Effect of Reciprocation Frequency on Friction and Wear of Vibrating Contacts Lubricated with Soybean-Based B100 Biodiesel

The use of renewable, bio-based fuels has become increasingly widespread in recent years, with a major example being biodiesel, a bio-derived alternative to Number 2 diesel fuel. The increased usage of biodiesel gives rise to an augmented need to understand its tribological effects on critical engine components. This study focused on determining the tribological performance of soybean-based B100 (i.e., pure) biodiesel within a fuel injector with varying oscillating frequency by performing a series of linear reciprocating tribological tests of biodiesel-lubricated interfaces with varying reciprocating frequency. Comparison of friction coefficient variation with reciprocating frequency indicated a transition from boundary lubrication to hydrodynamic lubrication as the frequency increased, while hysteresis loop and energy loss observations showed a transition between full stick and partial slip contact with increasing frequency. However, observations of induced wear showed the wear to increase with increasing frequency, most likely due to the augmented number of sliding cycles as well as an increased degree of interfacial slip.     

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Whilst there have been numerous categorisations of high-rise buildings according to their function, architectural style, height or structural strategy, historically little work has been undertaken to classify them based on factors affecting their energy performance — their shape and form, façade, attitude to natural lighting, ventilation strategies, etc. These factors have been influenced by regulatory changes, developments in technology and materials, changes in architectural thinking and economic and commercial drivers. Developments such as the New York Zoning Law of 1916, the postwar innovations in curtain wall façades and the energy crises of the 1970s have all impacted on the way tall buildings of the time were designed and operated. These events also had a significant impact on the quantity of energy and the way in which it was consumed in tall buildings of the time. This paper examines the history of energy use in tall buildings, from their origins in North America in the late nineteenth century to the present day. In doing so, it categorises tall buildings into five chronological ‘generations’, based on their energy consumption characteristics.     

On the Cooling Rate-Microstructure Relationship in Molten Metal Gas Atomization

Metallurgical and Materials Transactions A - Gas atomization is the most used powder production technique since it provides good control on particles shape, surface oxidation and dimension. It is a...     

Self-nucleation of isotactic poly(1-butene) in the trigonal modification

Isotactic poly(1-butene) (i-PBu) is a polyolefin of industrial relevance which exhibits an interesting polymorphism. Upon cooling from the relaxed melt at atmospheric pressure, a tetragonal phase (Form II) develops. However, being metastable, this structure slowly evolves upon aging in the stable trigonal modification (Form I). Another trigonal modification, denoted Form I′, can also crystallize directly from the melt if proper conditions are met, e.g., high pressure, low tacticity, ultrathin samples etc. In this work, we aim to verify whether, by acting on the nucleation stage via a proper thermal history, the direct formation of the trigonal polymorph from the melt in a bulk sample is possible. Nucleation of i-PBu has been tailored by means of the self-nucleation technique, imposed on previously aged samples (Form I). DSC and temperature-resolved WAXS show that different crystallization pathways can be observed, depending on the residual concentration of Form I self-nuclei. With decreasing self-nucleation temperature we first encounter “cross-nucleation” of the tetragonal crystal on trigonal nuclei, followed by concomitant crystallization of Form II and Form I′ and eventually the sole formation of the trigonal modification (Form I′).     

聚酯瓶回收(水洗)

聚酯瓶使用的大量增加使得全世界范围内对于作为替代原生材料的二次原料——再生聚酯瓶片的回收及使用产生愈加浓厚的兴趣。     

Validation of a 1-Day Analytical Diagnostic Real-Time PCR for the Detection of Salmonella in Different Food Meat Categories

Foodborne disease caused by Salmonella represents a worldwide public health problem. In Europe, salmonellosis is still the second most commonly recorded zoonosis. Since the standard culture method for detecting Salmonella (ISO 6579:2002) requires up to 5 days to produce results, the need to develop rapid methods represents an important issue for the authorities and the producers. The aim of the present study was the in-house validation, according to ISO 16140, of an open-formula diagnostic real-time PCR for the detection of Salmonella in all the different meat categories reported in the EU Regulations relative to microbiological criteria for food safety. The assay employed specific primers and a probe target within the ttrRSBCA locus, which allows the tetrathionate respiration in Salmonella. Selectivity, relative accuracy, relative sensitivity and relative specificity were established by testing 110 bacterial strains and 175 various edible meat samples. Results showed 100 % selectivity, 100 % relative accuracy, 100 % relative sensitivity and 100 % relative specificity of the real-time PCR when compared to the standard culture method used as reference. In addition, in order to minimize the effect of the competitive micro-flora naturally present on meat samples, a highly nutritious and selective commercial medium (ONE Broth Salmonella, Oxoid) was evaluated in comparison with the classical non-selective pre-enrichment broth (buffered peptone water). Results demonstrated that the ONE Broth Salmonella medium increases the growth of Salmonella in the presence of competitive micro-flora.     

Microbes versus microbes: control of pathogens in the food chain

Foodborne illness continues as a considerable threat to public health. Despite improved hygiene management systems and increased regulation, pathogenic bacteria still contaminate food, causing sporadic cases of illness and disease outbreaks worldwide. For many centuries, microbial antagonism has been used in food processing to improve food safety. An understanding of the mode of action of this microbial antagonism has been gained in recent years and potential applications in food and feed safety are now being explored. This review focuses on the potential opportunities presented, and the limitations, of using microbial antagonism as a biocontrol mechanism to reduce contamination along the food chain; including animal feed as its first link. © 2014 Society of Chemical Industry     

Macrobenthos community structural changes off Cesenatico coast (Emilia Romagna, Northern Adriatic), a six-year monitoring programme

Soft bottom macrobenthos at a station located off Cesenatico (Emilia Romagna, Northern Adriatic Sea) was investigated seasonally for six years from July 1996 to July 2002. Species composition and abundance of the community have been studied in relation to fluctuation in the water environment parameters, sediment texture patterns and mucilage, that occurred mainly in the water column at the study site. Three major Po river flow peaks occurred in November 1996, October 2000 and May 2002; after these events the community was reduced to minimum abundance values (total density<2000 individuals m(-2)). In the period between the first two episodes the river discharge remained rather low and conditions of increased salinity, lower nutrients and chl a and good oxygen saturation were experienced. The fossorial Crustacean Ampelisca diadema became dominant in the community between the first two river flow events, reaching maximum density of 10,200 individuals m(-2) and substituting the bivalve Corbula gibba, indicator of sediment instability. Species richness increased in the same period. The role of Ampelisca as a facilitator in structuring the community is discussed. Corbula gibba never recovered to initial densities, apart from an abundance peak that occurred in the summer of 2000. Faunal composition seemed to evolve slowly towards a higher degree of structural complexity (positive trend in diversity and evenness index). In the study site near-bottom mucilage events occurred in the summers of 1997, 1998, 2002; they appeared uncorrelated with the observed changes in the community structure. Multivariate analysis of community structure (MDS, ANOSIM) illustrates that community changes in this station are driven mainly by hydrographical conditions influencing sediment texture patterns and trophic resources for the benthos.