Formation of Supramolecular Nanostructures through in Situ Self-Assembly and Post-Assembly Modification of a Biocatalytically Constructed Dipeptide Hydrazide**

Aqueous self-assembly of short peptides has attracted growing attention for the construction of supramolecular materials for various bioapplications. Herein, we describe how the thermolysin-assisted biocatalytic construction of a dipeptide hydrazide from an N-protected amino acid and an amino acid hydrazide leads to the formation of thermally stable supramolecular hydrogels. In addition, we demonstrate the post-assembly modification of the supramolecular architectures constructed in situ tethering hydrazide groups as a chemical handle by means of fluorescence imaging.     

Chiral Interlocked Corrole Dimers Directly Linked at Inner Carbon Atoms of Confused Pyrrole Rings

A facile synthetic strategy towards conformationally stable chiral chromophores based on dimeric porphyrinoids has been established. A peculiar class of face-to-face intramolecularly interlocked corrole dimers were formed by the oxidative C−C coupling linked at the inner carbon sites upon simple treatment of copper(II) ions. Their intrinsic electronic structures were modulated by the peripheral corrole ring annulations, which lead to distinct optical properties and redox profiles. The stereogenic carbon centers implemented in the confused corrole skeleton provided a rationale for designing novel chiral materials.     

Ion-transfer voltammetry at a polarized room-temperature molten salt/water interface.

Tetraoctylammonium cation forms a room-temperature molten salt (RTMS) with 2,4,6-trinitrophenolate anion. The RTMS is immiscible with water (W) and forms a stable RTMS/W interface. It has been shown that the RTMS/W interface can be electrochemically polarized. A well-defined voltammetric wave due to the transfer of thiocyanate ion across the RTMS/W interface was observed within the potential window. This is the first example of a polarized RTMS/W interface.     

How is chiral symmetry restored at finite density?

Taking into account pseudoscalar as well as scalar condensates, we reexamine the chiral restoration path on the chiral manifold. We shall see both condensates coherently produce a density wave at a certain density, which delays chiral restoration as density or temperature is increased.     

Temporal analysis of products (TAP) study on oxygen storage properties over Pt−Rh/CeO2 catalyst

The oxygen storage capacity of CeO₂, Ce_0.9Pr_0.1O₂, Pt?Rh/CeO₂ and Pt?Rh/Ce_0.9Pr_0.1O₂ was investigated by conventional GC pulse method and transient pulse techniques. It is shown that incorporation of PrO_y into CeO₂ matrix strongly promotes oxygen storage capacity (OSC) measured using the transient pulse technique. The improvement of OSC at low temperature is observed in Pt?Rh loaded onto CeO₂ and Ce?Pr catalysts.     

Syntheses and characterization of 16‐arm star and star diblock copolymer and AB8 9‐miktoarm star copolymer via NMRP and ROP from dendritic multifunctional macroinitiators

A dendritic macroinitiator having 16 TEMPO‐based alkoxyamines, Star‐16 , was prepared by the reaction of a dendritic macroinitiator having eight TEMPO‐based alkoxyamines, [G‐3]‐OH , with 4,4′‐bis(chlorocarbonyl)biphenyl. The nitroxide‐mediated radical polymerization (NMRP) of styrene (St) from Star‐16 gave 16‐arm star polymers with PDI of 1.19–1.47, and NMPR of 4‐vinylpyridine from the 16‐arm star polymer gave 16‐arm star diblock copolymers with PDI of 1.30–1.43. The ring‐opening polymerization of ε‐caprolactone from [G‐3]‐OH and the subsequent NMRP of St gave AB₈ 9‐miktoarm star copolymers with PDI of 1.30–1.38. The benzyl ether linkages of the 16‐arm star polymers and the AB₈ 9‐miktoarm star copolymers were cleaved by treating with Me₃SiI, and the resultant poly(St) arms were investigated by size exclusion chromatography (SEC). The SEC results showed PDIs of 1.23–1.28 and 1.18–1.22 for the star polymers and miktoarm stars copolymers, respectively, showing that they have well‐controlled poly(St) arms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1159–1169, 2007.     

Performance evaluation of PVdF gel polymer electrolytes

A series of gel polymer electrolytes containing PVdF as homo polymer, a mixture of 1:1 Ethylene Carbonate (EC) : Propylene Carbonate (PC) as plasticizer and lithium-bistrifluoromethane sulphone imide [imide — LiN (CF₃SO₂)₂] has been developed. Amounts of polymer (PVdF), plasticizer and the imide lithium salt have been varied as a function of their weight ratio composition in this regard. Dimensionally stable films possessing appreciable room temperature conductivity values have been obtained with respect to certain weight ratio compositions. However, conductivity data have been recorded at different possible temperatures, i.e., from 20 °C to 65 °C. XRD and DSC studies were carried out to characterize the polymer films for better amorphicity and reduced glass transition temperature, respectively. The electrochemical interface stability of the PVdF based gel polymer electrolytes over a range of storage period (24 h – 10 days) have been investigated using A.C. impedance studies. Test cells containing Li/gel polymer electrolyte (GPE)/Li have been subjected to undergo 50 charge-discharge cycles in order to understand the electrochemical performance behaviour of the dimensionally stable films of superior conductivity. The observed capacity fade of less than 20% even after 50 cycles is in favour of the electrochemical stability of the gel polymer electrolyte containing 27.5% PVdF −67.5 % EC+PC −5% imide salt. Cyclic voltammetry studies establish the possibility of a reversible intercalation — deintercalation process involving Li⁺ ions through the gel polymer electrolyte.     

Calculation of heat transfer and uniformity of chemical amplification during post-exposure bake

Heat transfer in a resist-coated silicon wafer using a bake process is theoretically evaluated by modeling the three-dimensional diffusion process, focusing on the controllability of the lithographic performance of chemically amplified resists. Six models of various ambient conditions are used. The proximity gap between the hotplate and the wafer is found to have a dominant influence on the heat transfer process for the whole system. Because the atmosphere near the wafer acts as a thermal diffusion buffer layer, no temperature gradient occurs in the resist, even when it is subjected to convective heat transfer from the resist surface. Experimental results obtained by X-ray lithography confirm the calculation results.     

Phase Measurement Algorithm in Wavelength Scanned Fizeau Interferometer

Wavelength scanned interferometry allows the simultaneous measurement of top surface shape and optical thickness variation of a transparent object consisting of several parallel surfaces. Interference signals from these surfaces can be separated in frequency space, and their phases are detected by discrete Fourier analysis. However, these signal frequencies are shifted from the detection frequency by the refractive index dispersion of the object and a nonlinearity of the wavelength scanning. The Fourier analysis is sensitive to the detuning of the signal frequency and suffers from the multiple-beam interference noise. Conventional error-compensating algorithms cannot be applied to an object consisting of more than three reflecting surfaces. We derive a new 2N-1 sample error-compensating algorithm, which allows the phase detection of any order of harmonic frequency among the interference signals. The new algorithm suppresses the effect of signal frequency detuning as well as the multiple-beam interference noise and can be applied to the measurement of complex objects consisting of more than three reflecting surfaces.