Diversity-oriented synthesis of 13- to 18-membered macrolactams via ring-closing metathesis

An efficient build/couple/pair approach to diversity-oriented synthesis was employed to access several structurally complex macrolactams. In this paper, we describe the successful evaluation of ring-closing metathesis toward the systematic generation of skeletal diversity. By appropriately varying the nature and chain length of the alkenol fragment, a diverse collection of 13- to 18-membered macrolactams were obtained.     

Dispersion stability of nanoparticles in ecotoxicological investigations: the need for adequate measurement tools

One of the main challenges in nanoecotoxicological investigations is in the selection of the most suitable measurement methods and protocols for nanoparticle characterisation. Several parameters have been identified as being important as they govern nanotoxicological activity, with some parameters being better defined than others. For example, as a parameter, there is some ambiguity as to how to measure dispersion stability in the context of ecotoxicological investigations; indeed, there is disagreement over which are the best methods to measure nanoparticle dispersion stability. The purpose of this article is to use various commercially available tools to measure dispersion stability and to understand the information given by each tool. In this study, CeO₂ was dispersed in two different types of media: de-ionised water and electrolyte-containing fish medium. The DLS mean particle size of freshly dispersed sample in DI water was ~200 nm in diameter. A visual sedimentation experiment showed that nanoparticle dispersion made in the fish medium was less stable compared to corresponding dispersion in de-ionised water. Stability of these dispersions was monitored using various techniques, for a period of 3 days. Our findings have shown that dispersion stability can be suitably assessed by monitoring: (a) surface charge, (b) sedimentation events and (c) presence of agglomerates, through time. The majority of techniques employed here (zeta potential, particle size via DLS, fluorescence and UV–Vis spectroscopy and SEM) were shown to provide useful, complementary information on dispersion stability. Nanoparticle Tracking Analysis (NTA) provides useful, quantitative information on the concentration of nanoparticles in suspension, but is limited by its inability to accurately track the motion of large agglomerates found in the fish medium.     

An application of the Gyárfás path argument

We adapt the Gyárfás path argument to prove that $t?2$ cops can capture a robber, in at most $t?1$ moves, in the game of Cops and Robbers played in a graph that does not contain the $t$-vertex path as an induced subgraph.     

Crystal growth,structure and characterization of diglycine zinc dipicrate: Centrosymmetric crystal exhibiting second harmonic generation efficiency

A new cadmium coordination polymer, formulated as [Cd(L)(phen)]_n, were prepared by hydrothermal reactions based on 3,4-dibromothiophene-2,5-dicarboxylic acid (H₂L) and 1,10-phenanthroline (phen) mixed organic linkers. In the complex, adjacent Cd²⁺ ions are linked by L^2? anions to form a one-dimensional (1D) [CdL]_n chain with [Cd₂(COO)₂] as the secondary building unit (SBU). These adjacent chains are further stacked together by direct C?Br···Br halogen bonds interactions, generating a two-dimensional (2D) supramolecular structure. From the viewpoint of topology, the 2D supramolecular network can be rationalized to a 3,4-connected 3,4L13 net with {4.6²}₂{4².6².8²} topology.     

Analysis of the nonlinear vibration of a two-mass–spring system with linear and nonlinear stiffness

An analytical approach is developed for areas of nonlinear science such as the nonlinear free vibration of a conservative, two-degree-of-freedom mass–spring system having linear and nonlinear stiffnesses. The main contribution of this research is twofold. First, it introduces the transformation of two nonlinear differential equations for a two-mass system using suitable intermediate variables into a single nonlinear differential equation and, more significantly, the treatment of a nonlinear differential system by linearization coupled with Newton’s method. Secondly, the major section is the solving of the governing nonlinear differential equation where the displacement of the two-mass system can be obtained directly from the linear second-order differential equation using a first-order variational approach. The aforementioned approach proposed by J.H. He, who actually developed the method, is exactly He’s variational method. This approach is an explicit method with high validity for resolving strong nonlinear oscillation system problems. Two examples of nonlinear two-degree-of-freedom mass–spring systems are analyzed, and verified with published results and exact solutions. The method can be easily extended to other nonlinear oscillations and so could be widely applicable in engineering and science.     

Comparison of closed-loop and open-loop feedback schemes of message decoding using chaotic laser diodes

An experimental study of a chaotic optical communication scheme using an external cavity laser diode to encode a message is reported. The message is decoded in closed- and open-loop receiver schemes. Both schemes show effective decoding of a 1-GHz message. The synchronization and effectiveness of encoding are compared in both schemes.     

Efficient Transformation of Furfuryl Alcohol Into Ethyl Levulinates via Alcoholysis Reaction Catalyzed by SnO2/H-Mordenite Catalyst

Catalysis Surveys from Asia - Catalytic production of ethyl levulinate by alcoholysis of furfuryl alcohol with ethanol was investigated over H-mordenite supported Sn catalyst under atmospheric N2...     

Aminoquinoline based highly sensitive fluorescent sensor for lead(II) and aluminum(III) and its application in live cell imaging

We have synthesized a new probe 5-((anthracen-9-ylmethylene) amino)quinolin-10-ol (ANQ) based on anthracene platform. The probe was tested for its sensing behavior toward heavy metal ions Hg²⁺, Pb²⁺, light metal Al³⁺ ion, alkali, alkaline earth, and transition metal ions by UV–visible and fluorescent techniques in ACN/H₂O mixture buffered with HEPES (pH 7.4). It shows high selectivity toward sensing Pb²⁺/Al³⁺ metal ions. Importantly, 10-fold and 5- fold fluorescence enhancement at 429 nm was observed for probe upon complexation with Pb²⁺ and Al³⁺ ions, respectively. This fluorescence enhancement is attributable to the prevention of photoinduced electron transfer. The photonic studies indicate that the probe can be adopted as a sensitive fluorescent chemosensor for Pb²⁺ and Al³⁺ ions.     

Retention studies on uranium, thorium and lanthanides with amide modified reverse phase support and its applications

The retention behaviour of uranium and thorium was investigated on modified reverse phase supports using 3-oxo-pentanedioicacid bis-[bis-(2-ethyl-hexyl)-amide (OPAEHA), 3-oxo-pentanedioicacid bis diisobutyl amide (OPAIBA) and bis-2-ethylhexyl succinamic acid (BEHSA). alpha-Hydroxy isobutyric acid (alpha-HIBA) was employed as the complexing reagent for elution. Elution profiles of uranium and thorium were studied as a function of the modifier concentration, mobile phase composition and its pH. Based on these investigations, a novel high performance liquid chromatography (HPLC) based separation technique was developed using BEHSA modified support for the isolation and quantitative determination of lanthanides as a group in uranium matrix. Hundreds of samples obtained from pyrochemical reprocessing of molten salts containing lanthanides in uranium matrix (e.g. 1:20,000) were separated and determined within 7 min using the coated support. The advantage of the present HPLC technique lies in the simultaneous separation and assay of total lanthanides and uranium whereas other analytical methods necessitate the separation of uranium matrix prior to lanthanide assay.