Stability of the Thin-Shell Schwarzschild-Ellis Wormhole

We investigate the stability regions of the thin-shells obtained by gluing the exterior Schwarzschild vacuum with two distinct classes of Ellis wormholes, one with zero and the other with nonzero total mass. Using the new concepts of thin-shell “mass” and of “external force” discovered recently by Garcia, Lobo and Visser, we shall apply their method to the explicit cases where some of the energy conditions in the bulk (on two sides) are violated. The stability regions are analyzed and the energetics is briefly discussed. Remarkably, we find that the stability zones are quite similar although the classes of Ellis wormholes are different. By the present examples, we confirm that the stability zones indicated by the force constraint (involving Φ and its derivatives) are more complete but restrictive than those from the mass constraint (not involving Φ).     

PLS-DA - Docking Optimized Combined Energetic Terms (PLSDA-DOCET) protocol: a brief evaluation

Docking studies have become popular approaches in drug design, where the binding energy of the ligand in the active site of the protein is estimated by a scoring function. Many promising techniques were developed to enhance the performance of scoring functions including the fusion of multiple scoring functions outcomes into a so-called consensus scoring function. Hereby, we evaluated the target oriented consensus technique using the energetic terms of several scoring functions. The approach was denoted PLSDA-DOCET. Optimization strategies for consensus energetic terms and scoring functions based on ROC metric were compared to classical rigid docking and to ligand-based similarity search methods comprising 2D fingerprints and ROCS. The ROCS results indicate large performance variations depending on the biological target. The AUC-based strategy of PLSDA-DOCET outperformed the other docking approaches regarding simple retrieval and scaffold-hopping. The superior performance of PLSDA-DOCET protocol relative to single and combined scoring functions was validated on an external test set. We found a relative low mean correlation of the ranks of the chemotypes retrieved by the PLSDA-DOCET protocol and all the other methods employed here.     

Deciphering the mystery of hexagon holes in an all-boron graphene α-sheet

Boron could be the next element after carbon capable of forming 2D-materials similar to graphene. Theoretical calculations predict that the most stable planar all-boron structure is the so-called α-sheet. The mysterious structure of the α-sheet with peculiar distribution of filled and empty hexagons is rationalized in terms of chemical bonding. We show that the hexagon holes serve as scavengers of extra electrons from the filled hexagons. This work could advance rational design of all-boron nanomaterials.     

Activators of cylindrical proteases as antimicrobials: identification and development of small molecule activators of ClpP protease

ClpP is a cylindrical serine protease whose ability to degrade proteins is regulated by the unfoldase ATP-dependent chaperones. ClpP on its own can only degrade small peptides. Here, we used ClpP as a target in a high-throughput screen for compounds, which activate the protease and allow it to degrade larger proteins, hence, abolishing the specificity arising from the ATP-dependent chaperones. Our screen resulted in five distinct compounds, which we designate as Activators of Self-Compartmentalizing Proteases 1 to 5 (ACP1 to 5). The compounds are found to stabilize the ClpP double-ring structure. The ACP1 chemical structure was considered to have drug-like characteristics and was further optimized to give analogs with bactericidal activity. Hence, the ACPs represent classes of compounds that can activate ClpP and that can be developed as potential novel antibiotics.     

pH-driven physicochemical conformational changes of single-layer graphene oxide

Single-layer graphene oxides (SLGOs) undergo morphological changes depending on the pH of the system and may account for restricted chemical reactivity. Herein, SLGO may also capture nanoparticles through layering and enveloping when the pH is changed, demonstrating potential usefulness in drug delivery or waste material capture.     

