NANO-CHARACTERIZATION OF TYPE-G CEMENT SLURRY INCORPORATING NANOCLAY CURED UNDER HIGH TEMPERATURE AND PRESSURE

Abstract: Type-G cement slurry with various admixtures commonly used in oil/gas well cementing (OWC) incorporating 1, 2 and 3% nanoclay particles by weight of cement were produced. A water/cement ratio of 0.44 was used and the mixes were subjected to a temperature of 290° F and a pressure of 4666 psi for 48 hours. First, the effect of nanoclay on compressive strength evolution was investigated. Second elastic and viscoelastic characteristics of the cementitious mixes were characterized using nanoindentation. The nanoindentation tests enabled evaluating the maximum indentation depth, plastic depth, and the reduced elastic modulus. Furthermore, dwell time of 60 seconds was used to evaluate creep compliance of the cement mixes incorporating nanoclay. Fracture toughness was estimated from the nanoindentation data during the dwell loading period. Scanning electron microscope (SEM) and X-ray diffraction (XRD) microstructural analyses were conducted to explain the results observed using nanoindentation. Furthermore, finite element modeling was used to simulate the nanoindentation test and to extract the stress-strain Type-G cement material incorporating nanoclay and cured under high temperature and pressure. Moreover, The experimental observations showed that nanoclay improved compressive strength evolution with time compared with neat cement and eliminated strength retrogression problem. Furthermore, using 1 and 2% nanoclay resulted in insignificant change (-28 to +12%) of the reduced elastic modulus compared with neat cement. However, a high content of 3% nanoclay resulted in a significant increase of (+54%) in the reduced elastic modulus and a significant reduction in creep compliance compared with neat cement. Fracture analysis of nanoindentation data showed a significant improvement of fracture toughness due to the addition of nanoclay. XRD analysis and SEM investigations proved that the incorporation of nanoclay in the cement mix transforms the Calcium Hydroxide (CH) to calcium silicate hydrate (C-S-H) and reduced capillary porosity leading to higher elastic modulus and reduced creep compliance compared with neat cement. Finally, the extracted stress-strain curves using the finite element method shows that adding nanoclay resulted in stiffening OWC paste. The significance of nanoclay seems strongly dependent on the nanoclay content and the quality of its mixing with cement

Spectral, thermal, antimicrobial studies for silver(I) complexes of pyrazolone derivatives

Background: Synthesize new complexes of Ag(I) to enhance efficacy or stability and also, pharmacological activities on the operation of pyrazolone's biological properties. Results: Efficient and high yielding pathways starting from the versatile and readily available 3-methyl-1-phenyl-5-pyrazolone by Knoevenagel condensation of a sequence of 4-arylidene-3-methyl-1-phenyl-5-pyrazolone derivatives (2a-c) have been formed by the reaction of various substituted aromatic aldehydes Used as ligands to synthesize Ag(I) chelates. Synthesized compounds and their complexes have been characterized by elemental analysis, magnetic and spectroscopic methods (IR, 13C, 1HNMR, mass) and thermal analysis. The spectrophotometric determinations suggest distorted octaedral geometry for all complexes. Both ligands and their metal complexes have also been tested for their antibacterial and antifungal efficacy. Conclusions: Newly synthesized compounds have shown potent antimicrobial activity. The results showed that the complex 's high activity was higher than its free ligands, and that Ag(I)-L3 had the highest activity.This research is not funded though any source to This publication was supported by Qatar University, internal grant number QUCG-CAM-20/21-2. The findings achieved herein are solely the responsibility of the authors

Caprylamidopropyl Betaine as a Highly Efficient eco-friendly Corrosion Inhibitor for API X120 Steel in 1 M H2SO4

