bluuebunny/crossref_metadata_2025 huggingface dataset:
Criação e observações preliminares da biologia de Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) em feijão-de-porco Canavalia ensiformis (L.)
Authors: Lopes Rogério B. , Alves Sérgio B.
Published: April 2006

A dificuldade de coleta de insetos no campo torna a criação de tripes em laboratório fundamental para o desenvolvimento de pesquisas. O objetivo do presente estudo foi desenvolver um sistema de criação de Frankliniella occidentalis (Pergande) em condições de laboratório, para o fornecimento de um grande número de insetos para pesquisas em biologia e controle da espécie. A colônia foi obtida pela multiplicação do tripes em um recipiente de acrílico sobre plantas de feijão-de-porco Canavalia ensiformis (L.), com fornecimento de pólen para alimentação suplementar de adultos. A temperatura e a umidade dentro do recipiente de criação foram mantidas entre 25 a 28(0)C e 80 a 95%, respectivamente. O tempo de desenvolvimento médio da espécie para casais individualizados foi em torno de nove dias, considerando o período da eclosão das primeiras ninfas até a emergência dos primeiros adultos; o número de descendentes produzidos por fêmea foi de 14,3 ninfas. A longevidade de fêmeas foi, em média, 8,3 dias, e as viabilidades dos estágios de ninfas e pupas foram em torno de 83 e 90%, respectivamente. Estimou-se a produção de 22,5 ninfas/fêmea em criação múltipla de casais, após um período de acasalamento e oviposição de 96 horas. No sistema de criação desenvolvido foram obtidas entre 50 e 150 ninfas de segundo ínstar por folha, sete dias após a introdução da planta no recipiente. Este sistema mostrou-se adequado, fornecendo de forma prática um grande número de insetos para experimentos de biologia e controle da praga.
Efeito do tratamento hidrotérmico de mangas na mortalidade de larvas de Ceratitis capitata (Wied.) (Diptera: Tephritidae)
Authors: Mendonça Marcelo da C. , Nascimento Antonio S. , Caldas Ranulfo C. , Pereira Filho Carlos A.
Published: April 2006

Mangas das cultivares `Keitt', `Tommy Atkins' e `Haden', infestadas por larvas de mosca do mediterrâneo, Ceratitis capitata (Wied.), foram submetidas ao tratamento hidrotérmico a 46,1ºC. Os frutos foram divididos em duas faixas de peso, de 450 a 650g e de 651 a 800g, tratados por um período de 75 e 90 minutos, respectivamente. Do total dos frutos infestados e imersos em água quente, 75% foram avaliados visando quantificar o total de larvas mortas, os 25% restantes foram mantidos como controle. Nos frutos infestados por larvas de 1º e 2º estádio, a mortalidade foi de 100%. Nos testes com larvas de 3º estádio houve sobrevivência de quatro e três adultos em frutos com pesos acima de 540g e de 730 g nos tempos de imersão de 75 e 90 minutos, respectivamente.
Estágios ninfais fotossensíveis à indução da diapausa em Euschistus heros (Fabr.) (Hemiptera: Pentatomidae)
Authors: Mourão Ana P. M. , Panizzi Antônio R.
Published: April 2006

Foram desenvolvidos estudos em laboratório com o percevejo-marrom Euschistus heros (Fabr.) para se determinar o estágio fotossensível à indução da diapausa. Utilizaram-se duas combinações de fotoperíodo 10L: 14E e 14L: 10E mantendo-se constante a temperatura em 25 ± 1ºC e a umidade relativa em 65 ± 5%. Fases distintas do desenvolvimento dos insetos foram submetidas às combinações fotoperiódicas, com os seguintes tratamentos: T1 = 10L: 14E (ovo-adulto); T2 = 14L: 10E (ovo) e 10L: 14E (1º ínstar-adulto); T3 = 14L: 10E (ovo-1º ínstar) e 10L: 14E (2º ínstar-adulto); T4 = 14L: 10E (ovo-2º ínstar) e 10L: 14E (3º ínstar-adulto); T5 = 14L: 10E (ovo-3º ínstar) e 10L: 14E (4º ínstar-adulto); e T6 = 14L: 10E (ovo-4º ínstar) e 10L: 14E (5º ínstar-adulto). Sob fotoperíodo de dias curtos, de ovo a adulto (T1), o tempo de incubação dos ovos foi maior (6,1 dias) do que o observado nos demais tratamentos (5,3 a 5,6 dias). O tempo total de desenvolvimento foi maior (35,5 dias) para insetos submetidos a fotoperíodo de dias curtos, a partir do ovo (T1), do 1º ínstar (T2), do 2º ínstar (T3) ou do 4º ínstar (T4), do que para os insetos sob fotoperíodo de dias curtos a partir do 4º (T5) ou 5º ínstar (T6; cerca de 32,0 dias). A mortalidade total foi maior (56,7%) para os insetos que permaneceram sob fotoperíodo de dias curtos, de ovo a adulto (T1), do que para aqueles nos demais tratamentos (26,7 a 45,0%). Insetos submetidos ao fotoperíodo de dias curtos, a partir do ovo (T1), 1º ínstar (T2), 2º ínstar (T3) ou 3º ínstar (T4) apresentaram de 84,8% a 100% dos indivíduos em diapausa. A partir do tratamento com fotoperíodo longo, até o 3º ínstar (T5), não ocorreu mais diapausa. Esses resultados demonstram que a fotossensibilidade de E. heros inicia-se nos primeiros estágios de desenvolvimento, e que se acentua a partir do 3º ínstar.
Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae): técnica de criação e biologia em diferentes temperaturas
Authors: Chagas Marcone C.M. , Parra José R.P.
Published: April 2006

