Portland cement (PC) is known for its environmental and technical concerns and massive energy consumption during manufacturing. Geopolymer cement is a promising technology to totally replace the use ...of PC in the oil and gas industry. Although geopolymers are widely used in the construction industry, it is yet to see a full-scale application in the petroleum industry. High-density geopolymer cement development is essential to substitute heavy-weight Portland cement slurries for high pressure well cementing applications. Sedimentation issue is associated with high-density cement slurries which use high specific gravity solids such as weighting materials. This problem causes heterogeneity and density variation along the cemented sections. The main target of this work is to evaluate the use of perlite powder to address the sedimentation issue in the heavy weight geopolymer systems. Hematite-based Class F fly ash (FFA) geopolymer cement slurries with perlite concentrations of 0, 1.5, and 3% by weight of binder (BWOB) were prepared. The sedimentation problem was investigated using three techniques: API method, nuclear magnetic resonance (NMR), and computed tomography (CT) scan. The perlite effects on different geopolymer properties such as unconfined compressive strength (UCS), porosity, elastic and rheological properties were assessed. The results proved that perlite incorporation in high-density hematite-based FFA geopolymer significantly reduced sedimentation issue by increasing yield point and gel strength. NMR and CT scan showed that perlite decreases porosity and density variation across the geopolymer samples. The UCS increased with increasing perlite percentage from 0 to 3%. The measured Young's moduli (YM) and Poisson's ratios (PR) showed that the developed perlite based geopolymer systems are considered more flexible than Class G cement systems. It was found that the optimum perlite concentration is 3% BWOB for tackling sedimentation and developing a slurry with acceptable mixability and rheological properties.
Rivers transport terrestrial microplastics (MP) to the marine system, demanding cost-effective and frequent monitoring, which is attainable through remote sensing. This study aims to develop and test ...microplastic concentration (MPC) models directly by satellite images and indirectly through suspended sediment concentration (SSC) as a proxy employing a neural network algorithm. These models relied upon high spatial (26 sites) and temporal (198 samples) SSC and MPC data in the Tisza River, along with optical and active sensor reflectance/backscattering. A feedforward MLP neural network was used to calibrate and validate the direct models employing k-fold cross-validation (five data folds) and the Optuna library for hyperparameter optimization. The spatiotemporal generalization capability of the developed models was assessed under various hydrological scenarios. The findings revealed that hydrology fundamentally influences the SSC and MPC. The indirect estimation method of MPC using SSC as a proxy demonstrated higher accuracy (R
= 0.17-0.88) than the direct method (R
= 0-0.2), due to the limitations of satellite sensors to directly estimate the very low MPCs in rivers. However, the estimation accuracy of the indirect method varied with lower accuracy (R
= 0.17, RMSE = 12.9 item/m
and MAE = 9.4 item/m
) during low stages and very high (R
= 0.88, RMSE = 7.8 item/m
and MAE = 10.8 item/m
) during floods. The worst estimates were achieved based on Sentinel-1. Although the accuracy of the MPC models is moderate, it still has practical applicability, especially during floods and employing proxy models. This study is one of the very initial attempts towards MPC quantification, thus more studies incorporating denser spatiotemporal data, additional water quality parameters, and surface roughness data are warranted to improve the estimation accuracy.
Laboratory investigations supported this diagnosis: a lupus anticoagulant test was positive and the levels of anticardiolipin IgM and anti-β2 glycoprotein I IgG antibodies—markers of the ...antiphospholipid syndrome—were increased. Pleasingly, the patient's clinical condition improved remarkably, and his left ventricular function increased with an ejection fraction of 43%; the mitral valve mass also reduced in size to 0·5 cm × 0·4 cm (figure and video 4). Supplementary video 3 Transoesophageal echocardiograms, three-dimensional transoesophageal echocardiogram, and four-chamber cine cardiac steady state free precession MRI all confirm that the mass is attached to the base of the posterior leaflet of the mitral valve.
Sclerostin, a Wnt-signalling inhibitor, is an established negative regulator of bone formation. However, data regarding its potential importance in vascular disease are less clear. Common carotid ...artery media thickness (CIMT) assessment and plaque identification using ultrasound imaging are well-recognized tools for identifying and monitoring atherosclerosis. The aim of the present study is to examine the relationship between serum sclerostin and subclinical atherosclerosis (as evidenced by CIMT).
This cross-sectional study included 50 subjects with T2DM and 20 subjects as a control group. Multivariable linear regression models were used to assess the association of sclerostin with subclinical atherosclerosis.
