Synthesis,characterisation and thermal behaviour of lithium aluminosilicate inorganic polymers

Lithium aluminosilicate inorganic polymers were synthesised from dehydroxylated kaolin-type clay (halloysite) by the conventional method under highly alkaline conditions with lithium hydroxide or lithium silicate solutions of two different Li₂O/SiO₂ molar ratios. Variants were also developed of a solid-state synthesis method involving the thermal reaction of dehydroxylated halloysite with LiOH followed by hydration of the product. The molar compositions of the materials prepared by all three methods (SiO₂/Al₂O₃ = 2.41–3.27, Li₂O/SiO₂ = 0.30–0.61, and H₂O/Li₂O = 9.33–10.40) fall within the range of compositions previously reported to produce viable geopolymers. Curing at 40 °C produces solid samples of varying viability depending on the amount of synthesis water. The cured materials are not characteristically X-ray amorphous, but contain the lithium zeolites Li-ABW and fibrous Li-EDI, the latter in the materials synthesised by solid-state reaction. The ²⁷Al and ²⁹Si MAS NMR spectra of the cured materials contain narrow resonances more characteristic of zeolites than of inorganic polymers. Heating the synthesised products at <800 °C produces β-eucryptite, LiAlSiO₄. In a further series of thermal reactions, β-spodumene, LiAlSi₂O₆ is formed at 900 °C, decomposing at 1100 °C to form additional β-eucryptite. At 1275 °C, β-spodumene reappears in the samples of higher silica content. Judicious manipulation of the composition and thermal treatment of the Li-zeolites formed in these lithium aluminosilicate syntheses could make them useful precursors to β-eucryptite and β-spodumene ceramics.     

Prediction of Air-Drying of Milk Droplet Under Relatively High Humidity Using the Reaction Engineering Approach

Spray-drying is the prime process for manufacturing powders. Optimization of spray-drying processes requires both modeling the drying characteristics of a single milk droplet and the dryer-wide simulations incorporating computational fluid dynamics. In computational fluid dynamics simulations, it is desirable to have an accurate yet simple model for drying of single droplet, which does not require resolving partial differential equation. Here the experimental results on constant drying conditions with high humidity air flows are reported for the first time. Previously, a mathematical model using the reaction engineering approach (the REA model) was established using the very dry air conditions. The same REA model has been used to predict the current high humidity results. It has been shown that the predictions agree well with the experimental results, showing the good promise of this approach.     

Structural characterization of a “Signature” phosphatidylethanolamine as the major 10-hydroxy stearic acid-containing lipid of Cryptosporidium parvum oocysts

A 10-hydroxy stearic acid-containing lipid from Cryptosporidium parvum was purified by thin-layer chromatography and analyzed by infrared spectroscopy, fast-atom bombardment mass spectrometry, ¹H and ³¹P nuclear magnetic resonance spectroscopy, and was identified as phosphatidylethanolamine.     

Microstructure and phase identification in type 304 stainless steel-zirconium alloys

Stainless steel-zirconium alloys have been developed at Argonne National Laboratory to contain radioactive metal isotopes isolated from spent nuclear fuel. This article discusses the various phases that are formed in as-cast alloys of type 304 stainless steel and zirconium that contain up to 92 wt pct Zr. Microstructural characterization was performed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and crystal structure information was obtained by X-ray diffraction. Type 304SS-Zr alloys with 5 and 10 wt pct Zr have a three-phase microstructure—austenite, ferrite, and the Laves intermetallic, Zr(Fe,Cr,Ni)_2+x. whereas alloys with 15, 20, and 30 wt pct Zr contain only two phases—ferrite and Zr(Fe,Cr,Ni)_2+x. Alloys with 45 to 67 wt pct Zr contain a mixture of Zr(Fe,Cr,Ni)_2+x and Zr₂(Ni,Fe), whereas alloys with 83 and 92 wt pct Zr contain three phases—α-Zr, Zr₂(Ni,Fe), and Zr(Fe,Cr,Ni)_2+x. Fe₃Zr-type and Zr₃Fe-type phases were not observed in the type 304SS-Zr alloys. The changes in alloy microstructure with zirconium content have been correlated to the Fe-Zr binary phase diagram.     

