Materials Literature
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We study the melting behavior of a finite number ( $N\ensuremath{\le}45$) of paramagnetic colloidal spheres in a two-dimensional circular hard wall cavity. The interaction strength between the particles is varied by applying a magnetic field $B$. At high $B$, i.e., strong interaction, the particles are arranged in a h…
A rare example of a molecular species prepared by solvothermal synthesis is the macrocyclic cobalt phosphonate/carboxylate 1, whose structure is shown schematically. At low temperatures this compound displays spontaneous magnetization due to canted antiferromagnetic ordering, which is very unusual for a discrete molec…
We study the static screening in a Hubbard-like model using fixed-node diffusion Monte Carlo. We find that the random phase approximation is surprisingly accurate even for metallic systems close to the Mott transition. As a specific application we discuss the implications of the efficient screening for the superconduc…
A precision radio-frequency (RF) transverse modulation technique based on a resonant tunnel diode oscillator (TDO) has been used to study the dynamic susceptibility in novel ring-shaped single domain Fe nanoparticles synthesized using reverse-micelle chemistry. Hysteresis loops measured using a SQUID magnetometer indi…
Energetics, electronic structure, charging, and capacitive properties of bare and thiol-passivated ${\mathrm{Au}}_{38}$ gold nanocrystals were investigated via density-functional calculations. In the energy-optimized passivated nanocrystal, comprised of a truncated-octahedral face-centered-cubic ${\mathrm{Au}}_{38}$ c…
Cryptands, carcerands, polyoxometalates, and molecular capsules are cagelike hosts that complex guests through encapsulation. Following the discovery of a nanometer scale supramolecular shell-like spheroid, these and other shell-like hosts were structurally classified. Their frameworks may be catalogued according to p…
A systematic classification of the tourmaline-group minerals, general formula X Y3Z6 (T6O18) (BO3)3 V3W, is proposed, based on chemical composition and ordering at the different crystallographic sites of the tourmaline structure. There are currently thirteen accepted tourmaline species. However, based on the actual ch…
Hydrogen adsorption on crystalline ropes of carbon single-walled nanotubes (SWNT) was found to exceed 8 wt. %, which is the highest capacity of any carbon material. Hydrogen is first adsorbed on the outer surfaces of the crystalline ropes. At pressures higher than about 40 bar at 80 K, however, a phase transition occu…
Poly(ethylene glycol)-poly(L-lactide) diblock and triblock copolymers were prepared by ring-opening polymerization of L-lactide with poly(ethylene glycol) methyl ether or with poly(ethylene glycol) in the presence of stannous octoate. Molecular weight, thermal properties, and crystalline structure of block copolymers…
The syntheses and characterizations of the novel platinum(II) mono-1,2-dithiolenes (COD)Pt(dddt) ( 1 ), (Ph 3 P) 2 Pt(dddt) ( 2 ), (COD)Pt(edt) ( 3 ), (Ph 3 P) 2 Pt(edt) ( 4 ), (bipy)Pt(edt) ( 5 ), and (Ph 3 P)(CO)Pt(dddt) ( 6 ) (COD = 1,5-cyclooctadiene; dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate; edt = ethylene-1…
Whereas diphenylacetylene (DPA) exhibits no photoisomerization because of the involvement of a triple bond in the chromophore, prolonged irradiation of the films with 313-nm light resulted in the reduction of absorption, leading to insolubilization as a result of photo-cross-linking. When the actinic light is linearly…
The geometry, conformational behavior, and magnetic properties of 2-(2-imidazolyl-)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, an important spin carrier in molecular magnetic materials, have been studied by a combined experimental and theoretical approach. From the experimental point of view, the avaliable structu…
Molecular mechanics have been used to rationalize the structures of the layered double hydroxide intercalates [LiAl 2 (OH) 6 ]Cl, [LiAl 2 (OH) 6 ]Br, and [LiAl 2 (OH) 6 ]NO 3 . The simulations showed that calculated lowest energy structures were in good agreement with the experimentally determined structures and were…
The enzymatic degradation of intramolecularly polymerized methacrylated dextran [dex-poly(MA)] and hydrogels based on methacrylated dextran was studied. Dex-poly(MA) was synthesized as a soluble model compound to investigate the enzymatic degradation of dextran hydrogels. After degradation of hydrogels and dex-poly(MA…
A new precursor for the sonochemical preparation of amorphous nickel, Ni(cyclooctadiene) 2, yielded relatively large (200 nm) amorphous nanoparticles composed of nickel and carbon atoms. Small nickel particles were dispersed all over the particle. When these particles were heated slightly above their crystallization t…
Polymeric microtubules and nanofibrils have been prepared by depositing a solution of the desired polymer within the pores of microporous template membranes. Both microporous alumina and track-etched polyester membranes were used as the templates. Tubules and fibrils composed of polystyrene, poly(2,6-dimethyl-1,4-phen…
A method for solving structures from powder diffraction data was developed, and its validity was demonstrated on three complex structures. The method uses a textured sample and exploits the high intensity and parallel nature of synchrotron radiation. In principle, crystal structures as complex as those routinely solve…
Titanium-containing porous silica with a mesostructured unit as secondary pore walls has been synthesized at room temperature by a modified sol−gel method using a structure-directing agent. The transparent gel formed as a precursor resulted in high titanium incorporation in the silicate framework of up to 15 mol % Ti.…
A series of mesoporous vanadosilicate V-MCM-41 molecular sieves with variable Si/V ratios have been hydrothermally synthesized at pH = 10. These materials were investigated by powder X-ray diffraction (XRD), framework FTIR, diffuse reflectance UV−visible spectroscopy, nitrogen sorption measurement, scanning electron m…
In Escherichia coli the coenzyme pyridoxal 5'-phosphate (PLP) is synthesised de novo by a pathway that is thought to involve the condensation of 4-(phosphohydroxy)-L-threonine and 1-deoxy-D-xylulose, catalysed by the enzymes PdxA and PdxJ, to form either pyridoxine (vitamin B6) or pyridoxine 5'-phosphate (PNP). Here w…