Leakage Measurements Research Articles

A critical review on the role of leakages in the facemask protection against SARS-CoV-2 infection with consideration of vaccination and virus variants.

The protection provided by facemasks has been extensively investigated since the beginning of the SARS-CoV-2 outbreak, focusing mostly on the filtration efficiency of filter media for filtering face pieces (FFP), surgical masks, and cloth masks. However, faceseal leakage is a major contributor to the number of potentially infectious airborne droplets entering the respiratory system of a susceptible individual. The identification of leaking spots and the quantification of leaking flows are crucial to estimate the protection provided by facemasks. This study presents a critical review on the measurement and calculation of facemask leakages and a quantitative analysis of their role in the risk of SARS-CoV-2 infection. It shows that the pairing between the mask dimensions and the wearer's face is essential to improve protection efficiency, especially for FFP2 masks, and summarizes the most common leaking spots at the interface between the mask and the wearer's face. Leakage is a crucial factor in the calculation of the protection provided by facemasks and outweighs the filtration performances. The fit factors measured among mask users were summarized for different types of face protection. The reviewed data were integrated into a computational model to compare the mitigation impact of facemasks with vaccination with consideration of new variants of SARS-CoV-2. Combining a high adoption rate of facemasks and a high vaccination rate is crucial to efficiently control the spread of highly infectious variants.

Antifungal potential of isoespintanol extracted from Oxandra xylopioides diels (Annonaceae) against intrahospital isolations of Candida SPP

The aim of this study was to evaluate the antifungal activity of isoespintanol (ISO) extracted from Oxandra xylopioides Diels (Annonaceae) against clinical isolates of Candida spp. Isoespintanol was obtained from the petroleum benzine extract of the leaves and was identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS). For antifungal activity experiments, the broth microdilution method was used. The results show an inhibitory effect against Candida spp., with minimum inhibitory concentration (MIC) values between 450.4–503.3 μg/mL. Furthermore, the inhibitory effect of ISO against fungal biofilms is highlighted, even in some cases, greater than the effect shown by amphotericin B (AFB) and in others, where AFB showed no effect. Assays with fluorescent staining with acridine orange (AO) and ethidium bromide (EB), transmission electron microscopy (TEM), Evans blue, measurement of extracellular pH and leakage of intracellular material, evidenced damage at the level of fungal membranes and general cell damage, when cells were exposed to ISO, compared to untreated cells. The results of this research, serve as the basis for future studies in the establishment of the mechanisms of antifungal action of ISO, which could serve as an adjunct in the treatment of infections by these yeasts.

Wall thickness image construction in wellbore casings using data-driven inversion of magnetic flux leakage

We describe the response of magnetic flux leakage measurements obtained in wellbore casings and detail an analytical approach for inverting the data to construct a 3D image of metal loss for the general case in which the magnetic permeability of the casing is unknown. This approach contrasts with current practice which assumes a defect shape and attempts to deduce metal loss from one or more response metrics matched to a library of defects generated under laboratory conditions for that shape. The traditional approach breaks down where defects do not conform to the assumed shape and when the properties of the laboratory casing are not the same as the properties of the installed casing. Moreover, there is no direct way to know whether magnetic flux in the casing is at saturation level; thus, the measurement could be operating in a nonlinear part of the magnetization curve whose shape also is unknown. The new method makes no assumptions about defect shape and approximates the relevant part of the magnetization curve within an inversion process that transforms the flux scan into a metal loss scan showing the shape and depth of metal loss. The approach is validated using data from simulations, laboratory tests, and field operations. Unlike images of flux distribution, thickness profiles reconstructed from the results of the inversion reflect the actual distribution of metal loss to a useful level of accuracy and thereby enable the casing’s mechanical integrity to be assessed with greater confidence.

Blood-brain barrier leakage years after pre-eclampsia: dynamic contrast-enhanced 7-Tesla MRI study.

