Materials Literature
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Abstract A series of novel block polymers of polyurethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, M n = 1000), isophrone diisocyanate (IPDI), and 2,2′‐dimethylol propionic acid (DMPA), followed by ionizi…
Antiferroelectric (AFE), ferroelectric (FE), or relaxor states can appear in $\mathrm{Pb}({\mathrm{In}}_{1∕2}{\mathrm{Nb}}_{1∕2}){\mathrm{O}}_{3}$ (PIN) depending on the perovskite B-site randomness. We studied the effects of this randomness on the dynamics of PIN by high resolution inelastic x-ray scattering using or…
In order to relate single fiber behavior to multiple fiber behavior in composites, fast-fracture tensile strength, creep, and stress-rupture studies were conducted on advanced SiC fiber multifilament tows in the temperature range from 20 to 1400 C in air as well as in inert environments. For conditions of small fiber…
Abstract Nucleation of protein crystals by gold nanoparticles was observed. Lysozyme and ferritin were used as model proteins. The effect was established with uncoated gold nanoparticles and with gold nanoparticles coated by 16‐mercaptodecanoic acid. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Abstract Exfoliated poly(vinyl acetate) (PVAc)/montmorillonite (MMT) and poly(vinyl acetate‐ co ‐glycidyl methacrylate) [P(VAc‐ co ‐GMA)]/MMT nanocomposite latices, prepared by soap‐free emulsion polymerization, were able to be cast into films, and the latter was crosslinked with diethylene triamine as a curing agent.…
The oxidation of methanol on both ZrO 2 and V/ZrO 2 was investigated using temperature-programmed experiments together with in situ infrared spectroscopy. Characterization of V/ZrO 2 after calcination by Raman spectroscopy and XANES shows that the vanadium is present as isolated VO 4 units in a distorted tetrahedral g…
Unveiling sequence-stability and structure-stability relationships is a major goal of protein chemistry and structural biology. Despite the enormous efforts devoted, answers to these issues remain elusive. In principle, collagen represents an ideal system for such investigations due to its simplified sequence and regu…
We describe the synthesis of small (2-nm diameter) gold nanoparticles densely functionalized with thiolated DNA (DNA-Au NPs) and a method to separate these particles from excess free DNA after synthesis. The separation method utilizes the thermodynamically enhanced binding properties of 2-nm DNA-Au NPs, compared to fr…
Variable temperature 39 K and 2 H nuclear magnetic resonance (VT NMR) spectroscopy of K + -saturated hectorite, a prototypical smectite clay, provides new insight into the relationships between the structural and dynamical behavior of K + and H 2 O in confinement and at surfaces. In d = 10 Å K-exchanged hectorite, int…
Polymers represent the largest and versatile class of biomaterials being extensively applied in multitude of biomedical applications. This versatility is attributed to the relative ease with which polymers can be designed and prepared with a wide variety of structures and appropriate physical, chemical, surface and bi…
We performed a systematic measurement of the dielectric function of Si nanoslabs as a function of their thickness using spectroscopic ellipsometry from $0.73\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ $(1700\phantom{\rule{0.3em}{0ex}}\mathrm{nm})\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}4.58\phantom{\…
AIMS: Magnetic nanoparticles have been studied widely as MRI contrast agents to increase the sensitivity of this technique. This work describes the synthesis and characterization of magnetic nanotubes (MNTs) as a novel MRI contrast agent. METHODS: MNTs with high saturation magnetization were fabricated by the synthesi…
We compare the photochemical stability of the nonlinear optical chromophore configurationally locked polyene 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) embedded in a polymeric matrix and in a single-crystalline configuration. The results show that, under resonant light…
A new, high strength (2.4 GPa) polycrystalline alumina fiber has recently been developed at 3M (trade name Nextel 610). The high temperature creep properties and creep rupture mechanisms were determined in the temperature range 900°C −1200°C. The creep rate was proportional to the cube of stress and was controlled by…
Abstract Electrocopolymerization of 3,4‐ethylenedioxythiophene (EDOT) and 5‐methylindole (5MeIn) was successfully carried out in acetonitrile containing lithium perchlorate as supporting electrolyte although the oxidation potentials of 5MeIn and EDOT were quite different. The influence of feed ratios and applied poten…
Ion-promoted, automorphogenic, and stoichiometric self-assembly of a hexameric, Ru-based macrocycle and a dendrimer produces a stable nanofiber. A structurally related larger 3rd generation dendrimer was reacted with [(112+)(PF6−)12] to afford a neutral, sphere-like motif. These polyanionic counterions lead to ion-pai…
We discuss simulations of a simple model for polymer blends in the framework of the Rouse model. At odds with standard predictions, large dynamic asymmetry between the two components induces strong nonexponentiality of the Rouse modes for the fast component. Despite chains being much shorter than the entanglement leng…
In Archaea, acetate formation and ATP synthesis from acetyl-CoA is catalyzed by an unusual ADP-forming acetyl-CoA synthetase (ACD) (acetyl-CoA + ADP + P(i) acetate + ATP + HS-CoA) catalyzing the formation of acetate from acetyl-CoA and concomitant ATP synthesis by the mechanism of substrate level phosphorylation. ACD…
Biological passivation of porous silicon (PSi)-based optical devices is demonstrated. Infiltration by small amphiphilic fungal proteins called HFBs changes the wettability of the PSi surface (see figure) and protects the sponge-like structure against dissolution by basic solutions. This protein membrane leaves the sen…
Based on perturbation theory and local-density-functional calculations, we study the effect of atomic-scale defects, whose potentials vary on the scale of interatomic distance, on the electronic structure of graphene in the region of low energies. If defects are identical, for example, vacancies at the same sublattice…