China Science

This study focused on an investigation of a high drug-loaded solid dispersion system consisting of drug, carrier,; surfactant. Solid dispersions of a water-insoluble ofloxacin (OFX) with polyethylene glycol (PEG) of different molecular weights, namely binary solid dispersion systems, were prepared at drug to carrier not less than 5?5. Polysorbate 80, a nonionic surfactant, was incorporated into the binary solid dispersion systems as the third component to obtain the ternary solid dispersion systems. The powder x-ray diffraction; differential scanning calorimetric studies indicated that crystalline OFX existed in the solid dispersions with high drug loading. However, a decreased crystallinity of the solid dispersions obtained revealed that a portion of OFX was in an amorphous state. The results indicated a remarkably improved dissolution of drug from the ternary solid dispersion systems when compared with the binary solid dispersion systems. This was because of polysorbate 80, which improved wettability; solubilized the non-molecularly dispersed or crystalline fraction of OFX.

Siriporn Okonogi1Email:sirioko@chiangmai.ac.th?Satit Puttipipatkhachorn2
[1] Faculty of Pharmacy, Dept. of Pharmaceutical Sciences, Chiang Mai University, 50200 Chiang Mai, Thailand ;[2] Faculty of Pharmacy, Dept. of Manufacturing Pharmacy, Mahidol University, 10400 Bangkok, Thailand

Macroscopic deformation modes, elastic, uniform plastic, and unstable plastic deformation modes, are mapped in tensile true stress–dose space for more than two dozen metallic materials consisting of 13 body-centered cubic (bcc), 11 face-centered cubic (fcc), and two hexagonal closed packed (hcp) metals. The boundaries between different deformation zones are set by the true stress versus dose curves: the yield stress (YS), plastic instability stress (PIS), and true fracture stress (FS) plotted as functions of dose. Values for these true stresses are obtained from uniaxial tensile tests or calculated from engineering tensile data using a linear strain-hardening model for necking deformation. The relatively low-strength annealed fcc metals display large uniform plasticity regions, while unstable deformation regions are dominant in the harder bcc and hcp metals. PIS values for all materials are independent of dose except for the precipitation-hardened IN718 alloy, where a decrease of PIS occurs due to an irradiation-induced change in second phases. In the bcc materials for high-temperature application, such as 9Cr ferritic/martensitic steels, sintered molybdenum, vanadium, and tantalum, the radiation-induced embrittlement is characterized in terms of FS decreasing with dose at relatively high doses. FS is nearly dose-independent below the critical dose for embrittlement. It is concluded that the tensile stress-based deformation mode maps effectively integrate mechanical property information and characterize differences in radiation effects between crystalline structures or material groups.

Thak Sang ByunaEmail:byunts@ornl.gov?Kenneth Farrella?Meimei Lia
[a]Oak Ridge National Laboratory, P.O. Box 2008, MS-6151, Oak Ridge, TN 37831, USA

The direct synthesis of Li[BH4] and Li[B11D4] from the corresponding elements at T = 700 °C and p(H2) (or p(D2)) = 150 bar is demonstrated. The chemical inertness of boron is thought to prevent its reaction with lithium and hydrogen to LiBH4 at lower temperatures. We show, however, that the reaction kinetics can be enforced by a LiB3-like alloy and a Li7B6 intermetallic compound, which are formed in inert argon atmosphere at 330 and 450 °C, respectively. The synthesis is performed by exposing the Li–B mixtures to a defined hydrogen pressure in a high pressure stainless steel vessel and the hydrogen adsorption is monitored by the pressure decrease. The product is identified by X-ray powder diffraction.

O. FriedrichsaEmail:oliver.friedrichs@empa.ch?F. Buchtera?A. Borgschultea?A. Remhofa?C.N. Zwickyb?Ph. Maurona?M. Bielmanna?A. Züttela
[a]Division of Hydrogen and Energy, EMPA Materials Sciences and Technology, Department of Environment, Energy and Mobility, überlandstrasse 129, CH-8600 Dübendorf, Switzerland;[b]Division of Solid State Chemistry and Catalysis, EMPA Materials Sciences and Technology, Department of Environment, Energy and Mobility, überlandstrasse 129, CH-8600 Dübendorf, Switzerland

The cyclic plastic response of a single crystalline thin beam subject to combined cyclic tension and bending is analyzed using two-dimensional discrete dislocation plasticity. In this contribution, special attention is paid to the difference in the inherent mechanism of the size effect for different cyclic loads. Results show that the cyclic plastic response has a strong size effect for both cyclic pure tension–compression and pure bending. However, the inherent mechanisms are different. The dislocation starvation mechanism dominates the cyclic tension–compression while the geometrically necessary dislocation dominates the cyclic pure bending. When the combined cyclic tension and bending are applied to the thin beam, the cyclic moment–rotation response shows strong size effect while the stress–strain response shows weak or even no size effect. In addition, it is also found that the cyclic loading paths have considerable influences on the shape of the cyclic stress–strain loops

