Prediction of the surface tension of surfactant mixtures for detergent formulation using Design Expert software

Abstract  

The formulation of a detergent product is a complicated task which depends on many economical, ecological, and practical parameters. The goal is to achieve a product which will have optimal washing properties and significantly decrease the surface tension. Therefore, prediction of the minimal surface tension of a mixture of four different surfactants can be very beneficial for the industry. In this work this task was performed by using Stat-Ease Design Expert software. This program was successfully applied for prediction of the minimal surface tension and optimization of the composition of different surfactant mixtures. Predicted data were compared with experimental results, and very good correlation was achieved. For further application, more complex optimization procedures could be performed by adding additional parameters to the Design Expert software. Therefore, this program is extremely useful for the laundry industry and could be successfully applied in many other, more complex tasks.     

Schur‐convexity and quadrature formulae

This paper aims to contribute to the exploration of quadrature formulae by proving that the error of a quadrature formula has the Schur‐convexity property. The emphasis is on the quadrature formulae with the maximum degree of precision. The Schur‐convexity of the error has an interesting implication – the monotonicity of the error. Namely, it turns out that the absolute value of the error is always smaller on a smaller interval (of the two which share the same midpoint).     

Circular Dichroism of Some 2-(Phenylmethyl)pyridine Derivatives

The absolute configuration of the 2-(phenylmethyl)pyridine derivatives 1 – 9 had been established by X-ray diffraction and chemical correlation. Their CD spectra have been studied in different solvents for the free and protonated forms. It has now been found that, from the sign of the strong CD couplet between 270 and 220 nm, which was observable for all these compounds besides 7 and 9 , their absolute configuration can be determined much quicker.     

A Particulate Biochromatographic Support for the Research of Arginase Inhibitors Doped with Nanomaterials: Differences Observed Between Carbon and Boron Nitride Nanotubes. Application to Three Plant Extracts

The arginase enzyme was bound to porous silica using a reactive polymer where two types of nanomaterials were entrapped, i.e., carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs). For the first time, it was shown that BNNTs were highly efficient for increasing the performance of a particulate bioactive support. Also, we demonstrated that BNNTs enhanced more strongly this effect in comparison with CNTs. In addition, with this novel bioactive support, the relative IC50 values of the well-known arginase inhibitors were found to be in agreement with those derived by the conventional spectrometric method. It was shown the ethylacetate extract of the roots of Spirotropis longifolia (SL) and of the ethanol extract of sunflower (Helianthus annuus) seed (SS) and Lonicera japonica Thunb, i.e., honeysuckle (H) on the arginase activity inhibited the enzyme activity.     

Comparison of sample preparation methods for the ICP-AES determination of minor and major elements in clarified apple juices

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the determination of minor and major elements present in apple juices. Prior to ICP-AES measurement, samples were diluted with nitric acid or digested in a microwave assisted digestion system. The differences in the measured element concentrations after application of different types of sample preparation procedures are discussed. The direct measurement compared to closed microwave dissolution was found to be the best sample preparation procedure. Prior to the measurements the ICP-AES method was validated and optimized for the determination of elements in apple juices. For diluted apple juice samples the lowest limits of detection (LOD) were obtained for Ba and Cd (< 20 μg L^{− 1}), moderate ones for Cu, Mn, Ni, Fe, Ag, Ca, Cr, Zn, Mg, and Sr (20–100 μg L^{− 1}), and the highest LODs for K, Pb, Na, and Al (> 110 μg L^{− 1}). The results obtained for the repeatability (< 0.9%), the intermediate precision (< 4.5%), the day-to-day reproducibility (< 5.2%), and the overall uncertainty of measurement (approx. 4–7%) for all elements analyzed demonstrated the good applicability of the proposed method. Differences in major element content in fresh and commercial apple juice are discussed.     

Spectroscopic, morphological, and mechanistic investigation of the solvent-promoted aggregation of porphyrins modified in meso-positions by glucosylated steroids

Solvent-driven aggregation of a series of porphyrin derivatives was studied by UV/Vis and circular dichroism spectroscopy. The porphyrins are characterised by the presence in the meso positions of steroidal moieties further conjugated with glucosyl groups. The presence of these groups makes the investigated macrocycles amphiphilic and soluble in aqueous solvent, namely, dimethyl acetamide/water. Aggregation of the macrocycles is triggered by a change in bulk solvent composition leading to formation of large architectures that express supramolecular chirality, steered by the presence of the stereogenic centres on the periphery of the macrocycles. The aggregation behaviour and chiroptical features of the aggregates are strongly dependent on the number of moieties decorating the periphery of the porphyrin framework. In particular, experimental evidence indicates that the structure of the steroid linker dictates the overall chirality of the supramolecular architectures. Moreover, the porphyrin concentration strongly affects the aggregation mechanism and the CD intensities of the spectra. Notably, AFM investigations reveal strong differences in aggregate morphology that are dependent on the nature of the appended functional groups, and closely in line with the changes in aggregation mechanism. The suprastructures formed at lower concentration show a network of long fibrous structures spanning over tens of micrometres, whereas the aggregates formed at higher concentration have smaller rod-shaped structures that can be recognised as the result of coalescence of smaller globular structures. The fully steroid substituted derivative forms globular structures over the whole concentration range explored. Finally, a rationale for the aggregation phenomena was given by semiempirical calculations at the PM6 level.     

Reversed-Phase Thin-Layer Chromatography of Some Foodstuff Dyes

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of nine frequently used water-soluble food dyes has been studied by TLC on RP-18 silica gel....     

Optical loss measurements in femtosecond laser written waveguides in glass

The optical loss is an important parameter for waveguides used in integrated optics. We measured the optical loss in waveguides written in silicate glass slides with high repetition-rate (MHz) femtosecond laser pulses. The average transmission loss of straight waveguides is about 0.3 dB/mm at a wavelength of 633 nm and 0.05 dB/mm at a wavelength of 1.55 μm. The loss is not polarization dependent and the waveguides allow a minimum bending radius of 36 mm without additional loss. The average numerical aperture of the waveguides is 0.065 at a wavelength of 633 nm and 0.045 at a wavelength of 1.55 μm. In straight waveguides more than 90% of the transmission loss is due to scattering.