\hbox {Ph}_{3}\hbox {P/CCl}_{4} as a highly efficient reagent for one-pot N-alkylation of sulfonamides from alcohols: a rapid route to N-alkyl sulfonamides synthesis

A mild, efficient, and selective protocol for the one-pot $N$ -alkylation of sulfonamides with alcohols using triphenylphosphine and carbon tetrachloride is described. In this method, treatment of alcohols with a mixture of triphenylphosphine, carbon tetrachloride, and potassium sulfonylamide salts in refluxing anhydrous DMF furnishes the corresponding $N$ -alkyl sulfonamides in good to excellent yields. This protocol is highly efficient for various structurally diverse alcohols and potassium sulfonylamide salts. In this paper the influence of solvents and various reagents as sources for electrophilic-halogen instead of carbon tetrachloride in combination with triphenylphosphine have been examined. This protocol demonstrates the selectivity between primary and secondary alcohols. A plausible mechanism for this protocol has been described.     

A novel primary amine-based anion exchange membrane adsorber

A novel anion exchange membrane adsorber is presented which shows excellent impurity removal under different buffer conductivities ranging from 2 to 2 7mS/cm. The membrane utilizes a primary amine ligand (polyallylamine) and was designed specifically to bind impurities at high salt concentrations. Studies with DNA, endotoxin, and virus spiked into buffer at varying salt conditions were done, resulting in clearance of >3, 4, and 4 LRV, respectively, with negligible change on increasing salt up to 27 mS/cm conductivities. Verification of virus removal in mAb feedstocks is also shown. The data are compared with other membrane adsorbers and a conventional resin which utilize traditional chemistries to demonstrate improved purification performance with the primary amine ligand. Additional data on scale-up of the membrane adsorber device is discussed. A stacked flat-sheet design was implemented to ensure linear scale-up of performance using bovine serum albumin (BSA) as a model. The linearly scalable device, coupled with the highly effective membrane for virus, DNA, and endotoxin removal, represents a step forward in polishing technology for the purification of monoclonal antibodies and recombinant proteins.     

Should the AOAC use-dilution method be continued for regulatory purposes?

Despite its very poor reproducibility, AOAC INTERNATIONAL's use-dilution method (UDM) for bactericidal activity (AOAC Methods 964.02, 955.14, and 955.15) has been required by the U.S. Environmental Protection Agency (EPA) since 1953 for regulatory purposes, while methods with better reproducibility have been adopted in Canada and Australia. This study reviews UDM from a statistical perspective. Additionally, the test's expected results were compared to those obtained from actual evaluation of several formulations. Significant gaps have been identified in the reproducibility of the test data as predicted by statistical analysis and those presented to the EPA for product registration. UDM's poor reproducibility, along with its qualitative nature, requires the concentration of the active ingredient to be high enough to ensure all or most carriers to be free of any viable organisms. This is not in accord with the current trends towards sustainability, human safety, and environmental protection. It is recommended that the use of the method for regulatory purposes be phased out as soon as possible, and methods with better design and reproducibility be adopted instead.     

Setting staffing requirements for time dependent queueing networks: The case of accident and emergency departments

An incentive scheme aimed at reducing patients’ waiting times in accident and emergency departments was introduced by the UK government in 2000. It requires 98% of patients to be discharged, transferred, or admitted to inpatient care within 4 hours of arrival. Setting the minimal hour by hour medical staffing levels for achieving the government target, in the presence of complexities like time-varying demand, multiple types of patients, and resource sharing, is the subject of this paper. Building on extensive body of research on time dependent queues, we propose an iterative scheme which uses infinite server networks, the square root staffing law, and simulation to come up with a good solution. The implementation of this algorithm in a typical A&E department suggests that significant improvement on the target can be gained, even without increase in total staff hours.     

Differential pulse voltammetric simultaneous determination of noradrenalin and acetaminophen using a hematoxylin biosensor

A highly efficient noradrenalin (NA) biosensor was fabricated on the basis of hematoxylin electrodeposited on a glassy carbon electrode, GCE. The cyclic voltammetric responses of the hematoxylin biosensor at various scan rates, which were obtained in a 0.25 mmol L⁻¹ NA solution, showed the characteristic shape typical of an EC_cat process. The kinetic parameters such as electron transfer coefficient, α, the catalytic electron transfer rate constant, k′, and the standard catalytic electron transfer rate constant, k⁰, for oxidation of NA at the hematoxylin biosensor surface were estimated using cyclic and RDE voltammetry. The peaks of differential pulse voltammetric (DPV) for NA and acetaminophen (AC) oxidation at the hematoxylin biosensor surface were clearly separated from each other when they co-exited in the physiological pH (pH 7.0). It was, therefore, possible to simultaneously determine NA and AC in the samples at a hematoxylin biosensor. Linear calibration curves were obtained for 5.0 × 10⁻¹ to 65.40 μmol L⁻¹ and 65.40-274.20 μmol L⁻¹ of NA, and for 12.00-59.10 μmol L⁻¹ and 59.10-261.70 μmol L⁻¹ of AC. The sensitivities of the biosensor to NA in the absence and presence of AC were found virtually the same, which indicates the fact that the electrocatalytic oxidation processes of NA are independent of AC and, therefore, simultaneous or independent measurements of the two analytes (NA and AC) are possible without any interference. The results of 16 successive measurements show an average voltammetric peak current of 1.13 ± 0.03 μA for an electrolyte solution containing 5.00 μmol L⁻¹ NA. The hematoxylin biosensor has been satisfactorily used for the determination of NA and AC in pharmaceutical formulations. The results obtained, using the biosensor, are in very good agreement with those declared in the label of pharmaceutical inhalation products.     

