A rigorous lower bound for the stability regions of the quadratic map

We establish a lower bound on the measure of the set of stable parameters a for the quadratic map Q_a(x)=ax(1−x). For these parameters, we prove that Q_a either has a single stable periodic orbit or a period-doubling bifurcation. From this result, we also obtain a non-trivial upper bound on the set of stochastic parameters for Q_a.     

Structure of 4-amino-3-butyl-1,2,4-triazole-5-thione: Relation to derivatives with H, Me, Et, and Pr in the 3-position

The compound 4-amino-3-butyl-1,2,4-triazole-5-thione [crystal data: C₆H₁₂N₄S, triclinic, P , Z = 2, a = 7.546(2), b = 11.217(3), c = 5.681(1) ?, α = 103.12(2), β = 91.33(2), γ = 72.41(2)°, V = 445.9(2) ?³] contains an essentially planar triazole ring with the butyl group rotated out of the plane by approximately 104°. The molecules form hydrogen-bonded dimers through intermolecular N–HS interactions involving the thione sulfur atom and the protonated nitrogen atom on the ring. These units are then linked into columns through N–HN hydrogen bonds between the amine group and the unsubstituted ring N atom of adjacent molecules. The structural features of this compound are compared with those of the corresponding triazoles with H, methyl, ethyl and propyl groups on the 3-carbon.     

The micro-determination of carbon and hydrogen in fluorine-containing organic compounds

Summary The sample is burned in a silica combustion tube, using a 4 ml per minute oxygen stream. Oxidation of the combustion products is completed by passing them over a platinum contact heated to 750°C, after the manner ofFriedrich. Silver wool at the same temperature removes sulphur and halogens, including the fluorine from any hydrogen fluoride produced, and granular sodium fluoride at about 270°C is used to absorb silicon tetrafluoride.The water vapour and carbon dioxide are determined in the usual way by absorption in magnesium perchlorate and soda-asbestos respectively. Satisfactory results have been obtained for the analyses of 4 mg samples of compounds containing the elements C, H, O, F, the standard deviation of the results for hydrogen being about ±0,1% H and for carbon being about ±0,2% C.Preliminary work indicates that fluorocarbons may be analysed if water-vapour is introduced into the system, and that the presence of nitrogen in compounds presents no difficulty when an external absorbent for nitrogen oxides is used. Certain refinements are included, which are applicable to the conventional apparatus for micro carbon and hydrogen determination.

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Zusammenfassung Zur Bestimmung von Kohlenstoff und Wasserstoff in fluorhaltigen organischen Verbindungen wird die Substanz in einem Quarzverbrennungsrohr im Sauerstoffstrom von 4 ml/Minute verbrannt. Die vollständige Oxydation der Verbrennungsprodukte erfolgt nachFriedrich durch Überleiten über einen Platinkontakt bei 750°C. Bei derselben Temperatur hält Silberwolle Schwefel und alle Halogene einschließlich Fluor zurück, soweit es als Fluorwasserstoff vorliegt. Zur Absorption von Siliciumtetrafluorid wird gekörntes Natriumfluorid bei etwa 270°C verwendet.Wasserdampf und Kohlendioxyd werden in der üblichen Weise mittels Magnesiumperchlorat bzw. Natronasbest bestimmt. Bei Einwaagen von 4 mg Substanz irgendeiner Verbindung der Elemente C, H, O und F werden befriedigende Ergebnisse erhalten. Die durchschnittlichen Abweichungen von der Theorie betragen für Wasserstoff etwa ±0,1%, bei Kohlenstoff etwa ±0,2%.Vorversuche haben gezeigt, daß fluorhältige Kohlenwasserstoffe bei gleichzeitiger Zufuhr von Wasserdampf in die Apparatur analysiert werden können und daß die Gegenwart von Stickstoff in der Analysensubstanz keine Schwierigkeiten mit sich bringt, wenn ein zusätzliches Absorptionsmittel für Stickstoffoxyde vorgesehen ist. Einige Verbesserungen der herkömmlichen Apparatur für die Mikro-C-H-Bestimmung werden angeführt.

