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In this study gasification in air of activated carbons and carbon blacks is investigated using a simultaneous TG-DTA unit. It is found that a final acid or alkaline treatment can substantially alter their reactivity in the gasification reaction in air. To make a proper assessment of their solid state reactivity with respect to their gasification in air a simple method is advanced which has been used recently in assessing solid state reactivity of other materials. In this method a thermogravimetric (TG) plot is obtained on a reference carbon and then similar TG plots are obtained on the other samples of carbon using identical experimental conditions and the same TG unit. The solid state reactivity is assessed from plots of the αR (the value of αR, the extent of the gasification of the reference carbon) against the sample carbons values of the αS (labeled αS to denote the value of the various carbon samples). The values of appropriate couples of αR and αS at temperaturesT 1,T 2,T 3,...Tn allow an αRS plot to be constructed. If the solid state reactivity of the carbon samples matches exactly that of the reference carbon the result will be a linear plot, showing coincidence of αS and αR at all values of αR. If the solid state reactivity of a carbon sample exceeds that of the reference carbon then the lines plotted will be on one side of the coincidence plot, while if they are less than the carbon reference they will lie on the other side. The results show that treatment of a carbon with alkaline or acid may have a significant effect on the reactivity of the carbon sample which is only partly explained by observable differences in surface area.

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The rate of removal and uptake of guests into layered and porous materials is important in many areas of materials chemistry. Here we report on the use of atmospheric thermogravimetry linked to a mass spectrometer (TG-MS) to investigate the thermal characteristics of three different solids. We show that (i) the desorption of cyclohexylamine from the surface of a pillared acid activated smectite clay occurs in two stages, indicating two possible acidic binding sites, (ii) TG-MS is an extremely sensitive technique for probing progressive anion exchange of lithium aluminium layered double hydroxides, (iii) on heating, the perhydrate 4Na2SO4·NH4Cl·2H2O2 releases H2O2 intact.

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A low cost neutron capture prompt gamma activation analysis facility has been constructed at The University of Michigan's Pheonix Memorial Laboratory. Although the neutron beam used has a fairly large epithermal component (Cd ratio 7.1), background levels are low enough to result in satisfactory measurement of over 16 different elements. For the elements of greatest sensitivity (samarium, boron, gadolinium, and cadmium) minimum detectable levels of 3.6·10−5 to 1.4·10−5 gram for a one hour measurement are possible. The fast neutrons incident to the detector were found to be minimal. Estimates of up to 3 years of continuous operation before measurable damage is expected.

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Silicon has been found to be an essential element for the growth and development of many ecomomically important plants such as sugarcane, rice, oats, and wheat. A method is described for the quantitative determination of silicon in plant samples. Measurements were made with two Ge(Li) detectors matched with a multiplexing unit to provide a single amplified signal to a computerized analyzer system. For those materials containing greater than 0.5 weight percent silicon, the reaction29Si(n, p)29Al (1273 keV) provides a direct measurement of the quantity of silicon provided the irradiation is done in a special boron nitride capsule to reduce interferences from thermal neutron reactions and a correction is made for the single escape line from28Al (1268 keV). For lesser quantities of silicon, a technique which utilizes the fast neutron reaction28Si(n, p)28Al is preferred. Corrections for the interference produced by the presence of phosphorus31P(n, α)28Al are made by determining the phosphorus content following the instrumental analysis using a unique application of neutron activation analysis, i. e., measurement of tungsten in tungstomolybdophosphoric acid produced when molybdate and tungstate ions are added to dissolved samples of the plant material containing phosphorus. Aluminum, which may also produce an interference by thermal neutron reaction27Al(n, γ)28Al, is determined directly from the original activation data after subtracting out the effect of the phosphorus. Thus, three irradiations in the pneumatic sample irradiator are necessary; one short irradiation (1 min) without thermal neutron shielding, a longer irradiation (6 min) in the boron capsule, and a final irradiation of the tungstomolybdophosphoric acid provide all data required to accurately determine silicon in plant materials. A computer program has been developed that provides rapid reduction of the data in final report format. Elements such as sodium, chlorine, calcium, manganese, potassium, and magnesium extrinsic to the analysis for silicon are also determined by this method. The method has been tested on a large number of samples and reliable results are obtained with less than 0.2 g of sample.

