Structural and dynamical analysis of monodisperse and polydisperse colloidal systems

We present a semigrand ensemble Monte Carlo and Brownian dynamics simulation study of structural and dynamical properties of polydisperse soft spheres interacting via purely repulsive power-law potentials with a varying degree of "softness." Comparisons focus on crystal and amorphous phases at their coexistence points. It is shown through detailed structural analysis that as potential interactions soften, the "quality of crystallinity" of both monodisperse and polydisperse systems deteriorates. In general, polydisperse crystalline phases are characterized by a more ordered structure than the corresponding monodisperse ones (i.e., for the same potential softness). This counter-intuitive feature originates partly from the fact that particles of different sizes may be accommodated more flexibly in a crystal structure and from the reality that coexistence (osmotic) pressure is substantially higher for polydisperse systems. These trends diminish for softer potentials. Potential softness eventually produces substitutionally disordered crystals. However, substitutional order is apparent for the hard-spherelike interactions. Diffusionwise, crystals appear quite robust with a slight difference in the vibrational amplitudes of small and large particles. This difference, again, diminishes with potential softness. Overcrowding in amorphous polydisperse suspensions causes "delayed" diffusion at intermediate times.     

A Hot‐Segment‐Based Approach for the Design of Cross‐Amyloid Interaction Surface Mimics as Inhibitors of Amyloid Self‐Assembly

The design of inhibitors of protein–protein interactions mediating amyloid self‐assembly is a major challenge mainly due to the dynamic nature of the involved structures and interfaces. Interactions of amyloidogenic polypeptides with other proteins are important modulators of self‐assembly. Here we present a hot‐segment‐linking approach to design a series of mimics of the IAPP cross‐amyloid interaction surface with Aβ (ISMs) as nanomolar inhibitors of amyloidogenesis and cytotoxicity of Aβ, IAPP, or both polypeptides. The nature of the linker determines ISM structure and inhibitory function including both potency and target selectivity. Importantly, ISMs effectively suppress both self‐ and cross‐seeded IAPP self‐assembly. Our results provide a novel class of highly potent peptide leads for targeting protein aggregation in Alzheimer’s disease, type 2 diabetes, or both diseases and a chemical approach to inhibit amyloid self‐assembly and pathogenic interactions of other proteins as well.     

On the completeness of root vectors generated by systems of coupled hyperbolic equations

The paper is the second in a set of two papers, which are devoted to a unified approach to the problem of completeness of the generalized eigenvectors (the root vectors) for a specific class of linear non‐selfadjoint unbounded matrix differential operators. The list of the problems for which such operators are the dynamics generators includes the following: (a) initial boundary‐value problem (IBVP) for a non‐homogeneous string with both distributed and boundary damping; (b) IBVP for small vibrations of an ideal filament with a one‐parameter family of dissipative boundary conditions at one end and with a heavy load at the other end; this filament problem is treated for two cases of the boundary parameter: non‐singular and singular; (c) IBVP for a three‐dimensional damped wave equation with spherically symmetric coefficients and both distributed and boundary damping; (d) IBVP for a system of two coupled hyperbolic equations constituting a Timoshenko beam model with variable coefficients and boundary damping; (e) IBVP for a coupled Euler‐Bernoulli and Timoshenko beam model with boundary energy dissipation (the model known in engineering literature as bending‐torsion vibration model); (f) IBVP for two coupled Timoshenko beams model, which is currently accepted as an appropriate model describing vibrational behavior of a longer double‐walled carbon nanotube. Problems have been discussed in the first paper of the aforementioned set. Problems are discussed in the present paper.     

Development of Fish Immunity and the Role of β-Glucan in Immune Responses

Administration of β-glucans through various routes, including immersion, dietary inclusion, or injection, have been found to stimulate various facets of immune responses, such as resistance to infections and resistance to environmental stress. β-Glucans used as an immunomodulatory food supplement have been found beneficial in eliciting immunity in commercial aquaculture. Despite extensive research involving more than 3000 published studies, knowledge of the receptors involved in recognition of β-glucans, their downstream signaling, and overall mechanisms of action is still lacking. The aim of this review is to summarize and discuss what is currently known about of the use of β-glucans in fish.     

Sampling and digestion of waste mobile phones printed circuit boards for Cu,Pb, Ni,and Zn determination

Sampling is the most important procedure in arriving at the value of an electronic scrap. Inappropriate sampling makes other procedures, including assaying, valueless, as the sample must really represent the electronic scrap from which it was taken. The aim of this study was to develop the procedure to investigate the composition of heterogeneous printed circuit boards (PCBs) material and to show its applicability as well as its related limitations. The contents of Cu, Pb, Ni, and Zn in PCBs from wasted mobile phones were determined. Mixtures of aqua regia, hydrogen peroxide and hydrofluoric acid were applied to sample digestion. Open and closed vessel wet digestion with or without heating and microwave-assisted one was realized. For these purposes different sample amounts (0.2, 0.4, and 0.5 g) were applied and on the basis of calculated relative standard deviation values (RSD), the precision of repeated the most effective digestion was evaluated. The microwave-assisted wet digestion and mixture of aqua regia and hydrogen peroxide was found as the most effective one of the compared mixtures and applied conditions. A sample amount of 0.5 g was found as the most suitable. RSD values confirm the importance of electronic waste material sample preparation.     

Control problems for energy harvester model and interpolation in Hardy space

Three control problems for the system of two coupled differential equations governing the dynamics of an energy harvesting model are studied. The system consists of the equation of an Euler–Bernoulli beam model and the equation representing the Kirchhoff's electric circuit law. Both equations contain coupling terms representing the inverse and direct piezoelectric effects. The system is reformulated as a single evolution equation in the state space of 3-component functions. The control is introduced as a separable forcing term $\text{◂⋅▸}\mathbf{g}(x)f(t)$ on the right-hand side of the operator equation. The first control problem deals with an explicit construction of $f(t)$ that steers an initial state to zero on a time interval [0, T]. The second control problem deals with the construction of $f(t)$ such that the voltage output is equal to some given function $\mathbf{v}(t)$ (with $\mathbf{g}(x)$ being given as well). The third control problem deals with an explicit construction of both the force profile, $\mathbf{g}(x)$, and the control, $f(t)$, which generate the desired voltage output $\mathbf{v}(t)$. Interpolation theory in the Hardy space of analytic functions is used in the solution of the second and third problems.