CORROSION inhibition of API X120 steel in a 1M sulfuric acid solution at altered temperatures was investigated utilizing a new eco-friendly surfactant (Caprylamidopropyl Betaine (CAPB)) by Gravimetric and electrochemical test (containing potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS). Surface characterization tests containing scanning electron microscopy (SEM), and atomic force microscopy (AFM) are utilized in the study. In addition, kinetic and thermodynamic parameters were measured and discussed. The overall results displayed that the corrosion rate of API X120 steel was significantly lowered with improving the temperature. The polarization curves lead to the CAPB inhibitor is influenced both anodic and cathodic reactions (mixed type inhibitor). Analyses of the surface topography designated an appreciable decrease in the surface roughness as the dose of the inhibitor in the solution improved. Energy-dispersive X-ray and X-ray photoelectron spectroscopy revealed the presence of adsorbed nitrogen atoms on the API X 120 steel surfaces. This work provides a promising eco-friendly inhibitor for mitigating the corrosion of API X120 steel in highly acidic brine environments

An efficient green ionic liquid for the corrosion inhibition of reinforcement steel in neutral and alkaline highly saline simulated concrete pore solutions

The effect of the green ionic liquid compound, Quaternium-32 (Q-32), on the corrosion inhibition performance of reinforcement steel, in a simulated concrete pore solution, was investigated at different temperatures and pH values, using electrochemical impedance spectroscopy (EIS). The inhibition efficiency was improved as the concentration of Q-32 and pH values were increased. However, it decreased as the temperature was raised. A Q-32 concentration of 20 µmol L–1 exhibited a 94% inhibition efficiency at 20 °C. The adsorption isotherm was evaluated using EIS measurements, and it was found to obey the Langmuir isotherm. The surface topography was examined using an atomic force microscope and scanning electron microscope. The effect of the Q-32 concentration with the highest corrosion efficiency on the mechanical properties of the mortars was also explained by flexure and compression techniques.The authors express their gratitude to the Center for Advanced Materials at Qatar University for technical support. Additionally, the authors are grateful to Qatar University for funding this work through the QUCG-CAM-20/21-2 Grant. The publication of this article was funded by the Qatar National Library

Electrospun highly corrosion-resistant polystyrene–nickel oxide superhydrophobic nanocomposite coating

A key challenge in producing superhydrophobic coatings (SHC) is to tailor the surface morphology on the micro-nanometer scale. In this work, a feasible and straightforward route was employed to manufacture polystyrene/nickel oxide (PSN) nanocomposite superhydrophobic coatings on aluminum alloys to mitigate their corrosion in a saline environment. Different techniques were employed to explore the influence of the addition of NiO nanoparticles to the as-prepared coatings. PSN-2 composite with ~ 4.3 wt% of NiO exhibited the highest water contact angle (WCA) of 155° ± 2 and contact angle hysteresis (CAH) of 5°. Graphic abstract: EIS Nyquist plots of 3 g of electrospun polystyrene coatings (a) without and with (b) 0.1, (c) 0.15, and (d) 0.2 g of NiO. [Figure not available: see fulltext.

Theoretical and experimental insights into the C-steel aqueous corrosion inhibition at elevated temperatures in 1.0M HCl via multi-carbonyl Gemini cationic surfactants

Despite corrosion being an inevitable process, researchers strive to control corrosion. In this study, our goal was to prepare two amido Gemini cationic surfactants, LAPG and MAPG, each with different alkyl chains and multiple carbonyl groups as rich electronic rich centers. We aimed to evaluate these surfactants as potential corrosion inhibitors for carbon steel (CS) in 1M HCl at temperatures of 25-55 ± 0.1°C. In theoretical investigations, DFT parameters and Mont Carlo simulation were run to predict the adsorption affinity and reactive sites of the LAPG and MAPG molecules. Their efficacy was investigated experimentally considering weight loss and electrochemical techniques. The Tafel polarization revealed that at 0.1mM of LAPG and MAPG, the corrosion current density (i corr) of CS was reduced to the lowest extent (75.56 and 53.82μAcm-2) compared to 529.3μAcm-2 in the absence of the inhibitors. EIS data suggests the enhancement of the thickness of the adsorbed layers of the studied compounds from the decrease of the double-layer capacitance C dl values. The Langmuir isotherm explained the adoption phenomena of these compounds at 25-55 ± 0.1°C. Activation and adsorption thermodynamic parameters predicted the chemisorption behavior of these molecules onto the steel surface. AFM and XPS tools confirm the CS surface protection due to these inhibitors' adsorbed layer. A parallel study showed the superiority of these corrosion inhibitors in HCl compared with those reported earlier, making these compounds highly promising corrosion inhibitors, especially in high-temperature acidic environments

