Tribological behaviour of copper oxide nanoparticle suspension

This work presents and discusses the tribological behaviour of nanoparticle suspensions in a polyalphaolefin (PAO6). CuO nanoparticles were separately dispersed at 0.5, 1.0 and 2.0% wt. in PAO6 using an ultrasonic probe for 2 minutes. AW properties were obtained using a TE53SLIM tribometer with a block-on-ring configuration and EP properties were obtained using a Four-Ball machine according to ASTM D2783. Wear surfaces were analyzed by SEM and EDS after tests. The study led to the following conclusions: nanoparticle suspensions exhibited reductions in friction and wear compared to the base oil; CuO suspensions showed the highest friction coefficient and lowest wear per nanoparticle content of 2%; all concentrations of nanoparticles improved the EP properties of PAO6; CuO showed better results at 0.5% wt. of nanoparticles; and the antiwear mechanism of nanoparticulate additive was produced by tribo-sintering

Viscosity and tribology of copper oxide nanofluids

Nanofluids, a term proposed by Choi in 1995 [1], are composites consisting of solid nanoparticles with sizes varying generally from 1 to 100 nm dispersed in a liquid. Numerous nanoparticles used as oil additives have been investigated in recent years [2-7]. Results show that they deposit on the rubbing surface and improve the tribological properties of the base oil, displaying good friction and wear reduction characteristics even at concentrations below 2%wt. Although the viscosity of the nanofluids is a property of crucial importance for film forming, and hence friction and wear reduction, which are characteristic of lubricants, only Hwang et al. [8] have studied thermal characteristics, kinematic viscosity and tribological properties of nanofluids simultaneously. In this paper, we present measurements of dynamic viscosity of nanofluids formed by copper oxide nanoparticles dispersed in a polyalphaolefin, for temperatures and concentrations varying from 20 to 60ºC and 0.5 to 2% wt., respectively. Dependence of the nanofluid viscosity to the solid fraction and temperature was compared with existing models and its influence on lubrication was also analysed

Cluster expansion in the canonical ensemble

We consider a system of particles confined in a box \La\subset\R^d interacting via a tempered and stable pair potential. We prove the validity of the cluster expansion for the canonical partition function in the high temperature - low density regime. The convergence is uniform in the volume and in the thermodynamic limit it reproduces Mayer's virial expansion providing an alternative and more direct derivation which avoids the deep combinatorial issues present in the original proof

Cultivation and anaerobic digestion of Scenedesmus spp. grown in a pilot-scale open raceway

Digestibility of a micro-algal mixture was evaluated by mesophilic anaerobic digestion in continuously-stirred tank reactors. The culture consisted primarily of Scenedesmus spp. continuously cultivated over a 6-month period in a 100 m2 raceway reactor instrumented to record pH, dissolved oxygen and temperature. The raceway received supplementary carbon in the form of flue gas from a diesel boiler (10% CO2) injected into a 1-m deep sump to control pH in the range 7.8–8.0. Dilution was optimised to biomass productivity and gave values of 10–15 and 20–25 g total suspended solids (TSS) m? 2 day? 1 in winter (December–February) and spring (April–May), respectively. The culture for the anaerobic digestion trial was harvested in February by centrifugation to give an algal paste containing 4.3% volatile solids (VS). Semi-continuous digestion at organic loading rates of 2.00, 2.75 and 3.50 g VS l? 1 day? 1 gave volumetric biogas productions of ~ 0.66, ~ 0.83 and ~ 0.99 l l? 1 day? 1, respectively. Specific methane yield ranged from 0.13 to 0.14 l CH4 g? 1 VSadded with biogas methane content ~ 62%. Overall the digestion process was stable, but only ~ 30% VS destruction was achieved indicating low biodegradability, due to the short retention times and the recalcitrant nature of this type of biomas

NATURAL AND ANTHROPOGENIC EFFECTS ON THE SOIL GEOCHEMISTRY OF KAVALA AREA, NORTHERN GREECE

A total of 65 surface soils and 8 rock samples from the area surrounding the city of Kavala, Northern Greece, was collected and analyzed for their contents in 10 major and 32 trace elements. The extraction of the elements from the < 200μm soil fraction was based on the digestion of 0.1g of each sample with 2ml HNO3. The analytical methods used were ICP-OES and ICP-MS and the elements determined were Al, Ca, Cl, Fe, K, Mg, Na, P, S, Si, Ag, As, B, Ba, Cd, Ce, Co, nCr, Cs, Cu, Ga, Ge, Hg, La, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Th, Ti, U, V, W, Y, Zn and Zr. Comparisons between the concentrations of the surface soil samples and the surrounding rock samples indicate that the majority of major, as well as, of trace elements are found in the surface soils of Kavala with such concentrations that are considered as the product of natural processes such as the weathering of parent rocks and pedogenesis. However, there are some nmajor elements (Cl, Na, S) and trace elements (Ag, As, Pb, V, Zn) that are present in the surface soils of the study area with elevated concentrations that cannot be regarded as the sole product of natural processes, but as the result of both, natural and anthropogenic activities, especially for the samples that are situated inside the industrial area of Kavala

Vitamin C content of rotifers enriched with the microalga Isochrysis AFF. galbana (T-ISO) collected from different growth conditions.

