Effect of ionic liquid on polyaniline chemically synthesised under falling-pH conditions

This study investigates the effect of the ionic liquid 1-butyl-3-methyl imidazolium chloride ([bmim]Cl) on the morphological, structural, and electronic properties of polyaniline (PANI) products synthesised by the falling-pH method. Products were characterised by SEM, FT-IR, UVVIS, N₂-physisorption, and conductivity measurements. The [bmim]Cl addition strongly influenced the PANI morphology, specific surface area, porosity, and conductivity. Depending on the [bmim]Cl: ANI ratio and the synthesis pH, a wide range of PANI nanostructures could be prepared, with rod-like, and fibre-like elongated structures being the dominant morphology under most experimental conditions. Samples prepared in the presence of [bmim]Cl exhibit specific areas of ca 22–35 m² g^?1. The conductivity of the final products depends on the [bmim]Cl: ANI ratio. Temperature dependence of conductivity in the temperature range from 77 K to 300 K was also studied.     

Glass foam from window panes and bottle glass wastes

Glass foams are building materials that now compete with classic insulating polymeric and fiber materials for thermal enveloping. The low flammability, high chemical durability and thermal stability are distinct advantages over polymeric materials. The present paper proposes the possibility of producing glass foam using two types of recycled glass wastes (window panes and bottle glass) together with plaster wastes from used ceramic casting molds as foaming agent. Optical microscopy, measurements of apparent porosity and density, hydrolytic and chemical stability, as well as thermal conductivity were used in order to characterize the obtained glass foams as insulator materials for the building industry. The apparent porosity of glass foams ranges between 20.19–54.54% when using window glass wastes, and 18.77–51.75% with bottle glass wastes. Thermal conductivity was less than 0.25 W mK-1 for all the studied glasses. The obtained results confirm that there exists an alternative method for producing glass foams, for example, from glass wastes and used ceramic plaster molds, which are utilized as foaming agents with good chemical stability and insulating properties.     

Prevalence of Antimicrobial Resistant Bacteria from Conjunctival Flora in an Eye Infection Prone Breed (Saint Bernard)

The conjunctival bacterial resident and opportunistic flora of dogs may represent a major source of dissemination of pathogens throughout the environment or to other animals and humans. Nevertheless, contamination with bacteria from external sources is common. In this context, the study of the antimicrobial resistance (AMR) pattern may represent an indicator of multidrug resistant (MDR) strains exchange. The present study was focused on a single predisposed breed—Saint Bernard. The evaluated animals were healthy, but about half had a history of ocular disease/treatment. The swabs collected from conjunctival sacs were evaluated by conventional microbiological cultivation and antimicrobial susceptibility testing (AST). The most prevalent Gram-positive was Staphylococcus spp.; regardless of the history, while Gram-negative was Pseudomonas spp.; exclusively from dogs with a history of ocular disease/treatment. Other identified genera were represented by Bacillus, Streptococcus, Trueperella, Aeromonas and Neisseria. The obtained results suggest a possible association between the presence of mixed flora and a history of ocular disease/treatment. A high AMR was generally observed (90%) in all isolates, especially for kanamycin, doxycycline, chloramphenicol and penicillin. MDR was recorded in Staphylococcus spp. and Pseudomonas spp. This result together with a well-known zoonotic potential may suggest an exchange of these strains within animal human populations and the environment.     

Observation and theoretical description of periodic geometric rearrangement in electronically excited nonstoichiometric sodium-fluoride clusters

We present two-color fs pump-probe spectra of Na2F which were recorded by employing excitation wavelengths around 1208 nm (pump) and ionization wavelengths around 405 nm (probe). The observed oscillatory structure of the signal with a period of 185 fs shows an excellent agreement with our simulated spectra. The employed ab initio Wigner distribution approach provides clear evidence that this observation is caused by photoinduced metal bond breaking followed by a butterfly-type periodic geometric rearrangement.     

Quasi-Baer module hulls and applications

Let V be a module with $S=\mathrm{End}(V)$. V is called a quasi-Baer module if for each ideal J of S, $r_V(J)=eV$ for some $e^2=e\in S$. On the other hand, V is called a Rickart module if for each $?\in S$, $\mathrm{Ker}(?)=eV$ for some $e^2=e\in S$. For a module N, the quasi-Baer module hull $\mathbf{qB}(N)$ (resp., the Rickart module hull $\mathbf{Ric}(N)$) of N, if it exists, is the smallest quasi-Baer (resp., Rickart) overmodule, in a fixed injective hull $E(N)$ of N. In this paper, we initiate the study of quasi-Baer and Rickart module hulls. When a ring R is semiprime and ideal intrinsic over its center, it is shown that every finitely generated projective R-module has a quasi-Baer hull. Let R be a Dedekind domain with F its field of fractions and let $\{K_i|i\in \mathrm{\Lambda }\}$ be any set of R-submodules of $F_R$. For an R-module $M_R$ with ${\mathrm{Ann}}_R(M)\ne 0$, we show that $M_R\oplus {({?}_{i\in \mathrm{\Lambda }}{K}_i)}_R$ has a quasi-Baer module hull if and only if $M_R$ is semisimple. This quasi-Baer hull is explicitly described. An example such that $M_R\oplus {({?}_{i\in \mathrm{\Lambda }}{K}_i)}_R$ has no Rickart module hull is constructed. If N is a module over a Dedekind domain for which $N/t(N)$ is projective and ${\mathrm{Ann}}_R(t(N))\ne 0$, where $t(N)$ is the torsion submodule of N, we show that the quasi-Baer hull $\mathbf{qB}(N)$ of N exists if and only if $t(N)$ is semisimple. We prove that the Rickart module hull also exists for such modules N. Furthermore, we provide explicit constructions of $\mathbf{qB}(N)$ and $\mathbf{Ric}(N)$ and show that in this situation these two hulls coincide. Among applications, it is shown that if N is a finitely generated module over a Dedekind domain, then N is quasi-Baer if and only if N is Rickart if and only if N is Baer if and only if N is semisimple or torsion-free. For a direct sum $N_R$ of finitely generated modules, where R is a Dedekind domain, we show that N is quasi-Baer if and only if N is Rickart if and only if N is semisimple or torsion-free. Examples exhibiting differences between the notions of a Baer hull, a quasi-Baer hull, and a Rickart hull of a module are presented. Various explicit examples illustrating our results are constructed.     

Parallel distributed-memory simplex for large-scale stochastic LP problems

We present a parallelization of the revised simplex method for large extensive forms of two-stage stochastic linear programming (LP) problems. These problems have been considered too large to solve with the simplex method; instead, decomposition approaches based on Benders decomposition or, more recently, interior-point methods are generally used. However, these approaches do not provide optimal basic solutions, which allow for efficient hot-starts (e.g., in a branch-and-bound context) and can provide important sensitivity information. Our approach exploits the dual block-angular structure of these problems inside the linear algebra of the revised simplex method in a manner suitable for high-performance distributed-memory clusters or supercomputers. While this paper focuses on stochastic LPs, the work is applicable to all problems with a dual block-angular structure. Our implementation is competitive in serial with highly efficient sparsity-exploiting simplex codes and achieves significant relative speed-ups when run in parallel. Additionally, very large problems with hundreds of millions of variables have been successfully solved to optimality. This is the largest-scale parallel sparsity-exploiting revised simplex implementation that has been developed to date and the first truly distributed solver. It is built on novel analysis of the linear algebra for dual block-angular LP problems when solved by using the revised simplex method and a novel parallel scheme for applying product-form updates.