Steady-state analysis of the Anaerobic Digestion Model No. 1 (ADM1)

The steady-state behavior of the Anaerobic Digestion Model No. 1 (ADM1) with respect to dilution rate and substrate concentration is analyzed in this study. Thereby, up to ten coexisting steady-state solutions are observed under the same operating conditions. The parameter region of a methane producing operation is limited regarding high dilution rates as well as low or high substrate concentrations. The underlying mechanisms causing those limits are investigated in detail, and the common core is identified, namely a positive feedback loop between growth of acetate degraders and acetate itself. The difference lies in the activation mechanisms of this feedback loop, which differs in the three investigated cases. The comparison of the present results with literature studies of simpler two-step models reveals qualitative differences regarding the substrate concentration. Therefore, an alternative simplified model is suggested, which shows qualitatively the same bifurcation behavior as the ADM1 considering variation of the substrate concentration.     

Finite size effect on the Raman frequency of phonons in nano-semiconductors

A comprehensive study on Raman spectroscopy with different excitation wavelengths, sample sizes, and sample shapes for optic phonons (OPs) and acoustic phonons (APs) in polar and non-polar nano-semiconductors has been performed. The study affirms that the finite size effect does not appear in the OPs of polar nano-semiconductors, while it exists in all other types of phonons. The absence of the FSE is confirmed to originate from the long-range Fr¨ohlich interaction and the breaking of translation symmetry. The result indicates that the Raman spectra of OPs cannot be used as a method to characterize the scale and crystalline property of polar nano-semiconductors.     

Numerical Investigation on the Effects of a Precursor Wetting Film on the Displacement of Two Immiscible Phases Along a Channel

A set of numerical experiments has been conducted to study the effect of a precursor fluid layer on the motion of two phase system in a channel. This system is characterized by coupled Cahn-Hillard and Navier-Stokes system together with slip boundary conditions. The solution of the governing equation involves first the solution of Cahn-Hillard equation with semi-implicit and Mixed finite element discritization with a convex splitting scheme. The Navier-Stokes equations are then solved with a P2-P0 mixed finite element method. Three cases have been investigated; in the first the effect of different wettability scenarios with no precursor layer has been investigated. In the second scenario, the effect of the precursor layer for different wettability conditions is investigated. In the third case, the effect of the thickness of the precursor layer is investigated. It is found that, wettability conditions have considerable effect on the flow of the considered two-phase system. Furthermore the existence of the precursor layer has additional influence on the breakthrough of the phases.     

Nitro-oxidized carboxycellulose nanofibers from moringa plant: effective bioadsorbent for mercury removal

Cellulose - Mercury contamination in drinking water is a worldwide problem due to its severely harming effects on the human body. A nanostructured natural bioadsorbent, carboxycellulose nanofiber...     

Potential Applications of Cucurbit[n]urils and Their Derivatives in the Capture of Hazardous Chemicals

Cucurbit[n]urils (Q[n]s) are a relatively young family of macrocycles, consisting of glycoluril units bridged by methylene groups, and their unique structures have attracted extensive attention from chemists in recent decades. Due to the presence of a rigid hydrophobic inner cavity and two polar outer portals lined with carbonyl groups, Q[n]s not only encapsulate guest species into the cavity, but also coordinate with metal ions/clusters. Considerable achievements have been obtained in the fields of Q[n]s-based host–guest chemistry, coordination chemistry, as well as the combination of host–guest and coordination chemistry. Furthermore, the outer surface of Q[n]s has been demonstrated to be capable of interacting with definite species to generate supramolecular architectures in recent years. With more in-depth research into Q[n]s, their application studies have also emerged as a hot topic. This Minireview focuses on recent advances in the potential applications of solid-state materials based on Q[n]s and their derivatives for the capture and adsorption of hazardous chemicals from a solution or a gas mixture.