Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. I

Structures of six cyclic polysulfides, previously unknown as organic environmental pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography connected to mass spectrometry. High resolution (HRMS) measurements of the isotopic composition of four compounds could be done to confirm their molecular formulae. Total low resolution (LRMS) spectra were used to elucidate structures of all six compounds by thermochemical approach, application of fragmentation rules and by ICLU simulation of the spectra. The compounds were deduced to be (in the order of GC- retention) 1,2,4-trithiacycloheptane, tetrathiacyclopentane, 1,2,4,5-tetrathia-cyclohexane, 1,2,3,4- tetrathiacycloheptane, 1,2,3,4-tetrathiacyclohexane and 1,2,4,6-tetrathiacyclooctane.     

Stereoselective Synthesis and Retentive Trapping of α‐Chiral Secondary Alkyllithiums Leading to Stereodefined α,β‐Dimethyl Carboxylic Esters

The treatment of α‐chiral secondary alkyl iodides with tBuLi at ?100 °C leads to the corresponding secondary alkyllithiums with high retention of configuration. Subsequent quenching with various electrophiles such as Bu₂S₂, DMF, MeOB(OR)₂, or Et₂CO provides the desired products with retention of configuration. Furthermore, a transmetalation with CuBr?P(OEt)₃ also allows retentive trapping with acid chlorides and ethylene oxide. The quenching of the resulting alkyllithiums with ClCO₂Et furnishes stereoselectively syn‐ and anti‐ethyl‐2,3‐dimethyl ester carboxylates (d.r.>94 %). Related esters bearing three adjacent stereo‐controlled centers (stereotriads) have also been prepared. This method has been applied to the synthesis of the ant pheromone (±)‐lasiol in 26 % overall yield (four steps) with d.r.=97:3 starting from commercially available cis‐2,3‐epoxybutane.     

Synthesis of Novel Lipophilic Polyamines via Ugi Reaction and Evaluation of Their Anticancer Activity

Natural polyamines (PAs) are involved in the processes of proliferation and differentiation of cancer cells. Lipophilic synthetic polyamines (LPAs) induce the cell death of various cancer cell lines. In the current paper, we have demonstrated a new method for synthesis of LPAs via the multicomponent Ugi reaction and subsequent reduction of amide groups by PhSiH₃. The anticancer activity of the obtained compounds was evaluated in the A-549, MCF7, and HCT116 cancer cell lines. For the first time, it was shown that the anticancer activity of LPAs with piperazine fragments is comparable with that of aliphatic LPAs. The presence of a diglyceride fragment in the structure of LPAs appears to be a key factor for the manifestation of high anticancer activity. The findings of the study strongly support further research in the field of LPAs and their derivatives.     

Effects of Hydrogen Peroxide on In Vitro Cultures of Tea (Camellia sinensis L.) Grown in the Dark and in the Light: Morphology,Content of Malondialdehyde,and Accumulation of Various Polyphenols

Tea plants (Camellia sinensis L.) are phenol-accumulating crops that are widely used for public health. The healing effect of tea leaf products is due to the biosynthesis of such phenolic compounds (PCs) as flavans, which have P-vitamin capillary-strengthening activity. Due to their limited habitat and the value of their specialized metabolites of a phenolic nature, a promising approach is to establish in vitro cultures from them that retain the ability to form PCs, which is characteristic of ex vivo tea plants. The aim of this study was to investigate the effect of exogenic H₂O₂ (0.01 mM; 0.1 mM; 1 mM) on the growth, morphology, degree of stress response, and accumulation of various phenolic compounds in tea plant callus cultures of different ages (24 or 36 days) grown under different cultivation conditions (darkness or light). According to the results obtained, the H₂O₂ effect on tea callus cultures of different ages did not cause changes in their morphophysiological characteristics, both after 2 h of exposure (rapid response of callus culture, RRCC) and after 48 h (delayed response of callus culture, DRCC). The determination of the malondialdehyde (MDA) content, which serves as an indicator of changes in the level of lipid peroxidation (LPO) and the presence of stress responses in plant cells, indicated either its maintenance at the control level, a decrease, or an increase. All these effects depended on the growth conditions of the tea callus cultures (darkness or light), their age, the duration of exposure (rapid or delayed response), and the H₂O₂ concentration. Similar trends were noted for the total content of PCs as well as the amount of flavans, proanthocyanidins (soluble and insoluble forms), and lignin. The plant cell responses reflected changes in its adaptation programs, when specialized metabolites act as a target for the action of H₂O₂, thereby contributing to an increase in their resistance.     

Nanomaterials in Cementitious Composites: An Update

This review is an update about the addition of nanomaterials in cementitious composites in order to improve their performance. The most common used nanomaterials for cementitious materials are carbon nanotubes, nanocellulose, nanographene, graphene oxide, nanosilica and nanoTiO₂. All these nanomaterials can improve the physical, mechanical, thermal and electrical properties of cementitious composites, for example increase their compressive and tensile strength, accelerate hydration, decrease porosity and enhance fire resistance. Cement based materials have a very complex nanostructure consisting of hydration products, crystals, unhydrated cement particles and nanoporosity where traditional reinforcement, which is at the macro and micro scale, is not effective. Nanomaterials can reinforce the nanoscale, which wasn’t possible heretofore, enhancing the performance of the cementitious matrix.     

Crystal structure and chemical bonding in tin(II) acetate

Tin(II) acetate was prepared and its crystal structure was solved from X-ray powder diffraction data. Tin(II) acetate adopts a polymeric structure consisting of infinite Sn(CH₃COO)₂ chains running along the c-axis which are packed into groups of four. The acetate groups bridge the Sn atoms along the chains. The Sn atoms are asymmetrically surrounded by four oxygen atoms with two short Sn–O distances (2.170(6), 2.207(6) Å) and two longer ones (2.293(7), 2.372(8) Å). The coordination environment of the Sn atoms is completed up to a strongly distorted trigonal bipyramid SnO₄E by the sterically active lone electron pair E. The coordination environment of the Sn atoms is virtually identical for Sn(CH₃COO)₂ in the gaseous and solid phase: the two short Sn–O bonds and the lone electron pair are located in the equatorial plane of the trigonal bipyramid and the two longer Sn–O bonds are directed towards the apical vertexes. Localization of the lone electron pair on Sn(II) was confirmed by electron localization function (ELF) analysis. The polymeric nature of the tin(II) acetate crystal structure was confirmed by a MALDI-TOF experiment.     

A multi-methodological approach to the development of a regional solid waste management system

The management of solid waste at regional level has received considerable attention over the last years. Increased consumption levels are causing an exacerbation of the problem, whereas the sensitivity of the public over environmental issues makes its solution harder. Although the main difficulties in resolving the different occurrences of the problem belong to the realm of policy making, so far the employment of operational research and systems methods seems to adopt a purely technocratic stance, concentrating on the content and understating the solution process. In the different formulations of the problem as static optimization relating to the economics of the location of the treatment facilities and the methods and routes of waste transportation, the dynamics of the issue and the intervention activities are neglected, whereas cognitive and social perspectives of the solution process are objectified and over-rationalized. This paper aims at demonstrating how the solid waste management (SWM) problem and its solution process can be addressed in a more holistic way by adopting a multi-methodological point of view. Towards this end, we present the combined application of soft systems methodology, system dynamics and multi-objective optimization in an action research project for the development of an SWM system for a specific region in Greece.