1.Formation of halogenated disinfection by-products in cobalt-catalyzed peroxymonosulfate oxidation processes in the presence of halides.
Xie W1, Dong W2, Kong D3, Ji Y2, Lu J4, Yin X2. Chemosphere. 2016 Apr 16;154:613-619. doi: 10.1016/j.chemosphere.2016.04.025. [Epub ahead of print]
Sulfate radicals (SO4-) generated by activation of peroxymonosulfate (PMS) and persulfate (PS) are highly oxidative and applied to degrade various organic pollutants. This research was designed to investigate formation of halogenated by-products in Co2+ activated PMS process in the presence of halides and natural organic matter (NOM). It was revealed that no halogenated by-products were detected in the presence of Cl- while 189 μg/L bromoform and 100.7 μg/L dibromoacetic acid (DBAA) were found after 120 h when 2 mg/L NOM, 0.1 mM Br-, 1.0 mM PMS, and 5 μL Co2+ were present initially. These products are known as disinfection by-products (DBPs) since they are formed in water disinfection processes. Formation of DBPs was even more significant in the absence of Co2+. The data indicate that both PMS and SO4- can transform Br- to reactive bromine species which react with NOM to form halogenated by-products. Less DBP formation in Co2+-PMS systems was due to the further destruction of DBPs by SO4-.
2.Biomechanical evaluation of laser-etched Ti implant surfaces vs. chemically modified SLA Ti implant surfaces: Removal torque and resonance frequency analysis in rabbit tibias.
Lee JT1, Cho SA2. J Mech Behav Biomed Mater. 2016 Apr 7;61:299-307. doi: 10.1016/j.jmbbm.2016.03.034. [Epub ahead of print]
PURPOSE: To compare osseointegration and implant stability of two types of laser-etched (LE) Ti implants with a chemically-modified, sandblasted, large-grit and acid-etched (SLA) Ti implant (SLActive®, Straumann, Basel, Switzerland), by evaluating removal torque and resonance frequency between the implant surface and rabbit tibia bones. We used conventional LE Ti implants (conventional LE implant, CSM implant, Daegu, Korea) and LE Ti implants that had been chemically activated with 0.9% NaCl solution (LE active implant) for comparison with SLActive® implants MATERIALS AND METHODS: Two types of 3.3×8mm laser-etched Ti implants - conventional LE implants and LE active implants were prepared. LE implants and SLActive® implants were installed on the left and right tibias of 10 adult rabbits weighing approximately 3.0kg LE active implants and SLActive® implants were installed on the left and right tibias of 11 adult rabbits. After installation, we measured insertion torque (ITQ) and resonance frequency (ISQ).
3.Designed protein aggregates entrapping carbon nanotubes for bioelectrochemical oxygen reduction.
Garcia KE1, Babanova S2, Scheffler W3, Hans M1, Baker D3, Atanassov P2, Banta S1. Biotechnol Bioeng. 2016 Apr 19. doi: 10.1002/bit.25996. [Epub ahead of print]
The engineering of robust protein/nanomaterial interfaces is critical in the development of bioelectrocatalytic systems. We have used computational protein design to identify two amino acid mutations in the small laccase protein (SLAC) from Streptomyces coelicolor to introduce new inter-protein disulfide bonds. The new dimeric interface introduced by these disulfide bonds in combination with the natural trimeric structure drive the self-assembly of SLAC into functional aggregates. The mutations had a minimal effect on kinetic parameters, and the enzymatic assemblies exhibited an increased resistance to irreversible thermal denaturation. The SLAC assemblies were combined with single-walled carbon nanotubes (SWNTs), and explored for use in oxygen reduction electrodes. The incorporation of SWNTs into the SLAC aggregates enabled operation an elevated temperature and reduced the reaction overpotential. A current density of 1.1 mA/cm2 at 0 V vs.
4.Catalytically active lead(ii)-imidazolium coordination assemblies with diversified lead(ii) coordination geometries.
Naga Babu C1, Suresh P1, Srinivas K1, Sathyanarayana A1, Sampath N2, Prabusankar G1. Dalton Trans. 2016 Apr 19. [Epub ahead of print]
Five Pb(ii)-imidazolium carboxylate coordination assemblies with novel structural motifs were derived from the reaction between the corresponding flexible, semi flexible or rigid imidazolium carboxylic acid ligands and lead nitrate. The imidazolium linker present in these molecules likely plays a triple role such as the counter ion to balance the metal charge, the ligand being an integral part of the final product and the catalyst facilitating carbon-carbon bond formation reaction. These lead-imidazolium coordination assemblies exhibit, variable chemical and thermal stabilities, as well as catalytic activity. These newly prepared catalysts are highly active towards benzoin condensation reactions with good functional group tolerance.