Pentachlorophenol,polychlorodibenzodioxin and polychlorodibenzofuran in eggs from hens exposed to contaminated wood shavings

Laying hens may be exposed to pentachlorophenol (PCP) present in bedding materials derived from treated timber. As a result, this chemical and its contaminants or degradation products, such as polychlorodibenzodioxins (PCDDs) and polychlorodibenzofurans (PCDFs), may be present in eggs. The litter-to-eggs transfer and depletion of these compounds were studied in a flock of laying hens reared on contaminated wood shavings. PCP determination was carried out via high resolution gas chromatography coupled to low resolution mass spectrometry/mass spectrometry (HRGC–LRMS/MS); PCDDs and PCDFs were quantified by HRGC–HRMS (SIM). After substitution of the litter contaminated with PCDDs and PCDFs at an average of 50 pg WHO-TE g^?1 and with PCP at 15 µg g^?1, pooled eggs from six selected hens were sampled twice a month for the depletion study. At steady state, PCDDs and PCDFs showed a transfer ratio of 0.9; for PCP it was 0.03. PCP concentration in eggs (500 ng g^?1 whole weight) fell sharply the second week after exposure withdrawal; for PCDDs and PCDFs (47 pg WHO-TE g^?1 fat, at day 0), the overall TEQ half-life was estimated at an average of 3.8 weeks. Due to differences in toxicokinetics (a faster depletion), PCP does not appear to be a suitable marker of PCDD and PCDF violative levels. However, the prominent analytical contribution of H₇CCD and O₈CCD in the contamination profile may help to trace the source of contamination. Among congeners, 2,3,7,8 T₄CDF exhibited a different depletion pattern, indicating a possible mechanism of active transport.     

Ice accretion on superhydrophobic aluminum surfaces under low-temperature conditions

An icephobic surface is always desirable for high voltage overhead transmission lines to reduce ice formation on their aluminum surface, especially in a low temperature and high humidity environment. This work studied the effects of two hydrophobic coatings when applied on aluminum surfaces under cold and raining conditions in an artificial climatic chamber. Compared with bare hydrophilic aluminum surfaces, the aluminum surfaces coated with hydrophobic room temperature vulcanized silicone rubber (RTV SR) did resist ice formation but was covered by a layer of ice after 30 min of spraying supercooled water. However, a superhydrophobic coating can largely prevent ice formation on the surface except a few ice growth spots at a working temperature of − 6 °C. Furthermore, such coating keeps average water contact angles larger than 150° even at a working temperature of − 10 °C. This highly icephobic performance of the above samples is mainly attributed to the superhydrophobic property of the coating, which was obtained on micronanoscale structured aluminum surfaces after the low surface-energy stearic acid treatment.     

Cysteine 467 of the ASCT2 Amino Acid Transporter Is a Molecular Determinant of the Antiport Mechanism

The plasma membrane transporter ASCT2 is a well-known Na⁺-dependent obligatory antiporter of neutral amino acids. The crucial role of the residue C467 in the recognition and binding of the ASCT2 substrate glutamine, has been highlighted by structure/function relationship studies. The reconstitution in proteoliposomes of the human ASCT2 produced in P. pastoris is here employed to unveil another role of the C467 residue in the transport reaction. Indeed, the site-directed mutant C467A displayed a novel property of the transporter, i.e., the ability of mediating a low but measurable unidirectional transport of [³H]-glutamine. This reaction conforms to the main features of the ASCT2-mediated transport, namely the Na⁺-dependence, the pH dependence, the stimulation by cholesterol included in the proteoliposome membrane, and the specific inhibition by other common substrates of the reconstituted human ASCT2. Interestingly, the WT protein cannot catalyze the unidirectional transport of [³H]-glutamine, demonstrating an unspecific phenomenon. This difference is in favor of a structural conformational change between a WT and C467A mutant that triggers the appearance of the unidirectional flux; this feature has been investigated by comparing the available 3D structures in two different conformations, and two homology models built on the basis of hEAAT1 and GLT_Ph.     

Organocatalytic Enantioselective Transfer Hydrogenation of β‐Amino Nitroolefins

The asymmetric organocatalytic transfer hydrogenation of β‐acylamino and β‐tert‐butyloxycarbonylamino nitroolefins has been successfully realised in excellent enantioselectivities and yields (up to >99% ee, 97% yield) with a simple thiourea catalyst and a Hantzsch ester as hydrogen source, giving a direct access to enantiomerically pure β‐amino nitroalkanes.

     

采用超憎水性涂层缓解导线表面覆冰的实验研究

输电导线表面覆冰可能会导致断线、倒塔等安全事故,严重威胁着输电网络的安全可靠运行,本文探索防覆冰方法,通过化学刻蚀及涂覆低表面能物质的方法,在导线表面制备了超憎水涂层,并在覆冰模拟实验室里观察了超憎水涂层对导线表面覆冰的影响。试验现象表明,超憎水涂层可以增大导线表面的水滴接触角(CA),减小冰与导线之间的作用力,在一定程度上可以抑制和缓解铝导线表面覆冰的形成和增长,可用于导线防冰工作中。     

Use of β‐cyclodextrin in the dyeing of polyester with low environmental impact

In this paper, the effect of β‐cyclodextrin as an additive in the dyeing of polyester with disperse dyes, as a substitute for a commercial surfactant commonly used, was explored with the aim of reducing the environmental impact of the exhausted baths. Using a chemometric approach, a small group of dyes was selected as a ‘training set’ to be representative of a larger series of dyes with a similar structure. The selected dyes were synthesised and applied to the dyeing of polyester fibres under various conditions. The technological properties of the dyed samples were measured. The results showed that β‐cyclodextrin can satisfactorarily be used as an additive in dyebaths for polyester without the addition of other auxiliaries, with a positive environmental impact. Solubility isotherms evidenced dye–β‐cyclodextrin interactions. The formation of inclusion complexes did not produce negative effects on the dyeing performance. Light fastness values were modelled as a function of the structure by the chemometric partial least squares method and the established model was used to predict the fastness of dyes of analogous structure, not yet explored.     

New Platinum(II) Complexes Affecting Different Biomolecular Targets in Resistant Ovarian Carcinoma Cells

Resistance to platinum-based anticancer drugs represents an important limit for their clinical effectiveness and one of the most important field of investigation in the context of platinum compounds. From our previous studies, Pt^II complexes containing the triphenylphosphino moiety have been emerging as promising agents, showing significant cytotoxicity to resistant ovarian carcinoma cells. Two brominated triphenylphosphino trans-platinum derivatives were prepared and evaluated on human tumor cell lines, sensitive and resistant to cisplatin. The new complexes exert a notable antiproliferative effect on resistant ovarian carcinoma cells, showing a remarkable intracellular accumulation and the ability to interact with different intracellular targets. The interaction with DNA, the collapse of mitochondrial transmembrane potential, and the impairment of intracellular redox state were demonstrated. Moreover, a selectivity towards the selenocysteine of thioredoxin reductase was observed. The mechanism of action is discussed with regard to the resistance phenomenon in ovarian carcinoma cells.