Gel Sculpture: Moldable,Load‐Bearing and Self‐Healing Non‐Polymeric Supramolecular Gel Derived from a Simple Organic Salt

An easy access to a library of simple organic salts derived from tert‐butoxycarbonyl (Boc)‐protected L ‐amino acids and two secondary amines (dicyclohexyl‐ and dibenzyl amine) are synthesized following a supramolecular synthon rationale to generate a new series of low molecular weight gelators (LMWGs). Out of the 12 salts that we prepared, the nitrobenzene gel of dicyclohexylammonium Boc‐glycinate ( GLY.1 ) displayed remarkable load‐bearing, moldable and self‐healing properties. These remarkable properties displayed by GLY.1 and the inability to display such properties by its dibenzylammonium counterpart ( GLY.2 ) were explained using microscopic and rheological data. Single crystal structures of eight salts displayed the presence of a 1D hydrogen‐bonded network (HBN) that is believed to be important in gelation. Powder X‐ray diffraction in combination with the single crystal X‐ray structure of GLY.1 clearly established the presence of a 1D hydrogen‐bonded network in the xerogel of the nitrobenzene gel of GLY.1 . The fact that such remarkable properties arising from an easily accessible (salt formation) small molecule are due to supramolecular (non‐covalent) interactions is quite intriguing and such easily synthesizable materials may be useful in stress‐bearing and other applications.     

NOR and NAND gates using two photon absorption in silicon wire waveguide

Ultrafast all-optical NOR gate based on two photon absorption (2PA) process in SOI waveguide is already established. We have designed NAND gate also based on this process with a novel waveguide coupler structure. Power attenuation due to 2PA process and the working of these gates is developed with FDTD simulation. Dominant 2PA process is incorporated in FDTD update equations and it is shown that the influence of high intensity pump pulses on a different frequency continuous probe beam can be utilized to form NOR as well as NAND gates.     

Vertical Sediment Concentration Distribution in High-Concentrated Flows: An Analytical Solution Using Homotopy Analysis Method

Transport of suspended sediment in open channel flow has an enormous impact on real life situations, viz. control and management of reservoir sedimentation, geomorphic evolution such as dunes, rivers, and coastlines etc. Transport entails advection and diffusion. Turbulent diffusion is governed by the concept of Fick's law, which is based on the molecular diffusion theory, and the equation that represents the distribution of sediment concentration is the advection-diffusion equation. The study uses the existing governing equation which considers different phases for solid and fluid, and then couples the two phases. To deal with high-concentrated flow, sediment and turbulent diffusion coefficients are taken to be different from each other. The effect of hindered settling on sediment particles is incorporated in the governing equation, which makes the equation highly non-linear. This study derives an explicit closed-form analytical solution to the generalized one-dimensional diffusion equation representing the vertical sediment concentration distribution with an arbitrary turbulent diffusion coefficient profile. The solution is obtained by Homotopy Analysis Method, which does not rely on the small parameters present in the equation. Finally, the solution is validated by comparing it with the implicit solution and the numerical solution. A relevant set of laboratory data is selected to check the applicability of the model, and a close agreement shows the potential of the model in the context of application to high-concentrated sediment-laden open channel flow.     

A Novel Technique of Synthesis of Highly Fluorescent Carbon Nanoparticles from Broth Constituent and In-vivo Bioimaging of <Emphasis Type="Italic">C. elegans</Emphasis>

Here we have demonstrated a novel single step technique of synthesis of highly fluorescent carbon nanoparticles (CNPs) from broth constituent and in vivo bioimaging of Caenorhabditis elegans (C. elegans) with the synthesized CNPs has been presented. The synthesized CNPs has been characterized by the UV-visible (UV-Vis) absorption spectroscopy, transmission electron microscopy (TEM) and Raman studies. The sp ² cluster size of the synthesized samples has been determined from the measured Raman spectra by fitting it with the theoretical skew Lorentzian (Breit-Wigner- Fano (BWF)) line shape. The synthesised materials are showing excitation wavelength dependent tunable photoluminescence (PL) emission characteristics with a high quantum yield (QY) of 3 % at a very low concentration of CNPs. A remarkable increase in the intensity of PL emission from 16 % to 39 % in C. elegans has also been observed when the feeding concentration of CNPs to C. elegans is increased from 0.025 % to 0.1 % (w/v). The non-toxicity and water solubility of the synthesized material makes it ideal candidate for bioimaging.     

