Differential biocompatibility of carbon nanotubes and nanodiamonds

Carbon nanomaterials are being produced in increasingly larger quantities for many applications due to their novel characteristics such as enhanced thermal, electrical, mechanical, and biological properties. However, there is a lack of data on biological interactions to assess their biocompatibility before they will be accepted as non-toxic in industrial or biomedical arenas. In the present study, we examined both neuronal and lung cell lines for biocompatibility in aqueous suspensions of carbon nanomaterials, such as nanodiamonds (NDs), single- and multi-walled carbon nanotubes (SWNTs, MWNTs), and carbon black (CB), at concentrations ranging from 25–100 μg/ml for 24 h. Our results indicated that these carbon nanomaterials displayed differential biocompatibility in these two different cell lines. The greatest biocompatibility was found after incubation with NDs and both cell types followed the trend: ND > CB > MWNT > SWNT. Macrophages were found to be more sensitive to the nanomaterials with up to five times the generation of reactive oxygen species after incubation with MWNTs or SWNTs. However, there was a lack of ROS generation from either cell line incubated with ND-raw, as well as intact mitochondrial membranes, suggesting that NDs may be useful as a benchmark nanoparticle non-toxic control in replacement of CB, and should be further investigated for use in medical applications.     

Carbon black nanoparticle instillation induces sustained inflammation and genotoxicity in mouse lung and liver

Background

Widespread occupational exposure to carbon black nanoparticles (CBNPs) raises concerns over their safety. CBNPs are genotoxic in vitro but less is known about their genotoxicity in various organs in vivo.

Methods

We investigated inflammatory and acute phase responses, DNA strand breaks (SB) and oxidatively damaged DNA in C57BL/6 mice 1, 3 and 28 days after a single instillation of 0.018, 0.054 or 0.162 mg Printex 90 CBNPs, alongside sham controls. Bronchoalveolar lavage (BAL) fluid was analyzed for cellular composition. SB in BAL cells, whole lung and liver were assessed using the alkaline comet assay. Formamidopyrimidine DNA glycosylase (FPG) sensitive sites were assessed as an indicator of oxidatively damaged DNA. Pulmonary and hepatic acute phase response was evaluated by Saa3 mRNA real-time quantitative PCR.

Results

Inflammation was strongest 1 and 3 days post-exposure, and remained elevated for the two highest doses (i.e., 0.054 and 0.162 mg) 28 days post-exposure (P < 0.001). SB were detected in lung at all doses on post-exposure day 1 (P < 0.001) and remained elevated at the two highest doses until day 28 (P < 0.05). BAL cell DNA SB were elevated relative to controls at least at the highest dose on all post-exposure days (P < 0.05). The level of FPG sensitive sites in lung was increased throughout with significant increases occurring on post-exposure days 1 and 3, in comparison to controls (P < 0.001-0.05). SB in liver were detected on post-exposure days 1 (P < 0.001) and 28 (P < 0.001). Polymorphonuclear (PMN) cell counts in BAL correlated strongly with FPG sensitive sites in lung (r = 0.88, P < 0.001), whereas no such correlation was observed with SB (r = 0.52, P = 0.08). CBNP increased the expression of Saa3 mRNA in lung tissue on day 1 (all doses), 3 (all doses) and 28 (0.054 and 0.162 mg), but not in liver.

Conclusions

Deposition of CBNPs in lung induces inflammatory and genotoxic effects in mouse lung that persist considerably after the initial exposure. Our results demonstrate that CBNPs may cause genotoxicity both in the primary exposed tissue, lung and BAL cells, and in a secondary tissue, the liver.     

Determination methodology for optimising the energy storage size for power system

A methodology for determining the optimal size of energy storage system (ESS) integrated with thermal power system is presented in this study. The optimal size is characterised by the rated stored energy and the maximum power rating of installed ESS for which the power system can achieve maximum revenue. Therefore the ESS cost formulation is conducted by analysing economic cost benefit measures considering life cycle of ESS. Since unit commitment (UC) scheduling is an important and integral part of power system cost optimisation, this study considers the operating schedule of thermal units (TU) while resolving ESS schedule. This proposed method uses tabu search (TS)-based evolutionary technique for solving this optimisation problem. TS is included in this algorithm to avoid re-evaluation of already evaluated ESS size which is powered by max priority heap and hash table data structure. The weekly schedule period is considered instead of daily to achieve more precise results. The proposed method is applied in two different power systems to determine the appropriate size of to be installed ESS. Experimental results reported that establishing the proposed method is an effective one to compute the optimal size of ESS for different sized power systems.     

