Temporary feeding shocks increase the productivity in a continuous biohydrogen-producing reactor

Continuous hydrogen production stability and robustness by dark fermentation were comprehensively studied at laboratory scale. Continuous bioreactors were operated at two different hydraulic retention times (HRT) of 6 and 10 hours. The reactors were subjected to feeding shocks given by decreases in the HRT, and therefore the organic loading increase, during 6 and 24 hours. Results indicated that the H2 productivity was significantly improved by the temporary organic shock loads, increasing the hydrogen production rate up to 40%, compared to the rate obtained at the steady-state condition. Besides, it was observed that after the shock load, the stability of the reactor (measured as the hydrogen production rate) was recovered attaining the values observed before the feeding shocks. The bioreactor operated at shorter HRT (6 h) showed better H2 productivity (17.3 ± 1.1 L H2/L-d) in comparison to the other one operated at 10 h HRT (12.4 ± 1.6 L H2/L-d)

Evaluation of various cheese whey treatment scenarios in single-chamber microbial electrolysis cells for improved biohydrogen production

In this study single-chamber microbial electrolysis cells (MECs) were applied to treat cheese whey (CW), an industrial by-product, and recover H2 gas. Firstly, this substrate was fed directly to the MEC to get the initial feedback about its H2 generation potential. The results indicated that the direct application of CW requires an adequate pH control to realize bioelectrohydrogenesis and avoid operational failure due to the loss of bioanode activity. In the second part of the study, the effluents of anaerobic (methanogenic) digester and hydrogenogenic (dark fermentative H2-producing) reactor utilizing the CW were tested in the MEC process (representing the concept of a two-stage technology). It turned out that the residue of the methanogenic reactor – with its relatively lower carbohydrate- and higher volatile fatty acid contents – was more suitable to produce hydrogen bioelectrochemically. The MEC operated with the dark fermentation effluent, containing a high portion of carbohydrates and low amount of organic acids, produced significant amount of undesired methane simultaneously with H2. Overall, the best MEC behavior was attained using the effluent of the methanogenic reactor and therefore, considering a two-stage system, methanogenesis is an advisable pretreatment step for the acidic CW to enhance the H2 formation in complementary microbial electrohydrogenesis

Feasibility of quaternary ammonium and 1,4-diazabicyclo[2.2.2]octane-functionalized anion-exchange membranes for biohydrogen production in microbial electrolysis cells

In this work, two commercialized anion-exchange membranes (AEMs), AMI-7001 and AF49R27, were applied in microbial electrolysis cells (MECs) and compared with a novel AEM (PSEBS CM DBC, functionalized with 1,4-diazabicyclo[2.2.2]octane) to produce biohydrogen. The evaluation regarding the effect of using different AEMs was carried out using simple (acetate) and complex (mixture of acetate, butyrate and propionate to mimic dark fermentation effluent) substrates. The MECs equipped with various AEMs were assessed based on their electrochemical efficiencies, H2 generation capacities and the composition of anodic biofilm communities. pH imbalances, ionic losses and cathodic overpotentials were taken into consideration together with changes to substantial AEM properties (particularly ion-exchange capacity, ionic conductivity, area- and specific resistances) before and after AEMs were applied in the process to describe their potential impact on the behavior of MECs. It was concluded that the MECs which employed the PSEBS CM DBC membrane provided the highest H2 yield and lowest internal losses compared to the two other separators. Therefore, it has the potential to improve MECs

Investigation of Anticancer Properties of Monoterpene-Aminopyrimidine Hybrids on A2780 Ovarian Cancer Cells

