Heterometallic clusters derived from the unsaturated carbyne-bridged dimolybdenum complexes[Mo2(η5-C5H5)2(μ-CPh) (μ-PCy2) (CO)x] (x = 1, 2)

We thank the DGI of Spain for financial support (CTQ2012-33187) and the Consejería de Educacion of Asturias for a grant (to S.M.). We also thank the X-Ray units of Universidad de Oviedo and Universidad de Santiago de Compostela, Spain, for acquisition of diffraction data

Metabolic engineering: Use of system-level approaches and application to fuel production in Escherichia coli

Metabolic engineering was formally defined more than two decades ago (Bailey, 1991) and it is now an established discipline. Metabolic engineering is generally defined as the directed improvement of product formation or cellular properties through the modification of specific biochemical reactions or the introduction of new ones with the use of recombinant DNA technology (Bailey, 1991; Stephanopoulos et al. 1998). Therefore, the analysis and engineering/synthesis of metabolic pathways is of central importance to metabolic engineering. The analytical part uses a number of experimental and modeling techniques for the systematic study of cellular responses (in terms of RNA, protein and metabolite levels, metabolic fluxes, etc.) to genetic and environmental perturbations. This facilitates a rational design of metabolic modifications, which are implemented using recombinant DNA technology. Both, the analysis and the synthesis of metabolic pathways will be covered in this review. Recent efforts on the engineering of fermentative and biosynthetic pathways for biofuel production in Escherichia coli, as well as those enabling the utilization of novel feedstocks, will be highlighted

Efficient Synthesis and Multisite Reactivity of a Phosphinidene-Bridged Mo-Re Complex. A Platform Combining Nucleophilic and Electrophilic Features

We thank the MICINN of Spain and FEDER for financial support (Project PGC2018-097366-B-I00), the Universidad de Oviedo for a grant (to P.V.), the SCBI of the Universidad de Málaga, Spain, for access to computing facilities, and the X-ray unit of the Universidad de Oviedo for acquisition of diffraction data

A widespread alternative squalene epoxidase participates in eukaryote steroid biosynthesis

Steroids are essential triterpenoid molecules that are present in all eukaryotes and modulate the fluidity and flexibility of cell membranes. Steroids also serve as signalling molecules that are crucial for growth, development and differentiation of multicellular organisms1-3. The steroid biosynthetic pathway is highly conserved and is key in eukaryote evolution4-7. The flavoprotein squalene epoxidase (SQE) catalyses the first oxygenation reaction in this pathway and is rate limiting. However, despite its conservation in animals, plants and fungi, several phylogenetically widely distributed eukaryote genomes lack an SQE-encoding gene7,8. Here, we discovered and characterized an alternative SQE (AltSQE) belonging to the fatty acid hydroxylase superfamily. AltSQE was identified through screening of a gene library of the diatom Phaeodactylum tricornutum in a SQE-deficient yeast. In accordance with its divergent protein structure and need for cofactors, we found that AltSQE is insensitive to the conventional SQE inhibitor terbinafine. AltSQE is present in many eukaryotic lineages but is mutually exclusive with SQE and shows a patchy distribution within monophyletic clades. Our discovery provides an alternative element for the conserved steroid biosynthesis pathway, raises questions about eukaryote metabolic evolution and opens routes to develop selective SQE inhibitors to control hazardous organisms

Heavy metals health risk assessment for population via consumption of vegetables grown in old mining area; a case study: Banat County, Romania

<p>Abstract</p> <p>Background</p> <p>The aim of this study is to measure the levels of heavy metals (Fe, Mn, Zn, Cu, Ni, Cd and Pb) found in common vegetables (parsley, carrot, onion, lettuce, cucumber and green beans) grown in contaminated mining areas compared with those grown in reference clear area and to determine their potential detrimental effects via calculation of the daily metal intake (DImetal) and Target Hazard Quotients (THQ) for normal daily consumption of these vegetables, for male and female gender.</p> <p>Results</p> <p>Compared with the reference in contaminated areas, soil and plant contents of all analyzed metals are higher, usually over normally content for Mn, Zn, Cu, Cd and Pb. Particularly, in soil, higher values than intervention threshold values (ITV) were found for Cu and Pb and higher than maximum allowable limits (MAL) for Zn, Cu, Cd and Pb for parsley roots and leaves, carrot roots, cabbage, lettuce and cucumber. DImetal and THQ values for male and female were calculated for each vegetable and metal and for which oral reference doses exist. The combined THQ values calculated are concerning in that they are usually below the safe level of THQ<1 for all vegetables grown in reference area. In contaminated Moldova Noua (M) area the combined THQ exceeded the safe level only for parsley roots, while in more contaminated Ruschita (R) area combined THQ exceeded the safe level for parsley and carrot roots, lettuce and cabbage. Cd and Pb, most toxic metals to humans, have an increasing prevalence in the combined THQ for leafy (cabbage and lettuce) and fruit vegetables (cucumber). In the root vegetables only Pb has an increasing prevalence in combined THQ values. In all areas female THQ is higher than male THQ.</p> <p>Conclusion</p> <p>The results of this study regarding metal contents in soils, vegetables, DImetal and THQ suggest that the consumption of some vegetables (especially parsley, carrot and cabbage and less for lettuce, cucumber and green beans) is not free of risks in these areas. The complex THQ parameter use in health risk assessment of heavy metals provides a better image than using only a simple parameter (contents of metals in soils and vegetables).</p

