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Department of Urban and Environmental Engineering (Environmental Science and Engineering)Water resource is essential for humans and many places on the earth, and there needs to solve freshwater shortage caused by water pollution by industrial and farming activities. Nanofiltration (NF) technique has been attracted a lot during past decades, because of its unique characteristics which are utillizing separation mechanisms of both solution diffusion (as in reverse osmosis) and sieving (as in ultrafiltration), resulting to obtain high rejection of divalent salts and organic molecules with low molecular weight (Mw from 200 to 1000) at low operating pressure. Currently, commercial NF polyamide (PA) thin-film composite (TFC) membranes have been generally produced by interfacial polymerization method using piperazine (aliphatic amine monomer) or m-phenylenediamine (MPD, aromatic amine monomer) reacting with trimesoyl chloride (TMC, acyl chloride monomer). The interfacial polymerization methods using piperazine/MPD and TMC are one of the most effective methods to fabricate TFC NF membranes, because the thin/dense polyamide selective layer can make high water flux at low driving-pressure, and the permeable properties can be optimized by several fabrication factors (e.g., monomer concentrations, effective additives, reaction times, and curing time/temperature for post-treatment). The NF technique has been broadly applied to treatment/recycle of the target compounds in acidic conditions: (I) exclusion of heavy metals and sulfate ions in the mining and metal industry, (II) recycling of phosphorus in sewage sludge, (III) treatment of nitric acids in the picture tube production, (IV) regeneration of acidic effluents in dairy cleaning-in-place processes, (V) purification of acidic effluents in the pulp and paper industry, and (VI) separation of plentiful acids such as HBF4, HCl, HNO3, H2SO4, H3BO3 in effluents from rinsing, fermentation, and extraction processes. Additionally, NF technique can be applied to wastewater containing HCl, HBr and HI from semiconductor???s etching process. Acid-stable NF membranes are needed to apply above processes which operate with acidic condition. However, high performance commercial NF semi/full-aromatic PA membranes, which are fabricated by piperazine/MPD with TMC, are limited in the range of pH 2 to 11 in accordance with suppliers. The previous studies were mainly investigated to effect of acidic conditions on PA membranes in the view of permeability. However, both changes of physical and chemical properties by degradation mechanism have not been systematically discussed for semi/full-aromatic membranes after exposure to various acidic conditions up to now. Therefore, a detailed research needs to elucidate effect of acidic degradation on physical and chemical properties of PA membranes using various analytical tools and computational calculation methods. The overall objectives of this work is to systematically examine the effect of the acidic conditions on semi/full-aromatic PA membranes in terms of changes of physical/chemical properties, and to suggest mechanism to explain changed the properties as well as applications for practical fields via various analytical tools: Scanning Electron Microscopy (SEM), Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), contact angle analyzer, electrophoretic light scattering spectrophotometer, filtration tests, and density functional theory (DFT) computational calculations. Experimental results from degradation by acid showed different tendency between semi and full-aromatic PA membrane using acidic aqueous solution (15wt% sulfuric acid). According to analyses of the membrane???s physical and chemical properties (e.g., SEM, ATR-FTIR, XPS, and filtration tests), full-aromatic PA membrane had relatively higher acid-stability than semi-aromatic PA membrane. These degradations by acid cause conversion of an amide group to carboxyl and amine groups measured by ToF-SIMS results. Furthermore, these converted carboxyl and amine groups decreased the contact angle and increased the absolute value of the zeta potential semi-aromatic PA membranes. These difference of acid-stability between semi and full-aromatic PA membrane is resulted from relatively lower energy barrier of semi-aromatic PA membrane in the RDS step. These energy barrier results in the RDS had a close relationship with protonated amides??? twist angle (??D), which shows representative and quantitative value for resonance of amide group. However, full-aromatic PA membrane with relatively higher acid-stability were also severely degraded when it exposed to pH 0 acidic solution containing hydrogen halides. For example, in ATR-FTIR results, amide II band (N-H) in 1541 cm-1 and amide I band (C=O) in 1663 cm-1 after degradation by hydrogen halides tended to decrease due to halogenation reacted with halogens generated by oxidation of hydrogen halides. In addition, water flux after exposure to hydrogen halides tended to severely decrease with increasing exposure time, resulted from broken hydrogen bonding due to halogenation. Meanwhile, acid-catalyzed hydrolysis, which causes conversion amide group into amine and carboxyl group, were applied to post-treatment of semi-aromatic PA membrane in terms of practical applications (e.g., water softening and enrichment of antibiotics). Post-treatment by sulfuric acid in the range of pH 0 to 2 increased membrane???s hydrophilicity, pore size, and absolute value of surface charge. In accordance with change of surface characteristics, mixture selectivity (Na+/Mg2+) for water softening was improved about 2.6 times in acidic conditions. Optimized post-treatment membranes were applied to the enrichment of antibiotics as well, and the membrane had higher water flux and competitive antibiotics rejection compared to other commercial or fabricated membranes. That is, operation time of optimized membrane was improved about 2 to 3 times than virgin semi-aromatic membrane.ope

