Nocturnal Bees are Attracted by Widespread Floral Scents

Flower localization in darkness is a challenging task for nocturnal pollinators. Floral scents often play a crucial role in guiding them towards their hosts. Using common volatile compounds of floral scents, we trapped female nocturnal Megalopta-bees (Halictidae), thus uncovering olfactory cues involved in their search for floral resources. Applying a new sampling method hereby described, we offer novel perspectives on the investigation of nocturnal bees.     

Conformationally pre-organized and pH-responsive flat dendrons: synthesis and self-assembly at the liquid-solid interface

Efficient Cu-catalyzed 1,3-dipolar cycloaddition reactions have been used to prepare two series of three regioisomers of G-1 and G-2 poly(triazole-pyridine) dendrons. The G-1 and G-2 dendrons consist of branched yet conformationally pre-organized 2,6-bis(phenyl/pyridyl-1,2,3-triazol-4-yl)pyridine (BPTP) monomeric and trimeric cores, respectively, carrying one focal and either two or four peripheral alkyl side chains. In the solid state, the conformation and supramolecular organization were studied by means of a single crystal X-ray structure analysis of one derivative. At the liquid-solid interface, the self-assembly behavior was investigated by scanning tunneling microscopy (STM) on graphite surfaces. Based on the observed supramolecular organization, it appears that the subtle balance between conformational preferences inherent in the dendritic backbone on the one side and the adsorption and packing of the alkyl side chains on the graphite substrate on the other side dictate the overall structure formation in 2D.     

恩格利殊的压花辊技术

公司概况 恩格利殊公司成立于1892年,拥有员工200多名,厂区面积6万m2,厂房面积4．5万m2,公司的产品主要有压花辊、印刷辊、网型辊等,公司通过了ISO9001：2000认证。2012年公司共制作71．3万根压花辊。     

Time-variant reliability profiles for steel girder bridges

Evaluation of existing steel bridges becomes more important due to natural aging, increasing load spectra, deterioration caused by corrosion, and other problems. In the result, bridge structures exposed to aggressive environmental conditions are subjected to time-variant changes of resistance. Therefore, there is a need for evaluation procedures for an accurate prediction of the load carrying capacity and reliability of bridge structures, in order to make rational decisions about repair, rehabilitation, and expected life-cycle costs. The objective of this paper is to develop time-variant reliability models for steel girder bridges. Traditional methods based on deterministic analysis do not reveal the actual load carrying capacity of the structure. The proposed approach is based on reliability analysis of components and structural systems. The study involves the selection of representative structures, formulation of limit state functions, development of load models, development of resistance models for corroded steel girders, development of the reliability analysis method, reliability analysis of selected bridges, and development of the time-dependant reliability profiles including deterioration due to corrosion. The results of the study can be used for a better prediction of the service life of deteriorating steel girder bridges, and development of optimal reliability-based maintenance strategies.     

Anion conducting polymers based on ether linked polybenzimidazole (PBI-OO)

Anion conducting polymers are potentially interesting for fuel cells, electrochemical pumps, and dye sensitized solar cells. Ether-containing polybenzimidazoles (PBI-OO and PBI-OPO) were synthesized and turned into anion conducting polymers by methylation. The thermal stability was shown to depend on the polymer structure and degree of methylation (dom). Tensile strength and modulus decrease between 50% and 75% dom, but stay constant or slightly increase over 75% dom again. At 65 °C, hydroxide, iodide, chloride, carbonate and bicarbonate conductivities of 0.1, 0.6, 19, 20, 31 mS/cm were obtained, respectively. The low hydroxide conductivity is due to the formation of a C–O bond in position 2 of the imidazolium, which reduces the number of free ions and is known to lead to imidazolium ring opening and further degradation steps. The effect of introduction of phenoxy groups into the main chain on the charge distribution, especially on position 2 and the methyl groups (positive charge on the methyl groups decreases the thermal stability), as well as on the ion bonding was thoroughly investigated by DFT calculations and correlated with experimental data.     