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Abstract  

Derivative activation analysis is a technique in which the element or chemical entity to be determined is either replaced or complexed in a preirradiation chemical procedure with another element for which neutron activation analysis has an intrinsically higher sensitivity. Although the technique has many potential applications, the literature of the field is very limited. Examples of recent applications in our laboratory include: determination of P in natural waters, biological reference standards, brain tissue, rocks and coal; determination of Ni in a stony meteorite; determination of T1 in solutions; and speciation of oxygen (e.g., hydroxyl and carbonyl moieties) in coal via 14 MeV neutron activation.

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The reduction of NiO by H2 was followed by conventional thermogravimetry and a new evolved gas analysis approach which follows the course of the reaction by measuring the H2O content of the gas stream. Excellent correspondence is observed between the two techniques for simultaneous measurements. Heating rates between 0.5 and 10° min−1 shift the temperature of the reaction as does changing the surface area of the NiO. These shifts are discussed in terms of the Neel temperature (T N) of NiO and the thermal history of the sample. No correlation between reaction rate andT N is observed under dynamic conditions. Preheating the sample in vacuum at 130° has a marked effect on shape of the DTG and EGA curves.

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A method for the quantitative determination of small amounts of protein samples was developed employing neutron activation analysis. Current methods of protein concentration determination are severely limited as a result of differences in the specific characteristics of each protein. Silver binding has been used as a sensitive colorimetric method to indicate the presence of protein. However, silver-protein complexes can have a variety of absorbance spectra unique to each protein, which complicate the analysis. Various amounts of specific proteins were equilibrated in an excess of silver nitrate prior to the reduction of the silver by the addition of NaBH4, HCHO, and NaOH. The protein-silver complex was rapidly separated from the unbound silver by centrifugation chromatography and the amount of bound silver was determined by INAA. The amount of silver was proportional to the amount of protein present in each sample. When the silver was not reduced prior to removal of the unbound silver by chromatography, only negligible amounts of silver remained bound to the protein. The stoichiometry of bound silver to protein on a molar basis showed relatively small differences for the proteins that were examined. This ratio was found to depend on the conditions of the binding and reduction of the silver. The results suggest that the binding of silver is not specific to any charged or polar groups on these proteins and may, therefore, provide a means of determination of the concentration of protein that has general application for all proteins.

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In the present report, thermal analysis (TMDSC, DMA, TG, stress-strain analysis), nano-indentation and AFM morphological characterization of cross-linkable latexes, prepared with either a pre-coalescence cross-linker (1,3-butylene glycol dimethacrylate) or post-coalescence cross-linker (adipic dihydrazide) at various levels of cross-linking, were done. The study assesses the effect of type and level of cross-linking on the film formation process through the evolution of mechanical properties and latex morphology. In addition, the final fundamental thermal and mechanical properties, specific end-use properties and latex morphology resulting from the film formation process are reported.

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FoxP2 is a member of the winged helix/forkhead class of transcription factors. Despite FoxP2 is found to have particular relevance to speech and language, the role of this gene is broader and not yet fully elucidated. In this study, we investigated the expression of FoxP2 in the brains of bats with different feeding habits (two frugivorous species and three insectivorous species). We found FoxP2 expression in the olfactory tubercle of frugivorous species is significantly higher than that in insectivorous species. Difference of FoxP2 expression was not observed within each of the frugivorous or insectivorous group. The diverse expression patterns in olfactory tubercle between two kinds of bats indicate FoxP2 has a close relation with olfactory tubercle associated functions, suggesting its important role in sensory integration within the olfactory tubercle and such a discrepancy of FoxP2 expression in olfactory tubercle may take responsibility for the different feeding behaviors of frugivorous and insectivorous bats.

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