Pre-eclampsia is a hypertensive complication of pregnancy that is associated with an increased risk of long-term cardiovascular and cerebrovascular disorders. Although the underlying mechanism of persistent susceptibility to cerebral complications after pre-eclampsia remains largely unclear, impaired blood-brain barrier (BBB) integrity has been suggested to precede several cerebrovascular diseases. In this study, we aimed to investigate the integrity of the BBB years after pre-eclampsia. This was an observational study of premenopausal formerly pre-eclamptic women and controls with a history of normotensive pregnancy who underwent cerebral magnetic resonance imaging (MRI) at ultra-high field (7Tesla) to assess the integrity of the BBB. Permeability of the BBB was determined by assessing leakage rate and fractional leakage volume of the contrast agent gadobutrol using dynamic contrast-enhanced MRI. BBB leakage measures were determined for the whole brain and lobar white and gray matter. Multivariable analyses were performed, and odds ratios were calculated to compare women with and those without a history of pre-eclampsia, adjusting for potential confounding effects of age, hypertension status at MRI and Fazekas score. Twenty-two formerly pre-eclamptic women (mean age, 37.8 ± 5.4 years) and 13 control women with a history of normotensive pregnancy (mean age, 40.8 ± 5.5 years) were included in the study. The time since the index pregnancy was 6.6 ± 3.2 years in the pre-eclamptic group and 9.0 ± 3.7 years in controls. The leakage rate and fractional leakage volume were significantly higher in formerly pre-eclamptic women than in controls in the global white (P = 0.001) and gray (P = 0.02) matter. Regionally, the frontal (P = 0.04) and parietal (P = 0.009) cortical gray matter, and the frontal (P = 0.001), temporal (P < 0.05) and occipital (P = 0.007) white matter showed higher leakage rates in formerly pre-eclamptic women. The odds of a high leakage rate after pre-eclampsia were generally higher in white-matter regions than in gray-matter regions. This observational study demonstrates global impairment of the BBB years after a pre-eclamptic pregnancy, which could be an early marker of long-term cerebrovascular disorders. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

In vivo evaluation of a lipopolysaccharide-induced ear vascular leakage model in mice using photoacoustic microscopy.

Sepsis is caused by dysregulated host inflammatory response to infection. During sepsis, early identification and monitoring of vascular leakage are pivotal for improved diagnosis, treatment, and prognosis. However, there is a lack of research on noninvasive observation of inflammation-related vascular leakage. Here, we investigate the use of photoacoustic microscopy (PAM) for in vivo visualization of lipopolysaccharide (LPS)-induced ear vascular leakage in mice using Evans blue (EB) as an indicator. A model combining needle pricking on the mouse ear, topical smearing of LPS on the mouse ear, and intravenous tail injection of EB is developed. Topical application of LPS is expected to induce local vascular leakage in skin. Inflammatory response is first validated by ex vivo histology and enzyme-linked immunosorbent assay. Then, local ear vascular leakage is confirmed by ex vivo measurement of swelling, thickening, and EB leakage. Finally, PAM for in vivo identification and evaluation of early vascular leakage using the model is demonstrated. For PAM, common excitation wavelength of 532 nm is used, and an algorithm is developed to extract quantitative metrics for EB leakage. The results show potential of PAM for noninvasive longitudinal monitoring of peripheral skin vascular leakage, which holds promise for clinical sepsis diagnosis and management.

Mechanism and preventive measures of slurry leakage at shield tail brushes under abnormal shutdown condition—A case study

Based on an underwater shield tunnel project, this study introduces the phenomenon of abnormal shutdown and the measures designed to mitigate problems in construction. On the strength of the analysis of the slurry leakage causes during re-tunneling, the mechanism of slurry leakage induced by jack retraction was studied, and treatment measures of leakage at shield tail brushes were elaborated upon. The results show that the sudden change of stratum leads to an abnormal shutdown, and a sharp increase in the slurry pressure at the shield cut location leads to the slurry penetrating the gap between the outer wall of the shield shell and the soil, increasing the risk of instantaneous breakdown at shield tail brushes. The radial displacement of the outer wall of the segments caused by retractions of three jacks and a single jack along the circumferential direction distinctly shows three regions and four regions, respectively. The radial shrinkage of the outer wall of the segments at the jack retraction position decreases the tightness between the shield tail brushes and the outer wall of the segments. The expansion of the outer wall of the segments at the surrounding position, especially at the lower position, increases the slurry level to the radial shrinkage position of the segments, which increases the risk of slurry leakage. Furthermore, when the shield machine faces an abnormal shutdown, re-tunneling, and assembly of segments, the jack can be gradually retracted from top to bottom. The slurry leakage degree can be observed when retracting, and the corresponding measures can be taken for timely plugging. According to the leakage degree, it can be determined whether to replace the shield tail brushes to reduce the risk of large-scale leakage accidents.

