949 resultados para isolated co-cultures
Resumo:
A one-step synthesis of (IIb), an isomerization product of 7-methoxychromano3,4-disoxazole, from (III) is reported.
Resumo:
The presence of an indole oxidase (indole: O2 oxidoreductase) was detected in the leaf extracts of Tecoma stans. The end product of the reaction was identified as anthranil. Formylaminobenzaldehyde, and o- aminobenzaldehyde were detected as intermediates in the overall conversion. Oxygen-uptake studies established that 3 atoms of oxygen were consumed in the formation of anthranil form I molecule of indole. The enzyme showed an absolute requirement for FAD and Cu2+ for maximum activity. FMN was ineffective as a cofactor. The enzyme had an optimum pH of 5.0. Inhibition studies with GSH and p-chloromericuribenzoate showed that a sulfhydrylcupric-ion complex at the active centre is highly essential.
Resumo:
We present a measurement of the top quark mass with t-tbar dilepton events produced in p-pbar collisions at the Fermilab Tevatron $\sqrt{s}$=1.96 TeV and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb$^{-1}$, are selected as t-tbar candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles ($\phi_{\nu_1},\phi_{\nu_2}$) of neutrinos and reconstruct the top quark mass for each $\phi_{\nu_1},\phi_{\nu_2}$ pair by minimizing a $\chi^2$ function in the t-tbar dilepton hypothesis. We assign $\chi^2$-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated t-tbar and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of $165.5^{+{3.4}}_{-{3.3}}$(stat.)$\pm 3.1$(syst.) GeV/$c^2$.
Resumo:
ORANGE red and amorphous peroxy-titanium complexes of oxalic, malonic and maleic acids1-3, when vacuum-dried, have co-ordinated water molecules firmly bonded to the central titanium atom as shown in formula (I). The peroxy-oxygen from these compounds is slowly lost even at room temperature because of the strained peroxy-group3,4. The compounds, when kept at 95°-100°C. for about three days, give deperoxygenated compounds of the type (II). However, a sample of peroxy-titanium oxalate sealed in a glass tube lost all its peroxy-oxygen in about four years and gave a white crystalline basic oxalate (II). The amorphous nature of the compounds may be due to random hydrogen bonding in the complexes. The crystallinity observed in one of the deperoxygenated titanyl oxalates may be due to the rearrangement of the molecules during ageing for more than four years. The infra-red absorption of these compounds was studied to find out the effect of co-ordination and hydrogen bonding on the infra-red bands of the free water.
Resumo:
Phenol- and catechol-adapted sludges contained large numbers of the yeasts, Candida tropicalis and Trichosporon cutaneum. Both were able to grow on a variety of aromatic compounds and utilized phenol and catechol at a high rate. This property was inducible. The feasibility of using these yeasts for removing phenols from waste waters is suggested.
Resumo:
"In this study, for the first time, two distinct genetic lineages of Puumala virus (PUUV) were found within a small sampling area and within a single host genetic lineage (Ural mtDNA) at Pallasjarvi, northern Finland. Lung tissue samples of 171 bank voles (Myodes glareolus) trapped in September 1998 were screened for the presence of PUUV nucleocapsid antigen and 25 were found to be positive. Partial sequences of the PUUV small (S), medium (M) and large (L) genome segments were recovered from these samples using RT-PCR. Phylogenetic analysis revealed two genetic groups of PUUV sequences that belonged to the Finnish and north Scandinavian lineages. This presented a unique opportunity to study inter-lineage reassortment in PUUV; indeed, 32% of the studied bank voles appeared to carry reassortant virus genomes. Thus, the frequency of inter-lineage reassortment in PUUV was comparable to that of intra-lineage reassortment observed previously (Razzauti, M., Plyusnina, A., Henttonen, H. & Plyusnin, A. (2008). J Gen Virol 89, 1649-1660). Of six possible reassortant S/M/L combinations, only two were found at Pallasjarvi and, notably, in all reassortants, both S and L segments originated from the same genetic lineage, suggesting a non-random pattern for the reassortment. These findings are discussed in connection to PUUV evolution in Fermoscandia."
