Hydrodynamics Characteristics and Gas-Liquid Mass Transfer in a Three Phase Fluidized Bed Reactor

This paper presents the experimental characterization of hydrodynamics and gas-liquid mass transfer in a three-phase fluidized bed containing polystyrene and nylon particles. The influence of gas and liquid velocities on phase holdups and volumetric gas-liquid mass transfer coefficient was investigated for flow conditions similar to those applied in biotechnological process. The phase holdups were obtained by the pressure profile technique. The volumetric gas-liquid mass transfer coefficient was obtained adjusting the experimental concentration profiles of dissolved oxygen in the liquid phase with the predictions of the axial dispersion model. According to experimental results the liquid holdup increases with the gas velocity, whereas the solid holdup decreases. The gas holdup increases significantly with the increase in gas velocity, and it shows for the three-phase fluidized bed comparable values or larger than those of bubble column. The volumetric gas-liquid mass transfer coefficient increases significantly with an increase in the air velocity for both bubble column and fluidized beds. In addition, in the operational condition of high liquid velocity, the presence of low-density particles in the bed increased the gas-liquid mass transfer, and thus the volumetric mass transfer coefficient values obtained in the fluidized bed were comparable or larger than those of bubble column.

Potential for seed bank formation of two weed species from Brazilian Amazonia

The potential for seed bank formation of two perennial weed species, Ipomoea asarifolia (Desr.) Roem. & Schult. (Convolvulaceae) and Stachytarpheta cayennensis (Rich.) M. Vahl (Verbenaceae), both common in Amazonia , was evaluated in a degraded pasture area in eastern Brazilian Amazonia . Seeds were enclosed in nylon mesh packets and placed at the soil surface or buried at 5 or 10 cm deep. The number of viable seeds was recorded at 6, 10, 14 and 18 months after burial. Results showed that S. cayennensis has the ability to form persistent soil seed bank, while I. asarifolia seeds do not build up in the soil seed bank. For S. cayennensis and, to some extent, for I. asarifolia, seed survival was highest at greater burial depths.

Lehmästä leopardiin : eläinlääkärityön muistoja

Kirjallisuusarvostelu

Variation between three Eremanthus (Asteraceae) species in their ability to form a seed bank

Knowledge on seed bank function is fundamental for understanding the species regeneration patterns. This investigation was carried out to compare the ability of Eremanthus elaeagnus (Mart. ex DC.) Schultz-Bip, E. glomerulatus Less., and E. incanus (Less.) Less. to form a soil seed bank. Seeds (aquenes) of each of these three species were collected, stored in the laboratory and subsequently buried in the same area where they were collected, inside nylon bags. The bags were collected monthly or bimonthly for germination tests under continuous light and also in darkness at 20 °C (E. elaeagnus e E. glomerulatus) and at 25 °C (E. incanus). After 12 months, a further series of tests compared the germination of achenes that had been buried in soil and compared with those stored in the laboratory at 15, 20, 25, 30, 35, and 40 °C. After three months of burial, the seeds of E. elaeagnus and E. glomerulatus failed to germinate, whereas the seeds of E. incanus, even after burial for 18 months, retained germination percentage of between 1% and 30%. After one year stored in laboratory, the seeds of E. glomerulatus were no longer viable and seeds of E. elaeagnus e E. incanus had a germination percentage below that of newly collected seeds. The results showed that E. elaeagnus and E. glomerulatus do not form seed banks while E. incanus may form a small and persistent soil seed bank.

Low-dose doxycycline prevents inflammatory bone resorption in rats

Matrix metalloproteinases (MMP) are considered to be key initiators of collagen degradation, thus contributing to bone resorption in inflammatory diseases. We determined whether subantimicrobial doses of doxycycline (DX) (<=10 mg kg-1 day-1), a known MMP inhibitor, could inhibit bone resorption in an experimental periodontitis model. Thirty male Wistar rats (180-200 g) were subjected to placement of a nylon thread ligature around the maxillary molars and sacrificed after 7 days. Alveolar bone loss (ABL) was measured macroscopically in one hemiarcade and the contralateral hemiarcade was processed for histopathologic analysis. Groups of six animals each were treated with DX (2.5, 5 or 10 mg kg-1 day-1, sc, 7 days) and compared to nontreated (NT) rats. NT rats displayed significant ABL, severe mononuclear cell influx and increase in osteoclast numbers, which were significantly reduced by 5 or 10 mg kg-1 day-1 DX. These data show that DX inhibits inflammatory bone resorption in a manner that is independent of its antimicrobial properties.

