The 3′ end of ISY becomes covalently linked to the target DNA in the strand transfer reaction

<p><b>Copyright information:</b></p><p>Taken from " transposition of ISY, a bacterial insertion sequence belonging to the Tc/ family"</p><p></p><p>Molecular Microbiology 2007;65(6):1432-1443.</p><p>Published online Jan 2007</p><p>PMCID:PMC2170065.</p><p>© 2007 The Authors; Journal compilation © 2007 Blackwell Publishing Ltd</p> A. A pre-cleaved transposon end, 5′ end-labelled on either the top or bottom strand, was incubated with transposase and a supercoiled target plasmid. Samples were withdrawn at the indicated times and run on a non-denaturing agarose gel (TAE) or a strand-separating alkaline gel (NaOH). DNA was detected by ethidium staining, and by autoradiography (P). The positions of supercoiled (sc) and open circle (oc) target plasmid are shown to the left of the ethidium-stained gel. The positions of single end-joined (SEJ) and double end-joined (DEJ) strand transfer products are shown to the right of the autoradiographs. SEJ and DEJ products are indistinguishable on the strand separating gel. Unreacted labelled substrate has been cropped from the bottom of both autoradiographs. B. Sequence of the pre-cleaved end and schematic diagram of the reaction products

Binding of N-terminal transposase derivatives to the ISY inverted repeat

<p><b>Copyright information:</b></p><p>Taken from " transposition of ISY, a bacterial insertion sequence belonging to the Tc/ family"</p><p></p><p>Molecular Microbiology 2007;65(6):1432-1443.</p><p>Published online Jan 2007</p><p>PMCID:PMC2170065.</p><p>© 2007 The Authors; Journal compilation © 2007 Blackwell Publishing Ltd</p> A. Transposase deletion derivatives were purified by metal affinity chromatography and analysed by Coomassie-stained Tris-tricine SDS-PAGE. B. The indicated protein (1.25 μM) was incubated with IRL58, and protein–DNA complexes were separated by non-denaturing polyacrylamide gel electrophoresis. C. The indicated concentrations of Tnp and Tnp were incubated with IRL58 and complexes were separated as in (B)

Superlubric Sliding of Graphene Nanoflakes on Graphene

The lubricating properties of graphite and graphene have been intensely studied by sliding a frictional force microscope tip against them to understand the origin of the observed low friction. In contrast, the relative motion of free graphene layers remains poorly understood. Here we report a study of the sliding behavior of graphene nanoflakes (GNFs) on a graphene surface. Using scanning tunneling microscopy, we found that the GNFs show facile translational and rotational motions between commensurate initial and final states at temperatures as low as 5 K. The motion is initiated by a tip-induced transition of the flakes from a commensurate to an incommensurate registry with the underlying graphene layer (the superlubric state), followed by rapid sliding until another commensurate position is reached. Counterintuitively, the average sliding distance of the flakes is larger at 5 K than at 77 K, indicating that thermal fluctuations are likely to trigger their transitions from superlubric back to commensurate ground states

Efficient Recycling of Dilute Nitrate to Ammonia Using Cu Nanowire Electrocatalyst

Electrochemical reduction of nitrate provides a sustainable route for the recycling of waste nitrate to valuable ammonia when powered by electricity from renewable sources. Development of such a process requires efficient electrocatalysts that can facilitate high single-pass conversion of dilute nitrate to ammonia. Here we report a Cu nanowire electrocatalyst for nitrate reduction that was prepared by growing Cu nanowires with tunable morphology and density on a Cu foam substrate. Compared with the Cu foam, the Cu nanowires created new catalytic sites and greatly enhanced the activity and selectivity for nitrate reduction to ammonia. As a result, the optimized Cu nanowire electrode showed a 3-fold increase in the nitrate reduction activity with a 90% Faradaic efficiency for ammonia production at a low overpotential of −0.1 V vs RHE in an electrolyte containing 5 mM nitrate, which is attributed to the high catalytic surface area with an appropriate combination of Cu(100) and Cu(111) facets. The electrode was further tested for continuous nitrate electrolysis using a flow cell, which achieved a 76% single-pass conversion of nitrate with a 93% ammonia Faradaic efficiency, demonstrating great promise for applications in wastewater treatment and sustainable ammonia production

A Direct Grain-Boundary-Activity Correlation for CO Electroreduction on Cu Nanoparticles

Copper catalyzes the electrochemical reduction of CO to valuable C₂₊ products including ethanol, acetate, propanol, and ethylene. These reactions could be very useful for converting renewable energy into fuels and chemicals, but conventional Cu electrodes are energetically inefficient and have poor selectivity for CO vs H₂O reduction. Efforts to design improved catalysts have been impeded by the lack of experimentally validated, quantitative structure–activity relationships. Here we show that CO reduction activity is directly correlated to the density of grain boundaries (GBs) in Cu nanoparticles (NPs). We prepared electrodes of Cu NPs on carbon nanotubes (Cu/CNT) with different average GB densities quantified by transmission electron microscopy. At potentials ranging from −0.3 V to −0.5 V vs the reversible hydrogen electrode, the specific activity for CO reduction to ethanol and acetate was linearly proportional to the fraction of NP surfaces comprised of GB surface terminations. Our results provide a design principle for CO reduction to ethanol and acetate on Cu. GB-rich Cu/CNT electrodes are the first NP catalysts with significant CO reduction activity at moderate overpotential, reaching a mass activity of up to ∼1.5 A per gram of Cu and a Faradaic efficiency >70% at −0.3 V

