Rich methane laminar flames doped with light unsaturated hydrocarbons. Part II: 1,3butadiene

In line with the study presented in the part I of this paper, the structure of a laminar rich premixed methane flame doped with 1,3-butadiene has been investigated. The flame contains 20.7% (molar) of methane, 31.4% of oxygen and 3.3% of 1,3-butadiene, corresponding to an equivalence ratio of 1.8, and a ratio C4H6 / CH4 of 16 %. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 36 cm/s at 333 K. The temperature ranged from 600 K close to the burner up to 2150 K. Quantified species included usual methane C0-C2 combustion products and 1,3-butadiene, but also propyne, allene, propene, propane, 1,2-butadiene, butynes, vinylacetylene, diacetylene, 1,3-pentadiene, 2-methyl-1,3-butadiene (isoprene), 1-pentene, 3-methyl-1-butene, benzene and toluene. In order to model these new results, some improvements have been made to a mechanism previously developed in our laboratory for the reactions of C3-C4 unsaturated hydrocarbons. The main reaction pathways of consumption of 1,3-butadiene and of formation of C6 aromatic species have been derived from flow rate analyses. In this case, the C4 route to benzene formation plays an important role in comparison to the C3 pathway

Susceptibility of Mycobacterium immunogenum and Pseudomonas fluorescens to Formaldehyde and Non-Formaldehyde Biocides in Semi-Synthetic Metalworking Fluids

Mycobacterium immunogenum, a newly identified member of the Mycobacterium chelonae_M. abscessus complex is considered a potential etiological agent for hypersensitivity pneumonitis (HP) in machine workers exposed to contaminated metalworking fluid (MWF). This study investigated the biocidal efficacy of the frequently applied commercial formaldehyde-releasing (HCHO) biocides Grotan and Bioban CS 1135 and non-HCHO type biocides Kathon 886 MW (isothiazolone) and Preventol CMK 40 (phenolic) toward this emerging mycobacterial species (M. immunogenum) in HP-linked MWFs, alone and in presence of a representative of the Gram-negative bacterial contaminants, Pseudomonas fluorescens, using two semi-synthetic MWF matrices (designated Fluid A and Fluid B). Relative biocide susceptibility analysis indicated M immunogenum to be comparatively more resistant (2–1600 fold) than P. fluorescens to the tested biocides under the varied test conditions. In terms of minimum inhibitory concentration, Kathon was the most effective biocide against M. immunogenum. Fluid factors had a major effect on the biocide susceptibility. Fluid A formulation provided greater protective advantage to the test organisms than Fluid B. Fluid dialysis (Fluid A) led to an increased biocidal efficacy of Grotan, Kathon and Preventol against M. immunogenum further implying the role of native fluid components. Used fluid matrix, in general, increased the resistance of the two test organisms against the biocides, with certain exceptions. M. immunogenum resistance increased in presence of the co-contaminant P. fluorescens. Collectively, the results show a multifactorial nature of the biocide susceptibility of MWF-colonizing mycobacteria and highlight the importance of more rigorous efficacy testing and validation of biocides prior to and during their application in metalworking fluid operations

Karl Murhard, Gelehrter und liberaler Nationaloekonom in Kassel: ein Beitrag zur Wirkungsgeschichte der klassischen Nationaloekonomie im Uebergang zur Industriegesellschaft in Kurhessen

Kassel, Gesamthochsch., Univ., Diss.Available from Bibliothek des Instituts fuer Weltwirtschaft, ZBW, Duesternbrook Weg 120, D-24105 Kiel A 185673 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Pour le droit d'asile, rassemblement !Avec les extraits des discours prononcés lors de la Conférence internationale pour le droit d'asile tenue à Paris les 20 et 21 juin 1936... / Harry Olten