Validation of a simple and inexpensive method for the quantitation of infarct in the rat brain

A gravimetric method was evaluated as a simple, sensitive, reproducible, low-cost alternative to quantify the extent of brain infarct after occlusion of the medial cerebral artery in rats. In ether-anesthetized rats, the left medial cerebral artery was occluded for 1, 1.5 or 2 h by inserting a 4-0 nylon monofilament suture into the internal carotid artery. Twenty-four hours later, the brains were processed for histochemical triphenyltetrazolium chloride (TTC) staining and quantitation of the schemic infarct. In each TTC-stained brain section, the ischemic tissue was dissected with a scalpel and fixed in 10% formalin at 0ºC until its total mass could be estimated. The mass (mg) of the ischemic tissue was weighed on an analytical balance and compared to its volume (mm³), estimated either by plethysmometry using platinum electrodes or by computer-assisted image analysis. Infarct size as measured by the weighing method (mg), and reported as a percent (%) of the affected (left) hemisphere, correlated closely with volume (mm³, also reported as %) estimated by computerized image analysis (r = 0.88; P < 0.001; N = 10) or by plethysmography (r = 0.97-0.98; P < 0.0001; N = 41). This degree of correlation was maintained between different experimenters. The method was also sensitive for detecting the effect of different ischemia durations on infarct size (P < 0.005; N = 23), and the effect of drug treatments in reducing the extent of brain damage (P < 0.005; N = 24). The data suggest that, in addition to being simple and low cost, the weighing method is a reliable alternative for quantifying brain infarct in animal models of stroke.

Folhas de alface lisa (Lactuca sativa) minimamente processadas armazenadas em atmosfera modificada: análises físicas, químicas e físico-químicas

Alfaces (Lactuca sativa) cv. lisa, após seleção e pré-lavagem, foram lavadas com água clorada a 5ºC contendo 150ppm de cloro residual livre e pH ajustado para 6.0, enxagüadas e centrifugadas por 8 minutos a 2200rpm. Em seguida, foram acondicionadas em embalagens plásticas de nylon poli 5 camadas, sem e com atmosfera modificada (N2 contendo 20ppm de O2 e no máximo 20ppm umidade) e estocadas a 4ºC. Durante 5 dias foram realizadas mensurações de pH, concentração de sólidos solúveis (graus Brix) e análises de acidez (mL NaOH 0,1M/100g folhas de alface). Os produtos sofreram acidificação detectável pela diminuição do pH em ambas as atmosferas. O incremento da acidez foi mostrado, sendo os registros maiores para as amostras controle (sem atmosfera modificada), e não ocorreram variações de graus Brix. Os resultados fizeram concluir que avanços tecnológicos vêm sendo alcançados visando melhorar a qualidade e vida-de-prateleira do vegetal.

Uso da acidez titulável no controle de qualidade do leite humano ordenhado

O perfil físico-químico do leite humano ordenhado cru (LHOc) com acidez titulável acima de 7ºD após 15 dias de congelamento, teores de creme, gordura total e valor energético, foram avaliados. Na etapa controle, os valores absolutos de creme, gordura total e valor energético (n=3887) foram determinados pelo método do crematócrito e a acidez titulável (n=4204) do LHOc por um método titulimétrico adaptado de leite de vaca. Na etapa teste, determinou-se o teor de creme, gordura total e valor energético de amostras (n=66) com acidez acima de 7ºD armazenadas entre -10º e -18ºC por 15 dias. A acidez titulável variou de 0,5 a 21ºD (3,52 ± 2,45ºD) e os teores de creme, gordura total e valor energético foram, respectivamente, 4,90 ± 0,25 %, 4,49 ± 0,26 % e 617,47 ± 17,37 Kcal/Litro. Houve redução significante nos teores de creme (6,45 ± 2,28% para 5,79 ± 2,57%), gordura total (4,0 ± 1,81% para 3,49 ± 1,76%) e valor energético (716,27 ± 176,59 Kcal/Litro para 666,82 ± 171,90 Kcal/Litro), com p<0,05. O uso do teste da acidez titulável constitui uma ferramenta importante no controle de qualidade do LHOc.

Efeito da polinização sobre a produção e qualidade de sementes de Adesmia latifolia

Com o objetivo de estudar o efeito da ação polinizadora da abelha doméstica (Apis mellifera L.) e seu desempenho na produção e qualidade das sementes de Adesmia latifolia (Spreng.) Vog. foi instalado um experimento na Estação Experimental Agronômica da UFRGS, em Eldorado do Sul, nos anos de 2000, 2001 e 2002. Após o início do florescimento, estabeleceram-se três tratamentos: presença somente da abelha doméstica (a); exclusão de abelhas e outros insetos (b), ambos por meio de gaiolas de tela de nylon, e área de livre acesso para abelhas e outros insetos (c). A produção média de sementes nos três anos foi de 5,4 e 83,5 kg/ha nos tratamentos a e c, respectivamente. No tratamento b não ocorreu a formação de lomentos e sementes e o número de flores não polinizadas foi elevado, evidenciando a necessidade de insetos polinizadores nesta cultura. Concluiu-se que a abelha doméstica não é eficiente na polinização de A. latifolia, pois coleta o néctar entre o cálice e a corola, não expondo os órgãos reprodutivos da flor. Esta espécie é dependente de abelhas silvestres, como Megachille sp. e Centris sp. para uma adequada polinização.

