Materials Literature
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Abstract The three series of polyether polyurethane cationomers based on MDI, HDI, and TDI that are the subject of Part I, undergo emulsification (or phase inversion) on addition of water to solutions in MEK. The phase inversion mechanism depends on the structure of hard segment, ionic content, and dispersion temperat…
Absorption saturation and luminescence measurements on semiconductor-doped glasses are reported, and the results are analyzed in terms of a band-filling model that is found to explain adequately the absorption data obtained with fresh as well as with photodarkened samples. With this model the free-carrier densities ar…
The interaction of hydrogen and deuterium with the (OOO1) surface of beryllium has been investigated using resolution electron energy loss spectroscopy, thermal desorption spectroscopy, and work function measurements. Dissociative adsorption of molecular hydrogen is an activated process, and recombinative desorption o…
The aging behaviour of quenched Zn–Al alloys containing small additions of copper was studied using metallography, hardness measurements, and quantitative X-ray diffraction. The kinetics of decomposition of supersaturated α/α′ and β phases were determined and related to structural changes. It was found that the Avrami…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNeutron reflectivity study of block copolymers adsorbed from solutionS. K. Satija, C. F. Majkrzak, Thomas P. Russell, S. K. Sinha, E. B. Sirota, and G. J. HughesCite this: Macromolecules 1990, 23, 16, 3860–3864Publication Date (Print):August 1, 1990Publication History Publis…
Defect creation in 24% densified, high-OH-concentration amorphous ${\mathrm{SiO}}_{2}$ has been studied using 248-nm excimer laser radiation. Combining laser and \ensuremath{\gamma}-ray radiation data, we find correlated growth of oxygen-vacancy and nonbridging oxygen-hole-center defects over a range of concentration…
With short Au…︁Au contacts of 2.9 Å, the “dimeric” structure of the polymeric [AuSe5]⊖ anion 1 in KAuSe5 provides a further example of d10–d10 interactions in the solid state. KAuSe5 is formed as reddish-brown, needlelike crystals from a polychalcogenide melt (K2Se: Au:Se = 2:1 :8); if the amount of K2Se is reduced to…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new mechanism of toughening glassy polymers. 1. Experimental proceduresO. S. Gebizlioglu, H. W. Beckham, Ali S. Argon, R. E. Cohen, and H. R. BrownCite this: Macromolecules 1990, 23, 17, 3968–3974Publication Date (Print):August 1, 1990Publication History Published online1…
An automatic diffraction data collection system with an imaging plate has been developed for protein crystallography. The system works in a similar way to the conventional rotation camera method, but in full online mode. After exposure to the X-ray beam, the imaging plate (100 mm radius) rotates whilst a reading head…
The limitations and advantages of particular dyes for labelling proteins and other biological materials are discussed. Methods available for conjugating dyes to proteins are outlined. Following a discussion of double labelling methods the use of photoactivatable fluorochromes and time resolved fluorescence methodologi…
A correlation is observed between the ESR spectra (at 1.12 GHz) and the magnetization inversions of the spin glass AgMn for a Mn concentration of 8.3 at. %. This is because of rearrangement of the spin system during the magnetization inversions. The widths of the ESR lines W↑ und W↓ which correlate, respectively, with…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure, magnetism, and electronic and EPR spectroscopies of bis(2-aminopyrimidinium) tetrachlorocuprate(II): a square-planar CuCl42- anion with semicoordinated cationic ligandsClaudia Zanchini and Roger D. WillettCite this: Inorg. Chem. 1990, 29, 16, 3027–3030Publ…
Abstract The electrical conductivity (σ) and thermoelectric power ( Q ) of polycrystalline lithiumcadmium ferrites having the chemical formula Li 0.5– x /2 Cd x Fe 2.5– x /2 O 4 where ( x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) have been investigated as a function of temperature. Lithium‐cadmium ferrite with x = 0.4 is fo…
These ferrites were prepared from Fe{sub 2}O{sub 3}, MO oxides (M = Ba,Sr,Pb) and MeO oxides (Me = Mg,Mn,Co,Zn). Chemical compositions of the main barium ferrites (M = Ba) are represented in a ternary diagram. The structures of these various compounds (M,Y,W,Z,X,U) are closely related. The simplest one is the compound…
The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to syn…
Ribonuclease H (RNase H) from Escherichia coli is an endonuclease that specifically degrades the RNAs of RNA:DNA hybrids. The enzyme is a single polypeptide chain of 155 amino acid residues, of which 4 are methionines. To solve the crystallographic three-dimensional structure of E. coli RNase H by the multi-wavelength…
2-(4-Amino-4-carboxybutyl)aziridine-2-carboxylic acid (3) (aziridino-DAP) was identified as the product of spontaneous hydrolysis of alpha-(halomethyl)diaminopimelic acids (alpha-halomethyl-DAPs) 2a-c. Under physiological conditions, 3 is an extremely potent irreversible inhibitor of the bacterial enzyme diaminopimeli…
Abstract Blends of bisphenol‐A polyarbonate (PC) and poly(ethylene terephthalate) (PET) has been investigated by differential scanning calorimetry and scanning electron microscopy. Blends were prepared by screw extrusion and solution casting with weight fractions of PC in the blends varying from 0.90 to 0.10. From the…
Single-crystal neutron-diffraction studies of PbTiO3, in its tetragonal (ferroelectric) phase at room temperature, at Tc - 60 K and at Tc - 20 K, and in its cubic phase at Tc+ 2 K, Tc + 50 K and Tc + 100 K, give evidence that the phase transition, at T, = 763 K, is order-disorder in character. In particular, the Pb at…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDynamics of the reaction of hydrogen peroxide with a water soluble non .mu.-oxo dimer forming iron(III) tetraphenylporphyrin. 2. The reaction of hydrogen peroxide with 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphinato iron(III) in aqueous solutionRick Panicucci a…