Bioremediation of uranium from waste effluents using novel biosorbents: a review

Journal of Radioanalytical and Nuclear Chemistry - Several treatments for the removal of toxic heavy metals like uranium from wastewater have been developed, but none of them are sufficiently...     

Recent development in the field of ceramics solid-state electrolytes: I—oxide ceramic solid-state electrolytes

Journal of Solid State Electrochemistry - Many elements in the periodic table form ionic compounds; the crystal lattices of such compounds contain cations and anions, which are arranged in the way...     

Conformational Control of Oligo(p‐phenyleneethynylene)s with Intrinsic Substituent Electronic Effects: Origin of the Twist in Pentiptycene‐Containing Systems

Dependence of the backbone planarity of oligo(p‐phenyleneethynylene)s (OPEs) on the intrinsic electronic character of substituents and on the nature of the solvent has been experimentally demonstrated with a series of center‐symmetrical five‐ring systems, pentiptycene‐pentiptycene‐arene‐pentiptycene‐pentiptycene, differing in the substituents on the central arene. In frozen 2‐methyltetrahydrofuran (MTHF), the adjacent pentiptycene units prefer to be in a mutually twisted orientation when the substituents are electron‐withdrawing (F and amido), resulting in a TPPT or TTTT conformation, whereas a planarized PPPP backbone is favored in the case of electron‐donating substituents (alkyl and alkoxy). The propensity to adopt the PPPP form is generally enhanced by replacing MTHF with either methylcyclohexane or mixed ethanol/methanol as solvent. These observations reveal that the twist between adjacent pentiptycene units in OPEs is a consequence of the electronic rather than steric effects of iptycenyl substituents. The electronic effect of iptycenyl substituents is manifested in decreased phenylene π polarizability as the net effect of both electron‐donating hyperconjugation and an electron‐withdrawing inductive effect. Variable‐temperature electronic absorption and emission spectroscopies are the critical tools for this work. Our findings provide important guidelines for conformational and electronic engineering of OPEs and for the design of novel iptycene‐based organic electronic materials.     

Probing the Binding of Syzygium-Derived α-Glucosidase Inhibitors with N- and C-Terminal Human Maltase Glucoamylase by Docking and Molecular Dynamics Simulation

Human maltase glucoamylase (MGAM) is a potent molecular target for controlling post prandial glucose surplus in type 2 diabetes. Binding of small molecules from Syzygium sp. with α-glucosidase inhibitory potential in MGAM has been investigated in silico. Our results suggest that myricetin was the most potent inhibitor with high binding affinity for both N- and C-terminals of MGAM. Molecular dynamics revealed that myricetin interacts in its stretched conformation through water-mediated interactions with C-terminal of MGAM and by normal hydrogen bonding with the N-terminal. W1369 of the extended 21 amino acid residue helical loop of C-terminal plays a major role in myricetin binding. Owing to its additional sugar sites, overall binding of small molecules favours C-terminal MGAM.     

Effect of salicin on induction and carbon catabolite repression of endoxylanase synthesis in Penicillium janthinellum MTCC 10889

Amongst various carbon sources, xylan was found to be the sole inducer of endoxylanase production by Penicillium janthinellum MTCC 10889 in submerged cultivation. Endoxylanase synthesis by a xylan induced culture was initially repressed after a simultaneous addition of xylose, probably by the inducer exclusion mechanism, but it was resumed and achieved its highest level at a much later stage of growth (at 120 h). Xylose added after 30 h of growth cannot exert its full repressive effect. Although glucose was proved to be a more potent repressor than xylose, supplementation of salicin, an alcoholic β-glycoside containing d-glucose, with pure xylan resulted in an about 3.22 fold increase in the enzyme synthesis at 72 h followed by constant high production of the enzyme at least until the 144th h of growth. Inducing capacity of salicin in a xylan induced culture was significantly reduced when it was added after 30 h of growth. Addition of salicin and xylan help to partially overcome the repressive effect of xylose and glucose. Failure of salicin in recovering the endoxylanase synthesis in actinomycin D and cyclohexamide inhibited the xylan induced culture indicating that salicin cannot initiate the de novo synthesis of the enzyme.     

Target-Directed Azide-Alkyne Cycloaddition for Assembling HIV-1 TAR RNA Binding Ligands

The highly conserved HIV-1 transactivation response element (TAR) binds to the trans-activator protein Tat and facilitates viral replication in its latent state. The inhibition of Tat–TAR interactions by selectively targeting TAR RNA has been used as a strategy to develop potent antiviral agents. Therefore, HIV-1 TAR RNA represents a paradigmatic system for therapeutic intervention. Herein, we have employed biotin-tagged TAR RNA to assemble its own ligands from a pool of reactive azide and alkyne building blocks. To identify the binding sites and selectivity of the ligands, the in situ cycloaddition has been further performed using control nucleotide (TAR DNA and TAR RNA without bulge) templates. The hit triazole-linked thiazole peptidomimetic products have been isolated from the biotin-tagged target templates using streptavidin beads. The major triazole lead generated by the TAR RNA presumably binds in the bulge region, shows specificity for TAR RNA over TAR DNA, and inhibits Tat–TAR interactions.     

Unusual Surface Latent Heat Flux Variations and Their Critical Dynamics Revealed before Strong Earthquakes

We focus on the possible thermal channel of the well-known Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) mechanism to identify the behavior of thermal anomalies during and prior to strong seismic events. For this, we investigate the variation of Surface Latent Heat Flux (SLHF) as resulting from satellite observables. We demonstrate a spatio-temporal variation in the SLHF before and after a set of strong seismic events occurred in Kathmandu, Nepal, and Kumamoto, Japan, having magnitudes of 7.8, 7.3, and 7.0, respectively. Before the studied earthquake cases, significant enhancements in the SLHF were identified near the epicenters. Additionally, in order to check whether critical dynamics, as the signature of a complex phenomenon such as earthquake preparation, are reflected in the SLHF data, we performed a criticality analysis using the natural time analysis method. The approach to criticality was detected within one week before each mainshock.     

Electro‐optical cells using a cellulose derivative and cholesteric liquid crystals

A cellulose derivative/liquid crystal composite‐type electro‐optical cell using a commercial cholesteric liquid crystal (CLC) was investigated. The electro‐optical properties of the system were examined, i.e. the dependence on applied voltage of the reflected wavelength and the minimum and maximum transmissions. A thin film of the CLC was dispersed with a cross‐linked cellulose film of 25 µm thickness. In the voltage dependence of the reflected wavelength it was verified that there is a hysteresis in the reflected wavelength. The variation of the reflected wavelength with temperature was also determined. The results are analysed in the framework of similar systems described in the literature for CLC dispersed in a polymer matrix.