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

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

Responses of generalist invertebrate predators to pupal densities of autumnal and winter moths under field conditions

1. Generalist natural enemies are usually not considered as being capable of causing population cycles in forest insects, but they may influence the population dynamics of their prey in the low density cycle phase when specialist enemies are largely absent. 2. In the present field study, the total response of the generalist invertebrate predator community to experimentally established pupal densities of the closely related autumnal (Epirrita autumnata) and winter moths (Operophtera brumata) was analysed. 3. Due to the high amount of variation in the dataset, the exact shape of the response curve could not be convincingly estimated. Nevertheless, two important conclusions can be drawn from the analyses. 4. Firstly, the natural invertebrate predator community seems to become saturated at rather low densities of both autumnal and winter moth pupae. Secondly, the predator community seems to become saturated at much lower densities of autumnal than of winter moth pupae. 5. Furthermore, pupal mass was significantly negatively correlated with invertebrate predation probability in autumnal moth pupae. 6. These results indicate that differences in the predator assemblage being able to consume pupae of the two moth species, as well as different handling times, could be responsible for the substantially higher predation rates in winter than in autumnal moth pupae. 7. As a consequence, the population dynamics of autumnal moths might be less affected by generalist invertebrate predators than those of winter moths, as autumnal moths seem able to escape from the regulating influence of generalist predators at much lower population densities than winter moths

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

The free energy of biomembrane and nerve excitation and the role of anesthetics

In the electromechanical theory of nerve stimulation, the nerve impulse consists of a traveling region of solid membrane in a liquid environment. Therefore, the free energy necessary to stimulate a pulse is directly related to the free energy difference necessary to induce a phase transition in the nerve membrane. It is a function of temperature and pressure, and it is sensitively dependent on the presence of anesthetics which lower melting transitions. We investigate the free energy difference of solid and liquid membrane phases under the influence of anesthetics. We calculate stimulus-response curves of electromechanical pulses and compare them to measured stimulus-response profiles in lobster and earthworm axons. We also compare them to stimulus-response experiments on human median nerve and frog sciatic nerve published in the literature.Comment: 10 pages, 6 figure

Population genetic structure and phylogeography of invasive aquatic weed, Elodea canadensis (Hydrocharitaceae) and comparative analyses with E. nuttallii

