Thermoelectric Properties of Co4Sb12 Skutterudite Materials with Partial In Filling and Excess In Additions

The properties of Co4Sb12 with various In additions were studied. X-ray diffraction revealed the presence of the pure δ-phase of In0.16Co4Sb12, whereas impurity phases (γ-CoSb2 and InSb) appeared for x = 0.25, 0.40, 0.80, and 1.20. The homogeneity and morphology of the samples were observed by Seebeck microprobe and scanning electron microscopy, respectively. All the quenched ingots from which the studied samples were cut were inhomogeneous in the axial direction. The temperature dependence of the Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ) was measured from room temperature up to 673 K. The Seebeck coefficient of all In-added Co4Sb12 materials was negative. When the filler concentration increases, the Seebeck coefficient decreases. The samples with In additions above the filling limit (x = 0.22) show an even lower Seebeck coefficient due to the formation of secondary phases: InSb and CoSb2. The temperature variation of the electrical conductivity is semiconductor-like. The thermal conductivity of all the samples decreases with temperature. The central region of the In0.4Co4Sb12 ingot shows the lowest thermal conductivity, probably due to the combined effect of (a) rattling due to maximum filling and (b) the presence of a small amount of fine-dispersed secondary phases at the grain boundaries. Thus, regardless of the non-single-phase morphology, a promising ZT (S 2 σT/κ) value of 0.96 at 673 K has been obtained with an In addition above the filling limit.

Purification and partial characterization of microsomal cytochrome b555 from the higher plant Catharanthus-Roseus

Microsomal b-type hemoprotein designated, cytochrome b555 of C-Roseus seedlings was solubilized using detergents and purified by a combination of ion exchange chromatography and gel filtration to a specific content of 18.5 nmol per mg of protein. The purified cytochrome b555 was homogeneous and estimated to have an apparent molecular weight of 16500 on SDS-PAGE. The absorption spectrum of the reduced form has major peaks at 424, 525 and 555 nm. The α-band of the reduced form is asymmetric with a pronounced shoulder at 559 nm. The spectrum of the pyridine ferrohemochrome shows absorption peaks at 557, 524 and 418 nm indicating that the cytochrome has protoheme prosthetic group. The purified cytochrome is autoxidizable and does not combine with carbon monoxide, azide or cyanide. It is reducible by NADH in the presence of NADH-cytochrome b555 reductase partially purified from C-Roseus microsomes.

Differences in the Behavior of Luteinizing Hormones of Various Species at the Rat Gonadal Cell Receptor Site

The ability of different LH-like hormones, such as hCG, PMSG/equine (e) CG, ovine (o) LH, eLH, and rat (r) LH, to bind to and stimulate steroidogenesis in two types of rat gonadal cells was studied under the same experimental conditions. In both Leydig and granulosa cells, the maximal steroidogenic responses elicited by optimal doses of different LHs present during a 2-h incubation were comparable. However, if the cells were exposed to the different LHs for a brief period and then subjected to interference with hormone action by removing the unbound hormone from the medium by washing or adding specific antisera, differences were observed in the amount of steroid produced during subsequent incubation in hormone-free medium. Thus, in the case of hCG, either of these procedures carried out at 15 or 30 min of incubation had little inhibitory effect on the amount of steroid produced at 2 h, the latter being similar to that produced by cells incubated in the continued presence of hCG for 2 h. With eCG and rLH, the effect was dramatic, in that there was a total inhibition of subsequent steroidogenic response. In cells exposed to eLH and oLH, inhibition of subsequent steroidogenesis due to either removal of the free-hormone or addition of specific antisera at 15 or 30 min was only partial. Although all of the antisera used were equally effective in inhibiting the steroidogenic response to respective gonadotropins when added along with hormones at the beginning of incubation, differences were observed in the degree of inhibition of this response when the same antisera were added at later times of incubation. Thus, when antisera were added 60 min after the hormone, the inhibition of steroidogenesis was total (100%) for eCG, partial (10–40%) for eLH and oLH, and totally lacking in cells treated with hCG. From this, it appears that hCG bound to the receptor probably becomes unavailable for binding to its antibody with time, while in the case of eCG and other LHs used, the antibody can still inhibit the biological activity of the hormone. Studies with 125I-labeled hormones further supported the conclusion that hCG differs from all other LHs in being most tightly bound and, hence, least dissociable, while eCG and rLH dissociate most readily; oLH and eLH can be placed in between these hormones in the extent of their dissociability. (Endocrinology 116: 597–603,1985)

Self-assembly of three new coordination complexes: Formation of 2-D square grid, 1-D chain and tape structures

Three distinct coordination complexes, viz., [Co(imi)(2)(tmb)(2)] (1) [where imi = imidazole], {[Ni(tmb)(2)(H2O)(3)]center dot 2H(2)O}(n) (2) and [Cu-2(mu-tmb)(4)(CH3OH)(2)] (3), have been synthesized hydrothermally by the reactions of metal acetates,2,4,6-trimethylbenzoic acid (Htmb) and with or without appropriate amine. The Ni analogue of 1 and the Co analogue of 2 have also been synthesized. X-ray single-crystal diffraction suggests that complex 1 represents discrete mononuclear species and complex 2 represents a 1D chain coordination polymer in which the Ni(H) ions are connected by the bridging water molecules. Complex 3 represents a neutral dinuclear complex. In 1, the central metal ions are associated by the carboxylate moiety and imidazole ligands, whereas the central metal atom is coordinated to the carboxylate moiety and the respective solvent molecules in 2 and 3. In 3, the four 2,4,6-trimethylbenzoate moieties act as a bridge connecting two copper (11) ions and the 0 atoms of methanol coord geometry, with the methanol molecule at the apical position. In all the three structures the central metal atom sits on a crystallographic inversion centre. In all the cases, the coordination entities are further organized via hydrogen bonding interactions to generate multifarious supramolecular networks. Complexes 1, 2 and 3 have also been characterized by spectroscopic (UV/Vis and IR) and thermal analysis (TGA). In addition, the complexes were found to exhibit antimicrobial activity. The magnetic susceptibility measurements, measured from 8 to 300 K, revealed antiferromagnetic interactions between the Co(II) ions in compound 1 and the Ni(II) ions in la, respectively.

Interval Data Classification under Partial Information: A Chance-Constraint Approach

This paper presents a Chance-constraint Programming approach for constructing maximum-margin classifiers which are robust to interval-valued uncertainty in training examples. The methodology ensures that uncertain examples are classified correctly with high probability by employing chance-constraints. The main contribution of the paper is to pose the resultant optimization problem as a Second Order Cone Program by using large deviation inequalities, due to Bernstein. Apart from support and mean of the uncertain examples these Bernstein based relaxations make no further assumptions on the underlying uncertainty. Classifiers built using the proposed approach are less conservative, yield higher margins and hence are expected to generalize better than existing methods. Experimental results on synthetic and real-world datasets show that the proposed classifiers are better equipped to handle interval-valued uncertainty than state-of-the-art.