The present study aimed to characterize the antiproliferative and antimetastatic properties of two recently synthesized monoterpene-aminopyrimidine hybrids (1 and 2) on A2780 ovary cancer cells. Both agents exerted a more pronounced cell growth inhibitory action than the reference agent cisplatin, as determined by the MTT assay. Tumor selectivity was assessed using non-cancerous fibroblast cells. Hybrids 1 and 2 induced changes in cell morphology and membrane integrity in A2780 cells, as evidenced by Hoechst 33258–propidium iodide fluorescent staining. Cell cycle analysis by flow cytometry revealed substantial changes in the distribution of A2780 ovarian cancer cells, with an increased rate in the subG1 and G2/M phases, at the expense of the G1 cell population. Moreover, the tested molecules accelerated tubulin polymerization in a cell-free in vitro system. The antimetastatic properties of both tested compounds were investigated by wound healing and Boyden chamber assays after 24 and 48 h of incubation. Treatment with 1 and 2 resulted in time- and concentration-dependent inhibition of migration and invasion of A2780 cancer cells. These results support that the tested agents may be worth of further investigation as promising anticancer drug candidates

Antiproliferative and Antimetastatic Properties of 16-Azidomethyl Substituted 3-O-Benzyl Estrone Analogs

Four diastereomers of 16-azidomethyl substituted 3-O-benzyl estradiol (1–4) and their two estrone analogs (16AABE and 16BABE) were tested for their antiproliferative properties against human gynecological cancer cell lines. The estrones were selected for additional experiments based on their outstanding cell growth-inhibiting activities. Both compounds increased hypodiploid populations of breast cancer cells, and 16AABE elicited cell cycle disturbance as evidenced by flow cytometry. The two analogs substantially increased the rate of tubulin polymerization in vitro. 16AABE and 16BABE inhibited breast cancer cells’ migration and invasive ability, as evidenced by wound healing and Boyden chamber assays. Since both estrone analogs exerted remarkable estrogenic activities, as documented by a luciferase reporter gene assay, they can be considered as promising drug candidates for hormone-independent malignancies

Investigation of Anticancer Properties of Monoterpene-Aminopyrimidine Hybrids on A2780 Ovarian Cancer Cells

The present study aimed to characterize the antiproliferative and antimetastatic properties of two recently synthesized monoterpene-aminopyrimidine hybrids (1 and 2) on A2780 ovary cancer cells. Both agents exerted a more pronounced cell growth inhibitory action than the reference agent cisplatin, as determined by the MTT assay. Tumor selectivity was assessed using non-cancerous fibroblast cells. Hybrids 1 and 2 induced changes in cell morphology and membrane integrity in A2780 cells, as evidenced by Hoechst 33258-propidium iodide fluorescent staining. Cell cycle analysis by flow cytometry revealed substantial changes in the distribution of A2780 ovarian cancer cells, with an increased rate in the subG1 and G2/M phases, at the expense of the G1 cell population. Moreover, the tested molecules accelerated tubulin polymerization in a cell-free in vitro system. The antimetastatic properties of both tested compounds were investigated by wound healing and Boyden chamber assays after 24 and 48 h of incubation. Treatment with 1 and 2 resulted in time- and concentration-dependent inhibition of migration and invasion of A2780 cancer cells. These results support that the tested agents may be worth of further investigation as promising anticancer drug candidates

Supported ionic liquid membrane based on [bmim][PF6] can be a promising separator to replace Nafion in microbial fuel cells and improve energy recovery: A comparative process evaluation

In this study, mixed culture bioelectrochemical systems were operated with various membrane separators: one prepared with 1-Butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) ionic liquid and another one called Nafion, used as reference for comparative evaluation. In the course of experiments, the primary objective was to reveal the influence of membranes-type on microbial fuel cell (MFC) behavior by applying a range of characterization methods. These included cell polarization measurements, monitoring of dehydrogenase enzyme activity and cyclic voltammetry for the analysis of anode biofilm properties and related electron transfer mechanism. Additionally, MFC performances for both membranes were assessed based on Coulombic efficiency as well as substrate (acetate) concentration dependency of energy yields. As a result, it was demonstrated that the ionic liquid-containing membrane could be suitable to compete with Nafion and appears as a candidate to be further investigated for microbial electrochemical applications