Synergistic Interaction Between Cationic Novel Gemini Surfactant and Non-ionic Conventional Surfactants in Aqueous Medium

The interaction between novel gemini surfactant (alkane-α, ω-bis(dimethyl hexadecyl ammonium bromide) (G6)) and two different non-ionic surfactants (Triton X-114 (TX-114), Tween 20 (T-20)) has been investigated in the current study at temperature 298.15 K. The critical micelle concentration (cmc) values of mixed systems were computed by the conductometric titration in the aqueous medium. The results have been examined by utilizing numerous theoretical models (Clint, Rubingh, Motomura, Maeda, and Lange models). The experimentally determined cmc were lower than corresponding ideal values (cmc*) and decreased with the mixtures' stoichiometric mole fraction (α1) of G6. This shows non-ideal behavior between two employed components. The interaction parameter at mixed micelle (β) has been analyzed by using regular solution approximation. The attractive interaction or synergistic behavior in both mixed systems is confirmed by the negative values of β. The various energetics parameters were also evaluated and discussed.

Understanding the Molecular Dynamics of Dual Crosslinked Networks by Dielectric Spectroscopy

The combination of vulcanizing agents is an adequate strategy to develop multiple networks that consolidate the best of different systems. In this research, sulfur (S), and zinc oxide ( ZnO) were combined as vulcanizing agents in a matrix of carboxylated nitrile rubber (XNBR). The resulting dual network improved the abrasion resistance of up to ~15% compared to a pure ionically crosslinked network, and up to ~115% compared to a pure sulfur-based covalent network. Additionally, the already good chemical resistance of XNBR in non-polar fluids, such as toluene and gasoline, was further improved with a reduction of up to ~26% of the solvent uptake. A comprehensive study of the molecular dynamics was performed by means of broadband dielectric spectroscopy (BDS) to complete the existing knowledge on dual networks in XNBR. Such analysis showed that the synergistic behavior that prevails over purely ionic vulcanization networks is related to the restricted motions of rubber chain segments, as well as of the trapped chains within the ionic clusters that converts the vulcanizate into a stiffer and less solvent-penetrable material, improving abrasion resistance and chemical resistance, respectively. This combined network strategy will enable the production of elastomeric materials with improved performance and properties on demand.

Corrosion Inhibition Enhancement for Surface O&G Operations Using Nanofluids

The main objective of this study is to develop and evaluate a nanotechnology-based material in combination with a commercial corrosion inhibitor (CI) as an alternative to reduce the corrosion rate in oil and gas facilities. The corrosion rate (CR) of surface facilities coupons was estimated using weight loss analysis as the response variable in the following study, showing that in absence of CI treatments, carbon steel (CS) coupon displays corrosion rates over 2.1 mm·y−1. Four commercial CI were evaluated at concentrations ranging between 35-50 mg·L−1 to select the most suitable treatment at surface facilities conditions, showing CR reductions of around 12.2 and 22.5% in both dosages for the best CI treatment. SiO2 and Carbon Quantum Dots (CQDs) nanomaterials were added to the selected CI at nanoparticle dosages from 50 to 500 mg·L−1 to improve the behavior of the selected treatment in presence of production brine. The effectiveness of the proposed nanomaterials is strongly dependent on the nanoparticle concentration, and hence, its dispersion degree onto the metallic surface, whereas low dosages in SiO2 lead to an increase in the CR, however, low dosages in CQD lead to a reduction of the CR. The proposed NanoIC was evaluated using 1M HCl solutions to study the role of the nanoparticles in strong acid media. The corrosion rates for CS outcrops in the presence of production brine with 1M HCl was 8.6 mm·y−1, which suggests an important role of mineral acids in the corrosion phenomena. In the presence of CI at a dosage of 35 mg·L−1, the corrosion rate was reduced by 10.7%. The CR of CS surfaces treated with brine and strong acid solutions in presence of NanoCI containing CQD nanomaterials at 50 mg·L−1 shows reductions of 28.6 and 74.2%, respectively. It can be concluded, the nanoparticles act as a corrosion inhibitor agent, reducing the interaction between the acid molecules and the steel surface by the formation of a thin film. This work opens the landscape into the incorporation of carbon-based nanomaterials in surface oil and gas operations for the reduction of the corrosion rate in the facilities during the production stage in the wells by the synergistic behavior between commercial corrosion inhibitor and nanoparticles.

Water Disinfection Using Silver and Zinc Oxide Nanoparticles

Waterborne disease has changed a basic challenge in human population. recently, the use of nanotechnology and application of nanomaterials for the control of pathogens in water is widely increased in research. Common indicator for microbial quality of water are determine presence of total and fecal coliforms. The purpose of this study was to evaluate the effect of Silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs) and combination of them in removing total and fecal coliform bacteria from contaminated water. In this experimental study a synthetic solution was made by adding effluent to distilled water. In each run, the nano silver (20-100 μg /L) and ZnO NPs (0.25-2 mg/L) were added to contaminated water. The samples were tested by 15-tube series method based on the instruction 9221-B of 21th edition of standard method book on water and wastewater experiments. Bacteria removal efficiency were examined in contact times (15, 30,60, 90 and 120) minutes. Our data indicate a decrease in the number of bacteria (MPN) in the presence of the nanoparticles. Results revealed that the removal percentage of coliform bacteria removal increased with increasing the contact time and concentrations of nanoparticles. Ag NPs at a concentration of 100 μg /L and ZnO NPs at a concentration of 2 mg/L showed the highest percentage of removal bacteria and the combination of ZnO and Ag NPs have been high synergistic behavior against coliform bacteria in contaminated water. therefore, using a combination of ZnO and Ag NPs can become a new and efficient method for the removal of indicator bacteria from contaminated water.

