Structure-property relationships in blends of linear low- and conventional low-density polyethylene as blown films

Three-layer coextruded blown (either blend or composite) films, made of low-density polyethylene and linear lowdensity polyethylene (1:1 ratio) of identical density, were compared. The tensile properties of both systems are nearly as high as those of the linear polyethylene while high strain rate properties including impact strength and tear resistance of the composite film are superior. Some structural insight was obtained by thermal analysis and thermoelastic measurements. Structure property relationships are discussed in light of the unique behavior, structure, and morphology of linear low-density polyethylene. The two polyethylenes are only compatible to a rather limited extent mainly affecting their blend behavior. However, a strong mutual reinforcement effect was observed.     

Simultaneous intraparticle forced convection,diffusion and reaction in a porous catalyst—II: Selectivity of sequential reactions

The selectivity of a sequence of isothermal irreversible heterogeneous reactions

within a catalytic pellet is investigated under conditions where intraparticle forced convection is a non-negligible transport mechanism. The nature of the effect of the internal filter flow depends mostly on the value of the Thiele modulus, φ₂, of the desired (middle) species. The asymptotic values of the selectivity, as φ₂ → 0 and φ₂ → ∞, are unaltered, independent of the strength of the internal flow. The intermediate region is divided into two parts. In the subregion with lower values of φ₂ the selectivity is enhanced. In the other subregion, with higher values of φ₂, the selectivity is significantly retarded to values which can be markedly below the lower asymptote. These trends are common to both poor and good selective catalysts.     

Verbal paired-associates learning in chronic schizophrenics as a function of positive and negative evaluation.

Seventy-two chronic schizophrenics (36 regressed and 36 partially remitted) and 36 normals were given paired associates of 2 levels of association strength and 2 levels of intralist response competition to learn under positive, negative, and nonevaluation conditions. Regressed schizophrenics showed maximum decrement on low-association word pairs following positive evaluation. This was especially true for those Ss with low self-esteem. These findings suggest that heightened arousal resulting from dissonance between a negative self-image and positive evaluation of performance can lead to behavioral decrement in a difficult task requiring novel associations, such decrement being congruent with the Hull-Spence behavior theory and the Yerkes-Dodson hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Annular flow of two immiscible liquids I. Mechanisms

A study was made of the flow mechanisms of two immiscible liquids with a small density difference introduced at a horizontal-pipe inlet in initial concentric flow. Extent of the annular flow, its break-up mechanisms and the subsequent flow patterns encountered were investigated with the aid of high-speed photography. Annular-flow break-up was found to occur by one of two mechanisms: collapse of the core-liquid by varicose Rayleigh-type waves or rupture of the top-wall liquid-film, attenuated by the ascent of the lighter core-liquid. Flow patterns observed after break-up involve fine dispersions, slugs or stratified layers. Charts mapping flow-pattern zones show conditions under which annular-flow holds over a considerable extent.     

On Interpretation of ESCA Spectra with Application to Thymine and Other Molecules

1s binding energies are calculated for nitrogen atoms in thymine, pyrrole, adenine, and pyridine and for carbon atoms in thymine, adenine, pyrrole, and furan, and compared with experimental values. Calculations are performed in the framework of a perturbational model using CNDO molecular wave functions. Interactions of the 1s electron with its own atom are calculated exactly whereas interactions with neighbor atoms are calculated according to two levels of approximation: (1) Point charge approximation. (2) Rigorous calculations of integrals. Magnitudes of the different interactions and integrals are analysed. The questions of assignments of ESCA shifts and the errors inherent in the calculations are discussed.     

Enhanced inactivation of E. coli bacteria using immobilized porous TiO2 photoelectrocatalysis

Immobilized TiO₂ nanotube electrodes with high surface areas were grown via electrochemical anodization in aqueous solution containing fluoride ions for photocatalysis applications. The photoelectrochemical properties of the grown immobilized TiO₂ film were studied by potentiodynamic measurements (linear sweep voltammetry), in addition to the calculation of the photocurrent response. The nanotube electrode properties were compared to mesoporous TiO₂ electrodes grown by anodization in sulfuric acid at high potentials (above the microsparking potential) and to 1 g/l P-25 TiO₂ powder. Photocatalyst films were evaluated by high resolution SEM and XRD for surface and crystallographic characterization. Finally, photoelectrocatalytic application of TiO₂ was studied via inactivation of E. coli. The use of the high surface area TiO₂ nanotubes resulted in a high photocurrent and an extremely rapid E. coli inactivation rate of ∼10⁶ CFU/ml bacteria within 10 min. The immobilized nanotube system is proven to be the most potent electrode for water purification.     

