CFD Simulation of Rheological Model Effect on Cuttings Transport

Foam, as a non-Newtonian fluid, plays an important role in the underbalanced drilling technique in oil field development. The rheological properties of drilling fluids, such as foam, have a direct effect on flow characteristics and hydraulic performance. Two rheological models—the Herschel–Bulkley model and power law—were fitted to two foam systems in this study. Computational fluid dynamics (CFD) was used to simulate the effect of the rheological models on solid–liquid (cuttings transport) hydraulics in concentric and eccentric annulus during the foam drilling operation. The simulation results are compared to the experimental data from previous studies. The results of CFD using the power law model are in good agreement with experimental results in horizontal annulus with respect to the Herschel–Bulkley model with relative error less than 8%. Thus, for CFD cuttings transport for simulations in inclined and horizontal annulus, it is best to use the power law's rheological model parameters.     

Formulation of Risperidone as Self-Nanoemulsifying Drug Delivery System in Form of Effervescent Tablets

Risperidone is an atypical antipsychotic drug used to treat schizophrenia. This study aims to formulate risperidone as effervescent tablets to improve patient compliance. Different nanoemulsion combinations were loaded with risperidone to improve its poor water solubility then adsorbed on Aeroperl. The formula showing highest drug dissolution was formulated as effervescent tablets. Factorial design was applied for different tablet formulation variables and the prepared formulae were tested for different criteria in comparison with their corresponding formulae containing drug without nanoemulsion formulation. Statistical analysis was used to determine the most desirable tablet formula considering its Carr index, effervescence time, and drug release.     

Facile synthesis of 3-substituted quinazoline-2,4-dione and 2,3-di-substituted quinazolinone derivatives

3-Substituted quinazoline-2,4(1H,3H)-dione and 2,3-di-substituted quinazolineone derivatives attract considerable interest due to their pharmacological properties. In this paper, we report the synthesis of N-substituted-3-nitrophthalimide derivatives II?CIII, the reactions of phthalimide III with amines, hydrazines, and amino acid derivatives to synthesise a small library of 3-substituted-5-nitroquinazoline-2,4(1H,3H)-diones IV?CXIV and 2,3-di-substituted-6-nitro-quinazolineones XVIII?CXIX.     

Complexation ability of kryptofix 22DD with lanthanum (III) cation in some binary mixed non-aqueous solvents

The complex formation between lanthanum (III) cation with kryptofix 22DD was studied in acetonitrile–dimethylformamide (AN–DMF), acetonitrile–methanol (AN–MeOH), acetonitrile–ethylacetate (AN–EtOAc) and acetonitrile–ethanol (AN–EtOH) binary solvent solutions at different temperatures by using conductometric method. The conductance data show that in all cases, the stoichiometry of the complex formed between the macrocyclic ligand and the metal cation is 1:1 [ML]. The stability order of (kryptofix 22DD.La)³⁺ complex in the studied binary solvent solutions at 25 °C was found to be: AN–EtOAc>AN–EtOH>AN–MeOH>AN–DMF and in the case of pure non-aqueous solvents at 25 °C was: EtOAc>EtOH>MeOH>AN>DMF. A non-linear behavior was observed for changes of logK_f of (kryptofix 22DD.La)³⁺ complex versus the composition of the binary mixed solvents, which was explained in terms of solvent–solvent interactions and also the preferential solvation of the species involved in the complexation reaction. The values of standard thermodynamic parameters (?H _c°, ?S _c°) for formation of (kryptofix 22DD.La)³⁺ complex were obtained from temperature dependence of the stability constant using the van’t Hoff plots.The results show that in most cases, the (kryptofix 22DD.La)³⁺ complex is enthalpy destabilized, but entropy stabilized and the values of these thermodynamic quantities for formation of the complex are quite sensitive to the nature and composition of the mixed solvents solution.     