Grain-Boundary-Dependent CO₂ Electroreduction Activity

Uncovering new structure–activity relationships for metal nanoparticle (NP) electrocatalysts is crucial for advancing many energy conversion technologies. Grain boundaries (GBs) could be used to stabilize unique active surfaces, but a quantitative correlation between GBs and catalytic activity has not been established. Here we use vapor deposition to prepare Au NPs on carbon nanotubes (Au/CNT). As deposited, the Au NPs have a relatively high density of GBs that are readily imaged by transmission electron microscopy (TEM); thermal annealing lowers the density in a controlled manner. We show that the surface-area-normalized activity for CO₂ reduction is linearly correlated with GB surface density on Au/CNT, demonstrating that GB engineering is a powerful approach to improving the catalytic activity of metal NPs

Dual-Mode Antifouling Ability of Thiol–Ene Amphiphilic Conetworks: Minimally Adhesive Coatings via the Surface Zwitterionization

A series of antibiofouling amphiphilic conetwork (APCN) coatings combined with zwitterionic features are engineered by surface zwitterionization of spontaneously segregated poly­(<i>N</i>,<i>N</i>-dimethylaminoethyl methacrylate) (PDMAEMA) segments, where this dual-mode surface integration of both passive and active modes improves the entire antifouling efficiency against the adsorption of proteins and a widespread marine fouling organism (Phaeodactylum tricornutum). A clear difference in surface morphology and topography before and after surface zwitterionization is ascribed to the transformation of PDMAEMA to carboxlbetaine zwitterion, which promotes the phase segregation and simultaneously accelerates the migration of hydrophilic segments toward the surface. The surface morphology evolved with hydrophilic content, and the variation trend of surface roughness before and after surface zwitterionization is exactly opposite under different hydrophilic content. With regard to structure–antibiofouling relationships, the zwitterionic surface with heterogeneous morphology as well as higher zwitterion content exhibits superior antibiofouling efficiency. This design provides a novel methodology for the development of heterogeneous and zwitterionic antibiofouling conetwork, which will not only act as a breakthrough for the design and synthesis of next generation of efficient and eco-friendly antibiofouling coating but also expand the synthesis method of APCN so as to explore its application fields

Ambient Electrochemical Ammonia Synthesis With High Selectivity On Fe/Fe Oxide Catalyst

Electrochemical reduction of N2 to NH3 under ambient conditions can provide an alternative to the Haber-Bosch process for distributed NH3 production that can be powered by renewable electricity. The major challenge for realizing such a process is to develop efficient electrocatalysts for the N2 reduction reaction (N2RR), as typical catalysts show a low activity and selectivity due to the barrier for N2 activation and the competing hydrogen evolution reaction (HER). Here we report an Fe/Fe3O4 catalyst for ambient electrochemical NH3 synthesis, which was prepared by oxidizing an Fe foil at 300 °C followed by in situ electrochemical reduction. The Fe/Fe3O4 catalyst exhibits a Faradaic efficiency of 8.29% for NH3 production at -0.3 V vs the reversible hydrogen electrode in phosphate buffer solution, which is around 120 times higher than that of the original Fe foil. The high selectivity is enabled by an enhancement of the intrinsic (surface-area-normalized) N2RR activity by up to 9-fold as well as an effective suppression of the HER activity. The N2RR selectivity of the Fe/Fe3O4 catalyst is also higher than that of Fe, Fe3O4, and Fe2O3 nanoparticles, suggesting Fe/Fe oxide composite to be an efficient catalyst for ambient electrochemical NH3 synthesis

Direct Aerobic Oxidative Esterification and Arylation of P(O)–OH Compounds with Alcohols and Diaryliodonium Triflates

Copper-catalyzed aerobic oxidative esterification of P­(O)–OH compounds is achieved using alcohols as efficient esterification reagents, giving the expected products with good to moderate yields. Furthermore, it is shown that the arylation of P­(O)–OH compounds proceeds efficiently to produce the corresponding products via the treatment of diaryliodonium triflates under mild reaction conditions. It is a simple way to produce a broad spectrum of functionalized phosphinates, phosphonates, and phosphates from basic starting materials with good to excellent yields. The protocol is convenient for practical application. A plausible mechanism has been proposed for the reaction

Scanning Tunneling Microscopy Study of the Structure and Interaction between Carbon Monoxide and Hydrogen on the Ru(0001) Surface

We use scanning tunneling microscopy (STM) to investigate the spatial arrangement of carbon monoxide (CO) and hydrogen (H) coadsorbed on a model catalyst surface, Ru(0001). We find that at cryogenic temperatures, CO forms small triangular islands of up to 21 molecules with hydrogen segregated outside of the islands. Furthermore, whereas for small island sizes (3–6 CO molecules) the molecules adsorb at <i>hcp</i> sites, a registry shift toward <i>top</i> sites occurs for larger islands (10–21 CO molecules). To characterize the CO structures better and to help interpret the data, we carried out density functional theory (DFT) calculations of the structure and simulations of the STM images, which reveal a delicate interplay between the repulsions of the different species