Resumo:
Plexins (plxn) are receptors of semaphorins (sema), which were originally characterized as axon guidance cues. Semaphorin-plexin signalling has now been implicated in many other developmental and pathological processes. In this thesis, my first aim was to study the expression of plexins during mouse development. My second aim was to study the function of Plexin B2 in the development of the kidney. Thirdly, my objective was to elucidate the evolutionary conservation of Plexin B2 by investigating its sequence, expression and function in developing zebrafish. I show by in situ hybridisation that plexins are widely expressed also in the non-neuronal tissues during mouse development. Plxnb1 and Plxnb2, for example, are expressed also in the ureteric epithelium, developing glomeruli and undifferentiated metanephric mesenchyme of the developing kidney. Plexin B2-deficient (Plxnb2-/-) mice die before birth and have severe defects in the nervous system. I demonstrate that they develop morphologically normal but hypoplastic kidneys. The ureteric epithelium of Plxnb2-/- kidneys has fewer branches and a lower rate of proliferating cells. 10% of the embryos show unilateral double ureters and kidneys. The defect in the branching is intrinsic to the epithelium as the isolated ureteric epithelium grown in vitro fails to respond to Glial-cell-line-derived neurotrophic factor (Gdnf). We prove by co-immunoprecipitation that Plexin B2 interacts with the Gdnf-receptor Ret. Sema4C, the Plexin B2 ligand, increases branching of the ureteric epithelium in controls but not in Plxnb2-/- kidney explants. These results suggest that Sema4C-Plexin B2 signalling modulates ureteric branching in a positive manner, possibly through directly regulating the activation of Ret. I cloned the zebrafish orthologs of Plexin B2, Plexin B2a and B2b. The corresponding proteins contain the conserved domains the B-subfamily plexins. Especially the expression pattern of plxnb2b recapitulates many aspects of the expression pattern of Plxnb2 in mouse. Plxnb2a and plxnb2b are expressed, for example, in the pectoral fins and at the midbrain-hindbrain region during zebrafish development. The nearly complete knockdown of Plexin B2a alone or together with the 45% knockdown of Plexin B2b did not interfere with the normal development of the zebrafish. In conclusion, my thesis reveals that plexins are broadly expressed during mouse embryogenesis. It also shows that Sema4C-Plexin B2 signalling modulates the branching of the ureteric epithelium during kidney development, perhaps through a direct interaction with Ret. Finally, I show that the sequence and expression of Plexin B2a and B2b are conserved in zebrafish. Their knockdown does not, however, result in the exencephaly phenotype of Plxnb2-/- mice.
Resumo:
The aim of this report is to discuss the role of the relationship type and communication in two Finnish food chains, namely the pig meat-to-sausage (pig meat chain) and the cereal-to-rye bread (rye chain) chains. Furthermore, the objective is to examine those factors influencing the choice of a relationship type and the sustainability of a business relationship. Altogether 1808 questionnaires were sent to producers, processors and retailers operating in these two chains of which 224 usable questionnaires were returned (the response rate being 12.4%). The great majority of the respondents (98.7%) were small businesses employing less than 50 people. Almost 70 per cent of the respondents were farmers. In both chains, formal contracts were stated to be the most important relationship type used with business partners. Although for many businesses written contracts are a common business practice, the essential role of the contracts was the security they provide regarding the demand/supply and quality issues. Relative to the choice of the relationship types, the main difference between the two chains emerged especially with the prevalence of spot markets and financial participation arrangements. The usage of spot markets was significantly more common in the rye chain when compared to the pig meat chain, while, on the other hand, financial participation arrangements were much more common among the businesses in the pig meat chain than in the rye chain. Furthermore, the analysis showed that most of the businesses in the pig meat chain claimed not to be free to choose the relationship type they use. Especially membership in a co-operative and practices of a business partner were mentioned as the reasons limiting this freedom of choice. The main business relations in both chains were described as having a long-term orientation and being based on formal written contracts. Typical for the main business relationships was also that they are not based on the existence of the key persons only; the relationship would remain even if the key people left the business. The quality of these relationships was satisfactory in both chains and across all the stakeholder groups, though the downstream processors and the retailers had a slightly more positive view on their main business partners than the farmers and the upstream processors. The businesses operating in the pig meat chain seemed also to be more dependent on their main business relations when compared to the businesses in the rye chain. Although the communication means were rather similar in both chains (the phone being the most important), there was some variation between the chains concerning the communication frequency necessary to maintain the relationship with the main business partner. In short, the businesses in the pig meat chain seemed to appreciate more frequent communication with their main business partners when compared to the businesses in the rye chain. Personal meetings with the main business partners were quite rare in both chains. All the respondent groups were, however, fairly satisfied with the communication frequency and information quality between them and the main business partner. The business cultures could be argued to be rather hegemonic among the businesses both in the pig meat and rye chains. Avoidance of uncertainty, appreciation of long-term orientation and independence were considered important factors in the business cultures. Furthermore, trust, commitment and satisfaction in business partners were thought to be essential elements of business operations in all the respondent groups. In order to investigate which factors have an effect on the choice of a relationship type, several hypotheses were tested by using binary and multinomial logit analyses. According to these analyses it could be argued that avoidance of uncertainty and risk has a certain effect on the relationship type chosen, i.e. the willingness to avoid uncertainty increases the probability to choose stable relationships, like repeated market transactions and formal written contracts, but not necessary those, which require high financial commitment (like financial participation arrangements). The probability of engaging in financial participation arrangements seemed to increase with long-term orientation. The hypotheses concerning the sustainability of the economic relations were tested by using structural equation model (SEM). In the model, five variables were found to have a positive and statistically significant impact on the sustainable economic relationship construct. Ordered relative to their importance, those factors are: (i) communication quality, (ii) personal bonds, (iii) equal power distribution, (iv) local embeddedness and (v) competition.
