Al2O3─SiC Composites from Aluminosilicate Precursors

Al₂O₃ and SiC composite materials have been produced from mixtures of aluminosilicates (both natural minerals and synthetic) and carbon as precursor materials. These composites are produced by heating a mixture of kaolinite (or synthetic aluminosilicates) and carbon in stoichiometric proportion above 1550°C, so that only Al₂O₃ and SiC remain as the major phases. A similar process has also been used for synthesizing other composite powders having mixtures of Al₂O₃, SiC, TiC, and ZrO₂ in different proportions (all compounds together or selective mixtures of some of them), as desired. The microstructure of hot-pressed dense compacts, produced from these powders, revealed that the SiC phase is distributed very homogeneously, even occasionally within Al₂O₃ grains on a nanosize scale. The homogeneous distribution of SiC particles within the system produced high fracture toughness of the hot-pressed material (K_IC∼ 7.0 MPa · m^1/2) and having Vicker's hardness values greater than 2000 kgf/mm².     

Electrophoretic deposition of carbon nanotubes

Electrophoretic deposition (EPD) has been gaining increasing interest as an economical and versatile processing technique for the production of novel coatings or films of carbon nanotubes (CNTs) on conductive substrates. The purpose of the paper is to present an up-to-date comprehensive overview of current research progress in the field of EPD of CNTs. The paper specifically reviews the preparation and characterisation of stable CNT suspensions, and the mechanism of the EPD process; it includes discussion of pure CNT coatings and CNT/nanoparticle composite films. A complete discussion of the EPD parameters is presented, including electrode materials, deposition time, electrode separation, deposition voltage and resultant electric field. The paper highlights potential applications of the resulting CNT and CNT/composite structures, in areas such as field emission devices, fuel cells, and supercapacitors.     

Secretion and secretory tissues of the anal sac of the mink,Mustela vison

The sulfur-rich anal sac secretion of the mink,Mustela vison, consisted of immiscible lipid (1.7% sulfur) and aqueous (0.7% sulfur) phases. Light and electron microscopy revealed secretory tissue of two types, sebaceous (holocrine) and apocrine. A major input of sulfur into the sac appeared to be associated with glycoprotein granules present in the apical portions of the apocrine cells as X-ray energy probe microanalysis showed these to contain relatively high levels of sulfur. The lipid of the secretion, presumed to be largely of sebaceous origin, consisted mainly of wax monoesters, while the aqueous phase contained volatile fatty acids, ammonia, and amines, including putrescine (1,4-diaminobutane). The identity of the major headspace volatiles was confirmed by NMR, MS, and Raney nickel desulfuration as being 2,2-dimethylthiacyclobutane and 3,3-dimethyl-1, 2-dithiacyclopentane. These compounds were not detected by GC-MS in the headspace volatiles of the anal sac secretions of eight other mustelid species examined. Other sulfur compounds detected included isomeric dimethylthiacyclobutanes, a number of disulfides and 3-methyl-but-3-enyl methyl sulfide (isopentenyl methyl sulfide). The significance of these findings is discussed.     

Optimizing BRDF orientations for the manipulation of anisotropic highlights

This paper introduces a system for the direct editing of highlights produced by anisotropic BRDFs, which we call anisotropic highlights. We first provide a comprehensive analysis of the link between the direction of anisotropy and the shape of highlight curves for arbitrary object surfaces. The gained insights provide the required ingredients to infer BRDF orientations from a prescribed highlight tangent field. This amounts to a non‐linear optimization problem, which is solved at interactive framerates during manipulation. Taking inspiration from sculpting software, we provide tools that give the impression of manipulating highlight curves while actually modifying their tangents. Our solver produces desired highlight shapes for a host of lighting environments and anisotropic BRDFs.     

Fuzzy logical control based on optical information technologies

This paper is concerned with one problem in creating intellectual control systems: methods and design tools of fuzzy logical devices for building modern efficient and reliable control systems in poorly formalized problems and ill-structured problem domains. Flaws of the available microprocessor devices for fuzzy information processing are indicated and alternative design principles of fuzzy logic control systems based on high-speed spatially distributed wave guide optical structures are considered based on an example of an opto-electronic dephaser. High-speed spatially distributed wave guide optical structures are shown as being advantageous for solving the scientific and engineering problems for developing new design methods of fuzzy logical devices with enhanced technical characteristics for implementation of fuzzy logical control.     

