Thermal conductivity enhancement of copper–diamond composites by sintering with chromium additive

The thermal diffusivity (TD) and thermal conductivity (TC) of Cu–Cr–diamond composite materials were examined in the temperature range from 50 to 300 °C for diamond volume fractions of 22, 40, 50, 55, and 60 %. The samples were fabricated by the plasma pulse sintering (PPS) method. TC does not increase proportionally with the diamond fraction in the particular composite materials. The highest TD was determined for 50 % diamond volume fraction, and the evaluated TC reached 658 W m^?1 K^?1 at 50 °C. This article complements earlier articles concerning synthesis and characterization of the diamond–copper composites produced by the PPS method.     

Oxofunctionalized Trans-2-carboxycinnamic Acids by Catalytic Domino Oxidation of Naphthols and Hydronaphthoquinones

The catalytic oxidation of naphthalenes was investigated. Hydrogen peroxide (30% aqueous) was used as an oxygen source, and 2,2’-dinitro-4,4’-ditrifluoromethyldiphenyl diselenide was the oxygen-transfer catalyst. Unsubstituted naphthols produce trans-2-carboxycinnamic acid in nearly quantitative yields. Both naphthols bearing substituents on the conjugated ring deliver corresponding trans-2-carboxycinnamic acids in good to excellent yields. The 1,7- and 2,6-hydronaphthoquinones, substituted by carboxy and carboxymethyl groups, produce hydroxycinnamic acids in satisfactory to excellent yields. A catalytic domino reaction mechanism is proposed.     

An extension of Bar-Hen's preliminary test procedure

An asymptotic test procedure, proposed by Bar-Hen (J. Multivariate Anal. 57 (1996) 266), for deciding if a given set of data represents a new population or one of k a priori known populations, is extended to the case when the new population is described by more than one parameter.     

Verification of mathematical formulae applied to overhead stage canopy design

This paper presents a comparison of the experimental research concerning overhead stage canopies with a numerical approach based on selected mathematical models. The numerical predictions are made using the simplified asymptotic curves suggested by Rindel and modified by Skålevik. For singular cases a prediction with detailed calculations based on the Fresnel–Kirchhoff approximation is also given. The aim of the work is to verify proposed algorithms for designing reflective panels as well as to determine the conditions of conducting such procedures. It is shown that based on Rindel’s approximation one may determine some substantial information about sound reflection from the panels i.e. the value of upper limit frequency as well as the relative sound reflection level. On the other hand, the lower cut-off frequency should be calculated using Skålevik’s model as the value obtained from Rindel’s formula is undervalued. Such an approach could be applied to design reflective structures. However, it has some limitations for example for arrays of perturbed symmetry or sparse arrays as well as in the case of non-perpendicular angles of sound wave incidence. Then it may be necessary to apply more accurate numerical models.     

Enantioselective 1,3‐dipolar cycloaddition reactions using complexes of (−)‐sparteine

Regio‐ and stereoselective 1,3‐dipolar cycloaddition of nitrile oxides to internal 2‐pentenols and α,β‐unsaturated esters catalyzed by (?) sparteine‐lanthanide complexes affords corresponding 3‐aryl‐2‐isoxazolines with enantioselectivities up to 68% ee.     

Polymer–Graphene Nanocomposite Materials for Electrochemical Biosensing

Biosensing is an important and rapidly developing field, with numerous potential applications in health care, food processing, and environmental control. Polymer–graphene nanocomposites aim to leverage the unique, attractive properties of graphene by combining them with those of a polymer matrix. Molecular imprinted polymers, in particular, offer the promise of artificial biorecognition elements. A variety of polymers, including intrinsically conducting polymers (polyaniline, polypyrrole), bio‐based polymers (chitosan, polycatechols), and polycationic polymers (poly(diallyldimethylammonium chloride), polyethyleneimine), have been utilized as matrices for graphene‐based nanofillers, yielding sensitive biosensors for various biomolecules, such as proteins, nucleic acids, and small molecules.

     

Numerical analysis of nitrogen adsorption isotherms on active carbons by an employment of the new LBET class models

The reported research concerns properties of the new LBET class models designed to describe the heterogeneous adsorption on microporous carbonaceous materials. In particular, the new adsorption models were used for the analysis of the microporous structure of two active carbons on the basis of nitrogen adsorption isotherms. This paper gives more information on the properties of the proposed identification technique.     

Comment on: ‘‘The effect of pressure on morphological features and quality of synthesized graphene’’ [Res Chem Intermed journal DOI 10.1007/s11164-016-2594-8]

In their recent article, Alipour et al. (Res Chem Intermed, 1. doi: 10.1007/s11164-016-2594-8) studied the effect of pressure on the morphological characteristics and quality of synthesized graphene from SEM data. Here, the basics of fractal calculations and depth histogram will be explained to avoid such egregious mistakes between using AFM, SEM and stereo SEM images by authors.     

Characterization of Mint Essential Oils by High-performance Liquid Chromatography and Chemometrics

The raw material from Mentha piperita L, M. arvensis L, M. longifolia L, M. spicata, and M. suaveolens from various locations were extracted using steam distillation to obtain the mint essential oils. High-performance liquid chromatography was used to obtain fingerprints of the mint samples. SpecAlign, Savitzky–Golay, recursive alignment by fast Fourier transform, Pearson’s correlation coefficient, and principal component analysis were used to characterize the chromatograms. The results were used to confirm the similarities of M. longifolia collected in Ostrowsko, Poland in 2013 and 2014. The considerable similarity of these M. longifolia samples demonstrates that the reported chemometric approach is suitable for the classification of plant materials.