PMU-based Fault Location Technique for Three-terminal Parallel Transmission Lines with Series Compensation

Abstract

This study introduces a fault location technique for three-terminal series-compensated untransposed parallel transmission lines utilizing the three terminals’ synchronized data. The proposed technique is applicable for short or long lines as distributed parameter line model is employed and the potential couplings are considered. The fault location for both uncompensated line sections is obtained adopting previously introduced fault location technique. The faulty phases are required initially to be recognized for series-compensated transmission line. The adopted fault location technique for series-compensated line section is derived based on the resistive nature of the fault impedance. The obtained fault locations for each line section are compared with each other to distinguish the faulty branch and obtain the fault location. DIgSILENT Power Factory and MATLAB programs are utilized for simulation studies and required calculations. The obtained results prove the efficacy of the introduced technique.     

Discrete wavelet transform and support vector machine‐based parallel transmission line faults classification

This paper presents a scheme for classification of faults on double circuit parallel transmission lines using combination of discrete wavelet transform and support vector machine (SVM). Only one cycle post fault of the phase currents was employed to predict the fault type. Two features for each phase current were extracted using discrete wavelet transform. Thus, a total of 12 features were extracted for the six phase currents. The training data were collected, and SVM was employed to establish the fault classification unit. After that, the fault classification unit was tested for different fault states. The power system simulation was conducted using the MATLAB/Simulink program. The proposed technique took into account the mutual coupling between the parallel transmission lines and the randomness of the faults on transmission line considering time of occurrence, fault location, fault type, fault resistance, and loading conditions. The results show that the proposed technique can classify all the faults on the parallel transmission lines correctly. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Real time evaluation of DWT-based high impedance fault detection in EHV transmission

It is possible to capture the required travelling wave information contained in fault transients using wavelet transform. This paper presents practical real time testing for the high impedance fault (HIF) detection algorithm based on real time accidents data. The proposed scheme is implemented for HIF detection in extra high voltage transmission lines. The classifier is based on an algorithm that uses recursive method to sum the absolute values of the high frequency signal generated over one cycle and shifting one sample. Characteristics of this scheme are analyzed by extensive real time studies that clearly reveal that this technique can accurately detect HIFs in the EHV transmission lines within only half a cycle from the instant of fault occurrence. The reliability of this scheme is not affected by different fault conditions such as fault distance and fault inception angle.     

Preparation of new layered double hydroxide,Zn-Mo LDH

Layered double hydroxide (LDH) is prepared conventionally with bivalent and trivalent cations. We recently reported that the preparation of Zn-Ti LDH consisting of bi and tetravalent cations is possible through the decomposition of urea. In this study, Zn-Mo LDH consisting of bi and hexavalent cations were prepared and reacted with organic monocarboxylic and dicarboxylic acids. Interlayer spacing of the prepared LDH (Zn-Mo-CO₃) contained carbonate anions between the layers was 0.72 nm. The spacing was small compared to usual LDH (Zn-Al-CO₃) of 0.76 nm in the case of carbonate anion as the guest. Also, TG analysis indicated that the electrostatic force between the Zn-Mo layers and carbonate anions was larger than those of Zn-Al LDH. Certainly, the carbonate anions in Zn-Mo LDH decomposed at 260°C while they in usual LDH decomposed at 230–240°C. ESCA showed that Mo⁵⁺ had changed to Mo⁶⁺ through the preparation procedure. These results showed the preparation of layered double hydroxides consisting of bivalent and hexavalent cations. By the intercalation of Zn-Mo LDH with suberic acid at 60°C, a sharp peak was observed at 1.06 nm and the peak of LDH itself (0.72 nm) disappeared. This result has suggested that the intercalation of organic acid into new LDH was performed completely.     

A combined multitasking performance measure involving sequential and parallel task executions

Cognition, Technology & Work - Research on human multitasking suggests several measures to evaluate performance. However, the suggested measures evaluate performance either when tasks are...