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A new preparation scheme of few-layer graphene water nanofluids was developed by exfoliating graphite in water with the help of polymer. The approach used centrifugation to classify the graphene nanosheets that made the graphene nanoflake length controllable. Population balance model was used to study the mechanism of exfoliation of graphite and the results revealed that the abrasion, cleavage and fracture all happened in these different stages of the exfoliation process. Mechanisms behind the size selection were also discussed and the terminal velocity was the critical factor to control the flake length. A simple model was developed to guide future similar experiments to obtain desired length graphene nanofluids. The stability of graphene nanofluid was also investigated and the result revealed that the obtained nanofluid showed enhanced stability suggesting great potential in heat transfer applications. [ABSTRACT FROM AUTHOR]

Social fish raised in farms are usually kept in groups of similar-sized individuals. However, social animals of similar size typically have similar fighting ability, which increases aggressive interaction for social rank establishment, as well as social stress. We compared Thai strain Nile tilapia fish,Oreochromis niloticus(L.), held under two treatments: (1) The Homogeneous one, with five adult male fish of similar size and (2) the Heterogeneous treatment with five adult males of different sizes. We recorded the frequency of aggressive interactions and checked social stability and stress levels (cortisol) after five days in the groups. Grouping similar sized Thai Nile tilapia increased the aggressive interactions and delayed rank stability with increased body injuries as a consequence. Homogeneous-sized individuals showed a similar level of stress while heterogeneous-sized individuals showed different stress levels with dominants being more stressed than subordinates. The data indicate that the practice of selecting fish of similar size in aquaculture management could reduce the welfare of social fish and that the effect is observed in different lineages. [ABSTRACT FROM PUBLISHER]

In 2001 and 2002 we studied Eurasian otter (Lutra lutra) fish selection in southern Italy by comparing otter diet (805 analysed spraints) with fish availability, estimated by electrofishing. The surveyed river was dominated by cyprinids, particularly by chub (Leuciscus cephalus), roach (Rutilus rubilio) and bleak (Alburnus sp.). Roach and chub were the most common prey recorded in spraints. Otters ate mainly small prey (total length < 90 mm). Chub were widely consumed according to abundance, whilst roach and bleak consumption was not proportionate to their availability. Otters selected roach both in 2001 and 2002 and responded to a decrease in roach availability (-27.3%) by increasing their frequency of consumption rather than switching to an alternative prey. Despite their high abundance, bleak seemed to be markedly avoided by otters. We hypothesized that differences in microhabitat selection may influence the susceptibility of cyprinids to otter predation. The possible effects on fish community were briefly discussed. [ABSTRACT FROM AUTHOR]

Abstract: Ultrafine gold and nickel nanoparticles (NPs) were fabricated by pulsed laser ablation in helium gas, and the NPs 2–15nm in diameter were selectively classified by an electrostatic size-selection technique employing a low-pressure differential mobility analyzer (LP-DMA). In the classification of the NPs, a chain of several gold NPs or doubly charged NPs were produced as well as singly charged spherical NPs. The morphological selection was performed with the LP-DMA, using a relationship in which the cross section of the spherical NP chains was governed by the product of the diameter and the length, instead of by the square of the diameter. Below a blocking temperature of about 100K, the Ni NPs that were 3.1nm in diameter exhibited ferromagnetism. [Copyright &y& Elsevier]