Male Phyllotreta striolata (F.) Produce an Aggregation Pheromone: Identification of Male-specific compounds and Interaction with Host Plant Volatiles

The chrysomelid beetle Phyllotreta striolata is an important pest of Brassicaceae in Southeast Asia and North America. Here, we identified the aggregation pheromone of a population of P. striolata from Taiwan, and host plant volatiles that interact with the pheromone. Volatiles emitted by feeding male P. striolata attracted males and females in the field. Headspace volatile analyses revealed that six sesquiterpenes were emitted specifically by feeding males. Only one of these, however, elicited an electrophysiological response from antennae of both sexes. A number of host plant volatiles, e.g., 1-hexanol, (Z)-3-hexen-1-ol, and the glucosinolate hydrolysis products allyl isothiocyanate (AITC), 3-butenyl isothiocyanate, and 4-pentenyl isothiocyanate also elicited clear responses from the antenna. The active male-specific compound was identified as (+)-(6R,7S)-himachala-9,11-diene by chiral stationary phase gas-chromatography with coupled mass spectrometry, and by comparison with reference samples from Abies nordmanniana, which is known to produce the corresponding enantiomer. The pheromone compound was synthesized starting from (-)-α-himachalene isolated from Cedrus atlantica. Under field conditions, the activity of the synthetic pheromone required concomitant presence of the host plant volatile allyl isothiocyanate. However, both synthetic (+)-(6R,7S)-himachala-9,11-diene alone and in combination with AITC were attractive in a two-choice laboratory assay devoid of other natural olfactory stimuli. We hypothesize that P. striolata adults respond to the pheromone only if specific host volatiles are present. In the same laboratory set up, more beetles were attracted by feeding males than by the synthetic stimuli. Thus, further research will be necessary to reveal the components of a more complex blend of host or male-produced semiochemicals that might enhance trap attractiveness in the field.     

Plasmonic focusing reduces ensemble linewidth of silver-coated gold nanorods

Silver coating gold nanorods reduces the ensemble plasmon line width by changing the relation connecting particle shape and plasmon resonance wavelength. This change, we term "plasmonic focusing", leads to less variation of resonance wavelengths for the same particle size distribution. We also find smaller single particle linewidth comparing resonances at the same wavelength but show that this does not contribute to the ensemble linewidth narrowing.     

Ben van Berkel荷兰建筑大师有效组织空间的先锋

<正>UNStudio工作室创始人兼首席建筑师哈佛大学研究生院"丹下健三"荣誉讲席教授Co-Founder/Principal Architect UNStudio Kenzo Tange Chair at Harvard University Graduate School of Design     

Identification of Salicylates in Willow Bark (Salix Cortex) for Targeting Peripheral Inflammation

Salix cortex-containing medicine is used against pain conditions, fever, headaches, and inflammation, which are partly mediated via arachidonic acid-derived prostaglandins (PGs). We used an activity-guided fractionation strategy, followed by structure elucidation experiments using LC-MS/MS, CD-spectroscopy, and 1D/2D NMR techniques, to identify the compounds relevant for the inhibition of PGE₂ release from activated human peripheral blood mononuclear cells. Subsequent compound purification by means of preparative and semipreparative HPLC revealed 2′-O-acetylsalicortin (1), 3′-O-acetylsalicortin (2), 2′-O-acetylsalicin (3), 2′,6′-O-diacetylsalicortin (4), lasiandrin (5), tremulacin (6), and cinnamrutinose A (7). In contrast to 3 and 7, compounds 1, 2, 4, 5, and 6 showed inhibitory activity against PGE₂ release with different potencies. Polyphenols were not relevant for the bioactivity of the Salix extract but salicylates, which degrade to, e.g., catechol, salicylic acid, salicin, and/or 1-hydroxy-6-oxo-2-cycohexenecarboxylate. Inflammation presents an important therapeutic target for pharmacological interventions; thus, the identification of relevant key drugs in Salix could provide new prospects for the improvement and standardization of existing clinical medicine.     

Size and Shape Exclusion in 2D Silicon Dioxide Membranes

2D membranes such as artificially perforated graphene are deemed to bring great advantages for molecular separation. However, there is a lack of structure-property correlations in graphene membranes as neither the atomic configurations nor the number of introduced sub-nanometer defects are known precisely. Recently, bilayer silica has emerged as an inherent 2D membrane with an unprecedentedly high areal density of well-defined pores. Mass transfer experiments with free-standing SiO₂ bilayers demonstrated a strong preference for condensable fluids over inert species, and the measured membrane selectivity revealed a key role of intermolecular forces in ångstrom-scale openings. In this study, vapor permeation measurements are combined with quantitative adsorption experiments and density functional theory (DFT) calculations to get insights into the mechanism of surface-mediated transport in vitreous 2D silicon dioxide. The membranes are shown to exhibit molecular sieving performance when exposed to vaporous methanol, ethanol, isopropanol, and tert-butanol. The results are normalized to the coverage of physisorbed molecules and agree well with the calculated energy barriers.