Surface Wave Forces Acting on Submerged Logs

Drag forces exerted on cylindrical simulated logs by flowing water are measured in a laboratory flume. Drag coefficient values calculated from these data are presented for a range of log submergence and slenderness values. Drag coefficients for large submergence values are consistent with those previously published. However, at submergence values less than eight element diameters, the observed drag coefficients are consistently higher than those previously published. This discrepancy is due to the additional drag created by stationary surface waves which causes the drag coefficient to increase considerably when a log is positioned near the free surface. This phenomenon, which has not been accounted for in previous studies on large woody debris, is shown to depend on log slenderness, submergence, and Froude number.     

Evidence for Self-Organized Sentence Processing: Digging-In Effects.

Dynamical, self-organizing models of sentence processing predict "digging-in" effects: The more committed the parser becomes to a wrong syntactic choice, the harder it is to reanalyze. Experiment 1 replicates previous grammaticality judgment studies (F. Ferreira & J. M. Henderson, 1991b, 1993), revealing a deleterious effect of lengthening the ambiguous region of a garden-path sentence. The authors interpret this result as a digging-in effect. Experiment 2 finds a corresponding effect on reading times. Experiment 3 finds that making 2 wrong attachments is worse than making 1. Non-self-organizing models require multiple stipulations to predict both kinds of effects. The authors show that, under an appropriately formulated self-organizing account, both results stem from self-reinforcement of node and link activations, a feature that is needed independently. An implemented model is given. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

PhysicsGP: A Genetic Programming approach to event selection

We present a novel multivariate classification technique based on Genetic Programming. The technique is distinct from Genetic Algorithms and offers several advantages compared to Neural Networks and Support Vector Machines. The technique optimizes a set of human-readable classifiers with respect to some user-defined performance measure. We calculate the Vapnik-Chervonenkis dimension of this class of learning machines and consider a practical example: the search for the Standard Model Higgs Boson at the LHC. The resulting classifier is very fast to evaluate, human-readable, and easily portable. The software may be downloaded at: http://cern.ch/~cranmer/PhysicsGP.html.     

Bacillus subtilis RNase III gene: cloning, function of the gene in Escherichia coli, and construction of Bacillus subtilis strains with altered rnc loci

The rnc gene of Bacillus subtilis, which has 36% amino acid identity with the gene that encodes Escherichia coli RNase III endonuclease, was cloned in E. coli and shown by functional assays to encode B. subtilis RNase III (Bs-RNase III). The cloned B. subtilis rnc gene could complement an E. coli rnc strain that is deficient in rRNA processing, suggesting that Bs-RNase III is involved in rRNA processing in B. subtilis. Attempts to construct a B. subtilis rnc null mutant were unsuccessful, but a strain was constructed in which only a carboxy-terminal truncated version of Bs-RNase III was expressed. The truncated Bs-RNase III showed virtually no activity in vitro but was active in vivo. Analysis of expression of a copy of the rnc gene integrated at the amy locus and transcribed from a p(spac) promoter suggested that expression of the B. subtilis rnc is under regulatory control.     

An integrated testbed for wireless multimedia computing

A testbed has been constructed to evaluate node architectures that support multimedia applications and services across a wireless network. Using this testbed, a low bitrate subband video compression algorithm has been prototyped in a field programmable gate array (FPGA) and evaluated for video networking across bandwidth-limited RF channels. A radio interface has been prototyped in an FPGA and a common applications programming interface (API) has been developed to allow experimentation with multiple radios. This testbed has been used to evaluate node performance under two different wireless applications: 1) simultaneous video and data networking (VTALK) and 2) TCP/IP utilities such as FTP and telnet. Based on this evaluation, the design of a battery-operated high throughput wireless multimedia node is presented.