Chuantao Houa?Zhenhuan Li aEmail:zhli68@263.net?Minsheng Huanga?Chaojun Ouyanga
[a]Department of Mechanics, Huazhong University of Science; Technology, 1037 Luoyu Road, Wuhan 430074, China

Dehydriding and rehydriding properties of well-crystallized Mg(BH4)2 were systematically investigated by thermogravimetry (TG) and pressure–composition–temperature (PCT) measurements. The dehydriding reaction of Mg(BH4)2starts at approximately 500 K, and about 14.4 mass% of hydrogen is desorbed according to the following multi-step reaction:Mg(BH4)2 ? some intermediate compounds ? MgH2 + 2B + 3H2 ? Mg + 2B + 4H2The apparent enthalpy change in the dehydriding reaction from Mg(BH4)2 to MgH2 is estimated to be 57 ± 5 kJ mol?1 H2 based on the result of the PCT measurement. It is proved that approximately 6.1 mass% of hydrogen can be reversibly stored for the sample of Mg(BH4)2 after the dehydriding reaction, through the formation of a possible intermediate compound such as MgB12H12.

H.-W. Lia?K. Kikuchia?Y. Nakamoria?N. Ohbab?K. Miwab?S. Towatab?S. OrimoaEmail:orimo@imr.tohoku.ac.jp
[a]Institute for Materials Research, Tohoku University, Sendai 980–8577, Japan;[b]Toyota Central R&D Laboratories, Inc., Nagakute, Aichi 480–1192, Japan

Radical pairs, polarons and fullerene anion-radicals, photoinduced by laser with photon energies of 1.88, 2.22 and 2.75 eV in the poly(3-dodecylthiophene)/[6,6]-phenyl-C61-butanoic acid methyl ester (P3DDT/PCBM) bulk heterojunction, were studied over a wide temperature range. The number of these centers was found to decrease with the increase in laser photon energy. Both the spin–lattice and spin–spin relaxation times of fullerene anion-radicals and the spin–spin relaxation time of polarons change monotonically with temperature, whereas the interaction of polarons with the lattice is characterized by extreme temperature dependence. The one-dimensional polaron diffusion along the polymer chain and the rotation of fullerene near it own main axis was shown to follow the activation Elliot hopping model and to be governed by the photon energy. The deviation in activation energies for polaron and anion-radical motion and the difference in their dependence on the laser photon energy prove the non-interacting character of these charge carriers photoinduced in the P3DDT/PCBM bulk heterojunction.

V.I. KrinichnyiaEmail:kivi@cat.icp.ac.ru
[a]Institute of Problems of Chemical Physics RAS, N.N. Semenov Avenue 1, Chernogolovka 142432, Russia

Cretaceous-Paleogene overpressure distribution in the Danish Central Graben shows a remarkable coincidence with the thickness of the rapidly deposited middle Miocene to Holocene succession.Slow deposition of smectite-dominated clays in a deep-marine environment occurred from the late Paleocene until the middle Miocene,and the resultant mudstone succession constitutes the main barrier that delays pressure dissipation.Between the late Miocene and the Holocene,the Upper Cretaceous-Paleogene succession became over-pressured,probably because of accelerated depositional rates.Quantification of this disequilibrium compaction mechanism relies mainly on a determination of permeability and effective compressibility of the Paleogene shales.This article shows that realistic permeabilities can be assumed,provided that compressibilities describing the plastic process of compaction are used in the pressure equation instead of the elastic compressibilites that,for instance,can be derived from log data.One-dimensional(1-D)modeling is applied in two cases:a well from the Dan chalk field,where accelerated deposition since the Tortonian(11.2 Ma)produced a present-day overpressure of 7.97 MPa(1156 psi);and a well from the South Arne chalk field,where accelerated deposition since the early Serravallian(14.6 Ma)produced a present-day overpressure of 13.9 MPa(2016 psi).This is based on an identical set of parameters and compares with the observed 7.7 and 14.8 MPa(1117 and 2147 psi)overpressure at the two locations.The modeled development of the pressure profiles shows that an effective stress minimum occurred in the upper part of the Paleogene succession.This is consistent with the observed ubiquitous intraformational faulting at that level.About 80% of the added Neogene load is estimated to have been converted to overpressure.

Ole Valdemar Vejbaek

Tennessee anthropologist William M. Bass III (right) helps catch killers through the study of decomposing bodies. At his research facility near Knoxville, known as the Body Farm, as many as 40 bodies at a time lie decomposing. The research helps experts determine murder victims’ time of death.