Materials Literature
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The molecular weight averages and the degree of branching, DB, of a hyperbranched polymer obtained by self-condensing vinyl polymerization (SCVP) of a macroinimer A-(m)γ-B* is calculated by modifying the existing equations for SCVP. The polydispersity is lowered by a factor (γ + 1), where γ is the degree of polymeriza…
Titanium tin carbide (Ti2SnC) is a novel layered ternary compound. The ab initio calculations on the electronic structure and bonding properties indicated that Ti2SnC exhibit anisotropy of chemical bonding and properties. The electrical conductivity parallel to the basal plane is metallic and is much higher than that…
The time-resolved photoluminescence (PL) of luminescent porous silicon has been investigated in-situ when porous silicon is immersed in chemically inert organic solvents. PL transients are recorded upon square-wave modulation of the excitation light. They are fairly well fitted with exponential curves. The obtained li…
The use of IrOx for electrodes in PbZrxTi1−xO3 (PZT) capacitors for ferroelectric memory applications has proven to be advantageous in several respects. In comparison with Pt, IrOx often exhibits improved fatigue and provides resistance to hydrogen induced degradation at elevated temperatures. Since IrOx is often prod…
The presence of fullerene-and nanotube-like elements in carbons prepared from saccharose and anthracene by slow pyrolysis and then heat treated at 1000C, 1900C, and 2300C has been revealed using Raman spectroscopy. High energy X-ray diffraction has been used to examine the effect on these carbons of heat treatment. Te…
Hydrogen and silane desorption from n-type porous silicon samples, prepared by electrochemical etching, has been investigated by Thermal Desorption Spectroscopy (TDS). Desorption rates were monitored by a quadrupole mass spectrometer (QMS) during linear heating of the samples. Two peaks have been found in the hydrogen…
Electroconvection in twisted nematics has been studied experimentally and theoretically. The frequency dependence of the threshold voltage and rolls period for the different twist angles as well as the Lifshitz point versus the twist angle have been measured. The experimental results agree well with the predictions of…
Novel side-chain liquid-crystalline copolymers (SCLCPs) were synthesized via the Pd(II) catalyzed alternating copolymerization of mesogenic 1-alkenes and carbon monoxide. For methoxybiphenyl mesogens, these copolymers exhibited highly ordered smectic E mesophases and high glass transition temperatures. The transition…
Ultrathin Co films of thicknesses from 1 to 19 monolayers (ML) were grown on native oxide covered Si(111) surfaces near room temperature by thermal evaporations in ultrahigh vacuum. The thickness dependent total electrical sheet resistance R (Ω/□) at room temperature was measured in situ by a four-point probe. The tot…
The oxidation of porous silicon (PS) is an important issue to be considered for a better understanding of the physical and chemical properties of this material in view of its possible application in several technological fields (optoelectronics, optical filters, environmental monitoring, etc.). In this work the quick…
A core-sheath bicomponent fiber is melt-spun by co-extrusion of poly(butylene tereph thalate) (PBT) as the core and poly(butylene succinate-co-L-lactate) (PBSL) as the sheath. The resulting melt-drawn fiber is continuously guided to cold-drawing at 80°C. The core/sheath ratio of the melt-drawn fiber increases with inc…
The N-oxyl mediated donor-acceptor copolymerization of styrene as a donor and the maleimides N-phenylmaleimide (NPI), N-benzylmaleimide (BMI), and N-cyclohexylmaleimide (CMI) as acceptor monomers is studied, using 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) as reversible capping agent and benzoyl peroxide (BPO) as in…
A new one-step method is developed for the formation and separation of a thin porous silicon film (PSF) by electrochemical etching of silicon in hydrofluoric (HF) acid based solution. This provides advantages over the existing techniques, which are requiring multiple-steps for fabrication and separation of a thin laye…
We suggest a definition of the effective ionic charges q*i of different pairs of ions connected in tetrahedral, octahedral and dodecahedral polyhedra in such oxide crystals as spinels, garnets and perovskites. The electronic polarizability αi of cations and the O2— atomic core polarizability are calculated by 〈r2k〉 ac…
Fourier-type spot-array illuminators are designed for electromagnetic fields in the paraxial domain of diffractive optics. An analytical construction of the periodic, spatially variable Jones matrix is presented, which produces 100% conversion efficiency from an arbitrarily polarized incident plane wave into M × N=2 P…
Scope of Deliverables: This section describes the uses of ultrasound in the food industry. A general theory about the mechanism of microbial inactivation is presented. Data from inactivation of food microorganisms are scarce, and most applications of ultrasound involve its use in combination with other preservation me…
X-ray intensities for the “tetragonal almandine-pyrope phase” (TAPP), *(FeMg) VIII (AlMgFe) 4 [ IV (SiAl)O 4 ] 3 where * refers to a capped tetrahedral site, reported by Harris et al. (1997) were recollected using the identical crystal, and the crystal structure was refined from these new data. The basic structure of…
Silicon electrochemistry has many applications, but still a number of unanswered questions. This paper reports on experimental results of current transient measurements and impedance spectroscopy along the I–U curve in the Si–HF system. The points of inflection of the I–U characteristics are found to be interesting, s…
Inorganic siliceous porous materials such as MFI type zeolite, mesoporous silica MCM-41 and silica gel with different average pore diameters were applied to the adsorptive separation of methylaluminoxane (MAO) used as a cocatalyst in α-olefin polymerizations. The separated MAOs combined with rac-ethylene-(bisindenyl)z…
Calcined Mg-Al hydrotalcites (Mg/Al=3) can be used as an efficient catalyst in the selective O-methylation of phenol and catechol and N-monomethylation of aniline employing dimethylcarbonate (DMC) as a methylating agent in vapor phase at 275°C.