Cymodienol and cymodiene: new cytotoxic diarylheptanoids from the sea grass Cymodocea nodosa

The two new diarylheptanoids, cymodienol (1), and cymodiene (2), obtained from specimens of the sea grass Cymodocea nodosa, collected from the coastal areas of central Greece, are the first members of this class isolated from marine organisms. The chemical structures of the two metabolites were assigned on the basis of their NMR and MS spectroscopic data, including information obtained by 1D- and 2D-NMR experiments. Metabolite 2 possesses an unprecedented skeleton that might be biosynthetically related to metabolite 1. Cymodienol (1) was found to exhibit significant cytotoxic activity against two lung cancer cell lines.     

Synthesis, structural characterization and electrochemical study of 1,1′-ferrocenylene labeled amino acids

Unsymmetrical 1,1′-disubstituted ferrocenes bearing an amino acid moiety and a conjugated electron density controlling substituent were synthesized conveniently starting from 1,1′-ferrocenedicarbaldehyde. The novel ferrocene amino acid derivatives were completely characterized from their MS, ¹H NMR and ¹³C NMR spectra. Their electrochemical behavior was studied by cyclic voltammetry. Their formal redox potentials E_f were slightly influenced by the nature of the amino acid and mainly by the kind of the ethenyl substituent. Furthermore all the (Z)-isomers exhibited a slight anodic shift compared with the corresponding (E)-isomers.     

Development of an epi-fluorescence assay for monitoring yeast viability and pretreatment hydrolysate toxicity in the presence of lignocellulosic solids

Applied Biochemistry and Biotechnology -     

Changes of gross gamma-ray intensity in a submarine spring system due to a distant earthquake event on 30th of March 2019 at Itea,Greece

Journal of Radioanalytical and Nuclear Chemistry - A medium resolution underwater in-situ gamma-ray spectrometer (GeoMAREA) was deployed in the submarine spring (Kiveri) for continuous monitoring...     

Folded overlapping variance estimators for simulation

We propose and analyze a new class of estimators for the variance parameter of a steady-state simulation output process. The new estimators are computed by averaging individual estimators from “folded” standardized time series based on overlapping batches composed of consecutive observations. The folding transformation on each batch can be applied more than once to produce an entire set of estimators. We establish the limiting distributions of the proposed estimators as the sample size tends to infinity while the ratio of the sample size to the batch size remains constant. We give analytical and Monte Carlo results showing that, compared to their counterparts computed from nonoverlapping batches, the new estimators have roughly the same bias but smaller variance. In addition, these estimators can be computed with order-of-sample-size work.     

A Convenient and Efficient Process to 5-(2-Di-n-Propylaminoethyl)-6-hydroxyindole

An intermolecular trapping of the Pummerer intermediate, generated from 9 with TFAA, by 4 at position 5 under mild Lewis acid conditions gave 5. Sequential treatment of 5 with Ra-Ni, LiAlH₄ and again Ra-Ni, afforded 8 in high overall yield.     

On the Effect of Secondary Nucleation on Deracemization through Temperature Cycles

Herein, the pivotal role of secondary nucleation in a crystallization-enhanced deracemization process is reported. During this process, complete and rapid deracemization of chiral conglomerate crystals of an isoindolinone is attained through fast microwave-assisted temperature cycling. A parametric study of the main factors that affect the occurrence of secondary nucleation in this process, namely agitation rate, suspension density, and solute supersaturation, confirms that an enhanced stereoselective secondary nucleation rate maximizes the deracemization rate. Analysis of the system during a single temperature cycle showed that, although stereoselective particle production during the crystallization stage leads to enantiomeric enrichment, undesired kinetic dissolution of smaller particles of the preferred enantiomer occurs during the dissolution step. Therefore, secondary nucleation is crucial for the enhancement of deracemization through temperature cycles and as such should be considered in further design and optimization of this process, as well as in other temperature cycling processes commonly applied in particle engineering.