Erratum to: 2D Hexagonal SnTe monolayer: a quasi direct band gap semiconductor with strain sensitive electronic and optical properties

The European Physical Journal B - The present study investigates amplitude death in an oscillator network with asymmetric connection delays and a tree graph topology. A frequency domain analysis...     

Investigation of the catalytic activity of a Pd/biphenyl-based phosphine system in the Ullmann homocoupling of aryl bromides

We described Ullmann homocoupling promoted by a Pd/biphenyl-based phosphine system using DMF as solvent. Using Hammett equation it is found that the rate determining step of the reaction depends on the electronic nature of substituents of aryl bromides. Increase the rate of reaction with decreasing the electron donating of the substituent from NH₂ to H suggesting an oxidative addition step as the rate determining step. Decrease the rate of reaction with increasing the electron-withdrawing ability of the substituent from H to NO₂ indicating a reductive elimination step as the rate determining step.     

Epsin Mimetic UPI Peptide Delivery Strategies to Improve Endothelization of Vascular Grafts

Endothelialization of engineered vascular grafts for replacement of small-diameter coronary arteries remains a critical challenge. The ability for an acellular vascular graft to promote endothelial cell (EC) recruitment in the body would be very beneficial. This study investigated epsins as a target since they are involved in internalization of vascular endothelial growth factor receptor 2. Specifically, epsin-mimetic UPI peptides are delivered locally from vascular grafts to block epsin activity and promote endothelialization. The peptide delivery from fibrin coatings allowed for controlled loading and provided a significant improvement in EC attachment, migration, and growth in vitro. The peptides have even more important impacts after grafting into rat abdominal aortae. The peptides prevented graft thrombosis and failure that is observed with a fibrin coating alone. They also modulated the in vivo remodeling. The grafts are able to remodel without the formation of a thick fibrous capsule on the adventitia with the 100 µg mL⁻¹ peptide-loaded condition, and this condition enabled the formation of a functional EC monolayer in the graft lumen after only 1 week. Overall, this study demonstrated that the local delivery of UPI peptides is a promising strategy to improve the performance of vascular grafts.     

Collisionally assisted spectroscopy of water from 27,000 to 34,000 cm(-1)

We report here an experimental approach that enables measurement of weak transitions to a wide range of rovibrational levels of water in the energy region 27,000-34,200 cm(-1). We have previously demonstrated the use of laser double-resonance overtone excitation to access highly excited vibrational levels from single rovibrational states. Although this approach simplifies the assignment of the spectra, it strongly reduces the number of observed transitions and hence our ability to test theoretical predictions. Here, we increase significantly the number of observed transitions by allowing rotational relaxation of H2O at intermediate levels of the double-resonance excitation scheme to the levels of the same nuclear spin (ortho or para). Our recently developed semiempirical potential energy surface PES12 enables assignment of the resulting complex spectra and reproduction of the measured transitions with accuracy better than 1 cm(-1).     

A new insight on hydrogen bond donor property of bridged B–H–B protons in the interaction of diborane with some hydrogen bond acceptor molecules

Structural Chemistry - Ab initio calculations at the MP2/6-311++G(d,p) computational level were used to analyze the interactions between a molecule of B2H6 with some small molecules which often...     

Control of thiolate nucleophilicity and specificity in zinc metalloproteins by hydrogen bonding: lessons from model compound studies

A single hydrogen bond between an amide N-H and a thiolate sulfur in model complexes designed to mimic the binding site of zinc thiolate proteins, is shown to reduce the reactivity of the thiolate toward electrophiles by up to 2 orders of magnitude. In addition a single such bond is also sufficient to achieve nearly 100% regiospecificity of reaction between a strong, and hence inherently indiscriminate, alkylating agent like trimethyl oxonium tetrafluoroborate and a single sulfur in a dithiolate construct. The importance of these results in understanding how two systems such as the zinc fingers of the GATA family and the Escherichia coli DNA repair protein Ada which share the same pseudotetrahedral structure and tetrascysteinyl ligation around the zinc can fulfill such widely divergent (structural vs reactive) roles and how specificity of reaction in multithiolate-containing systems can be achieved is discussed.     

Preparation and characterization of nanostructured thin films of Au and Ag nanoparticles synthesized by ascorbic acid on modified glass surface

Immobilization of Ag and Au nanoparticles (NPs) synthesized by ascorbic acid on chemically modified glass surface has been studied. 3‐[2‐(2‐Aminoethylamino)ethylamino]propyl‐trimethoxysilane (AMPTS), N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilan, and 3‐trimethoxysilyl‐1‐propanethiol (MSPT) were used as surface modifying agents. To improve immobilization efficiency, the ammonia solution has been used along with the silane reagents, which assisted to adsorb the metal NPs on glass surface. It was found that AMPTS and MSPT have considerable effect on deposition of Ag and AuNPs on glass substrate. The fabricated thin films were characterized by using UV‐Vis spectroscopy, atomic force microscopy, energy‐dispersive X‐ray spectroscopy and subjected to antimicrobial resistance test. The UV–Vis spectra show a distinctive plasmon resonance absorbance peak for thin films of Au and AgNPs prepared with MSPT and AMPTS, respectively. Atomic force microscopy images indicate that formation of Au and AgNPs with spherical morphology after immobilization on the glass substrate and also the dimensions of NPs on the surface appear larger than those observed in the parent colloidal solution. Energy‐dispersive X‐ray spectroscopy measurements confirmed the presence of silver and gold on the modified glass surface, and elemental composition was measured. The Au and AgNPs thin films show antibacterial activity against gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacteria in comparison with a blank sample. Copyright © 2015 John Wiley & Sons, Ltd.     

Emission Turn‐On and Solubility Turn‐Off in Conjugated Polymers: One‐ and Two‐Photon‐Induced Removal of Fluorescence‐Quenching Solubilizing Groups

The synthesis of highly efficient two‐photon uncaging groups and their potential use in functional conjugated polymers for post‐polymerization modification are reported. Careful structural design of the employed nitrophenethyl caging groups allows to efficiently induce bond scission by a two‐photon process through a combination of exceptionally high two‐photon absorption cross‐sections and high reaction quantum yields. Furthermore, π‐conjugated polyfluorenes are functionalized with these photocleavable side groups and it is possible to alter their emission properties and solubility behavior by simple light irradiation. Cleavage of side groups leads to a turn‐on of the fluorescence while solubility of the π‐conjugated materials is drastically reduced.

     

Sulfur 1s near-edge x-ray absorption fine structure (NEXAFS) of thiol and thioether compounds

The speciation and quantification of sulfur species based on sulfur K-edge x-ray absorption spectroscopy is of wide interest, particularly for biological and petroleum science. These tasks require a firm understanding of the sulfur 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of relevant species. To this end, we have examined the gas phase sulfur 1s NEXAFS spectra of a group of simple thiol and thioether compounds. These high-resolution gas phase spectra are free of solid-state broadening, charging, and saturation effects common in the NEXAFS spectra of solids. These experimental data have been further analyzed with the aid of improved virtual orbital Hartree-Fock ab initio calculations. The experimental sulfur 1s NEXAFS spectra show fine features predicted by calculation, and the combination of experiment and calculation has been used to improve assignment of spectroscopic features relevant for the speciation and quantification of the sulfur compounds.