Fracture Distribution Characteristics in Goaf and Prevention and Control of Spontaneous Combustion of Remained Coal under the Influence of Gob-Side Entry Retaining Roadway

Based on the ventilation characteristics of the gob-side entry retaining face, a mathematical model of spontaneous combustion in the gob-side entry retaining face is established. From the overburden caving of the goaf along the goaf retaining roadway, the development characteristics of rock strata and residual coal fissures in the goaf are summarized and analyzed. In addition, by using numerical simulation software, the effects of normal mining period, goaf retaining roadway as return air roadway, air leakage prevention, and nitrogen injection measures in goaf on spontaneous combustion in goaf are studied, and the distribution characteristics of flow field, oxygen concentration field and temperature field in goaf are obtained. The results show that the mining of the Geng 20 working face has a significant impact on the Geng 19 coal seam. The Geng 19 coal seam is in the range of fracture zone, and the fracture is well developed. Furthermore, the permeability coefficient of the Geng 19 coal seam increases sharply, air leakage in the goaf is increased along the goaf retaining roadway, and the range of oxygen concentration is enlarged, which results in a temperature rise in the goaf. Therefore, air leakage measures are proposed along the goaf to inject 900 m3/h of nitrogen into the goaf, which can prevent the spontaneous combustion of coal left over in the goaf. In addition, according to the characteristics of fracture development and numerical simulation of spontaneous combustion in goaf under the goaf retaining roadway, the hierarchical prevention, control, and fire extinguishing technology system of the goaf retaining roadway is constructed.

Isoflavaspidic Acid PB Extracted from Dryopteris fragrans (L.) Schott Inhibits Trichophyton rubrum Growth via Membrane Permeability Alternation and Ergosterol Biosynthesis Disruption.

Isoflavaspidic acid PB (PB), a phloroglucinol derivative extracted from aerial parts of Dryopteris fragrans (L.) Schott, had antifungal activity against several dermatophytes. This study was aimed at exploring the antifungal mechanism of PB against Trichophyton rubrum (T. rubrum). The effectiveness of PB in inhibiting T. rubrum growth was detected by time-kill kinetics study and fungal biomass determination. Studies on the mechanism of action were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), sorbitol and ergosterol assay, nucleotide leakage measurement, and UPLC-based test and enzyme-linked immunosorbent assay. Fungicidal activity of PB was concentration- and time-dependent at 2 × MIC (MIC: 20 μg/mL) after 36 h. The total biomass of T. rubrum was reduced by 64.17%, 77.65%, and 84.71% in the presence of PB at 0.5 × MIC, 1 × MIC, and 2 × MIC, respectively. SEM analysis showed that PB changed mycelial morphology, such as shrinking, twisting, collapsing, and even flattening. TEM images of treated cells exhibited abnormal distributions of polysaccharide particles, plasmolysis, and cytoplasmic content degradation accompanied by plasmalemma disruption. There were no changes in the MIC of PB in the presence of sorbitol. However, the MIC values of PB were increased by 4-fold with exogenous ergosterol. At 4 h and 8 h, PB increased nucleotide leakage. Besides, ergosterol content in T. rubrum membrane treated with PB at 0.5 × MIC, 1 × MIC, and 2 × MIC was decreased by 9.58%, 15.31%, and 76.24%, respectively. There was a dose-dependent decrease in the squalene epoxidase (SE) activity. And the reduction in the sterol 14α-demethylase P450 (CYP51) activity was achieved after PB treatments at 1 × MIC and 2 × MIC. These results suggest that PB displays nonspecific action on the cell wall. The membrane damaging effects of PB were attributed to binding with ergosterol to increase membrane permeability and interfering ergosterol biosynthesis involved with the reduction of SE and CYP51 activities. Further study is needed to develop PB as a natural antifungal candidate for clinical use.