Resumo:
Nature-based tourism is one of the fastest growing tourism sectors at the moment. It is also the form of tourism that often benefits the economy of rural areas. In addition to state owned forests, nature-based tourism is in many countries situated in private forests, which are not owned by entrepreneurs themselves. Therefore, the ownership issues and property rights form central challenges for the business activities. The maintenance of good relationships between private forest owners and entrepreneurs, as well as combining their interests, becomes vital. These relationships are typically exceptionally asymmetrical, granting the forest owner unilateral rights regulating the business activities in their forests. Despite this, the co-operation is typically very informal and the existing economic compensation models do not necessarily cover all the forest owners’ costs. The ownership issues bring their own characteristics to the relationship. Therefore, we argue that different aspects of ownership, especially psychological ones, have to be more critically examined and taken into consideration in order to build truly successful relations between these parties. This is crucial for sustaining the business activities. The core of psychological ownership is the sense of possession. Psychological ownership can be defined as a state, in which individuals perceive the target of ownership, the object or idea, as “theirs”. The concept of psychological ownership has so far been mainly used in the context of professional organizations. In this research, it has been used to explain the relationships between private forest owners and nature-based entrepreneurs. The aim of this study is to provide new information concerning the effect of psychological ownership on the collaboration and to highlight the good practices. To address the complexity of the phenomenon, qualitative case study methods were adopted to understand the role of ownership at the level of subjective experience. The empirical data was based on 27 in-depth interviews with private forest owners and nature-based tourism entrepreneurs. The data was analysed by using the methods of qualitative analysis to construct different typologies to describe the essence of successful collaboration. As a result of the study, the special characteristics and the practical level expressions of the psychological ownership in the privately owned forest context were analysed. Four different strategies to perceive these ownership characteristics in co-operation relationships were found. By taking the psychological ownership into consideration via these strategies, the nature-based entrepreneurs aim to balance the co-operation relationship and minimise the risks in long term activities based on privately owned forests.
Resumo:
ALTHOUGH titanium is determined colorimetrically in aqueous sulphuric acid medium in presence of excess of hydrogen peroxide, the nature of the colour-forming species is not known definitely. Schwarz1 suggested that the colour was due to the peroxo-disulphato titanate anion [O 2Ti(SO4)2]2-. On the other hand, Jahr2 and later Gastinger3 considered that the colour of the compound was due to the peroxy titanyl cation [TiO2 aq.] 2+, and suggested the following equilibrium in solution: Schaeppi and Treadwell4 attributed the colour bo O2TiSO4 or [O2Ti(SO4)2]2-, whereas Babko and Volkova5 represented the coloured complex ion as [Ti(H 2O2)]4+. Mori, Shibata, Kyuno and Ito 6 regarded the coloured species as [TiO2 aq.]2+ or [Ti(OH)2 (H2O)(H2O2)] 2+, assuming the co-ordination number of titanium to be four. Thus, a variety of constitutions has been proposed to explain the colour-forming species of the titanium complex, based on the investigations carried out in dilute sulphuric acid medium, but the complex has not been isolated so far.