The introductions of invasive species are one of the most important threats to global biodiversity and ecosystem function. In addition, invasive species often cause large economical and social consequences. Genetic characteristics of introduced populations have an impact on their capacity of range expansion in the non-native areas. Therefore, understanding the evolutionary consequences of invasions will provide knowledge for the design of appropriate methods for managing introduced populations. In addition, detailed genetic data enables the design of molecular genetic markers useful in monitoring risky species and in early detection of new invasions. In this thesis, I developed novel genetic markers to investigate population genetic structure and phylogeography of two invasive aquatic weeds, Elodea canadensis Michx and E. nuttallii (Planch.) St. John (Hydrocharitaceae). I investigated the genetic population structure of introduced Finnish E. canadensis populations using microsatellite markers. The results revealed a moderate level of variation within and among Finnish populations analysed. Despite of the genetic variation detected, the possibility of only one introduction followed by post-establishment evolution cannot be rejected based on the results in this thesis. Furthermore, I surveyed the geographical distribution of the chloroplast (cp) DNA haplotypes within the native and introduced ranges of E. canadensis and E. nuttallii in order to reconstruct the spreading histories of these species. Only a single haplotype was found in the introduced range in both species and these haplotypes were widespread also in the native range. Therefore, I was not able to identify the geographic origin of the introduced populations or test the hypothesis of single versus multiple introductions. I sequenced the complete cp genome sequence and characterized the cp genome organization of E. canadensis. The results showed that the cp genome of E. canadensis has gone through less rearrangements or gene losses when compared to assumed ancestral species than have the other monocots studied. The inverted repeat region (IR) of E. canadensis has a unique structure among the monocot species studied so far. Only few cp genomes representing early lineages of monocots have been sequenced and, therefore, this thesis provides valuable information about the course of evolution in the divergence of monocot lineages. This thesis addresses key issues in the biology of invasive species and gives novel information on the genetic patterns at native and introduced populations of E. canadensis and E. nuttallii. It also provides a source of genetic markers for future investigations of the population genetics of invasive species. The results highlight the need for further investigation of the Elodea species, as well as studies on other invasive plant species. Future research should focus on predictive analyses of potential future invaders and other preventive methods to minimize new introductions.Haitalliset vieraslajit ovat maailmanlaajuisesti yksi suurimmista uhkatekijöistä luonnon monimuotoisuudelle. Vieraslajeilla on usein lisäksi taloudellisia, terveydellisiä ja sosiaalisia vaikutuksia. Molekyylimenetelmien avulla voidaan kerätä tärkeää tietoa vieraslajien populaatioiden geneettisestä rakenteesta. Menetelmillä voidaan myös tutkia vieraslajien leviämisreittejä ja leviämisen alkuperää. Molekyylimenetelmät voivat toimia myös lajintunnistuksen apuvälineinä, joilla voidaan tehokkaasti tarkkailla potentiaalisten vieraslajien populaatioita ja havaita ajoissa uudet invaasiot. Näitä tietoja voidaan hyödyntää, kun pohditaan menetelmiä vieraslajipopulaatioiden hallintaan ja pyritään estämään uusia invaasioita. Tämän väitöstutkimuksen kohteena olivat kanadanvesirutto (Elodea canadensis) ja kiehkuravesirutto (E. nuttallii), jotka ovat Pohjois-Amerikasta kotoisin olevia vesikasvilajeja. Kumpikin vesiruttolaji on levinnyt alkuperäisalueiltaan Eurooppaan ja muille mantereille ja muodostaa uusilla kasvupaikoillaan massakasvustoja. Kasvustot voivat syrjäyttää alkuperäislajeja sekä aiheuttaa muutoksia vesistön happamuus- ja ravinnetasossa. Lisäksi massakasvustot vaikeuttavat vesistöjen virkistyskäyttöä. Kanadanvesirutto aiheuttaa ongelmia myös monissa Suomen vesistöissä. Kiehkuravesirutto on levinnyt suureen osaan Eurooppaa ja sen arvellaan leviävän lähivuosina myös Suomeen. Kehitin väitöstutkimuksessani tuman DNA:n molekyylimerkkejä, joiden avulla tutkin kanadanvesiruton geneettistä populaatiorakennetta Suomen tulokaspopulaatioissa ja selvitin lajin leviämishistoriaa Suomessa. Lisäksi selvitin kanadanvesiruton kloroplastigenomin DNA:n emäsjärjestyksen ja kehitin kloroplastin DNA:n molekyylimerkkejä, joiden avulla tutkin kanadanvesiruton ja kiehkuravesiruton populaatioita laajasti alkuperäis- ja tulokasalueilla. Tarkoituksenani oli selvittää geneettisen muuntelun maantieteellistä jakautumista ja lajien tulokaspopulaatioiden mahdollista alkuperää. Tutkimustulokset osoittavat, että Suomen kanadanvesiruttopopulaatioissa esiintyy kohtuullinen määrä muuntelua. Näiden tulosten perusteella ei kuitenkaan voida päätellä, onko laji levinnyt Suomeen useita kertoja. On mahdollista, että geneettinen muuntelu on seurausta yhden invaasion jälkeen seuranneesta nopeasta evolutiivisesta muutoksesta tulokaspopulaatioissa. Tutkittaessa geneettisen muuntelun maantieteellistä jakautumista löydettiin yhteensä kolme kanadanvesiruton ja neljä kiehkuravesiruton haplotyyppiä. Molemmilla lajeilla havaittiin yksi valtahaplotyyppi, joka kattaa suurimman osan alkuperäisalueesta ja kaikki populaatiot uusilla kasvupaikoilla. Euroopan tulokaspopulaatiot saattavat olla peräisin yhdestä tai useammasta invaasiosta, jotka edustavat samaa haplotyyppiä. Tulokset osoittavat lisäksi, että kanadanvesiruton kloroplastigenomin rakenne on hyvin samankaltainen kuin alkukantaisilla putkilokasveilla ja eroaa kaikista tähän mennessä tutkituista yksisirkkaisista kasvilajeista. Siten tutkimus tuo uutta tietoa yksisirkkaisten evoluutiosta. Osa tutkimuksessa kehitetyistä molekyylimerkeistä toimii tehokkaina työkaluina vesiruttolajien välisessä lajintunnistuksessa ja on siten apuna uusien invaasioiden varhaisessa havainnoinnissa. Tämä väitöstutkimus tuo lisätietoa vieraslajien biologian keskeisistä tutkimuskysymyksistä. Tulokset kuitenkin osoittavat, että lisäselvitykset ovat tarpeen. Lisäksi tarvitaan käytännön toimia, sillä biologisen tutkimuksen avulla ei voida ratkaista kaikkia vieraslajeihin liittyviä ongelmia. Tulevaisuudessa tutkimuksen tulisi keskittyä erityisesti vieraslajien leviämisen ennaltaehkäisevään torjuntaan ja uusien invaasioiden mahdollisimman varhaisen havaitsemisen tehostamiseen