Hard Data Is Good to Find

Indices are a common and useful way to summarize a changing field for both the lay and the specialist reader, and it's time that we had them for information security.     

Metal microparticle – Polymer composites as printable,bio/ecoresorbable conductive inks

Biologically and environmentally resorbable electronic devices support application possibilities that cannot be addressed with conventional technologies. This paper presents highly conductive, water-soluble composites that can be printed to form contacts, interconnects, antennas, and other important features that are essential to nearly all systems of this type. An optimized material formulation involves in situ polymerization to yield a polyanhydride containing a dispersion of molybdenum microparticles at appropriate concentrations. Comparisons of essential physical and electrical properties of these materials to those of composites formed with other polymers and other metal microparticles reveal the relevant considerations. Various functional demonstrations of screen-printed test structures and devices illustrate the suitability of these conductive inks for use in water-soluble electronic devices. A key advantage of the material introduced here compared to alternatives is its ability to maintain conductance over significant periods of time while immersed in relevant aqueous solutions. Studies involving live animal models establish the biocompatibility.     

The effect of curing on the crystallization of poly(phenylene sulfide)

Summary Poly(phenylene sulfide) (PPS) was cured in the melt and solid states under air and/or nitrogen environments. Crystallization behavior of such cured materials as a function of cure time at 320°C and 255°C was studied via differential scanning calorimetry. It was found, on general, that while short-time curing leads to an increase in crystallization rate, prolonged curing leads to a decrease in both crystallinity and crystallization rate. In contrast to the enhanced crystallization rate caused by curing in nitrogen at the melt state, no significant change of crystallization rate is observed while curing is done in the solid state (in nitrogen).     

Articulating collaboration in a learning community

A common computer-based collaborative learning approach is to simply introduce contemporary computermediated communication technology into the classroom to support prescribed learning activities. This approach assumes that all students collaborate in similar ways and that presentday technology is sufficient to accommodate all collaboration forms. This view is superficial and limiting. Students collaborate in different ways at different levels on different learning activities. A more detailed articulation of collaboration in learning is crucial to understanding and extending the pedagogical capabilities and usefulness of collaborative technologies. A model is presented for a more finely articulated form of analysis that enumerates types of collaborative learning activities and evaluates how these activities may be supported through different design options. The analysis is based on actual classroom scenarios and the collaboration requirements that emerge from them. The authors have successfully applied this analysis model in the design of a computer-based collaborative learning environment for science education.     

Acceleration and filtering in the generalized Landweber iteration using a variable shaping matrix

The generalized Landweber iteration with a variable shaping matrix is used to solve the large linear system of equations arising in the image reconstruction problem of emission tomography. The method is based on the property that once a spatial frequency image component is almost recovered within in in the generalized Landweber iteration, this component will still stay within in during subsequent iterations with a different shaping matrix, as long as this shaping matrix satisfies the convergence criterion for the component. Two different shaping matrices are used: the first recovers low-frequency image components; and the second may be used either to accelerate the reconstruction of high-frequency image components, or to attenuate these components to filter the image. The variable shaping matrix gives results similar to truncated inverse filtering, but requires much less computation and memory, since it does not rely on the singular value decomposition.     

Mixed sulfated tallow alkanolamides as lime soap dispersing agents

Sulfated alkanolamides of hydrogenated tallow fatty acids have been shown to possess excellent lime soap dispersing and detergent properties. However the high melting points of the alkanolamides and their relative insolubility in organic solvents such as dichloroethane make sulfation on an industrial scale awk ward. This difficulty has been overcome by the use of a eutectic mixture of the N-(2-hydroxypropyl)amide and N-(2-[2-hydroxyethoxy]ethyl)amide of unhydrogenated tallow fatty acids. The sulfation of such a mixture can be carried out at or slightly above room temperature, and only a small amount of a chlorinated solvent is required in order to keep the sulfation mixture fluid. The resulting sulfated mixed alkanolamide is an excellent lime soap dispersing agent, which is formulated readily with tallow soap and a glassy silicate into an effective heavy duty detergent.     

Assay of aflatoxin in peanuts and peanut products using acetone-hexane-water for extraction

A quantitative method is described for the assay of aflatoxin in peanut products. The procedure involves extraction of aflatoxin from the sample with a homogeneous acetone-hexane-water solvent mixture followed by purification of the extract by phasic extraction of the aflatoxin with aqueous sodium chloride and then with chloroform. The purified chloroform extract is analyzed by thin-layer chromatography by comparison of the intensity of fluorescence of any aflatoxin with the intensity of a known standard. The aflatoxin analyses of peanuts were found to be very variable due to sampling, and this variability has been greatly reduced by finely grinding and thoroughly mixing 2 kg of the sample before removal of an aliquot for assay. The method is sensitive to approximately 2 parts per billion. Honorable mention, Bond Award competition. Presented at AOCS Meeting, Chicago, Illinois, October, 1964. So. Reg. Res. Lab., New Orleans, Louisiana, one of the laboratories of the So. Utiliz. Res. and Dev. Div., ARS, USDA.     

Approximating total citation counts from first author counts and from total papers

This paper is an attempt to improve on the approximation. First author citations (C_f)≈Total citations (C_t) of an author's publications without the work of making the complete citation count under the author and all co-author names. Using the bibliographies of all faculty from each of four large departments: Physics, Chemistry, Materials Sciences, and Biosciences, in the same university, both first author and complete citation counts were made, care being taken to avoid the most common errors in such counts. It is shown that the function C_f·T/F (where T and F are the total number of papers and F those with subject author's name first) correlates strongly (>90%) with C_t. We find also that C_t correlates strongly with T. The data also may be used as one more line of evidence to obtain normalizing ratios for possible comparisons of productivityacross different disciplinary universes. A very tentative ratio from different studies would be 8 (Chem.)=4 (Physics)=2.5 (Mat. Sci.)=2 (Mathematics)=4.5 (Biophysics-Biochemistry).