The `Octopus' plate for protein crystallization under an electric field
A piece of equipment, adapted to a vapour-diffusion plate, has been designed to apply an external electrical field during the crystallization of protein samples.
Materials Literature
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Modification of ferromagnetism in semiconductors by molecular monolayers
We report that adsorption of monolayers of organic molecules onto the surface of ferromagnetic semiconductor heterostructures produces large, robust changes in their magnetic properties. The heterostructures have half a monolayer of MnAs embedded in GaAs, 50 Å beneath the surface. The molecules investigated are alkylp…
A new method for the determination of strain profiles in epitaxic thin films using X-ray diffraction
A new and versatile method is proposed for the determination of strain profiles in epitaxic thin films. It is based on the simulation of the X-ray diffraction (XRD) profiles using cubic B-spline functions to model the vertical lattice displacement profile. The lattice displacement profile, and consequently the strain…
Equilibrium and nonequilibrium molecular dynamics methods for determining solid–liquid phase coexistence at equilibrium
The solid–liquid equilibrium phase transition of a one-component Lennard-Jones system is determined by equilibrium and nonequilibrium molecular dynamics simulation methods. One method uses the observation that the scaling exponent of the pressure or energy of a shearing Lennard-Jones liquid is approximately 1 at the s…
Dinuclear and Octanuclear Mn(II) Complexes with μ2-C, μ2-N(Pyrrolide), and μ-η1:η5-(Pyrrolide) Bridges: A Structural and Magnetic Study
Reaction of the dinuclear [(CH2SiMe3)(mu-CH2SiMe3)Mn(THF)]2 (1) with an equivalent amount of 1,1-dipyrrolylcyclohexane afforded two compounds depending on the solvent employed. Reaction carried out in THF afforded the dinuclear ([1,1-(mu-C4H3N)(C4H3N)C6H10]Mn(THF)2)2.2(THF) (2) while reaction in toluene yielded the oc…
Preparation of Colloidal Gold
Since their introduction by Faulk and Taylor ( 1 ), colloidal gold probes have become widely used for immunocytochemical staining at the electron microscopic level. Many different methods of producing colloidal gold sols have been published ( 2 – 10 ). Gold sols are producing by boiling a solution of tetrachloroauric…
Production and Surface Modification of Polylactide-Based Polymeric Scaffolds for Soft-Tissue Engineering
Current research in the field of tissue engineering is focused on the development of appropriate strategies for repair and regeneration of biological tissues. Biological tissues consist of cells situated within a complex molecular framework known as the extracellular matrix (ECM) with an integrated vascular system for…
Cell Seeding of Polymer Scaffolds
Engineered tissues could form the basis for novel therapies for millions of patients who suffer from the loss of tissue or its function ( 1 ), and be used for in vitro studies of tissue development and normal and pathological function. One approach to tissue engineering involves seeding of a high density of uniformly…
SDS Polyacrylamide Gel Electrophoresis of Proteins
SDS-PAGE is the most widely used method for qualitatively analyzing protein mixtures. It is particularly useful for monitoring protein purification, and because the method is based on the separation of proteins according to size, the method can also be used to determine the relative molecular mass of proteins ( see No…
Protein Structure Calculation from NMR 267
Until 1984, structural information of biomolecules at atomic resolution could only be determined by X-ray diffraction techniques with protein single crystals ( 1 ). In the mid-1980s, Wüthrich and co-workers demonstrated that nuclear magnetic resonance (NMR) spectroscopy ( 2 ) could be used as a technique for protein s…
Ferroelectric and Antiferromagnetic Domain Wall
It has been experimentally confirmed that the ferroelectric (FEL) and antiferromagnetic (AFM) order-parameter in hexagonal YMnO 3 are coupled at the FEL domain boundary. A microscopic model for this clamping of the two order-parameters is proposed. The clamping can be understood as due to the change of exchange integr…
