Aphid deterrence by glucose esters in glandular trichome exudate of the wild tomato,Lycopersicon pennellii

Settling of the potato aphid,Macrosiphum euphorbiae, on feeding membranes was deterred by methanolic leaf rinses ofLycopersicon pennellii, or of its F₁ with tomato,L. esculentum. The active compounds in theL. pennellii rinsates were identified as 2,3,4-tri-O-acylglucoses bearing short to medium chain length fatty acids. These compounds are localized in the glandular exudate of the type IV trichomes and may accumulate to levels in excess of 400 g/cm². In choice assays, purified glucose esters fromL. pennellii reduced aphid settling at concentrations as low as 25 g/cm²; at concentrations of 150 g/cm² or more, all aphids avoided treated areas. Glucose esters were also active in deterring aphid settling in no-choice assays. At 100 g/ cm², these esters resulted in increased levels of mortality after 48 hr.     

Polychlorierte Biphenyle (PCB) in Lebensmitteln

Zusammenfassung Im Rahmen eines koordinierten Forschungsprogramms des BMFT wurde eine orientierende Studie an möglichst repräsentativen Stichproben durchgeführt. Trotz relativ großer Streubreiten zeichnen sich die Bereiche der wichtigsten Lebensmittelgruppen deutlich voneinander ab mit Mittelwerten um 0,005 /g für fettarme pflanzliche Grundnahrungsmittel, um 0,05 /g für pflanzliche Nahrungsfette, um 0,3 /g für Milch-, Käse und Butterfette, um 0,15 /g für sonstige Nahrungsfette von Landtieren, um 0,03 /g für Hühnereier und um 10 /g für Fischfett. Wichtet man die Gehalte entsprechend der durchschnittlichen Diät in der BRD, so ergibt sich eine tägliche PCB-Aufnahme von rund 29 aus tierischen Fetten und rund 6 aus den übrigen Lebensmitteln. Die Gesamtaufnahme von ca. 35 g pro Tag und capita entspricht etwa dem Wert, der von der WHO als ADI-Wert für HCB (Hexachlorbenzol) in Aussicht genommen wurde.

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Polychlorinated biphenyls (PCB) in foodThe situation in the Federal Republic of Germany

Summary In a coordinated research program of the Federal Ministry of Research and Technology (BMFT), a screening study was carried out with representative samples. In spite of rather large ranges of PCB concentrations, the most important food-stuffs show clearly defined clusters with mean values of approx. 0.005 /g in low fat food components of plant origin such as cereals or potatoes, approx. 0.05 /g in vegetable fats, approx. 0.3 /g in fat from milk, butter and cheese, approx. 0.15 gg/g in animal fat, approx. 0.03 in chicken eggs and approx. 10 /g in fish fat. Considering the mean diet in the FRG, a daily PCB intake of about 29 g from animal fat and of 6 from the other food-stuffs results. The total intake of about 35 g per day and capita is almost the same as the figure conditionally suggested by the WHO as the acceptable daily HCB (hexachlorobenzene) intake.

     

Wear resistant solid lubricant coating made from PTFE and epoxy

A composite coating of polytetrafluoroethylene and epoxy shows 100 × improvements in wear resistance as compared to either of its constituents alone and reduced friction coefficient under testing on a pin-on-disk tribometer. This coating is made by impregnating an expanded PTFE film with epoxy, which provides three unique functions: (1) the epoxy compartmentalizes the PTFE nodes, which is believed to reduce the wear of the PTFE, (2) the epoxy increases the mechanical properties such as elastic modulus and hardness, and (3) the epoxy provides a ready interface to bond the films onto a wide variety of substrates easily and securely. The experimental matrix had normal loads of 1–3 N, sliding speeds from 0.25 to 2.5 m/s, and used a 2.4 mm radius low carbon steel pin in a rotating pin-on-disk tribometer. The skived PTFE films had wear rates on the order of K=10^–3 mm³/Nm and friction coefficients around =0.2. Both the high density films (70 wt%PTFE) and low density films (50 wt% PTFE) had wear rates on the order of K=10^–6 mm³/Nm and friction coefficients around =0.15. The neat epoxy films showed significant scatter in the tribological measurements with wear-rates on the order of K=10^–4 mm³/Nm and friction coefficients around =0.40. The enhanced tribological behavior of these composites is believed to stem from the coatings ability to draw thin PTFE transfer films into the contact from the nodes of PTFE, which act like reservoirs. Nanoindentation mapping of the coatings and the transfer films supports this hypothesis, and accompanies scanning electron microscopy observations of the worn and unworn coatings.     

Feature Selection for Recognition of Online Handwritten Bangla Characters

Feature selection through optimization techniques provides an interesting approach to minimize computational time with enhanced prediction capability, and     

Lipid specificity and location of the sterol carrier protein-2 fatty acid-binding site: A fluorescence displacement and energy transfer study

Although it was recently recognized that sterol carrier protein-2 (SCP-2) interacts with fatty acids, little is known regarding the specificity of SCP-2 for long-chain fatty acids or branched-chain fatty-acid-like molecules. Likewise the location of the fatty-acid binding site within SCP-2 is unresolved. A fluorescent cis-parinaric acid displacement assay was used to show that SCP-2 optimally interacted with 14–22 carbon chain lipidic molecules: polyunsaturated fatty acids > monounsaturated, saturated > branched-chain isoprenoids > branched-chain phytol-derived fatty acids. In contrast, the other major fatty-acid binding protein in liver, fatty-acid binding protein (L-FABP), displayed a much narrower carbon chain preference in general: polyunsaturated fatty acids > branched-chain phytol-derived fatty acids > 14- and 16-carbon saturated > branched-chain isoprenoids. However, both SCP-2 and l-FABP displayed a very similar unsaturated fatty-acid specificity profile. The presence and location of the SCP-2 lipid binding site were investigated by fluorescence energy transfer. The distance between the SCP-2 Trp⁵⁰ and bound cis-parinaric acid was determined to be 40 Å. Thus, the SCP-2 fatty-acid binding site appeared to be located on the opposite side of the SCP-2 Trp⁵⁰. These findings not only contribute to our understanding of the SCP-2 ligand binding site but also provide evidence suggesting a potential role for SCP-2 and/or L-FABP in metabolism of branched-chain fatty acids and isoprenoids.