The three-dimensional structure of 3, 3', 5'-trichloro-4-methoxybiphenyl, a "coplanar" polychlorinated biphenyl (PCB) derivative

The crystal structure of a "coplanar" polychlorinated biphenyl (PCB) derivative, 4-methoxy-3, 3', 5'-trichlorobiphenyl (C13H9Cl3O), is described. The torsion angle of the title compound is 41.31(07) degrees, which is in good agreement with the calculated torsion angle of 38.2 degrees in aqueous solution.     

Wolfgang Priester: from the big bounce to the $\Lambda$-dominated universe

Wolfgang Priester (1924–2005) was one of Germany’s most versatile and quixotic astrophysicists, reinventing himself successively as a radio astronomer, space physicist and cosmologist, and making a lasting impact on each field. We focus in this personal account on his contributions to cosmology, where he will be most remembered for his association with quasars, his promotion of the idea of a nonsingular “big bounce” at the beginning of the current expansionary phase, and his recognition of the importance of dark energy (Einstein’s cosmological constant Λ) well before this became the standard paradigm in cosmology. In memoriam Wolfgang Priester, 22 April 1924 – 9 July 2005     

Social experience during adolescence influences how male zebra finches (Taeniopygia guttata) group with conspecifics

Group-living animals rely on social skills which ensure beneficial interaction and prevent harmful ones with conspecifics. In a previous experiment, we demonstrated that male zebra finches reared in groups during adolescence show consistently less courtship and aggressive behaviour as adults than pair-reared males. Here we tested whether such differences affect how they group with conspecifics, as an indicator of their social integration. Zebra finches were kept in pairs (male–female or male–male) or mixed-sex groups (three males and three females) during adolescence and were introduced to an established group of unknown conspecifics during adulthood. Male courtship and aggressive behaviour were quantified directly after introduction to the group and 48 h later. At the same time, male position in relation to other birds and the number of birds in proximity were recorded. Males that grew up in a small mixed-sex group during adolescence spent more time within groups, were observed in bigger groups and lost less weight than males raised in pairs, indicating that an enriched social environment during early development may facilitate social integration. However, we observed no differences in courtship and aggressive behaviour that could predict the differences in grouping behaviour of pair- and group-reared males. We discuss alternative explanations for the difference in grouping and how to test these in future research.     

Synthesis of mono- and dimethoxylated polychlorinated biphenyl derivatives starting from fluoroarene derivatives

Environmental Science and Pollution Research - Polychlorinated biphenyls (PCBs) are environmental pollutants implicated in a variety of adverse health effects, including cancer and noncancer...     

Assessment of the disposition of chiral polychlorinated biphenyls in female mdr 1a/b knockout versus wild-type mice using multivariate analyses

Polychlorinated biphenyls (PCBs) are present in the environment as complex mixtures, which make it challenging to identify PCB congeners that may be subject to active transport processes. Here we employ a transgenic mouse model in combination with multivariate analyses to investigate if chiral PCBs 91, 95, 132, 136, 149, 174, 176 and 183 are subject to active (enantioselective) transport by multidrug resistance (MDR) transporters. A synthetic PCB mixture containing these congeners was administered orally to female FVB or mdr1a/1b knockout mice. Due to the short half-life of chiral PCB congeners, mice were euthanized after 24 h and PCB concentrations and enantiomeric fractions were determined in selected tissues and excreta. Principal component analysis did not reveal differences between wild-type and mdr1a/1b knockout mice. However, Hotelling T²-test revealed significantly lower PCB concentrations and a more pronounced enantiomeric enrichment in the adipose tissue of mdr1a/1b knockout mice. These differences are due to higher body weights and higher fecal fat contents of mdr1a/1b knockout mice. Analysis of the enantiomeric fractions of PCBs 91, 95, 136, 149 and 174 showed a significant enantiomeric enrichment for all five congeners in wild-type and mdr1a/1b knockout mice. Overall, by studying a PCB mixture in a transgenic mouse model in combination with a multivariate data reduction approach, PCBs 91, 95, 136, 149 and 174 could be excluded as substrates of multidrug resistance transporters 1a/b.     

Reactions of cloned poplars to air pollution

Ozone-induced changes in ethylene production, ACC oxidase activity and the contents of ACC, MACC and free PAs were studied inPopulus nigra L. cv. Loenen with high ozone sensitivity as judged by the degree of chlorophyll degradation and premature leaf abscission. Ethylene production, ACC oxidase activity, ACC content and MACC levels were induced by the one-, two-, and three-week ozone exposure (36±9 ppb O₃ for 11 hours a day). In addition, increases in PA levels, especially in spermidine, were measured in ozone treated plants. The role of free PAs and MACC synthesis as possible antisenescence reactions is discussed.     

Open workshops as sites of innovative socio-economic practices: approaching urban post-growth by assemblage theory

ABSTRACT

Current debates on knowledge-based and creative locational development have come to deal with small urban places of novelty that formerly remained unnoticed. A plethora of new forms of producing and working recently emerged in unplanned and uncoordinated ways, bearing odd names such as FabLabs, Open Worklabs, RealLabs, Open Design Cities, Techshops, Repair Cafés, and more (Smith, A., M. Fressoli, D. Abrol, E. Arond, and A. Ely. 2017. Grassroots Innovation Movements. London: Routledge). Political initiatives have been taken by surprise; at the same time, standard epistemic tools of the social sciences and economics have been rendered unfit. More concise analytical reconstructions are needed to adequately capture the variety and complexity of these “labs”, their heterogeneous causation, their contingent proceedings, their surplus of latency, their peculiar power relations and their local embeddings. Urban social contexts have a strong triggering function as they help to re-configure older, and create new, combinations of heterogeneous social and economic agency. Meanwhile strong elements of grassroots innovation (Smith et al. 2017) have informed the formation of various models of alternative work and production. Taking the phenotype of open workshops as a revealing example, we take assemblage theory to describe the constitutive features of these new types of self-organised work, and the associated places of innovation. A fresh gaze on the complexity and open-endedness of socio-material formations may help to better understand the nature of emerging post-growth economies.