A Glance at the Recent Additive Manufacturing Research and Development in China

This paper reviews some of the recent additive manufacturing research and development works in China. A considerable amount of AM research activities in China focuses on directed energy deposition processes, powder bed fusion processes and stereolithography, with much of the effect dedicated to system and application development. Although many of the recent results are not readily available from the literatures published in China, from the available information the areas of focus for research and development could be clearly seen. Despite some speculations, the AM research in China is vibrate and aggressive, with some areas at least several years ahead of the other countries.Mechanical Engineerin

Reactions of heterometallic phosphinidene-bridged MoMn and MoRe complexes with sulfur and selenium: from chalcogenophosphinidene- to trithiophosphonate-bridged derivatives

We thank the MICIU and AEI of Spain and FEDER for financial support (projects PGC2018-097366-B-I00 and PID2021-123964NB-I00), the Universidad de Oviedo and Gobierno del Principado de Asturias for a grant (to P.V.)

Studies of electronic communication between dimolybdenum cores joined by various bridges

A series of metal-organic complexes which all contain two bridged dimolybdenum cores were synthesized and studied. Common building blocks involved in this series of syntheses include Mo2(DAniF)3(O2CCH3) (DAniF = N, N'-di-panisylformamidinate) and [Mo2(cis-DAniF)2(NCCH3)4](BF4)2. Bridges that were used to connect two different dimolybdenum cores in the synthesized structures include single metal complexes like ZnCl2 and Ni(acac)2 (acac = acetyl acetone), dimetal complex like Rh2(O2CCH3)4, as well as organic ligands like 1,2-dihydroxyl-4,5-dimethylaminbenzene and 1,3-dihydroxyl-2,5-dimethylaminbenzene. Several heterometallic supramolecules were obtained through self-assembly reactions. In these structures, the two dimolybdenum cores were bridged through different metal complexes; between these metal complexes and the molybdenum cores, isonicotinic acid anion acts as the key linkage. Depending on the geometry of the building blocks and their available binding site, these heterometallic supramolecules bear a variety of shapes, which include rod-like molecules with three metal centers, a squareshaped molecule with its four corners occupied by metal complexes, and also a zigzagshaped infinite metal complex chain. Although these molecules do show reversible redox peaks in electrochemistry studies, they demonstrated very poor electronic communication between the dimolybdenum centers. Possible explanations to this result may be that the dimolybdenum cores are far away from each other in these molecules (Mo2–Mo2 separation in compound 4, being 21 Å, is the longest among all dimolybdenum pairs synthesized to date) and that the calculated frontier orbital overlaps do not favor electron delocalization over the entire molecule. However, another type of molybdenum dimer of dimers where the dimolybdenum centers are united by conjugated organic ligands, namely 1,2-dihydroxyl- 4,5-dimethylaminbenzene and 1,3-dihydroxyl-2,5-dimethylaminbenzene, were also synthesized and found to bear significantly stronger electronic communication between the Mo2 centers. In fact, as electrochemistry reveals, these molecules demonstrated the greatest comproportionation constant values (Kc ~ 1014) than any other analogues synthesized so far. This interesting result is most likely due to the well conjugated linker ligands that would allow electrons on the metal centers to delocalize over the entire molecule. Computational studies of these compounds also show clear evidence of π overlapping in their molecular frontier orbitals

Cycloaddition and C–S bond cleavage processes in reactions of heterometallic phosphinidene-bridged MoRe and MoMn complexes with alkynes and phenyl isothiocyanate

We thank the MICIU and AEI of Spain and FEDER for financial support (Project PID2021-123964NB-I00), the Universidad de Oviedo and Gobierno del Principado de Asturias for a grant (to P.V.)