Chemically Resolved Electrical Measurements using X-ray Photoelectron Spectroscopy

A novel approach is proposed, where energy filtered electrons, carrying both chemical identity and electrical information, serve as fine and flexible electrodes in direct electrical measurements. The method, termed 'chemically resolved electrical measurements' (CREM), is simple and general, demonstrated here with a slightly modified X-ray photoelectron spectrometer. Selected sub-surface regions are electrically analyzed and I-V curves of self-assembled monolayers, free of substrate and top contact contributions, are derived with no need for improved metallic substrates. Unique electrical information is available with this method, further supported by powerful in-situ analytical capabilities and improved top contact performance

Entangled coherent states by mixing squeezed vacuum and coherent light

Entangled coherent states are shown to emerge, with high fidelity, when mixing coherent and squeezed vacuum states of light on a beam-splitter. These maximally entangled states, where photons bunch at the exit of a beamsplitter, are measured experimentally by Fock-state projections. Entanglement is examined theoretically using a Bell-type nonlocality test and compared with ideal entangled coherent states. We experimentally show nearly perfect similarity with entangled coherent states for an optimal ratio of coherent and squeezed vacuum light. In our scheme, entangled coherent states are generated deterministically with small amplitudes, which could be beneficial, for example, in deterministic distribution of entanglement over long distances.Comment: 6 pages, 6 figures, comments are welcom

The transcription factor Krüppel homolog 1 is linked to hormone mediated social organization in bees

<p>Abstract</p> <p>Background</p> <p>Regulation of worker behavior by dominant queens or workers is a hallmark of insect societies, but the underlying molecular mechanisms and their evolutionary conservation are not well understood. Honey bee and bumble bee colonies consist of a single reproductive queen and facultatively sterile workers. The queens' influences on the workers are mediated largely via inhibition of juvenile hormone titers, which affect division of labor in honey bees and worker reproduction in bumble bees. Studies in honey bees identified a transcription factor, <it>Krüppel-homolog 1 </it>(<it>Kr-h1</it>), whose expression in worker brains is significantly downregulated in the presence of a queen or queen pheromone and higher in forager bees, making this gene an ideal candidate for examining the evolutionary conservation of socially regulated pathways in Hymenoptera.</p> <p>Results</p> <p>In contrast to honey bees, bumble bees foragers do not have higher <it>Kr-h1 </it>levels relative to nurses: in one of three colonies levels were similar in nurses and foragers, and in two colonies levels were higher in nurses. Similarly to honey bees, brain <it>Kr-h1 </it>levels were significantly downregulated in the presence versus absence of a queen. Furthermore, in small queenless groups, <it>Kr-h1 </it>levels were downregulated in subordinate workers with undeveloped ovaries relative to dominant individuals with active ovaries. Brain <it>Kr-h1 </it>levels were upregulated by juvenile hormone treatment relative to a vehicle control. Finally, phylogenetic analysis indicates that KR-H1 orthologs are presence across insect orders. Though this protein is highly conserved between honey bees and bumble bees, there are significant differences between orthologs of insects from different orders.</p> <p>Conclusions</p> <p>Our results suggest that <it>Kr-h1 </it>is associated with juvenile hormone mediated regulation of reproduction in bumble bees. The expression of this transcription factor is inhibited by the queen and associated with endocrine mediated regulation of social organization in two species of bees. Thus, KR-H1 may transcriptionally regulate a conserved genetic module that is part of a pathway that has been co-opted to function in social behavior, and adjusts the behavior of workers to their social environmental context.</p

Formation of Alkanes by Aerobic Carbon–Carbon Bond Coupling Reactions Catalyzed by a Phosphovanadomolybdic Acid

The valorization of alkanes is possible via carbon–carbon coupling reactions. A series of dialkyl cobalt complexes [(RCH_2)_2Co^(III)(bpy)_2]ClO_4 (R = H, Me, Et, and Ph) were reacted with the H_5PV_2Mo_(10)O_(40) polyoxometalate as a catalyst, leading to a selective oxidative carbon–carbon bond coupling reaction. The reaction is initiated by electron transfer from [(RCH_2)_2Co^(III)(bpy)_2]^+ to H_5PV^V_2Mo_(10)O_(40) to yield an intermediate [(RCH_2)_2Co^(IV)(bpy)_2]^(2+)–H_5PV^(IV)V^VMo_(10)O_(40), as identified by a combination of EPR and X-ray photoelectron spectroscopy experiments. The reaction is catalytic with O_2 as terminal oxidant representing an aerobic C–C bond coupling reaction