1,290 research outputs found

    The Aspergillus niger faeB gene encodes a second feruloyl esterase involved in pectin and xylan degradation and is specifically induced in the presence of aromatic compounds

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    The faeB gene encoding a second feruloyl esterase from Aspergillus niger has been cloned and characterized. It consists of an open reading frame of 1644 bp containing one intron. The gene encodes a protein of 521 amino acids that has sequence similarity to that of an Aspergillus oryzae tannase. However, the encoded enzyme, feruloyl esterase B (FAEB), does not have tannase activity. Comparison of the physical characteristics and substrate specificity of FAEB with those of a cinnamoyl esterase from A. niger [Kroon, Faulds and Williamson (1996) Biotechnol. Appl. Biochem. 23, 255-262] suggests that they are in fact the same enzyme. The expression of faeB is specifically induced in the presence of certain aromatic compounds, but not in the presence of other constituents present in plant-cell-wall polysaccharides such as arabinoxylan or pectin. The expression profile of faeB in the presence of aromatic compounds was compared with the expression of A. niger faeA, encoding feruloyl esterase A (FAEA), and A. niger bphA, the gene encoding a benzoate-p-hydroxylase. All three genes have different subsets of aromatic compounds that induce their expression, indicating the presence of different transcription activating systems in A. niger that respond to aromatic compounds. Comparison of the activity of FAEA and FAEB on sugar-beet pectin and wheat arabinoxylan demonstrated that they are both involved in the degradation of both polysaccharides, but have opposite preferences for these substrates. FAEA is more active than FAEB towards wheat arabinoxylan, whereas FAEB is more active than FAEA towards sugar-beet pectin

    Identification of critical time‐consuming student support activities in e‐learning

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    Higher education staff involved in e‐learning often struggle with organising their student support activities. To a large extent this is due to the high workload involved with such activities. We distinguish support related to learning content, learning processes and student products. At two different educational institutions, surveys were conducted to identify the most critical support activities, using the Nominal Group Method. The results are discussed and brought to bear on the distinction between content‐related, process‐related and product‐related support activities

    Photoinduced two-proton knockout and ground-state correlations in nuclei

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    A factorized and analytical form for the A(γ\gamma,pp) and A(e,e'pp) cross section is proposed. In the suggested scheme the two-proton knockout cross sections can be directly analyzed in terms of the ground-state correlation functions. Central, spin-spin and tensor correlations are considered. In the longitudinal channel, the (e,e'pp) cross section is predicted to exhibit a peculiar sensitivity to ground-state correlation effects.Comment: 11 pages in REVtex with embedded psfigure

    Navigating expert skepticism and consumer distrust: rethinking the barriers to vehicle-to-grid (V2G) in the Nordic region

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    Vehicle-to-grid (V2G) refers to a technology that could help make the electricity grid more effective, reduce the cost of ownership of electric vehicles (EVs), and help integrate intermittent renewable energy sources. However, despite these advantages, implementation and even knowledge of the technology is not widespread. In order to explore why, we ask the question: what are the barriers that V2G currently faces? To provide an answer, the authors conducted 227 semi-structured interviews with transportation and electricity experts from 201 institutions across seventeen cities within the a market currently experimenting with electric mobility and V2G, the Nordic region. Results show that there is an extensive range of barriers facing V2G, with experts suggesting in total 35 categories of barriers. While the literature espouses substantial benefits of V2G, the experts interviewed generally displayed skepticism of the benefits and necessity of V2G in the Nordics. We categorized the top nine discussed barriers into four clusters. These clusters focused on the experts’ skepticism of the benefits of V2G, consumer acceptance, economic viability, and regulatory structure for V2G participation. We conclude the paper with policy implications and suggestions for future research

    Rethinking the spatiality of Nordic electric vehicles and their popularity in urban environments: moving beyond the city?

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    With a global transition to electric vehicles (EVs) slowly gaining traction, it is expedient to move the debate to issues connected to geography, space, and place. One of these emerging issues is the uptake of EVs in rural areas. This paper provides a spatial state of affairs in the Nordic region and it explores how EVs are perceived and argued to fit within rural-suburban-urban categories by users and potential adopters. To do so, it draws on a mix of original and secondary data: (1) a randomized survey among 4322 respondents, (2) 227 expert interviews, (3) eight focus groups conducted across Iceland, Denmark, Sweden, Finland and Norway, and (4) geographically mapped municipal level vehicle registrations across Norway and Sweden. This data shows that while the uptake primarily takes place in (sub)urban regions, EVs are used in rural environments, partly for self-sufficiency reasons. After acknowledging that individual choices and circumstances dictate final purchase decisions, the paper concludes that planners and researchers should be aware off and, if possible, prevent that a skewed urbanized popularity keeps people elsewhere from looking at EVs as a viable option

    The demographics of decarbonizing transport: the influence of gender, education, occupation, age, and household size on electric mobility preferences in the Nordic region

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    Many researchers, policymakers and other stakeholders have explored and supported efforts to transition towards more sustainable forms of low-carbon mobility. Often, discussion will flow from a narrow view of consumer perceptions surrounding passenger vehicles—presuming that they act in rationalist, instrumental, and predictable patterns. In this paper, we hold that a better understanding of the social and demographic perceptions of electric vehicles (compared to other forms of mobility, including conventional cars) is needed. We provide a comparative and mixed methods assessment of the demographics of electric mobility and stated preferences for electric vehicles, drawing primarily on a survey distributed to more than 5,000 respondents across Denmark, Finland, Iceland, Norway and Sweden. We examine how gender influences preferences; how experience in the form of education and occupation shape preferences; and how aging and household size impact preferences. In doing so we hope to reveal the more complex social dynamics behind how potential adopters consider and calculate various aspects of conventional mobility, electric mobility, and vehicle-to-grid systems. In particular, our results suggest that predominantly men, those with higher levels of education in full time employment, especially with occupations in civil society or academia, and below middle age (30 to 45), are the most likely to buy them. However, our analysis also reveals other market segments where electric vehicles may take root, e.g. among higher income females and retirees/pensioners. Moreover, few respondents were orientated towards V2G, independent of their demographic attributes. Our empirical results can inform ongoing discussions about energy and transport policy, the drivers of environmental change, and deliberations over sustainability transitions
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