Mass-Spectrometric and Electrochemical Studies of Thermodynamic Properties of Liquid and Solid Phases in the System CaO-Al2O3

The activities of CaO and Al₂O₃ in lime-alumina melts were studied by Knudsen cell-mass spectrometry at 2060 K. Emf of solid state cells, with CaF₂ as the electrolyte, was measured from 923 to 1223 K to obtain the free energies of formation of the interoxide compounds. The results are critically evaluated in the light of data reported in the literature on phase equilibria, activities in melts, and stabilities of compounds. A coherent set of data is presented, including the previously unknown free energy of formation of CaO.6Al₂O₃ and the temperature dependence of activities in the liquid phase.     

On the bounds of the trajectories of differential systems†

The behaviour of differential systems is investigated by considering the stability and instability of such systems with respect to certain sub-sets of the state space These Sets may in general be time-varying, and their properties do not only yield information about the stability of a system but also estimates of the bounds of the system trajectories. In all cases the results which are established yield sufficient conditions for stability and instability, and in general involve the existence of Lyapunov-like functions which do not appear to possess the usual definiteness requirements on V and [Vdot].

The developed theory is applied to two special cases: in one case, only time-invariant sub-sets are considered: in the second case, the time interval [t₀, ∞) over which the systems me defined is truncated to [t ₀, t _a  + T), T < ∞, So the that case of stability over a finite time interval may be considered.     

不同电解质溶液及其离子浓度和pH值对改性微滤膜流动电势的影响(英文)

采用商品级α-Al2O3微滤膜.由均质共沉淀法制备了TiO2改性α-Al2O3微滤膜.研究了不同的电解质溶液、溶液的离子浓度和pH值对TiO2 改性的α-Al2O3微滤膜流动电势的影响规律.结果表明:对于NaCl溶液,膜流动电势随溶液离子浓度的增大向降低,其等电点在4.3左右:随着溶液的pH值由3增加到10.膜流动电势由值逐渐变为负值.而对于FeSO4,CaSO4,Na2SO4,NaCl和CaCl2溶液,当溶液的离子浓度固定时,膜流动 电势则随溶液的电导率的增加而降低.     

Stability,transient behaviour and trajectory bounds of interconnected systems†

In practice, many systems are complex and of high dimension. Many such systems may be viewed as being composed of several simpler sub-systems which when connected in an appropriate fashion yield the original composite system. The stability, the transient behaviour and estimates for the trajectory bounds of certain composite systems are analysed in terms of their sub-systems. This is accomplished by defining the stability of sub-systems and of composite systems in terms of certain time-varying sub-sets of the state space which are pre-specified in a given problem.

After stating definitions of stability for sub-systems which are under the influence of perturbing forces and for composite systems, theorems are stated and proved which yield sufficient conditions for stability. These theorems involve the existence of Lyapunov-like functions which do not possess any particular definiteness requirements on V and [Vdot].

The time-varying sub-sets of the state space which are utilized in the stability definitions and which arise in conjunction with the stability theorems yield estimates of the transient behaviour and of the trajectory bounds of both sub-systems and composite systems.

To demonstrate the generality of the developed theory, several special cases are considered. Also, some specific examples are worked out to demonstrate the methods involved.     

Cooperative research in underwater robot mission-level programming methodologies

Programming autonomous vehicles to accomplish complex missions is a complicated task for which the development of control architectures is of prime importance. The goal of this paper is to describe the accomplishments of both French and American teams within a cooperative research program focused on the development of high-level control of semi-autonomous underwater vehicles. In particular, two different mission-programming methodologies are examined in the context of the requirements of a generic, reactive and complex underwater mission. The French team uses a combination of the ESTEREL synchronous programming language and the PIRRAT real-time control library to implement a methodology derived from the ORCCAD programming system. The approach taken by the American team builds a trilevel hybrid architecture using the CONTROLSHELL real-time software development environment. The details of each methodology are highlighted through the presentation of the high-level programs designed by each team using their approach to control an underwater robot to perform a multiphased underwater mission. The utility of both programming methodologies was verified through the successful completion of those missions in experimental demonstrations by the French VORTEX and American OTTER autonomous underwater vehicles.     

