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Metabolic engineering has expanded in importance and employment in recent years and is now extensively applied particularly in the production of biomass from microbes. Metabolic network models have been employed extravagantly in computational processes developed to enhance metabolic production and suggest changes in organisms. The crucial issue has been the unrealistic flux distribution presented in prior work on rational modelling framework adopting Optknock and OptGene. In order to address the problem, a hybrid of Bees Algorithm and Regulatory On/Off Minimization (BAROOM) is used. By employing Escherichia coli as the model organism, the most excellent set of genes in E. coli that can be removed and advance the production of succinate can be decided. Evidences shows that BAROOM outperforms alternative strategies used to escalate in succinate production in model organisms like E. coli by selecting the best set of genes to be removed.

The effects of surface treatment with TiCl4 on the structural and electrochemical properties of a porous titanium oxide (pTiO2) layer deposited on a fluorine-doped tin oxide (FTO)/glass substrate covered with a dense TiO2 layer (pTiO2/dTiO2/FTO/glass) were systematically investigated in order to obtain an optimum pTiO2 layer for use in CH3NH3PbI3 perovskite solar cells. As confirmed by thermal desorption spectroscopy (TDS) analyses, the amount of surface hydroxyl groups in pTiO2 varied when the pTiO2/dTiO2/FTO/glass sample was treated with solutions with different concentrations of TiCl4 (i.e., 20, 50, 80, and 100 mM). Photoelectrochemical (PEC) analyses of the pTiO2/dTiO2/FTO/glass samples after TiCl4 treatment showed significant increments of photocurrent densities compared to the pTiO2/dTiO2/FTO/glass sample without TiCl4 treatment regardless of the concentration of TiCl4 used in the solution. Electrochemical impedance spectroscopy (EIS) analyses of the TiCl4-treated pTiO2/dTiO2/FTO/glass samples also indicated a lower recombination probability with an increase in TiCl4 concentration. The results suggest that TiCl4 treatment resulted in passivation of defect sites on the surface of the TiO2 nanoparticles as well as improvement of the interconnectivity between the TiO2 nanoparticles in pTiO2. In contrast, the power conversion efficiencies (PCEs) and short circuit current densities of CH3NH3PbI3 perovskite solar cells based on these pTiO2/dTiO2/FTO/glass samples exhibited volcano-like patterns depending on the TiCl4 concentration used for the pTiO2 treatment: the highest PCE was obtained by using pTiO2/dTiO2/FTO/glass treated with 50 mM of TiCl4 solution. Structural analysis of the CH3NH3PbI3 perovskite part performed by X-ray diffraction (XRD) indicated that the formation of CH3NH3PbI3 perovskite was inhibited by the presence of surface hydroxyl groups in the pTiO2 film without TiCl4 treatment. TiCl4 treatment using TiCl4 solutions with concentrations up to 50 mM enhanced the formation of the CH3NH3PbI3 perovskite layer, whereas TiCl4 treatment using TiCl4 solutions with concentrations higher than 50 mM was detrimental due to the formation of nanoparticulate TiO2 aggregates that induce poor porosity and act as recombination sites. [ABSTRACT FROM AUTHOR]

The effects of surface treatment with TiCl 4 on the structural and electrochemical properties of a porous titanium oxide (pTiO 2 ) layer deposited on a fluorine-doped tin oxide (FTO)/glass substrate covered with a dense TiO 2 layer (pTiO 2 /dTiO 2 /FTO/glass) were systematically investigated in order to obtain an optimum pTiO 2 layer for use in CH 3 NH 3 PbI 3 perovskite solar cells. As confirmed by thermal desorption spectroscopy (TDS) analyses, the amount of surface hydroxyl groups in pTiO 2 varied when the pTiO 2 /dTiO 2 /FTO/glass sample was treated with solutions with different concentrations of TiCl 4 (i.e., 20, 50, 80, and 100 mM). Photoelectrochemical (PEC) analyses of the pTiO 2 /dTiO 2 /FTO/glass samples after TiCl 4 treatment showed significant increments of photocurrent densities compared to the pTiO 2 /dTiO 2 /FTO/glass sample without TiCl 4 treatment regardless of the concentration of TiCl 4 used in the solution. Electrochemical impedance spectroscopy (EIS) analyses of the TiCl 4 -treated pTiO 2 /dTiO 2 /FTO/glass samples also indicated a lower recombination probability with an increase in TiCl 4 concentration. The results suggest that TiCl 4 treatment resulted in passivation of defect sites on the surface of the TiO 2 nanoparticles as well as improvement of the interconnectivity between the TiO 2 nanoparticles in pTiO 2 . In contrast, the power conversion efficiencies (PCEs) and short circuit current densities of CH 3 NH 3 PbI 3 perovskite solar cells based on these pTiO 2 /dTiO 2 /FTO/glass samples exhibited volcano-like patterns depending on the TiCl 4 concentration used for the pTiO 2 treatment: the highest PCE was obtained by using pTiO 2 /dTiO 2 /FTO/glass treated with 50 mM of TiCl 4 solution. Structural analysis of the CH 3 NH 3 PbI 3 perovskite part performed by X-ray diffraction (XRD) indicated that the formation of CH 3 NH 3 PbI 3 perovskite was inhibited by the presence of surface hydroxyl groups in the pTiO 2 film without TiCl 4 treatment. TiCl 4 treatment using TiCl 4 solutions with concentrations up to 50 mM enhanced the formation of the CH 3 NH 3 PbI 3 perovskite layer, whereas TiCl 4 treatment using TiCl 4 solutions with concentrations higher than 50 mM was detrimental due to the formation of nanoparticulate TiO 2 aggregates that induce poor porosity and act as recombination sites.