Azimuthal correlations with high-pT multi-hadron cluster triggers in Au+Au collisions at ?{sNN } \sqrt {s_{NN} } = 200 GeV from STAR

Di-hadron correlation measurements have been used to probe di-jet production in heavy ion collisions at RHIC. A strong suppression of the away-side high-p _T yield in these measurements is direct evidence that high-p _T partons lose energy as they traverse the strongly interacting medium. However, since the momentum of the trigger particle is not a good measure of the jet energy, azimuthal di-hadron correlations have limited sensitivity to the shape of the fragmentation function. We explore the possibility to better constrain the initial parton energy by using clusters of multiple high-p _T hadrons in a narrow cone as the ‘trigger particle’ in the azimuthal correlation analysis. We present first results from this analysis of multi-hadron triggered correlated yields in Au+Au collisions at $ \sqrt {s_{NN} } $ \sqrt {s_{NN} } = 200 GeV from STAR. The results are compared with measurements in d + Au collisions and Pythia calculations, and the implications for energy loss and jet fragmentation are discussed.     

Degradable self-assembling dendrons for gene delivery: experimental and theoretical insights into the barriers to cellular uptake

This paper uses a combined experimental and theoretical approach to gain unique insight into gene delivery. We report the synthesis and investigation of a new family of second-generation dendrons with four triamine surface ligands capable of binding to DNA, degradable aliphatic-ester dendritic scaffolds, and hydrophobic units at their focal points. Dendron self-assembly significantly enhances DNA binding as monitored by a range of experimental methods and confirmed by multiscale modeling. Cellular uptake studies indicate that some of these dendrons are highly effective at transporting DNA into cells (ca. 10 times better than poly(ethyleneimine), PEI). However, levels of transgene expression are relatively low (ca. 10% of PEI). This indicates that these dendrons cannot navigate all of the intracellular barriers to gene delivery. The addition of chloroquine indicates that endosomal escape is not the limiting factor in this case, and it is shown, both experimentally and theoretically, that gene delivery can be correlated with the ability of the dendron assemblies to release DNA. Mass spectrometric assays demonstrate that the dendrons, as intended, do degrade under biologically relevant conditions over a period of hours. Multiscale modeling of degraded dendron structures suggests that complete dendron degradation would be required for DNA release. Importantly, in the presence of the lower pH associated with endosomes, or when bound to DNA, complete degradation of these dendrons becomes ineffective on the transfection time scale-we propose this explains the poor transfection performance of these dendrons. As such, this paper demonstrates that taking this kind of multidisciplinary approach can yield a fundamental insight into the way in which dendrons can navigate barriers to cellular uptake. Lessons learned from this work will inform future dendron design for enhanced gene delivery.     

Fabrication of oligo‐glycerol based hydrolase responsive amphiphilic nanocarriers

Herein, we report on the synthesis of a new class of novel non‐ionic amphiphiles using triglycerol as a core, which is further functionalized with hydrophilic units poly(ethylene glycol) monomethyl ether (M_n: 350 and 550) and a pair of hydrophobic alkyl chains (C₁₈ or C₁₅) via chemo‐enzymatic approach. Fluorescence measurements and dynamic light scattering studies showed that all of the synthesized amphiphilic systems spontaneously self‐ assemble in aqueous solution, which is further confirmed by the transmission electron microscopy. Encapsulation of hydrophobic moieties like Nile red and nimodipine was studied using ultraviolet‐visible (UV‐vis) and fluorescence spectrometer techniques. A cytotoxicity study of the amphiphiles using A549, HeLa, and MCF7 cell, which showed that all of the synthesized nanocarriers are well tolerated at the concentrations studied. The release profile of encapsulated Nile red in synthesized amphiphilic system was studied in the presence of the immobilized enzyme (Novozym 435).     

Adaptive Flexible Sialylated Nanogels as Highly Potent Influenza A Virus Inhibitors

Flexible multivalent 3D nanosystems that can deform and adapt onto the virus surface via specific ligand–receptor multivalent interactions can efficiently block virus adhesion onto the cell. We here report on the synthesis of a 250 nm sized flexible sialylated nanogel that adapts onto the influenza A virus (IAV) surface via multivalent binding of its sialic acid (SA) residues with hemagglutinin spike proteins on the virus surface. We could demonstrate that the high flexibility of sialylated nanogel improves IAV inhibition by 400 times as compared to a rigid sialylated nanogel in the hemagglutination inhibition assay. The flexible sialylated nanogel efficiently inhibits the influenza A/X31 (H3N2) infection with IC₅₀ values in low picomolar concentrations and also blocks the virus entry into MDCK‐II cells.     