Investigation of Taimyrsk graphites for producing periclase-carbon ladle refractories

Conclusions The investigations showed that Taimyrsk graphite corresponds in chemical composition to foundry and crucible graphite.The content of crystalline graphite equals 13.0–26.3%. The characteristics of periclase carbon goods based on foundry and Taimyrsk graphites correspond to the demands placed on ladle refractories. The wear factors of these products in the slag belt of the lining of 350-tonne steel ladles are on practically the same level.Taimyrsk graphites may be used for the production of periclase-carbon ladle refractories in place of crucible or foundry graphite.L. N. Kurlyandskaya (Urals Geology Planning Association) and L. Ya. Osipova (All-Union Institute of Refractories) took part in this research.Translated from Ogneupory, No. 1, pp. 15–17, January, 1991.     

The metabolism of 1-acyl-PAF in rabbit platelets and its possible interaction with PAF

The metabolism of 1-acyl-2-acetyl-sn-glycero-3-phosphocholine (1-acyl-PAF), a naturally occurring analogue of platelet activating factor (PAF), was investigated in rabbit platelets. Our studies showed that 1-acyl-[³H]PAF (1-palmitoyl-2-acetyl-sn-glycero-3-phospho[N-methyl-³H]-choline) was converted by platelets into phosphatidyl-[³H]choline ([³H]PC) in a time-dependent fashion. The formation of [³H]PC occurred at a rate similar to that observed when lyso-[³H]PC (palmitoyl-sn-glycero-3-phospho[N-methyl-³H]choline) was used as substrate. In addition, a time-dependent increase in the level of water-soluble radioactivity was observed during the incubation of platelets with either 1-acyl-[³H]PAF or lyso-[³H]PC. This increase was parallel to the formation of [³H]PC and was not observed in the presence of [¹⁴C]PAF (1-octadecyl-2-acetyl-sn-glycerol-3-phospho[N methyl-¹⁴C]choline). Analysis by thin-layer chromatography showed that the soluble radioactivity was mainly associated with glycerophosphocholine (GPC). On the other hand, the preincubation of platelets with phenylmethylsulfonyl fluoride, an inhibitor of the acetylhydrolase, reduced the hydrolysis of 1-acyl-[³H]PAF to [³H]GPC with a concomitant accumulation of radioactivity in 1-acyl-PAF. These findings suggest that 1-acyl-PAF is converted into PC through deacetylation-reacylation with lysoPC as an obligatory intermediate. The findings also indicate that the lysoPC resulting from 1-acyl-PAF is either reacylated to phosphatidylcholine (PC) or hydrolyzed to GPC by lysophospholipase. Finally, we showed that the stimulation of platelets with PAF led to a time- and concentration-dependent increase in the conversion of 1-acyl-[³H]PAF to [³H]PC. The stimulatory effect of PAF was not observed when platelets were lysed before incubation, suggesting that PAF enhances the metabolism of 1-acyl-PAF, probably by accelerating its translocation through the plasma membrane.     

Flow-based reputation with uncertainty: evidence-based subjective logic

The concept of reputation is widely used as a measure of trustworthiness based on ratings from members in a community. The adoption of reputation systems, however, relies on their ability to capture the actual trustworthiness of a target. Several reputation models for aggregating trust information have been proposed in the literature. The choice of model has an impact on the reliability of the aggregated trust information as well as on the procedure used to compute reputations. Two prominent models are flow-based reputation (e.g., EigenTrust, PageRank) and subjective logic-based reputation. Flow-based models provide an automated method to aggregate trust information, but they are not able to express the level of uncertainty in the information. In contrast, subjective logic extends probabilistic models with an explicit notion of uncertainty, but the calculation of reputation depends on the structure of the trust network and often requires information to be discarded. These are severe drawbacks. In this work, we observe that the ‘opinion discounting’ operation in subjective logic has a number of basic problems. We resolve these problems by providing a new discounting operator that describes the flow of evidence from one party to another. The adoption of our discounting rule results in a consistent subjective logic algebra that is entirely based on the handling of evidence. We show that the new algebra enables the construction of an automated reputation assessment procedure for arbitrary trust networks, where the calculation no longer depends on the structure of the network, and does not need to throw away any information. Thus, we obtain the best of both worlds: flow-based reputation and consistent handling of uncertainties.