Pickering emulsion polymerization kinetics of styrene: Comparison of bare and surface modified SiO2 nanoparticles

A step towards the understanding of some mechanistic events occurring in the styrene Pickering emulsions, using a SiO₂ dispersion, is presented. Polymerizations at 80°C with different levels of a water soluble initiator were performed. The emulsion polymer content was ca. 15% with conversions close to 90%. With conversion and particle size measurements, the particle density was estimated for bare and surface modified SiO₂ particles. Then, the average number of radicals per particle was inferred, yielding a pseudo-bulk type polymerization. It was found that bare SiO₂ nanoparticles do not participate in the nucleation mechanism; however, they, along with the initiator, promote an enhanced oligomer coagulation. On the other hand, the hexadecyltrimethylammonium bromide modified SiO₂ nanoparticles do participate in the nucleation and coagulation mechanisms, yielding more stable and smaller poorly-covered polymer particles. This approach allowed untangling some events such as: particle nucleation, radical entry to particles, particle density, coagulation and vitreous and Trommsdorff effects.     

Advances on tensor network theory: symmetries,fermions, entanglement,and holography

This is a short review on selected theory developments on tensor network (TN) states for strongly correlated systems. Specifically, we briefly review the effect of symmetries in TN states, fermionic TNs, the calculation of entanglement Hamiltonians from projected entangled pair states (PEPS), and the relation between the multi-scale entanglement renormalization ansatz (MERA) and the AdS/CFT or gauge/gravity duality. We stress the role played by entanglement in the emergence of several physical properties and objects through the TN language. Some recent results along these lines are also discussed.     

k-Cosymplectic Classical Field Theories: Tulczyjew and Skinner–Rusk Formulations

The k-cosymplectic Lagrangian and Hamiltonian formalisms of first-order classical field theories are reviewed and completed. In particular, they are stated for singular and almost-regular systems. Subsequently, several alternative formulations for k-cosymplectic first-order field theories are developed: First, generalizing the construction of Tulczyjew for mechanics, we give a new interpretation of the classical field equations. Second, the Lagrangian and Hamiltonian formalisms are unified by giving an extension of the Skinner–Rusk formulation on classical mechanics.     

Highly efficient rhenium-catalyzed deoxygenation of sulfoxides without adding any reducing agent

This work reports a novel method for the deoxygenation of aromatic and aliphatic sulfoxides catalyzed by oxo-rhenium complexes without adding any reducing agent. The oxo-rhenium complex ReOCl₃(PPh₃)₂ proved to be very efficient for the deoxygenation of several sulfoxides with tolerance of different functional groups.     

A simplified second gradient model for dilatant materials: Theory and numerical implementation

This paper deals with the development of a new second gradient model, its numerical implementation and its validation. In order to remedy to the spurious mesh dependency of the post localized computation enhanced models incorporating some internal length are necessary. These models are very time consuming. In this paper we present a simplified theory within the framework of constrained micromorphic models involving only the micro volumetric strain. Provided the use of an additional penalty term in the numerical treatment, this model is quite efficient to regularize problems modelling behaviors exhibiting plastic volumetric strain such as the ones of geomaterials. More over this model is notably less time consuming than the more general ones.     

XPS and EIS studies to account for the passive behavior of the alloy Ti-6Al-4V in Hank’s solution

Journal of Solid State Electrochemistry - The passivation mechanism of the film formed on the alloy Ti-6Al-4V was evaluated in Hank’s solution to infer the properties of this alloy as an...     

Cacaoidin,First Member of the New Lanthidin RiPP Family

Lantibiotics are ribosomally synthesized and post-translationally modified peptides (RiPPs) characterized by the presence of lanthionine or methyllanthionine rings and their antimicrobial activity. Cacaoidin, a novel glycosylated lantibiotic, was isolated from a Streptomyces cacaoi strain and fully characterized by NMR, mass spectrometry, chemical derivatization approaches and genome analysis. The new molecule combines outstanding structural features, such as a high number of d -amino acids, an uncommon glycosylated tyrosine residue and an unprecedented N,N-dimethyl lanthionine. This latter feature places cacaoidin within a new RiPP family located between lanthipeptides and linaridins, here termed lanthidins. Cacaoidin displayed potent antibacterial activity against Gram-positive pathogens including Clostridium difficile. The biosynthetic gene cluster showed low homology with those of other known lanthipeptides or linaridins, suggesting a new RiPP biosynthetic pathway.     

Symplectic and nonsymplectic realizations of groups for singular systems. An example

The actions of groups for singular systems are studied in the framework of the theory of canonical transformations for presymplectic systems. Symplectic realizations as well as nonsymplectic ones arise in a natural way. As a typical example we construct the Poincaré realizations for the relativistic free massive particle.