Functionalization of Pyridines at the C4 Position via Metalation and Capture.

The functionalization of pyridines at positions remote to the N-atom remains an outstanding problem in organic synthesis. The inherent challenges associated with overriding the influence of the embedded N-atom within pyridines was overcome using n-butylsodium, which provided an avenue to deprotonate and functionalize the C4-position over traditionally observed addition products that are formed with organolithium bases. In this work, we show that freshly generated 4-sodiopyrdines could undergo transition metal free alkylation reactions directly with a variety of primary alkyl halides bearing diverse functional groups.

Design and Synthesis of Dialkylarylphosphine Urea Ligands and their Application in Palladium-Catalyzed Cross-Coupling Reactions.

We describe herein the design and synthesis of a new class of dialkylarylphosphine ligands incorporating a Lewis-basic urea subunit. The ligand synthesis consisted of six linear steps and was enabled by the discovery of a new N-to-N alkyl migration reaction. This new series of dialkylarylphosphine urea ligands were applied in common palladium-catalyzed cross-coupling reactions for the formation of carbon-carbon and carbon-nitrogen bonds in moderate to high yields.

Anisotropic magnetoresistance in altermagnetic MnTe.

Recently, MnTe was established as an altermagnetic material that hosts spin-polarized electronic bands as well as anomalous transport effects like the anomalous Hall effect. In addition to these effects arising from altermagnetism, MnTe also hosts other magnetoresistance effects. Here, we study the manipulation of the magnetic order by an applied magnetic field and its impact on the electrical resistivity.

Observation of a spontaneous anomalous Hall response in the MnSi d-wave altermagnet candidate.

Phases with spontaneous time-reversal ( ) symmetry breaking are sought after for their anomalous physical properties, low-dissipation electronic and spin responses, and information-technology applications. Recently predicted altermagnetic phase features an unconventional and attractive combination of a strong -symmetry breaking in the electronic structure and a zero or only weak-relativistic magnetization. In this work, we experimentally observe the anomalous Hall effect, a prominent representative of the -symmetry breaking responses, in the absence of an external magnetic field in epitaxial thin-film MnSi with a vanishingly small net magnetic moment.

Cyclopropenimine-Mediated CO Activation for the Synthesis of Polyurethanes and Small-Molecule Carbonates and Carbamates.

Carbon dioxide (CO) is an abundant C1 feedstock with tremendous potential to produce versatile building blocks in synthetic applications. Given the adverse impact of CO on the atmosphere, it is of paramount importance to devise strategies for upcycling it into useful materials, such as polymers and fine chemicals. To activate such stable molecule, superbases offer viable modes of binding to CO.

Effect of Solvent on the Rate of Ozonolysis: Development of a Homogeneous Flow Ozonolysis Protocol.

Herein, we describe the effect of organic solvents on ozone solubility and the rate of ozonolysis reactions using rapid injection NMR spectroscopy. The tabulated solubility and kinetic data allowed for the design of a homogeneous ozonolysis flow reactor capable of delivering precise quantities of dissolved ozone to various olefin substrates.

Probing magnetic properties at the nanoscale: in-situ Hall measurements in a TEM.

We report on advanced in-situ magneto-transport measurements in a transmission electron microscope. The approach allows for concurrent magnetic imaging and high resolution structural and chemical characterization of the same sample. Proof-of-principle in-situ Hall measurements on presumably undemanding nickel thin films supported by micromagnetic simulations reveal that in samples with non-trivial structures and/or compositions, detailed knowledge of the latter is indispensable for a thorough understanding and reliable interpretation of the magneto-transport data.

Capturing primary ozonides for a syn-dihydroxylation of olefins.

Ozonolysis is a widely used and practical synthetic technique for the deconstructive oxidation of olefins using ozone. While there are numerous ozonolysis reactions that give a myriad of products and functionalities, almost all of them involve scission at the olefin double bond. Using ozone as a constructive reagent rather than a deconstructive one would open new domains of chemical reactivity and amplify molecular complexity in synthetic methodology.

Breaking the -Butyllithium Contact Ion Pair: A Gateway to Alternate Selectivity in Lithiation Reactions.

