Equilibrium and kinetic modeling of metal ion biosorption: on the ways of model generalization for the case of multicomponent systems

The paper is devoted to the problem of multicomponent sorption of metal ions on the algae-based biosorbents. The basic methods of generalization of the single-component adsorption models are reviewed or introduced and commented for both biosorption equilibrium and kinetics. The problem of similarities and difference between the competitive adsorption and the ion-exchange models is discussed and analyzed to state that both these approaches give the same results providing that only equilibrium properties are considered.     

ChemInform Abstract: Li4Ge2B as a New Derivative of the Mo2B5 and Li5Sn2 Structure Types.

Single crystals of Li₄Ge₂B are obtained by solid state reaction of stoichiometric mixtures of the elements (sealed Ta crucible, 1473 K, 15 min; rapid cooling to 25 °C).     

Scale-invariant learning and convolutional networks

Multinomial logistic regression and other classification schemes used in conjunction with convolutional networks (convnets) were designed largely before the rise of the now standard coupling with convnets, stochastic gradient descent, and backpropagation. In the specific application to supervised learning for convnets, a simple scale-invariant classification stage is more robust than multinomial logistic regression, appears to result in somewhat lower errors on several standard test sets, has similar computational costs, and features precise control over the actual rate of learning. “Scale-invariant” means that multiplying the input values by any nonzero real number leaves the output unchanged.     

Multidimensional Persistence and Noise

In this paper, we study multidimensional persistence modules (Carlsson and Zomorodian in Discrete Comput Geom 42(1):71–93, 2009; Lesnick in Found Comput Math 15(3):613–650, 2015) via what we call tame functors and noise systems. A noise system leads to a pseudometric topology on the category of tame functors. We show how this pseudometric can be used to identify persistent features of compact multidimensional persistence modules. To count such features, we introduce the feature counting invariant and prove that assigning this invariant to compact tame functors is a 1-Lipschitz operation. For one-dimensional persistence, we explain how, by choosing an appropriate noise system, the feature counting invariant identifies the same persistent features as the classical barcode construction.     

Swelling effects in cross-linked polymers by thermogravimetry

A Brazilian coal power plant generates a waste composed by the fly and bottom ashes produced from coal combustion and by a spent sulfated lime generated after SO₂ capture from combustion gases. This work presents a study of the early stages of the hydration of composites formed by this waste and a type II Portland cement, which will be used for CO₂ capture. The cement substitution degrees in the evaluated composites were 10, 20, 30 and 40%, and the effect of the coal power unit waste on the hydration reaction was analyzed on real time by NCDTA, during the first 40 h of hydration. The results show that the higher is the substitution degree, the higher is the retarding effect on the cement hydration process. Actually, by respective thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis on initial cement mass basis, this effect is caused by double exchange reactions among Ca and Mg components of the waste, during the first 4 h of hydration, which promote a much higher exothermic effect in the NCDTA curve, simultaneously to respective induction periods. The pozzolanic reactions, due to the presence of the waste silica and alumina containing amorphous phases, consume part of the original Ca(OH)₂ content existent in the waste in the case of 30 and 40% substituted pastes, and also from part of the Ca(OH)₂ produced in cement hydration reactions, in the case of the 10 and 20% substituted pastes.     

Hypergroups and Quantum Bessel Processes of Non-integer Dimensions

It is demonstrated how to use a certain family of commutative hypergroups to provide a universal construction of Biane’s quantum Bessel processes of all dimensions not smaller than 1. The classical Bessel processes \(\text {BES}(\delta )\) are analogously constructed with the aid of the Bessel–Kingman hypergroups for all, not necessarily integer, dimensions \(\delta \ge 1\).     

Driving force and activation energy in air-gap membrane distillation process

The present study investigated the impact of the driving force (Δp) on the transport properties. All the experiments and calculations were performed for air-gap membrane distillation (AGMD). In the course of the experiments, it was found that an identical value of Δp could be attained by applying different values of feed and permeate temperatures. It was highlighted that constant values of water fluxes could be achieved using the constant driving force created by different temperatures. Moreover, the relation between \({J_{{{\rm{H}}_2}{\rm{O}}}}\) and 1/T_f was shown to be linear only for the \({J_{{{\rm{H}}_2}{\rm{O}}}}\) created at ΔT = T_f ? T_p > 35 K. This work’s significant finding was to highlight the limitation of the Arrhenius-type equation applied in the activation energy calculations.