Serum sclerostin levels in T2DM patients were significantly higher compared to the control group (167.16 ± 63.60 versus 85.98 ± 23.74 pg/ml, P < 0.0001). A concentration of ≥162.5 pg/ml showed a sensitivity of 90% and a specificity of 86.67% to detect an increased risk of subclinical atherosclerosis. Univariate analysis revealed a significant positive correlation between serum sclerostin and CIMT (r = 0.635, P < 0.001). Sclerostin concentrations remained independently associated with CIMT (β = 63.188 6.919–119.456, P = 0.017) after adjusting for age and gender.
Our data suggest a positive correlation between serum sclerostin level and subclinical atherosclerosis in subjects with type 2 diabetes mellitus.
•Spirulina extract (SPE) maximized Phaseolus vulgaris production in a heavy metals-contaminated saline soil.•SPE efficiently improved photosynthesis and plant integrity under stress conditions.•SPE ...catalyzed more antioxidant activities, attenuating the damage of oxidative stress markers.•SPE efficiently restored nutrients and minimized toxic metals in the plant edible part under stress conditions.•SPE was the most effective treatment when used as a soil addition (80 mg hill−1; rhizosphere area of two plants) in integration with foliar spray (40 mg plant−1).
Plants have to cope with several abiotic stresses, including salinity and heavy metals (HMs). Under these stresses, several extracts have been used as effective natural biostimulants, however, the use of Spirulina platensis (SP) extract (SPE) remains elusive. The effects of SPE were evaluated as soil addition (SA) and/or foliar spraying (FS) on antioxidant defenses and HMs content of common bean grown in saline soil contaminated with HMs. Individual (40 or 80 mg SPE/hill added as SA or 20 or 40 mg SPE/plant added as FS) or integrative (SA+FS) applications of SPE showed significant improvements in the following order: SA-80+FS-40 > SA-80+FS-20 > SA-40+FS-40 > SA-40+FS-20 > SA-80 > SA-40 > FS-40 > FS-20 > control. Therefore, the integrative SA+FS with 40 mg SP/plant was the most effective treatment in increasing plant growth and production, overcoming stress effects and minimizing contamination of the edible part. It significantly increased plant growth (74%–185%) and yield (107%–227%) by enhancing net photosynthetic rate (78.5%), stomatal conductance (104%), transpiration rate (124%), and contents of carotenoids (60.0%), chlorophylls (49%–51%), and NPK (271%–366%). These results were concurrent with the marked reductions in malondialdehyde (61.6%), hydrogen peroxide (42.2%), nickel (91%–94%), lead (80%–9%), and cadmium (74%–91%) contents due to the improved contents of glutathione (87.1%), ascorbate (37.0%), and α-tocopherol (77.2%), and the activities of catalase (18.1%), ascorbate peroxidase (18.3%), superoxide dismutase (192%), and glutathione reductase (52.2%) as reinforcing mechanisms. Therefore, this most effective treatment is recommended to mitigate the stress effects of salinity and HMs on common bean production while minimizing HMs in the edible part.
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Lake Burullus is one of the most important coastal lakes in Egypt, as it participates with a considerable amount of fish yield in Egypt. Despite its importance, it is considered as a vulnerable lake, ...since it is subjected to significant environmental changes caused by various anthropogenic activities. Severe deterioration of its water quality status, as well as a decrease in its water area, has been noticed throughout the last four decades. The main objective of this study is to evaluate the ability of remote sensing for assessing the water quality status of the lake for the period from August 2010 to August 2013. Remote sensing technique was used to retrieve and predict the lake water quality parameter records through the assessment period (August 2010 to August 2013). Stepwise multi-linear regression technique was used to correlate between the field measurements of water quality parameters and the reflectance of remote sensing imageries, and then the derived models were validated. The results revealed the critical status of water quality conditions of the lake, particularly of its southern and southeastern parts. The results showed also that some water quality parameters (Chl-a, TSS, pH, Fe, Zn, Cr, and NH
4
) can be retrieved from remote sensing imageries with reasonable accuracy (
R
2
= 0.86, 0.67, 0.65, 0.63, 0.62, 0.61, and 0.6, respectively), while the water quality parameters, which can be predicted, based on calibrated and validated regression models are TSS and Chl-a, with acceptable accuracy (
R
2
= 0.6 and 0.43, respectively). Lake Burullus needs urgent plans and strategies to protect its water quality from the potential hazards of human activities. The study proved the ability of remote sensing as an effective technique to monitor the changes in water quality conditions of shallow coastal lagoons and to predict with some water quality parameters without field measurements; therefore, it is highly recommended to be used by decision makers.
