Novel biphenylidene-thiopyrimidine derivatives as corrosion inhibitors for carbon-steel in oilfield produced water.

The inhibiting efficiency of three newly synthesized organic compounds:5-((4'-(dimethylamino)-[1,1'-biphenyl]-4-yl)methylene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione (HM-1228), 5-((4'-(dimethylamino)-[1,1'-biphenyl]-4-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione (HM-1227) and 5-((4'-(dimethylamino)-[1,1'-biphenyl]-4-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1226) in oilfield produced water on the corrosion of carbon steel has been examined via electrochemical measurements; potentiodynamic polarization (PDP) and electrochemical impedance (EIS) techniques. The adsorption of these compounds on the surface of carbon steel followed Langmuir isotherm. In addition, the surface morphology of uninhibited and inhibited carbon steel was examined by Atomic Force Microscopy (AFM), observing surface improvement when carbon steel samples exposed to the inhibited corrosive solutions. The average surface roughness (Ra) in oilfield produced water solution in the presence of 0.5 mM of HM-1228 inhibitor was 138.28 nm compared to the uninhibited surface 571.62 nm. To explore the corrosion inhibition mechanism, quantum chemical calculations and Monte Carlo simulations were utilized. The HM-1228 inhibitor demonstrated the highest corrosion inhibition efficiency at 94.8% by PDP measurements. The higher corrosion inhibition of compound HM-1228 can be attributed to the presence of di-N-ethyl groups that enhance both electron donating ability and lipophilic properties.

Electrochemical Investigation of C-Steel Corrosion Inhibition, In Silico, and Sulfate-Reducing Bacteria Investigations Using Pyrazole Derivatives.

The inhibitory impact of the two synthesized pyrazole derivatives (3 and 4) toward metallic and microbial corrosion was investigated. Using open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy, it was possible to determine their ability to prevent the corrosion of C-steel in 1 M HCl, which was significantly enhanced with increasing concentration (ex. 93%). They act as mixed-type inhibitors, according to polarization curves. The compounds under investigation were adsorbed on a C-steel surface in 1 M HCl following the Langmuir isotherm model. The double-layer capacitance was decreased, and the charge transfer resistance (Rct) was raised due to the examined inhibitors' adsorption. Investigating changes in the surface morphology and confirming the corrosion inhibition mechanism are done using scanning electron microscopy. Density functional theory calculations and Monte Carlo simulations were also conducted to show the adsorption affinity of the understudied compounds over the steel substrate in neutral and protonated forms. Furthermore, the antimicrobial performance of the two synthesized pyrazoles against sulfate-reducing bacteria was evaluated, and the recorded inhibition efficiency was 100%. The current research shows important developments in producing highly effective anticorrosion and antimicrobial pyrazole derivatives.

Novel cationic aryl bithiophene/terthiophene derivatives as corrosion inhibitors by chemical, electrochemical and surface investigations.

Two novel bithienyl fluorobenzamidine derivatives namely, 4-([2,2':5',2''-terthiophen]-5-yl)-2-fluorobenzamidine hydrochloride salt (MA-1615), 5'-(4-amidino-3-fluorophenyl)-[2,2'-bithiophene]-5-carboxamidine dihydrochloride salt (MA-1740) were synthesized, characterized and their corrosion inhibition properties were evaluated by electrochemical methods for carbon steel (C-steel) in 1 M HCl. Experimental investigations revealed that the inhibition effectiveness of the investigated inhibitors (INHs) by the Tafel polarization method followed the order: MA-1740 (96.9%) > MA-1615 (95.6%), demonstrating higher efficiency than inhibitors of similar structure reported in the literature. The investigated bithiophene derivatives exhibit mixed-type corrosion inhibition characteristics by blocking the active sites on the surface of C-steel. EIS study revealed that the INHs behave as interface-type corrosion inhibitors. UV-Visible spectrometric measurements confirmed a complex formation between the Fe2+ cation released during the corrosion reactions and inhibitor molecules.

High-Density Polyethylene Waste (HDPE)-Waste-Modified Lube Oil Nanocomposites as Pour Point Depressants.