A Comparison of Water Imbibition and Controlled Deterioration in Five Orthodox Species

Orthodox seeds deteriorate even when stored in the best of conditions; hence, it is very important to monitor germination in stored seeds. To assess orthodox seed deterioration, a germination test is usually employed. This study assessed and compared seed deterioration in five orthodox species using electrolyte leakage and Fourier transform infrared spectroscopy (FTIR). The study also compared water imbibition by the test orthodox seeds. To achieve this, the seeds from three wild (Bolusanthus speciosus; Combretum erythrophyllum; Erythrina caffra) and two agricultural (Pisum sativum and Cucurbita pepo) species were imbibed between 20 layers of single-ply paper towel. The other set was subjected to controlled deterioration at 40 °C and 100% relative humidity for 32 d, with samples taken for germination and electrolyte leakage measurement at 4 d intervals. FTIR measurements were performed at 0, 20, and 32 d of controlled deterioration. The results indicated that there were some significant interspecies differences in the imbibition times and seed water contents but these were not large. In all species, uptake of water was complete between about 15 and 25 h. The wild species showed higher sensitivity to controlled deterioration. Complete loss of germinability occurred much earlier in the wild species (20 d in B. speciosus and E. caffra, and 16 d in Co. erythrophyllum) compared with 36 d for the agricultural species P. sativum and Cu. pepo. There was a negative correlation between electrolyte leakage and seed germination in all wild and agricultural species. A strong positive correlation was observed between the time of controlled deterioration, electrolyte leakage, and FTIR transmission in all the species. While controlled deterioration may help in decisions relating to the storage of orthodox seeds, the water imbibition results from this study will help to set the priming time of the species. The study reaffirms electrolyte leakage as an indicator of seed viability in P. sativum and Cu. pepo; it also recommends the use of electrolyte leakage as an indicator of seed deterioration in B. speciosus, Co. erythrophyllum, and E. caffra. The study also recommends FTIR as a tool for monitoring the germination of stored seeds of all the test species.

Risk factors for colorectal anastomotic leakage and preventive measures: a retrospective cohort study

Background. Colorectal anastomotic leakage (AL) has always been one of major challenges in rectal surgery. Objective: to perform multivariate analysis of risk factors for AL. Materials and methods. In this retrospective cohort study, we analyzed patients that had undergone resection of the rectum with anastomosis formation between 2013 and 2020. We included patients with favorable prognostic factors (tumor located >5 cm above the anal verge, no history of chemoradiotherapy). We performed multivariate analysis using logistic regression to assess risk factors for AL. Results. The use of more than 3 linear stapler firings to suture the rectum significantly increased the risk of AL (risk ratio 3.035; 95 % confidence interval 1.473–6.252; p = 0.003). The univariate analysis demonstrated that reinforcement of the anastomosis was significantly associated with an increased risk of AL (risk ratio 2.35; 95 % confidence interval 1.112–5.762; p = 0.027); however, this association failed to reach statistical significance (risk ratio 1,520; p = 0,066). Pelvic peritoneum suturing had no impact on the AL incidence, but in case of its development, pelvic peritoneum reconstruction prevented peritonitis ( p = 0.002). Conclusion. The number of stapler firings >3 used to suture the rectum, as well as reinforcement of the anastomosis tended to increase the risk of AL; however, these findings did not reach the level of statistical significance. Pelvic peritoneum reconstruction did not affect the incidence of AL, but significantly reduced the risk of peritonitis.

Cement augmentation in spinal surgery

Bone cement has been used in spinal surgery for as long as 50years. In contemporary spinal surgery, cement augmentation of fractured osteoporotic vertebrae in the form of vertebroplasty/kyphoplasty as well as cement augmentation of pedicle screws in instrumented procedures of any etiology are established as standard procedures. Both procedures are very effective, although the benefits of vertebroplasty/kyphoplasty procedures have been controversially discussed in the past. Overall, complications rarely occur. The most relevant complication is cement leakage, which is asymptomatic in the majority of cases but in the worst case might lead to neurological deficits, embolic events and even circulatory collapse. Prevention of cement leakage is therefore crucial. Risk factors for cement leakage and preventive measures are presented in acomprehensive review based on the available literature.