Synthesis of Gemini cationic surfactants based on natural nicotinic acid and evaluation of their inhibition performance at C-steel/1 M HCl interface: Electrochemical and computational investigations

Herein, we prepare effective Gemini cationic surfactants (CSII, CSIV) and characterize them using FT-IR and 1HNMR spectroscopy. The adsorptive properties of CSII and CSIV at HCl/air and C-steel/HCl interfaces were examined with surface tension and electrochemical parameters, respectively. The critical micelle concentration (CMC) of the CSII and CSIV indicated their adsorption affinity at the HCl/air interface. Where, aliphatic chains increase surface coverage percentage and aid in surfactant adsorption. The electrochemical parameters of C-steel in 1 M HCl were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) at different temperatures. The charge transfer resistance of the C-steel electrode was enhanced from 28.2 Ω.cm2 to 770.79 and 831.45 Ω.cm2 after adding 5 × 10−4 M of CSII and CSIV, respectively. Both CSII and CSIV act as mixed inhibitors with inhibition performance exceeding 97% due to their highly adsorption affinity. The chemical adsorption affinity of these compounds is suggested by the higher adsorption energy (∆G*ads) values (>−40 kJ mol−1) according to the Langmuir isotherm model. The theoretical calculations including DFT, and Monte Carlo simulation (MCs) provide insight into the relationship between corrosion inhibition and molecular structure, where the calculated parameters agree with the experimental results

Capsaicin ameliorate pulmonary fibrosis via antioxidant Nrf-2/ PPAR- γ pathway activation and inflammatory TGF-β1/ NF-κB/COX II pathway inhibition

Bleomycin is an effective antibiotic with a significant anticancer properties, but its use is limited due to its potential to induce dose-dependent pulmonary fibrosis. Therefore, this study aimed to assess the therapeutic potential of Capsaicin as an additional treatment to enhance patient tolerance to Bleomycin compared to the antifibrotic drug Pirfenidone. Pulmonary fibrosis was induced in rats through by a single intratracheal Bleomycin administration in day zero, followed by either Capsaicin or Pirfenidone treatment for 7 days. After the animals were sacrificed, their lungs were dissected and examined using various stains for macroscopic and histopathological evaluation. Additionally, the study assessed various antioxidant, anti-inflammatory, and antifibrotic parameters were assessed. Rats exposed to Bleomycin exhibited visible signs of fibrosis, histopathological alterations, increased collagen deposition, and elevated mucin content. Bleomycin also led to heightened increased inflammatory cells infiltration in the bronchoalveolar lavage, elevated fibrosis biomarkers such as hydroxyproline, alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β1), increased inflammatory markers including tumor necrosis factor-alpha (TNF-α), interlukine-6 (Il-6), interlukine-1β (Il-1β) nuclear factor-kappa B (NF-κB), and Cyclooxygenase-2 (COX-2), and transforming growth factor-beta (TGF-β1),. Furthermore, it reduced the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ), increased oxidative stress biomarkers like nitric oxide (NO), malondialdehyde (MDA), myeloperoxidase (MPO) and protein carbonyl. Bleomycin also decreased the expression of nuclear factor erythroid 2–related factor 2 (Nrf-2), reduced glutathione (GSH), total antioxidant capacity, and the activities of catalase and superoxide dismutase (SOD). Treating the animals with Capsaicin and Pirfenidone following Bleomycin exposure resulted in improved lung macroscopic and microscopic characteristics, reduced collagen deposition (collagen I and collagen III) and mucin content, decreased inflammatory cell infiltration, lowered levels of hydroxyproline, α-SMA, and TGF-β1, decreased TNF-α, Il-6, Il-1β, NF-κB, and COX-2, increased PPAR-γ and Nrf-2 expression, and improvement improved in all oxidative stress biomarkers. In summary, Capsaicin demonstrates significant antifibrotic activity against Bleomycin-induced lung injury that may be attributed, at least in part, to the antioxidant and anti-inflammatory activities of Capsaicin mediated by upregulation of PPAR-γ and Nrf-2 expression and decreasing. TGF-β1, NF-κB and COX II proteins concentrations

