Materials Literature
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Bioassay-directed fractionation of an anti-inflammatory CHCl(3)-MeOH (9:1) extract of leaves of Vernonia colorata, using a carrageenan-induced rat paw model, led to the isolation of six new compounds (1-6). These were assigned as two new androst-8-en glycosides, 3-O-[beta-d-galactopyranosyl-(1-2)-[beta-d-glucopyranosy…
We have investigated the adsorption structures and thermal desorption behavior of C 2 H 4 on Ge(100) using scanning tunneling microscopy (STM) and temperature programmed desorption (TPD) under ultrahigh vacuum (UHV). Ethylene molecules adsorb in two distinct bonding geometries: (i) on top of a single Ge−Ge dimer (on-t…
Two new volumetric sorption techniques have been developed to measure thermodynamic and mass-transport properties in polymer−solvent systems at elevated pressures. They are both variations of the pressure-decay technique and differ in how the initial gas density is measured. In the first and simplest variation, the in…
Using an atomic force microscope (AFM), we have investigated the interaction forces exerted by latex particles bearing densely grafted polymer brushes consisting of poly(N,N-dimethylacrylamide) (PDMA), poly(methoxyethylacrylamide) (PMEA), poly(N-isopropylacrylamide) (PNIPAM), and PMEA-b-PNIPAM in aqueous media (good s…
We apply the semiempirical nonlocal pseudopotential method to the investigation of prospects for direct carrier multiplication (DCM) in neutral and negatively charged CdSe nanocrystals. In this process, known in the bulk as impact ionization, a highly excited carrier transfers, upon relaxation to the band edge, its ex…
ADVERTISEMENT RETURN TO ISSUECommunicationNEXTA Novel Method for Preparation of Disorderly Exfoliated Epoxy/Clay NanocompositeJun Ma, Zhong-Zhen Yu, Qing-Xin Zhang, Xiao-Lin Xie, Yiu-Wing Mai, and Ian LuckView Author Information Centre for Advanced Materials Technology (CAMT), School of Aerospace, Mechanical and Mecha…
Here, we report the first example of transition metal-catalyzed one-pot synthesis of water-soluble dendritic molecular nanocarriers behaving like unimolecular micelles. Using the palladium-alpha-diimine chain walking catalyst, copolymerization of ethylene and comonomer 3 afforded, in one step, amphiphilic copolymer 1…
In our previous study, in vitro evolution of type II polyhydroxyalkanoate (PHA) synthase (PhaC1Ps) from Pseudomonas sp. 61-3 yielded eleven mutant enzymes capable of synthesizing homopolymer of (R)-3-hydroxybutyrate [P(3HB)] in recombinant Escherichia coli JM109. These recombinant strains were capable of accumulating…
A noble metal ion (Pt 2+ and Pd 2+ ) adsorbent with uniform mesopore channels was prepared by grafting a thiol functional group, (3-mercaptopropyl)trimethoxysilane (MPTMS), onto ordered mesoporous silica, SBA-15. Results show that the ordered mesostructure of SBA-15 was retained after modification and the thiol functi…
Nanocrystalline films of La-doped CaB$_6$ have been fabricated by using a rf-magnetron sputtering. Lattice expansion of up to 6% with respect to the bulk value was observed along the direction perpendicular to the film plane, which arises from the trapping of Ar gas into the film. Large ferromagnetic moment of 3 ~ 4 B…
We report our efforts to understand the passivation behavior of bovine serum albumin (BSA) and its structural changes at interfaces using X-ray photoelectron spectroscopy and contact angle measurements. The work investigated protein adsorption on two surfaces with widely different surface free energies. We investigate…
A theoretical prediction of the nonlinear optical (NLO) properties of the hydrogen fluoride trimer anion (FH) 2 {e}(HF) reveals that this electron-solvated cluster possesses exceptionally large static first hyperpolarizability. Using the d-aug-cc-pVDZ basis set supplemented with diffusive bond functions (BF), we obtai…
The full potential linearized augmented plane wave (FLAPW) method was used to study the crystal structure and electronic structure properties of PbFe0.5Nb0.5O3 (PFN). The optimized crystal structure, density of states, band structure and electron density distribution have been obtained to understand the ferroelectric…
Volume expansion $ΔV / V$ associated with the spin reorientation process of Nd$_2$Fe$_{14}$B-type compounds has been investigated in terms of simple crystalline-electric-field (CEF) model. In this system, $ΔV / V$ is shown to be a direct measure of second order CEF energy. Calculated anomalies in $ΔV / V$ associated w…
Chirality-driven microphase-separated morphology, poly(l-lactide) (PLLA) left-handed nanohelices hexagonally packed in PS matrix, was obtained from chiral diblock copolymers, poly(styrene)-b-poly(l-lactide). This is perhaps for the first time; the helical superstructures of chiral block copolymers were generated in th…
An in situ method is introduced for the study of nucleation and growth of crystals using the size-dependent properties of a given system in the transition size regime from molecular species to bulk sized crystals. The real-time measurements for the first system studied, a CdSe one, were carried out by recording the ab…
The replacement of the phenyl rings at the 5,5'-positions of a bis(dipyrrinato)zinc complex with mesityl groups transforms the molecule from a very weak emitter that deactivates rapidly after photoexcitation (Phif = 0.006; tau approximately 90 ps) to a highly fluorescent chromophore with a long-lived singlet excited s…
X-ray absorption near-edge spectra and temperature-programmed oxidation and reduction data demonstrate that Au(I) and Au(0) are both present in working MgO-supported gold catalysts for CO oxidation. EXAFS data indicate gold clusters with essentially the same average diameter (about 30 A) in each catalyst sample. Thus,…
This paper reports detailed synthesis and characterization of polymers with functional groups for chemoselective immobilization. Various types of 1,4-diiodo-2,5-dialkoxybenzene monomers containing hydrophobic and hydrophilic groups with chemoselective functional group pairs were synthesized and copolymerized with 1,2-…
Selective solvent crazing is proposed as a novel method for depth profiling and obtaining three-dimensional information by AFM on the microphase morphology in ultrathin polystyrene/poly(methyl methacrylate) (P(S- b -MMA)) diblock copolymer films on silicon substrate. To remove selectively one of the blocks, chain scis…