Designing Non-charging Surfaces from Non-conductive Polymers.

Polymers that prevent the generation of static charge by contact electrification can be fabricated by copolymerizing an appropriate proportion of a molecule that has the tendency to charge positively, and a molecule that has the tendency to charge negatively, against a reference material. These non-conductive polymers resist charging by contact or rubbing, and prevent the adhesion of microscopic particles.

Tilted Magnetic Levitation Enables Measurement of the Complete Range of Densities of Materials with Low Magnetic Permeability.

Magnetic levitation (MagLev) of diamagnetic or weakly paramagnetic materials suspended in a paramagnetic solution in a magnetic field gradient provides a simple method to measure the density of small samples of solids or liquids. One major limitation of this method, thus far, has been an inability to measure or manipulate materials outside of a narrow range of densities (0.8 g/cm(3) < ρ < 2.

Rectification in tunneling junctions: 2,2'-bipyridyl-terminated n-alkanethiolates.

Molecular rectification is a particularly attractive phenomenon to examine in studying structure-property relationships in charge transport across molecular junctions, since the tunneling currents across the same molecular junction are measured, with only a change in the sign of the bias, with the same electrodes, molecule(s), and contacts. This type of experiment minimizes the complexities arising from measurements of current densities at one polarity using replicate junctions. This paper describes a new organic molecular rectifier: a junction having the structure Ag(TS)/S(CH2)11-4-methyl-2,2'-bipyridyl//Ga2O3/EGaIn (Ag(TS): template-stripped silver substrate; EGaIn: eutectic gallium-indium alloy) which shows reproducible rectification with a mean r(+) = |J(+1.

Using "click-e-bricks" to make 3D elastomeric structures.

Soft, 3D elastomeric structures and composite structures are easy to fabricate using click-e-bricks, and the internal architecture of these structures together with the capabilities built into the bricks themselves provide mechanical, optical, electrical, and fluidic functions.

Catalytic asymmetric transannulation of NH-1,2,3-triazoles with olefins.

A convenient one-pot asymmetric synthesis of 2,3-dihydropyrroles from in situ generated triflated triazoles and olefins is described that further expands the utility of azavinyl carbene chemistry and provides access to an important class of cyclic enamides. Mechanistic investigations support the involvement of triflated cyclopropylaldimine intermediates in the formation of 2,3-dihydropyrrole. To the best of our knowledge, this is the first example of a chiral Brønsted acid catalyzed rearrangement of cyclopropylimines into enantioenriched 2,3-dihydropyrroles.

Mid-infrared spectrometer using opto-nanofluidic slot-waveguide for label-free on-chip chemical sensing.

A mid-infrared (mid-IR) spectrometer for label-free on-chip chemical sensing was developed using an engineered nanofluidic channel consisting of a Si-liquid-Si slot-structure. Utilizing the large refractive index contrast (Δn ∼ 2) between the liquid core of the waveguide and the Si cladding, a broadband mid-IR lightwave can be efficiently guided and confined within a nanofluidic capillary (≤100 nm wide). The optical-field enhancement, together with the direct interaction between the probe light and the analyte, increased the sensitivity for chemical detection by 50 times when compared to evanescent-wave sensing.

Transannulation of 1-sulfonyl-1,2,3-triazoles with heterocumulenes.

Readily available 1-mesyl-1,2,3-triazoles are efficiently converted into a variety of imidazolones and thiazoles by Rh(II)-catalyzed denitrogenative reactions with isocyanates and isothiocyanates, respectively. The proposed triazole-diazoimine equilibrium results in the formation of highly reactive azavinyl metal-carbenes, which react with heterocumulenes causing an apparent swap of 1,2,3-triazole core for another heterocycle.

Proprioceptive coupling within motor neurons drives C. elegans forward locomotion.

Locomotion requires coordinated motor activity throughout an animal's body. In both vertebrates and invertebrates, chains of coupled central pattern generators (CPGs) are commonly evoked to explain local rhythmic behaviors. In C.

Contact de-electrification of electrostatically charged polymers.

The contact electrification of insulating organic polymers is still incompletely understood, in part because multiple fundamental mechanisms may contribute to the movement of charge. This study describes a mechanism previously unreported in the context of contact electrification: that is, "contact de-electrification", a process in which polymers charged to the same polarity discharge on contact. Both positively charged polymeric beads, e.

Camouflage and display for soft machines.

Synthetic systems cannot easily mimic the color-changing abilities of animals such as cephalopods. Soft machines--machines fabricated from soft polymers and flexible reinforcing sheets--are rapidly increasing in functionality. This manuscript describes simple microfluidic networks that can change the color, contrast, pattern, apparent shape, luminescence, and surface temperature of soft machines for camouflage and display.

Transition-metal-free catalytic synthesis of 1,5-diaryl-1,2,3-triazoles.

1,5-Diarylsubstituted 1,2,3-triazoles are formed in high yield from aryl azides and terminal alkynes in DMSO in the presence of catalytic tetraalkylammonium hydroxide. The reaction is experimentally simple, does not require a transition-metal catalyst, and is not sensitive to atmospheric oxygen and moisture.

Rhodium-catalyzed enantioselective cyclopropanation of olefins with N-sulfonyl 1,2,3-triazoles.

N-Sulfonyl 1,2,3-triazoles readily form rhodium(II) azavinyl carbenes, which react with olefins to produce cyclopropanes with excellent diastereo- and enantioselectivity and in high yield.

REGIOSELECTIVE SYNTHESIS OF EITHER 1H- OR 2H-1,2,3- TRIAZOLES VIA MICHAEL ADDITION TO α,ß-UNSATURATED KETONES.

The Michael reaction of NH-1,2,3-triazole (1) with α,β-unsaturated ketones was studied. 1H-1,2,3-triazolyl-ketones were selectively generated when 1 was combined neat with a variety of enones. The use of aprotic solvents with catalytic base gave the corresponding 2H-regioisomers.

Facile and efficient assembly of collagen-like triple helices on a TRIS scaffold.

The TRIS scaffold, Boc-beta-Ala-TRIS-(OH)3, was utilized to assemble triple helices composed of the Gly-Nleu-Pro sequence (Nleu denotes N-isobutylglycine). The scaffold assembly can be achieved efficiently through direct coupling between long peptide chains and the TRIS scaffold using DEPBT, a recently developed peptide coupling reagent. CD spectroscopy and thermal denaturation studies demonstrated that Boc-beta-Ala-TRIS-[(Gly-Nleu-Pro)n-OMe]3 exhibits triple helicity in H2O when n equals 5, 6, and 8, while the shorter analogs (where n=1 and 4) do not.

Metal-assisted assembly and stabilization of collagen-like triple helices.

Single-chain and TRIS-assembled collagen mimetic peptide structures incorporating catechol groups were synthesized. When 1/3 equiv of Fe3+ was added to the single-chain compound in 50 mM CAPS buffer (pH 10), the 1:3 Fe3+-catechol complex that formed acted as an N-terminal scaffold to assemble the triple helix. When 1 equiv of Fe3+ was added to the TRIS-assembled compound in the buffer solution, the Fe3+-catechol complex acted as an extra C-terminal scaffold, which lead to a triple helix with both termini tethered.