Materials Literature
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Density--functional simulations have been performed on Na$_{55}$, Na$_{92}$ and Na$_{142}$ clusters in order to understand the experimentally observed melting properties [M. Schmidt \textit{et al.}, Nature (London) \textbf{393}, 238 (1998)]. The calculated melting temperatures are in excellent agreement with the exper…
The influence of experimental noise on densities rho(p) reconstructed by the Cormack method from their line projections, e.g. 2D ACAR spectra, is investigated. Simulations of statistical noise are performed for various sets of 2D spectra for two model rho(p) having the cubic symmetry. For the reconstructed densities p…
We describe defects - dislocations and disclinations - in the framework of Riemann-Cartan geometry. Curvature and torsion tensors are interpreted as surface densities of Frank and Burgers vectors, respectively. Equations of nonlinear elasticity theory are used to fix the coordinate system. The Lorentz gauge yields equ…
Phase transitions in CsPbCl$_3$ crystals have been explored by photoacoustic (PA) method in a wide temperature range of 150--300 K. The PA signals, induced by ns-pulsed laser excitation of electronic states and detected with a piezoelectric transducer, are thermoelastic ultrasonic waves lasting for hundreds of microse…
Three-terminal electrochemical transistors are manufactured from thin films of poly(3,4-ethylenedioxythiophene): poly(styrene sulfonic acid), and form the basis of oscillatory and digital circuits, thus opening the door for logic systems based on \(electronic paper\). The transistors use ions and electrons as signal c…
Silicon nanoparticles are synthesized from a mixture of argon/silane in a continuous flow atmospheric-pressure microdischarge reactor. Particles nucleate and grow to a few nanometers (1-3 nm) in diameter before their growth is abruptly terminated in the short residence time microreactor. Narrow size distributions are…
Novel polymer core–shell nanoparticles that exhibited a pH-dependent lower critical solution temperature (LCST) have been synthesized. The nanoparticles displayed stable structure in a nominal physiological environment but deformed and precipitated in an acidic environment, thereby releasing the enclosed drug molecule…
We have developed a unique micromechanical method to extract extremely thin graphite samples. Graphite crystallites with thicknesses ranging from 10 to 100nm and lateral size ∼2μm are extracted from bulk. Mesoscopic graphite devices are fabricated from these samples for electric field-dependent conductance measurement…
We report the immobilization of various enzymes in mesoporous silica (MS) spheres followed by encapsulation via the layer-by-layer assembly of multilayered nanocomposite thin shells. A range of enzymes with different molecular sizes and isoelectric points (pI) (e.g., catalase, peroxidase, cytochrome C, and lysozyme) h…
Fe/Ti oxide films with graded composition profiles have been prepared from aqueous metal‐fluoro complex solutions by the liquid phase deposition method. Films were deposited from a solution, in which the (NH 4 ) 2 TiF 6 solution was added under a controlled flow rate into the FeOOH–NH 4 F·HF solution. Transmission ele…
We report the results of a study of the growth of pores in n-CdSe single crystals using anodic etching techniques. Upon anodization in dark, a nonuniform distribution of pores was produced. However, anodic dissolution of the material under in situ UV illumination proves to result in uniform distribution of pores stret…
2,3-Anhydroerythritol ( 1a ) and 2,3-anhydro- dl -threitol ( 1b ) were polymerized using boron trifluoride diethyl etherate (BF 3 ·OEt 2 ) as a cationic initiator. The polymerizations of 1a and 1b proceeded through a ring-opening reaction with a proton-transfer reaction to produce hyperbranched carbohydrate polymers (…
An integral equation theory is developed for the structure and thermodynamics of melts of random copolymers. The molecules are modeled as flexible chains with a random sequence of two types of sites, with square well potentials between sites. The polymer reference interaction site model (PRISM) integral equation theor…
Recent experiments indicated that the formation of small, nonstoichiometric clusters Zn(n)S(m) and Zn(n)S(m)+ was possible. In this work, the ground states of these clusters, where 1 < or = n, m < or = 4, were studied using density functional theory. Global minima were found to be primarily cyclic structures in which…
Abstract The structural evolution during uniaxial stretching of poly(vinyl chloride) films was studied using our real time spectral birefringence stretching machine. The effect of clay loading and the amount of plasticizer as well as the rate effects on the birefringence development and true mechanical response are pr…
Syndiotactic polystyrene (sPS) is a semicrystalline polymer for which several crystalline structures can be obtained. Cold crystallization of an amorphous sPS sample results in the formation of the α-phase, for which a close packing of the chains is hindered by the phenyl rings. This results in the unusual situation t…
The precursor phases of ${\mathrm{SrFeO}}_{3\ensuremath{-}x}$ (SFO) and ${\mathrm{SrMoO}}_{4}$ (SMO) were used to prepare ${\mathrm{Sr}}_{2}{\mathrm{FeMoO}}_{6}$ with different ratios by a solid-state reaction technique. An x-ray diffractometer was used to identify the phases. SMO was observed to exist in the Mo-rich…
Several synthesis strategies used to obtain hydrothermally stable and highly active catalysts based on ordered mesoporous materials are reviewed in this contribution. It is experimentally observed that the use of zeolite precursors as building blocks of the mesoporous network yields the most stable materials. However,…
A new polyoxovanadate species formulated [V 16 O 42 ] 4– was isolated in DMF solvent. Its structure was solved at 100 K by single-crystal X-ray diffraction in the centrosymmetric monoclinic C 2/ c (no. 15) space group with lattice parameters a = 25.554(6) Å, b = 14.227(3) Å, c = 28.485(6) Å, β = 113.21(1)°, V = 9518(4…
The topology of crack tips in soda–lime–silicate glass was investigated using atomic force microscopy (AFM). Studies were conducted on cracks that were first propagated in water and then subjected to stress intensity factors either at or below the crack growth threshold. Exposure to loads at the crack growth threshold…