Enhancement in age hardenability of sintered Ti–5Fe alloy by Zr addition processed by pulsed electric current sintering

The age-hardenable Ti–5Fe–5Zr (wt. %, 5Zr) alloy has been consolidated by pulsed electric current sintering, following a β solution treatment, and the results are compared with a Ti–5Fe (0Zr) alloy. The precipitation sequence measured at 640°C ageing is β?+?athermal ω?→?β?+?isothermal ω?→?β?+?α. At the peak hardness isothermal ω phase forms at 20?s of ageing. The Zr addition retards the precipitation kinetics of the α phase; as a result, the α phase nucleates at latest at 300?s ageing in the overaged state. Fe is partitioned into β, while it is depleted from the α phases. There is Zr enrichment near the α/β interface when the α phase precipitates due to a solute drag effect; the growth rate of the α phase in the 5Zr alloy is significantly reduced compared with that in the 0Zr alloy.     

Concise procedure for the synthesis of cardiolipins having different fatty acid combinations

Production of a wide variety of cardiolipin (CL) analogues is critical for studying molecular mechanism of diverse biological functions of CL in mitochondria. We describe a concise procedure for the synthesis of CL using a phosphoramidite approach, which allows for the production of diverse CL analogues bearing linoleic acid(s) at any position on the glycerol backbone.     

Dynamic behaviors of ferroelectric liquid crystal molecules under an applied electric field

The dynamic changes in ferroelectric liquid crystal (FLC) molecular alignments under an applied electric field are examined by observing the formation of conoscopic figures with a time resolution of 0.1 ms. Close agreements between observed and simulated conoscopic figures under low voltage (30 V) were obtained. Under high voltage (120 V), however, the observed conoscopic figures became blurred between 0.8 ms and 1.1 ms after reversal of the electric field. The light scattering producing the blurriness occurred due to the development of fast transient molecular alignments during the switching transition above the applied voltage 70 V.     

Electron spin torque in atoms

The spin torque and zeta force, which govern spin dynamics, are studied by using monoatoms in their steady states. We find nonzero local spin torque in transition metal atoms, which is in balance with the counter torque, the zeta force. We show that d-orbital electrons have a crucial effect on these torques. Nonzero local chirality density in transition metal atoms is also found, though the electron mass has the effect to wash out nonzero chirality density. Distribution patterns of the chirality density are the same for Sc–Ni atoms, though the electron density distributions are different.     

Water-soluble constituents of dill

From the water-soluble portion of the methanol extract of dill (fruit of Anethum graveolens L.), which has been used as a spice and medicine, thirty-three compounds, including a new monoterpenoid, six new monoterpenoid glycosides, a new aromatic compound glucoside and a new alkyl glucoside were obtained. Their structures were clarified by spectral investigation.     

Evolution of magnetism in U(Ni 1- xPd x) Si single crystals

Single crystals of U(Ni_1-xPd_x)₂Si₂ with x = 0.05, 0.09 and 0.135 have been grown. Magnetization and electrical resistivity measurements were performed in a wide range of temperatures and magnetic fields in order to study stability of magnetic phases in the solid solutions between UNi₂Si₂ and UPd₂Si₂ with a special emphasis on the type of ground state. In UPd₂Si₂ the simple AFI-type antiferromagnetic structure of U moments is observed at low temperatures. UNi₂Si₂ adopts the uncompensated AF structure (UAF) with the + + - stacking of U moments along the c-axis and consequently this compound exhibits a spontaneous magnetization corresponding to 1/3 of the U moment. The substitution of Pd for Ni leads to a rapid decay of the spontaneous magnetization. The evolution of magnetization and electrical resistivity behavior with Pd doping is tentatively attributed to the coexistence of the AF-I and UAF phases in the ground state of U(Ni_0.91Pd_0.09)₂Si₂ and U(Ni_0.865Pd_0.135)₂Si₂. In this scenario, the volume fraction of the AF-I phase rapidly grows with Pd doping on account of the UAF. At lowest temperatures an irreversible transition to the UAF phase is observed when a sufficiently high magnetic field is applied along the c-axis. Received 28 March 2002 / Received in final form 8 August 2002 Published online 19 December 2002 RID="a" ID="a"e-mail: sech@mag.mff.cuni.cz     

Novel amphiphilic network polymers consisting of nonpolar,short primary polymer chains and polar,long crosslink units: Influence of characteristic dangling chains on swelling behavior of resulting amphiphilic gels

Novel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units were prepared, and the swelling behavior of resulting amphiphilic gels is discussed by focusing on the influence of characteristic dangling chains; that is, benzyl methacrylate (BzMA) was copolymerized with tricosaethylene glycol dimethacrylate [CH₂?C(CH₃)CO(OCH₂CH₂)₂₃OCOC(CH₃)?CH₂, PEGDMA‐23] in the presence of lauryl mercaptan as a chain‐transfer agent because BzMA forms nonpolar, short primary polymer chains and PEGDMA‐23 as a crosslinker contains a polar, long poly(oxyethylene) unit. The enhanced incorporation of dangling chains into the network polymer was brought by shortening the primary polymer chain length, and copolymerization with methoxytricosaethylene glycol methacrylate, a mono‐ene counterpart of PEGDMA‐23, enforced the incorporation of flexible dangling poly(oxyethylene) chains into the network polymer, although the former dangling chains as terminal parts of primary poly(BzMA) chains were rather rigid. Then, the influence of characteristic dangling chains on the swelling behavior of amphiphilic gels was examined in mixed solvents consisting of nonpolar t‐butylbenzene and polar methanol. The profiles of the solvent‐component dependencies of the swelling ratios were characteristic of amphiphilic gels. The introduction of dangling poly(oxyethylene) chains led not only to an increased swelling ratio but also to sharpened swelling behavior of amphiphilic gels. The swelling response of amphiphilic gels was checked by changing the external solvent polarity. The dangling chains with freely mobile end segments influenced the swelling response of gels. The amphiphilic gels with less entangled, collapsed crosslink units exhibited faster swelling response than the ones with more entangled, collapsed primary polymer chains. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2192–2201, 2004     

Surface photochemistry: The photo-chlorination of aromatic hydrocarbons with ferric chloride on alumina

Irradiation of a number of aromatic hydrocarbons adsorbed on alumina in the presence of ferric chloride leads to monochlorination.     

Complete asymmetric induction in heteroconjugate addition on an acyclic system a new synthetic approach directed toward ansamacrolide maytansine

Acyclic asymmetric induction was achieved in >99 % $\text{threo}$ formation via coordinated intermediate ($\text{3}$) in the heteroconjugate addition ($\text{2}$ to $\text{4}$); the heteroatom in the adduct being used for elongation of the carbon chain toward maytansine $\text{1}$).