A comparative study on the jet loop reactor and continuos stirred tank reactor in the selective hydrogenation of palm olein (I.V.64)

Jet Loop Reactor (JLR) was developed to improve the overall performance of hydrogenation processes. Nevertheless, the application of JLR in the palm oil and oleochemical industries in Malaysia is still very much sparse. A substantial amount of investment and the lack of study conducted in Malaysia on the application of JLR have retarded the retrofitment and/or replacement of the conventional CSTR with this technology. In the wake of this, a comparative study was conducted to investigate the performance of JLR in the selective hydrogenation of palm olein with an IV of 64 in comparison to the hydrogenation in the conventional CSTR system. A pilot scale JLR with a capacity of 250 liter was used in the study. The circulation of the sample in the loop was achieved via a single speed pump. The experimental result was compared with result from the CSTR experiment. A down-scaled laboratory CSTR apparatus was used in the study for this purpose. A software package, developed via Microsoft Excel 2000 and Visual Basic Application (VBA) softwares, was used to simulate the behavior of the hydrogenation process in both, JLR and CSTR, under similar capacity. The outcome of the study showed that with the limitation of single speed pump, the JLR could not matched the superiority of CSTR in the selective hydrogenation process for it required slow reaction to produce high trans fatty acids hydrogenated product. On the positive note, the developed software package is a useful tool which allows an easy method to study the behavior of the hydrogenation process of JLR and CSTR. The prediction of the CSTR process was acceptable, but the prediction of JLR process was less accurate, revealing a maximum of 30% error. It can be concluded that the present analytical method used in the simulation of JLR required improvement on the modeling of the process, or to opt for the numerical solution, to produce a much better prediction. A retrofit method was also suggested in the study, for the possibility of fitting in the JLR facility in the existing CSTR system with minimal modification, for the system to have dual function of slow and fast reactions

The Importance of Physical Models for Deriving Dust Masses and Grain Size Distributions in Supernova Ejecta I: Radiatively Heated Dust in the Crab Nebula

Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly-condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula (PWN). We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 solar masses, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 microns. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP SN. Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium (ISM) and in external galaxies.Comment: 9 pages, 2 tables, 8 figures, Accepted to The Astrophysical Journa

Larval parasitism of the autumnal moth reduces feeding intensity on the mountain birch

Plants respond to grazing by herbivorous insects by emitting a range of volatile organic compounds, which attract parasitoids to their insect hosts. However, a positive outcome for the host plant is a necessary precondition for making the attraction beneficial or even adaptive. Parasitoids benefit plants by killing herbivorous insects, thus reducing future herbivore pressure, but also by curtailing the feeding intensity of the still living, parasitised host. In this study, the effect of parasitism on food consumption of the 5th instar larvae of the autumnal moth (Epirrita autumnata) was examined under laboratory conditions. Daily food consumption, as well as the duration of the 5th instar, was measured for both parasitised and non-parasitised larvae. The results showed that parasitism by the solitary endoparasitoid Zele deceptor not only reduced leaf consumption significantly but also hastened the onset of pupation in autumnal moth larvae. On the basis of the results, an empirical model was derived to assess the affects on the scale of the whole tree. The model suggests that parasitoids might protect the tree from total defoliation at least at intermediate larval densities. Consequently, a potential for plant–parasitoid chemical signalling appears to exist, which seems to benefit the mountain birch (Betula pubescens ssp. czerepanovii) by reducing the overall intensity of herbivore defoliation due to parasitism by this hymenopteran parasitoid

Co-occurrence of risky lifestyle behavior with overweight, excess abdominal fat and high blood pressure - case oriented approach [Zajednička pojavnost rizičnog ponašanja i prekomjerne tjelesne težine, abdominalne debljine i visokog tlaka - studija slučajeva]

The objective was to estimate the proportion of cases developed interim risk factors (INTF: overweight, excess abdominal fat, high blood pressure) in relation with behavioral risk factors (BEHF: smoking, heavy alcohol intake, unhealthy diet, physical inactivity). NOBIR group was defined as cases with no BEHF and BIR as those with them. Both groups show higher proportions of INTF in older age. The increase by age varies of twofold (overweight: 13.2-29.2 for men, 18.1-42.6 for women) to six fold (high blood pressure: 4.6-26.5 for men, 6.6-40.8 for women) in proportions. Women show higher proportions of INTF than men in both groups, but BIR group shows higher proportions than NOBIR in all the age groups taking the both gender together. As a BEHF the physical inactivity has a markedly increase with age (from 4% to more than 25%). Smoking is the only BEHF decreasing in oldest for all the INTF

Expansion of the winter moth outbreak range : no restrictive effects of competition with the resident autumnal moth

1. Both direct and indirect competition can have profound effects on species abundance and expansion rates, especially for a species trying to strengthen a foothold in new areas, such as the winter moth (Operophtera brumata) currently in northernmost Finland. There, winter moths have overlapping outbreak ranges with autumnal moths (Epirrita autumnata), who also share the same host, the mountain birch (Betula pubescens ssp. czerepanovii). Competitive interactions are also possible, but so far unstudied, are explanations for the observed 1–3 years phase lag between the population cycles of the two moth species. 2. In two field experiments, we studied host plant-mediated indirect inter-specific competition and direct interference/exploitation competition between autumnal and winter moths. The experimental larvae were grown either with the competing species or with the same number of conspecifics until pupation. Inter-specific competition was judged from differences in pupal mass (reflecting lifespan fecundity), larval development time and larval survival. 3. Larval performance measurements suggested that neither direct nor indirect interspecific competition with the autumnal moth reduce the growth rate of winter moth populations. Winter moths even had a higher probability of survival when reared together with autumnal moths. 4. Thus, we conclude that neither direct nor indirect inter-specific competition is capable of suppressing the spread of the winter moth outbreak range and that both are also an unlikely cause for the phase lag between the phase-locked population cycles of the two moth species