Lolium Multiflorum seeds in the soil: II. Longevity under natural conditions

The interest was the seed longevity dynamics of annual ryegrass in natural conditions as an important tool to explain its dynamics in no tillage systems used in the South of Brazil. The species is commonly managed for natural re-sowing and, in this way, allows cattle grazing with reduced costs during the winter time. In February of 2003, twenty bags of nylon screen containing sterilised soil with 100 seeds in each were randomly buried in the field, 5 cm deep. Around every three or four months, four sacks were exhumed. Seeds were counted and tested using germination and tetrazolium tests.The seeds showed high primary dormancy, which was overcome very fast. After 108, 226, 326, 565 and 732 days of burial there were no significant differences as the secondary dormancy of the seeds that did not germinate in autumn was not high. The last exhumation period was significantly different from the others due to the strong decay on seed viability. As few seeds remained viable after 732 days, the soil seed bank was classified as transient, being evident that in annual pastures the transitory seed banks have a main role in the regeneration of the species.

Tamanho de frutos e de sementes e sua influência na germinação de jatobá-do-cerrado (Hymenaea stigonocarpa var. stigonocarpa Mart. ex Hayne, Leguminosae - Caesalpinoideae)

Neste estudo foi descrito a biometria de frutos e de sementes de uma população de Hymenaea stigonocarpa var. stigonocarpa foi avaliado o efeito da massa de sementes na proporção e no tempo de germinação, sob condições de laboratório (câmara de germinação) e em viveiro, considerando como critérios de germinação a protrusão da raiz primária e a expansão de eófilos. Esta população de jatobá-do-cerrado apresentou uma grande variação no tamanho de frutos e de sementes. A massa das sementes variou entre 0,546 e 7,666 g e estas foram classificadas em pequenas, médias e grandes. Uma proporção maior de sementes classificadas como médias, emitiu a raiz primária em relação às grandes, enquanto as pequenas ocuparam posição intermediária. A massa de sementes não influencia a proporção de sementes que apresenta expansão de eófilos. As sementes grandes emitem a raiz primária mais rapidamente que as pequenas. O tempo médio da expansão de eófilos decresce com a redução da massa de sementes. Apesar das sementes médias e pequenas possuírem maior potencial para expor a raiz primária, estas apresentam maior taxa de mortalidade na transição entre as fases de protrusão da raiz primária e de expansão de eófilos.

”Kaikkialla tarvitaan humanisteja, kunhan vain oikea näkökulma löytyy!” Tutkielma Specia ry:n humanistijäsenten työhön sijoittumisesta ja työelämävahvuuksista

Humanistien työllistymistä on tutkittu aiemmin muun muassa erilaisten yliopiston seurantatutkimusten muodossa. Tämä käsillä oleva tutkielma on toteutettu tilaustyönä ammattiliitto Specia ry:lle. Tutkielmassa tarkastellaan Specia ry:n humanistisilta aloilta valmistuneiden FM-jäsenien työhönsijoittumista, jonka lisäksi kartoitetaan heidän käsityksiään tulevaisuudessa tarvittavista työelämävahvuuksista sekä FM-tutkinnon mukanaan tuomista työelämävahvuuksista. Aineisto kerättiin helmikuussa 2016 sähköisellä Webropol kyselylomakkeella, johon vastasi yhteensä 666 Specia ry:n FM jäsentä. Koska tutkimuksen kohderyhmänä olivat generalisti-humanistit, rajattiin analyysin ulkopuolelle opettajien pedagogiset suorittaneet, luonnontieteitä pääaineinaan lukeneet sekä tohtorin tai lisensiaatin tutkinnon suorittaneet vastaajat. Rajausten jälkeen tarkasteluun jäi 507 vastaajaa, joka oli 22 prosenttia mahdollisesta vastaajajoukosta. Aineistoa analysoitiin sekä kvantitatiivisesti että laadullisella sisällönanalyysilla. Tulokset teemoiteltiin ja luokiteltiin aineistosta löytyneiden yhdenmukaisuuksien perusteella ja niitä peilattiin yleisiin työelämätaitoihin sekä 2000-luvun taitoihin. Pääosin naisista koostunut vastaajajoukko oli keskittynyt pääkaupunkiseudulle ja suuriin kaupunkeihin. He olivat työllistyneet melko hyvin, useimmiten ylemmiksi toimihenkilöiksi yksityiselle sektorille. Tärkeimmät tulevaisuuden työelämävahvuuksina nähtiin joustavuus, halu ja kyky jatkuvaan oppimiseen sekä vuorovaikutustaidot. Tutkinnon tarjoamista vahvuuksista tärkeimmät olivat kyky kriittiseen ja laaja-alaiseen ajatteluun sekä kokonaisuuksien hallintaan, kieli-, viestintä- ja vuorovaikutustaidot sekä kulttuurientuntemus. Humanistien laaja-alaisuutta ja moninaisuusosaamista tulisi hyödyntää uskaliaammin työelämässä ja humanistien tulisi myös itse oppia arvostamaan omaa monipuolisuuttaan.