Desenvolveu-se uma técnica de criação do minador-dos-citros, Phyllocnistis citrella Stainton, bem como avaliou-se o efeito de sete temperaturas (18, 20, 22, 25, 28, 30 e 32 ± 1°C), nas condições de 60 ± 10% UR e fotofase de 14 h, sobre as fases imaturas da praga, a fim de se obterem subsídios para a criação desse inseto e de seus inimigos naturais de forma contínua em laboratório. A metodologia desenvolvida, utilizando-se plantas de limão-cravo (Citrus limonia, L. Osbeck) cultivadas em tubetes como hospedeiro de P. citrella, mostrou-se adequada à criação contínua do inseto em laboratório. Pode também ser adaptada para produção de inimigos naturais, uma vez que é possível sincronizar as produções da praga (hospedeiro) e dos inimigos naturais, lançando-se mão das variações de desenvolvimento da praga em função das temperaturas estudadas. As condições térmicas adequadas ao desenvolvimento de P. citrella variaram com o seu estágio, sendo a temperatura de 30ºC favorável ao desenvolvimento embrionário, e a de 32ºC, a mais adequada para as fases larval e pupal.
Componentes químicos associados à resistência de Lycopersicon hirsutum f. typicum a Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)
Authors: Ecole Carvalho C. , Picanço Marcelo , Moreira Márcio D. , Magalhães Sérgio T.V.
Published: April 2006

Este trabalho foi conduzido em casa de vegetação no Campus da Universidade Federal de Viçosa, Minas Gerais, Brasil de maio a setembro de 1997 e objetivou estudar a resistência do acesso LA 1777 de Lycopersicon hirsutum f. typicum a Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) e os prováveis compostos químicos envolvidos na resistência. Utilizaram-se as cultivares de Santa Clara (tomate para consumo in natura) e IPA-5 (tomate industrial) de Lycopersicon esculentum como padrões de suscetibilidade à praga. Avaliaram-se os números de minas pequenas (comprimento < 0,5 cm) e grandes (comprimento > 0,5 cm); sobrevivência, estádio de desenvolvimento do inseto, peso de pupas, proporção sexual, fertilidade de adultos e a taxa de eclosão de larvas. Foram identificados picos nas correntes de íons do extrato hexânico das folhas e as prováveis substâncias associadas a estes utilizando-se cromatógrafo a gás acoplado a espectrômetro de massa. L. hirsutum f. typicum apresentou resistência à traça do tomateiro em relação a L. esculentum, o que refletiu em menor número de minas grandes/folha e maiores duração da fase larval, mortalidade de larvas e número de minas pequenas de T. absoluta. Foram identificados 14 picos nas correntes de íons, com tempos de 10,43 (pico 1) a 26,03 min. (pico 14). Os picos 8, 9, 10 e 12 estiveram relacionados com a resistência de L. hirsutum f. typicum a T. absoluta. O pico 14 ocorreu apenas na cultivar Santa Clara e esteve associado ao aumento da suscetibilidade do tomateiro a T. absoluta. Os prováveis compostos associados ao pico oito foram os sesquiterpenos 2,5,5-trimetil-1,3,6-heptatrieno, (+) canfeno, farneseno ou santalol. As prováveis substâncias associadas ao pico nove foram os sesquiterpenos α-bergamoteno, farneseno, β-sinesal e farnesol. Nγo foram encontradas substâncias prováveis associadas aos picos 10, 12 e 14.
Impact of biocatalyst and moisture content on toluene/xylene mixture biofiltration
Authors: Klapková Eva , Halecký Martin , Fitch Mark , Soccol Carlos Ricardo , Paca Jan
Published: April 2006

The objective of this work was to determine the influence of microbial inoculation on degradation efficiency. Three biofilters were used for the treatment of waste gas. A mixture of compost and perlite (8:2) served as the packing material. One biofilter was inoculated with a constructed microbial population. The second remained uninoculated, having the natural population present in the compost. The third biofilter was uninoculated and the packing material was sterilized. The degradation ability of the uninoculated biofilter started to drop after 18 days, while the removal efficiency of inoculated biofilter was stable. The sterile biofilter proved to have no removal efficiency. Moisture content of the packing and ability of the packing to keep moisture was tested. The results showed a significant dependence of the degradation efficiency on the packing moisture content, with highest removal efficiency observed at 70 % moisture content.
Propylthiouracil-induced hypothyroidism protects ionizing radiation-induced multiple organ damage in rats
Authors: Şener G , Kabasakal L , Atasoy B M , Erzik C , Velioğlu-Öğünç A , Çetinel Ş , Contuk G , Gedik N , Yeğen B Ç
Published: April 2006

