Replacing C6F5 groups with Cl and H atoms in frustrated Lewis pairs : H-2 additions and catalytic hydrogenations

2-(Dialkylamino) phenylboranes containing the BXZ group, where X, Z = C6F5, Cl, and H, were prepared in a few synthetic steps and demonstrated the cleavage of H-2 under mild conditions. Depending on the nature of the dialkylamino group, X, and Z, the stability of the produced zwitterionic H-2 adducts varies from isolated solids indefinitely stable in an inert atmosphere to those quickly equilibrating with the initial aminoborane and H-2. Using a combined experimental/computational approach on a series of isostructural aminoboranes (dialkylamino = 2,2,6,6-tetramethylpiperid-1-yl), it was demonstrated that the electro-negativity and the steric effect of the substituents generally follow the trend C6F5 similar to Cl >> H. This observation is useful for designing new FLPs for practical applications. As an example, we demonstrated the hydrogenation of alkynes to cis-alkenes under mild conditions that was catalyzed by a chloro-analogue of the C6F5-substituted aminoborane developed previously. The presence of a BHCl group in the amino-chloroboranes or in their H-2 adducts features facile redistribution of the H and Cl atoms and the formation of polychloro and polyhydrido species.Peer reviewe

Heterogeneous Batch Distillation Processes: Real System Optimisation

In this paper, optimisation of batch distillation processes is considered. It deals with real systems with rigorous simulation of the processes through the resolution full MESH differential algebraic equations. Specific software architecture is developed, based on the BatchColumn® simulator and on both SQP and GA numerical algorithms, and is able to optimise sequential batch columns as long as the column transitions are set. The efficiency of the proposed optimisation tool is illustrated by two case studies. The first one concerns heterogeneous batch solvent recovery in a single distillation column and shows that significant economical gains are obtained along with improved process conditions. Case two concerns the optimisation of two sequential homogeneous batch distillation columns and demonstrates the capacity to optimize several sequential dynamic different processes. For such multiobjective complex problems, GA is preferred to SQP that is able to improve specific GA solutions

Inorganic carbon promotes photosynthesis, growth, and maximum biomass of phytoplankton in eutrophic water bodies

1.The traditional perception in limnology has been that phytoplankton biomass in lakes is limited by phosphorus, nitrogen, and light, but not by dissolved inorganic carbon (DIC) because CO2 can be supplied from the atmosphere. We tested the possibility of carbon limitation of photosynthesis, growth, and biomass accumulation of phytoplankton communities across an alkalinity and DIC gradient (0.15–3.26 mM) in nutrient‐rich freshwater. 2.During 47‐day long experiments, we measured phytoplankton biomass, organic carbon, calcium, DIC, pH, and oxygen in indoor, constantly mixed mesocosms with either no removal or a 70% weekly removal of the biomass. Photosynthesis was measured in the morning and in the afternoon at high biomass. 3.Maximum biomass and organic carbon production increased two‐ to four‐fold with DIC, which supported 7% of organic carbon production at low DIC and 53% at high DIC concentration, while atmospheric CO2 uptake supplied the remainder. Weekly biomass removal increased growth rates through improved light conditions leading to enhanced total phytoplankton biomass production at high DIC. Photosynthesis was significantly higher in the morning compared to afternoon due to daily DIC depletion. 4.We conclude that phytoplankton photosynthesis, growth rate, maximum biomass, and organic carbon production can be markedly carbon limited in eutrophic lake waters. Consequently, lakes of high DIC and pH can support a faster primary production by greater DIC use and chemically enhanced atmospheric CO2 uptake.publishedVersio

Formation of Light Emitting Iron Disilicide/Silicon Heterostructures by Means of Pulsed Ion and Laser Beams

Abstract – Semiconducting iron disilicide (β FeSi2) is a pro mising material for the fabrication of Si based structures emitting light in the 1.5–1.6 μm telecommunication range. In this work β FeSi2/Si heterostructures were formed by high fluence implantation of n Si (100) single crystals with iron ions (Fe+) followed by treatments of the implanted Si la yers with pulsed laser or ion beams. Structural properties of the obtained heterostructures were studied by X ray diffrac tion, transmission electron microscopy and Rutherford backscattering spectrometry. It is shown that pulsed treat ment leads to the formation of nanocrystalline FeSi2 layers with a cellular structure and nearly uniform composition. On the base of β FeSi2/Si layers, light emitting in the near in frared region p+–Si/β FeSi2/n–Si/n+–Si diode structures were obtained by the implantation of low energy boron and phosphorous ions