Practical Challenges and Opportunities for Marine Plastic Litter Reduction in Manila: A Structural Equation Modeling

Land-based plastic pollution has increased to the level of an epidemic due to improper plastic waste management, attributed to plastic waste flux into the marine environment. The extant marine plastic litter (MPL) literature focuses primarily on the monitoring and assessment of the problem, but it fails to acknowledge the link between the challenges and opportunities for MPL reduction. The study aimed to examine the practical challenges and opportunities influencing the reduction of marine plastic litter in Manila in the Philippines. Data collected through an online survey from 426 barangays were analyzed using structural equation modeling (SEM) and were then validated using interviews and focused group discussions. Good internal consistency (0.917) and convergent and discriminant validity were achieved. The empirical study has established structural model fit measures of RMSEA (0.021), SRMR (0.015), CFI (0.999), and TLI (0.994), with a good parsimonious fit of the chi-square/degrees of freedom ratio of 1.190. The findings revealed that environmental governance regarding waste management policies and guidelines, COVID-19 regulations for waste management, community participation, and socio-economic activities have positively affected marine plastic litter leakage and solution measures. Environmental governance significantly and partially mediates the effects of, e.g., COVID-19-related waste and socio-economic activities on MPL leakage. However, there is no relationship between the waste management infrastructure and environmental governance. The findings shed light on how to enhance environmental governance to reduce marine plastic litter and address Manila’s practical challenges.

Optimal Pressure Management in Water Distribution Systems: Efficiency Indexes for Volumetric Cost Performance, Consumption and Linear Leakage Measurements

Water is a finite resource and should be given the attention it deserves to reduce its depletion through leakages in pipe systems. The authors implemented pressure management strategies linked to fixed and variable discharge (FAVAD), the burst and background estimate (BABE), and orifice principle methodologies to analyze a two-phased comparative method for applying optimal pressure management and its efficiency indexes in measuring volumetric cost performance, consumption, leakage flowrate, linear leakage reduction, infrastructural leakage and leakage cost indices. Using time-modulated smart control pressure reducing valve (PRV) simulation processes, the authors selected Alexandra Township in Johannesburg, South Africa as a case study. The results showed a reduction in head pressure, a reduction in the system input volume (SIV) from 26,272,579 m3 to 21,915,943 m3 and a reduction in minimum night flow (MNF) from 14.01% to 12.50%. The annual estimated nodal system output (NSO) was reduced from 14,774.62 m3 to 12,787.85 m3. The monthly average linear system repairs were reduced from 246 to 177, while the efficiency index percentages of leakage frequency/km/pressure were reduced from 8.31% to 5.98%. At a unit cost of $3.18/m3, the cost of leakages declined from $4,009,315.54 to $2,862,053.10 per month, while average household consumption (AMC) reduced from 36.33 m3 to 24.56 m3. Finally, the linear reduction value R2 for the percentage of the total leakage flowrate (TLFR)/SIV declined from 0.58 to 0.5, whereas the infrastructure leakage ratio (ILI) increased from 4 to 4.3. The results fully demonstrated that optimal pressure management is an alternative way to simulate, estimate, quantify and understand where and how water is lost in a distribution system. The authors propose that the implementation of proactive leakage management and domestic background leakage repair could further assist in reducing the frequency and cost of water leakages.

High attack rate in a Tong Lau house outbreak of COVID-19 with subdivided units in Hong Kong.

Poor housing conditions are known to be associated with infectious diseases such as high Coronavirus disease 2019 (COVID-19) incidences. Transmission causes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in poor housing conditions can be complex. An understanding of the exact mechanism of transmission can help to pinpoint contributing environmental issues. Here, we investigated a Hong Kong COVID-19 outbreak in early 2021 in four traditional Tong Lau houses with subdivided units. There are more than 80 subdivided units of less than 20 m2 floor area each on average. With a total of 34 confirmed COVID-19 cases, the outbreak had an attack rate of 25.4%, being one of the highest attack rates observed in Hong Kong, and ranked among the highest attack rates in reported outbreaks internationally. Tracer gas leakage and decay measurements were performed in the drainage system and in the subdivided units to determine the transport of infectious aerosols by the owner-modified sophisticated wastewater drainage pipe networks and the poor ventilation conditions in some subdivided units. The results show that the outbreak was probably due to multiple transmission routes, i.e. by the drainage pipe spread of stack aerosols, which is enhanced by poor ventilation in the subdivided units.