Emulsion Stability as Affected by Competitive Adsorption Between an Oil-Soluble Emulsifier and Milk Proteins at the Interface

The effect of an oil-soluble emulsifier upon adsorption properties of β-casein and β-lactoglobulin at the oil-water interface was studied. Addition of emulsifier improved the emulsification properties, but lowered emulsion stability. Higher concentrations decreased emulsification capacity, due to an increase in oil phase viscosity, and interfered with several protein assays, except the o-phthaldialdehyde (OPA) assay. Depletion measurements revealed that the emulsifier displaced β-casein more readily than β-lactoglobulin from the surface of droplets, which correlated with emulsification and stability measurements. Displacement of proteins was not complete due to emulsifier-induced formation of a multiple w-o-w emulsion, which accounted for the missing protein in the continuous phase.     

RELATIONSHIPS OF SELECTED WHEAT PARAMETERS TO BURGHUL-MAKING QUALITY

Ten Triticum aestivum and eleven Triticum turgidum var. durum varieties were screened for their one thousand kernel weight (1000 KW), particle size index (PSI), sodium-dodecyl-sulfate (SDS) sedimentation volume, flour swelling power, protein content, amylose content and swelling power of starch. The varieties were processed to Burghul (parboiled wheat) and utilized in the preparation of Burghul Mufalfal and Kibbeh. The products were rated sensorially for particle separation and hardness (Burghul Mufalfal) and denseness (Kibbeh). Marked differences were noted between the aestivums and durums as to their 1000 KW, PSI and SDS-sedimentation volumes. Significant correlations were observed between the sensory ratings of the two Burghul-based products and the 1000 KW, PSI and SDS-sedimentation volumes. Cluster analysis, using the chemical/physicochemical parameters as variables, identified two clusters; a “durum” cluster (11 durums, 2 aestivums) and an “aestivum” cluster (8 aestivums). The varieties of the “durum” cluster yielded quality Burghul Mufalfal and Kibbeh; the varieties of the “aestivum” cluster yielded inferior Burghul Mufalfal and less compact Kibbeh. Quality Burghul is best-processed from large size and hard-grained varieties of low SDS-sedimentation volumes (mostly durums) having 1000 KW > 34.5 g, 31.9 < PSI < 45.6 and 13.8 mL < SDS-sedimentation volumes < 30.1 mL.     

ABA during reproductive development in non-irrigated grapevines (Vitis vinifera L. cv. Tempranillo)

In grapevines, stomatal aperture decreases after a mid-morning peak during summer days. Afternoon stomatal closure increases in non-irrigated plants as water limitation progresses, which suggests the involvement of abscisic acid (ABA) in the control of stomatal aperture. The objective of this work was to study the seasonal and diurnal time-courses of CO₂ assimilation rate, leaf conductance, leaf water potential +, and ABA concentration in xylem sap, leaves, flowers and berries in non-irrigated field-grown Tempranillo grapevines throughout reproductive development. Leaf decreased throughout fruit development because water availability decreased towards the end of the reproductive cycle. CO₂ assimilation rate, leaf conductance and xylem ABA concentration also decreased during the course of the growing season. Combining all measurements xylem ABA was either not correlated, or only slightly correlated, with leaf water status + and daily leaf conductance, respectively. This lack of relationship indicates that xylem ABA during fruit ripening had functions other than provision of a non-hydraulic signal. On a seasonal basis, xylem ABA concentration measured in non-irrigated grapevines was well related to berry ABA concentration, especially at the end of fruit development (veraison and harvest).     

Estimation of radiation hazard indices from natural radioactivity of some rocks

1 Introduction Naturally occurring radionuclides 226Ra, 232Th and 40K are widespread in the earth’s environment and they exist in various geological formation such as soil, rock, water and plants [1]. These radionuclides pose exposure risks externally due to their γ-ray emissions and internally due to radon and its progeny, which emit alpha particles. Even though these radionuclides are widely distributed, their concentrations have been found to depend on the local geological condition and …     

CHEMICAL COMPOSITION OF OIL FROM COULA EDULIS (Bail.) NUTS

Coula edulis (Bail.) nuts are generally used as food components in the littoral and southern part of Cameroon. The physicochemical characteristics, the fatty acids and the triacylglycerols (TGs) of Coula edulis (Bail.) nut oil from two different agroclimatical zones of Cameroon were studied. The oil content varied according to the zone (33.50 – 36.65%). The iodine value (90 – 95), saponification value (180 – 185) and the nitrogen (2.16 – 2.40%), and ash (2.5 to 2.7%) contents were similar for the two types of nuts studied. The main fatty acid of the oil was oleic acid (95.5 – 97.4%), as determined by capillary gas chromatographic analysis. The triacylglycerol profile obtained by reversed phase liquid