Plant oils as fuels for compression ignition engines: a technical review and life-cycle analysis

As an alternative fuel for compression ignition engines, plant oils are in principle renewable and carbon-neutral. However, their use raises technical, economic and environmental issues. A comprehensive and up-to-date technical review of using both edible and non-edible plant oils (either pure or as blends with fossil diesel) in CI engines, based on comparisons with standard diesel fuel, has been carried out. The properties of several plant oils, and the results of engine tests using them, are reviewed based on the literature. Findings regarding engine performance, exhaust emissions and engine durability are collated. The causes of technical problems arising from the use of various oils are discussed, as are the modifications to oil and engine employed to alleviate these problems. The review shows that a number of plant oils can be used satisfactorily in CI engines, without transesterification, by preheating the oil and/or modifying the engine parameters and the maintenance schedule. As regards life-cycle energy and greenhouse gas emission analyses, these reveal considerable advantages of raw plant oils over fossil diesel and biodiesel. Typical results show that the life-cycle output-to-input energy ratio of raw plant oil is around 6 times higher than fossil diesel. Depending on either primary energy or fossil energy requirements, the life-cycle energy ratio of raw plant oil is in the range of 2–6 times higher than corresponding biodiesel. Moreover, raw plant oil has the highest potential of reducing life-cycle GHG emissions as compared to biodiesel and fossil diesel.

Health related quality of life and perception of stigmatisation in adolescents living with sickle cell disease in Nigeria:a cross sectional study

Background: Sickle cell disease impacts the physical, emotional and psychological aspects of life of the affected persons, often times exposing them to disease associated stigma from the society and alters the health related quality of life (HRQoL). This study compared the HRQoL of adolescents with sickle cell disease with their healthy peers, identified socio-demographic and clinical factors impacting HRQoL, and determined the extent and effects of SCD related stigma on quality of life. Procedure: We conducted a cross-sectional survey among 160 adolescents, 80 with SCD and 80 adolescents without SCD. Socio-demographic and clinical data were collected using a pre-tested questionnaire. HRQoL was investigated using the Short Form (SF-36v2) Health Survey. SCD perceived stigma was measured using an adaptation of a perceived stigma questionnaire. Results: Adolescents with SCD have significantly worse HRQoL than their peers in all of the most important dimensions of HRQoL (physical functioning, physical roles limitation, emotional roles limitation, social functioning, bodily pain, vitality and general health perception) except mental health. Recent hospital admission and SCD related complication further lowered HRQoL scores. Over seventy percent of adolescents with SCD have moderate to high level of perception of stigmatisation. Hospitalisation, SCD complication, SCD stigma were inversely, and significantly associated with HRQoL. Conclusions: Adolescents living with SCD in Nigeria have lower health related quality of life compared to their healthy peers. They also experience stigma that impacts their HRQoL. Complications of SCD and hospital admissions contribute significantly to this impairment. Pediatr Blood Cancer 2015;62:1245-1251.

A model for the modular evolution of rna addressing open questions on the origin of life

A main unsolved problem in the RNA world scenario for the origin of life is how a template-dependent RNA polymerase ribozyme emerged from short RNA oligomers generated by random polymerization of ribonucleotides (Joyce and Orgel 2006). Current estimates establish a minimum size about 165 nt long for such a ribozyme (Johnston et al. 2001), a length three to four times that of the longest RNA oligomers obtained by random polymerization on clay mineral surfaces (Huang and Ferris 2003, 2006). To overcome this gap, we have developed a stepwise model of ligation-based, modular evolution of RNA (Briones et al. 2009) whose main conceptual steps are summarized in Figure 1. This scenario has two main advantages with respect to previous hypotheses put forward for the origin of the RNA world: i) short RNA....