Physically Secure Wearable–Wearable Through-Body Interhuman Body Communication

Human body communication (HBC) has recently emerged as an alternative method to connect devices on and around the human body utilizing the electrical conductivity properties of the human body. HBC can be utilized to enable new interaction modalities between computing devices by enhancing the natural interaction of touch. It also provides the inherent benefit of security and energy-efficiency compared to a traditional wireless communication, such as Bluetooth, making it an attractive alternative. However, most state-of-the-art HBC demonstrations show communication between a wearable and an Earth ground–connected device, and there have been very few implementations of HBC systems demonstrating communication between two wearable devices. Also, most of the HBC implementations suffer from the problem of signal leakage out of the body which enables communication even without direct contact with the body. In this article, we present BodyWire which uses an electro-quasistatic HBC (EQS-HBC) technique to enable communication between two wearable devices and also confine the signal to a very close proximity to the body. We characterize the human body channel loss under different environment (office desk, laboratory, and outdoors), posture, and body location conditions to ascertain the effect of each of these on the overall channel loss. The measurement results show that the channel loss varies within a range of 15dB across all different posture, environmental conditions, and body location variation, illustrating the dynamic range of the signal available at the input of any receiver. Leakage measurements are also carried out from the devices to show the distance over which the signal is available away from the body to illustrate the security aspect of HBC and show its effect on the channel loss measurements. For the first time, a through-body interhuman channel loss characterization is presented. Finally, a demonstration of secure interhuman information exchange between two battery-operated wearable devices is shown through the BodyWire prototype, which shows the smallest form factor HBC demonstration according to the authors’ best knowledge.

Phytotoxicity of Silver Nanoparticles with Different Surface Properties on Monocots and Dicots Model Plants

The aim of the research was to evaluate the effect of three types of silver nanoparticles (AgNPs) with different physicochemical properties and silver ions delivered in the form of silver nitrate (AgNO3) at the concentration of 50 mg L−1 on germination and initial growth of monocots (common wheat, sorghum) and dicots (garden cress, white mustard). The AgNPs were prepared using trisodium citrate (TCSB-AgNPs), tannic acid (TA-AgNPs), and cysteamine hydrochloride (CHSB-AgNPs). They exhibited comparable shape, size distribution, and an average size equal to 15 ± 3 nm which was confirmed with the use of transmission electron microscopy. The electrokinetic characteristics revealed that CHSB-AgNPs have positive, whereas TCSB-AgNPs and TA-AgNPs negative surface charge. First, toxicity of the silver compounds was assessed using the Phytotestkit test. Next, after transferring seedlings to pots, shoot length, leaf surface, shoot dry mass, electrolyte leakage measurement, and photosystem II (PSII) efficiency were determined. AgNPs and silver ions delivered in the form of AgNO3 reduced root and shoots length of common wheat, sorghum, and garden cress; leaves surface of garden cress and white mustard; and shoots dry mass of white mustard. The positively charged CHSB-AgNPs and silver ions delivered in the form of AgNO3 showed the greatest inhibition effect. Moreover, silver ions and positively charged CHSB-AgNPs were more toxic to PSII of model plants than negatively charged TCSB-AgNPs and TA-AgNPs. AgNPs impact differed in the case of monocots and dicots, but the size of the changes was not significant, so it concerned individual parameters. The results revealed the interaction strength, which was generally similar in all tested plants, i.e., increasing negative effect in sequence TCSB-AgNPs < TA-AgNPs < silver ions delivered in the form of AgNO3 < CHSB-AgNPs.

Cause and mechanism analysis of cracking and leakage of water wall tube

In this paper, the cracking and leakage cause of the water wall tube was studied by means of macro morphology analysis, chemical composition analysis, microstructure detection, mechanical properties test and energy dispersive X-ray spectroscopy (EDS) analysis. The results indicated that the cracking of water wall reducer is mainly related to high temperature fatigue and sulfur corrosion. During operation, under the combined action of thermal expansion and contraction caused by frequent boiler load changes and axial alternating stress caused by pipe wall vibration, thermal fatigue cracks are gradually formed on the outer wall of the steel pipe toward the fire side. Under the combined action of the alternating stress and S corrosion, the cracks are gradually spread from outer to inner wall, and finally penetrate the tube wall, causing leakage. Finally, the corresponding preventive measures of water wall leakage are put forward to improve the safety and economy of power plant boiler.

