Influence of Li2O on the carbonate capacity of CaO- CaFv2- AI2O3 Melts

The influence of Li₂O on the carbonate capacity of CaO-CaF₂-Al₂O₃-based fluxes is examined by a thermogravimetric technique over the temperature range 1250 °C to 1350 °C. The values of the carbonate capacities (Cc = wt pct CO₂/P_CO2) were calculated by the solubility and the partial pressure of carbon dioxide. The replacement of CaO by Li₂O resulted in a decrease of the carbonate capacity. The addition of Li₂O, from 0.4 to 2.0 pct, to the CaO-CaF₂-Al₂O₃ increases the carbonate capacity at 1300 °C by 50 pct. At 0.4 pct Li₂O,Cc is 1.2, and at 2.1 pct Li₂O,Cc is 2.1. The replacement of CaF₂ by Al₂O₃ was found to have no significant influence on the carbonate capacity of the investigated ternary system. SIMEON SIMEONOV, formerly Visiting Research Fellow, Institute of Industrial Science, University of Tokyo. KOJI FUKTTA, formerly with the Institute of Industrial Science, University of Tokyo.     

Reactions of a bituminous coal with metal chlorides in carbon tetrachloride

The interaction of a bituminous coal (87.2% C) with several metal chlorides in carbon tetrachloride was studied using the conditions under which graphite forms intercalation compounds. Adducts with SbCl₅, AlCl₃, FeCl₃ and MoCl₅ were isolated by filtration and washing with carbon tetrachloride. Atomic ratios versus coal carbon are as follows: C_10.0SbCl_7.4; C_6.2AlCl_4.1; C_6.3FeCl_3.3; and C_11.3MoCl_3.8. X-ray diffraction patterns of the adducts show no 002-band, the latter being partially recovered after extraction with diluted hydrochloric acid. The g-value of the e.s.r. signal of the coal vitrain shows a characteristic increase because of adduct formation with SbCl₅ and AlCl₃ and is reversible by hydrolysis extraction. The results obtained indicate that the bonding with SbCl₅ and AlCl₃ is mainly due to formation of chloro-complexes and with FeCl₃ and MoCl₅ — to formation of organo-metal complexes.     

Influence of Li2O Doping on Non-Isothermal Evolution of Phases in K–Na-Containing Aluminosilicate Matrix

The phase transformations in Li₂O-doped model formulations (using 1–7% Li₂CO₃), which comprised 50% kaolin, 25% feldspar, and 25% quartz (in wt%), were investigated experimentally and with the aid of thermodynamic calculations between 900° and 1350°C. Experimental and theoretical approaches agree fairly well with another and indicated that the presence of Li₂O and other alkalis, such as K₂O, in aluminosilicate matrices plays an important role in the phase transformations that occur at different temperatures during firing. Discrepancies in experimental results from thermodynamics have been attributed to slow kinetics, also likely because of the nature of the raw materials used.     

Metabolic studies in isolated rat liver cells: I. Lipid synthesis

Rat liver cells, isolated by chelate perfusion and extrusion through a tissue press, incorporated labeled acetate into cellular lipids and into lipids released into the suspending medium. Optimal rates of incorporation required supplementation of tris-KCl medium with Mg⁺⁺, Mn⁺⁺, succinate, citrate, nicotinamide, Coenzyme A, NADP and glucose-6-phosphate. The rate of acetate incorporation was markedly altered by changes in incubation media; tris-KCl was the most effective buffer. All the major classes of cellular lipids were labeled. ATP, BSA, inorganic phosphate, Ca⁺⁺, 2,4-dinitrophenol and sodium clofibrate were potent inhibitors of acetate incorporation. When added to the incubation mixture, several hormones altered the rate of acetate incorporation into lipids.     

Phospholipid studies of marine organisms: V1 new α-methoxy acids fromHigginsia tethyoides

The phospholipids of the demospongeHigginsia tethyoides are shown to have at least 16 long-chain α-methoxy acids, which represent a new class of fatty acids. Among them are the saturated α-methoxy acids containing 19–24 carbon atoms. The monounsaturated compounds are 2-OMe-Δ¹⁷-24:1, 2-OMe-Δ¹⁸-25:1, 2-OMeΔ¹⁹-26:1 and 2-OMe-Δ²¹-28:1. The major diunsatured ones were shown to be 2-OMe-Δ^{5, 19}-26:2 and 2-OMe-Δ^{7, 21}-28:2. Small amounts of 2-OMe-23∶1, 2-OMe-26∶3; 2-OMe-27∶1 and 2-OMe-28∶3 were also encountered. Structures of the minor monounsaturated compounds were tentatively assigned as 2-methoxy-16-tricosenoic acid and 2-methoxy-20-heptacosenoic acids. The double bonds of the fatty acids show all-cis configuration. Circular dichroism measurements indicate an R-configuration for the α-methoxy acids. The major component of the total phospholipid acid mixture is 5,9,23-triacontatrienoic acid. Possible biosynthetic routes to these unusual phospholipid acids are discussed. The major phospholipids were phosphatidylethanolamine, phosphatidylglycerol and phosphatidylserine. The distribution of fatty acids among the phospholipids was also investigated.     

