G-Quadruplex Recognition by DARPIns through Epitope/Paratope Analogy**

We investigated the mechanisms leading to the specific recognition of Guanine Guadruplex (G4) by DARPins peptides, which can lead to the design of G4 s specific sensors. To this end we carried out all-atom molecular dynamic simulations to unravel the interactions between specific nucleic acids, including human-telomeric (h-telo), Bcl-2, and c-Myc, with different peptides, forming a DARPin/G4 complex. By comparing the sequences of DARPin with that of a peptide known for its high affinity for c-Myc, we show that the recognition cannot be ascribed to sequence similarity but, instead, depends on the complementarity between the three-dimensional arrangement of the molecular fragments involved: the α-helix/loops domain of DARPin and the G4 backbone. Our results reveal that DARPins tertiary structure presents a charged hollow region in which G4 can be hosted, thus the more complementary the structural shapes, the more stable the interaction.     

An In Vitro Pilot Fermentation Study on the Impact of Chlorella pyrenoidosa on Gut Microbiome Composition and Metabolites in Healthy and Coeliac Subjects

The response of a coeliac and a healthy gut microbiota to the green algae Chlorella pyrenoidosa was evaluated using an in vitro continuous, pH controlled, gut model system, which simulated the human colon. The effect of C. pyrenoidosa on the microbial structure was determined by 16S rRNA gene sequencing and inferred metagenomics, whereas the metabolic activitywas determined by¹H-nuclear magnetic resonancespectroscopic analysis. The addition of C. pyrenoidosa significantly increased the abundance of the genera Prevotella, Ruminococcus and Faecalibacterium in the healthy donor, while an increase in Faecalibacterium, Bifidobacterium and Megasphaera and a decrease in Enterobacteriaceae were observed in the coeliac donor. C. pyrenoidosa also altered several microbial pathways including those involved in short-chain fatty acid (SCFA) production. At the metabolic level, a significant increase from baseline was seen in butyrate and propionate (p < 0.0001) in the healthy donor, especially in vessels 2 and 3. While acetate was significantly higher in the healthy donor at baseline in vessel 3 (p < 0.001) compared to the coeliac donor, this was markedly decreased after in vitro fermentation with C. pyrenoidosa. This is the first in vitro fermentation study of C. pyrenoidosa and human gut microbiota, however, further in vivo studies are needed to prove its efficacy.     

Chemical promenades: Exploring potential-energy surfaces with immersive virtual reality

The virtual-reality framework AVATAR (Advanced Virtual Approach to Topological Analysis of Reactivity) for the immersive exploration of potential-energy landscapes is presented. AVATAR is based on modern consumer-grade virtual-reality technology and builds on two key concepts: (a) the reduction of the dimensionality of the potential-energy surface to two process-tailored, physically meaningful generalized coordinates, and (b) the analogy between the evolution of a chemical process and a pathway through valleys (potential wells) and mountain passes (saddle points) of the associated potential energy landscape. Examples including the discovery of competitive reaction paths in simple A + BC collisional systems and the interconversion between conformers in ring-puckering motions of flexible rings highlight the innovation potential that augmented and virtual reality convey for teaching, training, and supporting research in chemistry.     

Study of Glow Wire Ignition Temperature (GWIT) and Comparative Tracking Index (CTI) performances of engineering thermoplastics and correlation with material properties

Recent regulation IEC 60335-1 ed.4 (2008) was introduced for materials used in electric appliance, establishing new limits in Glow Wire Ignition Temperature (GWIT) performance for materials used for electric connectors. Development of new products with high GWIT is possible, but the main issue is to keep good mechanical properties and processability, as well as tracking resistance (Comparative Tracking Index-CTI). Only a few patents and scientific publications exist about glow wire test performance of polymers. In this work we report GWIT and CTI properties for three engineering thermoplastic polymers (PBT, PET and PC). We have also studied the phenomena involved in this test, treating the phenomena with the parameterisation approach already used in the studies of the fire behaviour of polymers. PC, PBT and PET filled with 30% w/w glass fibres have been tested, and material properties that can be related to GWIT and CTI performance have been measured by TGA, Laser Flash Thermal Diffusivity (LFTD), Pyrolysis-GC/MS. CTI seems to be correlated with the char formation tendency of the materials, so PBT show a higher tracking resistance than PET and PC. Polycarbonate was the only material that passed the glow wire test (GWIT higher than 775 °C) but generally GWIT performance is not directly related with degradation temperature, since PET is thermally more stable compared with PBT, but less stable in glow wire test. The ignition process, together with the unsteady heat and mass transfer process characteristic of glow wire testing, are affected by many parameters at the same time. That’s why it is not easy to relate results of TGA, Laser flash, Pyrolysis-GC/MS with the glow wire ignition temperature of the materials tested, but the whole of these properties can give useful indication.     

Search for new heavy particles in the WZ0 final state in pp collisions at square root[s] = 1.8 TeV

We present the first general search for new heavy particles, X, which decay via X --> WZ0 --> e(nu)+jj as a function of M(X) and Gamma(X) in pp collisions at square root[s] = 1.8 TeV. No evidence is found for production of X in 110 pb(-1) of data collected by the Collider Detector at Fermilab. General cross section limits are set at the 95% C.L. as a function of mass and width of the new particle. The results are further interpreted as mass limits on the production of new heavy charged vector bosons which decay via W' --> WZ0 in an extended gauge model as a function of the width, Gamma(W'), and mixing factor between the W' and the standard model W bosons.     

Intrinsic d-wave effects in YBa(2)Cu(3)O(7-delta) grain boundary Josephson junctions

We have measured the angular dependence of the Josephson critical current density (J(C)) in c-axis tilt biepitaxial grain boundary YBa(2)Cu(3)O(7-delta) junctions. We observe for the first time intrinsic d-wave pairing symmetry effects manifested as an oscillatory dependence of J(C) on angle. This intrinsic effect is evident even though spontaneous currents, possibly induced by faceting or barrier impurities, are observed in the grain boundaries.     

Analysis of models for the ziegler-natta stereospecific polymerization on the basis of non-bonded interactions at the catalytic site—II: Edges,steps and reliefs on the surface of layered modifications of TiCl3

The computations performed in a previous paper for hypothetical structures of the site active in the polymerization of olefins at the (110) surfaces of TiCl₃-α are extended to edges, steps and reliefs on (111) surfaces of all the layered modifications of TiCl₃. Our computations suggest that edges, steps and reliefs of all the layered modifications of TiCl₃ should behave similarly in providing active sites; polymerization should occur on these more exposed sites because of the much lower activation energies than for plain surfaces. A unique general model emerges: lower steric repulsions appear to be implied for a coordination of the polymeric chain on the more hindered octahedral position at a titanium atom and this, in turn, causes a chiral orientation of the first carbon-carbon bond of the chain. This orientation may be the main factor in determining the stereospecificity.