Materials Literature
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Rational engineering of enzymes involves introducing key amino acids guided by a knowledge of protein structure to effect a desirable change in function. To date, all successful attempts to change specificity have been limited to substituting individual amino acids within a protein fold. However, the infant field of p…
To test whether the structure of a protein is determined in a manner akin to the assembly of a jigsaw puzzle, up to 10 adjacent residues within the core of T4 lysozyme were replaced by methionine. Such variants are active and fold cooperatively with progressively reduced stability. The structure of a seven-methionine…
Infrared and Raman spectra of lithium ammonium tartrate monohydrate were obtained in the frequency region at temperatures of 15 - 300 K. No soft phonon mode was observed, so the ferroelastic and ferroelectric phase transition at is of order - disorder type. The ordering of atoms below produces pronounced decreases in…
The frequency of optically excited plasmon oscillations in a metal cluster is studied as a function of cluster size. The model is based on the fact that a sphere filled with free-electron gas forms a cavity with size-dependent eigenfrequencies of the optically excitable TM plasmons. Excitation of plasmon resonances by…
The early stages of nucleation and growth in a mixture of high polymers were studied by time-resolved neutron scattering. During the first 160 min, a slow clustering was evident, indicating a buildup of concentration fluctuations. The clusters formed at the end of this stage had the characteristics of ``critical nucle…
For the first time quasicrystal surfaces produced by in situ cleavage in ultrahigh vacuum have been investigated by scanning tunneling microscopy. Twofold and fivefold surfaces of icosahedral AlPdMn single quasicrystals have been studied. The surfaces were found to be rough. Their structure is determined by cluster ag…
Low dielectric fluorocarbon/SiO2 composite films are developed that exhibit good thermal stability and low dielectric constant by using hexamethyldisiloxane (HMDSO) and prefluorobenzene (C6F6) as the monomer source gases, and argon and oxygen as the carrier gases in a dual frequency, inductively-coupled high-density p…
High-temperature surface metallization of Si(100) is observed at $T>900\mathrm{K}$ by high-resolution electron-energy-loss and ultraviolet photoemission spectroscopy. Metallization takes place well below the incomplete surface melting temperature and is consistent with the Si dimer dynamics, characterized by an ins…
Total Internal Reflection Fluorescence Spectroscopy, A.J. de Mello Total Internal Reflection Fluorescence Spectroscopy of Biomaterials, L.R. Fisher Surface Plasmon Resonance - Theory and Experimental Considerations, J. Davies and I. Faulkner Flow Cell Design Considerations for SPR Measurements, J. Davies and L. Skelto…
By using spin-polarized secondary electron spectroscopy, we have found that the surface of FeO(111) prepared by oxidation of Fe(110) is ferromagnetically ordered above the bulk N\'eel temperature of 198 K. A possible cause of the ordering is the reconstruction of a polar FeO(111) surface to reduce electrostatic surfac…
Universal curves are constructed that provide an immediate determination of the effect of a series resistor on the electron emission from a field emitter. These curves are applicable to both the low current and high current regime. The effects of space charge and of the series resistor are apparent from these curves,…
We report on electroluminescence at room temperature from forward biased n+–p silicon diodes containing high densities (108–109 cm−2) of dislocations at the junction interface. In addition to electroluminescence from band-to-band transitions, we observe a signal with a comparable intensity peaked at ∼1.6 μm (0.78 eV).…
The region of parameter space (acoustic pressure ${P}_{a}$, bubble radius ${R}_{0}$) in which stable single bubble sonoluminescence (SBSL) occurs in an air-water system is a small fraction of that which is accessible. This is due to the existence of an island of dissolution at high ${P}_{a}$ and small ${R}_{0}$. For d…
High energy resolution inelastic x-ray scattering measurements in the $1--6{\mathrm{nm}}^{\ensuremath{-}1}$ momentum transfer ( $Q$) region in vitreous silica ( $v{\ensuremath{-}\mathrm{S}\mathrm{i}\mathrm{O}}_{2}$) at $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1050\mathrm{K}$ show the existence of collectiv…
Polycrystalline thin films of Ba(ZrxTi1−x)O3 with x=0–0.4 and a thickness of ∼180 nm were deposited on platinum-coated silicon substrates by rf magnetron sputtering at 500 °C. Ba-rich targets were used to prepare films of stoichiometric composition. The film having x=0.12 exhibited a satisfactory dielectric property o…
We collect and spectrally resolve photoluminescence from single CdSe nanocrystallite quantum dots. The elimination of spectral inhomogeneities reveals resolution limited spectral linewidths ( $<120\ensuremath{\mu}\mathrm{eV}$ at 10 K) more than 50 times narrower than expected from ensemble measurements. Light drive…
In this work, we investigate the suitability of models based solely on continuum hydrodynamics for Stokesian Dynamics simulations of sheared suspensions of non-Brownian hard spheres. The suspensions of interest consist of monolayers of uniform rigid spheres subjected to a linear shear field. Areal fractions ranged fro…
Copolymer resins were synthesized by the mixed condensation of resorcinol–CH2O, resorcinol–aniline–CH2O, resorcinol–aniline–thiourea–CH2O, and resorcinol–aniline–urea–thiourea–CH2O with a view to develop synthetic resins having improved properties and performance like toughness, mechanical properties, thermal resistan…
The reaction of Na[V -I (CO) 6 ]·2diglyme, V I (C 5 H 5 )(CO) 4, [Et 4 N][V -I (CO) 6 ], V o (C 5 H 5 )(C 7 H 7 ), V o (CO) 6, [V I (C 6 H 6 ) 2 ][PF 6 ], [V I- (C 6 H 6 ) 2 ][V -I (CO) 6 ], V II (C 5 H 5 ) 2, [V II (NCMe) 6 ][BPh 4 ] 2, [V II- (NCMe) 6 ]-[V -I (CO) 6 ] 2, and [V II (THF) 6 ][V I (CO) 6 ] 2, with tetr…
Some Fe(II)-l,2,4-triazole derivatives exhibit very abrupt thermally induced spin transitions around room temperature, accompanied by a well pronounced change of color, between purple in the low-spin (LS) state and white in the high-spin (HS) state. Our objective is to obtain such compounds for which the ambiant tempe…