The objective of this study was to examine the potential radioprotective properties of propylthiouracil (PTU)-induced hypothyroidism against oxidative organ damage induced by irradiation. Sprague–Dawley rats were pre-treated with saline or PTU (10 mg/kg i.p.) for 15 days, and were then exposed to whole-body irradiation (800 cGy). A group of rats were decapitated at 6 h after exposure to irradiation, while another group was followed for 72 h after irradiation, during which saline or PTU injections were repeated once daily. Lung, liver, kidney and ileum samples were obtained for the determination of malondialdehyde (MDA; an index of lipid peroxidation) and glutathione (GSH, an antioxidant) levels, myeloperoxidase activity (MPO; an index of tissue neutrophil accumulation) and collagen contents, while oxidant-induced DNA fragmentation was evaluated in the ileal tissues. All tissues were also examined microscopically and assayed for the production of reactive oxidants using chemiluminescence (CL). Lactate dehydrogenase (LDH), an indicator of tissue damage, and tumour necrosis factor-α (TNFα) were assayed in serum samples. Irradiation caused a significant decrease in GSH level, which was accompanied by significant increases in MDA levels, MPO activity, CL levels and collagen content of the tissues studied (P<0.05–0.001). Similarly, serum TNFα and LDH were elevated in the irradiated rats as compared with the control group. On the other hand, PTU treatment reversed all these biochemical indices, as well as histopathological alterations induced by irradiation. Our results suggested that PTU-induced hypothyroidism reduces oxidative damage in the lung, hepatic, renal and ileal tissues probably due to hypometabolism, which is associated with decreased production of reactive oxygen metabolites and enhancement of antioxidant mechanisms.
Intra-adrenal mechanisms in the response to chronic stress: investigation in a rat model of emotionality
Authors: Kosti O , Raven P W , Renshaw D , Hinson J P
Published: April 2006

The exploratory behaviour of the genetically derived Maudsley rat model of emotionality has been well characterized. Maudsley reactives (MR) present with more ‘anxious-like’ behaviour than Maudsley nonreactives (MNR). Although this behaviour is assumed to be associated with altered adrenocortical function, the few studies addressing this issue have produced inconsistent findings. We therefore set out to investigate the adrenal endocrinology of the MR and MNR strains. Control Wistars, the ancestors of the Maudsleys, have been used for the first time to set the baseline for all the experiments carried out. It was found that the MNR strain had a significantly blunted adrenocorticotrophic hormone (ACTH) response to restraint stress compared with Wistars, but a normal corticosterone response. Conversely, the MR had a significantly exaggerated ACTH response to restraint stress, but a normal corticosterone response. This finding suggested that the MR adrenal is less sensitive to ACTH than the MNR. This was confirmed by investigating the corticosterone dose–response to ACTH in adrenals from the two strains incubated in vitro. Several possible intra-adrenal regulators were investigated, but the only significant molecular difference in the adrenal glands from the two strains was the level of expression of neuropeptide Y (NPY), which is known to be a stress-responsive peptide in the adrenal. We propose that intra-adrenal NPY is responsible for blunting adrenocortical responses to ACTH stimulation in the MR strain. The observed changes in adrenal NPY suggest that this rat strain may serve as a model of chronic stress, with the MR phenotype representing maladaptation.
The present and future of electronic paper
Authors: Henzen Alex , van de Kamer Jan
Published: April 2006

Abstract— With the rise of electrophoretic‐display media from several sources, the world is opening up for new uses of electronic displays. Where “immersive reading” used to be a task strictly reserved for paper, displays can now fulfill that role. Many challenges still remain, such as full‐color photograph‐like performance and video speeds. However, in view of recent accomplishments showing near‐video‐speed switching and potential for full color, after electrophoretic displays obtain a slice of the reading market, application of these developments will take us a significant step towards full‐color animated paper‐like displays. The developments that have led to the presence of electronic paper in the market today will be described, and developments that are about to happen will be discussed.
Protective layer for high‐efficiency PDPs driven at low voltage
Authors: Motoyama Yasushi , Kurauchi Toshiharu
Published: April 2006

Abstract— The sustain pulse voltage of a panel for 66‐kPa Ne + Xe (5–30%) with an (SrCa)O protective layer is 20–40% lower than that with an MgO protective layer. The luminous efficiency of the panel with a Ne + Xe (30%) (SrCa)O protective layer is 1.5 times that of the conventional panel with a Ne + Xe (10%) MgO protective layer; the sustain pulse voltages of these panels are almost the same. The power loss caused by panel capacitance is proportional to the second power of the sustain pulse voltage. Using the (SrCa)O protective layer for Xe (5–30%), the power loss is reduced by 35–60% compared with the MgO protective layer. It follows that, using the (SrCa)O protective layer, we can increase the Xe content with little power loss and thus achieve high‐efficiency PDPs. As for MgO and CaO with Xe ions, electrons are probably ejected from only the defect states. On the other hand, as for the SrO with Xe ions, it is likely that electrons can be ejected from not only defect states but also the valance band. This seems to be the reason why the driving voltage is lower with the (SrCa)O protective layer than with the MgO protective layer.
Accurate determination of pretilt angle in twisted‐nematic liquid‐crystal cells by using a rotating analyzer
Authors: Kitamura Michio , Kobayashi Shunsuke , Mori Katsumi
Published: April 2006

Abstract— A new optical method for determining the pretilt angle ψ0, particularly on twisted‐nematic (TN) liquid‐crystal (LC) cells, is proposed. ψ0 was rapidly determined with good reproducibility on a TN‐LC cell by using a rotating analyzer optical system, a twist angle Φ, the azimuth of the director at a substrate, ϕ0, and the retardation Δnd as known values. The thickness d was also determined simultaneously with ψ0. ψ0 and d were determined within minutes. ψ0 was previously determined to be in the range of 0.1° with a standard deviation of 0.01°; this was obtained by repeating the measurement 50 times. The principle behind the determination and the experimental set up are described in detail.
Neutralization Potential Determination of Siderite (FeCO3) Using Selected Oxidants
Authors: Haney E. B. , Haney R. L. , Hossner L. R. , White G. N.
Published: April 2006

