An improved algorithm for flux variability analysis.

Flux balance analysis (FBA) is an optimization based approach to find the optimal steady state of a metabolic network, commonly of microorganisms such as yeast strains and Escherichia coli. However, the resulting solution from an FBA is typically not unique, as the optimization problem is, more often than not, degenerate. Flux variability analysis (FVA) is a method to determine the range of possible reaction fluxes that still satisfy, within some optimality factor, the original FBA problem. The resulting range of reaction fluxes can be utilized to determine metabolic reactions of high importance, amongst other analyses. In the literature, this has been done by solving [Formula: see text] linear programs (LPs), with n being the number of reactions in the metabolic network. However, FVA can be solved with less than [Formula: see text] LPs by utilizing the basic feasible solution property of bounded LPs to reduce the number of LPs that are needed to be solved. In this work, a new algorithm is proposed to solve FVA that requires less than [Formula: see text] LPs. The proposed algorithm is benchmarked on a problem set of 112 metabolic network models ranging from single cell organisms (iMM904, ect) to a human metabolic system (Recon3D). Showing a reduction in the number of LPs required to solve the FVA problem and thus the time to solve an FVA problem.

"Inverse" Frustrated Lewis Pairs: An Inverse FLP Approach to the Catalytic Metal Free Hydrogenation of Ketones.

For the first time have boron-containing weak Lewis acids been demonstrated to be active components of Frustrated Lewis Pair (FLP) catalysts in the hydrogenation of ketones to alcohols. Combining the organosuperbase (pyrr)3 P=NtBu with the Lewis acid 9-(4-CF3 -C6 H4 )-BBN generated an "inverse" FLP catalyst capable of hydrogenating a range of aliphatic and aromatic ketones including N-, O- and S-functionalized substrates and bio-mass derived ethyl levulinate. Initial computational and experimental studies indicate the mechanism of catalytic hydrogenation with "inverse" FLPs to be different from conventional FLP catalysts that contain strong Lewis acids such as B(C6 F5 )3 .

Interactions of Verkade's Superbase with Strong Lewis Acids: From Labile Mono- and Binuclear Lewis Acid-Base Complexes to Phosphenium Cations.

A series of mono- and binuclear Lewis acid-base complexes of the formulas N[CH2CH2N(Pri)]3P→LA [LA = BH3 (8), Ga(C6F5)3 (10), GaCl3 (11)], LA←N[CH2CH2N(Pri)]3P [LA = Al(C6F5)3 (6a), AlMe3 (6b), AlEt3 (6c), AlBui3 (6d), BF3 (13)], and LA←N[CH2CH2N(Pri)]3P→LA [Lewis acid (LA) = Al(C6F5)3 (7a), AlMe3 (7b), AlEt3 (7c), AlBui3 (7d), AlCl3 (7e), BH3 (9)] were generated from reactions of Verkade's base, N[CH2CH2N(Pri)]3P (1), with various boron-, aluminum-, and gallium-containing Lewis acids, and characterized by multinuclear NMR spectroscopy. {N[CH2CH2N(Pri)]3P→C7H7}[BF4] (5) was synthesized via the treatment of 1 with [C7H7][BF4]. The reaction of 1 with B(C6F5)3, followed by the addition of [Ph3C]2[B12Cl12], gave rise to the rearranged borate salt [PN4C9H17(Pri)2][B12Cl12] (3), while treating 1 with [Ph3C]2[B12Cl12] exclusively afforded {N[CH2CH2N(Pri)]3PH}2[B12Cl12] (4). Reactions of 1 with 2 equiv of GaCl3 and BF3, respectively, afforded the novel phosphenium gallate and borate salts 12a, 12b, and 15. The solid-state structures of 1, 3-5, 6b, 7a, 7b, 7e, 8, 10, 11, 12b, 13, and 15 were determined by X-ray crystallography.