Simple iterative receivers for MIMO LP-OFDM systems

In this paper,Lp-ofdm is combined with differentMimo schemes in order to improve performance in terms of diversity gain and to exploit capacity brought by theMimo channel. The original contribution is the development of a generic iterative receiver designed forLp mimo transmission able to work whatever the antenna configuration and the spatial coding scheme. By using a globalMmse criterion, interference terms coming from space-time coding and linear precoding are jointly treated leading to a very good trade-off between performance and complexity compared to trellis based detectors particularly for high order modulations, high number of antennas and/or large size of precoding matrices.     

Mechanical properties,stress‐relaxation,and orientation of double bubble biaxially oriented polyethylene films

Biaxially oriented linear low density polyethylene (LLDPE) films were produced using the double bubble process with different machine direction (MD) orientation levels and the same transverse direction (TD) blow‐up ratio. Their mechanical behavior was characterized in terms of the tensile strength and tear resistance. The viscoelastic behavior of oriented films was studied using dynamic‐mechanical thermal analysis (DMTA). The microstructure and orientation were characterized using microscopy, X‐ray diffraction pole figures, and birefringence. The results indicate that MD ultimate tensile strength increases and the TD one decreases with MD stretching ratio. Tear propagation resistance, in general, remained mainly constant in TD and decreased in MD, as the draw ratio was increased. The morphology analyses exhibit a typical biaxial lamellar structure for all samples with different lamellar dimensions. Orientation of c‐axis in crystalline phase, molecular chain in amorphous phase along MD increased with draw ratio. In most crystals, a‐axis was located in the normal direction (ND) and the b‐axis in the ND–TD plane. A good correlation was observed between c‐axis orientation factor and MD mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3545–3553, 2006     

Conjugates of unsaturated fatty acids with propylene glycol as potentially less-irritant skin penetration enhancers

Fatty acids (FA) are well known as efficient enhancers for transdermal delivery of drugs; however, their frequent dermal toxicity limits their regular use. In order to utilize the fatty acid as a safe enhancer devoid of its irritant effect, we have synthesized and evaluated a series of fatty acids conjugated to propylene glycol (FA-PG). Each one of the conjugates was prepared as a mono- or di- acyl ester derivative. The effects of the synthetic enhancers on the porcine skin permeability were evaluated in a diffusion cell system using lidocaine as the model drug. In addition, in vivo examinations in rabbits were preformed for skin toxicological evaluation. The results indicate that among the FA-PG conjugates, oleic acid (C18:1(n-9))-PG, linoleic acid (C18:2(n-6))-PG and alpha-linolenic acid (C18:3(n-3))-PG, mono- or di-esters, enhance the penetration of lidocaine relatively to the vehicle (without enhancer). The conjugates of oleic acid (C18:1(n-9)) and linoleic acid (C18:2(n-6)) with PG have demonstrated a similar enhancing effect as the corresponding free fatty acids. Interestingly, although the mono- or the di- conjugates of alpha-linolenic acid (C18:3(n-3)) with PG enhanced the lidocaine flux as the other two fatty acid conjugates, they resulted in a reduced permeability as compared to the action of their free acid. In addition, the mono-conjugates of alpha-linolenic acid (C18:3(n-3)) with PG exhibited elevated skin irritation in rabbits (relative to the fatty acid alone) compared to the significantly reduced irritation of oleate-PG and linoeate-PG mono-conjugates. In conclusion, except saturated FA-PG and alpha-linolenic acid (C18:3(n-3)) - PG mono-conjugates, unsaturated fatty acids (e.g., oleic and linoleic acids) after conjugation to PG may be safe and effective enhancers for delivering topical drugs.