A host–guest epoxidation catalyst with enhanced activity and stability
A porphyrin-capped molecular clip epoxidises olefins, depending on the axial ligand used, with enhanced activity or stability
Materials Literature
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Major hysteresis loop modeling of two-dimensional arrays of single domain particles
We have studied the effect of magnetostatic interactions on the overall shape of hysteresis loops for arrays of single domain particles. A computational model was used to calculate major hysteresis loops of arrays of particles with an easy axis along the applied field. The shear of the hysteresis loop, and consequent…
Enhanced growth rate in atomic layer epitaxy deposition of magnesium oxide thin films
Thin films of MgO were deposited by atomic layer epitaxy (ALE) from bis(cyclopentadienyl)magnesium and water using soda lime glass and Si(100) as substrates. Deposition parameters were studied in the temperature range of 100–400 °C. A plateau of surface-controlled growth was observed at 200–300 °C with a growth rate o…
Mechanical and dynamic mechanical properties of waste rubber powder/HDPE composite
Mechanical and dynamic mechanical properties of a waste rubber powder-filled high-density polyethylene (HDPE) composite are investigated. Rubber powder is surface-modified with acrylamide (AAm) using ultraviolet. Rubber powder and HDPE are extruded using a single-screw extruder and maleic anhydride-grafted polypropyle…
The flame-retardant polyester fiber: Improvement of hydrolysis resistance
As far as the flame-retardant polyester fibers are concerned, the copolymerization of phosphorus retardants is the most common method. But a serious problem is that the phosphorus-containing polymer is easily hydrolyzed. We investigated the flame retardancy and the hydrolysis properties of two poly(ethylene terephthal…
Detonation gas model for combined finite-discrete element simulation of fracture and fragmentation
The equation of state for expansion of detonation gas together with a model for gas flow through fracturing solid is proposed and implemented into the combined finite-discrete element code. The equation of state proposed enables gas pressure to be obtained in a closed form for both reversible and irreversible adiabati…
Mixed macrodiol-based siloxane polyurethanes: Effect of the comacrodiol structure on properties and morphology
Two series of polyurethanes were prepared to investigate the effect of comacrodiol structure on properties and morphology of polyurethanes based on the siloxane macrodiol, α,ω-bis(6-hydroxyethoxypropyl) polydimethylsiloxane (PDMS). All polyurethanes contained a 40 wt % hard segment derived from 4,4′-methylenediphenyl…
New soybean oil-styrene-divinylbenzene thermosetting copolymers. II. Dynamic mechanical properties
A variety of new polymeric materials ranging from soft rubbers to hard, tough, and brittle plastics were prepared from the cationic copolymerization of regular soybean oil, low saturation soybean oil (LoSatSoy oil), or conjugated LoSatSoy oil with styrene and divinylbenzene initiated by boron trifluoride diethyl ether…
Synthesis and properties of phosphorus-containing advanced epoxy resins. II
Two phosphorus-containing diacids were synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and either maleic acid or itaconic acid and then reacted with diglycidyl ether of bisphenol A (DGEBA) to form two series of advanced epoxy resins. Reaction conditions, such as reaction time, temperature an…
Analysis of double-layer capacitors supplying constant power loads
Double-layer capacitors are a recent technology based on the well-known electrochemical phenomenon of extremely high capacitance/unit area in an electrode-electrolyte interface and the high surface area achievable in activated carbon fibers. Capacitances are available in the range of a few farads to a few hundred fara…
Holographic gratings and holographic image storage via photochemical phase transitions of polymer azobenzene liquid-crystal films
Phase-type gratings formed by photochemical phase transitions of a polymer azobenzene liquid crystal have been characterized. The sensitivity of the material was improved by a factor of 23 in the liquid-crystalline phase owing to effective induction of the photochemical phase transition in the bright fringes of the in…
Accumulation of poly[(R)-3-hydroxyalkanoates] inPseudomonas oleovorans during growth in batch and chemostat culture with different carbon sources
Pseudomonas oleovorans (ATCC 29347) was grown in batch and chemostat cultures with citrate, hexanoate, heptanoate, octanoate, and nonanoate as single carbon substrates. The growth medium for batch cultures was adjusted such that nitrogen (NH(4)(+)) limitation terminated the exponential-growth phase. During batch culti…
Cytokine delivery and tissue engineering
Tissue engineering has been applied to various tissues, and particularly significant progress has been made in the areas of skin, cartilage, and bone regeneration. Inclusion of bioactive factors into the synthetic scaffolds has been suggested as one of the possible tissue engineering strategies. The growth factors are…
Enantioselective epoxidation of (Z )-stilbene using a chiral Mn(III)–salen complex: effect of immobilisation on MCM-41 on product selectivity
Manganese-exchanged Al-MCM-41 modified by the chiral salen ligand [(R,R)-(−)-N,N′-bis(3,5-di-tert-butylsalicylidene)cyclohexane-1,2-diamine] has been investigated as a heterogeneous catalyst for the enantioselective epoxidation of (Z)-stilbene using iodosylbenzene as oxygen donor, with particular interest in the effec…
Control of morphology in synthesizing mesoporous silica
Abstract Mesoporous silica can be synthesized by either the alkaline route or the acidic route, both using surfactants as templates. Morphological transformations of mesoporous silica can produce various hierarchical orders. Different morphologies are produced under different synthetic conditions. In the alkaline rout…
Strong enhancement of the lanthanide-centred luminescence in complexes with 4-alkylated 2,2′;6′,2″-terpyridines †
The stability and photophysical properties of trivalent lanthanide complexes with 2,2′;6′,2′′-terpyridines substituted in the 4 position (L1, t-butyl; L2, ethyl) have been compared to those with the unsubstituted ligand terpy. The stability constants log β3 of complexes with L1 and terpy are similar and reflect a pref…
Structural study of zinc-substituted nickel hydroxides
The structure of zinc-substituted nickel hydroxide is investigated as a function of the amount of zinc. The hydroxide shows a β-type structure with up to 10% zinc in substitution for nickel (in mol), whereas an α-type phase is stabilised with 20–50% zinc. For the β-type phases, the unit cell parameters are similar to…
Prediction of Stress Corrosion Cracking Susceptibility of Stainless Steels Based on Repassivation Kinetics
Repassivation kinetics of rapidly scratched scars on the surface of type 304 (UNS S30400) stainless steel (SS) in a chloride solution was examined using an ampero-chronometric method. Its relationship to stress corrosion cracking (SCC) susceptibility measured by slow strain rate tests (SSRT) was explored. The repassiv…
Reversible Control of the Pitch of Cholesteric Liquid Crystals by Photochromism of Chiral Fulgide Derivatives
Abstract When an enantiomer of resolved indolylfulgide (1) or either of the (R)-binaphthol-condensed indolylfulgides (2, 3) was mixed with a nematic liquid crystal (5CB), the cholesteric phase was induced. Their cholesteric pitches were reversibly changed by photoirradiation. Whereas the twisting ability of the choles…
Two-stage continuous process development for the production of medium-chain-length poly(3-hydroxyalkanoates)
Pseudomonas oleovorans forms medium-chain-length poly(3-hydroxyalkanoate) (PHA) most effectively at growth rates below the maximum specific growth rate. Under adequate conditions, PHA accumulates in inclusion bodies in cells up to levels higher than half of the cell mass, which is a time-consuming process. For PHA pro…