Scale-up and large-scale production of Tetraselmis sp CTP4 (Chlorophyta) for CO2 mitigation: from an agar plate to 100-m(3) industrial photobioreactors

Industrial production of novel microalgal isolates is key to improving the current portfolio of available strains that are able to grow in large-scale production systems for different biotechnological applications, including carbon mitigation. In this context, Tetraselmis sp. CTP4 was successfully scaled up from an agar plate to 35-and 100-m(3) industrial scale tubular photobioreactors (PBR). Growth was performed semi-continuously for 60 days in the autumn-winter season (17th October -14th December). Optimisation of tubular PBR operations showed that improved productivities were obtained at a culture velocity of 0.65-1.35 m s(-1) and a pH set-point for CO2 injection of 8.0. Highest volumetric (0.08 +/- 0.01 g L-1 d(-1)) and areal (20.3 +/- 3.2 g m(-2) d(-1)) biomass productivities were attained in the 100-m(3) PBR compared to those of the 35-m(3) PBR (0.05 +/- 0.02 g L-1 d(-1) and 13.5 +/- 4.3 g m(-2) d(-1), respectively). Lipid contents were similar in both PBRs (9-10% of ash free dry weight). CO2 sequestration was followed in the 100-m(3) PBR, revealing a mean CO2 mitigation efficiency of 65% and a biomass to carbon ratio of 1.80. Tetraselmis sp. CTP4 is thus a robust candidate for industrial-scale production with promising biomass productivities and photosynthetic efficiencies up to 3.5% of total solar irradiance.Portuguese national budget; Foundation for Science and Technology (FCT) [CCMAR/Multi/04326/2013]; INTERREG V-A Espana-Portugal project [0055 ALGARED + 5 E]; COST Action - European Network for Bio-products [1408]; FCT [SFRH/BD/105541/2014]; Nord Universityinfo:eu-repo/semantics/publishedVersio

A density functional study of open-shell cyclopentadienyl-molybdenum(II) complexes. A comparison of stabilizing factors: Spin-pairing, Mo-X pi bonding, and release of steric pressure

The dissociation of PH3 from the is-electron system CpMoX(PH3)(3) to afford the corresponding 16-electron CpMoX(PH3)(2) fragment has been investigated theoretically by density functional theory for X = H, CH3, F, Cl, Br, I, OH, and PH2. The product is found to prefer a tripler spin state for all X ligands except PH2, the singlet-tripler gap varying between 1.7 kcal/mol for OH to 8.7 kcal/mol for F. The Mo-PH3 bond dissociation energy to the 16-electron ground state varies dramatically across the series, from 4.5 kcal/mol for OH to 23.5 kcal/mol for H, and correlates with experimental observations on trisubstituted phosphine derivatives. Geometry-optimized spin doublet CpMo(PH3)(3), on the other hand, has a Mo-PH3 bond dissociation energy of 24.3 kcal/mol. The modulation of the Mo-PH bond dissociation energy by the introduction of X is analyzed in terms of three effects that stabilize the 16-electron product relative to the 18-electron starting complex: (i) adoption of the higher (triplet) spin state by release of pairing energy; (ii) Mo-X pi interactions; (iii) release of steric pressure. A computational model for the approximate separation and evaluation of these three stabilizing effects is presented. According to the results of these calculations, the relative importance of the three effects depends on various factors related to the nature of X. For double-sided pi-donor X ligands, the larger triplet-singlet gap is provided by the more electronegative atoms (F > Cl > Br > I), whereas single-sided pi donors favor the singlet state. The pi-stabilization ability goes in the order PH2 > OH > F > other halogens > H. Finally, the major steric interaction appears to be associated with the presence of inactive lone pairs and by their orientation/proximity to the PH3 ligands (Cl, Br > I, OH > F, PH2, H, CH3). The 16-electron methyl system establishes a marked alpha-agostic interaction in the singlet state, which nevertheless remains unfavored relative to an undistorted tripler configuration

Detailed structural investigation of the grafting of [Ta(=CHtBu)(CH(2)tBu)(3)] and [Cp*TaMe4] on silica partially dehydroxylated at 700 degrees C and the activity of the grafted complexes toward alkane metathesis

The reaction of [Ta(=CHtBu)(CH(2)tBu)(3)] or [Cp*Ta(CH3)(4)] with a silica partially dehydroxylated at 700 degreesC gives the corresponding monosiloxy surface complexes [(=SIO)Ta(=CHtBu)(CH(2)tBu)(2)] and [(=SiO)Ta(CH3)(3)Cp*] by eliminating a a-bonded ligand as the corresponding alkane (H-CH(2)tBu or H-CH3). EXAFS data show that an adjacent siloxane bridge of the surface plays the role of an extra surface ligand, which most likely stabilizes these complexes as in [(equivalent toSiO)Ta(=CHtBu)(CH(2)tBU)(2)(equivalent toSiOSiequivalent to)] (1a') and [(equivalent toSiO)Ta(CH3)(3)Cp*(equivalent toSiOSiequivalent to)] (2a'). In the case of [(=SiO)Ta(equivalent toCHtBu)(CH(2)tBu)(2)(equivalent toSiOSiequivalent to)], the structure is further stabilized by an additional interaction: a C-H agostic bond as evidenced by the small J coupling constant for the carbenic C-H (J(C-H) = 80 Hz), which was measured by J-resolved 2D solid-state NMR spectroscopy. The product selectivity in propane metathesis in the presence of [(=SIO)Ta(equivalent toCHtBu)(CH(2)tBu)(2)(equivalent toSiOSiequivalent to)] (1a') as a catalyst precursor and the inactivity of the surface complex [(equivalent toSIO)Ta(CH3)(3)Cp*(equivalent toSiOSiequivalent to)] (2a') show that the active site is required to be highly electrophilic and probably involves a metallacyclobutane intermediate

Environmental impact of thin-film GaInP/GaAs and multicrystalline silicon solar modules produced with solar electricity

Sustainable housing transformationsOTB Research Institut