Sustainability metrics have been established that cover the economic, social, and environmental aspects of human activities. Reduce, reuse, and recycle (3R) strategy targets solid waste management in the waste generation sectors. The purpose of this work is to study the possibility of using various plastic wastes containing high-density polyethylene (HDPE) and high-density polyethylene nanoclay (PMON) as polymer additives to modify lubricating oil. The structure of these additives was elucidated by Fourier transform infrared (FTIR) spectra, and the particle size of PMON was determined by dynamic light scattering (DLS). The thermal stability of HDPE and nanoclay HDPE (PMON) was studied, which showed higher thermal stability, and these additives completed degradation above 500 °C. The performance of HDPE and nanoclay HDPE (PMON) in lubricating oil was evaluated as pour point depressants by standard ASTM methods. The results showed that the efficiency of these additives increases with the decrease in the dose of these additives and lubricating oil treated with HDPE at 0.25% dosage lowers PPT to -30 °C, while lubricating oil treated with nanoclay HDPE (PMON7) at 0.25% dosage reduces PPT to -36 °C. Photomicrographic analysis was conducted to study accumulations and modifications in the wax crystal morphology in lube oil without and with HDPE and nanoclay HDPE (PMON7). Photomicrographs revealed that wax morphology changes due to effective pour point depressants on crystal growth.

Preparation and Characterization of Eco-Friendly Spent Coffee/ENR50 Biocomposite in Comparison to Carbon Black.

This study investigates the impact of spent coffee biochar (Biochar) compared to carbon black (CB) as a partial replacement for carbon black in epoxidized natural rubber (ENR). Particle size and elemental analysis were used to characterize the biochar and CB. Cure characteristics, tensile, thermal, and morphological properties on the effect of biochar and CB as filler were studied. It was found that incorporating 10 phr of spent coffee biochar could improve the composites' tensile properties and thermal performance compared to carbon black. However, the addition of biochar significantly affects the maximum torque compared to CB and delays the vulcanization time. SEM study shows that biochar has a strong effect on the morphology of composite films. The FTIR graph reveals no substantial difference between compounds with biochar and CB. According to the thermal calorimetric study, the thermal stability of ENR-Biochar is higher than that of ENR-CB. Additionally, these findings suggest that the utilization of spent coffee as a sustainable biochar could be further explored, but little has been done in epoxidized natural rubber (ENR).

Construction, petro-collecting/dispersing capacities, antimicrobial activity, and molecular docking study of new cationic surfactant-sulfonamide conjugates.

Surfactants with their diverse activities have been recently involved in controlling the spread of new coronavirus (COVID-19) pandemic as they are capable of disrupting the membrane surrounding the virus. Using hybrids approach, we constructed a novel series of cationic surfactant-sulfonamide conjugates (3a-g) through quaternization of the as-prepared sulfonamide derivatives (2a-g) with n-hexadecyl iodide followed by structural characterization by spectroscopy (IR and NMR). Being collective properties required in petroleum-processing environment, the petro-collecting/dispersing capacities on the surface of waters with different degrees of mineralization, and the antimicrobial performance against microbes and sulfate-reducing bacteria (SRB) that mitigate microbiological corrosion were investigated for the synthesized conjugates. Among these conjugates, 3g (2.5% aq. solution) exhibited the strongest ability to disperse the thin petroleum film on the seawater surface, whereas KD is 95.33% after 96 h. In diluted form, 3f collected the petroleum layer on distilled water surface (Kmax = 32.01) for duration exceeds 4 days. Additionally, almost all compounds revealed high potency and comparable action with standard antimicrobials, especially 3b and 3f, which emphasize their role as potential biocides. Regarding biocidal activity against SRB, 3g causes a significant reduction in the bacterial count from 2.8 × 106 cells/mL to Nil. Moreover, the conducted molecular docking study confirms the strong correlation between RNA polymerase binding with bioactivity against microbes over other studied proteins (threonine synthase and cyclooxygenase-2).

Synthesis, Characterization, and Computational Chemical Study of Aliphatic Tricationic Surfactants as Corrosion Inhibitors for Metallic Equipment in Oil Fields.

