Epoxide polymerization

Summary Poly(propylene oxide), PPO, obtained using diphenylzinc, Ph₂Zn, and using the diphenylzinc-water system at various molar ratios H₂O/Ph₂Zn, were studied through ¹H NMR and IR spectroscopy establishing that the polymerization initiates by coordition of propylene oxide (PO) to a terminal zinc atom of the active species followed by consecutive insertions of PO units at this zinc atom. The PPO obtained showed Ph-and HO-, HO-and HO-end-groups depending on the molar ratio H₂O/Ph²Zn used, and also HO-and PhO-end-groups when oxygen was present in the polymerization system.     

Fatty acid composition of total lipids,neutral lipids and phospholipids in wild and farmed matrinxã (Brycon cephalus) in the Brazilian Amazon area

BACKGROUND: The chemical composition of Amazonian fish is extremely variable, being influenced by the season and the type and amount of food. A special interest in the fish oil composition has been developed owing to the presence of essential fatty acids, since this is directly related to human health. This study aimed to investigate the fatty acid composition (FAC) of the total lipid (TL), neutral lipid (NL) and phospholipid (PL) fractions of the dorsal muscle and orbital cavity of farmed and wild matrinxã in the Amazon area captured in different seasons. RESULTS: Fatty acids (FA) were analysed by high‐resolution gas chromatography/mass spectrometry. Sixty‐five FA were detected in the TL, 66 in the NL and 55 in the PL. The main FA found in farmed and wild fish were oleic, palmitic, stearic and linoleic acids. No distinctions in the quality or quantity of these fractions between dorsal muscle and orbital cavity were found. CONCLUSION: The season had a significant influence on the TL and FAC. Fish captured during the dry season showed lower levels of lipid and a higher percentage of long‐chain polyunsaturated fatty acids. Matrinxã farmed in a semi‐intensive system showed a nutritional quality comparable to that of wild matrinxã captured in the wet season. Copyright © 2007 Society of Chemical Industry     

Structural Analogies and Differences Between Graphite Oxide and C60 and C70 Polymeric Oxides (Fullerene Ozopolymers)

A brief survey of the chemical structural analogies and differences between graphite oxide and fullerene ozopolymers or polymeric fullerene oxides (PFO) is presented. Graphite oxide is the product of oxidation of graphite prepared with strong oxidizing agents while PFO is the products formed by prolonged ozonation of C₆₀ or C₇₀ in solution. Notwithstanding the different starting substrates and oxidation conditions, elemental analyses, FT-IR spectroscopy and ¹³C-NMR spectroscopy suggest a very similar chemical structure for graphite oxide and PFO. A further analogy is the possibility to perform reduction or oxidation reactions on both substrates considered. Graphite oxide and PFO have also in common the ability to act as ion exchangers and as metal ion binders. Even the thermal behavior is comparable. However, X-ray powder diffraction has confirmed that graphite oxide still has a layered structure derived from graphite but with the graphene sheets at much bigger distance from each other due to the intercalation of oxidized groups and solvent molecules, while PFO do not show at all any sign of layered structure either from the X-ray spectra and also by its behavior in solution which is strikingly different from that shown by graphite oxide.     

Transplantectomy today: indications and complications

Analysis of the indications for transplantectomy and its complications over a 12-year period. Over a total of 159 failure grafts, we performed 53 transplantectomies (33.3%). The percentage of complications was 16.9%. Three patients died (5.6%) during the more or less immediate post-operative period. In our experience, consistent and prolonged maintenance of immunosuppression should avoid the need for transplantectomy in a high percentage of grafts. Only 15 transplantectomies were made on 104 failure grafts after 6 months (14.4%). Our short but successful experience with embolization of 2 rejected grafts confirms the validity of this conservative alternative versus conventional surgical transplantectomy in selected cases.     

An optimal algorithm for the boundary of a cell in a union of rays

In this paper we study a cell of the subdivision induced by a union ofn half-lines (or rays) in the plane. We present two results. The first one is a novel proof of theO(n) bound on the number of edges of the boundary of such a cell, which is essentially of methodological interest. The second is an algorithm for constructing the boundary of any cell, which runs in optimal (n logn) time. A by-product of our results are the notions of skeleton and of skeletal order, which may be of interest in their own right.This work was partly supported by CEE ESPRIT Project P-940, by the Ecole Normale Supérieure, Paris, and by NSF Grant ECS-84-10902.This work was done in part while this author was visiting the Ecole Normale Supérieure, Paris, France.     