Stimulation of bile acid synthesis by dibutyryl cyclic AMP in isolated rat hepatocytes

Freshly isolated rat hepatocytes were used to examine the effects of dibutyryl cyclic AMP on the incorporation of¹⁴C-acetate and¹⁴C-cholesterol into bile acids. After an initial lag period, both precursors were incorporated into cholic and chenodeoxycholic acids at a linear rate for the subsequent 60 min. An apparent stimulation of bile acid formation from¹⁴C-acetate by dibutyryl cyclic AMP was complicated by the concomitant inhibition of cholesterol synthesis. In experiments with¹⁴C-cholesterol, dibutyryl cyclic AMP (1 mM) increased the labeled cholic and chenodeoxycholic acids in the medium by 83 and 224%, respectively, but cellular levels of labeled bile acids were unchanged. As a result, the nucleotide stimulated the overall incorporation of¹⁴C-cholesterol into cholic acid by 39% and into chenodeoxycholic acid by 123%. The mean ratio of labeled cholic to chenodeoxycholic acid declined from 55∶45 in control cells to 41∶59 in cells incubated with dibutyryl cyclic AMP. The results demonstrate that label incorporation can be used to study the regulation of bile acid synthesis in isolated hepatocytes. We propose that dibutyryl cyclic AMP enhances bile acid production by phosphorylating, and thus stimulating the activity of, cholesterol 7α-hydroxylase, the rate-limiting enzyme in bile acid synthesis.     

What makes virtual agents believable?

In this paper we investigate the concept of believability and make an attempt to isolate individual characteristics (features) that contribute to making virtual characters believable. As the result of this investigation we have produced a formalisation of believability and based on this formalisation built a computational framework focused on simulation of believable virtual agents that possess the identified features. In order to test whether the identified features are, in fact, responsible for agents being perceived as more believable, we have conducted a user study. In this study we tested user reactions towards the virtual characters that were created for a simulation of aboriginal inhabitants of a particular area of Sydney, Australia in 1770 A.D. The participants of our user study were exposed to short simulated scenes, in which virtual agents performed some behaviour in two different ways (while possessing a certain aspect of believability vs. not possessing it). The results of the study indicate that virtual agents that appear resource bounded, are aware of their environment, own interaction capabilities and their state in the world, agents that can adapt to changes in the environment and exist in correct social context are those that are being perceived as more believable. Further in the paper we discuss these and other believability features and provide a quantitative analysis of the level of contribution for each such feature to the overall perceived believability of a virtual agent.     

An experimental and numerical analysis of the influence of the inlet temperature,equivalence ratio and compression ratio on the HCCI auto-ignition process of Primary Reference Fuels in an engine

In order to understand better the auto-ignition process in an HCCI engine, the influence of some important parameters on the auto-ignition is investigated. The inlet temperature, the equivalence ratio and the compression ratio were varied and their influence on the pressure, the heat release and the ignition delays were measured. The inlet temperature was changed from 25 to 70 °C and the equivalence ratio from 0.18 to 0.41, while the compression ratio varied from 6 to 13.5. The fuels that were investigated were PRF40 and n-heptane. These three parameters appeared to decrease the ignition delays, with the inlet temperature having the least influence and the compression ratio the most. A previously experimentally validated reduced surrogate mechanism, for mixtures of n-heptane, iso-octane and toluene, has been used to explain observations of the auto-ignition process. The same kinetic mechanism is used to better understand the underlying chemical and physical phenomena that make the influence of a certain parameter change according to the operating conditions. This can be useful for the control of the auto-ignition process in an HCCI engine.     

On partitioning rectilinear polygons into star-shaped polygons

We present an algorithm for finding optimum partitions of simple monotone rectilinear polygons into star-shaped polygons. The algorithm may introduce Steiner points and its time complexity isO(n), wheren is the number of vertices in the polygon. We then use this algorithm to obtain anO(n logn) approximation algorithm for partitioning simple rectilinear polygons into star-shaped polygons with the size of the partition being at most six times the optimum.     

Teaching the theory of estimation and detection via a GSM radio interface Simulation

A new way to teach advanced undergraduate and graduate students the theory of estimation and detection is described. The paper shows that the global system mobile (GSM) radio interface is well suited to the teaching of estimation and detection theory because it entails the understanding and application of several concepts within estimation and detection, as well as information theory, signal processing, and radio-wave propagation. With GSM now a mature system with specifications available in the public domain, the students created an open-source (OS) GSM simulator, including all four modulation and coding schemes (MCS 1,2,3,4) with puncturing, a channel estimator, a minimum phase prefilter, a Max log maximum a posteriori probability (MAP) equalizer, and a convolutional decoder. Studying and understanding the theory of estimation and detection is now possible by creating algorithms for the simulator and evaluating the impact of the algorithm on the GSM block error rate (BLER). Several experiments that are possible with the simulator are described.