Characterisation of carbon nanotubes in the context of toxicity studies

Nanotechnology has the potential to revolutionise our futures, but has also prompted concerns about the possibility that nanomaterials may harm humans or the biosphere. The unique properties of nanoparticles, that give them novel size dependent functionalities, may also have the potential to cause harm. Discrepancies in existing human health and environmental studies have shown the importance of good quality, well-characterized reference nanomaterials for toxicological studies

Remediation technologies for arsenic contaminated drinking waters.

Arsenic is a toxic metalloid element that is now recognised to be an important contaminant of drinking water – particularly, but not exclusively, in poor regions of southern Asia. In effected regions, many millions are at risk of arsenic-induced disease and strategies are required to provide safe water for consumption. The main strategies available are mitigation (the provision of alternative arsenic-free water) and remediation (arsenic removal from extracted water). Consideration of local conditions suggests that for many areas remediation, at an affordable cost, is the only practical option. Remediation technologies are available, but most have been developed for industrial-scale arsenic removal at central water treatment plants. The options for local / personal treatment of water are less well developed. The available methods include arsenic removal by precipitation / co-precipitation and filtration, removal by adsorption onto artificial and natural sorbents, water softening with lime, ion exchange onto activated alumina, membrane processes and bioremediation. This review considers the technical aspects and the appropriateness of these options

An evaluation of the reactivity of synthetic and natural apatites in the presence of aqueous metals

Metal removal from contaminated effluents was examined following reaction with natural apatites of biological and geological origin or a synthetic hydroxylapatite (HAP). Mammalian meat and bone meal (MBM), a by-product from meat industry, was the biological apatite source. The effect of incineration on metal removal capacity of MBM and HAP was also examined. The reactivity of apatites for all tested metals (Pb, Cd, Cu and Zn) followed the general order: synthetic > biological > mineral. For all apatites tested, Pb was removed best and preferentially from multi-metal solutions. MBM and HAP (0.5 g solid) removed Pb completely from both highly concentrated single metal solutions (50 ml, 1000 mg/L Pb) and from multi-metal solutions (50 ml) with 100 mg/L each of Cd, Cu and Zn in addition to Pb. The incineration of MBM (725 °C and 850 °C) reduced significantly its capacity for removal of Zn (by 47%, from 56 mg/g to 9 mg/g) and Cd (by 38%, from 53 mg/g to 13 mg/g) in particular and to a lesser extent for Cu (by 14%, from 61 mg/g to 46 mg/g) while the removal of Pb was not affected (100 mg/g). The same pattern was observed for incinerated HAP. SEM and XRD analysis indicated that HAP reacted with the metals by precipitation of pure metal phosphates-Pb hydroxylapatite, Zn phosphate (hopeite), a Cd phosphate (identified only by ED-SEM) and Cu phosphate (libenthenite). © 2008 Elsevier B.V. All rights reserved

Laser trimming of thick film composite resistors based on nanoforms of carbon

W artykule przedstawiono zagadnienia związane z korekcją elementów biernych metodą piaskową oraz laserową. Wytworzono polimerowe rezystory z trzech rodzajów past rezystywnych: grafenowej, grafitowej i z nanorurek węglowych oraz sprawdzono ich właściwości, m.in. wartości rezystancji, TWR oraz grubości warstw. Przeprowadzono korekcję laserową polegającą na nacinaniu warstwy rezystywnej oraz wykonano szereg badań mających na celu sprawdzenie zmian właściwości elementów biernych po korekcji. Poddano analizie uzyskane wyniki badań pod kątem efektywności korekcji laserowej rezystorów z trzech badanych materiałów.This paper examines issues related to the correction of resistors using the abrasive and laser methods. Three types of resistors, i.e. graphene, graphite and carbon nanotube resistors, were manufactured and their properties such as resistance, TWR and thickness of resistive layers were measured. Laser correction involving cutting of the resistive layer was performed. This part of work included the execution of a series of tests to verify changes in the properties of passive components after trimming. As the final step, the obtained results were analyzed to check the efficiency of laser correction of the resistors based on the three tested materials