Avec mode text

Self-Propagating Frontal Polymerization in Water at Ambient Pressure

Advances in polymer chemistry have led to the development of monomers and initiation agents that enable propagating free-radical polymerization fronts to exist. These fronts are driven by the exothermicity of the polymerization reaction and the transport of heat from the polymerized product to the reactant monomer/solvent/initiator solution. The thermal energy transported to the reactant solution causes the initiator to decompose, yielding free radicals, which start the free radical polymerization process as discussed in recent reviews. The use of polymerization processes based on propagating fronts has numerous applications. Perhaps the most important of these is that it enables rapid curing of polymers without external heating since the polymerization process itself provides the high temperatures necessary to initiate and sustain polymerization. This process also enables more uniform curing of arbitrarily thick samples since it does not rely on heat transfer from an external source, which will necessarily cause the temperature history of the sample to vary with distance from the surface according to a diffusion-like process. Frontal polymerization also enables filling and sealing of structures having cavities of arbitrary shape without having to externally heat the structure. Water at atmospheric pressure is most convenient solvent to employ and the most important for practical applications (because of the cost and environmental issues associated with DMSO and other solvents). Nevertheless, to our knowledge, steady, self-propagating polymerization fronts have not been reported in water at atmospheric pressure. Currently, polymerization fronts require a high boiling point solvent (either water at high pressures or an alternative solvent such as dimethyl sulfoxide (DMSO) (boiling point 189 C at atmospheric pressure.) Early work on frontal polymerization, employed pressures up to 5000 atm in order to avoid boiling of the monomer/solvent/initiator solution. High boiling point solutions are needed because in order to produce a propagating front, a high front temperature is needed to produce sufficiently rapid decomposition of the free radical initiator and subsequent free radical polymerization and heat release at a rate faster than heat losses remove thermal energy from the system. (While the conduction heat loss rate increases linearly with temperature, the free radical initiator decomposition is a high activation energy process whose rate increases much more rapidly than linearly with temperature, thus as the temperature decreases, the ratio of heat loss to heat generation increases, eventually leading to extinction of the front if the temperature is too low.) In order to obtain atmospheric pressure frontal polymerization in water, it is necessary to identify a monomer/initiator combination that is water soluble and will not extinguish even when the peak temperature (T*) is less than 100 C. In this work acrylic acid (AA) was chosen as the monomer because is it one of the most reactive monomers and can polymerize readily at low temperatures even without initiators. Ammonium persulfate (AP) was chosen as the initiator because it decomposes readily at low temperatures, produces relatively few bubbles and is commercially available. The propagation rates and extinction conditions of the fronts are studied for a range of AA and AP concentrations. Small amounts of fumed silica powder (Cab-o-sil, Cabot Corporation) were added to the solutions to inhibit buoyancy induced convection in the solutions; future studies will investigate the effects of buoyant convection within the solutions

Meta-Analysis of Placebo Response in Adult Antidepressant Trials

Background Roughly 80% of the symptom improvement experienced on antidepressants in clinical trials is also observed in the placebo comparison group. Understanding the correlates of placebo improvement and response is important to designing efficient and successful trials of future antidepressants. Objective The objective of this meta-analysis was to investigate the magnitude of placebo symptom improvement and placebo response rates in second-generation antidepressant trials of depression, anxiety, and obsessive-compulsive disorder. Methods We searched PubMed on 10 June, 2016, with no date or language limits, to identify randomized placebo-controlled trials of second-generation antidepressants in adults with depression, anxiety, or obsessive-compulsive disorder. We used a random-effects meta-analysis to examine the magnitude of placebo symptom improvement using standardized mean difference and placebo response rate. Stratified subgroup analysis and meta-regression were utilized to examine the effect of diagnostic indication and correlates of placebo symptom improvement. Results The meta-analysis included 164 trials involving 19,591 participants. Magnitude of placebo improvement and placebo response rates varied significantly between diagnostic indications. The magnitude of placebo improvement was much lower in obsessive-compulsive disorder (standardized mean difference = 0.58, 95% confidence interval 0.36-0.79) than in depression (standardized mean difference = 1.22, 95% confidence interval 1.12-1.32) or anxiety (standardized mean difference = 1.01, 95% confidence interval 0.90-1.12) trials. There was a large amount of heterogeneity in placebo improvement between studies (Q = 899, df = 110, p < 0.001, I-2 = 88%). A greater number of study sites and a later publication year were associated with a greater magnitude of placebo improvement and response rate. Presence of a placebo lead-in and absence of non-US sites were associated with a reduced magnitude of placebo improvement. Trial duration was positively associated with the magnitude of placebo improvement in depression trials but negatively associated with the magnitude of placebo improvement in anxiety and obsessive-compulsive disorder trials. Conclusions Magnitude of placebo symptom improvement differed significantly based on diagnostic indication with improvement being significantly less in obsessive-compulsive disorder than anxiety and depression. Some trial characteristics were associated with a greater magnitude of placebo improvement in trials across disorders but others were disorder specific