Cellulase production by co-culture of Bacillus licheniformis and B. paralicheniformis over monocultures on microcrystalline cellulose and chicken manure-supplemented rice bran media

Single cultures and co-cultures of Bacillus licheniformis and Bacillus paralicheniformis isolated from compost were evaluated for their carboxymethyl cellulase (CMCase) and filter paperase (FPase) production potential. Using a medium supplemented with microcrystalline cellulose (MCC), in the co-culture, CMCase and FPase activities increased 8.87- and 2.28-fold and 10.15- and 3.20-fold over B. licheniformis and B. paralicheniformis monocultures, respectively. The synergistic behavior of the two isolates might be due to the consumption of hydrolysis product (glucose, cellobiose) by one or both of the isolates, which improved their metabolic performance for cellulase secretion. Optimal conditions for cellulase production by this co-culture were a temperature of 45 °C, and pH 7 at 180 rpm in a medium containing rice bran at 1% (w/v) and chicken manure as nitrogen supplement at 2% (w/v). The maximum CMCase and FPase produced under the above conditions were 79.8 U/mL and 12.5 U/mL, respectively. This corresponds to 257.4- and 59.5-fold enhancement in CMCase and FPase activity, respectively, over B. licheniformis monoculture, and 306.9- and 83.3-fold increase with respect to the B. paralicheniformis monoculture. These results indicate that improved cellulase production can be achieved through co-culture and chicken manure nitrogen-supplement.

Mixed Micellization and Spectroscopic Studies of Anti-Allergic Drug and Non-Ionic Surfactant in the Presence of Ionic Liquid

In drug delivery, surfactants are used to reduce side effects and to increase drug efficiency. The present work aimed to study the interaction of diphenhydramine hydrochloride (anti-allergic drug) with TX–45 (non-ionic surfactant) in the absence and presence of ionic liquid (1-hexyl-3-methylimidazolium chloride). The physicochemical parameters were estimated by the surface tension measurement. Various theoretical models (Clint, Rubingh, Motomura, and Maeda) were applied to determine the attractive behavior between drug and surfactant mixtures at the surface and in bulk. The drug and surfactant mixtures exhibit synergistic behavior in the absence and presence of ionic liquid. Several energetic parameters were also estimated with the assistance of regular solution approximation and pseudo phase separation model that indicate micelle formation and adsorption of surfactant at the surface is thermodynamically advantageous. The morphology of pure and mixture of amphiphiles has been estimated by the Tanford and Israelachvili theories. UV-visible spectroscopy was used to quantify the attractive behavior of the drug with surfactant with the help of a binding constant (K).

Impact of FtsZ Inhibition on the Localization of the Penicillin Binding Proteins in Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant pathogen of acute clinical importance. Combination treatment with an FtsZ inhibitor potentiates the activity of penicillin binding protein (PBP)-targeting β-lactam antibiotics against MRSA. To explore the mechanism underlying this synergistic behavior, we examined the impact of treatment with the FtsZ inhibitor TXA707 on the spatial localization of the five PBP proteins expressed in MRSA. In the absence of drug treatment, PBP1, PBP2, PBP3, and PBP4 colocalize with FtsZ at the septum, contributing to new cell wall formation. By contrast, PBP2a localizes to distinct foci along the cell periphery. Upon treatment with TXA707, septum formation becomes disrupted and FtsZ relocalizes away from mid-cell. PBP1 and PBP3 remain significantly colocalized with FtsZ, while PBP2, PBP4, and PBP2a localize away from FtsZ to specific sites along the periphery of the enlarged cells. We also examined the impact on PBP2a and PBP2 localization of treatment with β-lactam antibiotic oxacillin alone and in synergistic combination with TXA707. Significantly, PBP2a localizes to the septum in approximately 15% of the oxacillin-treated cells, a behavior that likely contributes to the β-lactam resistance of MRSA. Combination treatment with TXA707 causes both PBP2a and PBP2 to localize in malformed septal-like structures. Our collective results suggest that PBP2, PBP4, and PBP2a may function collaboratively in peripheral cell wall repair and maintenance in response to FtsZ inhibition by TXA707. Cotreatment with oxacillin, appears to reduce the availability of PBP2a to assist in this repair, thereby rendering the MRSA cells more susceptible to the β-lactam. IMPORTANCE MRSA is a multidrug-resistant bacterial pathogen of acute clinical importance, infecting many thousands of individuals globally each year. The essential cell division protein FtsZ has been identified as an appealing target for the development of new drugs to combat MRSA infections. Through synergistic actions, FtsZ-targeting agents can sensitize MRSA to antibiotics like the β-lactams that would otherwise be ineffective. This study provides key insights into the mechanism underlying this synergistic behavior as well as MRSA resistance to β-lactam drugs. The results of this work will help guide the identification and optimization of combination drug regimens that can effectively treat MRSA infections and reduce the potential for future resistance.