Many aspects relating to thermal, economic, and reliability challenges are involved while designing a Photovoltaic/Thermal (PV/T) system under high performance. When compared to standard PV systems, ...PV/T systems are more effective in locations with high irradiance. To eliminate the excess heat from a PVT system, an optimal cooling system is necessary, resulting in improved the temperature of PV module which directly effect on the overall performance. The current study is focused on a new economic and essay construction thin and thick (3 mm and 15 mm) cooling cross-fined channel box that have covered modeled. In terms of cell temperature and output cooling water temperature, the effects of various irradiation levels and cooling water flow rates are examined. Software that is based on finite elements, the problem was solved numerically in a three-dimensional model using ANSYS (19.2). It has been discovered that when the cooling fluid flow rate increases, the average surface temperature distribution of PV/T system and outlet cooling water temperature are reduced for thin and thick box heat exchanger and ideal with a cooling fluid flow rate of 3 L/min. The average surface temperature and water-cooling temperature are 30.7 °C and 38.9 °C for thin box heat exchanger, respectively, whereas for thick box heat exchanger are 30.8 °C and 32.4 °C, respectively, under solar irradiance 1000 W/m2 and optimal flow rate.
Core-shell refractory plasmonic nanoparticles are used as excellent nanoantennas to improve the efficiency of lead-free perovskite solar cells (PSCs). SiO
is used as the shell coating due to its high ...refractive index and low extinction coefficient, enabling the control over the sunlight directivity. An optoelectronic model is developed using 3D finite element method (FEM) as implemented in COMSOL Multiphysics to calculate the optical and electrical parameters of plain and ZrN/SiO
-modified PSCs. For a fair comparison, ZrN-decorated PSCs are also simulated. While the decoration with ZrN nanoparticles boosts the power conversion efficiency (PCE) of the PSC from 12.9% to 17%, the use of ZrN/SiO
core/shell nanoparticles shows an unprecedented enhancement in the PCE to reach 20%. The enhancement in the PCE is discussed in details.
The emergence of novel RNA viruses like SARS-CoV-2 poses a greater threat to human health. Thus, the main objective of this article is to develop a new mathematical model with a view to better ...understand the evolutionary behavior of such viruses inside the human body and to determine control strategies to deal with this type of threat. The developed model takes into account two modes of transmission and both classes of infected cells that are latently infected cells and actively infected cells that produce virus particles. The cure of infected cells in latent period as well as the lytic and non-lytic immune response are considered into the model. We first show that the developed model is well-posed from the biological point of view by proving the non-negativity and boundedness of model's solutions. Our analytical results show that the dynamical behavior of the model is fully determined by two threshold parameters one for viral infection and the other for humoral immunity. The effect of antiviral treatment is also investigated. Furthermore, numerical simulations are presented in order to illustrate our analytical results.
An ultra-sensitive sensor of dopamine is introduced. The sensor is constructed by encapsulating platinum nanoparticles (PtNPs) between reduced graphene oxide (GR) nanosheets. The sandwiched PtNPs ...between GR layers acted as a spacer to prevent aggregation and provided a fine connection between the GR nanosheets to provide fast charge transfer. This specific orientation of the GR nanosheets and PtNPs on the graphite pencil electrode (GPE) substantially improved the electrocatalytic activity of the sensor. The synthesized graphene oxide and the fabricated sensor were comprehensively characterized by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, field emission-scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and square wave voltammetry (SWV). The value of the charge transfer coefficient (
α
), apparent heterogeneous electron transfer rate constant (
k
s
), and electroactive surface area for dopamine were found to be about 0.57, 8.99 s
−1
, and 0.81 cm
2
, respectively. The developed sensor is highly sensitive towards dopamine, and the detection limit is 9.0 nM. The sensor response is linear for dopamine concentration from 0.06 to 20 μM (
R
2
= 0.9991). The behavior of the sensor for dopamine in the presence of a high concentration of
l
(+) Ascorbic acid and other potential interferents was satisfactory. High recovery percentage between 90% and 105% in the human urine sample, good reproducibility, and facile fabrication of the electrode make it a good candidate for dopamine sensing.
An efficient, highly sensitive, and selective electrochemical sensor using PtNPs sandwiched graphene layered modified graphite pencil electrode.
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