Calcium effect on mechanical properties of model cell walls and apple tissue

Bacterial cellulose alone, with pectin added and with both pectin and xyloglucan added were produced as models for plant cell walls. The artificial cell wall materials and natural apple tissue were treated with calcium and then subjected to tests of mechanical properties; a tension test for the artificial cell wall materials and a compression test for the apple tissue. It was found that pectin and xyloglucan had a significant effect on the mechanical properties of artificial cell wall materials, making them more extensible. A high concentration of calcium increased the failure strain and decreased the failure stress of these materials. Treatment of apple tissue with calcium had similar effects on the failure stress and the secant modulus, whereas the differences of failure strain and work to failure resulted in behaviour different from that of the artificial material.     

Aseptically packaged UHPH-treated apple juice: Safety and quality parameters during storage

Ultra-high pressure homogenization (UHPH) at 300 MPa and 4 °C inlet temperature were used to preserve apple juice, and shelf-life evaluation of aseptically packaged juice was investigated. After processing Tetra Brik containers were stored at temperatures of 4, 10, 20 and 30 °C during 60 days. In this article, the effect of processing on the spoilage inactivation was evaluated after processing and during the storage trial. Non-germinated and germinated spores were found in the UHPH-treated juice, being an inactive population during storage. Patulin content was also not modified by UHPH processing, but a significant decrease was observed during storage at 30 °C (P < 0.05). Polyphenoloxidase (PPO) and pectinmethylesterase (PME) activity was not found after UHPH-processing and during storage.A kinetic study of post-processing quality loss was conducted. Vitamin C, chlorogenic acid, total polyphenols and color change were measured during storage study and were used to model the UHPH-treated apple juice shelf-life. Loss of vitamin C was correlated with the hydroxymethylfurfural (HMF) accumulation (0.59, P < 0.05). A limiting quality parameter was polyphenolic content. UHPH-treated apple juice stored at 4 °C was found to show a shelf-life for about 21 months by preserving the color characteristics of the juice with low HMF accumulation. From 15 °C changes in quality parameters were more evident.     

Identification of phenolic constituents of Cytisus multiflorus

The phenolic composition of the ethanolic extract obtained from the flowers of the medicinal plant Cytisus multiflorus has been elucidated by high performance liquid chromatography, electrospray mass spectrometry and nuclear magnetic resonance analysis. The extract was mainly composed of flavones, including the common chrysin, orientin, luteolin-5-O-glucoside, luteolin-7-O-glucoside, apigenin and apigenin-7-O-glucoside, which appeared as minor components. The major flavone in the extract was chrysin-7-O-β-d-glucopyranoside, and it also contained moderate amounts of a dihydroxyflavone isomer of chrysin, as well as of 2″-O-pentosyl-6-C-hexosyl-luteolin, 2″-O-pentosyl-8-C-hexosyl-luteolin and 6″-O-(3-hydroxy-3-methylglutaroyl)-2″-O-pentosyl-C-hexosyl-apigenin, which are not commonly found in the Fabaceae family. Other novel phenolic compounds found in the ethanolic extract of C. multiflorus comprised the flavones 2″-O-pentosyl-6-C-hexosyl-apigenin, 2″-O-pentosyl-8-C-hexosyl-apigenin and 6″-O-(3-hydroxy-3-methylglutaroyl)-2″-O-pentosyl-C-hexosyl-luteolin. The assessment of the biological activities of the main compounds of this extract are now keen, in order to determine their relevance in the beneficial properties of the plant.     

Multicenter Collaborative Trial Evaluation of a Method for Detection of Human Adenoviruses in Berry Fruit

The qualitative performance characteristics of a qPCR-based method to detect human adenoviruses in raspberries were determined through a collaborative trial involving 11 European laboratories. The method incorporated a sample process control (murine norovirus) and an internal amplification control. Trial sensitivity or correct identification of 25-g raspberry samples artificially contaminated with between 5?×?10² and 5?×?10⁴?PFU was 98.5%; the accordance and concordance were 97.0%. The positive predictive value was 94.2%. The trial specificity or percentage correct identification of non-artificially contaminated samples was 69.7%; the accordance was 80.0% and the concordance was 61.7%. The negative predictive value was 100%. Application of a method for the detection of human adenoviruses in food samples could be useful for routine monitoring for food safety management. It would help to determine if a route of contamination exists from human source to food supply chain which pathogenic viruses such as norovirus and hepatitis A virus could follow.