Diverging seventh virial coefficient of sticky discs

The seventh virial coefficient of a two-dimensional system of particles interacting with a hard-core square-well pair potential is studied. The Ree-Hoover type cluster integrals were examined and it was found that a graph in the form of a hexagonal wheel with all the bonds of the attractive square-well type does not allow Baxter's ‘sticky sphere’ limit to be achieved. The value of that particular cluster integral was calculated. It was shown that when approaching the sticky limit the cluster integral corresponding to the hexagonal wheel diverges linearly with the height of the peak in the Mayer f function at the location of the potential square-well. As a consequence, the seventh virial coefficient of the sticky disc system does not have a finite value.     

The numerical solution of the BGYB equation for the liquid-vapour interface

The derivation of the Born-Green-Yvon-Bogolyubov integrodifferential equation is discussed. As the numerical solution of this equation is very sensitive to the approximations it is pointed out that qualitative differences between the density profiles obtained with different approximations can be expected. The connection between the predictions of linear response theory and the behaviour of the resulting density profiles is also indicated.     

Application of Soczewiński-type equation to study molecular interactions in liquid adsorption chromatography

Summary The possible application of the Soczewiński-type linear relationship is considered for the estimation of molecular interactions in chromatographic systems. The physical meaning of the slope of this relationship is discussed. The influence of solvent adsorption, solvent-solvent and solute-solvent interactions on the slope are shown. Theoretical conceptions are verified for several solutes and five binary mixed mobile phases.     

Standardized Characterization of Electrocatalytic Electrodes

This paper investigates the utility of ‘cross–lab’ comparative analysis of electrocatalytic electrode performance using standardized modular stack cells and test protocols. Using poly(methylene green)‐modified glassy carbon electrodes as the model system, we characterized electrode fabrication and performance with respect to the catalytic oxidation of NADH at neutral pH and low overpotential. Three sets of experiments were duplicated across four independent laboratories and the experimental results from each set were analyzed and compared in terms of key electroanalytical parameters. Statistical analyses were performed at three distinct levels: 1) the standard deviation among repetitive cycles within an experiment; 2) the standard deviation among repetitive experiments in the same laboratory, and 3) the standard deviation among experiments performed across all four laboratories. Using predefined criteria of ‘reproducibility’ for each level, most parameters were found to be statistically reproducible at most levels. When a particular parameter was found to be irreproducible in a given level, commentary is given on how that information can be used diagnose what chemical/physical aspects of the process were uncontrolled or poorly understood and therefore candidates for future research. This exercise, which is presented as a ‘proof–of‐principle’ step towards the concept of standardizing electrocatalytic evaluation, illustrates the importance of executing electrochemical characterization protocols across several labs and using fixed geometry and dimensions, system configuration, and applied electrochemical conditions. Future work is under way to extend these principles to systems with fluid flow.     

Electrochemical Detection of Phenol Removal by Using a Biosorbent Originated Factory Solid Waste

Biosorption is a preferable method for phenol (PNL) removal from water sources using a cheap and eco-friendly biomass. The combination of the biosorption technique with practical, affordable, sensitive, and selective monitoring tools gives a new perspective to environmental monitoring applications. Herein, as the first time, the monitoring of PNL biosorption performed using a factory waste was done by pencil graphite electrodes (PGEs) and cyclic voltammetry (CV) technique. The monitoring of the biosorption process was completed with reproducible and reliable results in just 40s. The biosorption was achieved in different water samples and the presence of different phenolic compounds.     

Kinetics of Chain Exchange between Diblock Copolymer Micelles

Dissipative particle dynamics simulation is employed to study the chain exchange kinetics between micelles of diblock copolymer in aqueous solution via in silico hybridization method. One focus is placed on the effect of chain flexibility on the dynamic behavior by varying the spring constant in the bead‐spring model. The length ratio of hydrophilic to hydrophobic block is also varied. It is found that chain expulsion/insertion is the dominant mechanism in the chain exchange process. The most interesting finding is the multimodal relaxation behavior for the chain exchange and expulsion when the spring constant is small or the length ratio of hydrophilic to hydrophobic block is large. This phenomenon is due to an increase in size polydispersity of micelles with rising population of small aggregates/micelles, for which the exchange kinetics is faster. Micelles with larger aggregation numbers (>10) are found to follow single exponential relaxation kinetics.

