The analysis of solvation in ionic liquids and organic solvents using the Abraham linear free energy relationship

The contentions made in an earlier paper [J Chem Technol Biotechnol 80 : 133–137 (2005)] that the coefficients of the Abraham solvation equation do not provide meaningful information on the molecular properties of ionic liquid solvents is refuted. The objections noted in the earlier paper disappear when the solvation equation model is correctly applied to the experimental data. It is further shown that the coefficients of the Abraham solvation equations can be used to characterize ionic liquids and can be used to select solvents for the solubility of gaseous solutes. Copyright © 2006 Society of Chemical Industry     

A Single-Die 124 dB Stereo Audio Delta-Sigma ADC With 111 dB THD

This paper presents a highly power-efficient stereo delta-sigma ADC designed for high-precision applications, with measured inter-channel isolation over 130 dB. This design adopts a single-loop, fifth-order, 33 level analog modulator with positive and negative feedforward paths. An interpolated multilevel quantizer with unevenly weighted quantization levels replaces a conventional 5-bit flash type quantizer. These new techniques suppress signal dependent energy inside the delta-sigma loop, reduce internal channel coupling and power consumption. Manufactured in 0.35 mum double poly, three metal CMOS process, the single-die chip includes two analog modulators, on-chip bandgap reference circuit, decimation filter and serial interface circuits. The core die area is around 14.8 mm². The ADC achieves 124 dB dynamic range (A-weighted), -111 dB THD over 20 kHz bandwidth. Total power consumption is less than 330 mW.     

Heat transfer coefficients and other performance parameters for variously positioned and supported thermal loads in ovens with/without water-filled or empty blockages

An in-depth experimental study of heat transfer in ovens has provided basic data that is directly applicable to design. Heat transfer coefficients were measured for thermal loads having either black or highly reflective surface finishes. Approximately 100 different data runs were carried out. These heat transfer coefficients enabled the separation of the heat transfer into convective and radiative components, with radiation being the dominant transfer mechanism for blackened loads. The thermal response of the load to the presence of blockages situated either below or above the load was quantified. This response was only slightly affected by the blockages when they were empty of water, but major effects were observed when the blockages were water filled. Major effects were also encountered when the load was supported from below by cookie sheets. On the other hand, extensive investigation of various positions throughout the oven indicated a very weak effect of load position on the thermal response.     

Potato gun ocular injury

PURPOSE: This study aimed to identify a dangerous new weapon capable of causing damage to the ocular and periocular regions. METHODS: The authors report two patients who had penetrating ocular injury in the past year because of homemade recreational potato guns. RESULTS: In one 14-year-old boy, projectiles from the firing of a potato gun resulted in orbital and cranial injuries that were life threatening with widespread fractures, marked disruption of facial structures, a cerebrospinal fluid fistula requiring bifrontal surgical repair, and loss of one eye. In a separate accident with a different potato gun, a 14-year-old boy who was wearing glasses at the time of injury had a sight-threatening perforating corneal laceration. CONCLUSION: Practitioners must be aware of the existence of these new, homemade unregulated devices. Information about the use and construction of these guns is widespread on the Internet, but no injuries resulting from these guns currently are documented in the medical literature.     

Null values in nested relational databases

Summary The desire to extend the applicability of the relational model beyond traditional data-processing applications has stimulated interest in nested or non-first normal form relations in which the attributes of a relation can take on values which are sets or even relations themselves. In this paper, we study the role of null values in the nested relational model using an open world assumption. We extend the traditional theory and study the properties of extended operators for nested relations containing nulls. The no-information, unknown, and non-existent interpretation of nulls are discussed and the meaning of empty set is clarified. Finally, contrary to several previous results, we determine that the traditional axiomatization of functional and multivalued dependencies is valid in the presence of nulls.Currently with the Air Force Institute of Technology, AFIT/ENG, Wright-Patterson AFB, OH 45433, USAResearch partially supported by an IBM Faculty Development A ward and NSF grant DCR-8507224     

Copper coating on carbon fibres and their composites with aluminium matrix

A uniform and continuous coating of copper was given to carbon fibres by cementation or electroless techniques. In both cases, when coating thicknesses were less than 0.2 m, copper deposition was discontinuous over the fibres, and above 0.2 m, coatings were continuous. In electroless coating, about 75% of the continuously coated fibres had a coating thickness range 0.2–0.5 m and above this showed isolated dendrite deposits of copper. In the cementation process, about 75% of the continuously coated fibres had a coating thickness range 0.2–0.6 m, and above this thickness, fine crystallite-type copper deposition was found over smoothly coated copper. The ultimate tensile strength of continuously electroless-coated fibres were nearer to the uncoated fibres, suggesting defect-free coating, while fibres coated by the cementation process exhibited lower ultimate tensile strength values. The tensile fracture of both electroless- and cementation-coated fibres showed delamination of the coating, suggesting poor bonding between coating and the fibre. In composites, prepared by dispersing the coated chopped fibres in a pure aluminium matrix, uniform and random distribution of the fibres were observed without appreciable fibre-metal interaction. The CuAl₂ intermetallics were largely found in the matrix and only very small amounts were observed at fibre/matrix interfaces. Additions of about 2 wt% Mg to the matrix prior to the fibre dispersion did not appreciably change the distribution pattern of the fibres, but in addition to CuAl₂ phase, Mg₂Si phases were observed in the matrix as well as at the interface.     

Effet of Nikel Alloying on the Thermal Diffusivity/ondutivity of MgO Single rystals

The thermal diffusivity/conductivity of Ni-doped MgO single crystals was measured as a function of temperature by the laser-flash method. Nickel in the form of the substitutional solid solution, Ni²⁺, has a much greater effect on the thermal diffusivity / conductivity than precipitated Ni colloids. These results are discussed in terms of phonon and photon scattering effects.     

Models of Influence in Online Social Networks

Online social networks gained their popularity from relationships users can build with each other. These social ties play an important role in asserting users' behaviors in a social network. For example, a user might purchase a product that his friend recently bought. Such phenomenon is called social influence, which is used to study users' behavior when the action of one user can affect the behavior of his neighbors in a social network. Social influence is increasingly investigated nowadays as it can help spreading messages widely, particularly in the context of marketing, to rapidly promote products and services based on social friends' behavior in the network. This wide interest in social influence raises the need to develop models to evaluate the rate of social influence. In this paper, we discuss metrics used to measure influence probabilities. Then, we reveal means to maximize social influence by identifying and using the most influential users in a social network. Along with these contributions, we also survey existing social influence models, and classify them into an original categorization framework. Then, based on our proposed metrics, we show the results of an experimental evaluation to compare the influence power of some of the surveyed salient models used to maximize social influence.