Acrylic-urethane/modified Rhodamine-B eco-friendly UV-curable anticounterfeiting ink

Counterfeiting is an ever-growing global problem challenging companies, governments, and customers. In recent decades, as a potential remedy, anticounterfeiting technology and information security have gained a great deal of attention from academia and industry. In this work and for the first time, Rhodamine B (RhB), an efficient and enticing fluorescent material, was modified and used as a reactive stimuli-responsive component in the formulation of an eco-friendly ink. Additionally, a UV-curable polyurethane dispersion (UCPUD) with zero volatile organic compound was synthesized and employed as the matrix for the fluorescent ink. The modified RhB and UCPUD were thoroughly characterized using Fourier-transform infrared and proton nuclear magnetic resonance analyses. Exploiting the fluorescent monomer in the ink formulations could enhance the absorption intensity (λ_max = 552 nm) of the prepared ink up to 7 with respect to its solution (λ_max = 519 nm). The printed pattern was immediately illuminated with brilliant red-pink fluorescence emission upon UV irradiation. It has been shown that the prepared fluorescent ink has potential applications in the encryption, security marking, and optical authentication of confidential cellulose substrates.     

Electrolyte effect on mixed micelle and interfacial properties of binary mixtures of cationic and nonionic surfactants

In the present work, the adsorption behavior at the liquid-air interface and micellization characteristics of mixtures of cetyltrimethylammonium bromide (CTAB) and p-(1,1,3,3-tetramethylbutyl) polyoxyethylene (TritonX-100) in aqueous media containing different concentrations of NaBr were investigated by surface tension and potentiometry measurements. From plots of surface tension (gamma) as a function of solution composition and total surfactant concentration, we determined the critical micelle concentration (CMC), minimum surface tension at the CMC (gamma(CMC)), surface excess (Gamma(max)), and mean molecular surface area (A(min)). On the basis of regular solution theory, the compositions of the adsorbed film (Z) and micelles (X(M)) were estimated, and then the interaction parameters in the micelles (beta(M)) and in the adsorbed film phase (beta(sigma)) were calculated. For all mole fraction ratios, the results showed synergistically enhanced ability to form mixed micelles as well as surface tension reduction. Furthermore beta was calculated by considering nonrandom mixing and head group size effects. It was observed that, for both the planar air/aqueous interface and micellar systems, the nonideality decreased as the amount of electrolyte in the aqueous medium was increased. This was attributed to a decrease of the surface charge density caused by increasing the concentration of bromide ions.     

Molecular interactions of cationic and anionic surfactants in mixed monolayers and aggregates

The properties of anionic-rich and cationic-rich mixtures of CTAB (cetyltrimethylammonium bromide) and SDS (sodium dodecyl sulfate) were investigated with conductometry and surface tension measurements and by determining the surfactant NMR self-diffusion coefficients. The critical aggregate concentration (CAC), surface tension reduction effectiveness(gamma(CAC)), surface excess(Gamma(max)), and mean molecular surface area (A(min)) were determined from plots of the surface tension (gamma) as a function of the total surfactant concentration. The compositions of the adsorbed films (Z) and aggregates (chi) were estimated by using regular solution theory, and then the interaction parameters in the aggregates (beta) and the adsorbed film phases (beta(sigma)) were calculated. The results showed that the synergism between the surfactants enhances the formation of mixed aggregates and reduces the surface tension. Further, the nature and strength of the interaction between the surfactants in the mixtures were obtained by calculating the values of the following parameters: the interaction parameter, beta, the size parameter, rho, and the nonrandom mixing parameter, P*. These results indicate that in ionic surfactant mixtures the optimized packing parameter has the highest value and that the size parameter can be used to account for deviations from the predictions of regular solution theory. It was concluded that, for planar air/aqueous interfaces and aggregation systems, this nonideality increases as the temperature increases. This trend is attributed to the increased dehydration of the surfactant head groups that results from increases in temperature. Further, our conductometry measurements show that the counterion binding number of mixed micelles formed in mixtures with a high CTAB content is different to those with a high SDS content. This difference is due to either their different aggregation sizes or the different interactions between the head groups and the counterions.     

Experimental Study of Pore-Scale Mechanisms of Carbonated Water Injection

Carbon dioxide (CO₂) injection is a well-established method for increasing recovery from oil reservoirs. However, poor sweep efficiency has been reported in many CO₂ injection projects due to the high mobility contrast between CO₂ and oil and water. Various injection strategies including gravity stable, WAG and SWAG have been suggested and, to some extent, applied in the field to alleviate this problem. An alternative injection strategy is carbonated water injection (CWI). In CWI, CO₂ is delivered to a much larger part of the reservoir compared to direct CO₂ injection due to a much improved sweep efficiency. In CWI, CO₂ is used efficiently and much less CO₂ is required compared to conventional CO₂ flooding, and hence the process is particularly attractive for reservoirs with limited access to large quantities of CO₂ (offshore reservoirs or reservoirs far away from inexpensive natural CO₂ resources). This article describes the results of a pore-scale study of the process of CWI by performing high-pressure visualisation flow experiments. The experimental results show that CWI, compared to unadulterated (conventional) water injection, improves oil recovery as both a secondary (before water flooding) and a tertiary (after water flooding) recovery method. The mechanisms of oil recovery by CWI include oil swelling, coalescence of the isolated oil ganglia and flow diversion due to flow restriction in some of the pores as a result of oil swelling and the resultant fluid redistribution. In this article the potential benefit of a subsequent depressurisation period on oil recovery after the CWI period is also investigated.     