     

Skin friction pattern analysis using near-wall PIV

A near-wall PIV technique is introduced to analyze skin friction patterns around a wall-mounted cube. The closest 2-D PIV measurements were performed within 0.5 mm of plane surfaces (with a 1 mm thick laser sheet). A comparison with oil-flow visualizations clearly shows the influence of the measurement height. The differences between both techniques are analyzed and classified into two categories: positioning discrepancies (discrepancies between PIV and oil-flow critical points’ positions), and structural differences (i.e., topological differences). Both types are analyzed. The advantages of this technique in the perspective of a 3-D separated flow topology analysis is twofold. Firstly, it requires standard 2-D PIV equipment, acceptable calibration and setup time. Secondly, it provides reliable qualitative and quantitative near-wall data in areas where oil-flow visualizations are inefficient and with a spatial resolution that would otherwise require many sensors.     

Spatio-temporal structure and cycle to cycle variations of an in-cylinder tumbling flow

The aim of this paper is to make use of PIV and high-speed PIV in a research engine of moderate tumbling ratio in order to analyze both the spatial structure of the flow and its temporal evolution during series of consecutive cycles. Appropriate analyzing tools are introduced, and four different points are addressed: (1) the chain of events driving the generation of the three-dimensional mean tumbling motion is investigated; (2) a Lagrangian analysis of the roll-up of the tumbling jet in individual cycles demonstrates a strong cycle to cycle variation during the compression phase (the rms of the position of the jet front being approximately 10% of the piston stroke); (3) focussing on the “breakdown” phase, phase invariant proper orthogonal decomposition enables us to distinguish cycles according to their structure near top dead center (TDC). We show that when the coherent energy of the flow is conserved, there is no increase in the fluctuating kinetic energy; (4) finally, the phase-averaged Reynolds stresses is decomposed into a contribution of the in-cycle coherence and the turbulence carried by the flow states. Approximately 30% of the fluctuating kinetic energy is due to cycle to cycle fluctuations in this chamber near TDC.     

Efficient zinc initiators supported by NNO‐tridentate ketiminate ligands for cyclic esters polymerization

A series of zinc benzylalkoxide complexes, [LⁿZn(μ‐OBn)]₂ (L = L ¹ H – L ⁵ H ), supported by NNO‐tridentate ketiminate ligands with various electron withdrawing‐donating subsituents have been synthesized and characterized. X‐ray crystal structural studies revealed that complexes 2b and 4b are dinuclear bridging through the benzylalkoxy oxygen atoms with penta‐coordinated metal centers. All the metal complexes have acted as efficient initiators for the ring‐opening polymerization of L ‐lactide (within 12 min, 0 °C). Remarkably, a molecular weight of PLLA up to 580,000 can be achieved using [(L⁵Zn(μ‐OBn)]₂ ( 5b ) as an initiator. The kinetic studies for the polymerization of L ‐lactide with complex 3b at ?10 °C corresponded to first‐order reactions in the monomer. The ring‐opening polymerization (ROP) of ε‐caprolactone, ε‐decalactone, β‐butyrolactone and their copolymer with complex 3b was investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Diffraction patterns for a transmission volume hologram under Bragg mismatch

We have presented simulations and experiments for 2-dimensional diffraction distributions of a transmission volume hologram. We sample the input pattern with a few elementary points and calculate the diffraction of the corresponding elementary grating. The simulations can describe well the diffraction pattern obtained in the experiment and can be used to predict the tolerance for angular deviation of the reading beam. The tolerance for angular deviation depends on its direction. It is affected by the Bragg degeneracy. The simulation results provide a clear picture of the spatial tolerance for reading a transmission volume hologram.