Transporting Deformations of Face Emotions in the Shape Spaces: A Comparison of Different Approaches

Studying the changes of shape is a common concern in many scientific fields. We address here two problems: (1) quantifying the deformation between two given shapes and (2) transporting this deformation to morph a third shape. These operations can be done with or without point correspondence, depending on the availability of a surface matching algorithm, and on the type of mathematical procedure adopted. In computer vision, the re-targeting of emotions mapped on faces is a common application. We contrast here four different methods used for transporting the deformation toward a target once it was estimated upon the matching of two shapes. These methods come from very different fields such as computational anatomy, computer vision and biology. We used the large diffeomorphic deformation metric mapping and thin plate spline, in order to estimate deformations in a deformational trajectory of a human face experiencing different emotions. Then we use naive transport (NT), linear shift (LS), direct transport (DT) and fanning scheme (FS) to transport the estimated deformations toward four alien faces constituted by 240 homologous points and identifying a triangulation structure of 416 triangles. We used both local and global criteria for evaluating the performance of the 4 methods, e.g., the maintenance of the original deformation. We found DT, LS and FS very effective in recovering the original deformation while NT fails under several aspects in transporting the shape change. As the best method may differ depending on the application, we recommend carefully testing different methods in order to choose the best one for any specific application.

     

Changes in free amino acids content in albacore (Thunnus alalunga) muscle during thermal processing

Summary The effects of cooking and sterilization at several temperatures on the free amino acids (FAA) content in albacore (Thunnus alalunga) muscle were studied during the processing of canned tuna. FAAs were derivatized witho-phtalaldehyde, separated on a C18 column by HPLC and detected by both fluorescence and ultra-violet detectors. After cooking the loss of FAAs was not significant. However, in the final product sterilized at 115 °C and 110 °C (throughout the whole process) there were significant losses with regard to the start material, but not at 118 °C (all temperatures leading to the same lethal F-value). The influence of the thermal process time at 115 °C was evaluated for 60 and 100 min. Significant losses were found between both canned products (25%) and between the raw fish and the final product (12% and 34%, process time 60 and 100 min, respectively). The determination of the content of FAA present in canned albacore may be a useful indication of the severity of the thermal processing.

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Veränderung im Gehalt an freien Aminosäuren in Thunfischmuskel (Tunnus alalunga) während der Wärmebehandlung

Zusammenfassung Die Wirkung des Kochens und Sterilisierens bei verschiedenen Temperaturen auf den Gehalt an freien Aminosäuren (FAA) im Thunfischmuskel (Thunnus alalunga) wurde während der Herstellung von Thunfischkonserven untersucht. Die freien Aminosäuren wurden mito-Phtalaldehyd derivatisiert, auf einer C-18-Kolonne mit HPLC abgetrennt und durch Fluorescenz und UV-Detektoren nachgewiesen. Nach dem Kochen war der Verlust an FAA nicht signifikant, jedoch in dem bei 110° und 115 °C sterilisierten Endprodukt ergaben sich signifikante Verluste bezogen auf das Ausgangsmaterial, aber nicht auf das bei 118 °C erhitzte; alle Erhitzungstemperaturen führen zu demselben letalen F-Wert. Der Zeiteinfluß der Erhitzung bei 115 °C wurde bei 60 und 100 min bewertet. Signifikante Verluste sind bei beiden Dosenkonserven aufgetreten (25%) und zwischen diesen und dem Rohfisch ( 12% und 34%) bei einer Erhitzungszeit von 60 und 100 min). Die Bestimmung des FAA-Gehalts in Thunfischkonserven kann für den Nachweis der Einwandfreiheit des thermischen Prozesses sehr nützlich sein.

     

Methamphetamine Blocks Adenosine A2A Receptor Activation via Sigma 1 and Cannabinoid CB1 Receptors

Methamphetamine is, worldwide, one of the most consumed drugs of abuse. One important side effect is neurodegeneration leading to a decrease in life expectancy. The aim of this paper was to check whether the drug affects one of the receptors involved in neurodegeneration/neuroprotection events, namely the adenosine A_2A receptor (A_2AR). First, we noticed that methamphetamine does not affect A_2A functionality if the receptor is expressed in a heterologous system. However, A_2AR becomes sensitive to the drug upon complexes formation with the cannabinoid CB₁ receptor (CB₁R) and the sigma 1 receptor (σ₁R). Signaling via both adenosine A_2AR and cannabinoid CB₁R was affected by methamphetamine in cells co-expressing the two receptors. In striatal primary cultures, the A_2AR–CB₁R heteromer complex was detected and methamphetamine not only altered its expression but completely blocked the A_2AR- and the CB₁R-mediated activation of the mitogen activated protein kinase (MAPK) pathway. In conclusion, methamphetamine, with the participation of σ₁R, alters the expression and function of two interacting receptors, A_2AR, which is a therapeutic target for neuroprotection, and CB₁R, which is the most abundant G protein-coupled receptor (GPCR) in the brain.