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Relative domain orientation of the L289K HIV-1 reverse transcriptase monomer
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Support-Mediated Reversible Redox Dynamics of Pt and Au on CeO2 at Room Temperature
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Photocatalytic Reversible Color Switching Based on Titania Nanoparticles
Abstract The photoreversible color switching system holds great promise for applications in display and signage technologies, sensing devices, and security features, because light, in comparison to other stimuli such as heat and electricity, has the advantages of noninvasiveness and easy control of parameters including wavelength, intensity, coverage area, and illumination duration. Here, the recent advances in the design and synthesis of titania nanoparticles for catalytic photoreversible color switching of redox dyes and pigments, along with their applications in ink‐free, light‐printable rewritable paper and colorimetric oxygen indicators, are reviewed. Specifically, the importance of surface engineering and defect manipulation of titania nanoparticles for the color‐switching purpose, by introducing a number of methods including surface binding of sacrificial capping ligands and creating oxygen vacancies through doping of metal ions, is highlighted. Finally, a summary and perspectives on current challenges and future research directions in this field are given.
Time-reversal breaking in QCD 4 , walls, and dualities in 2 + 1 dimensions
We study SU(N ) Quantum Chromodynamics (QCD) in 3+1 dimensions with N ƒ degenerate fundamental quarks with mass m and a θ-parameter. For generic m and θ the theory has a single gapped vacuum. However, as θ is varied through θ = π for large m there is a first order transition. For N ƒ = 1 the first order transition line ends at a point with a massless η' particle (for all N ) and for N ƒ > 1 the first order transition ends at m = 0, where, depending on the value of N ƒ , the IR theory has free Nambu-Goldstone bosons, an interacting conformal field theory, or a free gauge theory. Even when the 4 d bulk is smooth, domain walls and interfaces can have interesting phase transitions separating different 3d phases. These turn out to be the phases of the recently studied 3d Chern-Simons matter theories, thus relating the dynamics of QCD 4 and QCD 3 , and, in particular, making contact with the recently discussed dualities in 2+1 dimensions. For example, when the massless 4d theory has an SU(N ƒ ) sigma model, the domain wall theory at low (nonzero) mass supports a 3d massless CP N ƒ -1 nonlinear σ-model with a Wess-Zumino term, in agreement with the conjectured dynamics in 2+1 dimensions.
Reverse gyrase is essential for microbial growth at 95°C
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Passivity of titanium, part IV: reversible oxygen vacancy generation/annihilation
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Towards the Reverse Decomposition of Unipotents
Decomposition of unipotents gives short polynomial expressions of the conjugates of elementary generators as products of elementaries. It turns out that with some minor twist the decomposition of unipotents can be read backwards to give very short polynomial expressions of the elementary generators themselves in terms of elementary conjugates of an arbitrary matrix and its inverse. For absolute elementary subgroups of classical groups this was recently observed by Raimund Preusser. I discuss various generalizations of these results for exceptional groups, specifically those of types E{sub 6} and E{sub 7}, and also mention further possible generalizations and applications.
Reversible inhibition and reactivation of electron transfer in photosystem I
In photosystem I (PSI) complexes at room temperature light induced electron transfer can proceed down multiple protein-cofactor branches, and the process can be an order of magnitude faster on one branch compared to the other. One factor that might contribute to this branch asymmetry is a tryptophan amino acid at position 673 on the psaB protein. This amino acid is located between two of the pigments involved in electron transfer on the psaB protein branch. The corresponding residue on the psaA protein branch is a glycine amino acid. Microsecond time-resolved step-scan FTIR difference spectroscopy at 77 K has been used to study isolated PSI complexes from wild type and a mutant where the tryptophan residue was changed to phenylalanine. Photoaccumulated FTIR difference spectra indicate changes in the protein structure upon mutation. In the mutant we also find that the electron transfer processes is inhibited following long periods of repetitive flash illumination at room temperature. This is due to double protonation of the pigment involved in electron transfer. However, we show that we can restore electron transfer functionality by incubating the light-treated mutant PSI samples in the presence of newly added (not protonated) pigment.
Reversed redistribution in SPECT images from spontaneous coronary vasospasm
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A High Voltage Power Supply That Mitigates Current Reversals in Capillary Zone Electrophoresis-Electrospray Mass Spectrometry
Capillary electrophoresis coupled with electrospray ionization typically employs two power supplies, one at each end of the capillary. One power supply is located at the proximal (injection) end of the capillary. The power supply located at the distal (detector) end of the capillary drives the electrospray. Electrophoresis is driven by the difference in potential between these power supplies. Separations that employ large capillary inner diameter, high conductivity background electrolyte, and high separation potentials generate higher current than that produced by the electrospray. Excess current flows through the electrospray power supply. Most power supplies are not designed to sink current, and the excess current will cause the electrospray voltage to deviate from its set point. We report a simple circuit to handle this excess current, allowing separations under a wide range of electrophoretic conditions. .
Mass Spectral Detection of Forward- and Reverse-Hydrogen/Deuterium Exchange Resulting from Residual Solvent Vapors in Electrospray Sources
Characterizing glycans is analytically challenging since glycans are heterogeneous, branched polymers with different three-dimensional conformations. Hydrogen/deuterium exchange-mass spectrometry (HDX-MS) has been used to analyze native conformations and dynamics of biomolecules by measuring the mass increase of analytes as labile protons are replaced with deuterium following exposure to deuterated solvents. The rate of exchange is dependent on the chemical functional group, the presence of hydrogen bonds, pH, temperature, charge, and solvent accessibility. HDX-MS of carbohydrates is challenging due to the rapid exchange rate of hydroxyls. Here, we describe an observed HDX reaction associated with residual solvent vapors saturating electrospray sources. When undeuterated melezitose was infused after infusing D{sub 2}O, samples with up to 73% deuterium exchange were detected. This residual solvent HDX was observed for both carbohydrates and peptides in multiple instruments and dependent on sample infusion rate, infusion time, and deuterium content of the solvent. This residual solvent HDX was observed over several minutes of sample analysis and persisted long enough to alter the measured deuterium labeling and possibly change the interpretation of the results. This work illustrates that residual solvent HDX competes with in-solution HDX for rapidly exchanging functional groups. Thus, we propose conditions to minimize this effect, specifically for top-down, in-electrospray ionization, and quench-flow HDX experiments. .
Control of polarization reversal temperature behavior by surface screening in thin ferroelectric films
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