Control of olefin geometry in macrocyclic ring-closing metathesis using a removable silyl group

Introducing a silyl group at one of the internal olefin positions in diolefinic substrates results in E-selective olefin formation in macrocyclic ring-forming metathesis. The application of this method to a range of macrocyclic (E)-alkenylsiloxanes is described. Protodesilylation of alkenylsiloxane products yields novel Z-configured macrocycles.     

A continuous transformation of the 3D penrose tiling

An evolution of the 3D Penrose tiling, which leads to a cubic primitive lattice on a side and to a f.c.c. vertices arrangement on the other side, is shown here. Physical implications are suggested.     

Hamilton Jacobi Isaacs equations for differential games with asymmetric information on probabilistic initial condition

We investigate Hamilton Jacobi Isaacs equations associated to a two-players zero-sum differential game with incomplete information. The first player has complete information on the initial state of the game while the second player has only information of a – possibly uncountable – probabilistic nature: he knows a probability measure on the initial state. Such differential games with finite type incomplete information can be viewed as a generalization of the famous Aumann–Maschler theory for repeated games. The main goal and novelty of the present work consists in obtaining and investigating a Hamilton Jacobi Isaacs Equation satisfied by the upper and the lower values of the game. Since we obtain a uniqueness result for such Hamilton Jacobi equation, as a byproduct, this gives an alternative proof of the existence of a value of the differential game (which has been already obtained in the literature by different technics). Since the Hamilton Jacobi equation is naturally stated in the space of probability measures, we use the Wasserstein distance and some tools of optimal transport theory.     

Uniaxial and Coaxial Electrospinning for Tailoring Jussara Pulp Nanofibers

Jussara pulp (Euterpe edulis Mart.) is rich in bioactive compounds known to be protective mediators against several diseases. In this context, nevertheless, anthocyanins, the most abundant natural pigment in jussara, are sensitive to temperature, pH, oxygen, and light conditions, leading to instability during food storage or digestion, and, thus jeopardizing the antioxidant proprieties retained by these flavonoids and limiting industrial application of the pulp. The production of nanostructures, from synthetic and natural polymers, containing natural matrices rich in bioactive compounds, has been widely studied, providing satisfactory results in the conservation and maintenance of the stability of these compounds. The current work aimed to compare uniaxial and coaxial electrospinning operation modes to produce core-shell jussara pulp nanofibers (NFs). Additionally, the parameters employed in the electrospinning processes were optimize using response surface methodology in an attempt to solve stability issues for the bioactive compounds. The best experimental conditions provided NFs with diameters ranging between 110.0 ± 47 and 121.1 ± 54 nm. Moreover, the coaxial setup improved jussara pulp NF formation, while further allowing greater integrity of NFs structures.     

$$\Lambda _b \rightarrow \pi ^- (D_s^-) \Lambda _c(2595),~\pi ^- (D_s^-) \Lambda _c(2625)$$ decays and $$DN,~D^*N$$DN,D∗N molecular components

From the perspective that \(\Lambda _c(2595)\) and \(\Lambda _c(2625)\) are dynamically generated resonances from the \(DN,~D^*N\) interaction and coupled channels, we have evaluated the rates for \(\Lambda _b \rightarrow \pi ^- \Lambda _c(2595)\) and \(\Lambda _b \rightarrow \pi ^- \Lambda _c(2625)\) up to a global unknown factor that allows us to calculate the ratio of rates and compare with experiment, where good agreement is found. Similarly, we can also make predictions for the ratio of rates of the, yet unknown, decays of \(\Lambda _b \rightarrow D_s^- \Lambda _c(2595)\) and \(\Lambda _b \rightarrow D_s^- \Lambda _c(2625)\) and make estimates for their individual branching fractions.     

Polyethylene Nanocomposite Heat‐Sealants with a Versatile Peelable Character

A novel heat‐sealing performance is achieved by polyethylene (PE) nanocomposites reinforced by ethylene vinyl acetate (EVA) and montmorillonite (MMT). Appropriate nanocomposite design leads to hermetic seals with a general peelable/easy‐open character across the broadest possible sealing temperature range. Observations of the fracture seal surfaces by infrared spectroscopy and electron microscopy reveal that this behavior originates from a synergistic effect of the EVA copolymer and the montmorillonite clay nanofiller. Namely, the combination of EVA‐copolymers and MMT nanofillers provides sufficiently favorable interactions for nanocomposite formation and mechanical robustness, but weak enough interfacial adhesion to promote a general cohesive failure of the sealant at the EVA/MMT interfaces.

     

Al versus Si competition in FeSiAl alloys

In FeSiAl alloys, when Si substitutes for Al, important changes take place in the magnetism as well as in the structural properties. Alloys in the two composition series Fe₇₅Al_25−xSi_x (x=0, 7.5, 12.5, 17.5, 25) and Fe₇₀Al_30−xSi_x (x=0, 9, 15, 21, 30) were prepared by induction melting; afterwards they were crushed and then annealed in order to recover the DO₃ stable phase. The deformed FeAl samples show larger lattice parameters than the ordered ones; however, this difference (Δa) decreases when Si substitutes for Al until it becomes zero (i.e. until the ordered samples and the deformed ones have the same lattice parameters). This trend is the same for both sample series and does not depend on the Fe content of the alloy. However, the magnetization has a different behaviour depending on the Fe content. For deformed Fe₇₅Al_25−xSi_x alloys the saturation magnetization decreases with increasing Si content while for Fe₇₀Al_30−xSi_x deformed alloys the saturation magnetization has a plateau in which the saturation magnetization values do not vary.     

A reactivity study of addition of organic halides to CpMo(CO)3−: counterion and RX dependences

Rates of reaction of CpMo(CO)₃^? with organic halides to yield CpMo(CO)₃R showed opposite counterion effects according to the type of RX reagent.