Siderite (FeCO3) is commonly found in coal overburden and, when present, can cause interference in the determination of neutralization potential (NP). Under acidic testing conditions, FeCO3 reacts to neutralize acid, which contributes to the NP. However, continued weathering of FeCO3 (oxidation of Fe2+ and hydrolysis of Fe3+) produces a neutral to slightly acidic solution. The effects of hydrogen peroxide (H2O2), potassium permanganate (KMnO4), and O2 on the laboratory measurement of NP of siderite samples taken from overburden were examined. All oxidation treatments lowered the NP values of the siderite samples as compared with the standard USEPA method. However, oxidation with H2O2 produced variable results depending on the amount of H2O2 added. Neutralization potential values obtained after oxidation treatments were highly correlated with Mn concentration. Reaction products (i.e., 2‐line ferrihydrite) of siderite samples with H2O2 and KMnO4 were not representative of natural siderite weathering. Oxidation with O2 produced the lowest NP values for siderite samples. The reaction products produced by oxidation with O2 most closely represent those intermediate products formed when siderite is exposed to atmospheric weathering conditions. Oxidation with O2 also proved to be the most reproducible method for accurately assessing NP when siderite is present in overburden samples.
Aerating Grassland before Manure Application Reduces Runoff Nutrient Loads in a High Rainfall Environment
Authors: van Vliet L. J. P. , Bittman S. , Derksen G. , Kowalenko C. G.
Published: April 2006

The effect of mechanically aerating grassland before liquid manure application in the fall on surface runoff and transport of nutrients and solids was studied in a high rainfall area. The two treatments were control and aeration, the latter receiving one pass with an aerator perpendicular to the slope before fall application of liquid manure (dairy in Years 1–3 and swine in Year 4). Treatments were randomly assigned on 3 to 5% sloping land with a silt loam surface soil (Aquic Dystroxerept) planted in orchardgrass (Dactylis glomerata L.). Runoff from natural rainfall events was sampled for nutrient and solids analysis. Aeration significantly reduced runoff and loads of suspended solids, total Kjeldahl N (TKN), and dissolved reactive P in all years. Annual runoff amounts were reduced by 47 to 81%, suspended and volatile solid loads by 48 to 69% and 42 to 83%, respectively, TKN loads by 56 to 81%, and total P (TP) loads by 25 to 75%. Loads of the soluble nutrient NH4–N, dissolved reactive P, and K were reduced by 41 to 83%. The first three runoff events after manure application accounted for approximately one‐third of the annual total runoff and solid and nutrient loads when averaged across treatments, with loads of TKN, K, and NH4–N totaling 4.4, 3.3, and 1.9 kg ha−1, respectively. Aeration slightly increased downward movement of NO3–N, but not other nutrients in the soil. Thus mechanical aeration can be an effective tool for reducing runoff and loads of solids and nutrients after surface application of liquid manure on sloping grassland.
Reducing Phosphorus Runoff from Dairy Farms
Authors: Bosch Darrell J. , Wolfe Mary Leigh , Knowlton Katharine F.
Published: April 2006

Phosphorus (P) runoff from manure can lead to eutrophication of surface water and algae growth. This study evaluates the impacts of alternative P reduction practices on dairy farm net returns and on potential P runoff. The P control practices include dairy herd nutrient management, crop nutrient management, and runoff and erosion control. Four farms representative of dairies in the Virginia Shenandoah Valley are simulated including dairies with and without supplementary broiler enterprises and with average and below average land area. A mathematical programming model was developed to predict farm production and net returns and the GLEAMS model was used to predict potential P runoff. The farms are evaluated under four scenarios: Scenario 1, no constraint on P runoff with access to crop nutrient, runoff and erosion control strategies but no access to dairy herd nutrient control strategies; Scenario 2, no constraint on P runoff with access to all crop and dairy herd nutrient control strategies; Scenario 3, constraint on P runoff with access to crop nutrient, runoff and erosion control strategies but no access to dairy herd nutrient control strategies; and Scenario 4, constraint on P runoff with access to all crop and dairy herd nutrient control strategies. Under Scenario 2, the herd nutrient control strategies increase milk output per cow and net returns on both farms and reduce P content of manure and P runoff. Under Scenario 3, limiting P runoff reduces farm returns by 1 and 3% on the average and small farms, respectively. Under Scenario 4, the P runoff constraint is less costly, reducing returns by less than 1% on both farms. Animal nutrient control strategies should be an important part of pollution control policies and programs for livestock intensive watersheds.
Transport of a Mixture of Chlorinated Solvent Vapors in the Vadose Zone of a Sandy Aquifer: Experimental Study and Numerical Modeling
Authors: Bohy Martine , Dridi Lotfi , Schäfer Gerhard , Razakarisoa Olivier
Published: April 2006

