Reactor power dependency of the neutron flux parameters fork 0-standardization

Using the facilities of the Triga Mark III reactor at the NNRI, Mexico and the HAV-1 multipurpose monitor, the reactor power dependency for thek ₀-standardization essential neutron flux parameters as: epithermal shape factor (), thermal to epithermal ratio (f) and neutron temperature (T _n ) were experimentally obtained. Evaluation of the obtained dependencies shows that it is unnecessary to analyze the possible introduction of correction factors in thek ₀-INAA experimental results. A single experimental procedure to determine throughf is suggested.     

Recherches théoriques sur la structure électronique de molécules contenant des atomes hybridés en sp

Résumé La structure de la molécule d'allène est étudiée à l'aide de la méthode LCAO améliorée. On met en évidence la nécessité d'introduire d'une part l'interaction des systèmes et avec les liaisons C-H et d'autre part un déplacement d'électrons dans les liaisons C-H. La distance interatomique C₁-C₂ est alors bien retrouvée et les charges nettes, presque nulles, sont en accord avec ce que suggère la réactivité chimique de la molécule. La transition permise A ₁ B ₂ est trouvée en bonne place; les trois autres étant un peu basses. Le problème de la réduction des intégrales faisant intervenir la couche 1s est abordé.

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The improved LCAO theory is used to study the structure of the allene molecule. We show that we must introduce on the one hand the interaction of the and systems with the C-H bonds and on the other hand an electrons displacement in the C-H bonds. The bond distance C₁-C₂ is then found in good agreement with the experimental value and the net charges, almost null, are in agreement with what suggests the chemical reactivity of the molecule. The allowed transition A ₁ B ₂ is found at the right place; the other three being a little low. The problem of the integrals reduction, making to intervene the 1s shell, is approached.

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Zusammenfassung Die Struktur von Allen wird mit Hilfe der verbesserten LCAO-Methode untersucht. Es wird gezeigt, daß eine Wechselwirkung zwischen - und -System mit den C-H-Bindungen und eine Elektronenverschiebung längs der C-H-Bindungen eingeführt werden müssen. Der C₁-C₂-Bindungsabstand stimmt mit der Erfahrung überein. Die Nettoladungen sind fast Null, wie die chemische Reaktivität zeigt. Der erlaubte Übergang A ₁ B ₂ wird gut plaziert angegeben; aber die drei anderen liegen ein wenig zu tief. Das Problem der Integralreduktion mit 1s-Atomorbitalen wird behandelt.

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Nous tenons à remercier ici M. le Professeur André Julg (Laboratoire de Chimie Théorique, Faculté des Sciences, Marseille) pour les nombreuses discussions que nous avons eues avec lui sur ce sujet, et qui a bien voulu relire le manuscrit.

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Les calculs numériques ont été effectués par nos soins sur l'ordinateur PB 250 du Centre de Calcul Numérique de la Faculté des Sciences de Marseille.     

Infrared emission spectroscopy of liquid samples with multivariate calibration as a model for process analytical applications

Infrared emission spectroscopy and multivariate calibration are used to provide a method for the quantitative analysis of liquid samples. Differing forms of the data including second derivative and interferogram representation are used for prediction of sample composition, thickness and temperature. Comparisons are made with transmission measurements of the same samples. In some situations emission measurements may be the preferred method of analysis.     

Herbicide and degradate flux in the Yazoo River Basin

During 1996-1997, water samples were collected from five sites in the Yazoo River Basin and analysed for 14 herbicides and nine degradates. These included acetochlor, alachlor, atrazine, cyanazine, fluometuron, metolachlor, metribuzin, molinate, norflurazon, prometryn, propanil, propazine, simazine, trifluralin, three degradates of fluometuron, two degradates of atrazine, one degradate of cyanazine, norflurazon, prometryn, and propanil. Fluxes generally were higher in 1997 than in 1996 due to a greater rainfall in 1997 than 1996. Fluxes were much larger from streams in the alluvial plain (an area of very productive farmland) than from the Skuna River in the bluff hills (an area of small farms, pasture, and forest). Adding the flux of the atrazine degradates to the atrazine flux increased the total atrazine flux by an average of 14.5%. The fluometuron degradates added about 10% to the total fluometuron flux, and adding the norflurazon degradate flux to the norflurazon flux increased the flux by 82% in 1996 and by 171% in 1997.     

Organ Repair,Hemostasis, and In Vivo Bonding of Medical Devices by Aqueous Solutions of Nanoparticles

Sutures are traumatic to soft connective tissues, such as liver or lungs. Polymer tissue adhesives require complex in vivo control of polymerization or cross‐linking reactions and currently suffer from being toxic, weak, or inefficient within the wet conditions of the body. Herein, we demonstrate using Stöber silica or iron oxide nanoparticles that nanobridging, that is, adhesion by aqueous nanoparticle solutions, can be used in vivo in rats to achieve rapid and strong closure and healing of deep wounds in skin and liver. Nanoparticles were also used to fix polymer membranes to tissues even in the presence of blood flow, such as occurring after liver resection, yielding permanent hemostasis within a minute. Furthermore, medical devices and tissue engineering constructs were fixed to organs such as a beating heart. The simplicity, rapidity, and robustness of nanobridging bode well for clinical applications, surgery, and regenerative medicine.