The Effect of Various Grinding Aids on the Properties of Cement and Its Compatibility with Acrylate-Based Superplasticizer

The influence of grinding aids (pure triethanolamine and ethylene glycol) on the properties of cements, their compatibility with an acrylate-based superplasticizer and the rheological parameters of mortars were investigated. The presence of surfactants influences the standard properties of cements and the effectiveness of the superplasticizer. The results of the heat of hydration and setting time measurements indicate a delay in the hydration process and an increase in the induction period duration of the surfactant-doped pastes, in relation to the reference sample without grinding aids. Triethanolamine increases early-age compressive strength; the effect was observed for both standard and superplasticizer-containing mortars. The presence of grinding aids decreases the slump flow of mortars and increases rheological parameters such as yield stress (τ0) and viscosity (η).

IR spectroscopy for analysing solvent extraction efficiency of oil extracts

Solvent extraction is a method for purifying oil extracts, which are used as oil-plasticisers for industrial rubber goods, from cancerogenic hydrocarbons. The efficiency of this method is mainly determined by the selectivity and solvent properties of a separating agent. However, when carrying out a comparative analysis of promising extraction methods, it is necessary to use real-time methods for studying the composition of the resulting products. The purification efficiency of oil extracts from polycyclic aromatic components, including carcinogenic hydrocarbons (benzo[a]pyrene, benzo[e]pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, etc.), was evaluated depending upon the nature of selective solvents. The structure-group composition of the purified oil extracts and those at the second-stage of purification was determined by FTIR spectroscopy. It was found that the extraction efficiency of the studied solvents towards polycyclic aromatic hydrocarbons from oil extracts increases in the following order: dimethyl sulfoxide < N-methylpyrrolidone + 10 wt% ethylene glycol <N-methylpyrrolidone +50 wt% triethylene glycol. When using a solvent comprising N-methylpyrrolidone + 50 wt% triethylene glycol, the proportion of polyalkyl-substituted and condensed aromatic structures in the purified oil extract decreases by 16.8%; the oil extract yield increases by over 25 wt% in contrast to extraction with N-methylpyrrolidone + ethylene glycol mixture, which meets the requirements of the European Union for oil extract purification (Directive No. 2005/69/EC). Therefore, we recommend the solvent comprising N-methylpyrrolidone + 50 wt% triethylene glycol for purifying oil extracts from components having a technogenic impact on the environment and human health and IR spectroscopy for efficiency assessment of solvent extraction of oil extracts.

Biocompatibility and Physiological Thiolytic Degradability of Radically-made Thioester-functional Copolymers

Being non-degradable, vinyl polymers have limited biomedical applicability. Unfortunately, backbone esters incorporated through conventional radical ring-opening methods do not undergo appreciable abiotic hydrolysis under physiologically relevant conditions. Here, PEG acrylate and di(ethylene glycol) acrylamide-based copolymers containing backbone thioesters were prepared through the radical ring-opening copolymerization of the thionolactone dibenzo[c,e]oxepin-5(7H)-thione. The thioesters degraded fully in the presence of 10 mM cysteine at pH 7.4, with the mechanism presumed to involve an irreversible S–N switch. Degradations with N-acetylcysteine and glutathione were reversible through the thiol–thioester exchange polycondensation of R–SC(=O)–polymer–SH fragments with full degradation relying on an increased thiolate:thioester ratio. Treatment with 10 mM glutathione at pH 7.2 (mimicking intracellular conditions) triggered an insoluble–soluble switch of a temperature-responsive copolymer at 37 °C and the release of encapsulated Nile Red (as a drug model) from core-degradable diblock copolymer micelles. Copolymers and their cysteinolytic degradation products were found to be non-cytotoxic, making thioester backbone-functional polymers promising for drug delivery applications.

Spectral Fingerprint Investigation in the near Infra-Red to Distinguish Harmful Ethylene Glycol from Isopropanol in a Microchannel

Ethylene glycol (EG) and isopropanol (ISO) are among the major toxic alcohols that pose a risk to human health. However, it is important to distinguish them, since EG is more prone to cause renal failure, and can thus be more dangerous when ingested than ISO. Analysis of alcohols such as isopropanol and ethylene glycol generally can be performed with a complex chromatographic method. Here, we present an optical method based on absorption spectroscopy, performed remotely on EG-ISO mixtures filling a microchannel. Mixtures of ethylene glycol in isopropanol at different volume concentrations were analyzed in a contactless manner in a rectangular-section glass micro-capillary provided with integrated reflectors. Fiber-coupled broadband light in the wavelength range 1.3–1.7 µm crossed the microchannel multiple times before being directed towards an optical spectrum analyzer. The induced zig-zag path increased the fluid–light interaction length and enhanced the effect of optical absorption. A sophisticated theoretical model was developed and the results of our simulations were in very good agreement with the results of the experimental spectral measurements. Moreover, from the acquired data, we retrieved a responsivity parameter, defined as power ratio at two wavelengths, that is linearly related to the EG concentration in the alcoholic mixtures.

Stir bar sorptive-dispersive microextraction by a poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent for the determination of tricyclic antidepressants and their main active metabolites in human urine

A poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent was used for the rapid and sensitive determination of tricyclic antidepressants and their main active metabolites in human urine. This material was characterized by magnetism measurements, zeta potential, scanning electron microscopy, nitrogen adsorption–desorption isotherms, and thermogravimetric analysis. The proposed analytical method is based on stir bar sorptive-dispersive microextraction (SBSDME) followed by liquid chromatography–tandem mass spectrometry. The main parameters involved in the extraction step were optimized by using the response surface methodology as a multivariate optimization method, whereas a univariate approach was employed to study the desorption parameters. Under the optimized conditions, the proposed method was properly validated showing good linearity (at least up to 50 ng mL−1) and enrichment factors (13–22), limits of detection and quantification in the low ng L−1 range (1.4–7.0 ng L−1), and good intra- and inter-day repeatability (relative standard deviations below 15%). Matrix effects were observed for the direct analysis of urine samples, but they were negligible when a 1:1 v/v dilution with deionized water was performed. Finally, the method was successfully applied to human urine samples from three volunteers, one of them consuming a prescribed drug for depression that tested positive for clomipramine and its main active metabolite. Quantitative relative recoveries (80–113%) were obtained by external calibration. The present work expands the applicability of the SBSDME to new analytes and new types of magnetic sorbents. Graphical abstract