Radical Protection by Differently Composed Creams in the UV/VIS and IR Spectral Ranges

Modern sunscreens are well suited to provide sufficient protection in the UV range because the filter substances absorb or scatter UV radiation. Although up to 50% of radicals are formed in the visible and infrared spectral range during solar radiation protection strategies are not provided in this range. Previous investigations of commercially available products have shown that in addition to physical filters, antioxidants (AO) are necessary to provide protective effects in the infrared range by neutralizing already formed radicals. In this study, the efficacy of filter substances and AO to reduce radical formation in both spectral ranges was investigated after UV/VIS or IR irradiation. Optical properties and radical protection were determined for the investigated creams. It was found that organic UV filters lower radical formation in the UV/VIS range to 35% compared to untreated skin, independent of the presence of AO. Further reduction to 14% was reached by addition of 2% physical filters, whereas physical filters alone were ineffective in the UV/VIS range due to the low concentration. In contrast, this filter type reduced radical formation in the IR range significantly to 65%; similar effects were aroused after application of AO. Sunscreens which contain organic UV filters, physical filters and AO ensure protection in the complete solar spectrum.     

Dendritic Oligoglycerol Regioisomer Mixtures and Their Utility for Membrane Protein Research

Dendrons are an important class of macromolecules that can be used for a broad range of applications. Recent studies have indicated that mixtures of oligoglycerol detergent (OGD) regioisomers are superior to individual regioisomers for protein extraction. The origin of this phenomenon remains puzzling. Here we discuss the synthesis and characterization of dendritic oligoglycerol regioisomer mixtures and their implementation into detergents. We provide experimental benchmarks to support quality control after synthesis and investigate the unusual utility of OGD regioisomer mixtures for extracting large protein quantities from biological membranes. We anticipate that our findings will enable the development of mixed detergent platforms in the future.     

Polyglycerol as a high-loading support for boronic acids with application in solution-phase Suzuki cross-couplings

In this paper, we describe the usage of a soluble high-loading polyglycerol support for functionalized boronic acids without further linker design. The quantitatively formed polyglycerol boron esters were subsequently employed in homogeneous Suzuki cross-coupling reactions to give high yields (84-91%) of functional biaryls with minimal amounts of the Pd catalyst (0.2 mol %). In situ precipitation and ultrafiltration were used as simple and effective purification protocols. Furthermore, the reaction conditions were optimized by the choice of the solvent and the catalyst.     

Overcoming Kinetic Limitations of Electron Injection in the Dye Solar Cell via Coadsorption and FRET

A new, extremely simple concept for the use of energy transfer as a means to the enhancement of light absorption and current generation in the dye solar cell (DSC) is presented. This model study is based upon a carboxy‐functionalized 4‐aminonaphthalimide dye (carboxy‐fluorol) as donor, and (NBu₄)₂[Ru(dcbpy)₂(NCS)₂] (N719) as acceptor chromophores. A set of three different devices is assembled containing either exclusively carboxy‐fluorol or N719, or a mixture of both. This set of transparent devices is characterized via IV‐measurements under AM1.5G and monochromatic illumination and their light‐harvesting and external quantum efficiencies (LHE and EQE, respectively) are determined as well. It is shown that the device containing only the donor chromophore has a marginal power conversion efficiency, thus indicating that carboxy‐fluorol is a poor sensitizer for the DSC. Cyclovoltametric measurements show that the poor sensitization ability arises from the kinetic inhibition of electron injection into the TiO₂ conduction band. Comparing the spectral properties of the DSCs assembled presently, however, demonstrates that light absorbed by carboxy‐fluorol is almost quantitatively contributing to the photocurrent if N719 is present as an additional sensitizer. In this case, N719 acts as a catalyst for the sensitization of TiO₂ by carboxy‐fluorol in addition to being a photosensitizer. Evaluation of the maximum output power under blue illumination shows that the introduction of an energy‐donor moiety via coadsorption, leads to a significant increase in the monochromatic maximum output power. This result demonstrates that energy transfer between coadsorbed chromophores could be useful for the generation of current in dye‐sensitized solar cells.     

Transition factor method for discrete master equations; and application to chemical reactions

We introduce transition factors and derive equations for them which are equivalent to the originalN-dimensional discrete master equation. After transition to continuous variables we obtain nonlocal partial differential equations for these transition factors which are slowly varying variables. Finally we consider a chemical reaction system. Using this method the corresponding master equation is exactly solvable in a very simple manner.     

Stability properties of equilibrium states

The significance of stability of an equilibrium state under local perturbations of the dynamics (as defined in [1]) and the different degree of stability with respect to extended perturbations of states at phase transition points are discussed. The general conclusions are tested and illustrated in the example of the free Bose gas. A more transparent proof of the relation between local stability and the Kubo-Martin-Schwinger relation is given.