Simulation Assessment of Inlet Parameters and Membrane-Surface-Structure Effects on CO2 Absorption Flux in Membrane Contactors

The management of global carbon dioxide (CO2) emissions is considered one of the main environmental problems facing the modern world. One of the potential techniques for CO2 capture is absorption, using membrane contactor modules. Most of the previous research that dealt with membrane contactor simulations considered the whole membrane surface as the active reaction surface. However, in this paper, a more realistic model of the membrane-contactor module is presented, taking into account the effects of the pore size and surface porosity. CO2 absorption into the monoethanolamine (MEA) solution in hollow fiber membrane-contactor modules was numerically investigated. A computational fluid dynamics simulation was established using essential basic fluid dynamics and mass transfer equations in reactive mode. An algorithmic function was used to present the relations between the CO2 absorption flux and the hollow fiber length, membrane surface pore size, and porosity. The simulation results were compared to previously obtained experimental results without using any fitting parameters, and a good agreement was found with an average error of 8.5%. The validated simulation was then used to predict the effects of the MEA inlet velocity and concentration, the membrane surface pore size, and porosity on the total CO2 absorption flux. A maximum absorption flux of about 1.8 mol/m2·s was achieved at an MEA concentration of 4 M with a pore size of 0.2 microns, a surface porosity of 1%, and an inlet velocity of 0.25 m/s. The extrapolation technique was then used to predict the values of the absorption flux at longer fiber lengths. The concentration profiles around the pores at the gas–liquid contact surface of the membrane were obtained and presented. The proposed model exhibited excellent potential to evaluate the effective reaction surface in hollow fiber membrane contactors. This model could be considered the first step to obtaining accurate predictions of the membrane contactor gas absorption performance based on its surface structure.</jats:p

Anticancer effect of nor-wogonin (5, 7, 8-trihydroxyflavone) on human triple-negative breast cancer cells via downregulation of TAK1, NF-κB, and STAT3

BackgroundNor-wogonin, a polyhydroxy flavone, has been shown to possess antitumor activity. However, the mechanisms responsible for its antitumor activity are poorly studied. Herein, we investigated the mechanisms of nor-wogonin actions in triple-negative breast cancer (TNBC) cells.MethodsEffects of nor-wogonin on cell proliferation and viability of four TNBC cell lines (MDA-MB-231, BT-549, HCC70, and HCC1806) and two non-tumorigenic breast cell lines (MCF-10A and AG11132) were assessed by BrdU incorporation assays and trypan blue dye exclusion tests. Cell cycle and apoptosis analyses were carried out by flow cytometry. Protein expression was analyzed by immunoblotting.ResultsNor-wogonin significantly inhibited the growth and decreased the viability of TNBC cells; however, it exhibited no or minimal effects in non-tumorigenic breast cells. Nor-wogonin (40 μM) was a more potent anti-proliferative and cytotoxic agent than wogonin (100 μM) and wogonoside (100 μM), which are structurally related to nor-wogonin. The antitumor effects of nor-wogonin can be attributed to cell cycle arrest via reduction of the expression of cyclin D1, cyclin B1, and CDK1. Furthermore, nor-wogonin induced mitochondrial apoptosis, (as evidenced by the increase in % of cells that are apoptotic), decreases in the mitochondrial membrane potential (ΔΨm), increases in Bax/Bcl-2 ratio, and caspase-3 cleavage. Moreover, nor-wogonin attenuated the expression of the nuclear factor kappa-B and activation of signal transducer and activator of transcription 3 pathways, which can be correlated with suppression of transforming growth factor-β-activated kinase 1 in TNBC cells.ConclusionThese results showed that nor-wogonin might be a potential multi-target agent for TNBC treatment

Strategy for the management of complex retinal detachments: the European vitreo-retinal society retinal detachment study report 2

OBJECTIVE: To study the outcome of the treatment of complex rhegmatogenous retinal detachments (RRDs). DESIGN: Nonrandomized, multicenter, retrospective study. PARTICIPANTS: One hundred seventy-six surgeons from 48 countries spanning 5 continents reported primary procedures for 7678 RRDs. METHODS: Reported data included clinical manifestations, the method of repair, and the outcome. MAIN OUTCOME MEASURES: Failure of retinal detachment repair (level 1 failure rate), remaining silicone oil at the study's conclusion (level 2 failure rate), and need for additional procedures to repair the detachments (level 3 failure rate). RESULTS: The main categories of complex retinal detachments evaluated in this investigation were: (1) grade B proliferative vitreoretinopathy (PVR; n = 917), (2) grade C-1 PVR (n = 637), (3) choroidal detachment or significant hypotony (n = 578), (4) large or giant retinal tears (n = 1167), and (5) macular holes (n = 153). In grade B PVR, the level 1 failure rate was higher when treated with a scleral buckle alone versus vitrectomy (P = 0.0017). In grade C-1 PVR, there was no statistically significant difference in the level 1 failure rate between those treated with vitrectomy, with or without scleral buckle, and those treated with scleral buckle alone (P = 0.7). Vitrectomy with a supplemental buckle had an increased failure rate compared with those who did not receive a buckle (P = 0.007). There was no statistically significant difference in level 1 failure rate between tamponade with gas versus silicone oil in patients with grade B or C-1 PVR. Cases with choroidal detachment or hypotony treated with vitrectomy had a significantly lower failure rate versus treatment with scleral buckle alone (P = 0.0015). Large or giant retinal tears treated with vitrectomy also had a significantly lower failure rate versus treatment with scleral buckle (P = 7×10(-8)). CONCLUSIONS: In patients with retinal detachment, when choroidal detachment, hypotony, a large tear, or a giant tear is present, vitrectomy is the procedure of choice. In retinal detachments with PVR, tamponade with either gas or silicone oil can be considered. If a vitrectomy is to be performed, these data suggest that a supplemental buckle may not be helpful. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article