Post-Treatment of Nanofiltration Polyamide Membrane through Alkali-Catalyzed Hydrolysis to Treat Dyes in Model Wastewater

This research focused on the influence of post-treatment using alkali-catalyzed hydrolysis with a full-aromatic nanofiltration (NF) polyamide membrane and its application to the efficient removal of selected dyes. The post-treated membranes were characterized through Fourier transform infrared spectroscopy, goniometry, and zeta-potential analysis to analyze the treatment-induced changes in the intrinsic properties of the membrane. Furthermore, the changes in permeability induced by the post-treatment were evaluated via the measurement of water flux, NaCl rejection, and molecular weight cutoff (MWCO) under different pH conditions and post-treatment times. Major changes induced by the post-treatment in terms of physicochemical properties were the enhancement of permeability, hydrophilicity, and negative charge due to the hydrolysis of the membrane’s amide bonds. Four different dyes were selected as representative organic pollutants considering the MWCO of the post-treated membranes. Compared with the pristine NF membrane, membranes post-treated at pH 13.5 showed better water flux with similar rejection of the target dyes. On the basis of these results, the proposed post-treatment method for NF membranes can be applied to the removal of organic pollutants of various size

Preparation of Activated Biochar-Supported Magnetite Composite for Adsorption of Polychlorinated Phenols from Aqueous Solutions

For this study, we applied activated biochar (AB) and its composition with magnetite (AB-Fe3O4) as adsorbents for the removal of polychlorophenols in model wastewater. We comprehensively characterized these adsorbents and performed adsorption tests under several experimental parameters. Using FTIR, we confirmed successful synthesis of AB-Fe3O4 composite through cetrimonium bromide surfactant. We conducted adsorption tests using AB and AB-Fe3O4 to treat model wastewater containing polychlorophenols, such as 2,3,4,6-Tetrachlorophenol (TeCP), 2,4,6-Trichlorophenol (TCP), and 2,4-Dichlorophenol (DCP). Results of the isotherm and the kinetic experiments were well adapted to Freundlich’s isotherm model and the pseudo-second-order kinetic model, respectively. Main adsorption mechanisms in this study were attributed to non-covalent, π-electron acceptor–donor interactions and hydrophobic interactions judging from the number of chloride elements in each chlorophenol and its hydrophobic characteristics. We also considered the electrostatic repulsion effect between TeCP and AB, because adsorption performance of TeCP at basic condition was slightly worse than at weak acidic condition. Lastly, AB-Fe3O4 showed high adsorption selectivity of TeCP compared to other persistent organic pollutants (i.e., bisphenol A and sulfamethoxazole) due to hydrophobic interactions. We concluded that AB-Fe3O4 may be used as novel adsorbent for wastewater treatment including toxic and hydrophobic organic pollutants (e.g., TeCP)

Endovascular Embolization of Intracranial Aneurysms Using Bare Platinum Axium™ Detachable Coils: Immediate and Short-Term Follow-up Results from a Multicenter Registry

PurposeAxium™ coils were developed to improve the durability of coil-embolized cerebral aneurysms by increasing packing density. The purpose of this prospective multicenter registry was to evaluate the safety and durability of Axium™ coils.Materials and MethodsOne hundred twenty-six patients with 135 aneurysms of ≤ 15 mm in size underwent coil embolization using bare platinum coils, with Axium™ coils constituting over 50% of the total coil length. Immediate and short-term follow-up results were prospectively registered and retrospectively evaluated.ResultsOf the 135 aneurysms (83 unruptured and 52 ruptured), immediate post-embolization angiography revealed complete occlusion in 80 aneurysms (59.3%), neck remnants in 47 (34.8%), and incomplete occlusion in 8 (5.9%). The mean packing density was 42.8% (range, 9.5 - 90%) with Axium™ coil length constituting a mean of 87.9% of total coil length. The rate of procedure-related complications was 16.3%. Procedure-related permanent morbidity and mortality rates were 3.2% and 0.8%, respectively. Follow-up catheter or MR angiography, which was available in 101 aneurysms at 6 - 15 months (mean, 7.7 months), revealed stable or improved occlusion in 95 aneurysms and worsening in 6 aneurysms (5.9%). Lower packing density (< 30%) remained the only predictor for anatomical worsening on multivariable logistic regression analysis (P < 0.05).ConclusionIn this registry, Axium™ coils showed a relatively low rate of anatomical worsening on short-term follow-up imaging with an acceptable periprocedural safety profile compared to reports of other platinum coils. These results may warrant further study of long-term durability with Axium™ coils in larger populations