The effects of Lewis basic phosphoramides on the aggregate structure of BuLi have been investigated in detail by NMR and DFT methods. It was determined that hexamethylphosphoramide (HMPA) can shift the equilibrium of BuLi to include the triple ion pair (-Bu-Li--Bu)/HMPALi which serves as a reservoir for the highly reactive separated ion pair -Bu/HMPALi. Because the Li-atom's valences are saturated in this ion pair, the Lewis acidity is significantly decreased; in turn, the basicity is maximized which allowed for the typical directing effects within oxygen heterocycles to be overridden and for remote sp C-H bonds to be deprotonated.

Preparation of Highly Reactive Lithium Metal Dendrites for the Synthesis of Organolithium Reagents.

A long-standing problem in the area of organolithium chemistry has been the need for a highly reactive Li-metal source that mimics Li-powders but has the advantage of being freshly prepared from inexpensive and readily available Li-sources. Here, we report a simple and convenient activation method using liquid ammonia that furnishes a new Li-metal source in the form of crystalline Li-dendrites. The Li-dendrites were shown to have ca.

Signatures of the Magnetic Entropy in the Thermopower Signals in Nanoribbons of the Magnetic Weyl Semimetal CoSnS.

Weyl semimetals exhibit interesting electronic properties due to their topological band structure. In particular, large anomalous Hall and anomalous Nernst signals are often reported, which allow for a detailed and quantitative study of subtle features. We pattern single crystals of the magnetic Weyl semimetal CoSnS into nanoribbon devices using focused ion beam cutting and optical lithography.

A Dinuclear Mechanism Implicated in Controlled Carbene Polymerization.

Carbene polymerization provides polyolefins that cannot be readily prepared from olefin monomers; however, controlled and living carbene polymerization has been a long-standing challenge. Here we report a new class of initiators, (π-allyl)palladium carboxylate dimers, which polymerize ethyl diazoacetate, a carbene precursor in a controlled and quasi-living manner, with nearly quantitative yields, degrees of polymerization >100, molecular weight dispersities 1.2-1.

All Electrical Access to Topological Transport Features in MnPtSn Films.

The presence of nontrivial magnetic topology can give rise to nonvanishing scalar spin chirality and consequently a topological Hall or Nernst effect. In turn, topological transport signals can serve as indicators for topological spin structures. This is particularly important in thin films or nanopatterned materials where the spin structure is not readily accessible.

Does Sodium Citrate Cause the Same Ergogenic Effect As Sodium Bicarbonate on Swimming Performance?

The aim of this study was to investigate the effect of ingesting sodium bicarbonate (SB) and sodium citrate (SC) on 400 m high-intensity swimming performance and blood responses. Six nationally ranked male swimmers (20.7 ± 2.

Mechanistically Guided Design of Ligands That Significantly Improve the Efficiency of CuH-Catalyzed Hydroamination Reactions.

Using a mechanically guided ligand design approach, a new ligand (SEGFAST) for the CuH-catalyzed hydroamination reaction of unactivated terminal olefins has been developed, providing a 62-fold rate increase over reactions compared to DTBM-SEGPHOS, the previous optimal ligand. Combining the respective strengths of computational chemistry and experimental kinetic measurements, we were able to quickly identify potential modifications that lead to more effective ligands, thus avoiding synthesizing and testing a large library of ligands. By optimizing the combination of attractive, noncovalent ligand-substrate interactions and the stability of the catalyst under the reaction conditions, we were able to identify a finely tuned hybrid ligand that greatly enables accelerated hydrocupration rates with unactivated alkenes.

Two-Step Magnetization Reversal FORC Fingerprint of Coupled Bi-Segmented Ni/Co Magnetic Nanowire Arrays.

First Order Reversal Curve (FORC) analysis has been established as an appropriate method to investigate the magnetic interactions among complex ferromagnetic nanostructures. In this work, the magnetization reversal mechanism of bi-segmented nanowires composed by long Co and Ni segments contacted at one side was investigated, as a model system to identify and understand the FORC fingerprint of a two-step magnetization reversal process. The resulting hysteresis loop of the bi-segmented nanowire array exhibits a completely different magnetic behavior than the one expected for the magnetization reversal process corresponding to each respective Co and Ni nanowire arrays, individually.

Elucidating the Role of the Boronic Esters in the Suzuki-Miyaura Reaction: Structural, Kinetic, and Computational Investigations.