Experimental and modeling studies were performed to investigate the simultaneous transport of trichloroethylene (TCE) and perchloroethylene (PCE) in the vadose zone of a large (25 by 12 by 3 m) well‐instrumented artificial aquifer called SCERES. The experimental facility, made up of a 1‐m‐thick saturated zone and a 2‐m‐thick unsaturated zone, allowed direct measurements of the contaminants in both the liquid and gas phases. Main objectives of the study were to obtain a better understanding of the fate and transport of chlorinated solvents in the subsurface and, more specifically, to compare simultaneously measured TCE and PCE volatilization rates from the soil surface with predictions obtained with both a comprehensive multiphase multicomponent numerical model (SIMUSCOPP) and a quasianalytical approach based on Fick's first law. The numerical and quasianalytical results generally agreed very well with the observed data. Transient PCE and TCE vapor phase concentrations calculated with the numerical model were found to be close to the observations, which indicated applicability of Raoult's Law. A comparison of observed and calculated TCE and PCE concentrations in the capillary fringe showed more impact of water infiltration on the simulations as compared with the observed data, which may reflect a lack of equilibrium between the gaseous and aqueous phase during leaching for the given experimental flow conditions. A sensitivity analysis showed that the adopted source boundary condition (a fixed nonaqueous phase liquid [NAPL] saturation distribution instead of an injected DNAPL source) did not have much influence on the concentration breakthrough curves, but that temperature can be an important factor influencing the results.
LIGHT (TNFSF14), a novel mediator of bone resorption, is elevated in rheumatoid arthritis
Authors: Edwards J. R. , Sun S. G. , Locklin R. , Shipman C. M. , Adamopoulos I. E. , Athanasou N. A. , Sabokbar A.
Published: April 2006

Objective

Human osteoclast formation from mononuclear phagocyte precursors involves interactions between tumor necrosis factor (TNF) ligand superfamily members and their receptors. LIGHT is a transmembrane protein expressed and shed from the surface of activated T cells. Since activated T cells have been implicated in osteoclastogenesis in rheumatoid arthritis (RA), this study sought to determine whether LIGHT can regulate RANKL/cytokine‐induced osteoclast formation, to identify the mechanism by which LIGHT influences osteoclastogenesis, and to investigate the presence of LIGHT in the serum of RA patients.

Methods

The effect of LIGHT on human and murine osteoclast formation was assessed in the presence and absence of neutralizing reagents to known osteoclastogenic factors. Serum levels of LIGHT in RA patients were measured by enzyme‐linked immunosorbent assay.

Results

In the presence and absence of RANKL, LIGHT induced osteoclast formation from both human peripheral blood mononuclear cells and murine macrophage precursors, in a dose‐dependent manner, whereas no inhibition was observed by adding osteoprotegerin, RANK:Fc, TNFα, or interleukin‐8 or by blocking the LIGHT receptors herpesvirus entry mediator or lymphotoxin β receptor. However, formation of osteoclasts was significantly decreased by the soluble decoy receptor for LIGHT, DcR3, and by blocking antibodies to the p75 component of the TNF receptor. A significant increase in LIGHT levels in the serum of RA patients compared with normal controls was also noted.

Conclusion

Our results indicate that LIGHT promotes RANKL‐mediated osteoclastogenesis and that it can induce osteoclast formation by a mechanism independent of RANKL. The increased concentration of LIGHT in patients with RA raises the possibility that LIGHT may play a role in immunopathogenic conditions that are associated with localized or systemic bone loss.
Evaluation of the alkaline Comet assay conducted with the wetlands plant Bacopa monnieri L. as a model for ecogenotoxicity assessment
Authors: Vajpayee Poornima , Dhawan Alok , Shanker Rishi
Published: April 2006

Wetlands play a key role in maintaining environmental quality, and wetlands plants could serve as model organisms for determining the genotoxic effects of pollutants contaminating these areas. In the present study, DNA damage was evaluated in a wetlands plant, Bacopa monnieri L., as a potential tool for the assessment of ecogenotoxicity. The Comet assay was used for detecting DNA damage in B. monnieri exposed to two model mutagens, ethyl methanesulfonate (EMS) and methyl methanesulfonate (MMS). Significant (P < 0.05) dose‐dependent increases in DNA damage were observed following treatments conducted by exposing both isolated nuclei (acellular or in vitro exposure) and whole plants (in vivo exposure) to 0.01–5 mM EMS and 0.05–100 μM MMS for 2 hr at (26 ± 2)°C. The assay was then used to evaluate the genotoxic potential of cadmium (Cd), a wetlands contaminant. In vitro exposure of nuclei from untreated leaves to 0.001–200 μM Cd for 2 hr resulted in significant (P < 0.05) levels of DNA damage. Cd concentrations ≥0.01 μM induced DNA damage as evidenced by increases in the Olive tail moment. In vivo exposure of plants to 0.01–500 μM Cd for 2, 4, and 18 hr resulted in dose‐ and time‐dependent increases in DNA damage in the nuclei isolated from roots and leaves. Cd‐induced DNA damage was greater in roots than leaves. To our knowledge, this is the first report describing the use of a wetlands plant for genotoxicity assessment, using the Comet assay. Environ. Mol. Mutagen., 2006. © 2006 Wiley‐Liss, Inc.
Porous hybrid structures based on P(DLLA‐co‐TMC) and collagen for tissue engineering of small‐diameter blood vessels
Authors: Buttafoco Laura , Boks Niels P. , Engbers‐Buijtenhuijs Paula , Grijpma Dirk W. , Poot Andre A. , Dijkstra Piet J. , Vermes Istvan , Feijen Jan
Published: April 2006

