Selective Curcuminoid Separation and Detection via Nickel Complexation and Adsorptive Stripping Voltammetry

Curcumin is a widely studied biologically active redox molecule. Although sensitive, electrochemical methods are commonly hindered by their lack of specificity. This article demonstrates how curcumin may be readily separated from other structurally and electrochemically similar redox moieties. This separation is achieved through exploitation of the molecules diketone functionality providing a route for its selective chelation to nickel(II). Recovery of the curcumin from the nickel complex is achieved simply and quantitatively through acidification of the precipitate. Adsorptive stripping voltammetry at a carbon screen‐printed electrode (SPE) is utilised both as a method for evidencing the effectiveness of the separation technique but further as a procedure for the analytical quantification of the curcumin concentration.     

Rapid preparation of cellulose nanofibre sheet

Cellulose nanofibre sheet materials are of great interest in various applications because of their excellent properties, but are difficult to prepare rapidly and as large sheets. This paper describes a quick preparation procedure for preparing optically transparent, flat and smooth nanofibre sheets, which is much quicker than existing methods. Low permeability, optical transparency, high strength and high density show that nanofibres were well dispersed. The preparation time for the nanofibre sheet produced here was 10 min whereas the preparation times reported in literature is above 1 h. The decrease in sheet preparation time suggests that this method can be used for commercial applications.     

Effect of tethered and free microfibrillated cellulose (MFC) on the properties of paper composites

High strength and low gas permeability cellulosic composites were produced using the papermaking technology with a commercial microfibrillated cellulose (MFC). The effect of blending MFC with hardwood fibers was compared to the direct refining of the fibers with and without polyamideamine-epichlorohydrin (PAE) addition. The addition of MFC, free or tethered, to pulp fibers combined with PAE can increase the dry strength and wet strength of cellulosic materials by an order of magnitude. Air permeability of the composites decreases by up to orders four of magnitude with MFC addition. The hypothesis that refining wood fibers can produce tethered MFC which provides equivalent strength properties but significant drainage benefits was proven. Furthermore, major benefits in paper formation uniformity (fiber distribution homogeneity) were achieved with refined fibers.     

Reactivity trends of cobalt(III) complexes towards various amino acids based on the properties of the amino acid alkyl chains

The reactivity of the cobalt(III) complexes dichlorido[tris(2‐aminoethyl)amine]cobalt(III) chloride, [CoCl₂(tren)]Cl, and dichlorido(triethylenetetramine)cobalt(III) chloride, [CoCl₂(trien)]Cl, towards different amino acids (l ‐proline, l ‐asparagine, l ‐histidine and l ‐aspartic acid) was explored in detail. This study presents the crystal structures of three amino acidate cobalt(III) complexes, namely, (l ‐prolinato‐κ²N,O)[tris(2‐aminoethyl)amine‐κ⁴N,N′,N′′,N′′′]cobalt(III) diiodide monohydrate, [Co(C₅H₈NO₂)(C₆H₁₈N₄)]I₂·H₂O, I , (l ‐asparaginato‐κ²N,O)[tris(2‐aminoethyl)amine‐κ⁴N,N′,N′′,N′′′]cobalt(III) chloride perchlorate, [Co(C₄H₇N₂O₃)(C₆H₁₈N₄)](Cl)(ClO₄), II , and (l ‐prolinato‐κ²N,O)(triethylenetetramine‐κ⁴N,N′,N′′,N′′′)cobalt(III) chloride perchlorate, [Co(C₄H₇N₂O₃)(C₆H₁₈N₄)](Cl)(ClO₄), V . The syntheses of the complexes were followed by characterization using UV–Vis spectroscopy of the reaction mixtures and the initial rates of reaction were obtained by calculating the slopes of absorbance versus time plots. The initial rates suggest a stronger reactivity and hence greater affinity of the cobalt(III) complexes towards basic amino acids. The biocompatibility of the complexes was also assessed by evaluating the cytotoxicity of the complexes on cultured normal human fibroblast cells (WS1) in vitro. The compounds were found to be nontoxic after 24 h of incubation at concentrations up to 25 mM.     

Paper engineered with cellulosic additives: effect of length scale

Composites of cellulose fibers were made with paper-making technology. Two types of microfibrillated cellulose (MFC), obtained by with either homogenization or ball milling, were blended with hardwood fibers to give composites having high strength and low air permeability. The strengthening effects of the MFCs were compared with strengthening by cellulose microparticles (CMPs) made by cryogenic milling, with and without polyamideamine-epichlorohydrin addition. The MFC from homogenization was fully retained on the fiber web due to a broad size distribution; in contrast, the retention ratio for MFC produced by ball milling was lower than 50 % because of its smaller particle size. The small size caused the resulting paper to display a more compact and denser structure. The main distinction between the papers made with the two types of MFC was the elongation at break under wet conditions, suggesting that they reinforce the paper in different ways. On the other hand, CMPs act as mechanical debonders and could find application in tissue paper, increasing paper bulk and decreasing the density and thus improve tissue softness.     

Nanorod Aspect Ratios Determined by the Nano‐Impact Technique

The in situ electrochemical sizing of individual gold nanorods is reported. Through the combination of electrochemical dissolution and the use of a surface‐bound redox tag, the volume and surface area of the nanorods are measured, and provide the aspect ratio and the size of the nanorods. Excellent independent agreement is found with electron microscopy analysis of the nanorods, establishing the application of nano‐impact experiments for the sizing of anisotropic nanomaterials.