Effects of Temperature Changes, Air Velocities and Volume Fractions on the Single Droplet Evaporation Behaviors at High Ambient Temperatures / W. Manosroi

This study is aimed to investigate the effects of temperature changes and air velocities on the evaporation behaviors of the single droplet single component (pentadecane C-15) and binary mixtures (pentadecane C-15 and dodecane C-12 at 3:1, 1:1 and 1:3 volume ratios) in a heated chamber at high ambient temperatures of 91-98, 110-118, 129-145 and 155-170°C. The effects of volume fractions on the binary mixture single droplet evaporation characterisitics are also evaluated. The droplet diameter is measured at the forward scattering region. The time dependent changes of the droplet diameters are calculated from the Morphology Dependent Resonances (MDRs) of the refractive index which are measured in the backward region. The evaporation rates of the droplet increased with increased ambient temperatures. There is no effect of ambient air velocities on the droplet evaporation rates, owing to the small relative velocities between the droplets and the air. For the single component droplets, the ambient temperature is the most influent parameter on droplet evaporation rates and evaporation rate changes. For the binary mixture droplets, the volume fraction is the most influent parameter on droplet evaporation rates and evaporation rate changes. The results from this study can be applied for a better understanding of the fuel droplet in the combustion chamber of the engines

An improved size and refractive index measurement of a pentadecane single droplet in a heated chamber

The pentadecane single droplet size of less than 20 µm and its refractive index were measured at various ambient temperatures of 100, 120, 150 and 180 °C. The experimental setup was equipped with the high speed linear CCD camera to give sharp and clearly visible MDRs (Morphology Dependent Resonances) structure from the droplet refractive index. The valve of the heated chamber was closed during the experiment until the droplet disappeared from the chamber to increase the measurement time of about 2 folds in order to obtain more experimental data of the droplet behaviors. The cooling device was mounted on the heated chamber to improve boundary condition and smooth the ambient temperature. The obtained droplet sizes were in good agreement with both the D2 law and the Rapid Mixing Model (RMM), while the measured droplet refractive index values were closed to those calculated from the previous reported formula. This has indicated the reliability and applicability of this improved measurement technique for a better understanding of the real fuel droplet behaviors in a combustion system

Protective effects of solvent fractions of Mentha spicata (L.) leaves evaluated on 4-nitroquinoline-1-oxide induced chromosome damage and apoptosis in mouse bone marrow cells

Spearmint leaves (Mentha spicata L.) contain high levels of antioxidants that are known to protect against both exogenous and endogenous DNA damage. In this study, the protective effects of the hexane fraction (HF), chloroform fraction (CF) and ethyl acetate fraction (EAF) in an ethanol extract from M. spicata were evaluated against 4-nitroquinoline-1-oxide (4-NQO) induced chromosome damage and apoptosis in bone marrow cells of Swiss albino mice. Two (EAF; 80 and 160 mg/ kg body weight - bw) or three (HF and CF; 80, 160 and 320 mg/ kg bw) doses of solvent fractions or vehicle control (25% DMSO in water) were administered orally for five consecutive days. Upon the sixth day, 4-NQO was injected intraperitoneally. The animals were killed the following day. Other control groups were comprised of animals treated with either the vehicle control or the various doses of solvent fractions, but with no 4-NQO treatment. 4-NQO induced micro-nucleated polychromatic erythrocytes (MnPCEs) in all the test groups. However, pre-treatment of animals with the solvent fractions significantly reduced the 4-NQO-induced MnPCEs as well as the percentage of apoptotic cells. The reduction of both MnPCE and apoptosis was more evident following the pre-treatment of animals with 160 mg/kg bw EAF

Cytogenetic analysis of three sea catfish species (Teleostei, Siluriformes, Ariidae) with the first report of Ag-NOR in this fish family

Despite their ecological and economical importance, fishes of the family Ariidae are still genetically and cytogenetically poorly studied. Among the 133 known species of ariids, only eight have been karyotyped. Cytogenetic analyses performed on Genidens barbus and Sciades herzbergii revealed that both species have 2n = 56 chromosomes and Cathorops aff. mapale has 2n = 52 chromosomes: Genidens barbus has 10 Metacentrics (M), 14 Submetacentrics (SM), 26 Subtelocentrics (ST), and 6 Acrocentrics (A), Sciades herzbergii has 14M, 20SM, 18ST and 4A, whereas Cathorops aff. mapale has 14M, 20SM, and 18ST. The nucleolus organizer regions (NORs) were found in a single chromosome pair on the short arm of a large-sized ST pair in Genidens barbus and on the short arm of a middle-size SM pair in Cathorops aff. mapale. Multiple NORs on the short arms of two large-sized ST pairs were found in Sciades herzbergii. The occurrence of diploid numbers ranging from 2n = 52 through 56 chromosomes and the presence of different karyotypic compositions, besides the number and position of NORs suggest that several numeric and structural chromosome rearrangements were fixed during the evolutionary history of this fish family

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

Abstract Scrub typhus, caused by Orientia tsutsugamushi, is an important and neglected vector-borne zoonotic disease with an expanding known distribution. The ecology of the disease is complex and poorly understood, impairing discussion of public health interventions. To highlight what we know and the themes of our ignorance, we conducted a systematic review of all studies investigating the pathogen in vectors and non-human hosts. A total of 276 articles in 7 languages were included, with 793 study sites across 30 countries. There was no time restriction for article inclusion, with the oldest published in 1924. Seventy-six potential vector species and 234 vertebrate host species were tested, accounting for over one million trombiculid mites (‘chiggers’) and 83,000 vertebrates. The proportion of O. tsutsugamushi positivity was recorded for different categories of laboratory test and host species. Vector and host collection sites were geocoded and mapped. Ecological data associated with these sites were summarised. A further 145 articles encompassing general themes of scrub typhus ecology were reviewed. These topics range from the life-cycle to transmission, habitats, seasonality and human risks. Important gaps in our understanding are highlighted together with possible tools to begin to unravel these. Many of the data reported are highly variable and inconsistent and minimum data reporting standards are proposed. With more recent reports of human Orientia sp. infection in the Middle East and South America and enormous advances in research technology over recent decades, this comprehensive review provides a detailed summary of work investigating this pathogen in vectors and non-human hosts and updates current understanding of the complex ecology of scrub typhus. A better understanding of scrub typhus ecology has important relevance to ongoing research into improving diagnostics, developing vaccines and identifying useful public health interventions to reduce the burden of the disease.</jats:p