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Résumé L'échantillon est brûlé dans un tube à combustion en silice, utilisant un débit d'oxygène de 4 ml par minute. L'oxydation des produits de combustion se complète en les faisant passer sur un contact de platine chauffé à 750° C d'après le procédé deFriedrich. La laine d'argent à la même température élimine le soufre et les halogènes y compris le fluor de tout fluorure produit et le fluorure de sodium granulaire à 270° environ sert à absorber le tétrafluorure de silicium.La vapeur d'eau et le gaz carbonique sont dosés comme d'habitude par absorption sur le perchlorate de magnésium et l'amiante sodé respectivement. Des résultats satisfaisants ont été obtenus pour les analyses de 4 mg d'échantillons de composés contenant les éléments C, H, O, F; l'erreur moyenne des résultats pour l'hydrogène étant ±0,1% H et pour le carbone, environ ± 0,2% C.Un travail préliminaire indique que les hydrocarbures fluorés peuvent être analysés si l'on introduit de la vapeur d'eau dans le système et que la présence d'azote dans les composés ne présente pas de difficulté quand on utilise un absorbant extérieur pour les oxydes de l'azote. Certaines améliorations applicables à l'appareil classique pour les microdosages de carbone et d'hydrogène sont incluses.

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With 4 Figures.     

Mercurous nitrate as a reductimetric reagent : The titration of various oxidising agents

It has been found that when excess of a solution containing ferrous ions is added to certain oxidising agents, the equivalent amount of ferric iron produced can be titrated accurately with mercurous nitrate, enabling the original oxidant to be assessed. Oxidising agents which have been determined in this way are potassium permanganate, potassium persulphate, ceric sulphate, sodium vanadate, potassium chlorate, hydrogen peroxide and potassium dichromate. The last substance provides a convenient primary standard for the standardisation of mercurous nitrate solutions.     

On the automorphisms of Paley's type II Hadamard matrix

In this paper we determine the automorphism group of Paley's type II Hadamard matrix.     

Circulating hemocytes from larvae of Melipona scutellaris (Hymenoptera,Apidae, Meliponini): Cell types and their role in phagocytosis

Infection in insects stimulates a complex defensive response. Recognition of pathogens may be accomplished by plasma or hemocyte proteins that bind specifically to bacterial or fungal polysaccharides. Several morphologically distinct hemocyte cell types cooperate in the immune response. Hemocytes attach to invading organisms and then isolate them by phagocytosis, by trapping them in hemocyte aggregates called nodules, or by forming an organized multicellular capsule around large parasites. In the current investigation the cellular in the hemolymph third instar larvae of M. scutellaris has been characterized by means of light microscopy analysis and phagocytosis assays were performed in vivo by injection of 0.5 μm fluorescence beads in order to identify the hemocyte types involved in phagocytosis. Four morphotypes of circulating hemocytes were found in 3rd instar larvae: prohemocytes, plasmatocytes, granulocytes and oenocytoids. The results presented plasmatocytes and granulocytes involved in phagocytic response of foreign particles in 3rd instar larvae of M. scutellaris.     

SENSITIVITY OF MONONUCLEAR CELLS TO UV RADIATION

Abstract—The viability of peripheral blood mononuclear cells, as measured by trypan blue dye exclusion, is decreased by exposure to UV radiation in vitro . The toxicity of the UV radiation is doseand wavelength-dependent; UVC is approximately 10 times more effective than UVB and 10⁵ times more effective than UVA.     

Submicro determination of cobalt, manganese or nickel in organometallic compounds

Methods for the determination of cobalt, manganese or nickel in samples of organometallic compounds weighing 30-100 mug have been developed. Spectrophotometric determination following digestion with nitric and sulphuric acids in a sealed tube is recommended, all results obtained from the analysis of standard compounds being within +/-0.4% absolute error. Digestion in an open tube with perchloric and sulphuric acids gives slightly low results for cobalt and nickel compounds and is inappropriate for manganese compounds.     

The micro-determination of carbon and hydrogen in organic compounds containing phosphorus

Several reagents have been examined for use in the micro-determination of carbon and hydrogen in organic compounds containing phosphorus for which low carbon values had previously been reported. Tungstic oxide was found to be the most convenient reagent for this purpose. A modification of the procedure of Friedrich was used throughout this investigation which is suitable for universal application.     

Bio-deuterated cellulose thin films for enhanced contrast in neutron reflectometry

Novel molecularly smooth, flat and thin films of regenerated bio-deuterated cellulose were produced for enhanced contrast with adsorbed molecules in neutron reflectivity (NR) and for cellulose structure studies. The cellulose films were produced to study both the solid/air interface and the solid/liquid interface. Cellulose films with a wide range of scattering contrast were achieved by combining exchange of ¹H for deuterium on hydroxyl groups via water in the liquid phase and via biosynthesis of deuterated bacterial cellulose by Gluconacetobacter xylinus which can deuterate the hydrogens bonded to carbon atoms in cellulose. The deuterated cellulose combined with NR will help to provide new information on the interaction of various (bio)-macromolecules and cellulose. This includes quantifying and visualizing the density profile of polymers and biomolecules adsorbed onto cellulose surface. The potential of this material for IR studies of materials adsorbed to cellulose films is briefly discussed.