Evaluating VEGF-Induced Vascular Leakage Using the Miles Assay.

Before the endothelial mitogenic activity of the Vascular Endothelial Growth Factor A (VEGF) was described, VEGF had already been identified for its ability to induce vascular leakage. VEGF-induced vascular leakage has been most frequently studied in vivo using the Miles assay, a simple yet invaluable technique that has allowed researchers to unravel the molecular mechanisms underpinning vascular leakage both for VEGF and other permeability inducing agents. In this protocol, a mouse is intravenously injected with Evans Blue dye before VEGF is administered locally via intradermal injection. VEGF promotes vascular leak of serum proteins in the dermis, enabling Evans Blue-labeled albumin extravasation from the circulation and subsequent accumulation in the skin. As the volume of dye extravasation is proportional to the degree of vascular leak, it can be quantified as a proxy measurement of VEGF-induced vascular leakage.

Research on the establishment of gas channeling barrier for preventing SCP caused by cyclic loading-unloading in shale gas horizontal wells

Sustained casing pressure (SCP) was an urgent problem to be solved during shale gas exploration and development. To cope with the issue of SCP, a method of establishing gas channeling barrier was proposed, and the location of the barrier was optimized, considering engineering and geological factors. A series of tests, containing uniaxial/triaxial compression tests and cyclic loading-unloading tests, were carried out to evaluate the accumulated plastic strain. Also, a full-scale cement sheath sealing integrity evaluation device was employed to verify the appearance of the micro-annulus. Computed tomography scan and nuclear magnetic resonance tests were performed to measure and analyze the distribution of microcracks and pores in the cement sheath after cyclic loading-unloadings. Numerical models of the wellbore assembly were established, which considered wellbore structures of different intervals of an actual deep shale gas well. Research findings indicated that after loading and unloading a certain number of times, the accumulation of plastic strain showed an increasing trend with the increase of the measured depth in the vertical section, but decreased with the rise of the measured depth in the horizontal section. The method of setting gas channeling barrier was proposed and could be used to avoid SCP by using the cement slurry with low elastic modulus, which could significantly reduce the cost of cementing operation. Many factors, including the non-uniform in-situ stress, wellbore structure, fracturing stage number, casing internal pressure, and formation mechanical properties were considered to establish the optimization method of barrier locations, and this method was verified by using the logging data of an actual well as well as the engineering and geological data. • An optimization method of establishing gas channeling barrier was proposed. • Loading-unloading of inner pressure leads to porosity increase of cement sheath. • First barrier should be established far away from the heel. Fig. 8 displays the gas leakage measurement results. As observed, gas leakage was detectable in the 22nd cycle at the injected gas pressure of 5 MPa. The gas channeling rate also increased as the injection pressure elevated. In order to observe which interface failed, the annulus was photographed, as presented in Fig. 9 . Obviously, micro-annulus appears at the inner surface of the cement sheath without internal cracks following repeated loading/unloading cycles. The obtained results show that the micro annulus mainly occurs in the inner interface of cement sheath.

Physiological Response of the Resurrection Fern Subjected to Environmental Stress as Shown by Plant Cell Membrane Integrity

Resurrection fern has a unique ability to maintain cell wall integrity when the plant cell is desiccated. It uses proteins such as late embryogenesis proteins and heat shock proteins to maintain their cellular functions. The purpose of this experiment is to determine the effects of environmental stressors on the physiological response of the resurrection fern (Pleopeltis polypodioides). The physiological response of resurrection fern plants was subjected to various temperatures (-50°C, 0°C, 25°C, and 50°C) for 7 days. Results indicated that there was a significant difference between hydrated and desiccated ferns based on the temperature. Additionally, electrolyte leakage measurements confirmed cell damage following exposure to temperature extremes of -50°C and 50°C.