Moisture uptake in nanocellulose: the effects of relative humidity,temperature and degree of crystallinity

Cellulose - Foams made from cellulose nanomaterials are highly porous and possess excellent mechanical and thermal insulation properties. However, the moisture uptake and hygroscopic properties of...     

Friedel–Crafts acyl rearrangements in the fluoranthene series

Structural Chemistry - Friedel–Crafts monoacylation and diacylation of fluoranthene (FT) gave 3-acetyl-, 8-acetyl-, 3-benzoyl-, 8-benzoyl-, 3-(4-fluorobenzoyl)-, 8-(4-fluorobenzoyl)-,...     

One-pot multicomponent synthesis of some 5,6-dihydro-benzo[h]quinoline derivatives

5,6-Dihydrobenzo[h]quinoline derivatives 4a–f and 5a–c were prepared via condensation of the corresponding arylidenes 2, with 1-tetralone in the presence of ammonium acetate and sodium methoxide, respectively, following thermal, microwave and ultrasound methodologies. The yields of 4a–f were moderate when the latter two methodologies used, but the products were pure. Ultrasound and microwave irradiation methods were also used in the synthesis of 4-aryl-3-cyano-1,2,5,6-tetrahydro-benzo[h]quinoline-2-ones (6a–e) and its analogues 7a,b. The majority of compounds 4–7 were synthesized via one-pot multicomponent reactions of aldehydes, active cyanomethylene compounds, 1-tetralone and ammonium acetate. Attempts to cyclocondensation of the aminocyano derivative 4a,d with acetic anhydride in presence of conc. H₂SO₄ failed; instead the acetylamino derivative 8 was isolated. On the other hand, refluxing of 4d with formamide in DMF led to the formation of dihydrobenzo-pyrimidoquinoline 9 giving good yield. All prepared condensates were structurally elucidated by various spectroscopic methods. Screening of the potential cytotoxicity for compounds 4a–f on five cell lines, namely: colorectal carcinoma (HCT-116), Hepatocellular carcinoma (HEPG2), Human breast adenocarcinoma (MCF7), Cervix adenocarcinoma (HELA) and Glioblastoma (U251), did not show any cytotoxic activity.     

Structural studies on new copper(II) phenylhydrazoacetylacetone isonicotinoyl hydrazone complexes

Summary Copper(II) phenylhydrazoacetylacetone isonicotinoyl hydrazone complexes were prepared at two different pHs and characterized by elemental analysis and various physical techniques. In neutral solutions monoligand complexes (1) and (2) were obtained, but the bisligand complex (3) was obtained from solution at pH 10. The ligand H₂L behaved either as monobasic bidentate or dibasic tridentate towards cupric ions. Magnetic and spectral data suggest square planar structures for [CuL·H₂O]·H₂O but an octahedral structure for [Cu(HL)₂·2H₂O]·3H₂O.Author to whom all correspondence should be directed.     

Nonparametric predictive pairwise comparison for real-valued data with terminated tails

This paper presents a statistical method for comparison of two groups of real-valued data, based on nonparametric predictive inference (NPI), with the tails of the data possibly terminated, leading to small values being left-censored and large values being right-censored. Such tails termination can occur due to several reasons, including limits of detection, consideration of outliers, and specific designs of experiments. NPI is a statistical approach based on few assumptions, with inferences strongly based on data and with uncertainty quantified via lower and upper probabilities. We present NPI lower and upper probabilities for the event that the value of a future observation from one group is less than the value of a future observation from the other group, and we discuss several special cases that relate to well-known statistical problems.     

A glance on the effects of temperature on axisymmetric dynamic behavior of multiwall carbon nanotubes

In this paper the effects of temperature on theradial breathing modes(RBMs) and radial wave propagation in multiwall carbon nanotubes(MWCNTs) are investigated using a continuum model of multiple elastic isotropicshells.The van der Waals forces between tubes are simulatedas a nonlinear function of interlayer spacing of MWCNTs.The governing equations are solved using a finite elementmethod.A wide range of innermost radius-to-thickness ratioof MWCNTs is considered to enhance the investigation.Thepresented solution is verified by comparing the results withthose reported in the literature.The effects of temperature onthe van der Waals interaction coefficient between layers ofMWCNTs are examined.It is found that the variation of thevan der Waals interaction coefficient at high temperature issensible.Subsequently,variations of RBM frequencies andradial wave propagation in MWCNTs with temperatures upto 1 600 K are illustrated.It is shown that the thick MWCNTs are more sensible to temperature than the thin ones.     

Cuspidal caustic and focusing of acoustical waves generated by a parametric array onto a concave reflecting surface

The present Note is devoted to the study of the so-called cuspidal caustic at the surface of a hemi-cylindrical reflector illuminated with plane waves. In order to generate low frequency (e.g. in the range of 4 kHz) acoustical plane waves, a commercially available parametric array has been used. It produces powerful ultrasonic carrier waves at 40 kHz which can be electronically modulated between 200 Hz and 10 kHz. Further self-demodulation process during propagation in air generates an ultra-directive acoustical field (i.e. quasi-planar wavefronts) enabling to accurately study the focusing process occurring along the cuspidal caustic. The focusing coefficient can be computed locally by using two numerical tools, on one hand by computing the density of tangent rays to the caustic, and on the other hand by using some numerical results provided by a ray tracing algorithm. Some preliminary experimental data are then provided in order to validate the numerical predictions (spatial position of the caustic and focusing coefficient). To cite this article: B. Castagnède et al., C. R. Mecanique 337 (2009).     

A parametric study for improving the centrifugal pump impeller for use in viscous fluid pumping

Essentially, performance of centrifugal pumps is affected when pumping viscous fluids. In this paper a new idea is proposed to overcome the undesirable effects of viscosity on the pump performance parameters. This idea based on this matter that one specific impeller can be designed, made and installed on the pump for pumping of one fluid with specific viscosity. Therefore a specific pump can be used for pumping of different fluids with different viscosity, by replacement of pump impeller. Replacement of the impeller is more cost effective in comparison to the replacement of the whole of the pump. Passage width and outlet angle of impeller are considered as design variables and the effects of such variables investigated using experimentally validated numerical model. The H–Q, P–Q and η–Q graphs are extracted experimentally for the improved impeller, which show good improvement in comparison with original impeller.