Resumo:
The ultrasonic degradation of poly (styrene-co-methyl methacrylate) (SMMA), poly (styrene-co-ethyl methacrylate) (SEMA) and poly (styrene-co-butyl methacrylate) (SBMA) copolymers of different compositions was studied. The copolymers were synthesized and NMR spectroscopy was used to determine the composition, and the glass transition temperatures were determined by DSC. The reactivity ratios were determined by the Kelen-Tudos method and it indicated that the copolymers were random. The effect of solvent, temperature and copolymer composition on the ultrasonic degradation rate of these copolymers was investigated. A model based on continuous distribution kinetics was employed to study the degradation kinetics. The degradation rate coefficients of the copolymers decreased with an increase in the styrene content in the copolymer. At any particular copolymer composition the rate of degradation follows the order: SBMA >SEMA > SMMA. Thermogravimetric analysis (TGA) of the copolymers was carried in order to assess their thermal stability. The same order of degradation was observed for the thermal degradation of the copolymers as that observed for ultrasonic degradation. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
Somatic embryogenesis (SE) is an asexual form of plant propagation that occurs in nature and mimics many of the events of sexual reproduction. Pinus sylvestris (L.) is an important source of timber in Northern Eurasia but it is recalcitrant to somatic embryogenesis. Several factors important for the success of the P. sylvestris embryogenic cultures have not been thoroughly investigated. In this study, we examined the effects of parental genotypes on the SE in P. sylvestris, the involvement of the gaseous plant growth regulator, ethylene in SE, and also biotic effects on somatic embryos as well as on seedlings. We tested parental effects on immature embryo initiation for different media, storage periods, and on the maturation process. Maternal effects were found to be crucial for SE in the absence of paternal effects. No maternal-paternal interaction was observed at any stage of somatic embryo production. Additionally the role of ethylene at different developmental stages of SE was investigated. Two ACC synthase genes, PsACS1 and PsACS2, were isolated and characterized. PsACS1 was expressed during the proliferation stage in all tested genotypes, whereas PsACS2 was only expressed in somatic embryos of each genotype. Ethylene production in embryos at stage 3 was significantly higher than the other stages. In a parallel study, the response of somatic embryos to fungal elicitors was investigated. Three fungi, a mutualistic ectomycorrhizal (ECM) fungus (Suillus bovinus), a weak Scots pine pathogen (Heterobasidion parviporum) and a strong pathogen (H. annosum) were used. The gene expression patterns for embryos exposed to the H. parviporum elicitor were found to be similar to that documented for S. bovinus among the tested genes. By contrast somatic embryos exposed to the H. annosum elicitor had a different pattern of regulation which was marked by a delayed response, and in some cases death of the embryos. Furthermore, interaction without direct contact between P. sylvestris seedlings and microbes (mutualistic and pathogenic fungus, cyanobacterium) were investigated. Several novel genes expressed in seedlings treated with ECM fungus were isolated which suggested that physical contact is not necessary for elicitation of host responses. The results suggest that somatic embryos and seedlings of P. sylvestris are genetically well equipped to respond to fungal elicitor/exudates and could serve as a suitable model for reproducible molecular studies in conifer tree patho- and symbiotic systems.
Resumo:
1,6-hexanediol diacrylate (HDDA) and methyl methacrylate (MMA) were copolymerized in different weight ratios using UV light induced photo-polymerization to give poly(HDDA-co-MMA). Differential scanning calorimetry shows that copolymer was formed. The thermogravimetric and differential scanning calorimetric studies with different heating rates were carried out on these copolymers to understand the nature of degradation and to determine its kinetics. Different kinetic models were adopted to evaluate various parameters like the activation energy, the order, and the frequency factor. These analyses are important to study the binder removal from 3D-shaped ceramic objects made by techniques like Solid free form fabrication. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2444-2453, 2010.
Resumo:
Seeking to challenge the belief that within-West cultural differences should be seen as insignificant in organisations, this paper seeks to demonstrate how two given Western European ‘organising cultures’ (i.e. Finnish culture and French culture, as they are expressed in the process of organising) can contrast, if not conflict, with each other. Further, it aims to help the reader realise what kinds of fundamental ‘cultural antagonisms’ these contrasting organising behaviours may come from, to help her/him understand ‘the other culture’ better, and thus allow for a first step towards an improvement of Finnish-French intercultural interactions in organisational contexts. After shortly introducing what should be understood here as ‘cultural antagonisms’, the paper addresses four fundamental Finnish-French antagonisms, regarding the vision of the organisation (‘functionalist vs. personalist’), the relative importance of ‘consensus vs. dissensus’, the typical trade-off between reliability and flexibility, and the striking differences in communication, respectively. These four fundamental antagonisms are found to be closely interrelated and integrated, serving as explanation, justification and legitimisation for each other. That does not mean, however, that differences, however striking they may be, should merely be a threat to co-operation: some implications introduced at the end of the paper suggest that, provided people are aware of them, cultural antagonisms can also be seen as opportunities for a more fruitful work interaction.