Poly (D,L‐lactide)‐7co‐(1,3‐trimethylene carbonate) [P(DLLA‐co‐TMC)] (83 mol % DLLA) was used to produce matrices suitable for tissue engineering of small‐diameter blood vessels. The copolymer was processed into tubular structures with a porosity of ∼98% by melt spinning and fiber winding, thus obviating the need of organic solvents that may compromise subsequent cell culture. Unexpectedly, incubation in culture medium at 37°C resulted in disconnection of the contact points between the polymer fibers. To improve the structural stability of these P(DLLA‐co‐TMC) scaffolds, a collagen microsponge was formed inside the pores of the synthetic matrix by dip coating and freeze drying. Hybrid structures with a porosity of 97% and an average pore size of 102 μm were obtained. Structural stability was preserved during incubation in culture medium at 37°C. Smooth‐muscle cells (SMCs) were seeded in these hybrid scaffolds and cultured under pulsatile flow conditions in a bioreactor (120 beats/min, 80–120 mmHg). After 7 days of culture in a dynamic environment viable SMCs were homogeneously distributed throughout the constructs, which were five times stronger and stiffer than noncultured scaffolds. Values for yield stress (2.8 ± 0.6 MPa), stiffness (1.6 ± 0.4 MPa), and yield strain (120% ± 20%) were comparable to those of the human artery mesenterica. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Experimental Requirements for an Efficient Control of Free‐Radical Polymerizations via the Reversible Addition‐Fragmentation Chain Transfer (RAFT) Process
Authors: Favier Arnaud , Charreyre Marie‐Thérèse
Published: April 2006

Summary: Reversible addition‐fragmentation chain transfer (RAFT) polymerization is a recent and very versatile controlled radical polymerization technique that has enabled the synthesis of a wide range of macromolecules with well‐defined structures, compositions, and functionalities. The RAFT process is based on a reversible addition‐fragmentation reaction mediated by thiocarbonylthio compounds used as chain transfer agents (CTAs). A great variety of CTAs have been designed and synthesized so far with different kinds of substituents. In this review, all of the CTAs encountered in the literature from 1998 to date are reported and classified according to several criteria : i) the structure of their substituents, ii) the various monomers that they have been polymerized with, and iii) the type of polymerization that has been performed (solution, dispersed media, surface initiated, and copolymerization). Moreover, the influence of various parameters is discussed, especially the CTA structure relative to the monomer and the experimental conditions (temperature, pressure, initiation, CTA/initiator ratio, concentration), in order to optimise the kinetics and the efficiency of the molecular‐weight‐distribution control.

Schematic of the RAFT polymerization.

magnified image

Schematic of the RAFT polymerization.
Synthesis of poly(ethylene oxide) with pending 2,2,6,6‐tetramethylpiperidine‐1‐oxyl groups and its further initiation of the grafting polymerization of styrene
Authors: Jia Zhongfan , Fu Qiang , Huang Junlian
Published: April 2006

A new stratagem for the synthesis of amphiphilic graft copolymers of hydrophilic poly(ethylene oxide) as the main chain and hydrophobic polystyrene as the side chains is suggested. A poly(ethylene oxide) with pending 2,2,6,6‐tetramethylpiperidine‐1‐oxyls [poly(4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐co‐ethylene oxide)] was first prepared by the anionic ring‐opening copolymerization of ethylene oxide and 4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl, and then the graft copolymerization of styrene was completed with benzoyl peroxide as the initiator in the presence of poly(4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐co‐ethylene oxide). The polymerization of styrene was under control, and comblike, amphiphilic poly(ethylene oxide)‐g‐polystyrene was obtained. The copolymer and its intermediates were characterized with size exclusion chromatography, 1H NMR, and electron spin resonance in detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3836–3842, 2006
Room temperature electroluminescence from multilayer GeSi heterostructures
Authors: Tonkikh A. A. , Cirlin G. E. , Talalaev V. G. , Zakharov N. D. , Werner P.
Published: April 2006

Details of silicon diodes with Ge/Si multilayer quantum dot heterostructures embedded in the Si p–n junction grown by molecular beam epitaxy emitting in the range of 1.4–1.7 µm at room temperature and continuous injection pumping are discussed. Output power of the light emitting diode reaches 1 µW/cm2 at applied current density of 2 A/cm2. Photoluminescence and transmission electron microscopy show that the origin of intense luminescence is defect free stacked Ge quantum dot array formed inside the structure. It is shown that doping by antimony improves structure quality and increases photoluminescence efficiency at room temperature. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In‐situ monitoring of laser annealing by micro‐Raman spectroscopy for hydrogenated silicon nanoparticles produced in radio frequency glow discharge
Authors: Hill D. , Jawhari T. , Cespedes J. García , García J. Alvarez , Bertran E.
Published: April 2006

Low temperature Plasma Enhanced Chemical Vapour Deposition (PECVD) grown amorphous hydrogenated Si (a‐Si:H) thin films form the basis of many photovoltaic and microelectronic devices such as solar cells and TFTs. Amorphous hydrogenated silicon in the form of nanoparticles has been produced by power modulation of the PECVD processes. The stability of these nanoparticles under high temperatures and high power illumination is therefore of interest and to this end we report on combined laser annealing and in‐situ monitoring through the use of micro‐raman spectroscopy. Interpretation of spectra is done with the help of complementary techniques including scanning (SEM) and transmission electron microscopy (TEM). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integrating nanotubes into microsystems with electron beam lithography and in situ catalytically activated growth
Authors: Gjerde K. , Mora M. F. , Kjelstrup‐Hansen J. , Schurmann T. , Gammelgaard L. , Aono M. , Teo K. B. K , Milne W. I. , Bøggild P.
Published: April 2006

