Structures and Unexpected Dynamic Properties of Phosphine Oxides Adsorbed on Silica Surfaces

Solid‐state NMR spectroscopy of selected phosphine oxides adsorbed on silica surfaces establishes the surface mobilities, even of phosphine oxides with high melting points. Crystal structures of the adducts Ph₃PO ? HOSiPh₃ and Cy₃PO ? H₂O indicate that the interactions with silica involve hydrogen bonding of the P?O group to adsorbed water and surface silanol groups.     

Commercial Origanum compactum Benth. and Cinnamomum zeylanicum Blume essential oils against natural mycoflora in Valencia rice

Chemical composition of commercial Origanum compactum and Cinnamomum zeylanicum essential oils and the antifungal activity against pathogenic fungi isolated from Mediterranean rice grains have been investigated. Sixty-one compounds accounting for more than 99.5% of the total essential oil were identified by using gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). Carvacrol (43.26%), thymol (21.64%) and their biogenetic precursors p-cymene (13.95%) and γ-terpinene (11.28%) were the main compounds in oregano essential oil, while the phenylpropanoids, eugenol (62.75%), eugenol acetate (16.36%) and (E)-cinnamyl acetate (6.65%) were found in cinnamon essential oil. Both essential oils at 300 μg/mL showed antifungal activity against all tested strains. O. compactum essential oil showed the best antifungal activity towards Fusarium species and Bipolaris oryzae with a total inhibition of the mycelial growth. In inoculated rice grains at lower doses (100 and 200 μg/mL) significantly reduced the fungal infection, so O. compactum essential oil could be used as ecofriendly preservative for field and stored Valencia rice.     

Development of a silica monolith modified with Fe3O4 nano‐particles in centrifugal spin column format for the extraction of phosphorylated compounds

In this study, citrate‐stabilised iron oxide nano‐particles (～16 nm) have been immobilised on commercial silica monolithic centrifugal spin columns (MonoSpin) for the extraction of phosphorylated compounds. Two alternative strategies were adopted involving either direct electrostatic attachment to an aminated MonoSpin (single‐layer method) in the first instance, or the use of a layer‐by‐layer method with poly(diallyldimethylammonium) chloride. Field‐emission scanning electron spectroscopy and energy‐dispersive X‐ray spectroscopy was used for confirming notably higher coverage of nano‐particles using the layer‐by‐layer method (2.49 ± 0.53 wt%) compared with the single‐layer method (0.43 ± 0.30 wt%). The modified monolith was used for the selective separation/extraction of adenosine monophosphate, adenosine diphosphate and adenosine triphosphate with elution using a phosphate buffer. A reversed‐phase liquid chromatographic assay was used for confirming that adenosine, as a non‐phosphorylated control was not retained on the modified MonoSpin devices, whereas recovery of 80% for adenosine monophosphate, 86% for adenosine diphosphate and 82% for adenosine triphosphate was achieved.     

Oxidative Decarboxylation of Short‐Chain Fatty Acids to 1‐Alkenes

The enzymatic oxidative decarboxylation of linear short‐chain fatty acids (C4:0–C9:0) employing the P450 monooxygenase OleT, O₂ as the oxidant, and NAD(P)H as the electron donor gave the corresponding terminal C₃ to C₈ alkenes with product titers of up to 0.93 g L^?1 and TTNs of >2000. Key to this process was the construction of an efficient electron‐transfer chain employing putidaredoxin CamAB in combination with NAD(P)H recycling at the expense of glucose, formate, or phosphite. This system allows for the biocatalytic production of industrially important 1‐alkenes, such as propene and 1‐octene, from renewable resources for the first time.     

Hydrogen Peroxide and Di(hydroperoxy)propane Adducts of Phosphine Oxides as Stoichiometric and Soluble Oxidizing Agents

Aqueous hydrogen peroxide is widely used as an oxidizing agent in industry and academia. Herein, the hydrogen peroxide adducts of phosphine oxides, [tBu₃PO ? H₂O₂]₂ and [Ph₃PO ? H₂O₂]₂ ? H₂O₂, are described. Additionally, the corresponding di(hydroperoxy)propane adducts R₃PO ? (HOO)₂CMe₂ (R=Cy, Ph) were synthesized and characterized. All adducts could be obtained as large single crystals suitable for structural characterization by X‐ray crystallography and solid‐state NMR spectroscopy. The di(hydroperoxy)propane adducts are soluble in organic solvents which enables oxidation reactions in one phase. As the adducts are solid and molecular, they can easily be applied stoichiometrically. No loss of oxidizing power occurs upon long‐term storage of the single crystals at room temperature or the powders at ?20 °C.     

Sensitive method for the determination of lipophilic marine biotoxins in extracts of mussels and processed shellfish by high-performance liquid chromatography–tandem mass spectrometry based on enrichment by solid-phase extraction

A solid-phase extraction (SPE) method for the enrichment and clean-up of lipophilic marine biotoxins from extracts of different species of bivalve molluscs and processed shellfish products was developed. Okadaic acid (OA), pectenotoxin2 (PTX2), azaspiracid1 (AZA1) and yessotoxin (YTX) were determined by LC–MS/MS in hydrolyzed and non-hydrolyzed extracts. Applying a concentration factor of 10 the limit of quantification for the four toxins was determined to be 1 μg/kg. An organized in-house ring trial proved transferability of the method protocol and satisfactory results for all four toxins with a relative standard deviation (RSD) of 5–12%. The precision of the whole method including LC–MS detection was determined by processing seven independent extractions analyzed in independent sequences. RSD ranged between 12% and 24%. This SPE method was tested within a concentration range corresponding to the range of the current European Union regulatory limits (up to 160 μg/kg for the OA group), but it would also be applicable to a lower μg/kg range which is important in view of a possible decrease of regulatory limits as proposed by a working group of the European Food Safety Authority. The potential of SPE as a cleaning tool to cope with matrix effects in LC–MS/MS was studied and compared to liquid–liquid portioning.     

Heuristic algorithms for a complex parallel machine scheduling problem

In this work we present a new scheduling model for parallel machines, which extends the multiprocessor scheduling problem with release times for minimizing the total tardiness, and also extends the problem of vehicle routing with time windows. This new model is motivated by a resource allocation problem, which appears in the service sector. We present two class of heuristic algorithms for the solution of the problem, the first class is a class of greedy algorithms, the second class is based on the solutions of linear assignment problems. Furthermore we give a rescheduling algorithm, which improves a given feasible solution of the problem. This research has been supported by the Hungarian National Foundation for Scientific Research, Grant T046405.