Oil Base Mud. Part I: Synthesis of Some Local Surfactants Used as Primary Emulsifiers for Oil Base Mud and Evaluation of Their Rheology Properties

Six oil soluble nonionic surfactants with different HLBs have been prepared. Their HLBs situate between 3.9 and 6.7. Transesterification was carried out for glycerol and triethanol amine with oleic acid at different moles to obtain six emusilifiers. They named glycerol momooleate (I), glycerol diooleate (II), glycerol trioleate (III), triethanol amine mono-, di- and tri-oleate (IV), (V,) and (VI). The chemical structure was confirmed using; the elemental analysis, FTIR and ¹HNMR. They were evaluated as a primary emulsifiers (PE) for thdrilling fluids (oil base mud) comparing with a currently used primary emulsifier (Fc). The water in oil base mud (w/o emulsions) was prepared. The concentration of emulsifiers and their HLB exhibited interesting rheology properties including shear-thinning behavior, yield value, viscoelastic effects, thixtropy, gel strength, and filtration loss. The rheology properties of such emulsions strongly depended on the average size distribution of the dispersed droplets that could be varied both with the bulk concentration and HLB value of the emulsifiers. The interfacial and surface properties of these emulsifiers suggest that the droplet size of the dispersed phase and bulk concentration are strongly related to the HLB value of emulsifiers. The w/o emulsion (mud formulation) stability is sensitive to the droplet size of the dispersed phase and HLB value of the used emulsifier. The results were discussed on the light the chemical structure of the primary emulsifiers and the emulsion ingredients.     

Synthesis of Some Oil Spill Dispersants Based on Sorbitol Esters and Their Capability to Disperse Crude Oil on Seawater to Alleviate Its Accumulation and Environmental Impact

In this respect mono‐, di‐, and tri‐ sorbitol oleate esters [SMO, SDO, and STO] were prepared and then ethoxylated using ethylene oxide to obtain six sorbitol esters at different ethylene oxide content (e.o=5, 12, 15, 20, 35, and 45). They were tested as oil spill dispersants individually and in blends. From the obtained data, it was found that the blends are more effective than the corresponding individual surfactants. The maximum dispersion capability for the prepared surfactants was obtained at HLB range from 9 to 11 for the both individual surfactants and blends. The increase of total carbon number in the surfactant alkyl group leads to increase dispersion capability of the dispersant. The wide range of ethylene oxide content was used, but the maximum dispersion efficiency was obtained at ethylene oxide=20 in E(20)STO. Meanwhile, the dispersion capability increases when the interfacial tension decreases.     

The Surface and Thermodynamic Properties of Ethoxylated Sodium Monoalkyl Sulfosuccinate Surfactants

A series of ethoxylated sodium monooctyl sulfosuccinates [E(n)SMOSS] and ethoxylated sodium monolauryl sulfosuccinates [E(n)SMLSS] have different units of ethylene oxide (n = 9, 14, 23) were synthesized. The surface and thermodynamic properties of these surfactants have been compared with sodium dioctyl sulfosuccinate surfactant (SDOSS) as a commonly used surfactant. The surface tension measurements at 25, 35, 45, and 55°C were used to determine of the critical micelle concentration (CMC) and surface active properties of these surfactants. The effect of the ethylene oxide (EO) unit and the alkyl chain length on the surface properties for the prepared surfactants was studied. The results show that the ethoxylated sodium monoalkyl sulfosuccinates generally have lower values of CMC than that of sodium dioctyl sulfosuccinate. The values of surface active parameters indicate that the ethoxylated sodium monooctyl sulfosuccinates and ethoxylated sodium monolauryl sulfosuccinates surfactants have adsorption properties better than the sodium dioctyl sulfosuccinate surfactant as a resulted presence of ethylene oxide in molecules of the prepared surfactants. The thermodynamic parameters show that the (EO) unites in the chemical structure of ethoxylated sodium monoalkyl sulfosuccinate surfactants improve their micellization and adsorption properties.     

Oxazoline‐Based Organocatalyst for Enantioselective Strecker Reactions: A Protocol for the Synthesis of Levamisole

A chiral oxazoline‐based organocatalyst has been found to efficiently catalyze asymmetric Strecker reactions of various aromatic and aliphatic N‐benzhydrylimines with trimethylsilyl cyanide (TMSCN) as a cyanide source at ?20 °C to give α‐aminonitriles in high yield (96 %) with excellent chiral induction (up to 98 % ee). DFT calculations have been performed to rationalize the enantioselective formation of the product with the organocatalyst in these reactions. The organocatalyst has been characterized by single‐crystal X‐ray diffraction analysis, as well as by other analytical methods. This protocol has been extended to the synthesis of the pharmaceutically important drug molecule levamisole in high yield and with high enantioselectivity.     

