ABSTRACT
Sealing faults are nearly impermeable barriers that can form boundaries between subsurface pore-pressure domains. In hydrocarbon systems, sealing faults commonly form part of a structural trap; they are thus important elements for future storage of CO2 and other gases in depleted reservoirs. The Triassic Montney Formation in western Canada hosts low-permeability gas reservoirs containing sealing faults that have previously been assumed to compartmentalize pressure domains. In this study, we show that the distribution of induced seismicity associated with hydraulic fracturing (HF) exhibits a statistically significant spatial correlation with zones of high lateral gradient in pore pressure. These high-gradient zones are interpreted as sealing fault systems. The largest induced seismicity sequence, including a 4.5 ML mainshock on 30 November 2018, occurred during HF treatments in two horizontal wells, between which there is an exceptionally large contrast (~10 MPa) in measured pore pressure. Numerical simulation of a simplified model of a hydraulic fracture intersecting a nearby vertical fault, followed by fault rupture using rate-and-state friction rheology, generates results that are in good agreement with observed strike-slip faulting near one of the HF wells. Our study demonstrates that sealing faults exhibit previously unrecognized behaviour that may be important for understanding induced seismicity risk. This article is part of the theme issue 'Induced seismicity in coupled subsurface systems'.
ABSTRACT
PURPOSE: Degradation or decomposition of the chemical herbicides by natural reagents after using can lead to produce various types of harmful intermediates. Ultrafiltration by the mixed matrix membranes blended with the graphene oxide/TiO2 can remove the residual herbicides from aqueous solution. METHODS: Graphene oxide/TiO2x% (x = 10, 30, 50%) was prepared by solvothermal method and blended by polysulfone to prepare GO/TiO2/PSf membranes for dynamic rejection of aqueous solutions of glyphosate, 2,4-D, butachlor, and trifluralin in a dead-end flow system. The blended membranes were also applied for the adsorption of herbicides in batch experiments. RESULTS: Addition of GO/TiO2 nanocomposite increased water flux from 7.3 for pure membrane to 211-326 kg/m2 h for mixed matrix samples in order to increase of the membrane porosity and surface hydrophilicity. The herbicides rejections were found in the range of 50-70% related to GO/TiO2 content. It was found that the membrane blended with 0.5 wt.% of GO/TiO2(10%) demonstrated the most efficiency. CONCLUSIONS: Details of dynamic filtration showed that the blended membrane acted based on the size exclusion mechanism. Adsorption experiments indicated that the strong attractions between H-bond donor sites of the herbicide and GO/TiO2 nanoparticles in membranes played a key role in the increase of adsorption of herbicides on the membrane.
ABSTRACT
The CdSe quantum dots (QDs) capped with 2-mercaptonicotinic acid (H2MN) were prepared through a controllable process at 80 °C. The prepared QDs were characterized by XRD, TEM, IR, UV-Vis and fluorescence (FL) techniques. It was found that the QDs were nearly mono-disperse with the diameters in the range of 8-10 nm. These QDs are capable to exhibit strong FL even in concentrated acidic media. They exhibit an enhanced fluorescence in the presence of Cr(VI), which was used for the determination of Cr(VI) in water samples. The linear range was found to be 1 × 10(-7)-6.0 × 10(-6) M with the RSD and DL of 0.92 % and 5 × 10(-8) M, respectively. Except that Ca(2+) and Fe(3+) which can be eliminated through a simple precipitation process, the other co-existent ions present in natural water were not interfered. The recoveries obtained for the added amounts of Cr(VI) were in the range of 96.9-103.2 %, which denote on application of the method, satisfactorily.
ABSTRACT
BACKGROUND: Properties of coated archwires, which have been introduced for esthetic demands during orthodontic treatments, along with the use of tooth-colored brackets, are not clear. The aim of this study is to compare the load-deflection and surface properties of coated superelastic archwires with conventional superelastic archwires in conventional and metal-insert ceramic brackets. MATERIALS AND METHODS: In this experimental study, 3 types of archwires including ultraesthetic polycoated, ultraesthetic epoxyresin coated and conventional (uncoated) superelastic nickel-titanium (NiTi) archwires were used in each of 2 types of brackets including conventional and metal-insert ceramic. To simulate oral environment, all specimens were incubated in artificial saliva using thermocycling model and then were tested in three-bracket bending test machine. Loading and unloading forces, plateau gap and end load deflection point (ELDP) were recorded. Archwires were investigated with a stereomicroscope before and after the experiment. Two-way ANOVA and Tukey tests were used at P<0.05. RESULTS: Epoxyresin archwires produced lower forces (19 to 310 gr) compared to polycoated (61 to 359 gr) and NiTi (61 to 415 gr) (P<0.0001). The maximum ELDP (0.43 mm) was observed in epoxyresin archwires (P<0.001). Coatings of some epoxyresin wires were torn and of polycoated wires peeled off. Conventional ceramic bracket produced higher loading forces with polycoated and NiTi archwires and lower unloading forces with all 3 types of archwires compared to metal-insert type (P<0.05). CONCLUSION: Epoxyresin-coated archwire had the lowest force and highest ELDP. Coatings were not durable in these experimental conditions. Conventional ceramic bracket produced higher frictional force compared to metal-insert type.
ABSTRACT
Our aim was further to clarify the diagnostic usefulness of N-terminal pro-B-type natriuretic peptide for detecting ventricular dysfunction in children, and its correlation with myocardial performance index and New York University Pediatric Heart Failure Index score. We also hypothesized that the level of this natriuretic peptide in the serum could predict the severity of diastolic abnormalities in children with cardiac failure. We enrolled 99 patients, aged from 3 months to 16 years, who had been referred for echocardiography to evaluate ventricular function. Echocardiographic evidence of left ventricular systolic and diastolic dysfunction was found in 20 and 42 patients, respectively. We classified these patients as having impaired relaxation, seen in 12 patients, pseudonormal patterns seen in 19 patients, and restrictive-like patterns of filling seen in 11 patients. The mean of the log-transformed values for N-terminal pro-B-type natriuretic peptide increased significantly according to the severity of diastolic dysfunction (p = 0.003, p = 0.022, p < 0.0001). A value of 178 pg/ml had a sensitivity of 88% and specificity of 81% for detecting abnormal diastolic function (p < 0.0001). Furthermore, the log-transformed values correlated with myocardial performance index (p < 0.0001) in a positive manner, and the levels increased significantly according to New York University Pediatric Heart Failure Index score, showing a linear correlation with a robust r value for regression (r = 0.89, p < 0.0001). Our findings suggest that higher levels of the peptide, having a good correlation with New York University Pediatric Heart Failure Index score and myocardial performance index, might be a suitable marker to rule out ventricular diastolic dysfunction in children.