Photoinduced electron transfer between quinones and amines in micellar media: Tuning the Marcus inversion region

Electron transfer (ET) rates between quinone acceptors and amine donors in micellar media show Marcus inversion behavior on correlating with the free energy changes of the ET reactions. The onset of Marcus inversion in these systems is seen to be tuned by about 0.25 eV by changing the type of the micelle. The results are rationalized on the basis of two-dimensional ET theory where ET occurs along intramolecular coordinate with non-equilibrium configuration along solvation coordinate. Maximum ET rates are seen to vary by about one order of magnitude in different micelles, and are attributed to the micelle-dependent changes in the separations of the interacting quinone–amine pairs. Tunings of Marcus inversion and ET rates by changing micellar microenvironments have been observed and suggested to have useful implications in different applied areas.     

Quantitative distinction between competing intramolecular bond twisting and solvent relaxation dynamics: an ultrafast study

Often an intramolecular relaxation process takes place in a time scale similar to that of the solvent relaxation process. Under these circumstances the dynamic Stokes' shift of the probe can be modulated by the combined effect of these two relaxation processes. In the present article we have studied ultrafast solvent relaxation using three different coumarin dyes and proposed a methodology for the quantitative separation of the dynamics of two competing processes, namely, solvent relaxation and bond twisting, that take place simultaneously in the present systems.     

Determination of vitamin B12 in infant formula and adult nutritionals by surface plasmon resonance: First Action 2011.16 (test kit method)

At the "Standards Development and International Harmonization: AOAC INTERNATIONAL Mid-Year Meeting" on June 29, 2011, an Expert Review Panel (ERP) agreed to further examine AOAC Official Method 2011.01, "Determination of Vitamin B12 by Surface Plasmon Resonance," for use with infant formula and adult nutritionals. The original collaborative study was conducted using the Biacore Q biosensor instrument and the Biacore Q Qflex Kit Vitamin B12 PI. Samples included in the study were infant formula, cereals, premixes, vitamin tablets, dietary supplements, and baby food. Eleven laboratories participated in the collaborative study. The results demonstrated a repeatability RSD (RSDr) of 1.59-27.8 and HorRat values for reproducibility of 0.34-1.89 in samples with levels ranging from ppm to ppb. The assay studied is a label-free protein binding-based assay that uses the principle of surface plasmon resonance to measure the interaction between vitamin B12 and a specific binding protein by passing a portion of the prepared sample extract combined with binding protein solution across a functionalized sensor chip. The response from the functionalized sensor chip is given as free-binding protein, as the mixture binds to the prepared surface of the chip. The ready-to-use Qflex Kit Vitamin B12 PI provides the reagents and accessories necessary to perform this assay. AOAC Method 2011.01 was approved by the AOAC Method Committee on Food Nutrition for Official First Action status, applicable to a wide range of food products, dietary supplements, and multivitamin premixes. After evaluation of the validation data available, an ERP agreed in June 2011 that the method meets standard method performance requirements, as articulated by the Stakeholder Panel on Infant Formula and Adult Nutritionals. The ERP granted the method First Action status, applicable to infant formula and adult/pediatric nutritional formula.     

Simulation of two photon absorption in silicon wire waveguide for implementation of all optical logic gates

All optical switching action of silicon wire waveguide for the design of the proposed logic gates is simulated. This is one possible building block of the future all optical computer or photonic devices. All optical logic gates NOT, NAND and AND gates using two photon absorption in silicon wire waveguide are presented. Use of ultra short pulse has negligible free carrier absorption effect; hence the operating speed of the gates is very high and has potential application in photonic processing. NAND gate is universal one and thus one can perform any logical operation using this. The device (Si wire WG) requires low energy pulse and is ultrafast one.