A two-dimensional Raman spectroscopic study on the structural changes of a polythiophene film during the cooling process
Raman spectra of a polythiophene film measured over a temperature range 298–98 K were analyzed using generalized two-dimensional correlation spectroscopy. In the 1600–1250 cm−1 region, the asynchronicity of the bands indicates the existence of different species in the investigated polythiophene sample. At least four d…
Diffuse neutron scattering in benzil, C14D10O2, using the time-of-flight Laue technique
Diffuse neutron scattering data have been recorded for the molecular crystal d -benzil, C 14 D 10 O 2 , using the time-of-flight Laue technique on the SXD and PRISMA instruments at ISIS. Using SXD it was possible to access a large fraction of the total three-dimensional reciprocal space out to a Q value of 15 Å −1 , u…
Time-Dependent Density Functional Theory Study on Polyazopyrrole and Polyazothiophene
Two narrow band gap polymers, polyazopyrrole (PAPY) and polyazothiophene (PATH), were theoretically investigated by means of time-dependent density functional theory (TDDFT) with the B3LYP functional. The most stable trans conformation that would be dominant in the infinite length polymer was discerned, and the chain…
Aggregation of a Zn(II) Complex of a Long-Chain Triester of meso-Tetrakis[p-carboxy]phenyl Porphyrin in Hydrocarbons: Structure of Tetrameric Rodlike Assemblies
It is shown that gelatinous solutions in cyclohexane of a Zn complex of a long-chain triester of meso -tetrakis[ p -carboxy]phenyl porphyrin (ZnP3) are made up of rodlike assemblies. The presence of both Zn atom and carboxylic function, reinforcing the usual π − π interactions, is determinant for the aggregation. The…
Atomistic modeling of deactivation and reactivation mechanisms in high-concentration boron profiles
We use kinetic nonlattice Monte Carlo atomistic simulations to investigate the physical mechanisms for boron cluster formation and dissolution at very high B concentrations, and the role of Si interstitials in these processes. For this purpose, high-dose, low-energy B implants and theoretical structures with fully act…
DFT Studies of the Resonance Raman Spectra of Ground and Excited Triplet State Free Base meso-Tetraphenylporphyrin (H2TPP)
DFT calculations at the B3LYP/6-31G(d) level were carried out for the ground and excited triplet states of free base meso -tetraphenylporphyrin, H 2 TPP, and its d 2, d 8, d 10, d 20, d 22, and 13 C 4 isotopomers. The agreement between experimental and calculated (scaled with a single factor of 0.973) band positions f…
Electrical properties and electric field-induced antiferroelectric–ferroelectric phase transition in Nd3+-doped lead strontium zirconate titanate ceramics
Undoped and 1–3 at. % Nd3+-doped lead strontium zirconate titanate ceramics, which were located near the tetragonal antiferroelectric (AFE) and rhombohedral ferroelectric (FE) phase boundary, were prepared by tape casting and sintering. The influence of the electric field-induced AFE to FE phase transition on the piez…
Unusual Magnetic Behavior of Six-Coordinate, Mixed-Ligand Re(II) Complexes: Origin of a Strong Temperature-Independent Paramagnetism
An explanation is presented for the unusual magnetic behavior of two Re(II) compounds, [Re(triphos)(CH 3 CN) 3 ][BF 4 ] 2 and [Et 4 N][Re(triphos)(CN) 3 ], for which magnetic susceptibility data obtained on powder samples (2−300 K) suggest unusually strong temperature-independent paramagnetism (χ TIP = (1.4−1.8) × 10…
Melt Morphology of Polystyrene−Poly(ethylene oxide) Metallo-Supramolecular Diblock Copolymer
Using SAXS, the melt morphol. of a polystyrene-poly(ethylene oxide) metallo-supramol. diblock copolymer, which is prepd. by coupling terpyridine-terminated polyethylene oxide and terpyridine-terminated polystyrene with RuCl3, is studied, and the presence of the the metal-ligand complex (MLC) in the mol. chain leads to…