Rational synthesis of one-dimensional carbon nitride-based nanofibers atomically doped with Au/Pd for efficient carbon monoxide oxidation

Controlled synthesis of carbon nitride nanostructures doped with noble metal-based catalysts is important in various catalytic applications. Herein, we developed a scalable, facile, and template-free approach for one-pot synthesis of one-dimensional gC3N4 nanofibers co-doped with Au and Pd donated as (Au/Pd/gC3N4NFs). The developed method tailored the high mass production of uniform gC3N4 nanofibers with a great surface area of (85 m2 g−1) and coherently co-doped with Au and Pd. Intriguingly, the complete CO oxidation temperature of Au/Pd/gC3N4NFs (144 °C) is significantly lower than that of Pd/gC3N4NFs (191 °C) and Au/gC3N4NFs (205 °C). The superior activity of Au/Pd/gC3N4NFs is attributed to the combination between outstanding inherent catalytic merits of Au/Pd and the unique physicochemical properties of gC3N4 nanofibers. Our newly designed simple approach may open the way for utilization of gC3N4 nanofibers in CO oxidation reaction.This publication was supported by Qatar University International Research Collaboration Co-Funds (IRCC) Grant No IRCC179 . The findings achieved herein are solely the responsibility of the authors.Scopu

Antimicrobial Potency and <i>E. coli</i> β-Carbonic Anhydrase Inhibition Efficacy of Phenazone-Based Molecules

In this investigation, 4-antipyrinecarboxaldhyde was reacted with methyl hydrazinecarbodithioate to afford the carbodithioate derivative 3. The as-prepared carbodithioate derivative 3 is considered to be a key molecule for the preparation of new antipyrine-1,3,4-thiadiazole-based molecules (4–9) through its reaction with the appropriate hydrazonoyl halides. Furthermore, a typical Biginelli three-component cyclocondensation reaction involving ethyl acetoacetate, 4-antipyrinecarboxaldhyde, and thiourea under the standard conditions is carried out in the presence of sulfuric acid to afford the corresponding antipyrine–pyrimidine hybrid molecule (10). The latter was submitted to react with hydrazine monohydrate to provide the corresponding hydrazide derivative (11) which, under reaction with ethyl acetoacetate in refluxing ethanol containing catalytic amount of acetic acid, afforded the corresponding derivative (12). The structure of the newly synthesized compounds was affirmed by their spectral and microanalytical data. We also screened for their antimicrobial potential (ZOI and MIC) and conducted a kinetic study. Additionally, the mechanism of biological action was assessed by a membrane leakage assay and SEM imaging technique. Moreover, the biological activities and the binding modes of these compounds were further supplemented by an in silico docking study against E. coli β-carbonic anhydrase. The amount of cellular protein released by E. coli is directly correlated to the concentration of compound 9, which was found to be 177.99 µg/mL following treatment with 1.0 mg/mL of compound 9. This finding supports compound 9’s antibacterial properties and explains how the formation of holes in the E. coli cell membrane results in the release of proteins from the cytoplasm. The newly synthesized compounds represent acceptable antimicrobial activities with potential action against E. coli β-carbonic anhydrase. The docking studies and antimicrobial activity test proved that compound (9) declared a greater activity than the other synthesized compounds