The Suzuki-Miyaura reaction is the most practiced palladium-catalyzed, cross-coupling reaction because of its broad applicability, low toxicity of the metal (B), and the wide variety of commercially available boron substrates. A wide variety of boronic acids and esters, each with different properties, have been developed for this process. Despite the popularity of the Suzuki-Miyaura reaction, the precise manner in which the organic fragment is transferred from boron to palladium has remained elusive for these reagents.

Technical feasibility study for production of tailored multielectrode arrays and patterning of arranged neuronal networks.

In this manuscript, we first reveal a simple ultra violet laser lithographic method to design and produce plain tailored multielectrode arrays. Secondly, we use the same lithographic setup for surface patterning to enable controlled attachment of primary neuronal cells and help neurite guidance. For multielectrode array production, we used flat borosilicate glass directly structured with the laser lithography system.

Large magneto-Seebeck effect in magnetic tunnel junctions with half-metallic Heusler electrodes.

Spin caloritronics studies the interplay between charge-, heat- and spin-currents, which are initiated by temperature gradients in magnetic nanostructures. A plethora of new phenomena has been discovered that promises, e.g.

A study of the beam-specific interplay effect in proton pencil beam scanning delivery in lung cancer.

Background: For lung tumors with large motion amplitudes, the use of proton pencil beam scanning (PBS) can produce large dose errors. In this study, we assess under what circumstances PBS can be used to treat lung cancer patients who exhibit large tumor motion, based on the quantification of tumor motion and the dose interplay.

Material And Methods: PBS plans were optimized on average 4DCT datasets using a beam-specific PTV method for 10 consecutive patients with locally advanced non-small-cell-lung-cancer (NSCLC) treated with proton therapy to 6660/180 cGy.

Structural, Kinetic, and Computational Characterization of the Elusive Arylpalladium(II)boronate Complexes in the Suzuki-Miyaura Reaction.

The existence of the oft-invoked intermediates containing the crucial Pd-O-B subunit, the "missing link", has been established in the Suzuki-Miyaura cross-coupling reaction. The use of low-temperature, rapid injection NMR spectroscopy (RI-NMR), kinetic studies, and computational analysis has enabled the generation, observation, and characterization of these highly elusive species. The ability to confirm the intermediacy of Pd-O-B-containing species provided the opportunity to clarify mechanistic aspects of the transfer of the organic moiety from boron to palladium in the key transmetalation step.

Pre-transmetalation intermediates in the Suzuki-Miyaura reaction revealed: The missing link.

Despite the widespread application of Suzuki-Miyaura cross-coupling to forge carbon-carbon bonds, the structure of the reactive intermediates underlying the key transmetalation step from the boron reagent to the palladium catalyst remains uncertain. Here we report the use of low-temperature rapid injection nuclear magnetic resonance spectroscopy and kinetic studies to generate, observe, and characterize these previously elusive complexes. Specifically, this work establishes the identity of three different species containing palladium-oxygen-boron linkages, a tricoordinate boronic acid complex, and two tetracoordinate boronate complexes with 2:1 and 1:1 stoichiometry with respect to palladium.

Case Study: Competition Nutrition Intakes During the Open Water Swimming Grand Prix Races in Elite Female Swimmer.

The nutritional intake of elite open water swimmers during competition is not well established, and therefore this case study aims to provide new insights by describing the feeding strategies adopted by an elite female swimmer (28 yrs; height; 1.71 m; body mass: 60 kg; body fat: 16.0%) in the FINA open water Grand Prix 2014.

Tunnel junction based memristors as artificial synapses.

We prepared magnesia, tantalum oxide, and barium titanate based tunnel junction structures and investigated their memristive properties. The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use. Here, we increased the amplitude of the resistance change from 10% up to 100%.

On/off switching of bit readout in bias-enhanced tunnel magneto-Seebeck effect.

Thermoelectric effects in magnetic tunnel junctions are promising to serve as the basis for logic devices or memories in a "green" information technology. However, up to now the readout contrast achieved with Seebeck effects was magnitudes smaller compared to the well-established tunnel magnetoresistance effect. Here, we resolve this problem by demonstrating that the tunnel magneto-Seebeck effect (TMS) in CoFeB/MgO/CoFeB tunnel junctions can be switched on to a logic "1" state and off to "0" by simply changing the magnetic state of the CoFeB electrodes.