integrated; Once there is a breakage in the membrane module, the solid particles in the permeate will lead to an overall drop in voltage Eu, and the micro-bubbles will form a voltage pulse Ep as a special warning. The detection limit of turbidity is 0.12 NTU and the detection limit of the micro-bubble is about 30 μm with bubble aggregation bend tubes. The correlation coefficient of the voltage and the turbidity in permeate was 0.9722, and micro-bubbles detected by the device have the same trend with the particle counter. As a result of these findings, the extinction method does not need to add tracer particles, no background effect, and can detect the permeate on-line with the potential to install in every module. It may potentially prove to be a viable treatment option for the warning of hollow fiber membrane integrity.

Experimental research on subcooled flow boiling heat transfer performance and associated bubble characteristics under pulsating flow

An experimental research was conducted to study the effects of non-reversing pulsating flow on subcooled boiling heat transfer performance on a chip using FC-72 in a horizontal rectangular narrow channel with a hydraulic diameter of 8.57 mm. The associated bubble characteristics were also analyzed. In the experiment, the pulsating period varied from 3 s to 20 s with the pulsating amplitude changing from 20% to 50% for the inlet liquid subcooling of 35 K. The result indicates that time-average boiling curves under pulsating flow overlapped with that under steady flow, and the heat transfer coefficient was not affected by flow pulsation. The critical heat flux (CHF) decreased compared with that under time-average steady flow, and the decrease would be further aggravated with the increases of the pulsating amplitude or the decrease of the pulsating period. The CHF under pulsating flow was limited by the lowest flow rate. Bubble behavior changed periodically with the flow rate, and bubble accumulation effect under pulsating flow was found. There was no slide process during bubble growth, and the bubbles near the CHF tended to be bigger and more round-like with no obvious deformation. This phenomenon was caused by the virtual mass force acting on the bubble due to fluid acceleration.

Numerical investigation on the CHF model and prediction for the external cooling channel of lower head

External cooling of the lower head can reduce the possibility of the damage to the pressure vessel in serious accidents. However, when the core melt heats the lower head with a high heat flux subcooled boiling under natural circulation may cause bubble accumulation, which results in the deterioration of heat transfer or even radioactive leakage. This phenomenon is essentially the critical heat flux (CHF) on a curved surface with a downward heating boundary. The estimation of this phenomenon is indispensable for reactor safety design.In this paper, improvement in the nucleation density model exhibits higher resulting calculation performance for CHF with new geometries or working conditions. The CHF values and CHF distribution along the ellipsoidal and spherical structures are obtained, and detailed comparison between these two structures is made. The characteristics of elliptical cooling channel prove completely different from those of spherical structure, which requires more experimental studies.

Periodic Trends in Two-Phase Flow Through a Vertical Minichannel: Wavelet and Multiscale Entropy Analyses Based on Digital Camera Data

Abstract By changing the air and water flow relative rates in the two-phase (air-water) flow through a minichannel, we observe aggregation and partitioning of air bubbles and slugs of different sizes. An air bubble arrangement, which show non-periodic and periodic patterns. The spatiotemporal behaviour was recorded by a digital camera. Multiscale entropy analysis is a method of measuring the time series complexity. The main aim of the paper was testing the possibility of implementation of multiscale entropy for two-phase flow patterns classification. For better understanding, the dynamics of the two-phase flow patterns inside the minichannel histograms and wavelet methods were also used. In particular, we found a clear distinction between bubbles and slugs formations in terms of multiscale entropy. On the other hand, the intermediate region was effected by appearance of both forms in non-periodic and periodic sequences. The preliminary results were confirmed by using histograms and wavelets.

Evidence for pore-filling gas hydrates in the sediments through morphology observation

To provide an evidence of natural gas hydrate occurrence state, a series of experiments on multiple growth and dissociation of 90.0% methane/10.0% propane hydrates at 1.3 MPa and 270.15 K were carried out in two sediments for morphology observation via a visible jacketed-reactor. The gas hydrate crystals were observed to form and grow on the surface of sediments at the initial growth. During the thermal decomposition, gas and liquid products had an unceasingly impact on the sediments, then gas/liquid–solid migration occurred, and a large number of cavitation appeared. In the later growth and dissociation experiments, the gas hydrate particles were in suspension or supporting states in the interstitial pore space between the sediment particles, indicating that the gas hydrate displayed a pore-filling characteristics. Through analyzing the distribution of gas hydrates and bubbles, it was found that the amount of gas hydrates distributed in the sediments was improved with multiple growth-dissociation cycle proceedings. Gas migration enhanced the sediment movement, which led to the appearance of the increasing quantity of gas bubbles in the sediments during cycles. Salts affected the growth of the gas hydrates and the migration of sediment grains, which also restricted the accumulation of gas bubbles in the sediments. According to the Raman analysis, the results showed that sII hydrates were formed for CH4 and C3H8 gas mixtures in different sediments and solutions with hydration number of 5.84–6.53. The Salt restricted the access of gas into the hydrate cages.

Analysis of the effect of surface wettability on hydrogen evolution reaction in water electrolysis using micro-patterned electrodes

The hydrogen evolution reaction (HER) was investigated using Ni catalytic electrodes with micro-patterned surfaces. The present aim was to correlate HER efficiency with the surface wettability of Ni cathodes produced with different micropatterns. Regular Ni microdot arrays, 5–10 μm in diameter, 5–10 μm in pitch were fabricated on a 7 mm diameter Cu substrate and tested in alkaline water electrolysis (AWE) experiments. Using electrodes of this design, it may be possible to relate the electrochemical reaction kinetics to the electrolyte wettability localized to the microdot surface area. The surface microstructures of the electrode considerably influenced the reaction efficiency of the HER during alkaline water electrolysis at −20 mA cm−2. Furthermore, in situ video observations of the electrode surface during the HER revealed that the bubble size increased when the surface wettability of the electrodes was decreased. That is, the surface texture (micro-patterns) affected the HER efficiency by influencing bubble evolution and aggregation behavior. This observation may aid in the design of highly efficient HER catalytic electrodes.

New constraints on mantle carbon from Mid-Atlantic Ridge popping rocks

Despite the influence of mantle carbon on melt formation and migration, global volatile budgets, and volcanic eruption styles, the carbon concentration in Earth's upper mantle remains highly debated, with estimates varying by more than an order of magnitude. The relationship between carbon and incompatible trace element (e.g., Nb, Ba) concentrations in rare, undegassed mid-ocean ridge basalts and melt inclusions provide primary constraints on upper mantle carbon content. Here we investigate whether the most volatile rich mid-ocean ridge basalts, termed ‘popping rocks’, represent undegassed magmas from the upper mantle and provide insight into upper mantle carbon inventory. We show that fourteen new popping rocks, collected in situ from the Mid-Atlantic Ridge rift valley near 14°N, contain highly variable CO2/Nb and CO2/Ba ratios despite similar mantle sources and extents of melting. We revise the original model for popping rock formation using seafloor observations, high-resolution bathymetry, vesicle size distributions, major and trace element geochemistry, and noble gas geochemistry. Highly variable volatile concentrations despite relatively homogeneous trace element ratios and low 4He/40Ar⁎ suggest that bubble accumulation affected these popping rocks. These results provide evidence for heterogeneity in the CO2/Ba ratio of the depleted mantle and indicate that mantle carbon concentrations are lower and less heterogeneous than previously estimated, which influences models for mantle melting and CO2 flux at mid-ocean ridges.