Sonodegradation of amitriptyline and ibuprofen in the presence of Ti3C2Tx MXene

This study, which investigated the sonodegradation of selected pharmaceutical active compounds (PhACs) (amitriptyline (AMT) and ibuprofen (IBP)) with MXene, was carried out in an aqueous solution. To investigate the practicality of the degradation process, the experiments were conducted in various water quality conditions, including pH, temperature, natural organic matter, and ionic strength. Based on the experimental results, the produced hydrogen peroxide, which could be a representative of the produced OH radicals, was a vital factor that affected the degradation performance of both PhACs. To confirm the importance of OH radicals, the effect of a OH radical promoter (H2O2) and scavenger (t-BuOH) was also studied. In addition, the synergism between ultrasonication (US) and MXene was evaluated with the rate constants of US only, MXene only, and a US/MXene combined system. Mineralization of the PhACs was also investigated, and removal of AMT was higher than that of IBP, which could be attributed to the physicochemical properties of the compounds and enhanced adsorption by the well-dispersed MXene. Overall, utilization of MXene by means of ultrasonication could enhance the removal performance of PhACs in water

Cyr61 Expression is associated with prognosis in patients with colorectal cancer

BACKGROUND: Cysteine-rich 61 (Cyr61), a member of the CCN protein family, possesses diverse functionality in cellular processes such as adhesion, migration, proliferation, and survival. Cyr61 can also function as an oncogene or a tumour suppressor, depending on the origin of the cancer. Only a few studies have reported Cyr61 expression in colorectal cancer. In this study, we assessed the Cyr61 expression in 251 colorectal cancers with clinical follow up. METHODS: We examined Cyr61 expression in 6 colorectal cancer cell lines (HT29, Colo205, Lovo, HCT116, SW480, SW620) and 20 sets of paired normal and colorectal cancer tissues by western blot. To validate the association of Cyr61 expression with clinicopathological parameters, we assessed Cyr61 expression using tissue microarray analysis of primary colorectal cancer by immunohistochemical analysis. RESULTS: We verified that all of the cancer cell lines expressed Cyr61; 2 cell lines (HT29 and Colo205) demonstrated Cyr61 expression to a slight extent, while 4 cell lines (Lovo, HCT116, SW480, SW620) demonstrated greater Cyr61 expression than HT29 and Colo205 cell lines. Among the 20 cases of paired normal and tumour tissues, greater Cyr61 expression was observed in 16 (80%) tumour tissues than in normal tissues. Furthermore, 157 out of 251 cases (62.5%) of colorectal cancer examined in this study displayed strong Cyr61 expression. Cyr61 expression was found to be associated with pN (p = 0.018). Moreover, Cyr61 expression was associated with statistically significant cancer-specific mortality (p = 0.029). The duration of survival was significantly lesser in patients with Cyr61 high expression than in patients with Cyr61 low expression (p = 0.001). These results suggest that Cyr61 expression plays several important roles in carcinogenesis and may also be a good prognostic marker for colorectal cancer. CONCLUSIONS: Our data confirmed that Cyr61 was expressed in colorectal cancers and the expression was correlated with worse prognosis of colorectal cancers

Thermally modulated multilayered graphene oxide for hydrogen storage

We have obtained high pressure H(2) isotherms with respect to the interlayer distance of multilayered graphene oxide (GO) modulated by thermal annealing. The maximum storage capacity is 4.8 (0.5) wt% at 77 K (298 K) and at 9.0 MPa pressure. We found the optimum GO interlayer distance for maximum H2 uptake at 6.5 angstrom, similar to the predicted distances from first-principles calculations for graphite materials. Our results reveal that multilayered GO can be a practical material of choice to allow the use of graphene as a hydrogen storage material, provided that only small amounts of O and OH functional groups exist as spacers on GO sheets.close171