Pyrolysis-GC-MS reveals important differences in hydrolytic degradation process of wood flour and rice bran filled polylactide composites

Pyrolysis-GC-MS of polylactide (PLA) biocomposites before and after hydrolytic degradation revealed prominent differences in the hydrolytic degradation process of rice bran and wood flour filled biocomposites. The water uptake and mass loss for polylactide/wood flour composites were similar to that of plain PLA. Pyrolysis-GC-MS, however, showed that on prolonged ageing the hydrolysis of PLA led to increased wood flour concentration in the remaining biocomposite matrices. In contrast, the polylactide/rice bran composites exhibited larger water uptake and higher mass loss. Pyrolysis-GC-MS and FTIR analysis proved that the higher mass loss was caused by migration of rice bran from the composites. The type of natural filler could thus greatly influence the degradation process and/or the stability of the materials in aqueous or humid environments.     

Modular equations and distortion functions

Modular equations occur in number theory, but it is less known that such equations also occur in the study of deformation properties of quasiconformal mappings. The authors study two important plane quasiconformal distortion functions, obtaining monotonicity and convexity properties, and finding sharp bounds for them. Applications are provided that relate to the quasiconformal Schwarz Lemma and to Schottky’s Theorem. These results also yield new bounds for singular values of complete elliptic integrals.      

On Belinskii conformality in countable sets of points

The local behavior of plane quasiconformal mappings is investigated. In particular, generalizing the well-known Reich-Walczak problem, we study the possibility for a quasiconformal mapping to be conformal in the sense of Belinskii at a prescribed point or in a prescribed set of points when the modulus of the complex dilatation is a fixed measurable function. The notion of the Belinskii conformality is related to the conception of asymptotical rotations by Brakalova and Jenkins.

     

Stable Isotopically-Enriched D-Glucose: Strategies to Introduce Carbon,Hydrogen and Oxygen Isotopes at Various Sites

INTRODUCTION

For many years stable isotopes were confined to the chemical laboratory, where they were used primarily to study reaction rates,¹ reaction mechanisms,² and molecular conformation.^3,4 Recently, stable isotopically-enriched molecules have been playing increasing roles in biochemical studies, particularly as probes of in vitro biological metabolism^5,6 and of biomacromolecular structure.^7,8 These modern applications have been stimulated, in large part, by dramatic technical developments in nuclear magnetic resonance (NMR) spectroscopy⁹ and mass spectrometry (MS).¹⁰ Very-high field multinuclear high-resolution NMR in one-, two- and three- dimensions,^11,12 and various volume-selective forms of NMR derived from topical magnetic resonance (TMR) spectroscopy,¹³ have become important analytical methods in the study of biological phenomena. TMR and related techniques such as ISIS (Image Selected In-Vivo Spectroscopy)¹⁴ and Spatially Resolved Spectroscopy (SPARS)¹⁵ are particularly attractive, as they permit high-resolution, volume-specific observations essential to non-invasive metabolic studies of intact organs and organisms. Magnetic resonance imaging (MRI)¹⁶ is now a standard clinical tool for non-invasive diagnosis of disease, especially cancer, in humans. Clinical MRI is confined currently to the observation of water protons in cells, but will likely become multinuclear (e.g., ⁷Li, ¹⁹F, ²³Na, ³¹P, ¹³C) in the future.¹⁷     

Estimates for conformal capacity

Let a,b,c,d be distinct points on \overline \bf R ⁿ . By p we denote the minimal conformal capacity of all rings (E,F) with a,b ∈ E and c,d∈ F . For n=2 , we use explicit expressions of p in terms of complete elliptic integrals to prove a sharp inequality that connects p and the conformal capacity of Teichmüller's ring. We also show, by a concrete example, how we can use techniques involving polarization and hyperbolic geometry to prove estimates for the conformal capacity of rings. November 16, 1998. Date revised: March 2, 1999. Date accepted: May 7, 1999.     

Elliott's identity and hypergeometric functions

Elliott's identity involving the Gaussian hypergeometric series contains, as a special case, the classical Legendre identity for complete elliptic integrals. The aim of this paper is to derive a differentiation formula for an expression involving the Gaussian hypergeometric series, which, for appropriate values of the parameters, implies Elliott's identity and which also leads to concavity/convexity properties of certain related functions. We also show that Elliott's identity is equivalent to a formula of Ramanujan on the differentiation of quotients of hypergeometric functions. Applying these results we obtain a number of identities associated with the Legendre functions of the first and the second kinds, respectively.     

Effect of Droplet Size and Atomization on Spray Formation: A Priori Study Using Large-Eddy Simulation

The paper is mainly focused to the vast number of researchers who work within direct injection (DI) engine fuel spray simulations. The most common simulation framework today within the community is the Reynolds Averaged Navier Stokes (RANS) approach together with the Lagrangian Particle Tracking (LPT) method. In fact, this study is one of the first studies where high resolution LES/LPT diesel spray modeling is considered. The potential of LES to deepen the present day multidimensional LPT fuel spray simulations is discussed. Spray evolution is studied far from an injector by modeling a spray as a particle laden jet (PLJ). The effect of d on mixing in non-atomizing and atomizing sprays is thoroughly investigated at jet inlet Reynolds number Re?=?10⁴ and Mach number Ma?=?0.3. Based on and justified by rather recent and also quite old ideas, novel and compact views on droplet breakup in turbulent flows are pointed out from the literature. We use LES/LPT to illustrate that even in a low Weber number flow (We?<?13) the droplet breakup modeling may need considerable attention in contrast to what is typically assumed in the present-day breakup models. LES and LPT techniques are first applied to essentially confirm certain expected droplet size effects on spray shape in non-atomizing monodisperse sprays. In the simulations LES e.g. produces an expected turbulent dispersion pattern that depends on droplet diameter (d) without a droplet dispersion model in contrast to RANS. A new compact droplet breakup model is formulated and tested for droplets that break with a natural resonance time rate according to the Poisson process. As a result of the study: 1) the analysis gives a rigorous and enriching proof of currently existing views on droplet size effects on mixing, and 2) the presented a priori analysis points out the importance of modeling the resonance breakup even at a low We.