Confocal micro-Raman investigation of multilayer systems

The modern technologies use many multilayer composites comprising, the connection of different classes substrates: ceramics, metals, polymers, etc. In this work we focused our attention on an application of confocal micro-Raman spectroscopy to study the multilayer composites. Different multilayer model systems were used to check the role of the confocal mode. The problem of the transparency of layer, and their thickness were discussed. The procedure of determination of interfaces from so-called depth profiles and their first derivatives was also presented.     

Small libraries of fused quinazolinone-sugars. Access to quinazolinedione nucleosides

Unprotected carbohydrates can readily be converted into base-modified nucleosides and deoxynucleosides through a short sequence involving the condensation of anthranilic acid derivatives with a suitably protected sugar-derived 2-alkylthio-1,3-oxazoline.     

Synthesen und Molekülstrukturen von [Cu20Ga10Cl4Se23(PEt2Ph)12] und [Cu14In6Se7(iPrSe)18]

Syntheses and Structures of [Cu₂₀Ga₁₀Cl₄Se₂₃(PEt₂Ph)₁₂] and [Cu₁₄In₆Se₇(iPrSe)₁₈] CuCl and GaCl₃ react with Se(SiMe₃)₂ in thf solution to yield in the presence of PEt₂Ph [Cu₂₀Ga₁₀Cl₄Se₂₃(PEt₂Ph)₁₂] ( 1 ). Reaction of CuCl, InCl₃ and TMEDA with iPrSeSiMe₃ in DME results in the crystallisation of [Cu₁₄In₆Se₇(iPrSe)₁₈] ( 2 ). The structures of 1 and 2 were determined by X‐ray single crystal structure analysis and display two new types of molecular clusters formed by the elements of group 11, 13, and 16. However, both cluster structures show no analogy to the structures of the related bulk phases.     

Influence of Surface-Active Compounds on Starch Dispersion in Water. Part I. Starch Pasting

The influence of native lipids and additives of surface-active compounds on starch paste rheology was investigated. The aim of the study was to gain better understanding of mechanisms involved in starch gelatinization and how these structure changes of granules later affect rheological properties of pastes and gels. Starches from three main sources—potato, maize, and wheat—were tested; sodium dodecylsulfate, oleate, and benzalkonium chloride were employed as additives. Starch pasting was examined by a rheometer to get a viscosity profile, also pastes were analyzed by differential scanning calorimetry, for particle size using a light scattering technique. Results revealed that there was a competition between native lipids and added surfactants for amylose complexation. Complexes formed during gelatinization were strongly affecting granule swelling and dissolution of starch polymers, and viscosity of pastes was mainly dependent on the particle size of a disperse phase in the paste. Addition of strong ionic surfactants to cereal starches resulted in smaller granular remnants and, therefore, decreased viscosity, while the weak anionic surfactant promoted an increase in the particle size and paste viscosity for both cereal and tuber starches. The mechanism of the effect of surfactants on the particle size in pastes is discussed.     

Properties and determination of pesticides in fruits and vegetables

The intensive development of agriculture means that more and more toxic organic and inorganic compounds are entering the environment. Because of their widespread use, stability, selective toxicity and bioaccumulation, pesticides are among the most toxic substances contaminating the environment. They are particularly dangerous in fruit and vegetables, by which people are exposed to them. It is therefore crucial to monitor pesticide residues in fruit and vegetables using all available analytical methods.We set out the problems in the determination of organonitrogen and organophosphorus pesticides in samples of fruit and vegetables, including the complexity and the diversity of matrices in biological materials, and the very low level of pesticides present, as a result of which target analytes have to be isolated and then enriched prior to final determination.We discuss the various stages in the determination of pesticide residues in fruit and vegetables. We present results from the literature in the context of Maximum Residue Levels (MRLs) of target pesticides in fruit and vegetable samples. We discuss the merits of the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) technique and two-dimensional gas chromatography.     

