Search

In this article it is proved that carbon pastes with ionic liquids (ILs) are a promising material for transducers of reference electrodes, which favors their miniaturization. Two ILs were used: 1‐(2‐hydroxyethyl)‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (IL1) and 1‐(2‐methoxyethyl)‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (IL2). They acted both as a binder of carbon paste and potential‐determining component. ILs were also used in polymeric membrane of reference electrodes what ensured continuity of IL phase between carbon paste and the polymeric membrane and resulted in enhancement of electrode potential stability. It was shown that application of IL as a carbon paste binder is superior to conventional plasticizer and allows for significant increase of reference electrode potential stability. Different types of carbon materials were also tested during research: commercialy available graphite powder and graphene oxide obtained from waste biomass – palm kernel shells. It was observed that both the type of carbon paste material and IL influences reference electrode work parameters. Utilization of IL with less lipophilic cation resulted in higher potential stability of the reference electrodes. Application of graphite paste‐based transducers resulted in higher potential stability of reference electrodes in sodium perchlorate and TMA chloride solutions while using palm kernel shell graphene oxide paste – based transducers caused enhancement of reference electrode long‐term potential stability. The results indicate biomass‐derived graphene oxide can be successfully applied as a construction material of reference electrode. [ABSTRACT FROM AUTHOR]

For the ultra high voltage (UHV)‐DC and UHV‐AC transmission lines, their contamination characteristics are different. Thus, researching the contamination polluted degree of UHV‐AC and UHV‐DC lines by geoaccumulation index and enrichment factor method is an ingenious method. This study analyses and compares the chemical composition of contamination on parallel energised UHV‐DC (800 kV) and UHV‐AC (1000 kV) overhead transmission lines. The results indicate that the major cations of insulator contamination are Ca2+, and NH4+, and the major anions of insulator contamination are SO42− and NO3− both on UHV‐DC and UHV‐AC lines. For the UHV‐DC line, the concentrations of the same cations on the insulator bottom surface are higher than that of on the top surface. However, on the UHV‐AC line, the same cation concentrations on the bottom surface close to the one on the top surface. The metallic elements of Ca2+ and Zn2+ are in seriously polluted degree. Also, the polluted degree of contamination on UHV‐DC insulator is more serious than UHV‐AC insulator. This study considers that field charging plays an important role in accumulating contamination. [ABSTRACT FROM AUTHOR]

King cobra ( Ophiophagus hannah) venom l-amino acid oxidase (LAAO), a heat-stable enzyme, is an extremely potent antiproliferative agent against cancer cells when compared with LAAO isolated from other snake venoms. King cobra venom LAAO was shown to exhibit very strong antiproliferative activities against MCF-7 (human breast adenocarcinoma) and A549 (human lung adenocarcinoma) cells, with an IC50 value of 0.04 ± 0.00 and 0.05 ± 0.00 μg/mL, respectively, after 72-hr treatment. In comparison, its cytotoxicity was about 3-4 times lower when tested against human non-tumourigenic breast (184B5) and lung (NL 20) cells, suggesting selective antitumour activity. Furthermore, its potency in MCF-7 and A549 cell lines was greater than the effects of doxorubicin, a clinically established cancer chemotherapeutic agent, which showed an IC50 value of 0.18 ± 0.03 and 0.63 ± 0.21 μg/mL, respectively, against the two cell lines. The selective cytotoxic action of the LAAO was confirmed by phycoerythrin (PE) annexin V/7-amino-actinomycin ( AAD) apoptotic assay, in which a significant increase in apoptotic cells was observed in LAAO-treated tumour cells than in their non-tumourigenic counterparts. The ability of LAAO to induce apoptosis in tumour cells was further demonstrated using caspase-3/7 and DNA fragmentation assays. We also determined that this enzyme may target oxidative stress in its killing of tumour cells, as its cytotoxicity was significantly reduced in the presence of catalase (a H2O2 scavenger). In view of its heat stability and selective and potent cytotoxic action on cancer cells, king cobra venom LAAO can be potentially developed for treating solid tumours. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the use of microwave energy technology to treat granular activated carbon (GAC) which was contaminated with chlorobenzene. GAC is a dielectric material which excellently absorbs microwave energy and then transforms it to thermal energy. The heat generated by the microwave energy is used to decompose the chlorobenzene in the GAC. The study found that after five repetitive uses, the dielectric losses of the GAC declined from 29.8 to 19.4. The removal rate for chlorobenzene also decreased from 100 to 91 percent.

Microwaves were applied to reduce the activation energy of chlorobenzene in aqueous solution and enhance its removal using nanoscale zero-valent iron (Fe0) or zero-valent copper (Cu0) particles as dielectric media. When Fe0 and Cu0 particles absorb microwave energy, the electrical potential difference causes the metal electrons to rotate faster, thus producing more heat. The microwave-irradiated metal particles reduced the chlorobenzene activation energy by 6.1 kj/mol (13.3 kJ/mol versus 19.4 kJ/mol) for Fe0 and 5.4 kJ/mol (15.8 kJ/mol versus 21.4 kj/ mol) for Cu0 and enhanced the chlorobenzene removal 4.1 times (82.8% versus 20.4%) for Fe0 and 3.7 times (72.1% versus 19.5%) for Cu0. The Fe0 has a higher standard reduction potential than Cu0; it is capable of removing more chlorobenzene than Cu0 (82.8% versus 72.1%). Using the microwave-induced nano-scale iron or copper particle is effective in treating toxic organic substances, as demonstrated in this study. [ABSTRACT FROM AUTHOR]

Glutamate clearance by astrocytes is critical for controlling excitatory neurotransmission and ATP is an important mediator for neuron-astrocyte interaction. However, the effect of ATP on glutamate clearance has never been examined. Here we report that treatment of RBA-2 cells, a type-2-like astrocyte cell line, with ATP and the P2X7 receptor selective agonist 3′-O-(4-benzoylbenzoyl) adenosine 5′-triphosphate (BzATP) decreased the Na+-dependent [3H]glutamate uptake within minutes. Mechanistic studies revealed that the decreases were augmented by removal of extracellular Mg2+ or Ca2+, and was restored by P2X7 selective antagonist , periodate-oxidized 2′,3′-dialdehyde ATP (oATP), indicating that the decreases were mediated through P2X7 receptors. Furthermore, stimulation of P2X7 receptors for 2 h inhibited both activity and protein expression of glutamine synthetase (GS), and oATP abolished the inhibition. In addition, removal of extracellular Ca2+ and inhibition of protein kinase C (PKC) restored the ATP-decreased GS expression but failed to restore the P2X7-decreased [3H]glutamate uptake. Therefore, P2X7-mediated intracellular signals play a role in the down-regulation of GS activity/expression. Activation of P2X7 receptors stimulated increases in intracellular Na+ concentration ([Na+]i) suggesting that the P2X7-induced increases in [Na+]i may affect the local Na+ gradient and decrease the Na+-dependent [3H]glutamate uptake. These findings demonstrate that the P2X7-mediated decreases in glutamate uptake and glutamine synthesis were mediated through distinct mechanisms in these cells. [ABSTRACT FROM AUTHOR]