Perfluoroether triazine elastomers

The synthesis of high performance elastomers with the high thermal stability and chemical, inertness of perfluoroalkylene triazine and a low glass transition temperature is discussed. Perfluorether triazine elastomers were proposed as potentially superior. It is concluded that the difficulties experienced in fluoroalkytriazine elastomer synthesis can be overcome by a four-step reaction process involving chain extension, triazine ring closure, crosslinking, and elastomer curing. Molecular weight can be controlled in the initial polymer formation so that elastomer modulus can be determined. The final product elastomers exhibit a useful elastomeric range of approximately 45 to 325 C with an oxidative stability superior to other broad range elastomers

Process for the preparation of fluorine containing crosslinked elastomeric polytriazine and product so produced

Crosslinking elastomeric polytriazines are prepared by a 4 step procedure which consists of (1) forming a poly(imidoylamidine) by the reaction, under reflux conditions, of anhydrous ammonia with certain perfluorinated alkyl or alkylether dinitriles; (2) forming a linear polytriazine by cyclizing the imidoylamidine linkages by reaction with certain perfluorinated alkyl or alkylether acid anhydrides or halides; (3) extending the linear polytriazine chain by further refluxing in anhydrous ammonia; and (4) heating to cyclize the new imidoylamidine and thereby crosslink the polymer

Catalytic conversion of toluene over a biochar bed under an inert atmosphere – The comparison of chars from different types of wood and the role of selected metals

In this paper, toluene, a tar-representing compound, was used in pyrolytic conversion tests with a wood-derived char catalyst. The decomposition mainly occurred via two competing heterogeneous reactions; the favoured reaction led to coke formation on the catalyst bed. With char saturation of the carbon deposit, a second demethylation reaction gained significance, until selectivity towards benzene formation reached 12–16%. By-products of the secondary reaction (xylenes, ethylbenzene and styrene) were also detected; however, no gas-phase toluene decomposition occurred. The principles of toluene conversion were the same for all of the examined chars from the different tree species. However, a quantitative difference was observed between the chars from the wood from coniferous and deciduous trees. Pine yielded char with less mesopores and active sites and thus demonstrated a lower efficiency as a catalyst for toluene decomposition. An assessment of alkali and alkaline earth metals importance revealed that, while their presence in the char strongly enhances its oxidation rate, they did not affect the toluene pyrolysis

Physicochemical properties of biochars prepared from raw and acetone-extracted pine wood

Biochars can be used in a wide range of applications, serving as soil additives, sorbents, fuels, catalyst supports or as catalysts themselves. There is however, a vast range of variables influencing the properties of biochars and their performance as catalysts. One of the characteristic features of pine wood is its high extractives content which is known to influence the pyrolysis process, therefore it can also affect the properties of the derived biochar. In this paper, raw and acetone-extracted pine wood was used to prepare steam-activated biochars. The changes in physicochemical properties of the chars upon the feedstock treatment were examined, including the analysis of surface area, porosity, acidic sites distribution, metals content and surface characterisation by FTIR and SEM techniques. A toluene pyrolytic conversion experiment was carried out to determine the chars' potential towards tar removal. At the initial stage of the process, toluene removal was higher for extracted than non-extracted pine char, and with time-on-stream their performance became similar. It was concluded that the removal of the extractives affected wood pyrolysis, creating char with significantly higher microporosity and increased acidity. Upon steam activation, the microporosity and acidity of both chars were enhanced in general while the difference between the samples diminished, while still improving toluene conversion in the early stages of the process

Perfluroether triazine elastomers

In order to obtain high performance elastomers with the high thermal stability and chemical inertness of perfluoroalkylene triazine and a low glass transition temperature, perfluoroether triazine elastomers were synthesized. The procedure for elastomer synthesis is described as well as general experimental methods. Results are presented and discussed. The screening of catalysts for the dehydration of perfluoroether diamide is also considered

Dictionary Attacks on Speaker Verification

In this paper, we propose dictionary attacks against speaker verification - a novel attack vector that aims to match a large fraction of speaker population by chance. We introduce a generic formulation of the attack that can be used with various speech representations and threat models. The attacker uses adversarial optimization to maximize raw similarity of speaker embeddings between a seed speech sample and a proxy population. The resulting master voice successfully matches a non-trivial fraction of people in an unknown population. Adversarial waveforms obtained with our approach can match on average 69% of females and 38% of males enrolled in the target system at a strict decision threshold calibrated to yield false alarm rate of 1%. By using the attack with a black-box voice cloning system, we obtain master voices that are effective in the most challenging conditions and transferable between speaker encoders. We also show that, combined with multiple attempts, this attack opens even more to serious issues on the security of these systems

What’s New in Plant Pathology

Extension Plant Pathology Team Update Plant and Pest Diagnostic Clinic Update Disease Management Products Table 1. Foliar Fungicide Label Updates Table 2. New Product

p_T-fluctuations in high-energy p-p and A-A collisions

The event-by-event p_T-fluctuations in proton-proton and central Pb-Pb collisions, which have been experimentally studied by means of the so-called Phi-measure, are analyzed. The contribution due to the correlation which couples the average p_T to the event multiplicity is computed. The correlation appears to be far too weak to explain the preliminary experimental value of Phi (p_T) in p-p interactions. The significance of the result is discussed.Comment: 5 pages, 2 figures, minor improvement

Landscape and Garden Plants Sample Submission to the Plant and Pest Diagnostic Clinic

Diagnoses are made easier and turnaround time is improved when the quality of plant samples is maintained. This NebGuide discusses the proper guidelines for submitting landscape and garden plants, turf, and tree samples to UNL’s Plant and Pest Diagnostic Clinic. There are several important things to consider when collecting, packaging, and sending plant or insect samples for diagnosis in a plant diagnostic laboratory. Collect an adequate amount of plant material. When feasible, the sample should include the entire plant — roots, stems, leaves, flowers, and fruits. Whole plants are needed to properly evaluate the sample. If the whole plant is not available, photos of the symptomatic plants can improve accuracy of diagnosis