Investigation of ion-pairing phenomenon in BaF2 aqueous solution: Experimental and theoretical studies

The ion-pair association constant values, related to the reaction Ba²⁺ + F⁻ ? [BaF]⁺, are determined by means of NMR spectroscopy. The values for thermodynamic functions of the ion-pairing process are calculated on the basis of the NMR results. In addition, the association entropy has been found to be dependent on temperature. Comparing the experimental data and Fuoss theory, it is found that [BaF]⁺ contact ion-pair is formed in the BaF₂ aqueous solution. Also, hydration of barium-fluoride ion-pair is investigated by the DFT method. The hydration number of barium-fluoride ion-pair is determined by comparing the experimental and theoretical results. The effect of number of water molecules on the properties of ion-pairs is investigated by determining NQR and NMR parameters. Also, the relation between the chemical shifts and the energy gap between the highest occupied molecular orbital (HOMO) and low-lying virtual molecular orbital (LUMO) is investigated.     

Elementary equivalence of rings with finitely generated additive groups

We give algebraic characterizations of elementary equivalence between rings with finitely generated additive groups. They are similar to those previously obtained for finitely generated nilpotent groups. Here, the rings are not supposed associative, commutative or unitary.     

Size‐based separations as an important discriminator in development of proximity ligation assays for protein or organism detection

Proximity ligation is a powerful technique to measure minute concentrations of target protein with high specificity, and it has been demonstrated to be effective on a wide variety of protein targets. The proximity ligation assay (PLA) technique is shown to be compromised by the amplification of a nonspecific fluorescent product that is not indicative of protein presence, which was previously unidentified in a published procedure. This result illuminates the complexity of designing the optimal PLA and the possibility of using a size‐based separation to increase the reliability of PLAs in general. Nucleic acid controls were developed to optimize the assay, which led to a novel end‐point detection method that exploits microchip electrophoresis to size the products. This method provides a greater ability to distinguish a between the target protein's signal and noise in a PLA. The utility of the PLA is demonstrated by the detection of human pathogenic Escherichia coli O157:H7 bacteria, a pathogen at the root of many recent life‐threatening food poisoning outbreaks. The results of the PLA show a detection limit of 100 E. coli O157:H7 cells with minimal cross‐reactivity with gram positive control Staphylococcus aureus bacteria. The advantages of miniaturizing this process are the 100‐fold reduction in volume, greatly reducing reagent requirements, and doubling of the thermocycling speed via noncontact infrared heating. This work, consequently, adds to the understanding of background fluorescence in PLAs, provides a method for evaluating nonspecific amplification, and shows that a qualitative PCR response indicative of the presence protein can be achieved with PLA.     

Long-term deactivation of Pt/alumina catalyst by organosilicons in the total oxidation of hydrocarbons

The deactivation of a supported platinum catalyst by long-term exposure to hexamethyldisiloxane was investigated. Ethyl acetate containing several tenfold excess of organosilicon relative to the real application was fed to the reactor. Three sets of catalyst and the blank support were aged for 350, 650, and 1000 h. The ex situ activity measurements on the aged pellets showed that all samples were deactivated as they were exposed to hexamethyldisiloxane. Silicon species were found at the surfaces of both the catalyst and the blank support. The quantitative analysis of silicon loading showed a linear profile versus poison exposure time and axial position in the bed. The radial silicon distribution in an individual pellet revealed an eggshell distribution of silicon residues, which is an indication of a diffusion-limited mechanism of silicon deposition. The deactivation was attributed to deposition of thin layer of silicon residues, which blocks the surface sites. Published in Russian in Kinetika i Kataliz, 2006, Vol. 47, No. 6, pp. 918–928. The text was submitted by the authors in English.     

Study of thermodynamic parameters in amphiphilic systems by lattice Monte Carlo: effect of tails and heads

Results from three-dimensional lattice Monte Carlo simulations of amphiphile–solvent mixtures are presented. The chemical potential is derived from the monomer distribution in different clusters rather than using a Widom particle insertion approach. The effect of tail and head characteristics on the non-ideality of these systems, aggregation number, and premicellar phenomena is considered. The aggregation number and CMC behavior of the simulated amphiphilic systems are compared with existing experimental results for non-ionic amphiphiles. Two kinds of polydispersity changing with total concentration of surfactants are observed which are related to phase transition phenomena. Shape variations in clusters are studied by calculating the eigenvalues of the gyration matrix; it is shown that large clusters are non-spherical. With the Maclaurin’s expansion of activity coefficient into volume fraction, the distribution of excess chemical potential with changing aggregation number is considered. Study of the degree of non-ideality of these amphiphiles reveals that asymmetric amphiphiles are characterized by greater non-ideality than symmetric amphiphiles. Goldstein’s parameters are calculated taking non-ideality into consideration. The difference between the phenomenological model and the simulation data is investigated.