Integration of freestanding wire‐like structures such as multi walled carbon nanotubes (MWCNT) into microsystems has many potential applications. Devices such as AFM tips or improved electrodes for conductivity measurements are obvious candidates. Catalytically activated growth opens up the possibility of waferscale fabrication of such devices. We combine conventional microfabrication techniques with state of the art electron beam lithography (EBL) to precisely position catalyst nanoparticles with sub 100 nm diameter into the microsystems. In particular, we have explored two main approaches which allow the catalyst material deposition to occur after the microfabrication is finished, thus avoiding contamination of cleanroom equipment. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the weakly nonlinear development of Tollmien-Schlichting wavetrains in boundary layers
Authors: Wu Xuesong , Stewart Philip A. , Cowley Stephen J.
Published: April 2006

The nonlinear development of a weakly modulated Tollmien-Schlichting wavetrain in a boundary layer is studied theoretically using high-Reynolds-number asymptotic methods. The ‘carrier’ wave is taken to be two-dimensional, and the envelope is assumed to be a slowly varying function of time and of the streamwise and spanwise variables. Attention is focused on the scalings appropriate to the so-called ‘upper branch’ and ‘high-frequency lower branch’. The dominant nonlinear effects are found to arise in the critical layer and the surrounding ‘diffusion layer’: nonlinear interactions in these regions can influence the development of the wavetrain by producing a spanwise-dependent mean-flow distortion. The amplitude evolution is governed by an integro-partial-differential equation, whose nonlinear term is history-dependent and involves the highest derivative with respect to the spanwise variable. Numerical solutions show that a localized singularity can develop at a finite distance downstream. This singularity seems consistent with the experimentally observed focusing of vorticity at certain spanwise locations, although quantitative comparisons have not been attempted.
Solidification of pressure-driven flow in a finite rigid channel with application to volcanic eruptions
Authors: Lister John R. , Dellar Paul J.
Published: April 2006

Competition between conductive cooling and advective heating occurs whenever hot fluid invades a cold environment. Here the solidification of hot viscous flow driven by a fixed pressure drop through an initially planar or cylindrical channel embedded in a cold rigid solid is analysed. At early times, or far from the channel entrance, the flow starts to solidify and block the channel, thus reducing the flow rate. Close to the channel entrance, and at later times, the supply of new hot fluid starts to melt back the initial chill. Eventually, either solidification or meltback becomes dominant throughout the channel, and flow either ceases or continues until the source is exhausted. The evolution of the dimensionless system, which is characterized by the initial Péclet number Pe, the Stefan number S and the dimensionless solidification temperature Θ, is calculated numerically and by a variety of asymptotic schemes. The results show the importance of variations along the channel and caution against models based on a single ‘representative’ width. The critical Péclet number Pec, which marks the boundary between eventual solidification and eventual meltback, is determined for a wide range of parameters and found to be much larger for cylindrical channels than for planar channels, owing to the slower rate of decay of the heat flux into the solid in a cylindrical geometry. For a planar channel Pec is given by the simple algebraic result Pec ∼ 0.46[Θ2/(1 - Θ)(S + 2/π)]3 when (1 - Θ)−1 [Gt ] S [Gt ] 1, but in general it requires numerical solution. Similar analyses, in which there is a spatially varying and time-dependent interaction between the rates of solidification and flow, have a range of applications to geological and industrial processes.
The three-dimensional interaction of a streamwise vortex with a large-chord lifting surface: theory and experiment
Authors: Bodstein Gustavo C. R. , George Albert R. , Hui C.-Y.
Published: April 2006

The three-dimensional vortex flow that develops around a close-coupled canard-wing configuration is characterized by a strong interaction between the vortex generated at the canard and the aircraft wing. In this paper, a theoretical potential flow model is devised to uncover the basic structure of the pressure and velocity distributions on the wing surface. The wing is modelled as a semi-infinite lifting-surface set at zero angle of attack. It is assumed that the vortex is a straight vortex filament, with constant strength, and lying in the freestream direction. The vortex filament is considered to be orthogonal to the leading-edge, passing a certain height over the surface. An incompressible and steady potential flow formulation is created based on the three-dimensional Laplace's equation for the velocity potential. The boundary-value problem is solved analytically using Fourier transforms and the Wiener-Hopf technique. A closed-form solution for the velocity potential is determined, from which the velocity and pressure distributions on the surface and a vortex path correction are obtained. The model predicts an anti-symmetric pressure distribution along the span in region near the leading-edge, and a symmetric pressure distribution downstream from it. The theory also predicts no vertical displacement of the vortex, but a significant lateral displacement. A set of experiments is carried out to study the main features of the flow and to test the theoretical model above. The experimental results include helium-soap bubble and oil-surface flow pattern visualization, as well as pressure measurements. The comparison shows good agreement only for a weak interaction case, whereas for the case where the interaction is strong, secondary boundary-layer separation and vortex breakdown are observed to occur, mainly owing to the strong vortex-boundary layer interaction. In such a case the model does not agree well with the experiments.
Rapidly rotating turbulent Rayleigh-Bénard convection
Authors: Julien K. , Legg S. , Mcwilliams J. , Werne J.
Published: April 2006