Role of novel oxazocine derivative as corrosion inhibitor for 304 stainless steel in acidic chloride pickling solutions

Inhibition of 304 stainless steel corrosion in acidic chloride pickling (1.0 M HCl) solutions by newly synthesized oxazocine derivative 4 as a corrosion inhibitor have been studied using weight loss, potentiodynamic polarization, and atomic absorption spectroscopy investigations. Potentiodynamic polarization curves show that the inhibitor behaves as a mixed-type. The adsorption of the inhibitor on the metal surface in the acid solution was found to obey Langmuir’s adsorption isotherm. The inhibition mechanism of the investigated inhibitor was discussed in terms of its adsorption on the metal surface. The relationship between the molecular structure and the inhibition efficiency was elucidated by quantum chemical calculations.     

Uranium recovery from UCF liquid waste by nanoporous MCM-41: breakthrough capacity and elution behavior studies

Adsorption and recovery of uranium by nanoporous MCM-41 from aqueous solutions (synthetic solution and uranium conversion facility liquid waste) were investigated by use of a fixed-bed column (1.2 cm diameter and 3.0 cm height). Adsorption was carried out at flow rates 0.2 and 0.5 mL min^?1, which correspond to retention times of 10 and 6 min. The maximum breakthrough capacity for uranium ions was achieved by use of nanoporous MCM-41 at the optimum pH of 3.6 and flow rate 0.2 mL min^?1 (61.95 μg g^?1). The Thomas and Yan models were applied to the experimental data, by use of linear regression, to determine the characteristics of the column for process design. The breakthrough curves calculated from the models were in good agreement with the experimental data. The elution behavior of uranium on nanoporous MCM-41 was studied with different eluents; the results showed that 0.1 M HCl is good eluent for uranium recovery. The regenerated column could be used in a multitude of adsorption–desorption cycles.     

Three Validated Methods for Simultaneous Determination of Ofloxacin and Dexamethasone in Binary Mixture

JPC – Journal of Planar Chromatography – Modern TLC - Three selective, precise, and accurate methods were developed and validated for the simultaneous determination of ofloxacin and...     

A heterogeneous and reusable nanopolymer-supported palladium catalyst for the copper- and phosphine-free Sonogashira coupling reaction under aerobic conditions in water

We report here the synthesis of a nanopolymer-supported palladium(II) complex catalyst, [PS-tet-Pd(II)] using a simple protocol. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR, and energy dispersive X-ray spectroscopy (EDS). PS-tet-Pd(II) proves to be a useful heterogeneous catalyst in the copper- and phosphine-free Sonogashira coupling reaction in water. The catalyst can be recovered from the reaction mixture by simple filtration and reused several times without any significant loss of catalytic activity.     

Fiber optical parametric amplifiers in optical communication systems

The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase‐insensitive amplifiers (PIAs) and phase‐sensitive amplifiers (PSAs) are considered. Low‐penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength‐ and time‐division multiplexed formats. High‐quality mid‐span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All‐optical amplitude regeneration of amplitude‐modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase‐modulated signals. A PSA with 1.1‐dB noise figure has been demonstrated, and preliminary wavelength‐division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength‐division multiplexed long‐haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long‐haul communication networks are discussed.

     

Lights and Shadows of DMSO as Solvent for Tin Halide Perovskites

In 2020 dimethyl sulfoxide (DMSO), the ever-present solvent for tin halide perovskites, was identified as an oxidant for Sn^II. Nonetheless, alternatives are lacking and few efforts have been devoted to replacing it. To understand this trend it is indispensable to learn the importance of DMSO on the development of tin halide perovskites. Its unique properties have allowed processing compact thin-films to be integrated into tin perovskite solar cells. Creative approaches for controlling the perovskite crystallization or increasing its stability to oxidation have been developed relying on DMSO-based inks. However, increasingly sophisticated strategies appear to lead the field to a plateau of power conversion efficiency in the range of 10–15 %. And, while DMSO-based formulations have performed in encouraging means so far, we should also start considering their potential limitations. In this concept article, we discuss the benefits and limitations of DMSO-based tin perovskite processing.