Determination of β-blockers and β-agonists using gas chromatography and gas chromatography-mass spectrometry--a comparative study of the derivatization step

There is a growing demand for the rapid screening of multiple β-blockers and β-agonists in a single analytical run in clinical toxicology, antidoping control, forensic and environmental science. Although GC-MS is very often used to determine pharmaceuticals from these groups of drugs, the literature data on the derivatization and MS analysis of mixtures of these compounds is limited. This paper compares and evaluates derivatization procedures for the determination of six β-blockers (acebutolol, atenolol, metoprolol, nadolol, propranolol, pindolol) and two β-agonists (salbutamol, terbutaline) using GC techniques. Nineteen different derivatizing reagents (nine of them used for the first time with almost all the drugs) were employed in order to obtain a single derivative for each target compound with the greatest effectiveness of this reaction. Trimethylsilylation, tert-butyldimethylsilylation, acylation (e.g. trifluoroacetylation), combined trimethylsilylation and acylation, and the formation of cyclized silyl derivatives were carried out and the mass spectra (EI, 70 eV) recorded. The influence of the reaction time and temperature on these procedures was investigated. Additionally, the effects of the type of solvent and the amount of added trimethylchlorosilane (TMCS) on the silylation of the target compounds using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) were tested. Among of the five mentioned above derivatization procedures applied - trimethylsilylation was found to be the most effective for derivatizing the analytes. The best results were obtained with a 1:1 (v/v) mixture of 99% BSTFA+1% TMCS and ethyl acetate at 60 °C for 30 min. The MS data for different types of β-blocker and β-agonist derivatives is presented. The information in this paper is valuable for scientists working on the determination of β-blockers and β-agonists in biological and environmental matrices.     

Antiviral Potential of Plants against Noroviruses

Human noroviruses, which belong to the enterovirus family, are one of the most common etiological agents of food-borne diseases. In recent years, intensive research has been carried out regarding the antiviral activity of plant metabolites that could be used for the preservation of fresh food, because they are safer for consumption when compared to synthetic chemicals. Plant preparations with proven antimicrobial activity differ in their chemical compositions, which significantly affects their biological activity. Our review aimed to present the results of research related to the characteristics, applicability, and mechanisms of the action of various plant-based preparations and metabolites against norovirus. New strategies to combat intestinal viruses are necessary, not only to ensure food safety and reduce infections in humans but also to lower the direct health costs associated with them.     

Improvement of the resistance to oxidation of the ecological greases by the additives

This article presents the results of research aimed at improving the oxidation stability of the ecological greases addressed toward application in machines working in the food industry. In order to improve the functional properties of grease, additives that modify the thermal stability have been added. Then, the influence of the additive on the grease resistance to the oxidation was examined. The results of tests of lubricants containing different types of additives are presented. The thermal examinations of the greases were carried out with the use of scanning differential calorimetry techniques. The lubricated properties of greases were investigated with the use of a four-ball tribotester. Based on the results, the relationships between the kind of additive, the resistance to oxidation and the lubricated properties of the grease were analysed, and the relationships between thermal and antiwear properties of grease were identified. Based on the results of this research, a new formulation of grease was proposed, which meets both the ecological needs and the working conditions in the food industry.     

An entry to 7-amino- and to 2-ethoxycarbonyl-5-dethia-5-oxa-cephams from 1,3-alkylidene-l-erythritol

The alkoxyallene derived from 1,3-benzylidene-l-erythritol when treated with chlorosulfonyl isocyanate provided diastereomeric β-lactams with moderate stereoselectivity. After the intramolecular alkylation of the nitrogen atom, these afforded compounds having oxacepham skeletons. The exo-isopropylidene group enabled the introduction of a variety of substituents to the C-7 carbon atom of the cepham, whereas removal of the benzylidene protection followed by the oxidation of 3-OH to the ketone allowed carboxylation of the C-2 carbon atom.