Turbulent Boussinesq convection under the influence of rapid rotation (i.e. with comparable characteristic rotation and convection timescales) is studied. The transition to turbulence proceeds through a relatively simple bifurcation sequence, starting with unstable convection rolls at moderate Rayleigh (Ra) and Taylor numbers (Ta) and culminating in a state dominated by coherent plume structures at highRaandTa. Like non-rotating turbulent convection, the rapidly rotating state exhibits a simple power-law dependence onRafor all statistical properties of the flow. When the fluid layer is bounded by no-slip surfaces, the convective heat transport (Nu− 1, whereNuis the Nusselt number) exhibits scaling withRa2/7similar to non-rotating laboratory experiments. When the boundaries are stress free, the heat transport obeys ‘classical’ scaling (Ra1/3) for a limited range inRa, then appears to undergo a transition to a different law atRa≈ 4 × 107. Important dynamical differences between rotating and non-rotating convection are observed: aside from the (expected) differences in the boundary layers due to Ekman pumping effects, angular momentum conservation forces all plume structures created at flow-convergent sites of the heated and cooled boundaries to spin-up cyclonically; the resulting plume/cyclones undergo strong vortex-vortex interactions which dramatically alter the mean state of the flow and result in a finite background temperature gradient asRa→ ∞, holdingRa/Tafixed.
The motion of an ellipsoid in tube flow at low Reynolds numbers
Authors: Sugihara-Seki Masako
Published: April 2006

The motion of a rigid ellipsoidal particle freely suspended in a Poiseuille flow of an incompressible Newtonian fluid through a narrow tube is studied numerically in the zero-Reynolds-number limit. It is assumed that the effect of inertia forces on the motion of the particle and the fluid can be neglected and that no forces or torques act on the particle. The Stokes equation is solved by a finite element method for various positions and orientations of the particle to yield the instantaneous velocity of the particle as well as the flow field around it, and the particle trajectories are determined for different initial configurations. A prolate spheroid is found to either tumble or oscillate in rotation, depending on the particle–tube size ratio, the axis ratio of the particle, and the initial conditions. A large oblate spheroid may approach asymptotically a steady, stable configuration, at which it is located close to the tube centreline, with its major axis slightly tilted from the undisturbed flow direction. The motion of non-axisymmetric ellipsoids is also illustrated and discussed with emphasis on the effect of the particle shape and size.
The stability of three-dimensional time-periodic flows with ellipsoidal stream surfaces
Authors: Forster G. K. , Craik A. D. D.
Published: April 2006

Most steady flows with constant vorticity and elliptical streamlines are known to be unstable. These, and certain axisymmetric time-periodic flows, can be analysed by Floquet theory. However, Floquet theory is inapplicable to other time-periodic flows that yield disturbance equations containing a quasi-periodic, rather than periodic, function. A practical method for surmounting this difficulty was recently given by Bayly, Holm & Lifschitz. Employing their method, we determine the stability of a clas of three-dimensional time-periodic flows: namely, those unbounded flows with fixed ellipsoidal stream surfaces and spatially uniform but time-periodic strain rates. Corresponding, but bounded, flows are those within a fixed ellipsoid with three different principal axes. This is perhaps the first exact stability analysis of non-reducibly three-dimensional and time-dependent flows. Though the model has some artificial features, the results are likely to shed light on more complex systems of practical interest.
A similarity theory of locally homogeneous and isotropic turbulence generated by a Smagorinsky-type LES
Authors: Muschinski Andreas
Published: April 2006

A Kolmogorov-type similarity theory of locally homogeneous and isotropic turbulence generated by a Smagorinsky-type large-eddy simulation (LES) at very large LES Reynolds numbers is developed and discussed. The underlying concept is that the LES equations may be considered equations of motion of specific hypothetical fully turbulent non-Newtonian fluids, called ‘LES fluids’. It is shown that the length scalels=csδ, which scales the magnitude of the variable viscosity in a Smagorinsky-type LES, is the ‘Smagorinsky-fluid’ counterpart of Kolmogorov's dissipation length$\eta = v^{3/4}\epsilon^{-1/4}$for a Newtonian fluid where ν is the kinematic viscosity and ε is the energy dissipation rate. While in a Newtonian fluid the viscosity is a material parameter and the length ν depends on ε, in a Smagorinsky fluid the lengthlsis a material parameter and the viscosity depends on ε. The Smagorinsky coefficientcsmay be considered the reciprocal of a ‘microstructure Knudsen number’ of a Smagorinsky fluid. A combination of Lilly's (1967) cut-off model with two well-known spectral models for dissipation-range turbulence (Heisenberg 1948; Pao 1965) leads to models for the LES-generated Kolmogorov coefficient αLESas a function ofcs. Both models predict an intrinsic overestimation of αLESfor finite values ofcs. Forcs= 0.2 Heisenberg's and Pao's models provide αLES= 1.74 (16% overestimation) and αLES= 2.14 (43% overestimation), respectively, if limcs→ (αLES) = 1.5 isad hocassumed. The predicted overestimation becomes negligible beyond aboutcs= 0.5. The requirementcs> 0.5 is equivalent to Δ < 2ls. A similar requirement,L< 2η whereLis the wire length of hot-wire anemometers, has been recommended by experimentalists. The value of limcs→ (αLES) for a Smagorinsky-type LES at very large LES Reynolds numbers is not predicted by the models and remains unknown. Two critical values ofcsare identified. The first criticalcsis Lilly's (1967) value, which indicates thecsbelow which finite-difference-approximation errors become important; the second criticalcsis the value beyond which the Reynolds number similarity is violated.
Transport in lungs and branched estuaries
Authors: Smith Ronald
Published: April 2006

Longitudinal mass transport in branched oscillatory flows is greater than in non-branched oscillatory flows. Here a derivation is given of a longitudinal diffusion equation which governs the long-term mass transport when there is perfect synchronism of the flow in adjacent branches. An explicit formula is obtained for the shear dispersion coefficient (effective longitudinal diffusion) when a sinusoidal flow excursion crosses a junction in geometrically self-similar flows with negligible secondary flow. A single junction crossing can be sufficient to double the shear dispersion as compared to an unbranched flow at the same frequency.