Numerical simulations of the ignition of n-heptane droplets in the transition diameter range from heterogeneous to homogeneous ignition

Spontaneous ignition of single n-heptane droplets in a constant volume filled with air is numerically simulated with the spherical symmetry. The volume is closed against mass, species, and energy transfer. The numerical model is fully transient. It continues calculation even after the droplet has completely vaporized, and therefore can predict pre-vaporized ignition. Initial pressure and initial air temperature are fixed at 3 MPa and 773 K, respectively. The droplet is initially at room temperature, and its diameter is between 1 and 100 μm. When the overall equivalence ratio is fixed to be sufficiently large, there exists no ignition limit in terms of initial droplet diameter d₀, and the ignition delay takes a minimum value at certain d₀. In such a case, transition from the heterogeneous ignition to the homogeneous ignition with decreasing d₀ is observed. When d₀ is fixed to be so small that the ignition would not occur in an infinite volume of air, the ignition delay takes a minimum value at certain , which is less than unity. Two-stage ignition behavior is investigated with this model. Ignition delay of a cool flame has the dependence on d₀ that is similar to that of ignition delay of a hot flame when is unity. When is almost zero, the ignition limit for cool flame in terms of d₀ is not identified unlike that for hot flame.     

Synthesis and properties of polyimide ionomers containing sulfoalkoxy and fluorenyl groups

A series of sulfopropylated and sulfobutylated polyimide copolymers containing fluorenyl groups, SPI‐4, were synthesized to investigate the effect of alkyl side chains on the properties (stability, mechanical strength, water uptake, and proton conductivity) of the polymimide electrolyte membranes. SPI‐4 showed much better hydrolytic stability (in 10% MeOH aq at 100 °C) than the main chain sulfonated polyimide, SPI‐1. Tough, flexible, and ductile membranes were obtained from these copolymers. At high relative humidity all the SPI‐4 membranes showed high mechanical properties (>34 MPa of the maximum stress) and proton conductivity (>0.1 Scm^?1). These properties are comparable to or even better than those of the perfluorosulfonic acid ionomer (Nafion 112). The new polyimide ionomers have proved to be a possible candidate as polymer electrolyte membrane for PEFCs and DMFCs. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4439–4445, 2005     

Transport of calcium and potassium ions in opposite directions in a liquid membrane system

A new type of 18-crown-6 derivative having two carboxylic acids on the side arms transported calcium and potassium ions in opposite directions across a dichloromethane membrane by pH control. Calcium and potassium ions were concentrated in the acidic and the basic phases, respectively. The presence of picrate ion in the acidic phase plays an important role in the transport of potassium ion from the acidic to the basic phase.     

Ionic products in ground polymer. IV. Anions in poly(vinylidene fluoride)

When poly(vinylidene fluoride) (PVDF) was ground with tetracyanoethylene (TCNE) powder in a vibration glass ball mill in vacuum in the dark at 77 K, the TCNE anion radical (TCNE-) was detected in the mixture by ESR spectroscopy. The TCNE.- is formed by the abstraction of electrons by TCNE from the anion that is produced by a heterogeneous bond scission of carbon-carbon bonds in the polymer main chain. The assignment of TCNE.- was carried out by the ESR spectral simulation on the basis of an anisotropic effective hyperfine tensor that includes a forbidden transition term. At least 85% of the bond scission of the PVDF main chain is induced by a heterogeneous process to produce ionic products. The yield of these mechanions seems to increase with the polarity of carbon-carbon bond owing to a substituent group bonded to the carbon in the polymer main chain.     

Solvable lattice models related to the vector representation of classical simple Lie algebras

A series of solvable lattice models with face interaction are introduced on the basis of the affine Lie algebraX _n ⁽¹⁾ =A _n ⁽¹⁾ ,B _n ⁽¹⁾ ,C _n ⁽¹⁾ ,D _n ⁽¹⁾ . The local states taken on by the fluctuation variables are the dominant integral weights ofX _n ⁽¹⁾ of a fixed level. Adjacent local states are subject to a condition related to the vector representation ofX _n . The Boltzmann weights are parametrized by elliptic theta functions and solve the star-triangle relation.     

Syntheses of polymerizable hydroquinone derivatives

Several polymerizable hydroquinone derivatives were prepared by the Williamson synthesis. Thus, hydroquinone mono(p-vinylbenzyl) ether (III-1), hydroquinone methyl p-vinylbenzyl ether (III-4), and hydroquinone benzyl p-vinylbenzyl ether (III-5), tert-butylhydroquinone mono(p-vinylbenzyl) ether (III-2), and 2,5-di-tert-butylhydroquinone mono(p-vinylbenzyl) ether (III-3) were synthesized by the reactions of p-chloromethylstyrene with the corresponding hydroquinone derivatives in alcoholic potassium hydroxide or with their potassium salts in dipolar aprotic solvents. All monomers were found to polymerize by free-radical initiation except III-3, which required a cationic initiator.     

Surface-enhanced raman spectra and molecular orientation of phthalazine adsorbed on a silver electrode

SERS from phthalazine adsorbed on an Ag electrode was investigated under several conditions of applied voltage and solution concentration. Spectral assignments of the Raman bands were successfully performed and two differently oriented adsorbates, i.e. flat and end-on species, were identified. The contribution of the image field to the SERS intensity was considerable.     

TheA n /(1) face models

Presented here is the construction of solvable two-dimensional lattice models associated with the affine Lie algebraA _n ^/(1) and an arbitrary pair of Young diagrams. The models comprise two kinds of fluctuation variables; one lives on the sites and takes on dominant integral weights of a fixed level, the other lives on edges and assumes the weights of the representations ofsl(n+1, C) specified by Young diagrams. The Boltzmann weights are elliptic solutions of the Yang-Baxter equation. Some conjectures on the one point functions are put forth.     

Quantum dots-based reverse phase protein microarray

CdSe nanocrystals, also called quantum dots (Qdots) are a novel class of fluorophores, which have a diameter of a few nanometers and possess high quantum yield, tunable emission wavelength and photostability. They are an attractive alternative to conventional fluorescent dyes. Quantum dots can be silanized to be soluble in aqueous solution under biological conditions, and thus be used in bio-detection. In this study, we established a novel Qdot-based technology platform that can perform accurate and reproducible quantification of protein concentration in a crude cell lysate background. Protein lysates have been spiked with a target protein, and a dilution series of the cell lysate with a dynamic range of three orders of magnitude has been used for this proof-of-concept study. The dilution series has been spotted in microarray format, and protein detection has been achieved with a sensitivity that is at least comparable to standard commercial assays, which are based on horseradish peroxidase (HRP)-catalyzed diaminobenzidine (DAB) chromogenesis. The data obtained through the Qdot method has shown a close linear correlation between relative fluorescence unit and relative protein concentration. The Qdot results are in almost complete agreement with data we obtained with the well-established HRP-DAB colorimetric array (R² = 0.986). This suggests that Qdots can be used for protein quantification in microarray format, using the platform presented here.