The Ligand‐Based Quintuple Bond‐Shortening Concept and Some of Its Limitations

Herein, the ligand‐based concept of shortening quintuple bonds and some of its limitations are reported. In dichromium–diguanidinato complexes, the length of the quintuple bond can be influenced by the substituent at the central carbon atom of the used ligand. The guanidinato ligand with a 2,6‐dimethylpiperidine backbone was found to be the optimal ligand. The reduction of its chromium(II) chloride–ate complex gave a quintuply bonded bimetallic complex with a Cr? Cr distance of 1.7056 (12) Å. Its metal–metal distance, the shortest observed in any stable compound yet, is of essentially the same length as that of the longest alkane C? C bond (1.704 (4) Å). Both molecules, the alkane and the Cr complex, are of remarkable stability. Furthermore, an unsupported Cr^I dimer with an effective bond order (EBO) of 1.25 between the two metal atoms, indicated by CASSCF/CASPT2 calculations, was isolated as a by‐product. The formation of this by‐product indicates that with a certain bulk of the guanidinato ligand, other coordination isomers become relevant. Over‐reduction takes place, and a chromium–arene sandwich complex structurally related to the classic dibenzene chromium complex was observed, even when bulkier substituents are introduced at the central carbon atom of the used guanidinato ligand.     

Ionic conductivity enhancement of PVA: carboxymethyl cellulose poly-blend electrolyte films through the doping of NaI salt

Cellulose - In this paper, we report the effect of doping sodium iodide (NaI) salt into a polymer blend matrix of sodium carboxymethyl cellulose (NaCMC) and poly(vinyl alcohol) (PVA). Solution...     

Electrochemical Biosensor Design with Multi-walled Carbon Nanotube to Display DNA-Schiff Base Interaction

This paper demonstrates a Schiff base i. e. 5-(diethylamino)-2-((2,6-diethylphenylimino)methyl)phenol (5-DDMP) that was sensed by DNA biosensor. dsDNA was immobilized onto GCE modified with functionalized multi-walled carbon nanotubes to prepare a biosensor. The efficiency of dsDNA biosensor was determined and binding of 5-DDMP with dsDNA was searched by UV-vis spectrophotometry and differential pulse voltammetry. Molecular docking simulations between 5-DDMP and dsDNA were explored and as a result, a hydrogen bond and a π-π contact were observed between 5-DDMP and deoxyguanosine base (dG22) of the strand B, deoxyadenosine base (dA5) of the strand A, respectively. These studies could be useful for new anticancer drug design and development.     

Vitamin D and Other Differentiation-promoting Agents as Neoadjuvants for Photodynamic Therapy of Cancer

The efficacy of photodynamic therapy (PDT) using aminolevulinic acid (ALA), which is preferentially taken up by cancerous cells and converted to protoporphyrin IX (PpIX), can be substantially improved by pretreating the tumor cells with vitamin D (Vit D). Vit D is one of several “differentiation-promoting agents” that can promote the preferential accumulation of PpIX within the mitochondria of neoplastic cells, making them better targets for PDT. This article provides a historical overview of how the concept of using combination agents (“neoadjuvants”) for PDT evolved, from initial discoveries about neoadjuvant effects of methotrexate and fluorouracil to later studies to determine how vitamin D and other agents actually work to augment PDT efficacy. While this review focuses mainly on skin cancer, it includes a discussion about how these concepts may be applied more broadly toward improving PDT outcomes in other types of cancer.     

Ferromagnetism and structural deformation in monolayer alpha lead oxide induced by N and F doping: New insights from first principles

We study the structural, electronic, and magnetic properties of monolayer α-PbO_0.875A_0.125 (A = N, F), which are calculated using first principles. As a result, N doping induces local ferromagnetism centered at the N²⁻ site, originating from the spin-down N 2p valence states. On the other hand, F doping induces nonmagnetism and induces ab-plane deformation, where F⁻ receives one electron to its nearest-neighboring Pb^1.75+ ions. N doping redshifts the bandgap of the undoped system and transforms it to be indirect, while F doping blueshifts the bandgap through the Burstein-Moss effect. The hybridization of Pb 6p and O 2p orbitals is stronger near the A site than that of the crystal structure edge. Our result shows new insights, predicting possible experimental results for future functional device applications.     

Numerical investigation of flame propagation in pulse detonation engine with variation of obstacle clearance

Journal of Thermal Analysis and Calorimetry - The objective of present research work is to investigate the combustion flame acceleration and performance of pulse detonation engine (PDE). The PDE...