Aliphatic tricationic surfactants were prepared by the esterification reaction, followed by a quaternization reaction to protect oil well facilities from corrosion problems. Microelemental analysis and Fourier transform infrared and 1H NMR spectroscopic techniques were performed to explore the obtained motifs. The performance of these amphiphiles as inhibitors for metallic S90 steel corrosion in formation water was investigated through electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy). The results revealed significant inhibition effectiveness improvement with increasing concentrations of these amphiphiles. Its maximum inhibition efficiency reaches 93.07% at 250 ppm for the compound (AED). Potentiodynamic polarization graphs demonstrated that tricationic amphiphiles behave as mixed-type inhibitors. In addition, the adsorption of the tricationic surfactant at the S90 steel surface followed Langmuir isotherm. Atomic force microscopy revealed that a protective layer formed at the surface of S90 steel caused the inhibition of corrosion. During the inhibition procedure of S90 steel corrosion, theoretical research has been performed to validate electrochemical experiments and to clearly demonstrate the mechanism of these amphiphiles. Finally, quantum chemical calculations were calculated to achieve the justification for the obtained empirical results.

A new chronotype of Schistosoma mansoni: adaptive significance.

OBJECTIVES: To optimise host-to-host transmission, digenean trematodes (parasites) synchronize their cercarial emission patterns with the aquatic activities of their vertebrate hosts. Schistosoma mansoni has a strictly diurnal shedding pattern involving two circadian chronotypes: an early shedding pattern with a mean peak occurring at 11:00 h and a late pattern with a mean peak occurring at 16:00 h. We analysed the cercarial emergence pattern of three schistosome populations from Oman where S. mansoni is resurgent. METHODS: For each schistosome population, the cercarial emergence pattern was assessed hourly over several days. Because we identified a new chronotype hitherto unknown in S. mansoni, we undertook taxonomic characterisation based on egg morphology and mitochondrial DNA sequence (COX1). RESULTS: Taxonomic characterisation revealed that the three schistosome populations belong to the species S. mansoni. Hence, this is the first report of this species exhibiting a nocturnal chronotype, with the mean peak occurring at 20:00 h. We interpreted the new chronotype as being the result of a lateral transfer of S. mansoni from humans to Rattus rattus. CONCLUSION: The cercarial emergence pattern of S. mansoni from Oman is circadian, exhibiting either a diurnal or a nocturnal phenotype.

Fractional doses of inactivated poliovirus vaccine in Oman.

BACKGROUND: We conducted a clinical trial of fractional doses of inactivated poliovirus vaccine administered to infants in Oman, in order to evaluate strategies for making the vaccine affordable for use in developing countries. METHODS: We compared fractional doses of inactivated poliovirus vaccine (0.1 ml, representing one fifth of a full dose) given intradermally with the use of a needle-free jet injector device, with full doses of vaccine given intramuscularly, with respect to immunogenicity and reactogenicity. Infants were randomly assigned at birth to receive either a fractional dose or a full dose of inactivated poliovirus vaccine at 2, 4, and 6 months. We also administered a challenge dose of monovalent type 1 oral poliovirus vaccine at 7 months and collected stool samples before and 7 days after administration of the challenge dose. RESULTS: A total of 400 infants were randomized, of whom 373 (93.2%) fulfilled the study requirements. No significant baseline differences between the groups were detected. Thirty days after completion of the three-dose schedule, the rates of seroconversion to types 1, 2, and 3 poliovirus were 97.3%, 95.7%, and 97.9%, respectively, in the fractional-dose group, as compared with 100% seroconversion to all serotypes in the full-dose group (P=0.01 for the comparison with respect to type 2 poliovirus; results with respect to types 1 and 3 poliovirus were not significant). The median titers were significantly lower in the fractional-dose group than in the full-dose group (P<0.001 for all three poliovirus serotypes). At 7 months, 74.8% of the infants in the fractional-dose group and 63.1% of those in full-dose group excreted type 1 poliovirus (P=0.03). Between birth and 7 months, 42 hospitalizations were reported, all related to infectious causes, anemia, or falls, with no significant difference between vaccination groups. CONCLUSIONS: These data show that fractional doses of inactivated poliovirus vaccine administered intradermally at 2, 4, and 6 months, as compared with full doses of inactivated poliovirus vaccine given intramuscularly on the same schedule, induce similar levels of seroconversion but significantly lower titers. (Current Controlled Trials number, ISRCTN17418767.)