Enhanced electrochemical removal of sulfadiazine using stainless steel electrode coated with activated algal biochar.

With the increasingly discharging and inappropriately disposing of antibiotics from human disease treatment and breeding industry, extensive development of antibiotic resistance in bacteria raised serious public health concern. In this work, algal biochar was coated onto the stainless steel mesh, and was employed as cathodic electrode for the degradation of sulfadiazine (SDZ) in an electro-Fenton (EF) system. It was found that algal biochar pyrolyzed at 600 °C with 1:1 KOH achieved best catalytic performance to generate H2O2 via oxygen reduction. Moreover, removal efficiency of SDZ reached 96.11% in 4 h with an initial concentration of 25 µg/mL, under the optimized condition as: initial pH at 3, 50 mM of Na2SO4 as electrolyte and an applied current of 20 mA/cm2. In addition, it was found that the SDZ removal kept at about 96.99% even after four repeated degradation process. Moreover, four possible SDZ degradative pathways during the EF process were proposed according to determined intermediates, model optimization and density functional theory calculation. Finally, acute and chronic biotoxicity of the degradative products against fish and green algae was evaluated, to further elaborate the environmental impact of SDZ after electrochemical degradation.

Housing of electrosynthetic biofilms using a roll-up carbon veil electrode increases CO2 conversion and faradaic efficiency in microbial electrosynthesis cells.

Electrode-driven microbial electron transfer enables the conversion of CO2 into multi-carbon compounds. The electrosynthetic biofilms grow slowly on the surface and are highly susceptible to operational influences, such as hydrodynamic shear stress. In this study, a cylindrical roll-up carbon felt electrode was developed as a novel strategy to protect biofilms from shear stress within the reactor. The fabricated electrode allowed hydrogen bubble formation inside the structure, which enabled microbes to uptake hydrogen and convert CO2 to multi-carbon organic compounds. The roll-up electrode exhibited faster start-up and biofilm formation than the conventional linear shape carbon felt. The acetate yield and cathodic faradaic efficiency increased by 80% and 34%, respectively, and the bioelectrochemical stability was improved significantly. The roll-up structure increased biofilm development per unit electrode surface by three to five-fold. The roll-up configuration improved biofilm formation on the electrode, which enhanced the performance of microbial electrosynthesis-based CO2 valorization.

[Effects of modification of transferrin on cytotoxicity and intracellular delivery of paclitaxel loaded PLGA nanoparticles].

OBJECTIVE: To evaluate the effects of modification of transferrin on cytotoxicity and intracellular delivery of paclitaxel loaded Poly (lactide-co-glycolide) (PLGA) nanoparticle (NPs). METHODS: PLGA NPs were formulated with microemulsion method, Polyvinyl alcohol (PVA) was used as surfactant (PVA NPs). Transferrin (Tf) was used to modify the NPs (Tf NPs). The cytotoxicity of paclitaxel solution and paclitaxel loaded PVA NPs and Tf NPs were measured in bladder cancer cell line J-82. The intracellular delivery of two kinds of NPs was measured. RESULTS: The half maximal inhibitory concentration (IC50) of paclitaxel loaded PVA NPs and Tf NPs was (44 ± 7) and (49 ± 11) ng/ml respectively and significantly lower than that of paclitaxel solution, which was (81 ± 18) ng/ml (both P < 0.05). The uptake of PVA NPs and Tf NPs by J-82 cells after 2 hours was (89 ± 19) µg/mg cellular protein and (76 ± 16) µg/mg cellular protein. The uptake of two kinds of NPs had no significantly difference. The intracellular level of NPs decreased significantly upon the withdrawal of NPs in medium. However, it became stable 2 hours later and 11.3% PVA NPs and 18.0% Tf NPs remained. The intracellular level of PVA NPs and Tf NPs had no significantly difference at any time point. NPs were distributed in cytoplasm after endocytosis. CONCLUSIONS: PLGA NPs can significantly improve the anti-neoplastic effect of paclitaxel on bladder cancer. However, modification of Tf does not change the intracellular dynamics.

