Zone conditional analysis of a freely propagating one-dimensional turbulent premixed flame

The zone conditional conservation equations are derived and validated against the DNS data of a freely propagating one-dimensional turbulent premixed flame. Conditional flow velocities are calculated by the conditional continuity and momentum equations, and a modeled transport equation for the Reynolds average reaction progress variable. An asymptotic formula for turbulent burning velocity is obtained with the effects of a finite Damköhler number accounted for as an additional factor. It is shown that flame generated turbulence is primarily due to correlations between fluctuating gas velocities and fluctuating unit normal vector on a flame surface. More investigation is required to validate general predictive capability of the derived conditional conservation equations and the relationships modeled for closure.     

Likelihood-Based Local Polynomial Fitting for Single-Index Models

The parametric generalized linear model assumes that the conditional distribution of a response Y given a d-dimensional covariate X belongs to an exponential family and that a known transformation of the regression function is linear in X. In this paper we relax the latter assumption by considering a nonparametric function of the linear combination β^TX, say η₀(β^TX). To estimate the coefficient vector β and the nonparametric component η₀ we consider local polynomial fits based on kernel weighted conditional likelihoods. We then obtain an estimator of the regression function by simply replacing β and η₀ in η₀(β^TX) by these estimators. We derive the asymptotic distributions of these estimators and give the results of some numerical experiments.     

Three-dimensional stable nonconforming parallelepiped elements for the Stokes problem

Stability result is obtained for the approximation of the stationary Stokes problem with nonconforming elements proposed by Jim Douglas Jr. et al. [Math. Model. Numer. Anal. 33 (4) (1999) 747] for the velocity with conforming bubble functions and discontinuous piecewise linear for the pressure on parallelepiped elements. Optimal order H¹ and L² error estimates are derived.     

Evolutionary screening of biomimetic coatings for selective detection of explosives

Susceptibility of chemical sensors to false positive signals remains a common drawback due to insufficient sensor coating selectivity. By mimicking biology, we have demonstrated the use of sequence-specific biopolymers to generate highly selective receptors for trinitrotoluene and 2,4-dinitrotoluene. Using mutational analysis, we show that the identified binding peptides recognize the target substrate through multivalent binding with key side chain amino acid elements. Additionally, our peptide-based receptors embedded in a hydrogel show selective binding to target molecules in the gas phase. These experiments demonstrate the technique of receptor screening in liquid to be translated to selective gas-phase target binding, potentially impacting the design of a new class of sensor coatings.     

Preparation of orthogonally functionalized surface using micromolding in capillaries technique for the control of cellular adhesion

This study presents a simple method for the fabrication of an orthogonal surface that can be applied for cell patterning without the need to immobilize specific adhesive peptides, proteins, or extracellular matrix (ECM) for cell attachment. Micromolding in capillaries (MIMIC) produced two distinctive regions. One region contained poly(ethylene glycol)–poly(d,l-lactide) diblock copolymer (PEG–PLA) designed to provide a biological barrier to the nonspecific binding of proteins and fibroblast cells. The other region was coated with polyelectrolyte (PEL) to promote the adhesion of biomolecules including proteins and cells. Resistance to the adsorption of proteins increased with the length of PEG and PLA chains because the longer PEG chain increased the PEG layer thickness and the longer PLA chain induced stronger interaction with the PEL surface. The PEG5k–PLA2.5k (20 mg/ml) was the most efficient candidate for the prevention of protein adhesion among the PEG–PLA copolymers examined. The orthogonal functionality of prepared surfaces having PEL regions and background PEG–PLA regions resulted in rapid patterning of biomolecules. Fluorescein isothiocyanate-tagged bovine serum albumin (FITC-BSA) and fibroblast cells successfully adhered to the exposed PEL surfaces. Although methods for cell patterning generally require an adhesive protein layer on the desired area, these fabricated surfaces without adhesive proteins provide a gentle microenvironment for cells. In addition, our proposed approach could easily control patterns, sizes, and shapes at micron scale.     

Synthesis of water soluble PEGylated magnetic complexes using mPEG-fatty acid for biomedical applications

We report the successful fabrication of the various types of water soluble PEGylated magnetic complexes (PMCs) for magnetism-related biomedical applications. Various types of PMCs were synthesized and tested to accomplish phase transfer from organic to aqueous phase using monomethoxy polyethylene glycol (mPEG)-fatty acid amphiphilic block copolymers (PFs) through conjugation of the hydroxyl group of mPEG with the carboxyl group of fatty acids. We also carefully investigate their colloidal stabilities in aqueous phase according to the ratio of hydrophilic and hydrophobic lengths relying on different types of fatty acids. Synthesized PMCs clearly demonstrated high magnetic sensitivity under magnetic field as magnetic resonance (MR) contrast agents. Furthermore, PMCs exhibited sufficient cell viabilities and excellent cell affinities in an in vitro model. Our results demonstrated that our PMCs possessed the potential for highly efficient magnetism-related biomedical applications such as MR image agents, drug delivery and tracking of cells.     

From homogeneous to heterogeneous nucleation of chain molecules under nanoscopic cylindrical confinement

The crystallization of monodisperse linear polyethylene confined in nanoporous alumina is investigated with the calorimetric measurements. We observe a drastic change in crystallization behavior, specifically nucleation, with a decrease in the pore diameter. Crystallization in relatively larger pores with the diameters of 62 and 110 nm occurs at lower temperatures within a very narrow range, whereas crystallization in smaller pores with diameters of 15-48 nm occurs at a higher and broad range of temperatures. Nucleation and crystallization kinetics in nanopores is discussed based on classical nucleation theory as well as the Avrami theory.