The aim of our study was to evaluate if different vitamin C contents in T-iso from different growth phases and conditions would lead to correspondingly different vitamin C contents in rotifers enriched with these microalgae.We conclude that the vitamin C content of rotifers can be manipulated by enrichment with cultures of T-iso with different vitamin C content, obtained by different growth conditions. However, special care should be taken to ensure that DW:rotifer ratios in the enrichments do not vary much or are above the ratio when maximum ingestion rates are reached. Acknowledgments: This work was supported by project P08-AGR-3695, Junta de Andaluc&iacute;a, Spain and by Interreg Project ECOAQUA, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.El objetivo de nuestro estudio fue evaluar si los diferentes contenidos de vitamina C en T-iso de diferentes fases y condiciones de crecimiento llevar&iacute;a a diferentes contenidos de vitamina C en los rot&iacute;feros enriquecidos con estas microalgas Nosotros concluimos que el contenido de vitamina C de rot&iacute;feros puede ser manipulado mediante el enriquecimiento con cultivos de T-iso con diferente contenido en vitamina C, obtenidos por diferentes condiciones de crecimiento. Sin embargo, se debe tener especial cuidado para asegurar que en peso seco, las relaciones de rot&iacute;feros en los enriquecimientos no var&iacute;an mucho y est&aacute;n por encima de la tasa cuando se alcanzan los niveles m&aacute;ximos de ingesti&oacute;n. Agradecimientos: Este trabajo fue apoyado por el proyecto P08-AGR-3695, Junta de Andaluc&iacute;a, Espa&ntilde;a y por Interreg EcoAqua proyecto, financiado por el FEDER (Fondo Europeo de Desarrollo Regional). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.</p

Horner's Syndrome due to a Spontaneous Internal Carotid Artery Dissection after Deep Sea Scuba Diving

Internal carotid artery dissection (ICAD) is a rare entity that either results from traumatic injury or can be spontaneously preceded or not by a minor trauma such as sporting activities. It represents a major cause of stroke in young patients. The diagnosis should be suspected with the combination of Horner''s syndrome, headache or neck pain, and retinal or cerebral ischaemia. The confirmation is frequently made with a magnetic resonance angiography (MRA). Although anticoagulation with heparin followed by vitamin-K-antagonists is the most common treatment, there is no difference in efficacy of antiplatelet and anticoagulant drugs at preventing stroke and death in patients with symptomatic carotid dissection. We describe a patient with ICAD following deep sea scuba diving, who presented with Horner''s syndrome and neck pain and was successfully treated with anticoagulants

NALP1 is a transcriptional target for cAMP-response-element-binding protein (CREB) in myeloid leukaemia cells

NALP1 (also called DEFCAP, NAC, CARD7) has been shown to play a central role in the activation of inflammatory caspases and processing of pro-IL1β (pro-interleukin-1β). Previous studies showed that NALP1 is highly expressed in peripheral blood mononuclear cells. In the present study, we report that expression of NALP1 is absent from CD34+ haematopoietic blast cells, and its levels are upregulated upon differentiation of CD34+ cells into granulocytes and to a lesser extent into monocytes. In peripheral blood cells, the highest levels of NALP1 were observed in CD3+ (T-lymphocytes), CD15+ (granulocytes) and CD14+ (monocytes) cell populations. Notably, the expression of NALP1 was significantly increased in the bone marrow blast cell population of some patients with acute leukaemia, but not among tissue samples from thyroid and renal cancer. A search for consensus sites within the NALP1 promoter revealed a sequence for CREB (cAMP-response-element-binding protein) that was required for transcriptional activity. Moreover, treatment of TF1 myeloid leukaemia cells with protein kinase C and protein kinase A activators induced CREB phosphorylation and upregulated the mRNA and protein levels of NALP1. Conversely, ectopic expression of a dominant negative form of CREB in TF1 cells blocked the transcriptional activity of the NALP1 promoter and significantly reduced the expression of NALP1. Thus NALP1 is transcriptionally regulated by CREB in myeloid cells, a mechanism that may contribute to modulate the response of these cells to pro-inflammatory stimuli

Corrosion activity and solubility in polar oils of three bis(trifluoromethylsulfonyl) imide/bis(trifluoromethylsulfonyl) amide ([NTF2]) anion-based ionic liquids.

The corrosion behaviour and solubility of three bis(trifluoromethylsulfonyl)amide1 ([NTf2]) anion-based ionic liquids: 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C12MIM][NTf2]), tributylmethylammonium bis(trifluoromethylsulfonyl)amide ([N4441][NTf2]), and methyltrioctylammonium bis(trifluoromethylsulfonyl)amide ([N1888][NTf2]), as a component in a mixture with different base oils were analysed. Six polar oils suitable for use in lubrication were utilized as base oil. Solubility tests were performed by using turbidimetry, and corrosion was checked at 4 v/v% by examining the roughness and chemical composition of the surface after 21 days. The results showed that long carbon chains in the cation improve the solubility greatly in diesters and slightly in polyolesters. Corrosion was not detected at this concentration