Effects of D-arginine on Porphyromonas gingivalis biofilm.

Porphyromonas gingivalis (P. gingivalis) is one of the major pathogenic bacteria of periodontitis or peri-implantitis. P. gingivalis tends to attach to the implant's neck with the formation of biofilm, leading to peri-implantitis. d-arginine has been shown to have a potential antimicrobial role. In this study, P. gingivalis was cultured in Brain Heart Infusion broth together with d-arginine. After 3 days (inhibition) or 6 days (dissociation), these were characterized using crystal violet (CV) staining for the biofilm, extracellular polysaccharide (EPS) production from the biofilm, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay for biofilm activation. Furthermore, the P. gingivalis biofilm was observed by scanning electron microscopy (SEM). d-arginine effectively reduced biomass accumulation and promoted dissociation at concentrations of ≥50 mM and 100 mM, respectively. Through CV staining, d-arginine concentrations of EPS production from the biofilm for inhibition and dissociation effects was ≥50 mM and 100 mM, respectively. In addition, d-arginine affected biofilm activation for the corresponding concentrations: ≥60 mM for inhibition and ≥90 mM for dispersal. Under SEM observation, d-arginine changed the P. gingivalis biofilm structure in relatively high concentrations for inhibition or dissociation, respectively. The authors concluded that d-arginine could inhibit the formation of P. gingivalis biofilm and promote the dissociation of P. gingivalis biofilm.

Experimental study on denitrification using coated electrode of immobilized denitrifying bacteria.

OBJECTIVE: To develop a coated electrode of immobilized denitrificants and to evaluate the performance of a bioelectrochemical reactor to enhance and control denitrification. METHODS: Denitrifying bacteria were developed by batch incubation and immobilized with polyvinyl alcohol (PVA) on the surface of activated carbon fiber (ACF) to make a coated electrode. Then the coated electrode (cathode) and graphite electrode (anode) were transferred to the reactor to reduce nitrate. RESULTS: After acclimated to the mixtrophic and autotrophic denitrification stages, the denitrifying bacteria could use hydrogen as an electron donor to reduce nitrate. When the initial nitrate concentration was 30.2 mg NO3- -N / L, the denitrification efficiency was 57.3% at an applied electric current of 15 mA and a hydraulic retention time (HRT) of 12 hours. Correspondingly, the current density was 0.083 mA/cm2. The nitrate removal rate of the reactor was 34.4 g NO3- -N/m3 x d, and the surface area loading was 1.34 g NO3- -N / m2 x d. CONCLUSION: The coated electrode may keep high quantity of biomass, thus achieving a high denitrification rate. Denitrification efficiencies are related to HRT, current density, oxidation reduction potential (ORP), dissolved oxygen (DO), pH value, and temperature.

[Shape-memory alloy net-like stent for the management of ureteral stricture: a long-term follow-up report].

OBJECTIVE: To investigate the long-term outcome of treatment of ureteral stricture with shape-memory alloy net-like stent. METHODS: Nickel-titanium shape-memory alloy net-like stent was used to treat 9 patients with ureteral stricture, 4 males and 5 females, aged 41 (29-63), with the length of ureteral stricture of 1.0-4.0 cm, the etiology being radical operation for rectal carcinoma in 2 cases, chronic inflammation in 3 case, and operation for benign diseases in 4 cases. A total of 10 stents were inserted under spinal anesthesia. The mean follow-up time was 27.2 months (5-96 months). RESULTS: Ureteral obstruction was relieved in 7 cases (77.8%) with the relief or disappearance of hydronephrosis. The ureteral stents were blocked and re-obstruction appeared in 2 cases within 5-6 months due to hyperplasia of fibrous tissue. One of the cases underwent removal of stent and the other case underwent insertion of double-J with improvement of renal function. No radiological evidence of migration of stent and encrustation was found. CONCLUSION: More tolerable and with less side-effect and lower re-stricture rate, shape-memory alloy stent is better then Double-J in treatment of ureteral obstruction.