The spectral method for solving systems of Volterra integral equations

This paper presents a high accurate and stable Legendre-collocation method for solving systems of Volterra integral equations (SVIEs) of the second kind. The method transforms the linear SVIEs into the associated matrix equation. In the nonlinear case, after applying our method we solve a system of nonlinear algebraic equations. Also, sufficient conditions for the existence and uniqueness of the Linear SVIEs, in which the coefficient of the main term is a singular (or nonsingular) matrix, have been formulated. Several examples are included to illustrate the efficiency and accuracy of the proposed technique and also the results are compared with the different methods. All of the numerical computations have been performed on a PC using several programs written in MAPLE 13.     

Simultaneous determination of adrenaline,uric acid,and cysteine using bifunctional electrocatalyst of ruthenium oxide nanoparticles

In this study, ruthenium oxide nanoparticles were electrochemically deposited on the surface of a glassy carbon electrode (RuON-GCE). Electrochemical studies indicate that a modified electrode (RuON-GCE) plays the role of an excellent bifunctional electrocatalyst for the oxidation of adrenaline (AD) and uric acid (UA) in two different potentials. The charge transfer coefficient (α) and the heterogeneous charge transfer rate constant (k′) between the analytes and the electrodeposited nanoparticles were determined using cyclic voltammetry experiments. Through a different pulse voltammetric (DPV) method, the plot of the electrocatalytic current versus AD and UA concentrations emerged to be constituted of two linear segments with different sensitivities. Furthermore, the detection limits of AD and UA were estimated. In DPV, RuON-GCE could separate the oxidation peak potentials of AD, UA, and cysteine (Cys) present in the same solution though, at the bare GCE, the peak potentials were indistinguishable. Finally, the modified electrode activity was studied for the electrocatalytic determination of AD in an injection solution and UA in a human urine sample. The results were found satisfactory.     

Antimicrobial Ionic Liquid-Based Materials for Biomedical Applications

Excessive and unwarranted administration of antibiotics has invigorated the evolution of multidrug-resistant microbes. There is, therefore, an urgent need for advanced active compounds. Ionic liquids with short-lived ion-pair structures are highly tunable and have diverse applications. Apart from their unique physicochemical features, the newly discovered biological activities of ionic liquids have fascinated biochemists, microbiologists, and medical scientists. In particular, their antimicrobial properties have opened new vistas in overcoming the current challenges associated with combating antibiotic-resistant pathogens. Discussions regarding ionic liquid derivatives in monomeric and polymeric forms with antimicrobial activities are presented here. The antimicrobial mechanism of ionic liquids and parameters that affect their antimicrobial activities, such as chain length, cation/anion type, cation density, and polymerization, are considered. The potential applications of ionic liquids in the biomedical arena, including regenerative medicine, biosensing, and drug/biomolecule delivery, are presented to stimulate the scientific community to further improve the antimicrobial efficacy of ionic liquids.     

Check on a nonlocal Maxwellian theory of sound propagation in fluid-saturated rigid-framed porous media

A macroscopic nonlocal theory of sound propagation in homogeneous rigid-framed porous media permeated with a viscothermal fluid has been recently proposed in this journal. It accounts for the first time for the full temporal and spatial dispersion effects, independently of the nature of the microgeometry. In this paper this new Maxwellian theory is validated in the case of sound propagation in cylindrical circular tubes, by showing that it matches exactly the long-known direct Kirchhoff–Langevin’s solutions.     

Thermodynamic and heat transfer analysis of heat recovery from engine test cell by Organic Rankine Cycle

During manufacture of engines, evaluation of engine performance is essential. This is accomplished in test cells. During the test, a significant portion of heat energy released by the fuel is wasted. In this study, in order to recover these heat losses, Organic Rankine Cycle (ORC) is recommended. The study has been conducted assuming the diesel oil to be composed of a single hydrocarbon such as C₁₂H₂₆. The composition of exhaust gases (products of combustion) have been computed (and not determined experimentally) from the stoichiometric equation representing the combustion reaction. The test cell heat losses are recovered in three separate heat exchangers (preheater, evaporator and superheater). These heat exchangers are separately designed, and the whole system is analyzed from energy and exergy viewpoints. Finally, a parametric study is performed to investigate the effect of different variables on the system performance characteristics such as the ORC net power, heat exchangers effectiveness, the first law efficiency, exergy destruction and heat transfer surfaces. The results of the study show that by utilizing ORC, heat recovery equivalent to 8.85 % of the engine power is possible. The evaporator has the highest exergy destruction rate, while the pump has the lowest among the system components. Heat transfer surfaces are calculated to be 173.6, 58.7, and 11.87 m² for the preheater, evaporator and superheater, respectively.