Thermally evaporated Ag nanoparticle films for plasmonic enhancement in organic solar cells: effects of particle geometry

We report on the simple fabrication of Ag NP films via thermal evaporation and subsequent annealing. The NPs are formed on indium tin oxide electrodes, coated with PEDOT:PSS and implemented into PCPDTBT:PC70BM solar cells. Scanning electron microscopy and atomic force microscopy are used to determine the size distributions and surface coverage of the NP film. We apply finite‐difference time‐domain techniques to model the optical properties of different nanoparticle films and compare this with the absorption properties of the organic active layer. The simulations demonstrate that the absorption and scattering efficiency of the particles are very sensitive to particle geometry. Solar cells prepared with window electrodes containing NP layers with less surface coverage, show a 14.8% improvement in efficiency. We discuss variations in the external quantum efficiency of the devices in terms of forward scattering and parasitic absorption losses induced by the NP layer. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

The role of interfacial chemistry and interactions in the dynamics of thermosetting polyurethane–multiwalled carbon nanotube composites at low filler contents

Acid-oxidized multiwalled carbon nanotubes (MWCNTs) were introduced into a polyurethane (PU) matrix at low filler levels (0.01–0.25 wt%) through either van der Waals or covalent interactions, and their glass transition dynamics using dynamic mechanical analysis and laser-interferometric creep rate spectroscopy was investigated. The nanocomposites reveal substantial impact on the PU glass transition dynamics, which depends on the nanotube content and type of interfacial interactions. The pronounced dynamic heterogeneity within the glass transition covering 200 °C range and the displacement of main PU relaxation maxima from around 0 to 80–140 °C were registered. The results are treated in the framework of chemical inhomogeneity, constrained dynamics effects, and different motional cooperativities. The peculiariaties of the glass transition dynamics in the composites are reflected in their dynamic and static mechanical properties, in particular a two- to threefold increase in modulus and tensile strength for the covalent interfacial interaction of MWCNTs with PU.     

Synthesis of P-Chiral [ 18 O]-Labeled Isotopomeric Oligo(deoxyribonucleoside Phosphorothioate)s and Phosphates

Diastereomerically pure, isotopically labeled 5'- O -DMT-nucleoside-3'- O -(2-thio-4,4-"spiro"-pentamethylene-1,3,2-[ 18 O]oxathiaphospholane)s and -(2-oxo-4,4-"spiro"-pentamethylene-1,3,2-[ 18 O]oxathiaphospholane)s suitable for stereocontrolled synthesis of P-chiral oligonucleotide [ 18 O]phosphorothioates and [ 18 O]phosphates were synthesized. Obtained in that way "chimeric" oligonucleotide d[A PO A PS-Rp,Sp A PS-Rp , Sp A PS-Rp C PS(18O)-Rp G PS-Rp T PS-Rp T PS-Rp,Sp T PO T] was used for determination of the stereochemistry of hydrolysis by endonuclease from Serratia marcescens .     

Development of the HPLC Method for Simultaneous Determination of Lidocaine Hydrochloride and Tribenoside Along with Their Impurities Supported by the QSRR Approach

A new liquid chromatographic (LC) method for simultaneous determination of lidocaine hydrochloride (LH) and tribenoside (TR) along with their related compounds in pharmaceutical preparations is described. Satisfactory LC separation of all analytes after the liquid–liquid extraction (LLE) procedure with ethanol was performed on a C₁₈ column using a gradient elution of a mixture of acetonitrile and 0.1 % orthophosphoric acid as the mobile phase. The procedure was validated according to the ICH guidelines. The limits of detection (LOD) and quantification (LOQ) were 4.36 and 13.21 μg mL^?1 for LH, 7.60 and 23.04 μg mL^?1 for TR, and below 0.11 and 0.33 μg mL^?1 for their impurities, respectively. Intra- and inter-day precision was below 1.97 %, whereas accuracy for all analytes ranged from 98.17 to 101.94 %. The proposed method was sensitive, robust, and specific allowing reliable simultaneous quantification of all mentioned compounds. Moreover, a comparative study of the RP-LC column classification based on the quantitative structure-retention relationships (QSRR) and column selectivity obtained in real pharmaceutical analysis was innovatively applied using factor analysis (FA). In the column performance test, the analysis of LH and TR in the presence of their impurities was carried out according to the developed method with the use of 12 RP-LC stationary phases previously tested under the QSRR conditions. The obtained results confirmed that the classes of the stationary phases selected in accordance with the QSRR models provided comparable separation for LH, TR, and their impurities. Hence, it was concluded that the proposed QSRR approach could be considered a supportive tool in the selection of the suitable column for the pharmaceutical analysis.